[REL] v1.0.0

Finally!!

README.md

@@ -102,10 +102,16 @@ Submit a PR!
 
 ## Installing/Building
 
+Owl can be installed with the following command:
+
+```
+npm install @odoo/owl
+```
+
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-1.0.0-beta2.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.js)
-- [owl-1.0.0-beta2.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.min.js)
+- [owl-1.0.0.js](https://github.com/odoo/owl/releases/download/v1.0.0/owl.js)
+- [owl-1.0.0.min.js](https://github.com/odoo/owl/releases/download/v1.0.0/owl.min.js)
 
 Some npm scripts are available:
 

doc/readme.md

@@ -56,15 +56,15 @@ useState                                    Link
 config                                      RouteComponent
     mode                                    Router
 core                                    tags
-    EventBus                                xml
-    Observer                            utils
-hooks                                       debounce
-    onWillStart                             escape
-    onMounted                               loadJS
-    onWillUpdateProps                       loadFile
-    onWillPatch                             shallowEqual
-    onPatched                               whenReady
-    onWillUnmount
+    EventBus                                css
+    Observer                                xml
+hooks                                   utils
+    onWillStart                             debounce
+    onMounted                               escape
+    onWillUpdateProps                       loadJS
+    onWillPatch                             loadFile
+    onPatched                               shallowEqual
+    onWillUnmount                           whenReady
     useContext
     useState
     useRef

doc/reference/component.md

@@ -225,6 +225,10 @@ to be called in the constructor.
   }
   ```
 
+- **`style`** (string, optional): it should be the return value of the [`css` tag](tags.md#css-tag),
+  which is used to inject stylesheet whenever the component is visible on the
+  screen.
+
 There is another static property defined on the `Component` class: `current`.
 This property is set to the currently being defined component (in the constructor).
 This is the way [hooks](hooks.md) are able to get a reference to the target
@@ -421,7 +425,7 @@ likely via a change in its state/props or environment).
 
 This method is not called on the initial render. It is useful to interact
 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
+component was patched. Note that this hook will not be called if the component is
 not in the DOM.
 
 Updating the component state in this hook is possible, but not encouraged.

doc/reference/concurrency_model.md

@@ -23,7 +23,7 @@ a rendering that is no longer relevant, restart it, reuse it in some cases.
 But even though using concurrency is quite simple (and is the default behaviour),
 asynchrony is difficult, because it introduces an additional dimension that
 vastly increase the complexity of an application. This section will explain
-how Owl manages this complexity, how concuurent rendering works in a general way.
+how Owl manages this complexity, how concurrent rendering works in a general way.
 
 ## Rendering Components
 
@@ -120,7 +120,7 @@ Here is what Owl will do:
      1. hook `willUpdateProps` is called on `D` (async)
      2. template `D` is rerendered
    - component `F` is created:
-     1. hook `willStart` is called on `E` (async)
+     1. hook `willStart` is called on `F` (async)
      2. template `F` is rendered
 
 3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,

doc/reference/environment.md

@@ -40,8 +40,8 @@ all templates.
 Whenever a root component `App` is mounted, Owl will setup a valid environment by
 following the next steps:
 
-- take the `env` object defined on `App.env` (if no `env` was explicitely setup,
-  this will be return the empty `env` object defined on `Component`)
+- take the `env` object defined on `App.env` (if no `env` was explicitly setup,
+  this will return the empty `env` object defined on `Component`)
 - if `env.qweb` is not set, then Owl will create a `QWeb` instance.
 
 The correct way to customize an environment is to simply set it up on the root

doc/reference/hooks.md

@@ -17,6 +17,7 @@
   - [`useContext`](#usecontext)
   - [`useRef`](#useref)
   - [`useSubEnv`](#usesubenv)
+  - [`useExternalListener`](#useexternallistener)
   - [`useStore`](#usestore)
   - [`useDispatch`](#usedispatch)
   - [`useGetters`](#usegetters)
@@ -354,6 +355,17 @@ will be added to the parent environment. Note that it will extend, not replace
 the parent environment. And of course, the parent environment will not be
 affected.
 
+### `useExternalListener`
+
+The `useExternalListener` hook helps solve a very common problem: adding and removing
+a listener on some target whenever a component is mounted/unmounted. For example,
+a dropdown menu (or its parent) may need to listen to a `click` event on `window`
+to be closed:
+
+```js
+useExternalListener(window, "click", this.closeMenu);
+```
+
 ### `useStore`
 
 The `useStore` hook is the entry point for a component to connect to the store.

doc/reference/tags.md

@@ -4,16 +4,19 @@
 
 - [Overview](#overview)
 - [`xml` tag](#xml-tag)
+- [`css` tag](#css-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](../tooling.md#single-file-component).
+Tags are very small helpers intended to make it easy to write inline templates
+or styles. There are currently two tags: `css` and `xml`. With these functions,
+it is possible to write [single file components](../tooling.md#single-file-component).
 
 ## XML tag
 
-Without tags, creating a standalone component would look like this:
+The `xml` tag is certainly the most useful tag. It is used to define an inline
+QWeb template for a component. Without tags, creating a standalone component
+would look like this:
 
 ```js
 import { Component } from 'owl'
@@ -52,3 +55,130 @@ class MyComponent extends Component {
     ...
 }
 ```
+
+## CSS tag
+
+The CSS tag is useful to define a css stylesheet in the javascript file:
+
+```js
+class MyComponent extends Component {
+    static template = xml`
+        <div class="my-component">some template</div>
+    `;
+    static css`
+      .my-component {
+          color: red;
+      }
+    `;
+}
+```
+
+The `css` tag registers internally the css information. Then, whenever the first
+instance of the component is created, will add a `<style>` tag to the document
+`<head>`.
+
+Note that to make it more useful, like other css preprocessors, the `css` tag
+accepts a small extension of the css specification: css scopes can be nested,
+and the rules will then be expanded by the `css` helper:
+
+```scss
+.my-component {
+  display: block;
+  .sub-component h {
+    color: red;
+  }
+}
+```
+
+will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component .sub-component h {
+  color: red;
+}
+```
+
+This extension brings another useful feature: the `&` selector which refers to
+the parent selector. For example, we want our component to be red when hovered.
+We would like to write something like:
+
+```scss
+.my-component {
+  display: block;
+  :hover {
+    color: red;
+  }
+}
+```
+
+but it will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component :hover {
+  color: red;
+}
+```
+
+The `&` selector can be used to solve this problem:
+
+```scss
+.my-component {
+  display: block;
+  &:hover {
+    color: red;
+  }
+}
+```
+
+will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component:hover {
+  color: red;
+}
+```
+
+Now, there is no additional processing done by the `css` tag. However, since it
+is done in javascript at runtime, we actually have more power. For example:
+
+1. sharing values between javascript and css:
+
+```js
+import { theme } from "./theme";
+
+class MyComponent extends Component {
+  static template = xml`<div class="my-component">...</div>`;
+  static style = css`
+    .my-component {
+      color: ${theme.MAIN_COLOR};
+      background-color: ${theme.SECONDARY_color};
+    }
+  `;
+}
+```
+
+2. scoping rules to the current component:
+
+```js
+import { generateUUID } from "./utils";
+
+const uuid = generateUUID();
+
+class MyComponent extends Component {
+  static template = xml`<div data-o-${uuid}="">...</div>`;
+  static style = css`
+        [data-o-${uuid}] {
+            color: red;
+        }
+    `;
+}
+```

doc/tooling.md

@@ -43,32 +43,43 @@ useful to compare various performance metrics on some tasks.
 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_engine.md).
+To do so, Owl has two small helpers that make it easy to define a
+template or a stylesheet inside a javascript (or typescript) file: the
+[`xml`](reference/tags.md#xml-tag) and [`css`](reference/tags.md#css-tag)
+helper.
 
-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.
+This means that the template, the style and the javascript code can be defined in
+the same file. For example:
 
