[REL] bump to v0.24.1

closes #414

README.md

@@ -4,7 +4,7 @@ _A no nonsense web framework for structured, dynamic and maintainable applicatio
 
 ## Project Overview
 
-The Odoo Web Library (OWL) is a smallish (~17kb gzipped) UI framework intended to
+The Odoo Web Library (OWL) is a smallish (~18kb gzipped) UI framework intended to
 be the basis for the [Odoo](https://www.odoo.com/) Web Client. Owl is a modern
 framework, written in Typescript, taking the best ideas from React and Vue in a
 simple and consistent way. Owl's main features are:
@@ -20,25 +20,24 @@ virtual dom, integrates beautifully with hooks, and the rendering is asynchronou
 **Try it online!** An online playground is available at [https://odoo.github.io/owl/playground](https://odoo.github.io/owl/playground) to let you experiment with the Owl framework. There
 are some code examples to showcase some interesting features.
 
+Owl is currently mostly stable.  Possible future changes are explained in the
+[roadmap](roadmap.md).
+
 ## Example
 
 Here is a short example to illustrate interactive components:
 
 ```javascript
-import { Component, QWeb, useState } from "owl";
-import { xml } from "owl/tags";
+const { Component, QWeb, useState } = owl;
+const { xml } = owl.tags;
 
 class Counter extends Component {
   static template = xml`
-    <button t-on-click="increment">
+    <button t-on-click="state.value++">
       Click Me! [<t t-esc="state.value"/>]
     </button>`;
 
   state = useState({ value: 0 });
-
-  increment() {
-    this.state.value++;
-  }
 }
 
 class App extends Component {
@@ -55,8 +54,8 @@ const app = new App({ qweb: new QWeb() });
 app.mount(document.body);
 ```
 
-Note that the counter component is made reactive with the [`useState`](doc/hooks.md#usestate)
-hook. Also, all examples here uses the `xml` helper to define inline templates.
+Note that the counter component is made reactive with the [`useState` hook](doc/reference/hooks.md#usestate).
+Also, all examples here uses the [`xml` helper](doc/reference/tags.md#xml-tag) to define inline templates.
 But this is not mandatory, many applications will load templates separately.
 
 More interesting examples can be found on the
@@ -94,8 +93,8 @@ A complete documentation for Owl can be found here:
 The most important sections are:
 
 - [Quick Start](doc/quick_start.md)
-- [Component](doc/component.md)
-- [Hooks](doc/hooks.md)
+- [Component](doc/reference/component.md)
+- [Hooks](doc/reference/hooks.md)
 
 Found an issue in the documentation? A broken link? Some outdated information?
 Submit a PR!
@@ -104,8 +103,8 @@ Submit a PR!
 
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-0.23.0.js](https://github.com/odoo/owl/releases/download/v0.23.0/owl.js)
-- [owl-0.23.0.min.js](https://github.com/odoo/owl/releases/download/v0.23.0/owl.min.js)
+- [owl-0.24.1.js](https://github.com/odoo/owl/releases/download/v0.24.1/owl.js)
+- [owl-0.24.1.min.js](https://github.com/odoo/owl/releases/download/v0.24.1/owl.min.js)
 
 Some npm scripts are available:
 
@@ -129,7 +128,7 @@ Owl components in an application are used to define a (dynamic) tree of componen
 ```
 
 **Environment:** the root component is special: it is created with an environment,
-which should contain a `QWeb` instance. The environment is then automatically
+which should contain a [`QWeb` instance](doc/reference/qweb.md). The environment is then automatically
 propagated to each sub components (and accessible in the `this.env` property).
 
 ```js
@@ -187,6 +186,12 @@ class Counter extends Component {
 }
 ```
 
+Note that the `t-on-click` handler can even be replaced by an inline statement:
+
+```xml
+    <button t-on-click="state.value++">
+```
+
 **Props:** sub components often needs some information from their parents. This
 is done by adding the required information to the template. This will then be
 accessible by the sub component in the `props` object. Note that there is an
@@ -250,7 +255,7 @@ class Parent extends Component {
 In this example, the `OrderLine` component trigger a `add-to-order` event. This
 will generate a DOM event which will bubble along the DOM tree. It will then be
 intercepted by the parent component, which will then get the line (from the
-`detail` key) and then increment its quantity. See the section on [event handling](doc/component.md#event-handling)
+`detail` key) and then increment its quantity. See the section on [event handling](doc/reference/component.md#event-handling)
 for more details on how events work.
 
 Note that this example would have also worked if the `OrderLine` component

doc/architecture/rendering.md

@@ -0,0 +1,34 @@
+# 🦉 Rendering Pipeline 🦉
+
+We explain here how Owl is designed, from the perspective of its rendering
+pipeline.
+
+Warning: these notes are technical by nature, and intended for people working
+on Owl (or interested in understanding its design).
+
+## Overview
+
+A rendering occurs in two phases:
+
+- virtual rendering: this generates the virtual dom in memory, asynchronously
+- patch: applies a virtual tree to the screen (synchronously)
+
+
+There are several classes involved in a rendering:
+
+- components
+- a scheduler
+- fibers: small objects containing some metadata, associated with a rendering of
+  a specific component
+
+
+Components are organized in a dynamic component tree, visible in the user
+interface.  Whenever a rendering is initiated in a component `C`:
+- a fiber is created on `C` with the rendering props information
+- the virtual rendering phase starts on C (will asynchronously render all the
+  child components)
+- the fiber is added to the scheduler, which will poll continuously, every
+  animation frame, if the fiber is done
+- once it is done, the scheduler will call the task callback, which will apply
+  the patch (if it was not cancelled in the meantime).
+

doc/comparison.md

@@ -3,7 +3,7 @@
 OWL, React and Vue have the same main feature: they allow developers to build
 declarative user interfaces. To do that, all these frameworks uses a virtual dom. However, there are still obviously many differences.
 
-In this page, we try to highlight some of these differences. Obviously, some
+In this page, we try to highlight some of these differences. Obviously, a lot of
 effort was done to be fair. However, if you disagree with some of the points
 discussed, feel free to open an issue/submit a PR to correct this text.
 
@@ -16,6 +16,7 @@ discussed, feel free to open an issue/submit a PR to correct this text.
 - [Asynchronous rendering](#asynchronous-rendering)
 - [Reactiveness](#reactiveness)
 - [State Management](#state-management)
+- [Hooks](#hooks)
 
 ## Size
 
@@ -24,11 +25,16 @@ than React and Vue. Also, jQuery is not the same kind of framework, but it is in
 
 | Framework                | Size (minified, gzipped) |
 | ------------------------ | ------------------------ |
-| OWL                      | 16kb                     |
+| OWL                      | 18kb                     |
 | Vue + VueX               | 30kb                     |
+| Vue + VueX + Vue Router  | 39kb                     |
 | React + ReactDOM + Redux | 40kb                     |
 | jQuery                   | 30kb                     |
 
+Note that those comparisons are not entirely fair, because we do not compare
+the same exact set of features. For example, VueX and Vue Router support more
+advanced use cases.
+
 ## Class Based
 
 Both React and Vue moved away from defining components with classes. They prefer
@@ -40,6 +46,17 @@ contrast, Owl has only one mechanism: class-based components. We believe that Ow
 components are fast enough for all our usecases, and making it as simple as
 possible for developers is more valuable (for us).
 
+Also, functions or class based components are more than just syntax. Functions
+comes with a mindset of composition and class are about inheritance. Clearly,
+both of these are important mechanisms for reusing code. Also, one does not
+exclude the other.
+
+It certainly looks like the world of UI frameworks is moving toward composition,
+for many very good reasons. Owl is still good at composition (for example,
+Owl supports slots, which is the primary mechanism to make generic reusable
+components). But it can also use inheritance (and this is very important since
+templates can also be inherited with `xpaths` transformations).
+
 ## Tooling/Build step
 
 OWL is designed to be easy to use in a standalone way. For various reasons,
@@ -50,13 +67,23 @@ be used by simply adding a script tag to a page.
 <script src="owl.min.js" />
 ```
 
-In comparison, React encourages using JSX,
-which necessitate a build step, and most Vue applications uses single file
-components, which also necessitate a build step.
+In comparison, React encourages using JSX, which necessitate a build step, and
+most Vue applications uses single file components, which also necessitate a build step.
 
 On the flipside, external tooling may make it harder to use in some case, but it
 also brings a lot of benefits. And React/Vue have both a large ecosystem.
 
+Note that since Owl is not dependant on any external tool nor libraries, it is
+very easy to integrate into any build toolchain. Also, since we cannot rely on
+additional tools, we made a lot of effort to make the most of the web platform.
+
+For example, Owl uses the standard `xml` parser that comes with every browser.
+Because of that, Owl did not have to write its own template parser. Another
+example is the [`xml`](reference/tags.md#xml-tag) tag helper function, which makes use of
+native template literals to allow in a natural way to write `xml` templates
+directly in the javascript code. This can be easily integrated with editor
+plugins to have autocompletion inside the template.
+
 ## Templating
 
 OWL uses its own QWeb engine, which compiles templates on the
@@ -79,7 +106,8 @@ into javascript functions. Note that Vue has a separate build which includes the
 template compiler.
 
 In contrast, most React applications do not use a templating language, but write
-some JSX code, which is precompiled into plain JavaScript by a build step.
+some JSX code, which is precompiled into plain JavaScript by a build step. This
+example is done with the (kind of outdated) React class system:
 
 ```jsx
 class Clock extends React.Component {
@@ -98,6 +126,20 @@ This has the advantage of having the full power of Javascript, but is less
 structured than a template language. Note that the tooling is quite impressive:
 there is a syntax highlighter for jsx here on github!
 
+By comparison, here is the equivalent Owl component, written with the
+[`xml`](reference/tags.md#xml-tag) tag helper:
+
+```js
+class Clock extends Component {
+  static template = xml`
+      <div>
+        <h1>Hello, world!</h1>
+        <h2>It is {props.date.toLocaleTimeString()}.</h2>
+      </div>
+    `;
+}
+```
+
 ## Asynchronous Rendering
 
 This is actually a big difference between OWL and React/Vue: components in OWL
@@ -127,12 +169,14 @@ This may be dangerous (to stop the rendering waiting for the network), but it is
 extremely powerful as well, as demonstrated by the Odoo Web Client.
 
 Lazy loading static libraries can obviously be done with React/Vue, but it is
-more convoluted.
+more convoluted. For example, in Vue, you need to use a dynamic import keyword
+that needs to be transpiled at build time in order for the component to be loaded
+asynchronously (see [the documentation](https://vuejs.org/v2/guide/components-dynamic-async.html#Async-Components)).
 
 ## Reactiveness
 
 React has a simple model: whenever the state changes, it is
-replaced with a new state (via the setState method). Then, the DOM is patched.
+replaced with a new state (via the `setState` method). Then, the DOM is patched.
 This is simple, efficient, and a little bit awkward to write.
 
 Vue is a little bit different: it replace magically the properties in the state
@@ -207,30 +251,94 @@ keeps track of who get data, and retrigger a render when it was changed.
 Owl store is a little bit like a mix of redux and vuex: it has actions (but not
 mutations), and like VueX, it keeps track of the state changes. However, it does
 not notify a component when the state changes. Instead, components need to connect
-to the store like in redux, by inheriting the `ConnectedComponent` class.
+to the store like in redux, with the `useStore` hook (see the [store documentation](reference/store.md#connecting-a-component)).
 
 ```javascript
 const actions = {
   increment({ state }, val) {
-    state.counter += val;
+    state.counter.value += val;
   }
 };
 
 const state = {
-  counter: 0
+  counter: { value: 0 }
 };
 const store = new owl.Store({ state, actions });
 
-class Counter extends owl.ConnectedComponent {
-  static mapStoreToProps(state) {
-    return {
-      value: state.counter
-    };
-  }
-  increment() {
-    this.env.store.dispatch("increment");
-  }
+class Counter extends Component {
+  static template = xml`
+      <button t-name="Counter" t-on-click="dispatch('increment')">
+        Click Me! [<t t-esc="counter.value"/>]
+      </button>`;
+  counter = useStore(state => state.counter);
+  dispatch = useDispatch();
 }
 
 const counter = new Counter({ store, qweb });
 ```
+
+## Hooks
+
+[Hooks](https://reactjs.org/docs/hooks-intro.html#motivation) recently took over
+the React world. They solve a lot of seemingly unconnected problems: attach
+reusable behavior to a component, in a composable way, extract stateful logic
+from a component or reuse stateful logic between component, without changing your
+component hierarchy.
+
+Here is an example of the React `useState` hook:
+
+```js
+import React, { useState } from "react";
+
+function Example() {
+  // Declare a new state variable, which we'll call "count"
+  const [count, setCount] = useState(0);
+
+  return (
+    <div>
+      <p>You clicked {count} times</p>
+      <button onClick={() => setCount(count + 1)}>Click me</button>
+    </div>
+  );
+}
+```
+
+Because of the way React designed the hooks API, they only work for functional
+components. But in that case, they really are powerful. Every major React library
+is in the process of redesigning their API with hooks (for example,
+[Redux](https://react-redux.js.org/next/api/hooks)).
+
+Vue 2 does not have hooks, but the Vue project is working on its next version,
+which will feature its new [composition API](https://vue-composition-api-rfc.netlify.com/).
+This work is based on the new ideas introduced by React hooks.
+
+From the way React and Vue introduce their hooks, it may look like hooks are not
+compatible with class components. However, this is not the case, as shown by
+Owl [hooks](reference/hooks.md). They are inspired by both React and Vue. For example,
+the `useState` hook is named after React, but its API is closer to the `reactive`
+Vue hook.
+
+Here is what the `Counter` example above look like in Owl:
+
+```js
+import { Component, Owl } from "owl";
+import { xml } from "owl/tags";
+
+class Example extends Component {
+  static template = xml`
+      <div>
+        <p>You clicked {count.value} times</p>
+        <button t-on-click="increment">Click me</button>
+      </div>`;
+
+  count = useState({ value: 0 });
+
+  increment() {
+    this.state.value++;
+  }
+}
+```
+
+Since the Owl framework had hooks from early in its life, its main APIs
+are designed to be interacted with hooks from the start. For example, the
+`Context` and `Store` abstractions.

doc/observer.md

@@ -1,20 +0,0 @@
-# 🦉 Observer 🦉
-
-Owl need to be able to react to state changes. For example, whenever the state
-of a component is changed, we need to rerender it. To help with that, we have
-an Observer class. Its job is to observe some object state, and react to any
-change. To do that, it recursively replace all keys of the observed state by
-getters and setters.
-
-For example, this code will display `update` in the console:
-
-```javascript
-const observer = new owl.Observer();
-observer.notifyCB = () => console.log("update");
-const obj = observer.observe({ a: { b: 1 } });
-
-obj.a.b = 2;
-```
-
-The observer is implemented with the native `Proxy` object. Note that this
-means that it will not work on older browsers.

doc/quick_start.md

@@ -55,7 +55,7 @@ To build an application (or a sub-part of an application), we need two things:
 
 - an environment: it is the global context in which we are working. It needs to
   contain a QWeb instance (preloaded with templates), and anything else that we
-  need. In practice, it could context some user session information, some
+  need. In practice, it could be used to contain some user session information, some
   configuration keys (for example, isMobile = true/false if we are in mobile mode).
 
 - a description of the user interface: there should be a root component, which can
@@ -76,10 +76,7 @@ const useState = owl.hooks.useState;
 
 class ClickCounter extends owl.Component {
   static template = "clickcounter";
-  constructor() {
-    super(...arguments);
-    this.state = useState({ value: 0 });
-  }
+  state = useState({ value: 0 });
 
   increment() {
     this.state.value++;
@@ -90,9 +87,9 @@ class ClickCounter extends owl.Component {
 // Application initialization
 //------------------------------------------------------------------------------
 async function start() {
-  const templates = await owl.utils.loadTemplates("templates.xml");
+  const templates = await owl.utils.loadFile("templates.xml");
   const env = {
-    qweb: new owl.QWeb(templates)
+    qweb: new owl.QWeb({ templates })
   };
   const counter = new ClickCounter(env);
   const target = document.getElementById("main");

doc/readme.md

@@ -29,6 +29,8 @@ owl
         useStore
         useDispatch
         useGetters
+    misc
+        AsyncRoot
     router
         Link
         RouteComponent
@@ -39,27 +41,27 @@ owl
         debounce
         escape
         loadJS
-        loadTemplates
+        loadFile
+        shallowEqual
         whenReady
 ```
 
-
 Note that for convenience, the `useState` hook is also exported at the root of the `owl` object.
 
 ## Reference
 
-- [Animations](animations.md)
-- [Component](component.md)
-- [Context](context.md)
-- [Event Bus](event_bus.md)
-- [Hooks](hooks.md)
-- [Observer](observer.md)
-- [QWeb](qweb.md)
-- [Router](router.md)
-- [Store](store.md)
-- [Tags](tags.md)
-- [Utils](utils.md)
-- [Virtual DOM](vdom.md)
+- [Animations](reference/animations.md)
+- [Component](reference/component.md)
+- [Context](reference/context.md)
+- [Event Bus](reference/event_bus.md)
+- [Hooks](reference/hooks.md)
+- [Misc](reference/misc.md)
+- [Observer](reference/observer.md)
+- [QWeb](reference/qweb.md)
+- [Router](reference/router.md)
+- [Store](reference/store.md)
+- [Tags](reference/tags.md)
+- [Utils](reference/utils.md)
 
 ## Learning Resources
 
@@ -70,3 +72,11 @@ Note that for convenience, the `useState` hook is also exported at the root of t
 - [Comparison with React/Vue](comparison.md)
 - [Tooling](tooling.md)
 - [Templates to start Owl applications (external link)](https://github.com/ged-odoo/owl-templates)
+
+## Architecture
+
+This section explains in more detail the inner workings of Owl. It is more
+useful for people working on Owl code.
+
+- [Virtual DOM](architecture/vdom.md)
+- [Rendering](architecture/rendering.md)

doc/reference/animations.md

@@ -30,7 +30,7 @@ btn {
 }
 ```
 
-will produce a nice flash effect whenever the user click (or activate with the
+will produce a nice flash effect whenever the user clicks (or activates with the
 keyboard) the button.
 
 ## CSS Transitions
@@ -47,7 +47,7 @@ the lifetime of a node. Since this is not easy to do by hand, Owl `t-transition`
 directive is there to help.
 
 Whenever a node has a `t-transition` directive, with a `name` value, the following
-will happen:
+sequence of events will happen:
 
 At node insertion:
 
@@ -91,6 +91,5 @@ The `t-transition` directive can be applied on a node element or on a component.
 
 Notes:
 
-- more information on animations are available [here](animations.md).
-- Owl does not support more than one transition on a single node, so the
-  `t-transition` expression must be a single value (i.e. no space allowed)
+Owl does not support more than one transition on a single node, so the
+`t-transition` expression must be a single value (i.e. no space allowed).

doc/reference/component.md

@@ -29,7 +29,7 @@
 
 OWL components are the building blocks for user interface. They are designed to be:
 
-1. **declarative:** the user interface should be described in term of the state
+1. **declarative:** the user interface should be described in terms of the state
    of the application, not as a sequence of imperative steps.
 
 2. **composable:** each component can seamlessly be created in a parent component by
@@ -72,7 +72,7 @@ class ClickCounter extends owl.Component {
 Note that this code is written in ESNext style, so it will only run on the
 latest browsers without a transpilation step.
 
-This example show how a component should be defined: it simply subclasses the
+This example shows how a component should be defined: it simply subclasses the
 Component class. If no static `template` key is defined, then
 Owl will use the component's name as template name. Here,
 a state object is defined, by using the `useState` hook. It is not mandatory to use the state object, but it is certainly encouraged. The result of the `useState` call is
@@ -80,33 +80,87 @@ a state object is defined, by using the `useState` hook. It is not mandatory to
 
 ## Reference
 
-An Owl component is a small class which represent a component or some UI element.
+An Owl component is a small class which represents a component or some UI element.
 It exists in the context of an environment (`env`), which is propagated from a
 parent to its children. The environment needs to have a QWeb instance, which
 will be used to render the component template.
 
 Be aware that the name of the component may be significant: if a component does
 not define a `template` key, then Owl will lookup in QWeb to
-find a template with the component name (or one of its ancestor).
+find a template with the component name (or one of its ancestors).
 
 ### Reactive system
 
-OWL components can be made reactive by observing some part of their state. See the [hooks](hooks.md) section for more details.
+OWL components are normal javascript classes. So, changing a component internal
+state does nothing more:
 
-The main idea is that the `useState` hook generate a proxy version of an object
-(this is done by an [observer](observer.md)), which allows the component to
-react to any change.
+```js
+class Counter extends Component {
+  static template = xml`<div t-on-click="increment"><t t-esc="state.value"/></div>`;
+  state = { value: 0 };
 
-```javascript
-const { useState } = owl.hooks;
-
-class SomeComponent extends owl.Component {
-  state = useState({ a: 0, b: 1 });
+  increment() {
+    this.state.value++;
+  }
 }
 ```
 
-Note that there is an important limitation: hooks need to be called in the
-constructor.
+Clicking on the `Counter` component defined above will call the `increment`
+method, but it will not rerender the component. To fix that, one could add an
+explicit call to `render` in `increment`:
+
+```js
+    increment() {
+        this.state.value++;
+        this.render();
+    }
+```
+
+However, it may be simple in this case, but it quickly become cumbersome, as a
+component get more complex, and its internal state is modified by more than one
+method.
+
+A better way is to use the reactive system: by using the `useState` hook (see the
+[hooks](hooks.md) section for more details), one can make Owl react to state
+changes. The `useState` hook generates a proxy version of an object
+(this is done by an [observer](observer.md)), which allows the component to
+react to any change. So, the `Counter` example above can be improved like this:
+
+```js
+const { useState } = owl.hooks;
+
+class Counter extends Component {
+  static template = xml`<div t-on-click="increment"><t t-esc="state.value"/></div>`;
+  state = useState({ value: 0 });
+
+  increment() {
+    this.state.value++;
+  }
+}
+```
+
+Obviously, we can call the `useState` hook more than once:
+
+```js
+const { useState } = owl.hooks;
+
+class Counter extends Component {
+  static template = xml`
+      <div>
+        <span t-on-click="increment(counter1)"><t t-esc="counter1.value"/></span>
+        <span t-on-click="increment(counter2)"><t t-esc="counter2.value"/></span>
+      </div>`;
+  counter1 = useState({ value: 0 });
+  counter2 = useState({ value: 0 });
+
+  increment(counter) {
+    counter.value++;
+  }
+}
+```
+
+Note that hooks are subject to one important [rule](hooks.md#one-rule): they need
+to be called in the constructor.
 
 ### Properties
 
@@ -115,10 +169,23 @@ constructor.
 
 - **`env`** (Object): the component environment, which contains a QWeb instance.
 
-- **`props`** (Object): this is an object given (in the constructor) by the parent
-  to configure the component. It can be dynamically changed later by the parent,
-  in some case. Note that `props` are owned by the parent, not by the component.
-  As such, it should not ever be modified by the component!!
+- **`props`** (Object): this is an object containing all the properties given by
+  the parent to a child component. For example, in the following situation,
+  the parent component gives a `user` and a `color` value to the `ChildComponent`.
+
+  ```xml
+    <div>
+      <ChildComponent user="state.user" color="color">
+    </div>
+  ```
+
+  Note that `props` are owned by the parent, not by the component.
+  As such, it should not ever be modified by the component (otherwise you risk
+  unintended effects, since the parent may not be aware of the change)!!
+
+  The `props` can be modified dynamically by the parent. In that case, the
+  component will go through the following lifecycle methods: `willUpdateProps`,
+  `willPatch` and `patched`.
 
 ### Static Properties
 
@@ -182,7 +249,7 @@ We explain here all the public methods of the `Component` class.
   we know that its state (or something in the environment, or ...) has changed.
   In that case, it should simply set to `true`.
 
-- **`unmount()`**: in case a component need to be detached/removed from the DOM, this
+- **`unmount()`**: in case a component needs to be detached/removed from the DOM, this
   method can be used. Most applications should not call `unmount`, this is more
   useful to the underlying component system.
 
@@ -303,8 +370,8 @@ will slightly slow down the component.
 #### `willUpdateProps(nextProps)`
 
 The willUpdateProps is an asynchronous hook, called just before new props
-are set. This is useful if the component needs some asynchronous task
-performed, depending on the props (for example, assuming that the props are
+are set. This is useful if the component needs to perform an asynchronous task,
+depending on the props (for example, assuming that the props are
 some record Id, fetching the record data).
 
 ```javascript
@@ -319,7 +386,7 @@ and performs a similar job).
 #### `willPatch()`
 
 The willPatch hook is called just before the DOM patching process starts.
-It is not called on the initial render. This is useful to read some
+It is not called on the initial render. This is useful to read
 information from the DOM. For example, the current position of the
 scrollbar.
 
@@ -338,15 +405,15 @@ with the DOM (for example, through an external library) whenever the
 component was patched. Note that this hook will not be called if the compoent is
 not in the DOM (this can happen with components with `t-keepalive`).
 
-Updating the compoent state in this hook is possible, but not encouraged.
-One need to be careful, because updates here will cause rerender, which in
-turn will cause other calls to patched. So, we need to be particularly
+Updating the component state in this hook is possible, but not encouraged.
+One needs to be careful, because updates here will create an additional rendering, which in
+turn will cause other calls to the `patched` method. So, we need to be particularly
 careful at avoiding endless cycles.
 
 #### `willUnmount()`
 
 willUnmount is a hook that is called each time just before a component is unmounted from
-the DOM. This is a good place to remove some listeners, for example.
+the DOM. This is a good place to remove listeners, for example.
 
 ```javascript
   mounted() {
@@ -363,7 +430,7 @@ This is the opposite method of `mounted`.
 
 The `catchError` method is useful when we need to intercept and properly react
 to (rendering) errors that occur in some sub components. See the section on
-[error handling](#error-handling)
+[error handling](#error-handling).
 
 ### Root Component
 
@@ -374,7 +441,7 @@ of an Owl application has to be created manually:
 ```js
 class App extends owl.Component { ... }
 
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES });
 const env = { qweb: qweb };
 const app = new App(env);
 app.mount(document.body);
@@ -472,7 +539,7 @@ constructor. This will be assigned to the `props` variable, which can be accesse
 on the component (and also, in the template). Whenever the state is updated, then
 the sub component will also be updated automatically.
 
-Note that there are some restrictions on prop names: `class`, `style` and any
+Note that there are restrictions on valid prop names: `class`, `style` and any
 string which starts with `t-` are not allowed.
 
 It is not common, but sometimes we need a dynamic component name and/or dynamic props. In this case,
@@ -531,7 +598,7 @@ class App extends Component<any, any, any> {
 In this example, the component `App` selects dynamically the concrete sub
 component class.
 
-**CSS and style:** there is some specific support to allow the parent to declare
+**CSS and style:** Owl allows the parent to declare
 additional css classes or style for the sub component: css declared in `class`, `style`, `t-att-class` or `t-att-style` will be added to the
 root component element.
 
@@ -544,7 +611,7 @@ root component element.
 Warning: there is a small caveat with dynamic class attributes: since Owl needs
 to be able to add/remove proper classes whenever necessary, it needs to be aware
 of the possible classes. Otherwise, it will not be able to make the difference
-between a valid css class added by the component, or some custom code, and a
+between a valid css class added by the component, or other custom code, and a
 class that need to be removed. This is why we only support the explicit syntax
 with a class object:
 
@@ -554,7 +621,7 @@ with a class object:
 
 ### Event Handling
 
-In a component's template, it is useful to be able to register handlers on some
+In a component's template, it is useful to be able to register handlers on DOM
 elements to some specific events. This is what makes a template _alive_. There
 are four different use cases.
 
@@ -610,6 +677,30 @@ to event `menu-loaded` will receive the payload in its `someMethod` handler
 
 By convention, we use KebabCase for the name of _business_ events.
 
+The `t-on` directive allows to prebind its arguments. For example,
+
+```xml
+<button t-on-click="someMethod(expr)">Do something</button>
+```
+
+Here, `expr` is a valid Owl expression, so it could be `true` or some variable
+from the rendering context.
+
+One can also directly specify inline statements. For example,
+
+```xml
+<button t-on-click="state.counter++">Increment counter</button>
+```
+
+Here, `state` must be defined in the rendering context (typically the component)
+as it will be translated to:
+
+```js
+button.addEventListener("click", () => {
+  component.state.counter++;
+});
+```
+
 In order to remove the DOM event details from the event handlers (like calls to
 `event.preventDefault`) and let them focus on data logic, _modifiers_ can be
 specified as additional suffixes of the `t-on` directive.
@@ -629,14 +720,14 @@ the order may matter. For instance `t-on-click.prevent.self` will prevent all
 clicks while `t-on-click.self.prevent` will only prevent clicks on the element
 itself.
 
-The `t-on` directive also allows to prebind some arguments. For example,
+Finally, empty handlers are tolerated as they could be defined only to apply
+modifiers. For example,
 
 ```xml
-<button t-on-click="someMethod(expr)">Do something</button>
+<button t-on-click.stop="">Do something</button>
 ```
 
-Here, `expr` is a valid Owl expression, so it could be `true` or some variable
-from the rendering context.
+This will simply stop the propagation of the event.
 
 ### Form Input Bindings
 
@@ -712,12 +803,12 @@ The `t-model` directive works with `<input>`, `<input type="checkbox">`,
 </div>
 ```
 
-Like event handling, the `t-model` directive accepts some modifiers:
+Like event handling, the `t-model` directive accepts the following modifiers:
 
 | Modifier  | Description                                                          |
 | --------- | -------------------------------------------------------------------- |
 | `.lazy`   | update the value on the `change` event (default is on `input` event) |
-| `.number` | tries to parse the value to a number (using `parseFloat`)            |
+| `.number` | try to parse the value to a number (using `parseFloat`)              |
 | `.trim`   | trim the resulting value                                             |
 
 For example:
@@ -733,27 +824,67 @@ Note: the online playground has an example to show how it works.
 
 ### `t-key` Directive
 
-Even though Owl tries to be as declarative as possible, some DOM state is still
-locked inside the DOM: for example, the scrolling state, the current user selection,
-the focused element or the state of an input. This is why we use a virtual dom
-algorithm to keep the actual DOM node as much as possible. However, this is
-sometimes not enough, and we need to help Owl decide if an element is actually
-the same, or is different. The `t-key` directive is used to give an identity to an element.
+Even though Owl tries to be as declarative as possible, the DOM does not fully
+expose its state declaratively in the DOM tree. For example, the scrolling state,
+the current user selection, the focused element or the state of an input are not
+set as attribute in the DOM tree. This is why we use a virtual dom
+algorithm to keep the actual DOM node as much as possible.
 
-There are three main use cases:
+However, in some situations, this is not enough, and we need to help Owl decide
+if an element is actually the same, or is a different element with the same
+properties.
 
-- _elements in a list_:
+Consider the following situation: we have a list of two items `[{text: "a"}, {text: "b"}]`
+and we render them in this template:
 
-  ```xml
-    <span t-foreach="todos" t-as="todo" t-key="todo.id">
-        <t t-esc="todo.text" />
-    </span>
-  ```
+```xml
+<p t-foreach="items" t-as="item"><t t-esc="item.text"/></p>
+```
 
-- _`t-if`/`t-else`_
+The result will be two `<p>` tags with text `a` and `b`. Now, if we swap them,
+and rerender the template, Owl needs to know what the intent is:
 
-- _animations_: give a different identity to a component. Ex: thread id with
-  animations on add/remove message.
+- should Owl actually swap the DOM nodes,
+- or should it keep the DOM nodes, but with an updated text content?
+
+This might look trivial, but it actually matters. These two possibilities lead
+to different results in some cases. For example, if the user selected the text
+of the first `p`, swapping them will keep the selection while updating the
+text content will not.
+
+There are many other cases where this is important: `input` tags with their
+value, css classes and animations, scroll position...
+
+So, the `t-key` directive is used to give an identity to an element. It allows
+Owl to understand if different elements of a list are actually different or not.
+
+The above example could be modified by adding an ID: `[{id: 1, text: "a"}, {id: 2, text: "b"}]`.
+Then, the template could look like this:
+
+```xml
+<p t-foreach="items" t-as="item" t-key="item.id"><t t-esc="item.text"/></p>
+```
+
+The `t-key` directive is useful for lists (`t-foreach`). A key should be
+a unique number or string (objects will not work: they will be cast to the
+`"[object Object]"` string, which is obviously not unique).
+
+Also, the key can be set on a `t` tag or on its children. The following variations
+are all equivalent:
+
+```xml
+<p t-foreach="items" t-as="item" t-key="item.id">
+  <t t-esc="item.text"/>
+</p>
+
+<t t-foreach="items" t-as="item" t-key="item.id">
+  <p t-esc="item.text"/>
+</t>
+
+<t t-foreach="items" t-as="item">
+  <p t-key="item.id" t-esc="item.text"/>
+</t>
+```
 
 ### Semantics
 
@@ -847,7 +978,7 @@ Here is what Owl will do:
 As an application becomes complex, it may be quite unsafe to define props in an informal way. This leads to two issues:
 
 - hard to tell how a component should be used, by looking at its code.
-- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parent.
+- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parents.
 
 A props type system would solve both issues, by describing the types and shapes
 of the props. Here is how it works in Owl:
@@ -855,7 +986,7 @@ of the props. Here is how it works in Owl:
 - `props` key is a static key (so, different from `this.props` in a component instance)
 - it is optional: it is ok for a component to not define a `props` key.
 - props are validated whenever a component is created/updated
-- props are only validated in `dev` mode (see [tooling page](tooling.md#development-mode))
+- props are only validated in `dev` mode (see [tooling page](../tooling.md#development-mode))
 - if a key does not match the description, an error is thrown
 - it validates keys defined in (static) `props`. Additional keys given by the
   parent will cause an error.
@@ -1072,9 +1203,9 @@ Here are a few tips on how to work with asynchronous components:
    synchronous renderings
 3. Lazy loading external libraries is a good use case for async rendering. This
    is mostly fine, because we can assume that it will only takes a fraction of a
-   second, and only once (see `owl.utils.loadJS`)
-4. For all the other cases, the `t-asyncroot` directive (to use alongside
-   `t-component`) is there to help you. When this directive is met, a new rendering
+   second, and only once (see [`owl.utils.loadJS`](utils.md#loadjs))
+4. For all the other cases, the [`AsyncRoot`](misc.md#asyncroot) component is there to help you. When
+   this component is met, a new rendering
    sub tree is created, such that the rendering of that component (and its
    children) is not tied to the rendering of the rest of the interface. It can
    be used on an asynchronous component, to prevent it from delaying the
@@ -1086,7 +1217,9 @@ Here are a few tips on how to work with asynchronous components:
    ```xml
    <div t-name="ParentComponent">
      <SyncChild />
-     <AsyncChild t-asyncroot="1"/>
+     <AsyncRoot>
+        <AsyncChild/>
+     </AsyncRoot>
    </div>
    ```
 
@@ -1103,7 +1236,7 @@ from lifecycle hooks): the `catchError` hook.
 
 Whenever the `catchError` lifecycle hook is implemented, all errors coming from
 sub components rendering and/or lifecycle method calls will be caught and given
-to the `catchError` method. This allow us to properly handle the error, and to
+to the `catchError` method. This allows us to properly handle the error, and to
 not break the application.
 
 For example, here is how we could implement an `ErrorBoundary` component:

doc/reference/context.md

@@ -11,7 +11,7 @@
 ## Overview
 
 The `Context` object provides a way to share data between an arbitrary number
-of component. Usually, data is passed from a parent to its children component,
+of components. Usually, data is passed from a parent to its children component,
 but when we have to deal with some mostly global information, this can be
 annoying, since each component will need to pass the information to each children,
 even though some or most of them will not use the information.
@@ -29,7 +29,7 @@ context, and add it to the environment:
 ```js
 const deviceContext = new Context({ isMobile: true });
 const env = {
-  qweb: new QWeb(TEMPLATES),
+  qweb: new QWeb({ templates: TEMPLATES }),
   deviceContext
 };
 ```

doc/reference/hooks.md

@@ -35,7 +35,7 @@ Owl hooks serve the same purpose, except that they work for class components
 there seems to be the misconception that hooks are in opposition to class. This
 is clearly not true, as shown by Owl hooks).
 
-Hooks works beautifully with Owl components: they solve the problems mentioned
+Hooks work beautifully with Owl components: they solve the problems mentioned
 above, and in particular, they are the perfect way to make your component
 reactive.
 
@@ -127,7 +127,7 @@ class SomeComponent extends Component {
 
 ### One rule
 
-There is only one rule: every hook for a component have to be called in the
+There is only one rule: every hook for a component has to be called in the
 constructor (or in class fields):
 
 ```js
@@ -152,14 +152,14 @@ class SomeComponent extends Component {
 }
 ```
 
-Hooks can get a reference to the currently being defined component with the
-`Component.current` static property. This is why they need to be called in the
-constructor.
+In a hook, the `Component.current` static property is the reference to the
+component instance that is currently being created. Hooks need to be called in
+the constructor to ensure that this reference is properly set.
 
 ### `useState`
 
-The `useState` hook is certainly the most important hooks for Owl components:
-this is what enables component to be reactive, to react to state change.
+The `useState` hook is certainly the most important hook for Owl components:
+this is what allows a component to be reactive, to react to state change.
 
 The `useState` hook has to be given an object or an array, and will return
 an observed version of it (using a `Proxy`).
@@ -181,27 +181,30 @@ class Counter extends owl.Component {
 }
 ```
 
+It is important to remember that `useState` only works with objects or arrays. It
+is necessary, since Owl needs to react to a change in state.
+
 ### `onMounted`
 
-`onMounted` is not an user hook, but is a building block designed to help make useful
+`onMounted` is not a user hook, but is a building block designed to help make useful
 abstractions. `onMounted` registers a callback, which will be called when the component
 is mounted (see example on top of this page).
 
 ### `onWillUnmount`
 
-`onWillUnmount` is not an user hook, but is a building block designed to help make useful
+`onWillUnmount` is not a user hook, but is a building block designed to help make useful
 abstractions. `onWillUnmount` registers a callback, which will be called when the component
 is unmounted (see example on top of this page).
 
 ### `onWillPatch`
 
-`onWillPatch` is not an user hook, but is a building block designed to help make useful
+`onWillPatch` is not a user hook, but is a building block designed to help make useful
 abstractions. `onWillPatch` registers a callback, which will be called just
 before the component patched.
 
 ### `onPatched`
 
-`onPatched` is not an user hook, but is a building block designed to help make useful
+`onPatched` is not a user hook, but is a building block designed to help make useful
 abstractions. `onPatched` registers a callback, which will be called just
 after the component patched.
 
@@ -220,18 +223,18 @@ be ready whenever the component is rendered:
 
 ```js
 function useLoader() {
-    const component = Component.current;
-    const record = useState({});
-    onWillStart(async () => {
-        const recordId = component.props.id;
-        Object.assign(record, await fetchSomeRecord(recordId));
-    });
-    return record;
+  const component = Component.current;
+  const record = useState({});
+  onWillStart(async () => {
+    const recordId = component.props.id;
+    Object.assign(record, await fetchSomeRecord(recordId));
+  });
+  return record;
 }
 ```
 
 Note that this example does not update the record value whenever props are
-updated.  For that situation, we need to use the `onWillUpdateProps` hook.
+updated. For that situation, we need to use the `onWillUpdateProps` hook.
 
 ### `onWillUpdateProps`
 
@@ -241,17 +244,17 @@ useful to perform some asynchronous task such as fetching updated data.
 
 ```js
 function useLoader() {
-    const component = Component.current;
-    const record = useState({});
+  const component = Component.current;
+  const record = useState({});
 
-    async function updateRecord(id) {
-        Object.assign(record, await fetchSomeRecord(id));
-    }
+  async function updateRecord(id) {
+    Object.assign(record, await fetchSomeRecord(id));
+  }
 
-    onWillStart(() => updateRecord(component.props.id));
-    onWillUpdateProps(nextProps => updateRecord(nextProps.id));
+  onWillStart(() => updateRecord(component.props.id));
+  onWillUpdateProps(nextProps => updateRecord(nextProps.id));
 
-    return record;
+  return record;
 }
 ```
 
@@ -305,7 +308,7 @@ The `t-ref` directive also accepts dynamic values with string interpolation
 <div t-ref="component_{{someCondition ? '1' : '2'}}"/>
 ```
 
-Here, the references needs to be set like this:
+Here, the references need to be set like this:
 
 ```js
 this.ref1 = useRef("component_1");
@@ -321,8 +324,8 @@ The environment is sometimes useful to share some common information between
 all components. But sometimes, we want to _scope_ that knowledge to a subtree.
 
 For example, if we have a form view component, maybe we would like to make some
-`model` object available to all sub component, but not to the whole application.
-This is where the `useSubEnv` hook may be useful: it let a component add some
+`model` object available to all sub components, but not to the whole application.
+This is where the `useSubEnv` hook may be useful: it lets a component add some
 information to the environment in a way that only the component and its children
 can access it:
 
@@ -359,39 +362,39 @@ getters. See the [store documentation](store.md) for more information.
 ### Making customized hooks
 
 Hooks are a wonderful way to organize the code of a complex component by feature
-instead of by lifecycle methods.  They are like mixins, except that they can be
+instead of by lifecycle methods. They are like mixins, except that they can be
 easily composed together.
 
 But, like every good things in life, hooks should be used with moderation. They are
 not the solution to every problem.
 
 - they may be overkill: if your component needs to perform some action specific
-  to him (so, the specific code does not need to be shared), there is nothing
+  to itself (so, the specific code does not need to be shared), there is nothing
   wrong with a simple class method:
 
   ```js
   // maybe overkill
   class A extends Component {
     constructor(...args) {
-        super(...args);
-        useMySpecificHook()
+      super(...args);
+      useMySpecificHook();
     }
   }
 
   // ok
   class B extends Component {
     constructor(...args) {
-        super(...args);
-        this.performSpecificTask()
+      super(...args);
+      this.performSpecificTask();
     }
   }
   ```
 
   Note that the second solution is easier to extend in sub components.
 
-- they may be harder to test: if a customized hook inject some external side
+- they may be harder to test: if a customized hook injects some external side
   effect dependency, then it is harder to test without doing some non obvious
-  manipulation.  For example, assume that we want to give a reference to a
+  manipulation. For example, assume that we want to give a reference to a
   router in a `useRouter` hook. We could do this:
 
   ```js
@@ -402,7 +405,7 @@ not the solution to every problem.
   }
   ```
 
-  As you can see, this does not *hook* into the internal of the component. It
+  As you can see, this does not _hook_ into the internal of the component. It
   simply returns a global object, which is difficult to mock.
 
   A better way would be to do something like this: get the reference from the
@@ -410,7 +413,7 @@ not the solution to every problem.
 
   ```js
   function useRouter() {
-      return Component.current.env.router;
+    return Component.current.env.router;
   }
   ```
 

doc/reference/misc.md

@@ -0,0 +1,23 @@
+# 🦉 Miscellaneous 🦉
+
+## `AsyncRoot`
+
+When this component is used, a new rendering sub tree is created, such that the
+rendering of that component (and its children) is not tied to the rendering of
+the rest of the interface. It can be used on an asynchronous component, to
+prevent it from delaying the rendering of the whole interface, or on a
+synchronous one, such that its rendering isn't delayed by other (asynchronous)
+components. Note that this directive has no effect on the first rendering, but
+only on subsequent ones (triggered by state or props changes).
+
+```xml
+<div t-name="ParentComponent">
+  <SyncChild />
+  <AsyncRoot>
+     <AsyncChild/>
+  </AsyncRoot>
+</div>
+```
+
+The `AsyncRoot` assumes that there is exactly one root node inside it. It can
+be a dom node or a component.

doc/reference/observer.md

@@ -0,0 +1,52 @@
+# 🦉 Observer 🦉
+
+Owl needs to be able to react to state changes. For example, whenever the state
+of a component is changed, Owl needs to rerender it. To help with that, there is
+an Observer class. Its job is to observe the state of an object (or array), and
+to react to any change. The observer is implemented with the native `Proxy`
+object. Note that this means that it will not work on older browsers.
+
+Note that the `Observer` is used by the `useState` and `useContext` hooks. This
+is the way most Owl applications will create observers. For the majority of
+use cases, there is no need to directly instantiate an observer.
+
+## Example
+
+For example, this code will display `update` in the console:
+
+```javascript
+const observer = new owl.Observer();
+observer.notifyCB = () => console.log("update");
+const obj = observer.observe({ a: { b: 1 } });
+
+obj.a.b = 2;
+```
+
+This example shows that an observer can observe nested properties.
+
+## Reference
+
+**observe** An observer can observe multiple values with the `observe` method.
+This method takes an object or an array as its argument and will return a proxy
+(which is mapped to the initial object/array). With this proxy, the observer
+can detect whenever any internal value is changed.
+
+**Registering a callback** Whenever an observer sees a state change, it will
+call its `notifyCB` method. No additional information is given to the callback.
+
+**deepRevNumber** Each observed value has an internal revision number, which
+is incremented every time the value is observed. Sometimes, it can be useful
+to obtain that number:
+
+```js
+const observer = new owl.Observer();
+const obj = observer.observe({ a: { b: 1 } });
+
+observer.deepRevNumber(obj.a); // 1
+obj.a.b = 2;
+
+observer.deepRevNumber(obj.a); // 2
+```
+
+The `deepRevNumber` can also return 0, which indicates that the value is not
+observed.

doc/reference/qweb.md

@@ -16,11 +16,12 @@
   - [Dynamic Attributes](#dynamic-attributes)
   - [Loops](#loops)
   - [Rendering Sub Templates](#rendering-sub-templates)
+  - [Translations](#translations)
   - [Debugging](#debugging)
 
 ## Overview
 
-[QWeb](https://www.odoo.com/documentation/12.0/reference/qweb.html) is the primary templating engine used by Odoo. It is based on the XML format, and used
+[QWeb](https://www.odoo.com/documentation/13.0/reference/qweb.html) is the primary templating engine used by Odoo. It is based on the XML format, and used
 mostly to generate HTML. In OWL, QWeb templates are compiled into functions that
 generate a virtual dom representation of the HTML.
 
@@ -33,7 +34,7 @@ To avoid element rendering, a placeholder element `<t>` is also available, which
     <span t-if="somecondition">Some string</span>
     <ul t-else="1">
         <li t-foreach="messages" t-as="message">
-            <t t-esc="message">
+            <t t-esc="message"/>
         </li>
     </ul>
 </div>
@@ -60,6 +61,7 @@ We present here a list of all standard QWeb directives:
 | `t-att`, `t-attf-*`, `t-att-*` | [Dynamic attributes](#dynamic-attributes)                    |
 | `t-call`                       | [Rendering sub templates](#rendering-sub-templates)          |
 | `t-debug`, `t-log`             | [Debugging](#debugging)                                      |
+| `t-translation`                | [Disabling the translation of a node](#translations)         |
 | `t-name`                       | [Defining a template (not really a directive)](#qweb-engine) |
 
 The component system in Owl requires additional directives, to express various
@@ -85,13 +87,16 @@ instantiated:
 const qweb = new owl.QWeb();
 ```
 
-It's API is quite simple:
+Its API is quite simple:
 
-- **`constructor(data)`**: constructor. Takes an optional string to add initial
-  templates (see `addTemplates` for more information on format of the string).
+- **`constructor(config)`**: constructor. Takes an optional configuration object
+  with an optional `templates` string to add initial
+  templates (see `addTemplates` for more information on format of the string)
+  and an optional `translateFn` translate function (see the section on
+  [translations](#translations)).
 
   ```js
-  const qweb = new owl.QWeb(TEMPLATES);
+  const qweb = new owl.QWeb({ templates: TEMPLATES, translateFn: _t });
   ```
 
 - **`addTemplate(name, xmlStr, allowDuplicate)`**: add a specific template.
@@ -100,7 +105,8 @@ It's API is quite simple:
   qweb.addTemplate("mytemplate", "<div>hello</div>");
   ```
 
-  If the optional `allowDuplicate` is set to `true`, then `QWeb` will simply return whenever a template is added for a second time. Otherwise, `QWeb` will crash.
+  If the optional `allowDuplicate` is set to `true`, then `QWeb` will simply
+  ignore templates added for a second time. Otherwise, `QWeb` will crash.
 
 - **`addTemplates(xmlStr)`**: add a list of templates (identified by `t-name`
   attribute).
@@ -115,7 +121,7 @@ It's API is quite simple:
   ```
 
 - **`render(name, context, extra)`**: renders a template. This returns a `vnode`,
-  which is a virtual representation of the DOM (see [vdom doc](vdom.md)).
+  which is a virtual representation of the DOM (see [vdom doc](../architecture/vdom.md)).
 
   ```js
   const vnode = qweb.render("App", component);
@@ -128,13 +134,13 @@ It's API is quite simple:
   const str = qweb.renderToString("someTemplate", somecontext);
   ```
 
-- **`registerTemplate(name, template)`**: static function to register an global
+- **`registerTemplate(name, template)`**: static function to register a global
   QWeb template. This is useful for commonly used components accross the
   application, and for making a template available to an application without
   having a reference to the actual QWeb instance.
 
   ```js
-  QWeb.registerTemplate("mytemplate", `<div>some template`);
+  QWeb.registerTemplate("mytemplate", `<div>some template</div>`);
   ```
 
 - **`registerComponent(name, Component)`**: static function to register an OWL Component
@@ -154,7 +160,7 @@ It's API is quite simple:
 
 In some way, a `QWeb` instance is the core of an Owl application. It is the only
 mandatory element of an [environment](component.md#environment). As such, it
-has an extra responsability: it can act as an event bus for internal communication
+has an extra responsibility: it can act as an event bus for internal communication
 between Owl classes. This is the reason why `QWeb` actually extends [EventBus](event_bus.md).
 