 ```js
 const { Component } = owl;
-const { xml } = owl.tags;
+const { xml, css } = owl.tags;
 
 // -----------------------------------------------------------------------------
 // TEMPLATE
 // -----------------------------------------------------------------------------
 const TEMPLATE = xml/* xml */ `
-	<div class="main two-columns">
+	<div class="main">
 		<Sidebar/>
 		<Content />
 	</div>`;
 
+// -----------------------------------------------------------------------------
+// STYLE
+// -----------------------------------------------------------------------------
+const STYLE = css/* css */ `
+  .main {
+    display: grid;
+    grid-template-columns: 200px auto;
+  }
+`;
+
 // -----------------------------------------------------------------------------
 // CODE
 // -----------------------------------------------------------------------------
-class MyComponent extends Component {
+class Main extends Component {
   static template = TEMPLATE;
+  static style = STYLE;
   static components = { Sidebar, Content };
 
   // rest of component...
@@ -91,7 +102,7 @@ logging useful information is extremely valuable. There is a [javascript file](.
 Once it is executed, it will log a lot of information on each component main hooks. The following code is a minified version to make it easier to copy/paste:
 
 ```
-function debugOwl(t,n){let e,o="[OWL_DEBUG]";function s(t){let n=JSON.stringify(t||{});return n.length>200&&(n=n.slice(0,200)+"..."),n}if(Object.defineProperty(t.Component,"current",{get:()=>e,set(i){e=i;const r=i.constructor.name;if(n.componentBlackList&&n.componentBlackList.test(r))return;if(n.componentWhiteList&&!n.componentWhiteList.test(r))return;let l;Object.defineProperty(e,"__owl__",{get:()=>l,set(e){!function(e,i,r){let l=`${i}<id=${r}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!n.methodBlackList||!n.methodBlackList.includes(t))&&!(n.methodWhiteList&&!n.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${s(e.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${s(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=e.__render.bind(e);e.__render=function(...t){c("rendering template"),d(...t)};const h=e.render.bind(e);e.render=function(...t){const n=e.__owl__;let o="render";return n.isMounted||n.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=e.mount.bind(e);e.mount=function(...t){return c("mount"),p(...t)}}(i,r,(l=e).id)}})}}),n.logScheduler){let n=t.Component.scheduler.start,e=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),n.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),e.call(this)}}if(n.logStore){let n=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...e){return console.log(`${o} store: action '${t}' dispatched. Payload: '${s(e)}'`),n.call(this,t,...e)}}}
+function debugOwl(t,e){let n,o="[OWL_DEBUG]";function r(t){let e;try{e=JSON.stringify(t||{})}catch(t){e="<JSON error>"}return e.length>200&&(e=e.slice(0,200)+"..."),e}if(Object.defineProperty(t.Component,"current",{get:()=>n,set(s){n=s;const i=s.constructor.name;if(e.componentBlackList&&e.componentBlackList.test(i))return;if(e.componentWhiteList&&!e.componentWhiteList.test(i))return;let l;Object.defineProperty(n,"__owl__",{get:()=>l,set(n){!function(n,s,i){let l=`${s}<id=${i}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!e.methodBlackList||!e.methodBlackList.includes(t))&&!(e.methodWhiteList&&!e.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${r(n.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${r(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=n.__render.bind(n);n.__render=function(...t){c("rendering template"),d(...t)};const h=n.render.bind(n);n.render=function(...t){const e=n.__owl__;let o="render";return e.isMounted||e.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=n.mount.bind(n);n.mount=function(...t){return c("mount"),p(...t)}}(s,i,(l=n).id)}})}}),e.logScheduler){let e=t.Component.scheduler.start,n=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),e.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),n.call(this)}}if(e.logStore){let e=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...n){return console.log(`${o} store: action '${t}' dispatched. Payload: '${r(n)}'`),e.call(this,t,...n)}}}
 debugOwl(owl, {
   // componentBlackList: /App/,  // regexp
   // componentWhiteList: /SomeComponent/, // regexp

package.json

@@ -1,8 +1,11 @@
 {
-  "name": "owl-framework",
-  "version": "1.0.0-beta2",
+  "name": "@odoo/owl",
+  "version": "1.0.0",
   "description": "Odoo Web Library (OWL)",
-  "main": "src/index.ts",
+  "main": "dist/owl.js",
+  "types": "dist/types/index.d.ts",
+  "prepublish": "npm run buildcommonjs",
+  "files": ["dist/types/", "dist/owl.js"],
   "engines": {
     "node": ">=10.15.3"
   },

roadmap.md

@@ -1,7 +1,7 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.0.0-beta2
-- Status: mostly stable
+- Current version: 1.0.0
+- Status: stable
 
 This roadmap is only an attempt at predicting Owl's future.  Everything may
 change!

src/component/component.ts

@@ -6,6 +6,7 @@ import "./directive";
 import { Fiber } from "./fiber";
 import "./props_validation";
 import { Scheduler, scheduler } from "./scheduler";
+import { activateSheet } from "./styles";
 
 /**
  * Owl Component System
@@ -199,6 +200,9 @@ export class Component<T extends Env, Props extends {}> {
       refs: null,
       scope: null
     };
+    if (constr.style) {
+      this.__applyStyles(constr);
+    }
   }
 
   /**
@@ -580,6 +584,20 @@ export class Component<T extends Env, Props extends {}> {
     return fiber;
   }
 
+  /**
+   * Apply the stylesheets defined by the component. Note that we need to make
+   * sure all inherited stylesheets are applied as well.  We then delete the
+   * `style` key from the constructor to make sure we do not apply it again.
+   */
+  private __applyStyles(constr) {
+    while (constr && constr.style) {
+      if (constr.hasOwnProperty("style")) {
+        activateSheet(constr.style, constr.name);
+        delete constr.style;
+      }
+      constr = constr.__proto__;
+    }
+  }
   __getTemplate(qweb: QWeb): string {
     let p = (<any>this).constructor;
     if (!p.hasOwnProperty("_template")) {

src/component/directive.ts

@@ -211,7 +211,7 @@ QWeb.addDirective({
       } else if (!name.startsWith("t-")) {
         if (name !== "class" && name !== "style") {
           // this is a prop!
-          props[name] = ctx.formatExpression(value);
+          props[name] = ctx.formatExpression(value) || "undefined";
         }
       }
     }

src/component/styles.ts

@@ -0,0 +1,70 @@
+/**
+ * Owl Style System
+ *
+ * This files contains the Owl code related to processing (extended) css strings
+ * and creating/adding <style> tags to the document head.
+ */
+
+export const STYLESHEETS: { [id: string]: HTMLStyleElement } = {};
+
+export function processSheet(str: string): string {
+  const tokens = str.split(/(\{|\}|;)/).map(s => s.trim());
+  const selectorStack: string[][] = [];
+  const parts: string[] = [];