 ## Reference
@@ -165,7 +171,7 @@ specific extensions are documented in various other parts of the documentation.
 
 ### White Spaces
 
-White spaces in a templates are handled in a special way:
+White spaces in a template are handled in a special way:
 
 - consecutive whitespaces are always condensed to a single whitespace
 - if a whitespace-only text node contains a linebreak, it is ignored
@@ -200,14 +206,14 @@ root nodes.
 ### Expression Evaluation
 
 QWeb expressions are strings that will be processed at compile time. Each variable in
-the javascript expression will be replaced by a lookup in the context (so, the
+the javascript expression will be replaced with a lookup in the context (so, the
 component). For example, `a + b.c(d)` will be converted into:
 
 ```js
 context["a"] + context["b"].c(context["d"]);
 ```
 
-It is useful to explain the various rules that applies on these expressions:
+It is useful to explain the various rules that apply on these expressions:
 
 1. it should be a simple expression which returns a value. It cannot be a statement.
 
@@ -233,14 +239,14 @@ It is useful to explain the various rules that applies on these expressions:
 3. it can use a few special operators to avoid using symbols such as `<`, `>`,
    `&` or `|`. This is useful to make sure that we still write valid XML.
 
-   | Word  | will be replaced by |
-   | ----- | ------------------- |
-   | `and` | `&&`                |
-   | `or`  | `\|\|`              |
-   | `gt`  | `>`                 |
-   | `gte` | `>=`                |
-   | `lt`  | `<`                 |
-   | `lte` | `<=`                |
+   | Word  | replaced with |
+   | ----- | ------------- |
+   | `and` | `&&`          |
+   | `or`  | `\|\|`        |
+   | `gt`  | `>`           |
+   | `gte` | `>=`          |
+   | `lt`  | `<`           |
+   | `lte` | `<=`          |
 
    So, one can write this:
 
@@ -389,14 +395,25 @@ If an expression evaluates to a falsy value, it will not be set at all:
 <div t-att-foo="false"/>  <!-- result: <div></div> -->
 ```
 
-There is another way to format a string attribute: the `t-attf-` directive. With
-it, you get string interpolation:
+It is sometimes convenient to format an attribute with string interpolation. In
+that case, the `t-attf-` directive can be used. It is useful when we need to mix
+literal and dynamic elements, such as css classes.
 
 ```xml
 <div t-attf-foo="a {{value1}} is {{value2}} of {{value3}} ]"/>
 <!-- result if values are set to 1,2 and 3: <div foo="a 0 is 1 of 2 ]"></div> -->
 ```
 
+If we need completely dynamic attribute names, then there is an additional
+directive: `t-att`, which takes either an object (with keys mapping to their
+values) or a pair `[key, value]`. For example:
+
+```xml
+<div t-att="{'a': 1, 'b': 2}"/> <!-- result: <div a="1" b="2"></div> -->
+
+<div t-att="['a', 'b']"/> <!-- <div a="b"></div> -->
+```
+
 ### Loops
 
 QWeb has an iteration directive `t-foreach` which take an expression returning the
@@ -431,7 +448,7 @@ is equivalent to the previous example.
 or an object (the current item will be the current key).
 
 In addition to the name passed via t-as, `t-foreach` provides a few other
-variables for various data points (note: `$as` will be replaced by the name
+variables for various data points (note: `$as` will be replaced with the name
 passed to `t-as`):
 
 - `$as_value`: the current iteration value, identical to `$as` for lists and
@@ -449,19 +466,33 @@ the context of the `t-foreach`, the value is copied at the end of the foreach
 into the global context.
 
 ```xml
-<t t-set="existing_variable" t-value="False"/>
+<t t-set="existing_variable" t-value="false"/>
 <!-- existing_variable now False -->
 
 <p t-foreach="Array(3)" t-as="i">
-    <t t-set="existing_variable" t-value="True"/>
-    <t t-set="new_variable" t-value="True"/>
-    <!-- existing_variable and new_variable now True -->
+    <t t-set="existing_variable" t-value="true"/>
+    <t t-set="new_variable" t-value="true"/>
+    <!-- existing_variable and new_variable now true -->
 </p>
 
-<!-- existing_variable always True -->
+<!-- existing_variable always true -->
 <!-- new_variable undefined -->
 ```
 
+Owl QWeb is used as the template engine for components. Components are frequently
+updated, and reuse as much of the previous DOM as possible. Loops offer a specific
+problem for this usecase: how does the template engine know if two rows have
+been swapped, or if the content of these rows was changed? To help Owl with that,
+there is an additional directive: [`t-key`](component.md#t-key-directive).
+
+```xml
+<p t-foreach="state.things" t-as="thing" t-key="thing.id">
+    <t t-esc="thing.content"/>
+</p>
+```
+
+If there is no `t-key` directive, Owl will use the index as a default key.
+
 ### Rendering Sub Templates
 
 QWeb templates can be used for top level rendering, but they can also be used
@@ -510,6 +541,53 @@ will result in :
 </div>
 ```
 
+### Translations
+
+If properly setup, Owl QWeb engine can translate all rendered templates. To do
+so, it needs a translate function, which takes a string and returns a string.
+
+For example:
+
+```js
+const translations = {
+  hello: "bonjour",
+  yes: "oui",
+  no: "non"
+};
+const translateFn = str => translations[str] || str;
+
+const qweb = new QWeb({ translateFn });
+```
+
+Once setup, all rendered templates will be translated using `translateFn`:
+
+- each text node will be replaced with its translation,
+- each of the following attribute values will be translated as well: `title`,
+  `placeholder`, `label` and `alt`,
+- translating text nodes can be disabled with the special attribute `t-translation`,
+  if its value is `off`.
+
+So, with the above `translateFn`, the following templates:
+
+```xml
+<div>hello</div>
+<div t-translation="off">hello</div>
+<div>Are you sure?</div>
+<input placeholder="hello" other="yes"/>
+```
+
+will be rendered as:
+
+```xml
+<div>bonjour</div>
+<div>hello</div>
+<div>Are you sure?</div>
+<input placeholder="bonjour" other="yes"/>
+```
+
+Note that the translation is done during the compilation of the template, not
+when it is rendered.
+
 ### Debugging
 
 The javascript QWeb implementation provides two useful debugging directives:
@@ -531,4 +609,4 @@ will stop execution if the browser dev tools are open.
 <t t-log="foo"/>
 ```
 
-will print 42 to the console
+will print 42 to the console.

doc/reference/router.md

@@ -97,6 +97,13 @@ The `Router` constructor takes three arguments:
 - an optional object (with the only key `mode` which can be `history` (default
   value) or `hash`).
 
+`history` will use the browser [History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API) as the mechanism to manage URL.\
+Example: `https://yourdomain.tld/my_custom_route`.\
+For this mechanism to work, you need a way to configure your web server accordingly.
+
+`hash` will manipulate the hash of the URL.\
+Example: `https://yourdomain.tld/index.html#/my_custom_route`.
+
 ```js
 const ROUTES = [...];
 const router = new owl.router.Router(env, ROUTES, {mode: 'history'});

doc/reference/store.md

@@ -10,6 +10,8 @@
   - [Getters](#getters)
   - [Connecting a Component](#connecting-a-component)
   - [`useStore`](#usestore)
+  - [`useDispatch`](#usedispatch)
+  - [`useGetters`](#usegetters)
   - [Semantics](#semantics)
   - [Good Practices](#good-practices)
 
@@ -17,12 +19,12 @@
 
 Managing the state in an application is not an easy task. In some cases, the
 state of an application can be part of the component tree, in a natural way.
-However, there are situations where some part of the state need to be displayed
+However, there are situations where some parts of the state need to be displayed
 in various parts of the user interface, and then, it is not obvious which
 component should own which part of the state.
 
 Owl's solution to this issue is a centralized store. It is a class that owns
-some (or all) state, and let the developer update it in a structured way, with
+some (or all) state, and lets the developer update it in a structured way, with
 `actions`. Owl components can then connect to the store, and will be updated if
 necessary.
 
@@ -113,9 +115,10 @@ const actions = {
 ```
 
 The first argument to an action method is an object with four keys:
+
 - `state`: the current state of the store content,
 - `dispatch`: a function that can be used to dispatch other actions,
-- `getters`: an object containing all getters defined in the store
+- `getters`: an object containing all getters defined in the store,
 - `env`: the current environment. This is useful sometimes, in particular if
   an action needs to apply some side effects (such as performing an rpc), and
   the `rpc` method is located in the environment.
@@ -132,7 +135,7 @@ call.
 
 Also, it is important to be aware that we need to be careful with asynchronous
 logic. Each state change will potentially trigger a rerendering, so we need to
-make sure that we do not have a partial corrupted state. Here is an example that
+make sure that we do not have a partially corrupted state. Here is an example that
 is likely not a good idea:
 
 ```javascript
@@ -185,7 +188,7 @@ transform the data contained in the store.
 const getters = {
   getPost({ state }, id) {
     const post = state.posts.find(p => p.id === id);
-    const author = state.authors.find(a => (a.id = post.id));
+    const author = state.authors.find(a => a.id === post.id);
     return {
       id,
       author,
@@ -200,18 +203,16 @@ const post = store.getters.getPost(id);
 
 Getters take _at most_ one argument.
 
-Note that getters are cached if they don't take any argument, or their argument
-is a string or a number.
+Note that getters are not cached.
 
 ### Connecting a Component
 
 At some point, we need a way to interact with the store from a component. This
 can be done with the help of the three store hooks:
 
-- `useStore` to subscribe a component to some part of the store state,
-- `useDispatch` to get a reference to a dispatch function
-- `useGetters` to get a reference to the getters defined in the store.
-
+- [`useStore`](#usestore) to subscribe a component to some part of the store state,
+- [`useDispatch`](#usedispatch) to get a reference to a dispatch function,
+- [`useGetters`](#usegetters) to get a reference to the getters defined in the store.
 
 Assume we have this store:
 
@@ -223,7 +224,7 @@ const actions = {
 };
 
 const state = {
-  counter: {value: 0}
+  counter: { value: 0 }
 };
 const store = new owl.Store({ state, actions });
 ```
@@ -245,46 +246,81 @@ const counter = new Counter({ store, qweb });
 </button>
 ```
 
-### `useStore``
+### `useStore`
 
 The `useStore` hook is used to select some part of the store state. It accepts
 two arguments:
 
 - a selector function, which takes the store state as first argument (and the
   component props as second argument) and returns
-  an object or an array (which will be then observed)
+  an object or an array (which will be then observed),
 - optionally, an object with a `store` key (if we want to override the default
-  store) and an equality function (if we want to specialize the comparison)
-
+  store) and an equality function (if we want to specialize the comparison).
 
 If the `useStore` callback selects a sub part of the store state, the component
 will only be rerendered whenever this part of the state changes. Otherwise, it
-will perform a strict equality check and updates the component every time this
+will perform a strict equality check and will update the component every time this
 check fails.
 
+Also, it may not be obvious, but it is crucial to remember that the selector
+function should return an object or an array.  The reason is that it needs to be
+observed, otherwise the component would not be able to react to changes.
+
+### `useDispatch`
+
+The `useDispatch` hook is useful when a component needs to be able to dispatch
+actions. It takes an optional argument, which is a store. If not given, it will
+use the store in the environment.
+
+Note that a component does not need to be connected in any other way to the store.
+For example:
+
+```js
+class DoSomethingButton extends Component {
+  static template = xml`<button t-on-click="dispatch('something')">Click</button>`;
+  dispatch = useDispatch();
+}
+```
+
+### `useGetters`
+
+The `useGetters` hook is useful when a component needs to be able to use the
+getters defined in a store. It takes an optional argument, which is a store. If
+not given, it will use the store in the environment.
+
+Note that a component does not need to be connected in any other way to the store.
+For example:
+
+```js
+class InfoButton extends Component {
+  static template = xml`<span><t t-esc="getters.somevalue()"></span>`;
+  getters = useGetters();
+}
+```
+
 ### Semantics
 
 The `Store` class and the `useStore` hook try to be smart and to optimize as much
 as possible the rendering and update process. What is important to know is:
 
 - components are always updated in the order of their creation (so, parent
-  before children)
-- they are updated only if they are in the DOM
+  before children),
+- they are updated only if they are in the DOM,
 - if a parent is asynchronous, the system will wait for it to complete its
-  update before updating other components.
+  update before updating other components,
 - in general, updates are not coordinated. This is not a problem for synchronous
   components, but if there are many asynchronous components, this could lead to
-  a situation where some part of the UI is updated and other parts of the UI is
+  a situation where some part of the UI is updated and some other part of the UI is
   not updated.
 
 ### Good Practices
 
 - avoid asynchronous components as much as possible. Asynchronous components
-  lead to situations where parts of the UI is not updated immediately.
+  lead to situations where parts of the UI is not updated immediately,
 - do not be afraid to connect many components, parent or children if needed. For
   example, a `MessageList` component could get a list of ids in its `useStore`
   call and a `Message` component could get the data of its own
-  message
+  message,
 - since the `useStore` function is called for each connected component,
   for each state update, it is important to make sure that these functions are
   as fast as possible.

doc/reference/tags.md

@@ -1,8 +1,15 @@
 # 🦉 Tags 🦉
 
-Tags are very small helper to make it easy to write inline templates. There is
+## Content
+
+- [Overview](#overview)
+- [`xml` tag](#xml-tag)
+
+## Overview
+
+Tags are very small helpers to make it easy to write inline templates. There is
 only one currently available tag: `xml`, but we plan to add other tags later,
-such as a `css` tag, which will be used to write single file components.
+such as a `css` tag, which will be used to write [single file components](../tooling.md#single-file-component).
 
 ## XML tag
 
@@ -31,8 +38,8 @@ With tags, this process is slightly simplified. The name is uniquely generated,
 and the template is automatically registered:
 
 ```js
-import { Component } from 'owl'
-import { xml } from 'owl/tags'
+const { Component } = owl;
+const { xml } = owl.tags;
 
 class MyComponent extends Component {
     static template = xml`

doc/reference/utils.md

@@ -0,0 +1,148 @@
+# 🦉 Utils 🦉
+
+Owl export a few useful utility functions, to help with common issues. Those
+functions are all available in the `owl.utils` namespace.
+
+## Content
+
+- [`whenReady`](#whenready): executing code when DOM is ready
+- [`loadJS`](#loadjs): loading script files
+- [`loadFile`](#loadfile): loading a file (useful for templates)
+- [`escape`](#escape): sanitizing strings
+- [`debounce`](#debounce): limiting rate of function calls
+- [`shallowEqual`](#shallowequal): shallow object comparison
+
+## `whenReady`
+
+The function `whenReady` returns a `Promise` resolved when the DOM is ready (if
+not ready yet, resolved directly otherwise). If called with a callback as
+argument, it executes it as soon as the DOM ready (or directly).
+
+```js
+Promise.all([loadFile("templates.xml"), owl.utils.whenReady()]).then(function([templates]) {
+  const qweb = new owl.QWeb({ templates });
+  const app = new App({ qweb });
+  app.mount(document.body);
+});
+```
+
+or alternatively:
+
+```js
+owl.utils.whenReady(function() {
+  const qweb = new owl.QWeb();
+  const app = new App({ qweb });
+  app.mount(document.body);
+});
+```
+
+## `loadJS`
+
+`loadJS` takes a url (string) for a javascript resource, and loads it (by adding
+a script tag in the document head). It returns a promise, so the caller can
+properly reacts when it is ready. Also, it is smart: it maintains a list of urls
+previously loaded (or currently being loaded), and prevent doing twice the work.
+
+For example, it is useful for lazy loading external libraries:
+
+```js
+class MyComponent extends owl.Component {
+  willStart() {
+    return owl.utils.loadJS("/static/libs/someLib.js");
+  }
+}
+```
+
+## `loadFile`
+
+`loadFile` is a helper function to fetch a file. It simply
+performs a `GET` request and returns the resulting string in a promise. The
+initial usecase for this function is to load a template file. For example:
+
+```js
+async function makeEnv() {
+  const templates = await owl.utils.loadFile("templates.xml");
+  const qweb = new owl.QWeb({ templates });
+  return { qweb };
+}
+```
+
+Note that unlike `loadJS`, this function returns the content of the file as a
+string. It does not add a `script` tag or any other side effect.
+
+## `escape`
+
+Sometimes, we need to display dynamic data (for example user-generated data) in
+the user interface. If this is done by a `QWeb` template, it is not an issue:
+
+```xml
+    <div><t t-esc="user.data"/></div>
+```
+
+The `QWeb` engine will create a `div` node and add the content of the `user.data`
+string as a text node, so the web browser will not parse it as html. However,
+it may be a problem if this is done with some javascript code like this:
+
+```js
+class BadComponent extends Component {
+  // some template with a ref to a div
+  // some code ...
+
+  mounted() {
+    this.divRef.el.innerHTML = this.state.value;
+  }
+}
+```
+
+In this case, the content of the `div` will be parsed as html, which may inject
+unwanted behaviour. To fix this, the `escape` function will simply transform a
+string into an escaped version of the same string, which will be properly displayed
+by the browser, but which will not be parsed as html (for example, `"<ok>"` is
+escaped to the string: `"&lt;ok&gt;"`). So, the bad example above can be fixed
+with the following change:
+
+```js
+this.divRef.el.innerHTML = owl.utils.escape(this.state.value);
+```
+
+## `debounce`
+
+The `debounce` function is useful when we want to limit the number of times some
+function/action is perfomed. For example, this may be useful to prevent issue
+with people double clicking on a button.
+
+It takes three arguments:
+
+- `func` (function): this is the function that will be rate limited
+- `wait` (number): this is the number of milliseconds that we want to use to
+  rate limit the function `func`
+- `immediate` (optional, boolean, default=false): if `immediate` is true, the
+  function will be triggered immediately (leading edge of the interval). If false,
+  the function will be triggered at the end (trailing edge).
+
+It returns a function. For example:
+
+```js
+const debounce = owl.utils.debounce;
+window.addEventListener("mousemove", debounce(doSomething, 100));
+```
+
+As this example shows, it is usualy useful for event handlers which are triggered
+very quickly, such as `scroll` or `mousemove` events.
+
+## `shallowEqual`
+
+This function checks if two objects have the same values assigned to each keys:
+
+```js
+shallowEqual({ a: 1, b: 2 }, { a: 1, b: 2 }); // true
+shallowEqual({ a: 1, b: 2 }, { a: 1, b: 3 }); // false
+```
+
+However, for performance reasons, it assumes that the two objects have the same
+keys. If we are in a situation where this is not guaranteed, the following code
+will work:
+
+```js
+const completeShallowEqual = (a, b) => shallowEqual(a, b) && shallowEqual(b, a);
+```

doc/tooling.md

@@ -60,12 +60,21 @@ useful to compare various performance metrics on some tasks.
 
 ## Single File Component
 
-If you want to have `xml` syntax highlighting while using the `xml` helper which
-helps you define inline templates, there is a VS Code addon `Comment tagged template`
-which, if installed, does exactly that. To enable it, you need to add a comment,
-like this:
+It is very useful to group code by feature instead of by type of file. It makes
+it easier to scale application to larger size.
+
+To do so, Owl currently has a small helper that makes it easy to define a
+template inside a javascript (or typescript) file: the [`xml`](reference/tags.md#xml-tag)
+helper. With this, a template is automatically registered to [QWeb](reference/qweb.md).
+
+This means that the template and the javascript code can be defined in the same
+file. It is not currently possible to add css to the same file, but Owl may
+get a `css` tag helper later.
 
 ```js
+const { Component } = owl;
+const { xml } = owl.tags;
+
 // -----------------------------------------------------------------------------
 // TEMPLATE
 // -----------------------------------------------------------------------------
@@ -85,3 +94,8 @@ class MyComponent extends Component {
   // rest of component...
 }
 ```
+
+Note that the above example has an inline xml comment, just after the `xml` call.
+This is useful for some editor plugins, such as the VS Code addon
+`Comment tagged template`, which, if installed, add syntax highlighting to the
+content of the template string.

doc/utils.md

@@ -1,63 +0,0 @@
-# 🦉 Utils 🦉
-
-Owl export a few useful utility functions, to help with common issues. Those
-functions are all available in the `owl.utils` namespace.
-
-## Content
-
-- [`whenReady`](#whenready): executing code when DOM is ready
-- [`loadJS`](#loadjs): loading script files
-- [`loadTemplates`](#loadtemplates): loading xml files
-- [`escape`](#escape): sanitizing strings
-- [`debounce`](#debounce): limiting rate of function calls
-
-## `whenReady`
-
-The function `whenReady` returns a `Promise` resolved when the DOM is ready (if
-not ready yet, resolved directly otherwise). If called with a callback as
-argument, it executes it as soon as the DOM ready (or directly).
-
-```js
-Promise.all([loadTemplates(), owl.utils.whenReady()]).then(function([templates]) {
-  const qweb = new owl.QWeb(templates);
-  const app = new App({ qweb });
-  app.mount(document.body);
-});
-```
-
-```js
-owl.utils.whenReady(function() {
-  const qweb = new owl.QWeb();
-  const app = new App({ qweb });
-  app.mount(document.body);
-});
-```
-
-## `loadJS`
-
-`loadJS` takes a url (string) for a javascript resource, and loads it. It returns
-a promise, so the caller can properly react when it is ready. Also, it is smart:
-it maintains a list of urls previously loaded (or currently being loaded), and
-prevent doing twice the work.
-
-```js
-class MyComponent extends owl.Component {
-  willStart() {
-    return owl.utils.loadJS("/static/libs/someLib.js");
-  }
-}
-```
-
-## `loadTemplates`
-
-```js
-async function makeEnv() {
-  const templates = await owl.utils.loadTemplates("templates.xml");
-  const qweb = new owl.QWeb(templates);
-  return { qweb };
-}
-```
-
-## `escape`
-
-## `debounce`

package.json

@@ -1,8 +1,11 @@
 {
   "name": "owl-framework",
-  "version": "0.23.0",
+  "version": "0.24.1",
   "description": "Odoo Web Library (OWL)",
   "main": "src/index.ts",
+  "engines": {
+    "node": ">=10.15.3"
+  },
   "scripts": {
     "build:js": "tsc --target esnext --module es6 --outDir dist/owl",
     "build:bundle": "rollup -c",
@@ -14,7 +17,8 @@
     "tools:serve": "python3 tools/server.py || python tools/server.py",
     "tools": "npm run build && npm run tools:serve",
     "pretools:watch": "npm run build",
-    "tools:watch": "npm-run-all  --parallel tools:serve \"build:* -- --watch\""
+    "tools:watch": "npm-run-all  --parallel tools:serve \"build:* -- --watch\"",
+    "prettier": "prettier {src/**/*.ts,tests/**/*.ts,doc/**/*.md} --write"
   },
   "repository": {
     "type": "git",
@@ -40,7 +44,7 @@
     "sass": "^1.16.1",
     "source-map-support": "^0.5.10",
     "ts-jest": "^23.10.5",
-    "typescript": "^3.2.2",
+    "typescript": "^3.6.4",
     "uglify-es": "^3.3.9"
   },
   "jest": {

roadmap.md

@@ -0,0 +1,46 @@
+# 🦉 OWL Roadmap 🦉
+
+- Current version: 0.24.1
+- Status: mostly stable
+
+This roadmap is only an attempt at predicting Owl's future.  Everything may
+change!
+
+### October 2019
+
+We plan to complete the following tasks:
+
+- improve API for root widgets (issue #306),
+- replace `t-keepalive`, and maybe `t-transition` by components (issue #295).
+
+### November 2019
+
+Once the previous tasks are done, release version 1.0alpha. This means that the
+API should be stable.  But it could change a little bit if we need it for our
+work on Odoo.
+
+### End of 2019
+
+Release v1.0
+
+- API should be stable,
+- we will use semantic versioning,
+- we will maintain a changelog and an upgrade guide.
+
+### 1.x
+
+- add chrome and firefox devtools,
+- add support for single file components,
+- fix every bugs,
+- improve documentation,
+- small backward compatible improvements.
+
+### 2.x (2021? 2022?)
+
+Maybe:
+
+- reimplement vdom to use *block* system, like Vue 3,
+- refactor `QWeb` to use an intermediate representation (some kind of AST) to
+  allow additional optimisations.
+
+

src/component/component.ts

@@ -2,7 +2,9 @@ import { Observer } from "../core/observer";
 import { CompiledTemplate, QWeb } from "../qweb/index";
 import { h, patch, VNode } from "../vdom/index";
 import "./directive";
+import { Fiber } from "./fiber";
 import "./props_validation";
+import { Scheduler } from "./scheduler";
 
 /**
  * Owl Component System
@@ -11,7 +13,6 @@ import "./props_validation";
  * contains:
  *
  * - the Env interface (generic type for the environment)
- * - the Fiber interface (owl metadata attached to a rendering)
  * - the Internal interface (the owl specific metadata attached to a component)
  * - the Component class
  */
@@ -19,6 +20,8 @@ import "./props_validation";
 //------------------------------------------------------------------------------
 // Types/helpers
 //------------------------------------------------------------------------------
+const raf = window.requestAnimationFrame.bind(window);
+export const scheduler = new Scheduler(raf);
 
 /**
  * An Env (environment) is an object that will be (mostly) shared between all
@@ -34,27 +37,6 @@ export interface Env {
   [key: string]: any;
 }
 
-/**
- * Fibers are small abstractions designed to contain all the internal state
- * associated to a "rendering work unit", relative to a specific component.
- *
- * A rendering will cause the creation of a fiber for each impacted components.
- */
-export interface Fiber<Props> {
-  force: boolean;
-  rootFiber: Fiber<any> | null;
-  isCancelled: boolean;
-  scope: any;
-  vars: any;
-  patchQueue: Fiber<any>[];
-  component: Component<any, any>;
-  vnode: VNode | null;
-  props: Props;
-  promise: Promise<VNode> | null;
-  //   handlers?: any;
-  //   mountedHandlers?: any;
-}
-
 /**
  * This is mostly an internal detail of implementation. The Meta interface is
  * useful to typecheck and describe the internal keys used by Owl to manage the
@@ -65,6 +47,7 @@ interface Internal<T extends Env, Props> {
   // relationships
   readonly id: number;
   vnode: VNode | null;
+  pvnode: VNode | null;
   isMounted: boolean;
   isDestroyed: boolean;
 
@@ -77,11 +60,11 @@ interface Internal<T extends Env, Props> {
   // the component instance back whenever the template is rerendered.
   cmap: { [key: number]: number };
 
-  currentFiber: Fiber<Props> | null;
+  currentFiber: Fiber | null;
 
   boundHandlers: { [key: number]: any };
   observer: Observer | null;
-  render: CompiledTemplate;
+  renderFn: CompiledTemplate;
   mountedCB: Function | null;
   willUnmountCB: Function | null;
   willPatchCB: Function | null;
@@ -151,6 +134,9 @@ export class Component<T extends Env, Props extends {}> {
     //   Con: this is not really safe
     //   Pro: but creating component (by a template) is always unsafe anyway
     this.props = <Props>props || <Props>{};
+    if (QWeb.dev) {
+      QWeb.utils.validateProps(this.constructor, this.props);
+    }
     let id: number = nextId++;
     let p: Component<T, any> | null = null;
     if (parent instanceof Component) {
@@ -159,11 +145,6 @@ export class Component<T extends Env, Props extends {}> {
       parent.__owl__.children[id] = this;
     } else {
       this.env = parent;
-      if (QWeb.dev) {
-        // we only validate props for root widgets here.  "Regular" widget
-        // props are validated by the t-component directive
-        QWeb.utils.validateProps(this.constructor, this.props);
-      }
       this.env.qweb.on("update", this, () => {
         if (this.__owl__.isMounted) {
           this.render(true);
@@ -183,6 +164,7 @@ export class Component<T extends Env, Props extends {}> {
     this.__owl__ = {
       id: id,
       vnode: null,
+      pvnode: null,
       isMounted: false,
       isDestroyed: false,
       parent: p,
@@ -197,7 +179,7 @@ export class Component<T extends Env, Props extends {}> {
       willStartCB: null,
       willUpdatePropsCB: null,
       observer: null,
-      render: qweb.render.bind(qweb, this.__getTemplate(qweb)),
+      renderFn: qweb.render.bind(qweb, this.__getTemplate(qweb)),
       classObj: null,
       refs: null
     };
@@ -278,8 +260,11 @@ export class Component<T extends Env, Props extends {}> {
   /**
    * catchError is a method called whenever some error happens in the rendering or
    * lifecycle hooks of a child.
+   *
+   * It needs to be implemented by a component that is designed to handle the
+   * error properly.
    */
-  catchError(error: Error): void {}
+  catchError?(error?: Error): void;
 
   //--------------------------------------------------------------------------
   // Public
@@ -296,28 +281,37 @@ export class Component<T extends Env, Props extends {}> {
   async mount(target: HTMLElement, renderBeforeRemount: boolean = false): Promise<void> {
     const __owl__ = this.__owl__;
     if (__owl__.isMounted) {
+      return Promise.resolve();
+    }
+    if (__owl__.vnode && !renderBeforeRemount) {
+      target.appendChild(this.el!);
+      if (document.body.contains(target)) {
+        this.__callMounted();
+      }
       return;
     }
-    const fiber = this.__createFiber(false, undefined, undefined, undefined);
+    const fiber = new Fiber(null, this, this.props, undefined, undefined, false);
     if (!__owl__.vnode) {
-      fiber.promise = this.__prepareAndRender(fiber);
-      const vnode = await fiber.promise;
-      if (__owl__.isDestroyed) {
-        // component was destroyed before we get here...
-        return;
-      }
-      this.__patch(vnode);
-    } else if (renderBeforeRemount) {
-      fiber.patchQueue.push(fiber);
-      fiber.promise = this.__render(fiber);
-      await fiber.promise;
-      this.__applyPatchQueue(fiber);
-    }
-    target.appendChild(this.el!);
-
-    if (document.body.contains(target)) {
-      this.__callMounted();
+      this.__prepareAndRender(fiber);
+    } else {
+      this.__render(fiber);
     }
+    return new Promise((resolve, reject) => {
+      scheduler.addFiber(fiber, err => {
+        if (err) {
+          reject(err);
+          return;
+        }
+        if (!__owl__.isDestroyed) {
+          this.__patch(fiber.vnode);
+          target.appendChild(this.el!);
+          if (document.body.contains(target)) {
+            this.__callMounted();
+          }
+        }
+        resolve();
+      });
+    });
   }
 
   /**
@@ -342,19 +336,26 @@ export class Component<T extends Env, Props extends {}> {
    */
   async render(force: boolean = false): Promise<void> {
     const __owl__ = this.__owl__;
-    if (!__owl__.isMounted) {
+    if (
+      (!__owl__.isMounted && !__owl__.currentFiber) ||
+      (__owl__.currentFiber && !__owl__.currentFiber.isRendered)
+    ) {
       return;
     }
-    const fiber = this.__createFiber(force, undefined, undefined, undefined);
-    fiber.patchQueue.push(fiber);
-    fiber.promise = this.__render(fiber);
-    await fiber.promise;
-
-    if (__owl__.isMounted && fiber === __owl__.currentFiber) {
-      // we only update the vnode and the actual DOM if no other rendering
-      // occurred between now and when the render method was initially called.
-      this.__applyPatchQueue(fiber);
-    }
+    const fiber = new Fiber(null, this, this.props, undefined, undefined, force);
+    this.__render(fiber);
+    return new Promise((resolve, reject) => {
+      scheduler.addFiber(fiber.root, err => {
+        if (err) {
+          reject(err);
+          return;
+        }
+        if (__owl__.isMounted && fiber === fiber.root) {
+          fiber.patchComponents();
+        }
+        resolve();
+      });
+    });
   }
 
   /**
@@ -407,27 +408,6 @@ export class Component<T extends Env, Props extends {}> {
   // Private
   //--------------------------------------------------------------------------
 
-  /**
-   * This method is a helper to create a fiber element.
-   */
-  __createFiber(force, scope, vars, parent?: Fiber<any>): Fiber<Props> {
-    const fiber: Fiber<Props> = {
-      force,
-      scope,
-      vars,
-      rootFiber: null,
-      isCancelled: false,
-      component: this,
-      vnode: null,
-      patchQueue: parent ? parent.patchQueue : [],
-      props: this.props,
-      promise: null
-    };
-    fiber.rootFiber = parent ? parent.rootFiber : fiber;
-    this.__owl__.currentFiber = fiber;
-    return fiber;
-  }
-
   /**
    * Private helper to perform a full destroy, from the point of view of an Owl
    * component. It does not remove the el (this is done only once on the top
@@ -478,7 +458,7 @@ export class Component<T extends Env, Props extends {}> {
         __owl__.mountedCB();
       }
     } catch (e) {
-      errorHandler(e, this);
+      console.error(e); // TODO : add a test
     }
   }
 
@@ -504,25 +484,38 @@ export class Component<T extends Env, Props extends {}> {
    */
   async __updateProps(
     nextProps: Props,
-    parentFiber: Fiber<any>,
-    scope?: any,
-    vars?: any
+    parentFiber: Fiber,
+    scope: any,
+    vars: any,
+    previousSibling?: Fiber | null
   ): Promise<void> {
     const shouldUpdate = parentFiber.force || this.shouldUpdate(nextProps);
     if (shouldUpdate) {
+      const __owl__ = this.__owl__;
+      const fiber = new Fiber(parentFiber, this, this.props, scope, vars, parentFiber.force);
+      if (!parentFiber.child) {
+        parentFiber.child = fiber;
+      } else {
+        previousSibling!.sibling = fiber;
+      }
+
       const defaultProps = (<any>this.constructor).defaultProps;
       if (defaultProps) {
         nextProps = this.__applyDefaultProps(nextProps, defaultProps);
       }
+      if (QWeb.dev) {
+        QWeb.utils.validateProps(this.constructor, nextProps);
+      }
       await Promise.all([
         this.willUpdateProps(nextProps),
-        this.__owl__.willUpdatePropsCB && this.__owl__.willUpdatePropsCB(nextProps)
+        __owl__.willUpdatePropsCB && __owl__.willUpdatePropsCB(nextProps)
       ]);
+      if (fiber.isCancelled) {
+        return;
+      }
       this.props = nextProps;
-      const fiber = this.__createFiber(parentFiber.force, scope, vars, parentFiber);
-      fiber.patchQueue.push(fiber);
 
-      await this.__render(fiber);
+      this.__render(fiber);
     }
   }
 
@@ -534,6 +527,7 @@ export class Component<T extends Env, Props extends {}> {
     const __owl__ = this.__owl__;
     const target = __owl__.vnode || document.createElement(vnode.sel!);
     __owl__.vnode = patch(target, vnode);
+    __owl__.currentFiber = null;
   }
 
   /**
@@ -541,10 +535,15 @@ export class Component<T extends Env, Props extends {}> {
    * subcomponent is created. It gets its scope and vars, if any, from the
    * parent template.
    */
-  __prepare(parentFiber: Fiber<any>, scope: any, vars: any): Promise<VNode> {
-    const fiber = this.__createFiber(parentFiber.force, scope, vars, parentFiber);
-    fiber.promise = this.__prepareAndRender(fiber);
-    return fiber.promise;
+  __prepare(parentFiber: Fiber, scope: any, vars: any, previousSibling?: Fiber | null) {
+    const fiber = new Fiber(parentFiber, this, this.props, scope, vars, parentFiber.force);
+    fiber.shouldPatch = false;
+    if (!parentFiber.child) {
+      parentFiber.child = fiber;
+    } else {
+      previousSibling!.sibling = fiber;
+    }
+    return this.__prepareAndRender(fiber);
   }
 
   __getTemplate(qweb: QWeb): string {
@@ -570,68 +569,66 @@ export class Component<T extends Env, Props extends {}> {
     }
     return p._template;
   }
-  async __prepareAndRender(fiber: Fiber<Props>): Promise<VNode> {
+  async __prepareAndRender(fiber: Fiber) {
     try {
       await Promise.all([this.willStart(), this.__owl__.willStartCB && this.__owl__.willStartCB()]);
     } catch (e) {
-      errorHandler(e, this);
-      return Promise.resolve(h("div"));
+      fiber.handleError(e);
+      fiber.vnode = h("div"); // -> we render this div at the end
+      return Promise.resolve();
     }
-    const __owl__ = this.__owl__;
-    if (__owl__.isDestroyed) {
-      return Promise.resolve(h("div"));
+    if (this.__owl__.isDestroyed) {
+      return Promise.resolve();
+    }
+    if (!fiber.isCancelled) {
+      this.__render(fiber);
     }
-    return this.__render(fiber);
   }
 
-  __render(fiber: Fiber<Props>): Promise<VNode> {
+  __render(fiber: Fiber) {
     const __owl__ = this.__owl__;
-    const promises: Promise<void>[] = [];
     if (__owl__.observer) {
       __owl__.observer.allowMutations = false;
     }
     let vnode;
     try {
-      vnode = __owl__.render!(this, {
-        promises,
+      vnode = __owl__.renderFn!(this, {
         handlers: __owl__.boundHandlers,
         fiber: fiber
       });
     } catch (e) {
       vnode = __owl__.vnode || h("div");
-      errorHandler(e, this);
+      fiber.handleError(e);
     }
     fiber.vnode = vnode;
     if (__owl__.observer) {
       __owl__.observer.allowMutations = true;
     }
 
-    // this part is critical for the patching process to be done correctly. The
-    // tricky part is that a child component can be rerendered on its own, which
-    // will update its own vnode representation without the knowledge of the
-    // parent component.  With this, we make sure that the parent component will be
-    // able to patch itself properly after
-    vnode.key = __owl__.id;
-
-    // we applly here the class information described on the component by the
+    // we apply here the class information described on the component by the
     // template (so, something like <MyComponent class="..."/>) to the actual
     // root vnode
     if (__owl__.classObj) {
       vnode.data.class = Object.assign(vnode.data.class || {}, __owl__.classObj);
     }
-
-    return Promise.all(promises).then(() => vnode);
+    fiber.root.counter--;
+    fiber.isRendered = true;
   }
 
   /**
    * Only called by qweb t-component directive
    */
-  __mount(vnode: VNode, elm: HTMLElement): VNode {
+  __mount(fiber: Fiber, elm: HTMLElement): VNode {
+    if (fiber !== this.__owl__.currentFiber) {
+      fiber = this.__owl__.currentFiber!; // TODO: check if we can remove fiber arg
+    }
+    const vnode = fiber.vnode!;
     const __owl__ = this.__owl__;
     if (__owl__.classObj) {
       (<any>vnode).data.class = Object.assign((<any>vnode).data.class || {}, __owl__.classObj);
     }
     __owl__.vnode = patch(elm, vnode);
+    __owl__.currentFiber = null;
     if (__owl__.parent!.__owl__.isMounted && !__owl__.isMounted) {
       this.__callMounted();
     }
@@ -664,72 +661,4 @@ export class Component<T extends Env, Props extends {}> {
     }
     return <Props>props;
   }
-
-  /**
-   * Apply the given patch queue from a fiber.
-   *   1) Call 'willPatch' on the component of each patch
-   *   2) Call '__patch' on the component of each patch
-   *   3) Call 'patched' on the component of each patch, in reverse order
-   */
-  __applyPatchQueue(fiber: Fiber<Props>) {
-    const patchQueue = fiber.patchQueue;
-    let component: Component<any, any> = this;
-    try {
-      const patchLen = patchQueue.length;
-      for (let i = 0; i < patchLen; i++) {
-        component = patchQueue[i].component;
-        if (component.__owl__.willPatchCB) {
-          component.__owl__.willPatchCB();
-        }
-        component.willPatch();
-      }
-      for (let i = 0; i < patchLen; i++) {
-        const fiber = patchQueue[i];
-        component = fiber.component;
-        component.__patch(fiber.vnode);
-      }
-      for (let i = patchLen - 1; i >= 0; i--) {
-        component = patchQueue[i].component;
-        component.patched();
-        if (component.__owl__.patchedCB) {
-          component.__owl__.patchedCB();
-        }
-      }
-    } catch (e) {
-      errorHandler(e, component);
-    }
-  }
-}
-
-//------------------------------------------------------------------------------
-// Error handling
-//------------------------------------------------------------------------------
-
-/**
- * This is the global error handler for errors occurring in Owl main lifecycle
- * methods.  Caught errors are triggered on the QWeb instance, and are
- * potentially given to some parent component which implements `catchError`.
- *
- * If there are no such component, we destroy everything. This is better than
- * being in a corrupted state.
- */
-function errorHandler(error: Error, component: Component<any, any>) {
-  let canCatch = false;
-  let qweb = component.env.qweb;
-  let root = component;
-  while (component && !(canCatch = component.catchError !== Component.prototype.catchError)) {
-    root = component;
-    component = component.__owl__.parent!;
-  }
-  console.error(error);
-  // we trigger error on QWeb so it can be logged/handled
-  qweb.trigger("error", error);
-
-  if (canCatch) {
-    setTimeout(() => {
-      component.catchError(error);
-    });
-  } else {
-    root.destroy();
-  }
 }

src/component/directive.ts

@@ -186,7 +186,7 @@ QWeb.utils.defineProxy = function defineProxy(target, source) {
 
 QWeb.addDirective({
   name: "component",
-  extraNames: ["props", "keepalive", "asyncroot"],
+  extraNames: ["props", "keepalive"],
   priority: 100,
   atNodeEncounter({ ctx, value, node, qweb }): boolean {
     ctx.addLine("//COMPONENT");
@@ -196,7 +196,6 @@ QWeb.addDirective({
     ctx.rootContext.shouldDefineUtils = true;
     let keepAlive = node.getAttribute("t-keepalive") ? true : false;
     let hasDynamicProps = node.getAttribute("t-props") ? true : false;
-    let async = node.getAttribute("t-asyncroot") ? true : false;
 
     // t-on- events and t-transition
     const events: [string, string[], string, string][] = [];
@@ -209,11 +208,11 @@ QWeb.addDirective({
       if (name.startsWith("t-on-")) {
         const [eventName, ...mods] = name.slice(5).split(".");
         let extraArgs;
-        let handlerName = value.replace(/\(.*\)/, function(args) {
+        let handlerValue = value.replace(/\(.*\)/, function(args) {
           extraArgs = args.slice(1, -1);
           return "";
         });
-        events.push([eventName, mods, handlerName, extraArgs]);
+        events.push([eventName, mods, handlerValue, extraArgs]);
       } else if (name === "t-transition") {
         transition = value;
       } else if (!name.startsWith("t-")) {
@@ -224,40 +223,25 @@ QWeb.addDirective({
       }
     }
 
-    let key = node.getAttribute("t-key");
-    if (key) {
-      key = ctx.formatExpression(key);
-    }
-
     // computing the props string representing the props object
     let propStr = Object.keys(props)
       .map(k => k + ":" + props[k])
       .join(",");
-    let dummyID = ctx.generateID();
     let defID = ctx.generateID();
     let componentID = ctx.generateID();
-    let keyID = key && ctx.generateID();
-    if (key) {
-      // we bind a variable to the key (could be a complex expression, so we
-      // want to evaluate it only once)
-      ctx.addLine(`let key${keyID} = 'key' + ${key};`);
+
+    let locationExpr = `\`__${ctx.generateID()}__`;
+    for (let i = 0; i < ctx.loopNumber - 1; i++) {
+      locationExpr += `\${i${i + 1}}__`;
     }
-    ctx.addLine(`let def${defID};`);
-    let templateID = key
-      ? `key${keyID}`
-      : ctx.inLoop
-      ? ctx.currentKey
-        ? `String(${ctx.currentKey} + '_k_' + i + '_c_' + ${componentID} )`
-        : `String(-${componentID} - i)`
-      : String(componentID);
-    if (ctx.allowMultipleRoots) {
-      templateID = `"_slot_${templateID}"`;
-    }
-    if (key || ctx.inLoop) {
-      let id = ctx.generateID();
-      ctx.addLine(`let templateId${id} = ${templateID};`);
-      templateID = `templateId${id}`;
+    if (ctx.lastNodeKey || ctx.currentKey) {
+      const k = ctx.lastNodeKey || ctx.currentKey;
+      ctx.addLine(`let templateId${componentID} = ${locationExpr}\` + ${k};`);
+    } else {
+      locationExpr += ctx.loopNumber ? `\${i${ctx.loopNumber}}__\`` : "`";
+      ctx.addLine(`let templateId${componentID} = ${locationExpr};`);
     }
+    const templateId = `templateId${componentID}`;
 
     let ref = node.getAttribute("t-ref");
     let refExpr = "";
@@ -317,10 +301,10 @@ QWeb.addDirective({
         }
       }
       let eventsCode = events
-        .map(function([eventName, mods, handlerName, extraArgs]) {
+        .map(function([eventName, mods, handlerValue, extraArgs]) {
           let params = "owner";
           if (extraArgs) {
-            if (ctx.inLoop) {
+            if (ctx.loopNumber) {
               let argId = ctx.generateID();
               // we need to evaluate the arguments now, because the handler will
               // be set asynchronously later when the widget is ready, and the
@@ -331,18 +315,17 @@ QWeb.addDirective({
               params = `owner, ${ctx.formatExpression(extraArgs)}`;
             }
           }
-          let handler;
-          if (mods.length > 0) {
-            handler = `function (e) {`;
-            handler += mods
-              .map(function(mod) {
-                return T_COMPONENT_MODS_CODE[mod];
-              })
-              .join("");
-            handler += `owner['${handlerName}'].call(${params}, e);}`;
-          } else {
-            handler = `owner['${handlerName}'].bind(${params})`;
+          let handler = `function (e) {`;
+          handler += mods
+            .map(function(mod) {
+              return T_COMPONENT_MODS_CODE[mod];
+            })
+            .join("");
+          if (handlerValue) {
+            handler += `const fn = owner['${handlerValue}'];`;
+            handler += `if (fn) { fn.call(${params}, e); } else { owner.${handlerValue}; }`;
           }
+          handler += `}`;
           return `vn.elm.addEventListener('${eventName}', ${handler});`;
         })
         .join("");
@@ -352,32 +335,21 @@ QWeb.addDirective({
     }
 
     ctx.addLine(