+  let rules: string[] = [];
+  function generateSelector(stackIndex: number, parentSelector?: string) {
+    const parts: string[] = [];
+    for (const selector of selectorStack[stackIndex]) {
+      let part = (parentSelector && parentSelector + " " + selector) || selector;
+      if (part.includes("&")) {
+        part = selector.replace(/&/g, parentSelector || "");
+      }
+      if (stackIndex < selectorStack.length - 1) {
+        part = generateSelector(stackIndex + 1, part);
+      }
+      parts.push(part);
+    }
+    return parts.join(", ");
+  }
+  function generateRules() {
+    if (rules.length) {
+      parts.push(generateSelector(0) + " {");
+      parts.push(...rules);
+      parts.push("}");
+      rules = [];
+    }
+  }
+  while (tokens.length) {
+    let token = tokens.shift()!;
+    if (token === "}") {
+      generateRules();
+      selectorStack.pop();
+    } else {
+      if (tokens[0] === "{") {
+        generateRules();
+        selectorStack.push(token.split(/\s*,\s*/));
+        tokens.shift();
+      }
+      if (tokens[0] === ";") {
+        rules.push("  " + token + ";");
+      }
+    }
+  }
+  return parts.join("\n");
+}
+export function registerSheet(id: string, css: string) {
+  const sheet = document.createElement("style");
+  sheet.innerHTML = processSheet(css);
+  STYLESHEETS[id] = sheet;
+}
+
+export function activateSheet(id, name) {
+  const sheet = STYLESHEETS[id];
+  if (!sheet) {
+    throw new Error(
+      `Invalid css stylesheet for component '${name}'. Did you forget to use the 'css' tag helper?`
+    );
+  }
+  sheet.setAttribute("component", name);
+  document.head.appendChild(sheet);
+}

src/hooks.ts

@@ -131,3 +131,27 @@ export function useSubEnv(nextEnv) {
   const component = Component.current!;
   component.env = Object.assign(Object.create(component.env), nextEnv);
 }
+
+// -----------------------------------------------------------------------------
+// useExternalListener
+// -----------------------------------------------------------------------------
+
+/**
+ * When a component needs to listen to DOM Events on element(s) that are not
+ * part of his hierarchy, we can use the `useExternalListener` hook.
+ * It will correctly add and remove the event listener, whenever the
+ * component is mounted and unmounted.
+ *
+ * Example:
+ *  a menu needs to listen to the click on window to be closed automatically
+ *
+ * Usage:
+ *  in the constructor of the OWL component that needs to be notified,
+ *  `useExternalListener(window, 'click', this._doSomething);`
+ * */
+export function useExternalListener(target: HTMLElement, eventName: string, handler, eventParams?) {
+  const boundHandler = handler.bind(Component.current);
+
+  onMounted(() => target.addEventListener(eventName, boundHandler, eventParams));
+  onWillUnmount(() => target.removeEventListener(eventName, boundHandler, eventParams));
+}

src/qweb/base_directives.ts

@@ -1,6 +1,7 @@
 import { CompilationContext } from "./compilation_context";
 import { QWeb } from "./qweb";
 import { htmlToVDOM } from "../vdom/html_to_vdom";
+import { QWebVar } from "./expression_parser";
 
 /**
  * Owl QWeb Directives
@@ -119,7 +120,7 @@ QWeb.addDirective({
     ctx.rootContext.shouldDefineScope = true;
     const variable = node.getAttribute("t-set")!;
     let value = node.getAttribute("t-value")!;
-    ctx.variables[variable] = ctx.variables[variable] || {};
+    ctx.variables[variable] = ctx.variables[variable] || ({} as QWebVar);
     let qwebvar = ctx.variables[variable];
     const hasBody = node.hasChildNodes();
 
@@ -127,7 +128,12 @@ QWeb.addDirective({
     qwebvar.expr = `scope.${variable}`;
     if (value) {
       const formattedValue = ctx.formatExpression(value);
-      ctx.addLine(`${qwebvar.expr} = ${formattedValue};`);
+      let scopeExpr = `scope`;
+      if (ctx.protectedScopeNumber) {
+        ctx.rootContext.shouldDefineUtils = true;
+        scopeExpr = `utils.getScope(scope, '${variable}')`;
+      }
+      ctx.addLine(`${scopeExpr}.${variable} = ${formattedValue};`);
       qwebvar.value = formattedValue;
     }
 
@@ -229,7 +235,7 @@ QWeb.addDirective({
     // ------------------------------------------------
     if (!qweb.subTemplates[subTemplate]) {
       qweb.subTemplates[subTemplate] = true;
-      const subTemplateFn = qweb._compile(subTemplate, nodeTemplate.elem, ctx);
+      const subTemplateFn = qweb._compile(subTemplate, nodeTemplate.elem, ctx, true);
       qweb.subTemplates[subTemplate] = subTemplateFn;
     }
 
@@ -264,17 +270,16 @@ QWeb.addDirective({
     // ------------------------------------------------
     const callingScope = hasBody ? "scope" : "Object.assign(Object.create(context), scope)";
     const parentComponent = `utils.getComponent(context)`;
+    const key = ctx.generateTemplateKey();
+    const parentNode = ctx.parentNode ? `c${ctx.parentNode}` : "result";
+    const extra = `Object.assign({}, extra, {parentNode: ${parentNode}, parent: ${parentComponent}, key: ${key}})`;
     if (ctx.parentNode) {
-      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: c${ctx.parentNode}, parent: ${parentComponent}}));`
-      );
+      ctx.addLine(`this.subTemplates['${subTemplate}'].call(this, ${callingScope}, ${extra});`);
     } else {
       // this is a t-call with no parentnode, we need to extract the result
       ctx.rootContext.shouldDefineResult = true;
       ctx.addLine(`result = []`);
-      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: result, parent: ${parentComponent}}));`
-      );
+      ctx.addLine(`this.subTemplates['${subTemplate}'].call(this, ${callingScope}, ${extra});`);
       ctx.addLine(`result = result[0]`);
     }
 
@@ -313,7 +318,7 @@ QWeb.addDirective({
     ctx.addLine(`_${valuesID} = Object.values(_${arrayID});`);
     ctx.closeIf();
     ctx.addLine(`let _length${keysID} = _${keysID}.length;`);
-    let varsID = ctx.startProtectScope();
+    let varsID = ctx.startProtectScope(true);
     const loopVar = `i${ctx.loopNumber}`;
     ctx.addLine(`for (let ${loopVar} = 0; ${loopVar} < _length${keysID}; ${loopVar}++) {`);
     ctx.indent();
@@ -334,6 +339,13 @@ QWeb.addDirective({
         `Directive t-foreach should always be used with a t-key! (in template: '${ctx.templateName}')`
       );
     }
+    if (nodeCopy.hasAttribute("t-key")) {
+      const expr = ctx.formatExpression(nodeCopy.getAttribute("t-key")!);
+      ctx.addLine(`let key${ctx.loopNumber} = ${expr};`);
+      nodeCopy.removeAttribute("t-key");
+    } else {
+      ctx.addLine(`let key${ctx.loopNumber} = i${ctx.loopNumber};`);
+    }
 
     nodeCopy.removeAttribute("t-foreach");
     qweb._compileNode(nodeCopy, ctx);

src/qweb/compilation_context.ts

@@ -1,4 +1,4 @@
-import { compileExpr, QWebVar } from "./expression_parser";
+import { compileExpr, compileExprToArray, QWebVar } from "./expression_parser";
 
 export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 //------------------------------------------------------------------------------