-      `let w${componentID} = ${templateID} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateID}]] : false;`
+      `let w${componentID} = ${templateId} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateId}]] : false;`
     );
-    if (ctx.parentNode) {
-      ctx.addLine(`let _${dummyID}_index = c${ctx.parentNode}.length;`);
-    }
-    let shouldProxy = false;
-    if (async || keepAlive) {
+    let shouldProxy = !ctx.parentNode;
+    if (keepAlive) {
       ctx.addLine(
         `const fiber${componentID} = Object.assign(Object.create(extra.fiber), {patchQueue: []});`
       );
     }
-    if (async) {
-      ctx.addLine(
-        `c${ctx.parentNode}.push(w${componentID} && w${componentID}.__owl__.pvnode || null);`
-      );
-    } else {
-      if (ctx.parentNode) {
-        ctx.addLine(`c${ctx.parentNode}.push(null);`);
-      } else {
-        let id = ctx.generateID();
-        ctx.rootContext.rootNode = id;
-        shouldProxy = true;
-        ctx.rootContext.shouldDefineResult = true;
-        ctx.addLine(`let vn${id} = {};`);
-        ctx.addLine(`result = vn${id};`);
-      }
+    if (shouldProxy) {
+      let id = ctx.generateID();
+      ctx.rootContext.rootNode = id;
+      shouldProxy = true;
+      ctx.rootContext.shouldDefineResult = true;
+      ctx.addLine(`let vn${id} = {};`);
+      ctx.addLine(`result = vn${id};`);
     }
     if (hasDynamicProps) {
       const dynamicProp = ctx.formatExpression(node.getAttribute("t-props")!);
@@ -388,17 +360,70 @@ QWeb.addDirective({
     ctx.addIf(
       `w${componentID} && w${componentID}.__owl__.currentFiber && !w${componentID}.__owl__.vnode`
     );
-    ctx.addIf(
-      `utils.shallowEqual(props${componentID}, w${componentID}.__owl__.currentFiber.props)`
-    );
-    ctx.addLine(`def${defID} = w${componentID}.__owl__.currentFiber.promise;`);
-    ctx.addElse();
     ctx.addLine(`w${componentID}.destroy();`);
     ctx.addLine(`w${componentID} = false;`);
     ctx.closeIf();
-    ctx.closeIf();
 
-    ctx.addIf(`!w${componentID}`);
+    let registerCode = "";
+    if (shouldProxy) {
+      registerCode = `utils.defineProxy(vn${ctx.rootNode}, pvnode);`;
+    }
+
+    // SLOTS
+    const varDefs: string[] = [];
+    const hasSlots = node.childNodes.length;
+    if (hasSlots) {
+      ctx.rootContext.shouldTrackScope = true;
+      for (let v of Object.values(ctx.variables)) {
+        if (v["id"]) {
+          varDefs.push(v["id"]);
+        }
+      }
+    }
+
+    let scopeVars;
+    if (hasSlots) {
+      let scope = ctx.scopeVars.length ? `Object.assign({}, scope)` : `{}`;
+      let vars = varDefs.length ? `{${varDefs.join(",")}}` : "undefined";
+      scopeVars = `${scope}, ${vars}`;
+    } else {
+      scopeVars = "undefined, undefined";
+    }
+
+    ctx.addIf(`w${componentID}`);
+
+    // need to update component
+    let patchQueueCode = keepAlive ? `fiber${componentID}` : "extra.fiber";
+    if (keepAlive) {
+      // if we have t-keepalive="1", the component could be unmounted, but then
+      // we __updateProps is called.  This is ok, but we do not want to call
+      // the willPatch/patched hooks of the component in this case, so we
+      // disable the patch queue
+      patchQueueCode = `w${componentID}.__owl__.isMounted ? extra.fiber : fiber${componentID}`;
+    }
+    let styleCode = "";
+    if (tattStyle) {
+      styleCode = `.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};w${componentID}.el.style=${tattStyle};});`;
+    }
+    ctx.addLine(
+      `w${componentID}.__updateProps(props${componentID}, ${patchQueueCode}${scopeVars &&
+        ", " + scopeVars}, sibling)${styleCode};`
+    );
+    ctx.addLine(`let pvnode = w${componentID}.__owl__.pvnode;`);
+    let keepAliveCode = "";
+    if (keepAlive) {
+      keepAliveCode = `pvnode.data.hook.insert = vn => {vn.elm.parentNode.replaceChild(w${componentID}.el,vn.elm);vn.elm=w${componentID}.el;w${componentID}.__remount();};`;
+      ctx.addLine(keepAliveCode);
+    }
+    if (registerCode) {
+      ctx.addLine(registerCode);
+    }
+    if (ctx.parentNode) {
+      ctx.addLine(`c${ctx.parentNode}.push(pvnode);`);
+    }
+
+    ctx.addElse();
+
     // new component
     let dynamicFallback = "";
     if (!value.match(INTERP_REGEXP)) {
@@ -414,23 +439,10 @@ QWeb.addDirective({
     ctx.addLine(
       `if (!W${componentID}) {throw new Error('Cannot find the definition of component "' + componentKey${componentID} + '"')}`
     );
-    if (QWeb.dev) {
-      ctx.addLine(`utils.validateProps(W${componentID}, props${componentID})`);
-    }
     ctx.addLine(`w${componentID} = new W${componentID}(parent, props${componentID});`);
-    ctx.addLine(`parent.__owl__.cmap[${templateID}] = w${componentID}.__owl__.id;`);
+    ctx.addLine(`parent.__owl__.cmap[${templateId}] = w${componentID}.__owl__.id;`);
 
-    // SLOTS
-    const varDefs: string[] = [];
-    const hasSlots = node.childNodes.length;
     if (hasSlots) {
-      ctx.rootContext.shouldTrackScope = true;
-      for (let v of Object.values(ctx.variables)) {
-        if (v["id"]) {
-          varDefs.push(v["id"]);
-        }
-      }
-
       const clone = <Element>node.cloneNode(true);
       const slotNodes = clone.querySelectorAll("[t-set]");
       const slotId = QWeb.nextSlotId++;
@@ -455,67 +467,30 @@ QWeb.addDirective({
       }
     }
 
-    let scopeVars;
-    if (hasSlots) {
-      let scope = ctx.scopeVars.length ? `Object.assign({}, scope)` : `{}`;
-      let vars = varDefs.length ? `{${varDefs.join(",")}}` : "undefined";
-      scopeVars = `${scope}, ${vars}`;
-    } else {
-      scopeVars = "undefined, undefined";
-    }
-    ctx.addLine(`def${defID} = w${componentID}.__prepare(extra.fiber, ${scopeVars});`);
+    ctx.addLine(`let def${defID} = w${componentID}.__prepare(extra.fiber, ${scopeVars}, sibling);`);
     // hack: specify empty remove hook to prevent the node from being removed from the DOM
-    let registerCode = `c${ctx.parentNode}[_${dummyID}_index]=pvnode;`;
-    if (shouldProxy) {
-      registerCode = `utils.defineProxy(vn${ctx.rootNode}, pvnode);`;
-    }
     ctx.addLine(
-      `def${defID} = def${defID}.then(vnode=>{if (w${componentID}.__owl__.isDestroyed){return}${createHook}let pvnode=h(vnode.sel, {key: ${templateID}, hook: {insert(vn) {let nvn=w${componentID}.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}${transitionsInsertCode}},remove() {},destroy(vn) {${finalizeComponentCode}}}});${registerCode}w${componentID}.__owl__.pvnode = pvnode;});`
+      `let pvnode = h('dummy', {key: ${templateId}, hook: {insert(vn) { let nvn=w${componentID}.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}${transitionsInsertCode}},remove() {},destroy(vn) {${finalizeComponentCode}}}});`
     );
+    ctx.addLine(`const fiber = w${componentID}.__owl__.currentFiber;`);
+    ctx.addLine(
+      `def${defID}.then(function () {if (w${componentID}.__owl__.isDestroyed) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
+    );
+    if (registerCode) {
+      ctx.addLine(registerCode);
+    }
+    if (ctx.parentNode) {
+      ctx.addLine(`c${ctx.parentNode}.push(pvnode);`);
+    }
+    ctx.addLine(`w${componentID}.__owl__.pvnode = pvnode;`);
 
-    ctx.addElse();
-    // need to update component
-    let patchQueueCode = async || keepAlive ? `fiber${componentID}` : "extra.fiber";
-    if (keepAlive) {
-      // if we have t-keepalive="1", the component could be unmounted, but then
-      // we __updateProps is called.  This is ok, but we do not want to call
-      // the willPatch/patched hooks of the component in this case, so we
-      // disable the patch queue
-      patchQueueCode = `w${componentID}.__owl__.isMounted ? extra.fiber : fiber${componentID}`;
-    }
-    if (QWeb.dev) {
-      ctx.addLine(`utils.validateProps(w${componentID}.constructor, props${componentID})`);
-    }
-    ctx.addLine(
-      `def${defID} = def${defID} || w${componentID}.__updateProps(props${componentID}, ${patchQueueCode}${scopeVars &&
-        ", " + scopeVars});`
-    );
-    let keepAliveCode = "";
-    if (keepAlive) {
-      keepAliveCode = `pvnode.data.hook.insert = vn => {vn.elm.parentNode.replaceChild(w${componentID}.el,vn.elm);vn.elm=w${componentID}.el;w${componentID}.__remount();};`;
-    }
-    ctx.addLine(
-      `def${defID} = def${defID}.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};${
-        tattStyle ? `w${componentID}.el.style=${tattStyle};` : ""
-      }let pvnode=w${componentID}.__owl__.pvnode;${keepAliveCode}${registerCode}});`
-    );
     ctx.closeIf();
 
     if (classObj) {
       ctx.addLine(`w${componentID}.__owl__.classObj=${classObj};`);
     }
 
-    if (async) {
-      ctx.addLine(
-        `def${defID}.then(w${componentID}.__applyPatchQueue.bind(w${componentID}, fiber${componentID}));`
-      );
-    } else {
-      ctx.addLine(`extra.promises.push(def${defID});`);
-    }
-
-    if (node.hasAttribute("t-if") || node.hasAttribute("t-else") || node.hasAttribute("t-elif")) {
-      ctx.closeIf();
-    }
+    ctx.addLine(`sibling = w${componentID}.__owl__.currentFiber || sibling;`);
 
     return true;
   }

src/component/fiber.ts

@@ -0,0 +1,223 @@
+import { VNode } from "../vdom/index";
+import { Component } from "./component";
+
+/**
+ * Owl Fiber Class
+ *
+ * Fibers are small abstractions designed to contain all the internal state
+ * associated with a "rendering work unit", relative to a specific component.
+ *
+ * A rendering will cause the creation of a fiber for each impacted components.
+ *
+ * Fibers capture all that necessary information, which is critical to owl
+ * asynchronous rendering pipeline. Fibers can be cancelled, can be in different
+ * states and in general determine the state of the rendering.
+ */
+
+export class Fiber {
+  // The force attribute determines if a rendering should bypass the `shouldUpdate`
+  // method potentially implemented by a component. It is usually set to false.
+  force: boolean;
+
+  // isCancelled means that the rendering corresponding to this fiber and its
+  // children is cancelled. No extra work should be done.
+  isCancelled: boolean = false;
+
+  // the fibers corresponding to component updates (updateProps) need to call
+  // the willPatch and patched hooks from the corresponding component. However,
+  // fibers corresponding to a new component do not need to do that. So, the
+  // shouldPatch hook is the boolean that we check whenever we need to apply
+  // a patch.
+  shouldPatch: boolean = true;
+
+  // isRendered is the last state of a fiber. If true, this means that it has
+  // been rendered and is inert (so, it should not be taken into account when
+  // counting the number of active fibers).
+  isRendered: boolean = false;
+
+  // the counter number is a critical information. It is only necessary for a
+  // root fiber.  For that fiber, this number counts the number of active sub
+  // fibers.  When that number reaches 0, the fiber can be applied by the
+  // scheduler.
+  counter: number = 0;
+
+  scope: any;
+  vars: any;
+  props: any;
+
+  component: Component<any, any>;
+  vnode: VNode | null = null;
+
+  root: Fiber;
+  child: Fiber | null = null;
+  sibling: Fiber | null = null;
+  parent: Fiber | null = null;
+
+  error?: Error;
+
+  constructor(parent: Fiber | null, component: Component<any, any>, props, scope, vars, force) {
+    this.force = force;
+    this.scope = scope;
+    this.vars = vars;
+    this.props = props;
+    this.component = component;
+
+    this.root = parent ? parent.root : this;
+    this.parent = parent;
+
+    let oldFiber = component.__owl__.currentFiber;
+    if (oldFiber && !oldFiber.isCancelled) {
+      this._remapFiber(oldFiber);
+    }
+
+    this.root.counter++;
+
+    component.__owl__.currentFiber = this;
+  }
+
+  /**
+   * In some cases, a rendering initiated at some component can detect that it
+   * should be part of a larger rendering initiated somewhere up the component
+   * tree.  In that case, it needs to cancel the previous rendering and
+   * remap itself as a part of the current parent rendering.
+   */
+  _remapFiber(oldFiber: Fiber) {
+    oldFiber.cancel();
+    if (oldFiber === oldFiber.root) {
+      oldFiber.root.counter++;
+    }
+    if (oldFiber.parent && !this.parent) {
+      // re-map links
+      this.parent = oldFiber.parent;
+      this.root = this.parent.root;
+      this.sibling = oldFiber.sibling;
+      if (this.parent.child === oldFiber) {
+        this.parent.child = this;
+      } else {
+        let current = this.parent.child!;
+        while (true) {
+          if (current.sibling === oldFiber) {
+            current.sibling = this;
+            break;
+          }
+          current = current.sibling!;
+        }
+      }
+    }
+  }
+
+  /**
+   * This function has been taken from
+   * https://medium.com/react-in-depth/the-how-and-why-on-reacts-usage-of-linked-list-in-fiber-67f1014d0eb7
+   */
+  _walk(doWork: (f: Fiber) => Fiber | null) {
+    let root = this;
+    let current: Fiber = this;
+    while (true) {
+      const child = doWork(current);
+      if (child) {
+        current = child;
+        continue;
+      }
+      if (current === root) {
+        return;
+      }
+      while (!current.sibling) {
+        if (!current.parent || current.parent === root) {
+          return;
+        }
+        current = current.parent;
+      }
+      current = current.sibling;
+    }
+  }
+
+  /**
+   * Apply the given patch queue from a fiber.
+   *   1) Call 'willPatch' on the component of each patch
+   *   2) Call '__patch' on the component of each patch
+   *   3) Call 'patched' on the component of each patch, in reverse order
+   */
+  patchComponents() {
+    const patchQueue: Fiber[] = [];
+    const doWork: (Fiber) => Fiber | null = function(f) {
+      if (f.shouldPatch) {
+        patchQueue.push(f);
+      }
+      return f.child;
+    };
+    this._walk(doWork);
+    let component: Component<any, any> = this.component;
+    const patchLen = patchQueue.length;
+    try {
+      for (let i = 0; i < patchLen; i++) {
+        component = patchQueue[i].component;
+        if (component.__owl__.willPatchCB) {
+          component.__owl__.willPatchCB();
+        }
+        component.willPatch();
+      }
+    } catch (e) {
+      console.error(e);
+    }
+    for (let i = 0; i < patchLen; i++) {
+      const fiber = patchQueue[i];
+      component = fiber.component;
+      component.__patch(fiber.vnode);
+    }
+    try {
+      for (let i = patchLen - 1; i >= 0; i--) {
+        component = patchQueue[i].component;
+        component.patched();
+        if (component.__owl__.patchedCB) {
+          component.__owl__.patchedCB();
+        }
+      }
+    } catch (e) {
+      console.error(e);
+    }
+  }
+
+  /**
+   * Cancel a fiber and all its children.
+   */
+  cancel() {
+    this._walk(f => {
+      if (!f.isRendered) {
+        f.root.counter--;
+      }
+      f.isCancelled = true;
+      return f.child;
+    });
+  }
+
+  /**
+   * This is the global error handler for errors occurring in Owl main lifecycle
+   * methods.  Caught errors are triggered on the QWeb instance, and are
+   * potentially given to some parent component which implements `catchError`.
+   *
+   * If there are no such component, we destroy everything. This is better than
+   * being in a corrupted state.
+   */
+  handleError(error: Error) {
+    let canCatch = false;
+    let component = this.component;
+    let qweb = component.env.qweb;
+    let root = component;
+    while (component && !(canCatch = !!component.catchError)) {
+      root = component;
+      component = component.__owl__.parent!;
+    }
+    qweb.trigger("error", error);
+
+    if (canCatch) {
+      setTimeout(() => {
+        console.error(error);
+        component.catchError!(error);
+      });
+    } else {
+      this.root.error = error;
+      root.destroy();
+    }
+  }
+}

src/component/props_validation.ts

@@ -21,7 +21,7 @@ QWeb.utils.validateProps = function(Widget, props: Object) {
         // optional prop
         break;
       }
-      if (!props[propName]) {
+      if (!(propName in props)) {
         throw new Error(`Missing props '${propsDef[i]}' (component '${Widget.name}')`);
       }
     }

src/component/scheduler.ts

@@ -0,0 +1,67 @@
+import { Fiber } from "./fiber";
+
+/**
+ * Owl Scheduler Class
+ *
+ * The scheduler is the part of Owl that will effectively apply a rendering
+ * whenever a fiber is ready.
+ *
+ * Briefly, it can be used to register root fibers.  Whenever there is an
+ * active root fiber, it will poll continuously each animation frame (so, about
+ * once every 16ms) and whenever a root fiber is ready, it will apply it.
+ */
+
+interface Task {
+  fiber: Fiber;
+  callback: (err?: Error) => void;
+}
+
+export class Scheduler {
+  tasks: Task[] = [];
+  isRunning: boolean = false;
+  requestAnimationFrame: typeof window.requestAnimationFrame;
+
+  constructor(requestAnimationFrame) {
+    this.requestAnimationFrame = requestAnimationFrame;
+  }
+
+  addFiber(fiber, callback) {
+    this.tasks.push({ fiber, callback });
+    if (this.isRunning) {
+      return;
+    }
+    this.scheduleTasks();
+  }
+
+  /**
+   * Process all current tasks. This only applies to the fibers that are ready.
+   * Other tasks are left unchanged.
+   */
+  flush() {
+    let tasks = this.tasks;
+    this.tasks = [];
+    tasks = tasks.filter(task => {
+      if (task.fiber.isCancelled) {
+        return false;
+      }
+      if (task.fiber.counter === 0) {
+        task.callback(task.fiber.error);
+        return false;
+      }
+      return true;
+    });
+    this.tasks = tasks.concat(this.tasks);
+  }
+
+  scheduleTasks() {
+    this.isRunning = true;
+    this.requestAnimationFrame(() => {
+      this.flush();
+      if (this.tasks.length > 0) {
+        this.scheduleTasks();
+      } else {
+        this.isRunning = false;
+      }
+    });
+  }
+}

src/context.ts

@@ -1,8 +1,7 @@
-import { Component } from "./component/component";
-import { Observer } from "./core/observer";
+import { Component, scheduler } from "./component/component";
 import { EventBus } from "./core/event_bus";
+import { Observer } from "./core/observer";
 import { onWillUnmount } from "./hooks";
-
 /**
  * The `Context` object provides a way to share data between an arbitrary number
  * of component. Usually, data is passed from a parent to its children component,
@@ -16,7 +15,7 @@ import { onWillUnmount } from "./hooks";
 export class Context extends EventBus {
   state: any;
   observer: Observer;
-  id: number = 1;
+  rev: number = 1;
   // mapping from component id to last observed context id
   mapping: { [componentId: number]: number } = {};
 
@@ -47,13 +46,15 @@ export class Context extends EventBus {
    * with the same depth in parallel.
    */
   async __notifyComponents() {
-    const id = ++this.id;
+    const rev = ++this.rev;
     const subs = this.subscriptions.update || [];
     for (let i = 0, iLen = subs.length; i < iLen; i++) {
       const sub = subs[i];
       const shouldCallback = sub.owner ? sub.owner.__owl__.isMounted : true;
       if (shouldCallback) {
-        await sub.callback.call(sub.owner, id);
+        const render = sub.callback.call(sub.owner, rev);
+        scheduler.flush();
+        await render;
       }
     }
   }
@@ -68,22 +69,37 @@ export function useContext(ctx: Context): any {
   return useContextWithCB(ctx, component, component.render.bind(component));
 }
 
-export function useContextWithCB(ctx: Context, component, method): any {
+export function useContextWithCB(ctx: Context, component: Component<any, any>, method): any {
   const __owl__ = component.__owl__;
   const id = __owl__.id;
   const mapping = ctx.mapping;
   if (id in mapping) {
     return ctx.state;
   }
+  if (!__owl__.observer) {
+    __owl__.observer = new Observer();
+    __owl__.observer.notifyCB = component.render.bind(component);
+  }
+  const currentCB = __owl__.observer.notifyCB;
+  __owl__.observer.notifyCB = function() {
+    if (ctx.rev > mapping[id]) {
+      // in this case, the context has been updated since we were rendering
+      // last, and we do not need to render here with the observer. A
+      // rendering is coming anyway, with the correct props.
+      return;
+    }
+    currentCB();
+  };
+
   mapping[id] = 0;
-  const renderFn = __owl__.render;
-  __owl__.render = function(comp, params) {
-    mapping[id] = ctx.id;
+  const renderFn = __owl__.renderFn;
+  __owl__.renderFn = function(comp, params) {
+    mapping[id] = ctx.rev;
     return renderFn(comp, params);
   };
-  ctx.on("update", component, async contextId => {
-    if (mapping[id] < contextId) {
-      mapping[id] = contextId;
+  ctx.on("update", component, async contextRev => {
+    if (mapping[id] < contextRev) {
+      mapping[id] = contextRev;
       await method();
     }
   });

src/index.ts

@@ -10,6 +10,7 @@ import { QWeb } from "./qweb/index";
 import * as _store from "./store";
 import * as _utils from "./utils";
 import * as _tags from "./tags";
+import { AsyncRoot } from "./misc/async_root";
 import * as _hooks from "./hooks";
 import * as _context from "./context";
 import { Link } from "./router/link";
@@ -26,6 +27,7 @@ export const router = { Router, RouteComponent, Link };
 export const Store = _store.Store;
 export const utils = _utils;
 export const tags = _tags;
+export const misc = { AsyncRoot };
 export const hooks = Object.assign({}, _hooks, {
   useContext: _context.useContext,
   useDispatch: _store.useDispatch,

src/misc/async_root.ts

@@ -0,0 +1,19 @@
+import { Component } from "../component/component";
+import { xml } from "../tags";
+
+/**
+ * AsyncRoot
+ *
+ * Owl is by default asynchronous, and the user interface will wait for all its
+ * subcomponents to be rendered before updating the DOM. This is most of the
+ * time what we want, but in some cases, it makes sense to "detach" a component
+ * from this coordination.  This is the goal of the AsyncRoot component.
+ */
+
+export class AsyncRoot extends Component<any, any> {
+  static template = xml`<t t-slot="default"/>`;
+
+  async __updateProps(nextProps, parentFiber) {
+    this.render(parentFiber.force);
+  }
+}

src/qweb/base_directives.ts

@@ -133,7 +133,7 @@ QWeb.addDirective({
   priority: 20,
   atNodeEncounter({ node, ctx }): boolean {
     let cond = ctx.getValue(node.getAttribute("t-if")!);
-    ctx.addIf(`${ctx.formatExpression(cond)}`);
+    ctx.addIf(typeof cond === "string" ? ctx.formatExpression(cond) : cond.id);
     return false;
   },
   finalize({ ctx }) {
@@ -146,7 +146,7 @@ QWeb.addDirective({
   priority: 30,
   atNodeEncounter({ node, ctx }): boolean {
     let cond = ctx.getValue(node.getAttribute("t-elif")!);
-    ctx.addLine(`else if (${ctx.formatExpression(cond)}) {`);
+    ctx.addLine(`else if (${typeof cond === "string" ? ctx.formatExpression(cond) : cond.id}) {`);
     ctx.indent();
     return false;
   },
@@ -258,10 +258,6 @@ QWeb.addDirective({
       ctx.addLine("}");
     }
 
-    if (node.hasAttribute("t-if") || node.hasAttribute("t-else") || node.hasAttribute("t-elif")) {
-      ctx.closeIf();
-    }
-
     return true;
   }
 });
@@ -275,7 +271,7 @@ QWeb.addDirective({
   priority: 10,
   atNodeEncounter({ node, qweb, ctx }): boolean {
     ctx.rootContext.shouldProtectContext = true;
-    ctx = ctx.subContext("inLoop", true);
+    ctx = ctx.subContext("loopNumber", ctx.loopNumber + 1);
     const elems = node.getAttribute("t-foreach")!;
     const name = node.getAttribute("t-as")!;
     let arrayID = ctx.generateID();
@@ -289,33 +285,26 @@ QWeb.addDirective({
     ctx.addLine(`_${valuesID} = Object.values(_${arrayID});`);
     ctx.closeIf();
     ctx.addLine(`var _length${keysID} = _${keysID}.length;`);
-    ctx.addLine(`for (let i = 0; i < _length${keysID}; i++) {`);
+    const loopVar = `i${ctx.loopNumber}`;
+    ctx.addLine(`for (let ${loopVar} = 0; ${loopVar} < _length${keysID}; ${loopVar}++) {`);
     ctx.indent();
-    ctx.addToScope(name + "_first", "i === 0");
-    ctx.addToScope(name + "_last", `i === _length${keysID} - 1`);
-    ctx.addToScope(name + "_index", "i");
-    ctx.addToScope(name, `_${keysID}[i]`);
-    ctx.addToScope(name + "_value", `_${valuesID}[i]`);
+    ctx.addToScope(name + "_first", `${loopVar} === 0`);
+    ctx.addToScope(name + "_last", `${loopVar} === _length${keysID} - 1`);
+    ctx.addToScope(name + "_index", loopVar);
+    ctx.addToScope(name, `_${keysID}[${loopVar}]`);
+    ctx.addToScope(name + "_value", `_${valuesID}[${loopVar}]`);
     const nodeCopy = <Element>node.cloneNode(true);
-    let shouldWarn = nodeCopy.tagName !== "t" && !nodeCopy.hasAttribute("t-key");
-    if (!shouldWarn && node.tagName === "t") {
-      if (node.hasAttribute("t-component") && !node.hasAttribute("t-key")) {
-        shouldWarn = true;
-      }
-      if (
-        !shouldWarn &&
-        node.children.length === 1 &&
-        node.children[0].tagName !== "t" &&
-        !node.children[0].hasAttribute("t-key")
-      ) {
-        shouldWarn = true;
-      }
-    }
+    let shouldWarn =
+      !nodeCopy.hasAttribute("t-key") &&
+      node.children.length === 1 &&
+      node.children[0].tagName !== "t" &&
+      !node.children[0].hasAttribute("t-key");
     if (shouldWarn) {
       console.warn(
         `Directive t-foreach should always be used with a t-key! (in template: '${ctx.templateName}')`
       );
     }
+
     nodeCopy.removeAttribute("t-foreach");
     qweb._compileNode(nodeCopy, ctx);
     ctx.dedent();

src/qweb/compilation_context.ts

@@ -1,4 +1,4 @@
-import { compileExpr, QWebVar } from "./expression_parser";
+import { compileExpr, QWebVar, QWebExprVar } from "./expression_parser";
 
 export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 //------------------------------------------------------------------------------
@@ -22,9 +22,10 @@ export class CompilationContext {
   shouldDefineUtils: boolean = false;
   shouldDefineRefs: boolean = false;
   shouldDefineResult: boolean = true;
+  shouldDefineSibling: boolean = true;
   shouldProtectContext: boolean = false;
   shouldTrackScope: boolean = false;
-  inLoop: boolean = false;
+  loopNumber: number = 0;
   inPreTag: boolean = false;
   templateName: string;
   allowMultipleRoots: boolean = false;
@@ -63,6 +64,9 @@ export class CompilationContext {
     if (this.shouldDefineResult) {
       this.code.unshift("    let result;");
     }
+    if (this.shouldDefineSibling) {
+      this.code.unshift("    let sibling = null;");
+    }
     if (this.shouldDefineRefs) {
       this.code.unshift("    context.__owl__.refs = context.__owl__.refs || {};");
     }
@@ -145,7 +149,7 @@ export class CompilationContext {
     this.addLine("}");
   }
 
-  getValue(val: any): any {
+  getValue(val: any): QWebExprVar | string {
     return val in this.variables ? this.getValue(this.variables[val]) : val;
   }
 

src/qweb/extensions.ts

@@ -40,44 +40,34 @@ QWeb.addDirective({
       extraArgs = args.slice(1, -1);
       return "";
     });
-    ctx.addIf(`!context['${handlerName}']`);
-    ctx.addLine(
-      `throw new Error('Missing handler \\'' + '${handlerName}' + \`\\' when evaluating template '${ctx.templateName.replace(
-        /`/g,
-        "'"
-      )}'\`)`
-    );
-    ctx.closeIf();
     let params = extraArgs ? `owner, ${ctx.formatExpression(extraArgs)}` : "owner";
-    if (mods.length > 0) {
-      let handler = `function (e) {`;
-      handler += mods
-        .map(function(mod) {
-          return MODS_CODE[mod];
-        })
-        .join("");
+    let handler = `function (e) {`;
+    handler += mods
+      .map(function(mod) {
+        return MODS_CODE[mod];
+      })
+      .join("");
+    if (handlerName) {
       if (!extraArgs) {
-        handler += `context['${handlerName}'].call(${params}, e);}`;
+        handler += `const fn = context['${handlerName}'];`;
+        handler += `if (fn) { fn.call(${params}, e); } else { context.${handlerName}; }`;
+        handler += `}`;
         ctx.addLine(
           `extra.handlers['${eventName}' + ${nodeID}] = extra.handlers['${eventName}' + ${nodeID}] || ${handler};`
         );
         ctx.addLine(`p${nodeID}.on['${eventName}'] = extra.handlers['${eventName}' + ${nodeID}];`);
       } else {
         const handlerKey = `handler${ctx.generateID()}`;
-        ctx.addLine(`const ${handlerKey} = context['${handlerName}'].bind(${params});`);
-        handler += `${handlerKey}(e);}`;
+        ctx.addLine(
+          `const ${handlerKey} = context['${handlerName}'] && context['${handlerName}'].bind(${params});`
+        );
+        handler += `if (${handlerKey}) { ${handlerKey}(e); } else { context.${value}; }`;
+        handler += `}`;
         ctx.addLine(`p${nodeID}.on['${eventName}'] = ${handler};`);
       }
     } else {
-      const handler = `context['${handlerName}'].bind(${params})`;
-      if (extraArgs) {
-        ctx.addLine(`p${nodeID}.on['${eventName}'] = ${handler};`);
-      } else {
-        ctx.addLine(
-          `extra.handlers['${eventName}' + ${nodeID}] = extra.handlers['${eventName}' + ${nodeID}] || ${handler};`
-        );
-        ctx.addLine(`p${nodeID}.on['${eventName}'] = extra.handlers['${eventName}' + ${nodeID}];`);
-      }
+      handler += "}";
+      ctx.addLine(`p${nodeID}.on['${eventName}'] = ${handler};`);
     }
   }
 });
@@ -209,17 +199,17 @@ QWeb.addDirective({
     ctx.addIf(`slot${slotKey}`);
     let parentNode = `c${ctx.parentNode}`;
     if (!ctx.parentNode) {
-        ctx.rootContext.shouldDefineResult = true;
-        ctx.rootContext.shouldDefineUtils = true;
-        parentNode = `children${ctx.nextID++}`;
-        ctx.addLine(`let ${parentNode}= []`);
-        ctx.addLine(`result = {}`);
+      ctx.rootContext.shouldDefineResult = true;
+      ctx.rootContext.shouldDefineUtils = true;
+      parentNode = `children${ctx.nextID++}`;
+      ctx.addLine(`let ${parentNode}= []`);
+      ctx.addLine(`result = {}`);
     }
     ctx.addLine(
       `slot${slotKey}.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: ${parentNode}, vars: extra.vars, parent: owner}));`
     );
     if (!ctx.parentNode) {
-        ctx.addLine(`Promise.all(extra.promises).then(() => utils.defineProxy(result, ${parentNode}[0]))`);
+      ctx.addLine(`utils.defineProxy(result, ${parentNode}[0]);`);
     }
     ctx.closeIf();
     return true;
@@ -271,3 +261,16 @@ QWeb.addDirective({
     ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers['${event}' + ${nodeID}];`);
   }
 });
+
+//------------------------------------------------------------------------------
+// t-key
+//------------------------------------------------------------------------------
+QWeb.addDirective({
+  name: "key",
+  priority: 45,
+  atNodeEncounter({ ctx, value }) {
+    let id = ctx.generateID();
+    ctx.addLine(`const nodeKey${id} = ${ctx.formatExpression(value)};`);
+    ctx.lastNodeKey = `nodeKey${id}`;
+  }
+});

src/qweb/qweb.ts

@@ -57,12 +57,19 @@ export interface Directive {
   finalize?(info: CompilationInfo): void;
 }
 
+interface QWebConfig {
+  templates?: string;
+  translateFn?(text: string): string;
+}
+
 //------------------------------------------------------------------------------
 // Const/global stuff/helpers
 //------------------------------------------------------------------------------
 
 const DISABLED_TAGS = ["input", "textarea", "button", "select", "option", "optgroup"];
 
+const TRANSLATABLE_ATTRS = ["label", "title", "placeholder", "alt"];
+
 const lineBreakRE = /[\r\n]/;
 const whitespaceRE = /\s+/g;
 
@@ -134,6 +141,7 @@ function parseXML(xml: string): Document {
 //------------------------------------------------------------------------------
 // QWeb rendering engine
 //------------------------------------------------------------------------------
+
 export class QWeb extends EventBus {
   templates: { [name: string]: Template };
   static utils = UTILS;
@@ -143,7 +151,7 @@ export class QWeb extends EventBus {
     name: 1,
     att: 1,
     attf: 1,
-    key: 1
+    translation: 1
   };
   static DIRECTIVES: Directive[] = [];
 
@@ -166,12 +174,16 @@ export class QWeb extends EventBus {
   recursiveFns = {};
 
   isUpdating: boolean = false;
+  translateFn?: QWebConfig["translateFn"];
 
-  constructor(data?: string) {
+  constructor(config: QWebConfig = {}) {
     super();
     this.templates = Object.create(QWeb.TEMPLATES);
-    if (data) {
-      this.addTemplates(data);
+    if (config.templates) {
+      this.addTemplates(config.templates);
+    }
+    if (config.translateFn) {
+      this.translateFn = config.translateFn;
     }
   }
 
@@ -418,6 +430,11 @@ export class QWeb extends EventBus {
         }
         text = text.replace(whitespaceRE, " ");
       }
+      if (this.translateFn) {
+        if ((node.parentNode as any).getAttribute("t-translation") !== "off") {
+          text = this.translateFn(text);
+        }
+      }
       if (ctx.parentNode) {
         if (node.nodeType === 3) {
           ctx.addLine(`c${ctx.parentNode}.push({text: \`${text}\`});`);
@@ -452,6 +469,8 @@ export class QWeb extends EventBus {
       fullName: string;
     }[] = [];
 
+    const finalizers: typeof validDirectives = [];
+
     // maybe this is not optimal: we iterate on all attributes here, and again
     // just after for each directive.
     for (let i = 0; i < attributes.length; i++) {
@@ -496,7 +515,11 @@ export class QWeb extends EventBus {
         }
       }
     }
+
     for (let { directive, value, fullName } of validDirectives) {
+      if (directive.finalize) {
+        finalizers.push({ directive, value, fullName });
+      }
       if (directive.atNodeEncounter) {
         const isDone = directive.atNodeEncounter({
           node,
@@ -506,6 +529,9 @@ export class QWeb extends EventBus {
           value
         });
         if (isDone) {
+          for (let { directive, value, fullName } of finalizers) {
+            directive.finalize!({ node, qweb: this, ctx, fullName, value });
+          }
           return;
         }
       }
@@ -564,10 +590,8 @@ export class QWeb extends EventBus {
       ctx.addLine(`utils.addNameSpace(vn${ctx.parentNode});`);
     }
 
-    for (let { directive, value, fullName } of validDirectives) {
-      if (directive.finalize) {
-        directive.finalize({ node, qweb: this, ctx, fullName, value });
-      }
+    for (let { directive, value, fullName } of finalizers) {
+      directive.finalize!({ node, qweb: this, ctx, fullName, value });
     }
   }
 
@@ -610,7 +634,11 @@ export class QWeb extends EventBus {
 
     for (let i = 0; i < attributes.length; i++) {
       let name = attributes[i].name;
-      const value = attributes[i].textContent!;
+      let value = attributes[i].textContent!;
+
+      if (this.translateFn && TRANSLATABLE_ATTRS.includes(name)) {
+        value = this.translateFn(value);
+      }
 
       // regular attributes
       if (!name.startsWith("t-") && !(<Element>node).getAttribute("t-attf-" + name)) {
@@ -638,7 +666,7 @@ export class QWeb extends EventBus {
       if (name.startsWith("t-att-")) {
         let attName = name.slice(6);
         const v = ctx.getValue(value);
-        let formattedValue = v.id || ctx.formatExpression(v);
+        let formattedValue = typeof v === "string" ? ctx.formatExpression(v) : v.id;
 
         if (attName === "class") {
           ctx.rootContext.shouldDefineUtils = true;
@@ -696,14 +724,7 @@ export class QWeb extends EventBus {
       }
     }
     let nodeID = ctx.generateID();
-    let nodeKey: any = (<Element>node).getAttribute("t-key");
-    if (nodeKey) {
-      ctx.addLine(`const nodeKey${nodeID} = ${ctx.formatExpression(nodeKey)}`);
-      nodeKey = `nodeKey${nodeID}`;
-      ctx.lastNodeKey = nodeKey;
-    } else {
-      nodeKey = nodeID;
-    }
+    let nodeKey = ctx.lastNodeKey || nodeID;
     const parts = [`key:${nodeKey}`];
     if (attrs.length + tattrs.length > 0) {
       parts.push(`attrs:{${attrs.join(",")}}`);

src/router/router.ts

@@ -148,7 +148,7 @@ export class Router {
   //--------------------------------------------------------------------------
 
   private setUrlFromPath(path: string) {
-    const separator = this.mode === "hash" ? "/" : "";
+    const separator = this.mode === "hash" ? location.pathname : "";
     const url = location.origin + separator + path;
     if (url !== window.location.href) {
       window.history.pushState({}, path, url);

src/store.ts

@@ -104,11 +104,11 @@ export function useStore(selector, options: SelectorOptions = {}): any {
       return true;
     }
     return false;
-  })
+  });
 
   useContextWithCB(store, component, function(): Promise<void> | void {
     let shouldRender = false;
-    updateFunctions.forEach(function (updateFn) {
+    updateFunctions.forEach(function(updateFn) {
       shouldRender = updateFn() || shouldRender;
     });
     if (shouldRender) {

src/utils.ts

@@ -5,7 +5,7 @@
  *
  * - whenReady
  * - loadJS
- * - loadTemplates
+ * - loadFile
  * - escape
  * - debounce
  */
@@ -43,7 +43,7 @@ export function loadJS(url: string): Promise<void> {
   return promise;
 }
 
-export async function loadTemplates(url: string): Promise<string> {
+export async function loadFile(url: string): Promise<string> {
   const result = await fetch(url);
   if (!result.ok) {
     throw new Error("Error while fetching xml templates");

src/vdom/vdom.ts

@@ -176,18 +176,10 @@ export function init(modules: Array<Partial<Module>>, domApi?: DOMAPI) {
       }
       vnode.elm = api.createComment(vnode.text as string);
     } else if (sel !== undefined) {
-      // Parse selector
-      const hashIdx = sel.indexOf("#");
-      const dotIdx = sel.indexOf(".", hashIdx);
-      const hash = hashIdx > 0 ? hashIdx : sel.length;
-      const dot = dotIdx > 0 ? dotIdx : sel.length;
-      const tag = hashIdx !== -1 || dotIdx !== -1 ? sel.slice(0, Math.min(hash, dot)) : sel;
       const elm = (vnode.elm =
         isDef(data) && isDef((i = (data as VNodeData).ns))
-          ? api.createElementNS(i, tag)
-          : api.createElement(tag));
-      if (hash < dot) elm.setAttribute("id", sel.slice(hash + 1, dot));
-      if (dotIdx > 0) elm.setAttribute("class", sel.slice(dot + 1).replace(/\./g, " "));
+          ? api.createElementNS(i, sel)
+          : api.createElement(sel));
       for (i = 0, iLen = cbs.create.length; i < iLen; ++i) cbs.create[i](emptyNode, vnode);
       if (array(children)) {
         for (i = 0, iLen = children.length; i < iLen; ++i) {
@@ -565,13 +557,15 @@ type ArrayOrElement<T> = T | T[];
 type VNodeChildren = ArrayOrElement<VNodeChildElement>;
 
 export function addNS(data: any, children: VNodes | undefined, sel: string | undefined): void {
+  if (sel === "dummy") {
+    // we do not need to add the namespace on dummy elements, they come from a
+    // subcomponent, which will handle the namespace itself
+    return;
+  }
   data.ns = "http://www.w3.org/2000/svg";
   if (sel !== "foreignObject" && children !== undefined) {
     for (let i = 0, iLen = children.length; i < iLen; ++i) {
       const child = children[i];
-      if (child === null) {
-        continue;
-      }
       let childData = child.data;
       if (childData !== undefined) {
         addNS(childData, (child as VNode).children as VNodes, child.sel);

tests/__snapshots__/animations.test.ts.snap

@@ -7,39 +7,39 @@ exports[`animations t-transition combined with component 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let owner = context;
+    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let def3;
-    let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
-    let _2_index = c1.length;
-    c1.push(null);
-    let props4 = {};
-    if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
-        if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
-            def3 = w4.__owl__.currentFiber.promise;
-        } else {
-            w4.destroy();
-            w4 = false;
-        }
+    let templateId3 = \`__4__\`;
+    let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
+    let props3 = {};
+    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+        w3.destroy();
+        w3 = false;
     }
-    if (!w4) {
-        let componentKey4 = \`Child\`;
-        let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
-        if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
-        w4 = new W4(parent, props4);
-        parent.__owl__.cmap[4] = w4.__owl__.id;
-        def3 = w4.__prepare(extra.fiber, undefined, undefined);
-        def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
-          w4.destroy();
-        };
-        utils.transitionRemove(vn, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+    if (w3) {
+        w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
+        let pvnode = w3.__owl__.pvnode;
+        c1.push(pvnode);
     } else {
-        def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
-        def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+        let componentKey3 = \`Child\`;
+        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+        w3 = new W3(parent, props3);
+        parent.__owl__.cmap[templateId3] = w3.__owl__.id;
+        let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
+        let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w3.destroy();
+        };
+        utils.transitionRemove(vn, 'chimay', finalize);}}});
+        const fiber = w3.__owl__.currentFiber;
+        def2.then(function () {if (w3.__owl__.isDestroyed) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        c1.push(pvnode);
+        w3.__owl__.pvnode = pvnode;
     }
-    extra.promises.push(def3);
+    sibling = w3.__owl__.currentFiber || sibling;
     return vn1;
 }"
 `;
@@ -51,40 +51,40 @@ exports[`animations t-transition combined with t-component and t-if 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let owner = context;
+    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     if (context['state'].display) {
         //COMPONENT
-        let def3;
-        let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
-        let _2_index = c1.length;
-        c1.push(null);
-        let props4 = {};
-        if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
-            if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
-                def3 = w4.__owl__.currentFiber.promise;
-            } else {
-                w4.destroy();
-                w4 = false;
-            }
+        let templateId3 = \`__4__\`;
+        let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
+        let props3 = {};
+        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+            w3.destroy();
+            w3 = false;
         }
-        if (!w4) {
-            let componentKey4 = \`Child\`;
-            let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
-            if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
-            w4 = new W4(parent, props4);
-            parent.__owl__.cmap[4] = w4.__owl__.id;
-            def3 = w4.__prepare(extra.fiber, undefined, undefined);
-            def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
-          w4.destroy();
-        };
-        utils.transitionRemove(vn, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+        if (w3) {
+            w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
+            let pvnode = w3.__owl__.pvnode;
+            c1.push(pvnode);
         } else {
-            def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
-            def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+            let componentKey3 = \`Child\`;
+            let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+            if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+            w3 = new W3(parent, props3);
+            parent.__owl__.cmap[templateId3] = w3.__owl__.id;
+            let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
+            let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w3.destroy();
+        };
+        utils.transitionRemove(vn, 'chimay', finalize);}}});
+            const fiber = w3.__owl__.currentFiber;
+            def2.then(function () {if (w3.__owl__.isDestroyed) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            c1.push(pvnode);
+            w3.__owl__.pvnode = pvnode;
         }
-        extra.promises.push(def3);
+        sibling = w3.__owl__.currentFiber || sibling;
     }
     return vn1;
 }"
@@ -94,6 +94,7 @@ exports[`animations t-transition with no delay/duration 1`] = `
 "function anonymous(context,extra
 ) {
     let utils = this.constructor.utils;
+    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('span', p1, c1);
@@ -114,6 +115,7 @@ exports[`animations t-transition, on a simple node (insert) 1`] = `
 "function anonymous(context,extra
 ) {
     let utils = this.constructor.utils;
+    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('span', p1, c1);

tests/animations.test.ts

@@ -251,11 +251,11 @@ describe("animations", () => {
     widget.state.display = false;
     patchNextFrame(cb => {
       expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="4">blue</span></div>'
+        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="__4__">blue</span></div>'
       );
       cb();
       expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="4">blue</span></div>'
+        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__4__">blue</span></div>'
       );
       def.resolve();
     });

tests/component/__snapshots__/props_validation.test.ts.snap

@@ -1,9 +1,5 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`default props default values are also set whenever component is updated 1`] = `"<div>1</div>"`;
-
-exports[`default props default values are also set whenever component is updated 2`] = `"<div>4</div>"`;
-
 exports[`props validation props are validated in dev mode (code snapshot) 1`] = `
 "function anonymous(context,extra
 ) {
@@ -11,38 +7,36 @@ exports[`props validation props are validated in dev mode (code snapshot) 1`] =
     let QWeb = this.constructor;
     let parent = context;
     let owner = context;
+    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let def3;
-    let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
-    let _2_index = c1.length;
-    c1.push(null);
-    let props4 = {message:1};
-    if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
-        if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
-            def3 = w4.__owl__.currentFiber.promise;
-        } else {
-            w4.destroy();
-            w4 = false;
-        }
+    let templateId3 = \`__4__\`;
+    let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
+    let props3 = {message:1};
+    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+        w3.destroy();
+        w3 = false;
     }
-    if (!w4) {
-        let componentKey4 = \`Child\`;
-        let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
-        if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
-        utils.validateProps(W4, props4)
-        w4 = new W4(parent, props4);
-        parent.__owl__.cmap[4] = w4.__owl__.id;
-        def3 = w4.__prepare(extra.fiber, undefined, undefined);
-        def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+    if (w3) {
+        w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
+        let pvnode = w3.__owl__.pvnode;
+        c1.push(pvnode);
     } else {
-        utils.validateProps(w4.constructor, props4)
-        def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
-        def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+        let componentKey3 = \`Child\`;
+        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+        w3 = new W3(parent, props3);
+        parent.__owl__.cmap[templateId3] = w3.__owl__.id;
+        let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
+        let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});
+        const fiber = w3.__owl__.currentFiber;
+        def2.then(function () {if (w3.__owl__.isDestroyed) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        c1.push(pvnode);
+        w3.__owl__.pvnode = pvnode;
     }
-    extra.promises.push(def3);
+    sibling = w3.__owl__.currentFiber || sibling;
     return vn1;
 }"
 `;

tests/component/props_validation.test.ts

@@ -1,5 +1,6 @@
 import { Component, Env } from "../../src/component/component";
-import { makeTestFixture, makeTestEnv } from "../helpers";
+import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
+import { useState } from "../../src/hooks";
 import { QWeb } from "../../src/qweb";
 import { xml } from "../../src/tags";
 
@@ -321,6 +322,79 @@ describe("props validation", () => {
       QWeb.utils.validateProps(TestWidget, { message: null });
     }).toThrow();
   });
+
+  test("missing required boolean prop causes an error", async () => {
+    class TestWidget extends Widget {
+      static props = ["p"];
+      static template = xml`<span><t t-if="props.p">hey</t></span>`;
+    }
+
+    class App extends Widget {
+      static template = xml`<div><TestWidget/></div>`;
+      static components = { TestWidget };
+    }
+
+    const w = new App(env, {});
+    let error;
+    try {
+      await w.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Missing props 'p' (component 'TestWidget')");
+  });
+
+  test("props are validated whenever component is updated", async () => {
+    let error;
+    class TestWidget extends Component<any, any> {
+      static props = { p: { type: Number } };
+      static template = xml`<div><t t-esc="props.p"/></div>`;
+
+      async __updateProps() {
+        try {
+          await Component.prototype.__updateProps.apply(this, arguments);
+        } catch(e) {
+          error = e;
+        }
+      }
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`<div><TestWidget p="state.p"/></div>`;
+      static components = { TestWidget };
+      state: any = useState({ p: 1 });
+    }
+
+    const w = new Parent(env);
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
+
+    w.state.p = undefined;
+    await nextTick();
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Missing props 'p' (component 'TestWidget')");
+  });
+
+  test("default values are applied before validating props at update", async () => {
+    class TestWidget extends Component<any, any> {
+      static props = { p: { type: Number } };
+      static template = xml`<div><t t-esc="props.p"/></div>`;
+      static defaultProps = { p: 4 };
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`<div><TestWidget p="state.p"/></div>`;
+      static components = { TestWidget };
+      state: any = useState({ p: 1 });
+    }
+
+    const w = new Parent(env);
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
+
+    w.state.p = undefined;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
+  });
 });
 
 describe("default props", () => {
@@ -336,20 +410,38 @@ describe("default props", () => {
 
   test("default values are also set whenever component is updated", async () => {
     class TestWidget extends Widget {
+      static template = xml`<div><t t-esc="props.p"/></div>`;
       static defaultProps = { p: 4 };
     }
-    env.qweb.addTemplates(`
-        <templates>
-            <div t-name="TestWidget"><t t-esc="props.p"/></div>
-        </templates>`);
+    class Parent extends Widget {
+      static template = xml`<div><TestWidget p="state.p"/></div>`;
+      static components = { TestWidget };
+      state: any = useState({ p: 1 });
+    }
 
-    const w = new TestWidget(env, { p: 1 });
+    const w = new Parent(env);
     await w.mount(fixture);
-    expect(fixture.innerHTML).toMatchSnapshot();
-    const fiber = w.__createFiber(false, undefined, undefined, undefined);
-    await w.__updateProps({}, fiber);
-    await w.render();
-    expect(w.props.p).toBe(4);
-    expect(fixture.innerHTML).toMatchSnapshot();
+    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
+
+    w.state.p = undefined;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
+  });
+
+  test("can set default required boolean values", async () => {
+    class TestWidget extends Widget {
+      static props = ["p", "q"];
+      static defaultProps = { p: true, q: false };
+      static template = xml`<span><t t-if="props.p">hey</t><t t-if="!props.q">hey</t></span>`;
+    }
+