@@ -17,6 +17,7 @@ export class CompilationContext {
   rootContext: CompilationContext;
   shouldDefineParent: boolean = false;
   shouldDefineScope: boolean = false;
+  protectedScopeNumber: number = 0;
   shouldDefineQWeb: boolean = false;
   shouldDefineUtils: boolean = false;
   shouldDefineRefs: boolean = false;
@@ -26,7 +27,8 @@ export class CompilationContext {
   templateName: string;
   allowMultipleRoots: boolean = false;
   hasParentWidget: boolean = false;
-  currentKey: string = "";
+  hasKey0: boolean = false;
+  keyStack: boolean[] = [];
 
   constructor(name?: string) {
     this.rootContext = this;
@@ -48,20 +50,15 @@ export class CompilationContext {
    */
   generateTemplateKey(prefix: string = ""): string {
     const id = this.generateID();
-    if (this.loopNumber === 0 && !this.currentKey) {
+    if (this.loopNumber === 0 && !this.hasKey0) {
       return `'${prefix}__${id}__'`;
     }
-    let locationExpr = `\`${prefix}__${id}__`;
-    for (let i = 0; i < this.loopNumber - 1; i++) {
-      locationExpr += `\${i${i + 1}}__`;
-    }
-    if (this.currentKey) {
-      const k = this.currentKey;
-      this.addLine(`let k${id} = ${locationExpr}\` + ${k};`);
-    } else {
-      locationExpr += this.loopNumber ? `\${i${this.loopNumber}}__\`` : "`";
-      this.addLine(`let k${id} = ${locationExpr};`);
+    let key = `\`${prefix}__${id}__`;
+    let start = this.hasKey0 ? 0 : 1;
+    for (let i = start; i < this.loopNumber + 1; i++) {
+      key += `\${key${i}}__`;
     }
+    this.addLine(`let k${id} = ${key}\`;`);
     return `k${id}`;
   }
 
@@ -116,11 +113,11 @@ export class CompilationContext {
   }
 
   indent() {
-    this.indentLevel++;
+    this.rootContext.indentLevel++;
   }
 
   dedent() {
-    this.indentLevel--;
+    this.rootContext.indentLevel--;
   }
 
   addLine(line: string): number {
@@ -159,6 +156,24 @@ export class CompilationContext {
     this.rootContext.shouldDefineScope = true;
     return compileExpr(expr, this.variables);
   }
+  captureExpression(expr: string): string {
+    this.rootContext.shouldDefineScope = true;
+    const argId = this.generateID();
+    const tokens = compileExprToArray(expr, this.variables);
+    const done = new Set();
+    return tokens
+      .map(tok => {
+        if (tok.varName) {
+          if (!done.has(tok.varName)) {
+            done.add(tok.varName);
+            this.addLine(`const ${tok.varName}_${argId} = ${tok.value};`);
+          }
+          tok.value = `${tok.varName}_${argId}`;
+        }
+        return tok.value;
+      })
+      .join("");
+  }
 
   /**
    * Perform string interpolation on the given string. Note that if the whole
@@ -177,14 +192,19 @@ export class CompilationContext {
     let r = s.replace(/\{\{.*?\}\}/g, s => "${" + this.formatExpression(s.slice(2, -2)) + "}");
     return "`" + r + "`";
   }
-  startProtectScope(): number {
+  startProtectScope(codeBlock?: boolean): number {
     const protectID = this.generateID();
+    this.rootContext.protectedScopeNumber++;
     this.rootContext.shouldDefineScope = true;
+    const scopeExpr = codeBlock
+      ? `Object.create(scope);`
+      : `Object.assign(Object.create(context), scope);`;
     this.addLine(`let _origScope${protectID} = scope;`);
-    this.addLine(`scope = Object.assign(Object.create(context), scope);`);
+    this.addLine(`scope = ${scopeExpr}`);
     return protectID;
   }
   stopProtectScope(protectID: number) {
+    this.rootContext.protectedScopeNumber--;
     this.addLine(`scope = _origScope${protectID};`);
   }
 }

src/qweb/expression_parser.ts

@@ -66,6 +66,7 @@ interface Token {
   value: string;
   originalValue?: string;
   size?: number;
+  varName?: string;
 }
 
 const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
@@ -81,7 +82,7 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
 
 // note that the space after typeof is relevant. It makes sure that the formatted
 // expression has a space after typeof
-const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;".split(",");
+const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ".split(",");
 
 type Tokenizer = (expr: string) => Token | false;
 
@@ -234,7 +235,7 @@ export function tokenize(expr: string): Token[] {
  * the arrow operator, then we add the current (or some previous tokens) token to
  * the list of variables so it does not get replaced by a lookup in the context
  */
-export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
+export function compileExprToArray(expr: string, scope: { [key: string]: QWebVar }): Token[] {
   scope = Object.create(scope);
   const tokens = tokenize(expr);
   for (let i = 0; i < tokens.length; i++) {
@@ -269,6 +270,7 @@ export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): st
     }
 
     if (isVar) {
+      token.varName = token.value;
       if (token.value in scope && "id" in scope[token.value]) {
         token.value = scope[token.value].expr!;
       } else {
@@ -277,5 +279,11 @@ export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): st
       }
     }
   }
-  return tokens.map(t => t.value).join("");
+  return tokens;
+}
+
+export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
+  return compileExprToArray(expr, scope)
+    .map(t => t.value)
+    .join("");
 }

src/qweb/extensions.ts

@@ -58,7 +58,7 @@ export function makeHandlerCode(
     ctx.rootContext.shouldDefineUtils = true;
     const comp = `utils.getComponent(context)`;
     if (args) {
-      let argId = ctx.generateID();
+      const argId = ctx.generateID();
       ctx.addLine(`let args${argId} = [${ctx.formatExpression(args)}];`);
       code = `${comp}['${name}'](...args${argId}, e);`;
       putInCache = false;
@@ -67,8 +67,9 @@ export function makeHandlerCode(
     }
   } else {
     // if we get here, then it is an expression
+    // we need to capture every variable in it
     putInCache = false;
-    code = ctx.formatExpression(value);
+    code = ctx.captureExpression(value);
   }
   const modCode = mods.map(mod => modcodes[mod]).join("");
   let handler = `function (e) {if (!context.__owl__.isMounted){return}${modCode}${code}}`;
@@ -303,9 +304,20 @@ QWeb.addDirective({
 QWeb.addDirective({
   name: "key",
   priority: 45,
-  atNodeEncounter({ ctx, value }) {
-    let id = ctx.generateID();
-    ctx.addLine(`const nodeKey${id} = ${ctx.formatExpression(value)};`);
-    ctx.currentKey = `nodeKey${id}`;
+  atNodeEncounter({ ctx, value, node }) {
+    if (ctx.loopNumber === 0) {
+      ctx.keyStack.push(ctx.rootContext.hasKey0);
+      ctx.rootContext.hasKey0 = true;
+    }
+    ctx.addLine("{");
+    ctx.indent();
+    ctx.addLine(`let key${ctx.loopNumber} = ${ctx.formatExpression(value)};`);
+  },
+  finalize({ ctx }) {
+    ctx.dedent();
+    ctx.addLine("}");
+    if (ctx.loopNumber === 0) {
+      ctx.rootContext.hasKey0 = ctx.keyStack.pop() as boolean;
+    }
   }
 });

src/qweb/qweb.ts

@@ -86,6 +86,10 @@ interface Utils {
   [key: string]: any;
 }
 
+function isComponent(obj) {
+  return obj && obj.hasOwnProperty("__owl__");
+}
+
 const UTILS: Utils = {
   zero: Symbol("zero"),
   toObj(expr) {
@@ -122,10 +126,21 @@ const UTILS: Utils = {
       .join("");
   },
   getComponent(obj) {
-    while (obj && !obj.hasOwnProperty("__owl__")) {
+    while (obj && !isComponent(obj)) {
       obj = obj.__proto__;
     }
     return obj;
+  },
+  getScope(obj, property: string) {
+    const obj0 = obj;
+    while (obj && !obj.hasOwnProperty(property)) {
+      const newObj = obj.__proto__;
+      if (!newObj || isComponent(newObj)) {
+        return obj0;
+      }
+      obj = newObj;
+    }
+    return obj;
   }
 };
 
@@ -383,7 +398,12 @@ export class QWeb extends EventBus {
     });
   }
 
-  _compile(name: string, elem: Element, parentContext?: CompilationContext): CompiledTemplate {
+  _compile(
+    name: string,
+    elem: Element,
+    parentContext?: CompilationContext,
+    defineKey?: boolean
+  ): CompiledTemplate {
     const isDebug = elem.attributes.hasOwnProperty("t-debug");
     const ctx = new CompilationContext(name);
     if (elem.tagName !== "t") {
@@ -396,6 +416,10 @@ export class QWeb extends EventBus {
       ctx.hasParentWidget = true;
       ctx.shouldDefineResult = false;
       ctx.addLine(`let c${ctx.parentNode} = extra.parentNode;`);
+      if (defineKey) {
+        ctx.addLine(`let key0 = extra.key || "";`);
+        ctx.hasKey0 = true;
+      }
     }
     this._compileNode(elem, ctx);
 
@@ -473,9 +497,6 @@ export class QWeb extends EventBus {
       }
       return;
     }
-    if (ctx !== ctx.rootContext) {
-      ctx = ctx.subContext("currentKey", ctx.currentKey);
-    }
 
     const firstLetter = node.tagName[0];
     if (firstLetter === firstLetter.toUpperCase()) {
@@ -750,8 +771,8 @@ export class QWeb extends EventBus {
       }
     }
     let nodeID = ctx.generateID();
-    let nodeKey = ctx.currentKey || nodeID;
-    const parts = [`key:${nodeKey}`];
+    let key = ctx.loopNumber || ctx.hasKey0 ? `\`\${key${ctx.loopNumber}}_${nodeID}\`` : nodeID;
+    const parts = [`key:${key}`];
     if (attrs.length + tattrs.length > 0) {
       parts.push(`attrs:{${attrs.join(",")}}`);
     }
@@ -780,6 +801,9 @@ export class QWeb extends EventBus {
     ctx.addLine(`let vn${nodeID} = h('${node.nodeName}', p${nodeID}, c${nodeID});`);
     if (ctx.parentNode) {
       ctx.addLine(`c${ctx.parentNode}.push(vn${nodeID});`);
+    } else if (ctx.loopNumber || ctx.hasKey0) {
+      ctx.rootContext.shouldDefineResult = true;
+      ctx.addLine(`result = vn${nodeID};`);
     }
 
     return nodeID;

src/store.ts

@@ -132,7 +132,7 @@ export function useStore(selector, options: SelectorOptions = {}): any {
     __destroy.call(component, parent);
   };
 
-  if (typeof result !== "object") {
+  if (typeof result !== "object" || result === null) {
     return result;
   }
   return new Proxy(result, {

src/tags.ts

@@ -1,4 +1,5 @@
 import { QWeb } from "./qweb/index";
+import { registerSheet } from "./component/styles";
 
 /**
  * Owl Tags
@@ -25,3 +26,19 @@ export function xml(strings, ...args) {
   QWeb.registerTemplate(name, value);
   return name;
 }
+
+/**
+ * CSS tag helper for defining inline stylesheets.  With this, one can simply define
+ * an inline stylesheet with just the following code:
+ * ```js
+ *   class A extends Component {
+ *     static style = css`.component-a { color: red; }`;
+ *   }
+ * ```
+ */
+export function css(strings, ...args) {
+  const name = `__sheet__${QWeb.nextId++}`;
+  const value = String.raw(strings, ...args);
+  registerSheet(name, value);
+  return name;
+}

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

@@ -229,14 +229,14 @@ exports[`t-slot directive slots are rendered with proper context, part 2 1`] = `
     // Template name: \\"Link\\"
     let scope = Object.create(context);
     let h = this.h;
-    let _12 = scope['props'].to;
-    let c13 = [], p13 = {key:13,attrs:{href: _12}};
-    let vn13 = h('a', p13, c13);
-    const slot14 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot14) {
-        slot14.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c13, parent: extra.parent || context}));
+    let _11 = scope['props'].to;
+    let c12 = [], p12 = {key:12,attrs:{href: _11}};
+    let vn12 = h('a', p12, c12);
+    const slot13 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot13) {
+        slot13.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c12, parent: extra.parent || context}));
     }
-    return vn13;
+    return vn12;
 }"
 `;
 
@@ -263,42 +263,42 @@ exports[`t-slot directive slots are rendered with proper context, part 2 2`] = `
     }
     let _length4 = _4.length;
     let _origScope6 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length4; i1++) {
         scope.user_first = i1 === 0
         scope.user_last = i1 === _length4 - 1
         scope.user_index = i1
         scope.user = _4[i1]
         scope.user_value = _5[i1]
-        const nodeKey7 = scope['user'].id;
-        let c8 = [], p8 = {key:nodeKey7};
-        let vn8 = h('li', p8, c8);
-        c2.push(vn8);
+        let key1 = scope['user'].id;
+        let c7 = [], p7 = {key:\`\${key1}_7\`};
+        let vn7 = h('li', p7, c7);
+        c2.push(vn7);
         // Component 'Link'
-        let k10 = \`__10__\` + nodeKey7;
-        let w9 = k10 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k10]] : false;
-        let props9 = {to:'/user/'+scope['user'].id};
-        if (w9 && w9.__owl__.currentFiber && !w9.__owl__.vnode) {
-            w9.destroy();
-            w9 = false;
+        let k9 = \`__9__\${key1}__\`;
+        let w8 = k9 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k9]] : false;
+        let props8 = {to:'/user/'+scope['user'].id};
+        if (w8 && w8.__owl__.currentFiber && !w8.__owl__.vnode) {
+            w8.destroy();
+            w8 = false;
         }
-        if (w9) {
-            w9.__updateProps(props9, extra.fiber, Object.assign(Object.create(context), scope));
-            let pvnode = w9.__owl__.pvnode;
-            c8.push(pvnode);
+        if (w8) {
+            w8.__updateProps(props8, extra.fiber, Object.assign(Object.create(context), scope));
+            let pvnode = w8.__owl__.pvnode;
+            c7.push(pvnode);
         } else {
-            let componentKey9 = \`Link\`;
-            let W9 = context.constructor.components[componentKey9] || QWeb.components[componentKey9]|| scope['Link'];
-            if (!W9) {throw new Error('Cannot find the definition of component \\"' + componentKey9 + '\\"')}
-            w9 = new W9(parent, props9);
-            parent.__owl__.cmap[k10] = w9.__owl__.id;
-            w9.__owl__.slotId = 1;
-            let fiber = w9.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k10, hook: {remove() {},destroy(vn) {w9.destroy();}}});
-            c8.push(pvnode);
-            w9.__owl__.pvnode = pvnode;
+            let componentKey8 = \`Link\`;
+            let W8 = context.constructor.components[componentKey8] || QWeb.components[componentKey8]|| scope['Link'];