+    class App extends Widget {
+      static template = xml`<div><TestWidget/></div>`;
+      static components = { TestWidget };
+    }
+
+    const w = new App(env, {});
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><span>heyhey</span></div>");
   });
 });

tests/context.test.ts

@@ -1,4 +1,4 @@
-import { makeTestEnv, makeTestFixture, nextTick } from "./helpers";
+import { makeDeferred, makeTestEnv, makeTestFixture, nextTick } from "./helpers";
 import { Component, Env } from "../src/component/component";
 import { Context, useContext } from "../src/context";
 import { xml } from "../src/tags";
@@ -173,4 +173,52 @@ describe("Context", () => {
     // event
     expect(testContext.subscriptions.update.length).toBe(0);
   });
+
+  test("concurrent renderings", async () => {
+    const testContext = new Context({ x: { n: 1 }, key: "x" });
+    const def = makeDeferred();
+    let stateC;
+    class ComponentC extends Component<any, any> {
+      static template = xml`<span><t t-esc="context[props.key].n"/><t t-esc="state.x"/></span>`;
+      context = useContext(testContext);
+      state = useState({ x: "a" });
+
+      constructor(parent, props) {
+        super(parent, props);
+        stateC = this.state;
+      }
+    }
+    class ComponentB extends Component<any, any> {
+      static components = { ComponentC };
+      static template = xml`<p><ComponentC key="props.key"/></p>`;
+
+      willUpdateProps() {
+        return def;
+      }
+    }
+    class ComponentA extends Component<any, any> {
+      static components = { ComponentB };
+      static template = xml`<div><ComponentB key="context.key"/></div>`;
+      context = useContext(testContext);
+    }
+
+    const component = new ComponentA(env);
+    await component.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
+    testContext.state.key = "y";
+    testContext.state.y = { n: 2 };
+    delete testContext.state.x;
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
+    stateC.x = "b";
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
+    def.resolve();
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe("<div><p><span>2b</span></p></div>");
+  });
 });

tests/doc_link_checker.test.ts

@@ -6,35 +6,9 @@
  */
 import * as fs from "fs";
 
-const LINK_REGEXP = /\[([^\[]+)\]\(([^\)]+)\)/g;
-const HEADING_REGEXP = /\n(#+\s*)(.*)/g;
-
-// files to be checked
-function getFiles(): string[] {
-  const DOCFILES = fs.readdirSync("doc").map(f => `doc/${f}`);
-  const MAINREADME = "README.md";
-  return DOCFILES.concat(MAINREADME);
-}
-
-test("All markdown links work", () => {
-  let linkNumber = 0;
-  let invalidLinkNumber = 0;
-  const files = getFiles();
-  const data = readDocData(files);
-  for (let file of data) {
-    for (let link of file.links) {
-      // DEBUG: uncomment next line
-      // console.warn(`Checking "${link.name}" in "${file.name}"`);
-      linkNumber++;
-      if (!isLinkValid(link, file, data)) {
-        console.warn(`Invalid Link: "${link.name}" in "${file.name}"`);
-        invalidLinkNumber++;
-      }
-    }
-  }
-  expect(invalidLinkNumber).toBe(0);
-  expect(linkNumber).toBeGreaterThan(10);
-});
+//--------------------------------------------------------------------------
+// Helpers
+//--------------------------------------------------------------------------
 
 interface MarkDownLink {
   name: string;
@@ -48,34 +22,130 @@ interface MarkDownSection {
 
 interface FileData {
   name: string;
+  path: string[];
+  fullName: string
   links: MarkDownLink[];
   sections: MarkDownSection[];
 }
 
-function isLinkValid(link: MarkDownLink, current: FileData, files: FileData[]): boolean {
-  const parts = link.link.split("#");
-  const currentParts = current.name.split("/");
-  const path = currentParts.length > 1 ? currentParts[0] + "/" : "";
-  const fullName = path + parts[0];
-  if (parts.length === 1) {
-    // no # in url
-    if (parts[0].endsWith(".md")) {
-      // it is a local md file
-      if (!files.find(f => f.name === fullName)) {
-        return false;
+const LINK_REGEXP = /\[([^\[]+)\]\(([^\)]+)\)/g;
+const HEADING_REGEXP = /\n(#+\s*)(.*)/g;
+
+
+
+export function addMardownData(fileData): void {
+    const sep = fileData.path.length > 0 ? '/' : '';
+    const fullName = fileData.path.join('/') + sep + fileData.name;
+    const content = fs.readFileSync(fullName, { encoding: "utf8" });
+    let m;
+    // get links info
+    do {
+      m = LINK_REGEXP.exec(content);
+      if (m) {
+        fileData.links.push({ name: m[0], link: m[2] });
       }
-    }
-  } else {
-    const file = parts[0] === "" ? current : files.find(f => f.name === fullName);
-    if (!file) {
-      return false;
-    }
-    if (!file.sections.find(s => s.slug === parts[1])) {
-      return false;
-    }
-  }
-  return true;
+    } while (m);
+    // get sections info
+    do {
+      m = HEADING_REGEXP.exec(content);
+      if (m) {
+        fileData.sections.push({ name: m[0], slug: slugify(m[2]) });
+      }
+    } while (m);
 }
+
+
+/**
+ * Returns a list of FileData corresponding to all files that need to be
+ * validated.
+ */
+function getFiles(path: string[] = []): FileData[] {
+  if (path.length === 0) {
+    const baseFiles: FileData[] = [
+      { name: "README.md", path: [], links: [], sections: [], fullName: "README.md" },
+      { name: "roadmap.md", path: [], links: [], sections: [], fullName: "roadmap.md" }
+    ];
+    const rest = getFiles(["doc"]);
+    const result = baseFiles.concat(rest);
+    result.forEach(addMardownData);
+    return result;
+  }
+  const files = fs.readdirSync(path.join("/"), { withFileTypes: true }).map(f => {
+    if (f.isDirectory()) {
+      return getFiles(path.concat(f.name));
+    }
+    const fullName = path.join('/') + (path.length > 0 ? '/' : '') + f.name;
+    return [
+      {
+        name: f.name,
+        path,
+        links: [],
+        sections: [],
+        fullName
+      }
+    ];
+  });
+  return Array.prototype.concat(...files);
+}
+
+const LOCAL_FILES = ['LICENSE'];
+export function isLinkValid(link: MarkDownLink, current: FileData, files: FileData[]): boolean {
+  if (link.link.startsWith("http")) {
+    // no check on external links
+    return true;
+  }
+    // Step 1: extract path, name, hash
+    //      path = ['doc', 'architecture]
+    //      name = 'rendering.md'
+    //      hash = 'blabla' (or '' if no hash)
+
+    const parts = link.link.split('#');
+    const hash = parts[1] || '';
+    let name;
+    let path;
+    if (parts[0]) {
+        let temp = parts[0].split('/');
+        name = temp[temp.length - 1];
+        temp.splice(-1);
+        path = current.path.slice();
+        for (let elem of temp) {
+            if (elem === '..') {
+                path.splice(-1);
+             } else if (elem !== '.') {
+                 path.push(elem);
+             }
+        }
+    } else {
+        // there are no file name, so this is a relative link to the current file
+        name = current.name;
+        path = current.path;
+    }
+
+    // Step 2: build normalized link file name
+    const linkFullName = path.join('/') + (path.length > 0 ? '/' : '') + name;
+
+    // Step 3: check link name against white list of local files
+    if (LOCAL_FILES.includes(linkFullName)) {
+        return true;
+    }
+
+    // Step 4: check if there is a matching file
+    let target: FileData | undefined = files.find(f => f.fullName === linkFullName);
+    if (!target) {
+        return false;
+    }
+
+    // Step 5: if necessary, check if there is a corresponding link inside the target
+    // link name
+    if (hash) {
+        if (!target.sections.find(s => s.slug === hash)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 // adapted from https://medium.com/@mhagemann/the-ultimate-way-to-slugify-a-url-string-in-javascript-b8e4a0d849e1
 function slugify(str) {
   const a = "àáäâãåăæçèéëêǵḧìíïîḿńǹñòóöôœøṕŕßśșțùúüûǘẃẍÿź·_,:;";
@@ -94,33 +164,25 @@ function slugify(str) {
     .replace(/-+$/, ""); // Trim - from end of text
 }
 
-function readDocData(files: string[]): FileData[] {
-  const result: FileData[] = [];
 
-  for (let file of files) {
-    const fileData: FileData = {
-      name: file,
-      links: [],
-      sections: []
-    };
-    const content = fs.readFileSync(file, { encoding: "utf8" });
-    let m;
-    // get links info
-    do {
-      m = LINK_REGEXP.exec(content);
-      if (m) {
-        fileData.links.push({ name: m[0], link: m[2] });
-      }
-    } while (m);
-    // get sections info
-    do {
-      m = HEADING_REGEXP.exec(content);
-      if (m) {
-        fileData.sections.push({ name: m[0], slug: slugify(m[2]) });
-      }
-    } while (m);
 
-    result.push(fileData);
-  }
-  return result;
-}
+//--------------------------------------------------------------------------
+// Test
+//--------------------------------------------------------------------------
+
+test("All markdown links work", () => {
+    let linkNumber = 0;
+    let invalidLinkNumber = 0;
+    const data = getFiles();
+    for (let file of data) {
+      for (let link of file.links) {
+        linkNumber++;
+        if (!isLinkValid(link, file, data)) {
+          console.warn(`Invalid Link: "${link.name}" in "${file.name}"`);
+          invalidLinkNumber++;
+        }
+    }
+    }
+    expect(invalidLinkNumber).toBe(0);
+    expect(linkNumber).toBeGreaterThan(10);
+});

tests/helpers.ts

@@ -1,10 +1,16 @@
-import { Env } from "../src/component/component";
+import { Env, scheduler } from "../src/component/component";
 import { EvalContext, QWeb } from "../src/qweb/qweb";
 import { patch } from "../src/vdom";
 import "../src/qweb/base_directives";
 import "../src/qweb/extensions";
 import "../src/component/directive";
 
+// modifies scheduler to make it faster to test components
+scheduler.requestAnimationFrame = function(callback: FrameRequestCallback) {
+  setTimeout(callback, 1);
+  return 1;
+};
+
 // Some static cleanup
 let nextSlotId;
 let slots;
@@ -30,8 +36,10 @@ export function nextMicroTick(): Promise<void> {
   return Promise.resolve();
 }
 
-export function nextTick(): Promise<void> {
-  return new Promise(resolve => setTimeout(resolve));
+export async function nextTick(): Promise<void> {
+  return new Promise(function(resolve) {
+    setTimeout(() => scheduler.requestAnimationFrame(() => resolve()));
+  });
 }
 
 export function makeTestFixture() {

tests/misc/async_root.test.ts

@@ -0,0 +1,189 @@
+import { AsyncRoot } from "../../src/misc/async_root";
+import { useState } from "../../src/hooks";
+import { xml } from "../../src/tags";
+import { makeDeferred, makeTestFixture, makeTestEnv, nextTick } from "../helpers";
+import { Env, Component } from "../../src/component/component";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: a WEnv, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("Asyncroot", () => {
+  test("delayed component with AsyncRoot component", async () => {
+    let def;
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+    }
+    class AsyncChild extends Child {
+      willUpdateProps() {
+        return def;
+      }
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`
+          <div>
+            <button t-on-click="updateApp">Update App State</button>
+            <div class="children">
+              <Child val="state.val"/>
+              <AsyncRoot>
+                  <AsyncChild val="state.val"/>
+              </AsyncRoot>
+            </div>
+          </div>`;
+      static components = { Child, AsyncChild, AsyncRoot };
+      state = useState({ val: 0 });
+
+      updateApp() {
+        this.state.val++;
+      }
+    }
+
+    const parent = new Parent(env);
+    await parent.mount(fixture);
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0</span><span>0</span>");
+
+    // click on button to increment Parent counter
+    def = makeDeferred();
+    fixture.querySelector("button")!.click();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>0</span>");
+
+    def.resolve();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>1</span>");
+  });
+
+  test("fast component with AsyncRoot", async () => {
+    let def;
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+    }
+    class AsyncChild extends Child {
+      willUpdateProps() {
+        return def;
+      }
+    }
+
+    class Parent extends Component<any, any> {
+      static template = xml`
+          <div>
+            <button t-on-click="updateApp">Update App State</button>
+            <div class="children">
+              <AsyncRoot>
+                <Child val="state.val"/>
+              </AsyncRoot>
+              <AsyncChild val="state.val"/>
+            </div>
+          </div>`;
+      static components = { Child, AsyncChild, AsyncRoot };
+      state = useState({ val: 0 });
+
+      updateApp() {
+        this.state.val++;
+      }
+    }
+
+    const parent = new Parent(env);
+    await parent.mount(fixture);
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0</span><span>0</span>");
+
+    // click on button to increment Parent counter
+    def = makeDeferred();
+    fixture.querySelector("button")!.click();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>0</span>");
+
+    def.resolve();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>1</span>");
+  });
+
+  test("asyncroot component: mixed re-renderings", async () => {
+    let def;
+    class Child extends Component<any, any> {
+      static template = xml`
+        <span t-on-click="increment">
+          <t t-esc="state.val"/>/<t t-esc="props.val"/>
+        </span>`;
+      state = useState({ val: 0 });
+
+      increment() {
+        this.state.val++;
+      }
+    }
+    class AsyncChild extends Child {
+      willUpdateProps() {
+        return def;
+      }
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`
+        <div>
+          <button t-on-click="updateApp">Update App State</button>
+          <div class="children">
+            <Child val="state.val"/>
+            <AsyncRoot>
+              <AsyncChild val="state.val"/>
+            </AsyncRoot>
+          </div>
+        </div>`;
+      static components = { Child, AsyncChild, AsyncRoot };
+      state = useState({ val: 0 });
+
+      updateApp() {
+        this.state.val++;
+      }
+    }
+
+    const parent = new Parent(env);
+    await parent.mount(fixture);
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0/0</span><span>0/0</span>");
+
+    // click on button to increment Parent counter
+    def = makeDeferred();
+    fixture.querySelector("button")!.click();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0/1</span><span>0/0</span>");
+
+    // click on each Child to increment their local counter
+    const children = parent.el!.querySelectorAll("span");
+    children[0]!.click();
+    await nextTick();
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>0/0</span>");
+
+    children[1]!.click();
+    await nextTick();
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>0/0</span>");
+
+    // finalize first re-rendering (coming from the props update)
+    def.resolve();
+    await nextTick();
+
+    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>1/1</span>");
+  });
+});

tests/qweb/qweb.test.ts

@@ -1,5 +1,6 @@
 import { QWeb } from "../../src/qweb/index";
-import { normalize, renderToDOM, renderToString, trim, nextTick } from "../helpers";
+import { nextTick, normalize, renderToDOM, renderToString, trim } from "../helpers";
+import { patch } from "../../src/vdom";
 
 //------------------------------------------------------------------------------
 // Setup and helpers
@@ -79,19 +80,12 @@ describe("error handling", () => {
     expect(() => qweb.addTemplate("test", "<div/>")).toThrow("already defined");
   });
 
-  test("loadTemplates throw if parser error", () => {
+  test("addTemplates throw if parser error", () => {
     expect(() => {
       qweb.addTemplates("<templates><abc>></templates>");
     }).toThrow("Invalid XML in template");
   });
 
-  test("nice error when t-on-directive is evaluated with a missing handler", () => {
-    qweb.addTemplate("templatename", `<div t-on-click="somemethod"></div>`);
-    expect(() => qweb.render("templatename", {}, { handlers: [] })).toThrow(
-      "Missing handler 'somemethod' when evaluating template 'templatename'"
-    );
-  });
-
   test("nice error when t-on is evaluated with a missing event", () => {
     qweb.addTemplate("templatename", `<div t-on="somemethod"></div>`);
     expect(() => qweb.render("templatename", { someMethod() {} }, { handlers: [] })).toThrow(
@@ -328,6 +322,61 @@ describe("t-if", () => {
     };
     expect(normalize(renderToString(qweb, "test", context))).toBe("<div>andormgtnlt</div>");
   });
+
+  test("t-esc with t-if", () => {
+    qweb.addTemplate("test", `<div><t t-if="true" t-esc="'x'"/></div>`);
+    expect(renderToString(qweb, "test")).toBe("<div>x</div>");
+  });
+
+  test("t-esc with t-elif", () => {
+    qweb.addTemplate("test", `<div><t t-if="false">abc</t><t t-else="1" t-esc="'x'"/></div>`);
+    expect(renderToString(qweb, "test")).toBe("<div>x</div>");
+  });
+
+  test("t-set, then t-if", () => {
+    qweb.addTemplate(
+      "test",
+      `
+      <div>
+        <t t-set="title" t-value="'test'"/>
+        <t t-if="title"><t t-esc="title"/></t>
+      </div>`
+    );
+    const result = renderToString(qweb, "test");
+    const expected = `<div>test</div>`;
+    expect(result).toBe(expected);
+  });
+
+  test("t-set, then t-if, part 2", () => {
+    qweb.addTemplate(
+      "test",
+      `
+        <div>
+            <t t-set="y" t-value="true"/>
+            <t t-set="x" t-value="y"/>
+            <span t-if="x">COUCOU</span>
+        </div>`
+    );
+    const result = renderToString(qweb, "test");
+    const expected = `<div><span>COUCOU</span></div>`;
+    expect(result).toBe(expected);
+  });
+
+  test("t-set, then t-elif, part 3", () => {
+    qweb.addTemplate(
+      "test",
+      `
+        <div>
+            <t t-set="y" t-value="false"/>
+            <t t-set="x" t-value="y"/>
+            <span t-if="x">AAA</span>
+            <span t-elif="!x">BBB</span>
+        </div>`
+    );
+    const result = renderToString(qweb, "test");
+    const expected = `<div><span>BBB</span></div>`;
+    expect(result).toBe(expected);
+  });
 });
 
 describe("attributes", () => {
@@ -611,7 +660,7 @@ describe("t-call (template calling", () => {
     `);
     const expected = "<div><span>hey</span></div>";
     expect(renderToString(qweb, "recursive")).toBe(expected);
-    const recursiveFn = Object.values(qweb.recursiveFns)[0];
+    const recursiveFn = Object.values(qweb.recursiveFns)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -639,7 +688,7 @@ describe("t-call (template calling", () => {
     expect(renderToString(qweb, "Parent", { root }, { fiber: { vars: {}, scope: {} } })).toBe(
       expected
     );
-    const recursiveFn = Object.values(qweb.recursiveFns)[0];
+    const recursiveFn = Object.values(qweb.recursiveFns)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -666,7 +715,7 @@ describe("t-call (template calling", () => {
     const expected =
       "<div><div><p>a</p><div><p>b</p><div><p>d</p></div></div><div><p>c</p></div></div></div>";
     expect(renderToString(qweb, "Parent", { root }, { fiber: {} })).toBe(expected);
-    const recursiveFn = Object.values(qweb.recursiveFns)[0];
+    const recursiveFn = Object.values(qweb.recursiveFns)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -749,6 +798,23 @@ describe("foreach", () => {
     expect(Object.keys(context).length).toBe(0);
   });
 
+  test("t-foreach in t-forach", () => {
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <t t-foreach="numbers" t-as="number">
+          <t t-foreach="letters" t-as="letter">
+            [<t t-esc="number"/><t t-esc="letter"/>]
+          </t>
+        </t>
+      </div>`
+    );
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    expect(renderToString(qweb, "test", context)).toBe(
+      "<div> [1a]  [1b]  [2a]  [2b]  [3a]  [3b] </div>"
+    );
+  });
+
   test("throws error if invalid loop expression", () => {
     qweb.addTemplate(
       "test",
@@ -772,6 +838,9 @@ describe("foreach", () => {
     );
     renderToString(qweb, "test");
     expect(console.warn).toHaveBeenCalledTimes(1);
+    expect(console.warn).toHaveBeenCalledWith(
+      "Directive t-foreach should always be used with a t-key! (in template: 'test')"
+    );
     console.warn = consoleWarn;
   });
 });
@@ -975,6 +1044,35 @@ describe("t-on", () => {
     (<HTMLElement>node).click();
   });
 
+  test("t-on with inline statement", () => {
+    qweb.addTemplate("test", `<button t-on-click="state.counter++">Click</button>`);
+    let owner = {
+      state: {
+        counter: 0
+      }
+    };
+    const node = renderToDOM(qweb, "test", owner, { handlers: [] });
+    expect(owner.state.counter).toBe(0);
+    (<HTMLElement>node).click();
+    expect(owner.state.counter).toBe(1);
+  });
+
+  test("t-on with inline statement (function call)", () => {
+    qweb.addTemplate("test", `<button t-on-click="state.incrementCounter(2)">Click</button>`);
+    let owner = {
+      state: {
+        counter: 0,
+        incrementCounter: inc => {
+          owner.state.counter += inc;
+        }
+      }
+    };
+    const node = renderToDOM(qweb, "test", owner, { handlers: [] });
+    expect(owner.state.counter).toBe(0);
+    (<HTMLElement>node).click();
+    expect(owner.state.counter).toBe(2);
+  });
+
   test("t-on with prevent and/or stop modifiers", async () => {
     expect.assertions(7);
     qweb.addTemplate(
@@ -1121,6 +1219,24 @@ describe("t-on", () => {
     expect(steps).toEqual([1, 2]);
   });
 
+  test("t-on with empty handler (only modifiers)", () => {
+    expect.assertions(2);
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <button t-on-click.prevent="">Button</button>
+      </div>`
+    );
+    const node = renderToDOM(qweb, "test", {}, { handlers: [] });
+
+    node.addEventListener("click", e => {
+      expect(e.defaultPrevented).toBe(true);
+    });
+
+    const button = (<HTMLElement>node).getElementsByTagName("button")[0];
+    button.click();
+  });
+
   test("t-on combined with t-esc", async () => {
     expect.assertions(3);
     qweb.addTemplate("test", `<div><button t-on-click="onClick" t-esc="text"/></div>`);
@@ -1193,12 +1309,12 @@ describe("t-ref", () => {
 
 describe("loading templates", () => {
   test("can initialize qweb with a string", () => {
-    const data = `
+    const templates = `
       <?xml version="1.0" encoding="UTF-8"?>
       <templates id="template" xml:space="preserve">
         <div t-name="hey">jupiler</div>
       </templates>`;
-    const qweb = new QWeb(data);
+    const qweb = new QWeb({ templates });
     expect(renderToString(qweb, "hey")).toBe("<div>jupiler</div>");
   });
 
@@ -1407,3 +1523,84 @@ describe("properly support svg", () => {
     );
   });
 });
+
+describe("translation support", () => {
+  test("can translate node content", () => {
+    const translations = {
+      word: "mot"
+    };
+    const translateFn = expr => translations[expr] || expr;
+    const qweb = new QWeb({ translateFn });
+    qweb.addTemplate("test", "<div>word</div>");
+    expect(renderToString(qweb, "test")).toBe("<div>mot</div>");
+  });
+
+  test("does not translate node content if disabled", () => {
+    const translations = {
+      word: "mot"
+    };
+    const translateFn = expr => translations[expr] || expr;
+    const qweb = new QWeb({ translateFn });
+    qweb.addTemplate(
+      "test",
+      `
+      <div>
+        <span>word</span>
+        <span t-translation="off">word</span>
+      </div>`
+    );
+    expect(renderToString(qweb, "test")).toBe("<div><span>mot</span><span>word</span></div>");
+  });
+
+  test("some attributes are translated", () => {
+    const translations = {
+      word: "mot"
+    };
+    const translateFn = expr => translations[expr] || expr;
+    const qweb = new QWeb({ translateFn });
+    qweb.addTemplate(
+      "test",
+      `
+      <div>
+        <p label="word">word</p>
+        <p title="word">word</p>
+        <p placeholder="word">word</p>
+        <p alt="word">word</p>
+        <p something="word">word</p>
+      </div>`
+    );
+    expect(renderToString(qweb, "test")).toBe(
+      '<div><p label="mot">mot</p><p title="mot">mot</p><p placeholder="mot">mot</p><p alt="mot">mot</p><p something="word">mot</p></div>'
+    );
+  });
+});
+
+describe("t-key tests", () => {
+  test("t-key on t-foreach", async () => {
+    qweb.addTemplate(
+      "test",
+      `
+        <div>
+          <t t-foreach="things" t-as="thing" t-key="thing">
+            <span/>
+          </t>
+        </div>`
+    );
+
+    let vnode = qweb.render("test", { things: [1, 2] });
+    vnode = patch(document.createElement("div"), vnode);
+    let elm = vnode.elm as HTMLElement;
+
+    expect(elm.outerHTML).toBe("<div><span></span><span></span></div>");
+
+    const first = elm.querySelectorAll("span")[0];
+    const second = elm.querySelectorAll("span")[1];
+
+    patch(vnode, qweb.render("test", { things: [2, 1] }));
+
+    expect(elm.outerHTML).toBe("<div><span></span><span></span></div>");
+
+    expect(first).toBe(elm.querySelectorAll("span")[1]);
+    expect(second).toBe(elm.querySelectorAll("span")[0]);
+  });
+});

tests/router/__snapshots__/link.test.ts.snap

@@ -5,15 +5,13 @@ exports[`Link component can render simple cases 1`] = `
 ) {
     let utils = this.constructor.utils;
     let owner = context;
+    let sibling = null;
     var h = this.h;
     let _1 = utils.toObj({'router-link-active':context['isActive']});
     var _2 = context['href'];
     let c3 = [], p3 = {key:3,attrs:{href: _2},class:_1,on:{}};
     var vn3 = h('a', p3, c3);
-    if (!context['navigate']) {
-        throw new Error('Missing handler \\\\'' + 'navigate' + \`\\\\' when evaluating template '__template__1'\`)
-    }
-    extra.handlers['click' + 3] = extra.handlers['click' + 3] || context['navigate'].bind(owner);
+    extra.handlers['click' + 3] = extra.handlers['click' + 3] || function (e) {const fn = context['navigate'];if (fn) { fn.call(owner, e); } else { context.navigate; }};