+            if (!W8) {throw new Error('Cannot find the definition of component \\"' + componentKey8 + '\\"')}
+            w8 = new W8(parent, props8);
+            parent.__owl__.cmap[k9] = w8.__owl__.id;
+            w8.__owl__.slotId = 1;
+            let fiber = w8.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            let pvnode = h('dummy', {key: k9, hook: {remove() {},destroy(vn) {w8.destroy();}}});
+            c7.push(pvnode);
+            w8.__owl__.pvnode = pvnode;
         }
-        w9.__owl__.parentLastFiberId = extra.fiber.id;
+        w8.__owl__.parentLastFiberId = extra.fiber.id;
     }
     scope = _origScope6;
     return vn1;
@@ -311,11 +311,11 @@ exports[`t-slot directive slots are rendered with proper context, part 2 3`] = `
     // Template name: \\"slot_default_template\\"
     let scope = Object.create(context);
     let h = this.h;
-    let c8 = extra.parentNode;
-    c8.push({text: \`User \`});
-    let _11 = scope['user'].name;
-    if (_11 != null) {
-        c8.push({text: _11});
+    let c7 = extra.parentNode;
+    c7.push({text: \`User \`});
+    let _10 = scope['user'].name;
+    if (_10 != null) {
+        c7.push({text: _10});
     }
 }"
 `;
@@ -326,14 +326,14 @@ exports[`t-slot directive slots are rendered with proper context, part 3 1`] = `
     // Template name: \\"Link\\"
     let scope = Object.create(context);
     let h = this.h;
-    let _11 = scope['props'].to;
-    let c12 = [], p12 = {key:12,attrs:{href: _11}};
-    let vn12 = h('a', p12, c12);
-    const slot13 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot13) {
-        slot13.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c12, parent: extra.parent || context}));
+    let _10 = scope['props'].to;
+    let c11 = [], p11 = {key:11,attrs:{href: _10}};
+    let vn11 = h('a', p11, c11);
+    const slot12 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot12) {
+        slot12.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c11, parent: extra.parent || context}));
     }
-    return vn12;
+    return vn11;
 }"
 `;
 
@@ -360,43 +360,43 @@ exports[`t-slot directive slots are rendered with proper context, part 3 2`] = `
     }
     let _length4 = _4.length;
     let _origScope6 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length4; i1++) {
         scope.user_first = i1 === 0
         scope.user_last = i1 === _length4 - 1
         scope.user_index = i1
         scope.user = _4[i1]
         scope.user_value = _5[i1]
-        const nodeKey7 = scope['user'].id;
-        let c8 = [], p8 = {key:nodeKey7};
-        let vn8 = h('li', p8, c8);
-        c2.push(vn8);
-        scope.userdescr = 'User '+scope['user'].name;
+        let key1 = scope['user'].id;
+        let c7 = [], p7 = {key:\`\${key1}_7\`};
+        let vn7 = h('li', p7, c7);
+        c2.push(vn7);
+        utils.getScope(scope, 'userdescr').userdescr = 'User '+scope['user'].name;
         // Component 'Link'
-        let k10 = \`__10__\` + nodeKey7;
-        let w9 = k10 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k10]] : false;
-        let props9 = {to:'/user/'+scope['user'].id};
-        if (w9 && w9.__owl__.currentFiber && !w9.__owl__.vnode) {
-            w9.destroy();
-            w9 = false;
+        let k9 = \`__9__\${key1}__\`;
+        let w8 = k9 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k9]] : false;
+        let props8 = {to:'/user/'+scope['user'].id};
+        if (w8 && w8.__owl__.currentFiber && !w8.__owl__.vnode) {
+            w8.destroy();
+            w8 = false;
         }
-        if (w9) {
-            w9.__updateProps(props9, extra.fiber, Object.assign(Object.create(context), scope));
-            let pvnode = w9.__owl__.pvnode;
-            c8.push(pvnode);
+        if (w8) {
+            w8.__updateProps(props8, extra.fiber, Object.assign(Object.create(context), scope));
+            let pvnode = w8.__owl__.pvnode;
+            c7.push(pvnode);
         } else {
-            let componentKey9 = \`Link\`;
-            let W9 = context.constructor.components[componentKey9] || QWeb.components[componentKey9]|| scope['Link'];
-            if (!W9) {throw new Error('Cannot find the definition of component \\"' + componentKey9 + '\\"')}
-            w9 = new W9(parent, props9);
-            parent.__owl__.cmap[k10] = w9.__owl__.id;
-            w9.__owl__.slotId = 1;
-            let fiber = w9.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k10, hook: {remove() {},destroy(vn) {w9.destroy();}}});
-            c8.push(pvnode);
-            w9.__owl__.pvnode = pvnode;
+            let componentKey8 = \`Link\`;
+            let W8 = context.constructor.components[componentKey8] || QWeb.components[componentKey8]|| scope['Link'];
+            if (!W8) {throw new Error('Cannot find the definition of component \\"' + componentKey8 + '\\"')}
+            w8 = new W8(parent, props8);
+            parent.__owl__.cmap[k9] = w8.__owl__.id;
+            w8.__owl__.slotId = 1;
+            let fiber = w8.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            let pvnode = h('dummy', {key: k9, hook: {remove() {},destroy(vn) {w8.destroy();}}});
+            c7.push(pvnode);
+            w8.__owl__.pvnode = pvnode;
         }
-        w9.__owl__.parentLastFiberId = extra.fiber.id;
+        w8.__owl__.parentLastFiberId = extra.fiber.id;
     }
     scope = _origScope6;
     return vn1;
@@ -409,9 +409,9 @@ exports[`t-slot directive slots are rendered with proper context, part 3 3`] = `
     // Template name: \\"slot_default_template\\"
     let scope = Object.create(context);
     let h = this.h;
-    let c8 = extra.parentNode;
+    let c7 = extra.parentNode;
     if (scope.userdescr != null) {
-        c8.push({text: scope.userdescr});
+        c7.push({text: scope.userdescr});
     }
 }"
 `;

tests/component/component.test.ts

@@ -147,6 +147,21 @@ describe("basic widget properties", () => {
     expect(fixture.innerHTML).toBe("<div>1<button>Inc</button></div>");
   });
 
+  test("can handle empty props", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`<div><Child val=""/></div>`;
+      static components = { Child };
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(env.qweb.templates[Parent.template].fn.toString()).toMatchSnapshot();
+    expect(fixture.innerHTML).toBe("<div><span></span></div>");
+  });
+
   test("cannot be clicked on and updated if not in DOM", async () => {
     class Counter extends Component<any, any> {
       static template = xml`
@@ -322,6 +337,36 @@ describe("basic widget properties", () => {
     console.warn = warn;
   });
 
+  test("reconciliation alg works for t-foreach in t-foreach, 2", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`<div><t t-esc="props.row + '_' + props.col"/></div>`;
+    }
+
+    class Parent extends Component<any, any> {
+      static template = xml`
+        <div>
+          <p t-foreach="state.rows" t-as="row" t-key="row">
+            <p t-foreach="state.cols" t-as="col" t-key="col">
+                <Child row="row" col="col"/>
+              </p>
+            </p>
+        </div>`;
+      static components = { Child };
+      state = useState({ rows: [1, 2], cols: ["a", "b"] });
+    }
+
+    const widget = new Parent();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(
+      "<div><p><p><div>1_a</div></p><p><div>1_b</div></p></p><p><p><div>2_a</div></p><p><div>2_b</div></p></p></div>"
+    );
+    widget.state.rows = [2, 1];
+    await nextTick();
+    expect(fixture.innerHTML).toBe(
+      "<div><p><p><div>2_a</div></p><p><div>2_b</div></p></p><p><p><div>1_a</div></p><p><div>1_b</div></p></p></div>"
+    );
+  });
+
   test("same t-keys in two different places", async () => {
     class Child extends Component<any, any> {
       static template = xml`<span><t t-esc="props.blip"/></span>`;
@@ -339,6 +384,7 @@ describe("basic widget properties", () => {
     const widget = new Parent();
     await widget.mount(fixture);
     expect(fixture.innerHTML).toBe("<div><div><span>1</span></div><div><span>2</span></div></div>");
+    expect(env.qweb.templates[Parent.template].fn.toString()).toMatchSnapshot();
   });
 
   test("t-key on a component with t-if, and a sibling component", async () => {
@@ -2624,6 +2670,359 @@ describe("other directives with t-component", () => {
     await nextTick(); // wait for changes triggered in mounted to be applied
     expect(fixture.innerHTML).toBe("<div><span>B0</span><span>B1</span></div>");
   });
+
+  test("t-set outside modified in t-foreach", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-foreach="state.values" t-as="val" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="iter + 1"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>InLoop: 0</p><p>InLoop: 1</p><p>EndLoop: 2</p></div>");
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-set outside modified in t-if", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-set="flag" t-value="state.flag" />
+        <t t-if="flag === 'if'">
+          <t t-set="iter" t-value="2"/>
+        </t>
+        <t t-elif="flag === 'elif'">
+          <t t-set="iter" t-value="3"/>
+        </t>
+        <t t-else="">
+          <t t-set="iter" t-value="4"/>
+        </t>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+
+      state = { flag: "if" };
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>2</p></div>");
+    widget.state.flag = "elif";
+    await widget.render();
+    expect(fixture.innerHTML).toBe("<div><p>3</p></div>");
+    widget.state.flag = "false";
+    await widget.render();
+    expect(fixture.innerHTML).toBe("<div><p>4</p></div>");
+  });
+
+  test("t-set in t-if", async () => {
+    // Weird that code block within 'if' leaks outside of it
+    // Python does the same
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="flag" t-value="state.flag" />
+        <t t-if="flag === 'if'">
+          <t t-set="iter" t-value="2"/>
+        </t>
+        <t t-elif="flag === 'elif'">
+          <t t-set="iter" t-value="3"/>
+        </t>
+        <t t-else="">
+          <t t-set="iter" t-value="4"/>
+        </t>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+
+      state = { flag: "if" };
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>2</p></div>");
+    widget.state.flag = "elif";
+    await widget.render();
+    expect(fixture.innerHTML).toBe("<div><p>3</p></div>");
+    widget.state.flag = "false";
+    await widget.render();
+    expect(fixture.innerHTML).toBe("<div><p>4</p></div>");
+  });
+
+  test("t-set can't alter component", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <p><t t-esc="iter"/></p>
+        <t t-set="iter" t-value="5"/>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+
+      iter = 1;
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>1</p><p>5</p></div>");
+    expect(widget.iter).toBe(1);
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-set can't alter from within callee", async () => {
+    env.qweb.addTemplate(
+      "ChildWidget",
+      `<div><t t-esc="iter"/><t t-set="iter" t-value="'called'"/><t t-esc="iter"/></div>`
+    );
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="'source'"/>
+        <p><t t-esc="iter"/></p>
+        <t t-call="ChildWidget"/>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>source</p><div>sourcecalled</div><p>source</p></div>");
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-set can't alter in t-call body", async () => {
+    env.qweb.addTemplate(
+      "ChildWidget",
+      `<div><t t-esc="iter"/><t t-set="iter" t-value="'called'"/><t t-esc="iter"/></div>`
+    );
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="'source'"/>
+        <p><t t-esc="iter"/></p>
+        <t t-call="ChildWidget">
+          <t t-set="iter" t-value="'inCall'"/>
+        </t>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>source</p><div>inCallcalled</div><p>source</p></div>");
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("slot setted value (with t-set) not accessible with t-esc", async () => {
+    class ChildWidget extends Component<any, any> {
+      static template = xml`<div><t t-esc="iter"/><t t-set="iter" t-value="'called'"/><t t-esc="iter"/></div>`;
+    }
+    class SomeWidget extends Component<any, any> {
+      static components = { ChildWidget };
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="'source'"/>
+        <p><t t-esc="iter"/></p>
+        <ChildWidget>
+          <t t-set="iter" t-value="'inCall'"/>
+        </ChildWidget>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>source</p><div>called</div><p>source</p></div>");
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-set not altered by child widget", async () => {
+    let child;
+    class ChildWidget extends Component<any, any> {
+      static template = xml`<div><t t-esc="iter"/><t t-set="iter" t-value="'called'"/><t t-esc="iter"/></div>`;
+      iter = "child";
+      constructor() {
+        super(...arguments);
+        child = this;
+      }
+    }
+    class SomeWidget extends Component<any, any> {
+      static components = { ChildWidget };
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="'source'"/>
+        <p><t t-esc="iter"/></p>
+        <ChildWidget/>
+        <p><t t-esc="iter"/></p>
+      </div>`;
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><p>source</p><div>childcalled</div><p>source</p></div>");
+    expect(child.iter).toBe("child");
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-set outside modified in t-foreach increment-after operator", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-foreach="state.values" t-as="val" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="iter++"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><p>InLoop: 0</p><p>InLoop: 1</p><p>EndLoop: 0</p></div>");
+  });
+
+  test("t-set outside modified in t-foreach increment-before operator", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="0"/>
+        <t t-foreach="state.values" t-as="val" t-key="val">