     p3.on['click'] = extra.handlers['click' + 3];
     const slot4 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
     if (slot4) {

tests/router/__snapshots__/route_component.test.ts.snap

@@ -7,38 +7,39 @@ exports[`RouteComponent can render simple cases 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let owner = context;
+    let sibling = null;
     let result;
     var h = this.h;
     if (context['routeComponent']) {
+        const nodeKey1 = context['env'].router.currentRouteName;
         //COMPONENT
-        let key4 = 'key' + context['env'].router.currentRouteName;
-        let def2;
-        let templateId5 = key4;
-        let w3 = templateId5 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId5]] : false;
-        let vn6 = {};
-        result = vn6;
+        let templateId3 = \`__4__\` + nodeKey1;
+        let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
+        let vn5 = {};
+        result = vn5;
         let props3 = Object.assign({}, context['env'].router.currentParams);
         if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
-            if (utils.shallowEqual(props3, w3.__owl__.currentFiber.props)) {
-                def2 = w3.__owl__.currentFiber.promise;
-            } else {
-                w3.destroy();
-                w3 = false;
-            }
+            w3.destroy();
+            w3 = false;
         }
-        if (!w3) {
+        if (w3) {
+            w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
+            let pvnode = w3.__owl__.pvnode;
+            utils.defineProxy(vn5, pvnode);
+        } else {
             let componentKey3 = \`routeComponent\`;
             let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['routeComponent'];
             if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
             w3 = new W3(parent, props3);
-            parent.__owl__.cmap[templateId5] = w3.__owl__.id;
-            def2 = w3.__prepare(extra.fiber, undefined, undefined);
-            def2 = def2.then(vnode=>{if (w3.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: templateId5, hook: {insert(vn) {let nvn=w3.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});utils.defineProxy(vn6, pvnode);w3.__owl__.pvnode = pvnode;});
-        } else {
-            def2 = def2 || w3.__updateProps(props3, extra.fiber, undefined, undefined);
-            def2 = def2.then(()=>{if (w3.__owl__.isDestroyed) {return};let pvnode=w3.__owl__.pvnode;utils.defineProxy(vn6, pvnode);});
+            parent.__owl__.cmap[templateId3] = w3.__owl__.id;
+            let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
+            let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});
+            const fiber = w3.__owl__.currentFiber;
+            def2.then(function () {if (w3.__owl__.isDestroyed) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            utils.defineProxy(vn5, pvnode);
+            w3.__owl__.pvnode = pvnode;
         }
-        extra.promises.push(def2);
+        sibling = w3.__owl__.currentFiber || sibling;
     }
     return result;
 }"

tests/router/router.test.ts

@@ -52,6 +52,15 @@ describe("router miscellaneous", () => {
     expect(window.location.hash).toBe("#/users/5");
     expect(env.qweb.forceUpdate).toHaveBeenCalledTimes(2);
   });
+
+  test("navigate in hash mode preserve location", async () => {
+    router = new TestRouter(env, [{ name: "users", path: "/users/{{id}}" }], {mode: "hash"});
+    window.history.pushState({}, "title", window.location.origin + '/test.html');
+    expect(window.location.href).toBe("http://localhost/test.html");
+    await router.navigate({ to: "users", params: { id: 3 } });
+    expect(window.location.href).toBe("http://localhost/test.html#/users/3");
+  });
+
 });
 
 describe("routeToPath", () => {

tests/store_hooks.test.ts

@@ -51,8 +51,8 @@ describe("connecting a component to store", () => {
     const state = { a: 1, b: 2 };
     const actions = {
       doSomething({ state }) {
-          state.a = 2;
-          state.b = 3;
+        state.a = 2;
+        state.b = 3;
       }
     };
     const store = new Store({ state, actions });
@@ -63,8 +63,8 @@ describe("connecting a component to store", () => {
                 <span t-esc="a.value"/>
                 <span t-esc="b.value"/>
             </div>`;
-      a = useStore(state => ({value: state.a}));
-      b = useStore(state => ({value: state.b}));
+      a = useStore(state => ({ value: state.a }));
+      b = useStore(state => ({ value: state.b }));
     }
     App.prototype.__render = jest.fn(App.prototype.__render);
 
@@ -79,7 +79,7 @@ describe("connecting a component to store", () => {
     await nextTick();
     expect(fixture.innerHTML).toBe("<div><span>2</span><span>3</span></div>");
     expect(App.prototype.__render).toBeCalledTimes(2);
- });
+  });
 
   test("useStore: do not re-render if not changed", async () => {
     let nextId = 1;

tests/vdom.test.ts

@@ -185,20 +185,6 @@ describe("snabbdom", function() {
       expect(elm.tagName).toBe("DIV");
     });
 
-    test("has different tag and id", function() {
-      let elm: any = document.createElement("div");
-      vnode0.appendChild(elm);
-      const vnode1 = h("span#id");
-      elm = patch(elm, vnode1).elm;
-      expect(elm.tagName).toBe("SPAN");
-      expect(elm.id).toBe("id");
-    });
-
-    test("has id", function() {
-      elm = patch(vnode0, h("div", [h("div#unique")])).elm;
-      expect(elm.firstChild.id).toBe("unique");
-    });
-
     test("has correct namespace", function() {
       const SVGNamespace = "http://www.w3.org/2000/svg";
       const XHTMLNamespace = "http://www.w3.org/1999/xhtml";
@@ -218,20 +204,6 @@ describe("snabbdom", function() {
       expect(elm.firstChild.firstChild.namespaceURI).toBe(XHTMLNamespace);
     });
 
-    test("receives classes in selector", function() {
-      elm = patch(vnode0, h("div", [h("i.am.a.class")])).elm;
-      expect(elm.firstChild.classList.contains("am")).toBeTruthy();
-      expect(elm.firstChild.classList.contains("a")).toBeTruthy();
-      expect(elm.firstChild.classList.contains("class")).toBeTruthy();
-    });
-
-    test("receives classes in selector when namespaced", function() {
-      elm = patch(vnode0, h("svg", [h("g.am.a.class.too")])).elm;
-      expect(elm.firstChild.classList.contains("am")).toBeTruthy();
-      expect(elm.firstChild.classList.contains("a")).toBeTruthy();
-      expect(elm.firstChild.classList.contains("class")).toBeTruthy();
-    });
-
     test("can create elements with text content", function() {
       elm = patch(vnode0, h("div", ["I am a string"])).elm;
       expect(elm.innerHTML).toBe("I am a string");
@@ -268,26 +240,6 @@ describe("snabbdom", function() {
   });
 
   describe("patching an element", function() {
-    test("changes the elements classes", function() {
-      const vnode1 = h("i.i.am.horse");
-      const vnode2 = h("i.i.am");
-      patch(vnode0, vnode1);
-      elm = patch(vnode1, vnode2).elm;
-      expect(elm.classList.contains("i")).toBeTruthy();
-      expect(elm.classList.contains("am")).toBeTruthy();
-      expect(!elm.classList.contains("horse")).toBeTruthy();
-    });
-
-    test("removes missing classes", function() {
-      const vnode1 = h("i.i.am.horse");
-      const vnode2 = h("i.i.am");
-      patch(vnode0, vnode1);
-      elm = patch(vnode1, vnode2).elm;
-      expect(elm.classList.contains("i")).toBeTruthy();
-      expect(elm.classList.contains("am")).toBeTruthy();
-      expect(!elm.classList.contains("horse")).toBeTruthy();
-    });
-
     test("changes an elements props", function() {
       const vnode1 = h("a", { props: { src: "http://other/" } });
       const vnode2 = h("a", { props: { src: "http://localhost/" } });

tools/benchmarks/owl-0.24.0/app.js

@@ -0,0 +1,155 @@
+import { buildData, startMeasure, stopMeasure, formatNumber } from "../shared/utils.js";
+
+const { useState, useRef } = owl.hooks;
+//------------------------------------------------------------------------------
+// Likes Counter Widget
+//------------------------------------------------------------------------------
+class Counter extends owl.Component {
+  state = useState({ counter: 0 });
+
+  increment() {
+    this.state.counter++;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Message Widget
+//------------------------------------------------------------------------------
+class Message extends owl.Component {
+  static components = { Counter };
+
+  shouldUpdate(nextProps) {
+    return nextProps.message !== this.props.message;
+  }
+  removeMessage() {
+    this.trigger("remove-message", {
+      id: this.props.message.id
+    });
+  }
+}
+
+//------------------------------------------------------------------------------
+// Root Widget
+//------------------------------------------------------------------------------
+class App extends owl.Component {
+  static components = { Message };
+  state = useState({ messages: [], multipleFlag: false, clearAfterFlag: false });
+  logRef = useRef("log");
+
+  mounted() {
+    this.log(`Benchmarking Owl v${owl.__info__.version} (build date: ${owl.__info__.date})`);
+  }
+
+  benchmark(message, fn, callback) {
+    if (this.state.multipleFlag) {
+      const N = 20;
+      let n = N;
+      let total = 0;
+      let cb = info => {
+        let finalize = () => {
+          n--;
+          total += info.delta;
+          if (n === 0) {
+            const avg = total / N;
+            this.log(`Average: ${formatNumber(avg)}ms`, true);
+            if (callback) {
+              callback();
+            }
+          } else {
+            this._benchmark(message, fn, cb);
+          }
+        };
+
+        if (this.state.clearAfterFlag) {
+          this._benchmark(
+            "clear",
+            () => {
+              this.state.messages = [];
+            },
+            finalize,
+            false
+          );
+        } else {
+          finalize();
+        }
+      };
+      this._benchmark(message, fn, cb);
+    } else {
+      this._benchmark(message, fn, callback);
+    }
+  }
+
+  _benchmark(message, fn, cb, log = true) {
+    setTimeout(() => {
+      startMeasure(message);
+      fn();
+      stopMeasure(info => {
+        if (log) {
+          this.log(info.msg);
+        }
+        if (cb) {
+          cb(info);
+        }
+      });
+    }, 10);
+  }
+
+  addMessages(n) {
+    this.benchmark("add " + n, () => {
+      const newMessages = buildData(n);
+      this.state.messages.push.apply(this.state.messages, newMessages);
+    });
+  }
+
+  clear() {
+    this._benchmark("clear", () => {
+      this.state.messages = [];
+    });
+  }
+
+  updateSomeMessages() {
+    this.benchmark("update every 10th", () => {
+      const messages = this.state.messages;
+      for (let i = 0; i < messages.length; i += 10) {
+        const msg = Object.assign({}, messages[i]);
+        msg.author += "!!!";
+        messages[i] = msg;
+      }
+    });
+  }
+
+  removeMessage(event) {
+    this.benchmark("remove message", () => {
+      const index = this.state.messages.findIndex(m => m.id === event.detail.id);
+      this.state.messages.splice(index, 1);
+    });
+  }
+
+  log(str, isBold) {
+    const div = document.createElement("div");
+    if (isBold) {
+      div.classList.add("bold");
+    }
+    div.textContent = `> ${str}`;
+    this.logRef.el.appendChild(div);
+    this.logRef.el.scrollTop = this.logRef.el.scrollHeight;
+  }
+
+  clearLog() {
+    this.logRef.el.innerHTML = "";
+  }
+}
+
+//------------------------------------------------------------------------------
+// Application initialization
+//------------------------------------------------------------------------------
+async function start() {
+  const templates = await owl.utils.loadFile("templates.xml");
+  const env = {
+    qweb: new owl.QWeb(templates)
+  };
+  const app = new App(env);
+  app.mount(document.body);
+}
+
+start();

tools/benchmarks/owl-0.24.0/index.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>OWL v0.24.0 Benchmark</title>
+  <link href="../shared/main.css" rel="stylesheet"/>
+  <script src='../../owl.js'></script>
+</head>
+<body>
+  <script src='app.js' type="module"></script>
+</body>
+</html>

tools/benchmarks/owl-0.24.0/templates.xml

@@ -0,0 +1,50 @@
+<templates>
+  <div t-name="App" class="main">
+      <div class="left-thing">
+        <div class="title">Actions</div>
+        <div class="panel">
+          <button t-on-click="addMessages(100)">Add 100 messages</button>
+          <button t-on-click="addMessages(1000)">Add 1k messages</button>
+          <button t-on-click="addMessages(10000)">Add 10k messages</button>
+          <button t-on-click="addMessages(30000)">Add 30k messages</button>
+          <button t-on-click="updateSomeMessages">Update every 10th messages</button>
+          <button t-on-click="clear">Clear</button>
+        </div>
+        <div class="flags">
+            <div>
+                <input type="checkbox" id="multipleflag" t-model="state.multipleFlag"/>
+                <label for="multipleflag">Do it 20x</label>
+            </div>
+            <div>
+                <input type="checkbox" id="clearFlag" t-model="state.clearAfterFlag" />
+                <label for="clearFlag">Clear after</label>
+            </div>
+        </div>
+        <div class="info">Number of messages: <t t-esc="state.messages.length"/></div>
+        <hr/>
+        <div class="title">Log <span class="clear-log" t-on-click="clearLog">(clear)</span></div>
+        <div class="log">
+            <div class="log-content" t-ref="log"/>
+        </div>
+      </div>
+      <div class="right-thing">
+          <div class="content" t-on-remove-message="removeMessage">
+              <t t-foreach="state.messages" t-as="message">
+                  <Message t-key="message.id" message="message"/>
+              </t>
+          </div>
+      </div>
+  </div>
+
+  <div t-name="Message" class="message">
+    <span class="author"><t t-esc="props.message.author"/></span>
+    <span class="msg"><t t-esc="props.message.msg"/></span>
+    <button class="remove" t-on-click="removeMessage">Remove</button>
+    <Counter/>
+  </div>
+
+  <div t-name="Counter">
+    <button t-on-click="increment">Value: <t t-esc="state.counter"/></button>
+  </div>
+
+</templates>

tools/benchmarks/owl-master/app.js

@@ -144,9 +144,9 @@ class App extends owl.Component {
 // Application initialization
 //------------------------------------------------------------------------------
 async function start() {
-  const templates = await owl.utils.loadTemplates("templates.xml");
+  const templates = await owl.utils.loadFile("templates.xml");
   const env = {
-    qweb: new owl.QWeb(templates)
+    qweb: new owl.QWeb({ templates })
   };
   const app = new App(env);
   app.mount(document.body);

tools/benchmarks/shared/utils.js

@@ -44,15 +44,17 @@ export function startMeasure(descr) {
 export function stopMeasure(cb) {
   let last = lastMeasure;
   if (lastMeasure) {
-    window.setTimeout(function() {
-      lastMeasure = null;
-      const stop = performance.now();
-      const delta = stop - startTime;
-      const msg = `[${last}] took  ${formatNumber(delta)}ms`;
-      console.log(msg);
-      if (cb) {
-        cb({ msg, delta });
-      }
-    }, 0);
+      window.requestAnimationFrame(() => {
+        window.setTimeout(function() {
+        lastMeasure = null;
+        const stop = performance.now();
+        const delta = stop - startTime;
+        const msg = `[${last}] took  ${formatNumber(delta)}ms`;
+        console.log(msg);
+        if (cb) {
+            cb({ msg, delta });
+        }
+        }, 0);
+      });
   }
 }

tools/index.html

@@ -40,6 +40,7 @@
                 <li><a href="benchmarks/owl-0.17.0">OWL 0.17.0</a></li>
                 <li><a href="benchmarks/owl-0.18.0">OWL 0.18.0</a></li>
                 <li><a href="benchmarks/owl-0.21.0">OWL 0.21.0</a></li>
+                <li><a href="benchmarks/owl-0.24.0">OWL 0.24.0</a></li>
                 <li><a href="benchmarks/owl-master">OWL Master</a></li>
             </ul>
             <ul>

tools/playground/app.js

@@ -90,7 +90,7 @@ function makeCodeIframe(js, css, xml, errorHandler) {
     owlScript.addEventListener("load", () => {
       const script = doc.createElement("script");
       script.type = "text/javascript";
-      const content = `owl.__info__.mode = 'dev';\nwindow.TEMPLATES = \`${sanitizedXML}\`\n${js}`;
+      const content = `owl.__info__.mode = 'dev';\nwindow.TEMPLATES = \`${sanitizedXML}\`;\n${js}`;
       script.innerHTML = content;
       iframe.contentWindow.addEventListener("error", errorHandler);
       iframe.contentWindow.addEventListener("unhandledrejection", errorHandler);
@@ -127,7 +127,7 @@ async function makeApp(js, css, xml) {
   const JS = `
 async function loadTemplates() {
   try {
-    return owl.utils.loadTemplates('app.xml');
+    return owl.utils.loadFile('app.xml');
   } catch(e) {
     console.error(\`This app requires a static server.  If you have python installed, try 'python app.py'\`);
   }
@@ -429,11 +429,13 @@ App.components = { TabbedEditor };
 //------------------------------------------------------------------------------
 async function start() {
   document.title = `${document.title} (v${owl.__info__.version})`;
+  const commit = `https://github.com/odoo/owl/commit/${owl.__info__.hash}`;
+  console.info(`This application is using Owl built with the following commit:`, commit);
   const [templates] = await Promise.all([
-    owl.utils.loadTemplates("templates.xml"),
+    owl.utils.loadFile("templates.xml"),
     owl.utils.whenReady()
   ]);
-  const qweb = new owl.QWeb(templates);
+  const qweb = new owl.QWeb({ templates });
   const app = new App({ qweb });
   app.mount(document.body);
 }

tools/playground/samples.js

@@ -11,13 +11,13 @@ class Greeter extends Component {
 
 // Main root component
 class App extends Component {
-    static components = { Greeter };
     state = useState({ name: 'World'});
 }
+App.components = { Greeter };
 
 // Application setup
 // Note that the xml templates are injected into the global TEMPLATES variable.
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({ qweb });
 app.mount(document.body);
 `;
@@ -58,7 +58,6 @@ class Counter extends Component {
 
 class App extends Component {
     state = useState({ flag: false, componentFlag: false, numbers: [] });
-    static components = { Counter };
 
     toggle(key) {
         this.state[key] = !this.state[key];
@@ -68,10 +67,10 @@ class App extends Component {
         const n = this.state.numbers.length + 1;
         this.state.numbers.push(n);
     }
-
 }
+App.components = { Counter };
 
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({qweb});
 app.mount(document.body);
 `;
@@ -217,7 +216,6 @@ class DemoComponent extends Component {
 }
 
 class App extends Component {
-    static components = { DemoComponent };
     state = useState({ n: 0, flag: true });
 
     increment() {
@@ -228,8 +226,9 @@ class App extends Component {
         this.state.flag = !this.state.flag;
     }
 }
+App.components = { DemoComponent };
 
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({ qweb });
 app.mount(document.body);
 `;
@@ -299,7 +298,7 @@ class App extends owl.Component {
 }
 
 // Application setup
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({ qweb });
 app.mount(document.body);
 `;
@@ -332,20 +331,18 @@ class ToolbarButton extends Component {
     }
 }
 
-class Toolbar extends Component {
-    static components = { ToolbarButton };
-}
+class Toolbar extends Component {}
+Toolbar.components = { ToolbarButton };
 
 // Main root component
 class App extends Component {
-    static components = { Toolbar };
-
     toggleTheme() {
         const { background, foreground } = this.env.themeContext.state;
         this.env.themeContext.state.background = foreground;
         this.env.themeContext.state.foreground = background;
     }
 }
+App.components = { Toolbar };
 
 // Application setup
 const themeContext = new Context({
@@ -353,7 +350,7 @@ const themeContext = new Context({
    foreground: '#fff',
 });
 const env = {
-    qweb: new owl.QWeb(TEMPLATES),
+    qweb: new owl.QWeb({ templates: TEMPLATES}),
     themeContext: themeContext,
 };
 const app = new App(env);
@@ -469,10 +466,6 @@ class TodoItem extends Component {
         useAutofocus("input");
     }
 
-    editTodo() {
-        this.state.isEditing = true;
-    }
-
     handleKeyup(ev) {
         if (ev.keyCode === ENTER_KEY) {
             this.updateTitle(ev.target.value);
@@ -497,7 +490,6 @@ class TodoItem extends Component {
 // TodoApp
 //------------------------------------------------------------------------------
 class TodoApp extends Component {
-    static components = { TodoItem };
     state = useState({ filter: "all" });
     todos = useStore(state => state.todos);
     dispatch = useDispatch();
@@ -537,6 +529,7 @@ class TodoApp extends Component {
         this.state.filter = filter;
     }
 }
+TodoApp.components = { TodoItem };
 
 //------------------------------------------------------------------------------
 // App Initialization
@@ -555,7 +548,7 @@ function makeEnv() {
     const state = loadState();
     const store = new owl.Store({ state, actions });
     store.on("update", null, () => saveState(store.state));
-    const qweb = new owl.QWeb(TEMPLATES);
+    const qweb = new owl.QWeb({ templates: TEMPLATES});
     return { qweb, store };
 }
 
@@ -606,7 +599,7 @@ const TODO_APP_STORE_XML = `<templates>
   <li t-name="TodoItem" class="todo" t-att-class="{completed: props.completed, editing: state.isEditing}">
     <div class="view">
       <input class="toggle" type="checkbox" t-on-change="dispatch('toggleTodo', props.id)" t-att-checked="props.completed"/>
-      <label t-on-dblclick="editTodo">
+      <label t-on-dblclick="state.isEditing = true">
         <t t-esc="props.title"/>
       </label>
       <button class="destroy" t-on-click="dispatch('removeTodo', props.id)"></button>
@@ -1014,23 +1007,20 @@ class Navbar extends owl.Component {}
 
 class MobileSearchView extends owl.Component {}
 
-class ControlPanel extends owl.Component {
-    static components = { MobileSearchView };
-}
+class ControlPanel extends owl.Component {}
+ControlPanel.components = { MobileSearchView };
 
 class AdvancedComponent extends owl.Component {}
 
-class FormView extends owl.Component {
-    static components = { AdvancedComponent };
-}
+class FormView extends owl.Component {}
+FormView.components = { AdvancedComponent };
 
 class Chatter extends owl.Component {
     messages = Array.from(Array(100).keys());
 }
 
-class App extends owl.Component {
-    static components = { Navbar, ControlPanel, FormView, Chatter };
-}
+class App extends owl.Component {}
+App.components = { Navbar, ControlPanel, FormView, Chatter };
 
 //------------------------------------------------------------------------------
 // Responsive plugin
@@ -1051,7 +1041,7 @@ function setupResponsivePlugin(env) {
 // Application Startup
 //------------------------------------------------------------------------------
 const env = {
-    qweb: new owl.QWeb(TEMPLATES),
+    qweb: new owl.QWeb({ templates: TEMPLATES}),
 };
 setupResponsivePlugin(env);
 
@@ -1188,16 +1178,16 @@ class Counter extends Component {
 
 // Main root component
 class App extends Component {
-    static components = {Card, Counter};
     state = useState({a: 1, b: 3});
 
     inc(key, delta) {
         this.state[key] += delta;
     }
 }
+App.components = {Card, Counter};
 
 // Application setup
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({ qweb });
 app.mount(document.body);`;
 
@@ -1283,9 +1273,10 @@ const ASYNC_COMPONENTS = `// This example will not work if your browser does not
 
 // In this example, we have 2 sub components, one of them being async (slow).
 // However, we don't want renderings of the other sub component to be delayed
-// because of the slow component. We use the 't-asyncroot' directive for this
+// because of the slow component. We use the AsyncRoot component for this
 // purpose. Try removing it to see the difference.
 const { Component, useState } = owl;
+const { AsyncRoot } = owl.misc;
 
 class SlowComponent extends Component {
     willUpdateProps() {
@@ -1298,7 +1289,6 @@ class SlowComponent extends Component {
 class NotificationList extends Component {}
 
 class App extends Component {
-    static components = {SlowComponent, NotificationList};
     state = useState({ value: 0, notifs: [] });
 
     increment() {
@@ -1311,8 +1301,9 @@ class App extends Component {
         }, 3000);
     }
 }
+App.components = {SlowComponent, NotificationList};
 
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const app = new App({ qweb });
 app.mount(document.body);
 `;
@@ -1321,9 +1312,10 @@ const ASYNC_COMPONENTS_XML = `<templates>
   <div t-name="App" class="app">
     <button t-on-click="increment">Increment</button>
     <SlowComponent value="state.value"/>
-    <NotificationList t-asyncroot="1" notifications="state.notifs"/>
+    <AsyncRoot>
+      <NotificationList notifications="state.notifs"/>
+    </AsyncRoot>
   </div>
-
   <div t-name="SlowComponent" class="value" >
     Current value: <t t-esc="props.value"/>
   </div>
@@ -1381,7 +1373,7 @@ class Form extends Component {
 }
 
 // Application setup
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const form = new Form({ qweb });
 form.mount(document.body);
 `;
@@ -1492,7 +1484,6 @@ class Window extends Component {
 }
 
 class WindowManager extends Component {
-  static components = { Window };
   windows = [];
   nextId = 1;
   currentZindex = 1;
@@ -1538,17 +1529,18 @@ class WindowManager extends Component {
     ev.target.style["z-index"] = w.zindex;
   }
 }
+WindowManager.components = { Window };
 
 class App extends Component {
-  static components = { WindowManager };
   wmRef = useRef("wm");
 
   addWindow(name) {
     this.wmRef.comp.addWindow(name);
   }
 }
+App.components = { WindowManager };
 
-const qweb = new owl.QWeb(TEMPLATES);
+const qweb = new owl.QWeb({ templates: TEMPLATES});
 const windows = [
   {
     name: "Hello",