+          <p>InLoop: <t t-esc="iter"/></p>
+          <t t-set="iter" t-value="++iter"/>
+        </t>
+        <p>EndLoop: <t t-esc="iter"/></p>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><p>InLoop: 0</p><p>InLoop: 1</p><p>EndLoop: 1</p></div>");
+  });
+
+  test("t-on expression in t-foreach", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <div t-foreach="state.values" t-as="val" t-key="val">
+          <t t-esc="val_index"/>: <t t-esc="val + ''"/>
+          <button t-on-click="otherState.vals.push(val)">Expr</button>
+        </div>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+      otherState = { vals: [] };
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe(
+      "<div><div>0: a<button>Expr</button></div><div>1: b<button>Expr</button></div></div>"
+    );
+    expect(widget.otherState.vals).toStrictEqual([]);
+    const buttons = fixture.querySelectorAll("button");
+    buttons[0].click();
+    buttons[1].click();
+    expect(widget.otherState.vals).toStrictEqual(["a", "b"]);
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-on expression in t-foreach with t-set", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="bossa" t-value="'nova'"/>
+        <div t-foreach="state.values" t-as="val" t-key="val">
+          <t t-set="bossa" t-value="bossa + '_' + val_index" />
+          <t t-esc="val_index"/>: <t t-esc="val + ''"/>
+          <button t-on-click="otherState.vals.push(val + '_' + bossa)">Expr</button>
+        </div>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+      otherState = { vals: [] };
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe(
+      "<div><div>0: a<button>Expr</button></div><div>1: b<button>Expr</button></div></div>"
+    );
+    expect(widget.otherState.vals).toStrictEqual([]);
+    const buttons = fixture.querySelectorAll("button");
+    buttons[0].click();
+    buttons[1].click();
+    expect(widget.otherState.vals).toStrictEqual(["a_nova_0", "b_nova_0_1"]);
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-on method call in t-foreach", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <div t-foreach="state.values" t-as="val" t-key="val">
+          <t t-esc="val_index"/>: <t t-esc="val + ''"/>
+          <button t-on-click="addVal(val)">meth call</button>
+        </div>
+      </div>`;
+
+      state = useState({ values: ["a", "b"] });
+      otherState = { vals: new Array<string>() };
+
+      addVal(val: string) {
+        this.otherState.vals.push(val);
+      }
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe(
+      "<div><div>0: a<button>meth call</button></div><div>1: b<button>meth call</button></div></div>"
+    );
+    expect(widget.otherState.vals).toStrictEqual([]);
+    const buttons = fixture.querySelectorAll("button");
+    buttons[0].click();
+    buttons[1].click();
+    expect(widget.otherState.vals).toStrictEqual(["a", "b"]);
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-on expression captured in t-foreach", async () => {
+    class SomeWidget extends Component<any, any> {
+      static template = xml`
+      <div>
+        <t t-set="iter" t-value="0" />
+        <div t-foreach="arr" t-as="val" t-key="val">
+          <button t-on-click="otherState.vals.push(iter + '_' + iter)">expr</button>
+          <t t-set="iter" t-value="iter + 1" />
+        </div>
+      </div>`;
+
+      arr = ["a", "b"];
+      otherState = { vals: new Array<string>() };
+    }
+    const widget = new SomeWidget();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe(
+      "<div><div><button>expr</button></div><div><button>expr</button></div></div>"
+    );
+    expect(widget.otherState.vals).toStrictEqual([]);
+    const buttons = fixture.querySelectorAll("button");
+    buttons[0].click();
+    buttons[1].click();
+    expect(widget.otherState.vals).toStrictEqual(["0_0", "1_1"]);
+    expect(QWeb.TEMPLATES[SomeWidget.template].fn.toString()).toMatchSnapshot();
+  });
 });
 
 describe("random stuff/miscellaneous", () => {
@@ -4418,6 +4817,28 @@ describe("t-model directive", () => {
     expect(comp.state[2].f).toBe(false);
     expect(env.qweb.templates[SomeComponent.template].fn.toString()).toMatchSnapshot();
   });
+
+  test("two inputs in a div with a t-key", async () => {
+    class SomeComponent extends Component<any, any> {
+      static template = xml`
+        <div t-key="'key'">
+          <input class="a" t-if="state.flag"/>
+          <input class="b" t-if="!state.flag"/>
+        </div>
+      `;
+      state = useState({ flag: true });
+    }
+    const comp = new SomeComponent();
+    await comp.mount(fixture);
+    expect(fixture.innerHTML).toBe('<div><input class="a"></div>');
+    expect(env.qweb.templates[SomeComponent.template].fn.toString()).toMatchSnapshot();
+    fixture.querySelector("input")!.value = "asdf";
+    expect(fixture.querySelector("input")!.value).toBe("asdf");
+    comp.state.flag = false;
+    await nextTick();
+    expect(fixture.innerHTML).toBe('<div><input class="b"></div>');
+    expect(fixture.querySelector("input")!.value).toBe("");
+  });
 });
 
 describe("environment and plugins", () => {
@@ -5599,6 +6020,26 @@ describe("t-call", () => {
     expect(env.qweb.subTemplates["sub"].toString()).toMatchSnapshot();
   });
 
+  test("t-call in t-foreach and children component", async () => {
+    env.qweb.addTemplate("sub", `<Child val="val"/>`);
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Child };
+      static template = xml`
+        <div>
+          <t t-foreach="['a', 'b', 'c']" t-as="val" t-key="val">
+            <t t-call="sub"/>
+          </t>
+        </div>`;
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><span>a</span><span>b</span><span>c</span></div>");
+  });
+
   test("parent is set within t-call with no parentNode", async () => {
     env.qweb.addTemplate("sub", `<Child/>`);
     let child;
@@ -5638,4 +6079,29 @@ describe("t-call", () => {
 
     fixture.querySelector("p")!.click();
   });
+
+  test("sub components in two t-calls", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+    }
+
+    env.qweb.addTemplate("sub", `<Child val="state.val"/>`);
+    class Parent extends Component<any, any> {
+      static template = xml`
+        <div>
+          <t t-if="state.val===1">
+            <t t-call="sub"/>
+          </t>
+          <div t-else=""><t t-call="sub"/></div>
+        </div>`;
+      static components = { Child };
+      state = useState({ val: 1 });
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><span>1</span></div>");
+    parent.state.val = 2;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div><span>2</span></div></div>");
+  });
 });

tests/component/slots.test.ts

@@ -19,13 +19,6 @@ let env: Env;
 beforeEach(() => {
   fixture = makeTestFixture();
   env = makeTestEnv();
-  env.qweb.addTemplate("Component<any,any>", "<div></div>");
-  env.qweb.addTemplate(
-    "Counter",
-    `<div><t t-esc="state.counter"/><button t-on-click="inc">Inc</button></div>`
-  );
-  env.qweb.addTemplate("WidgetA", `<div>Hello<t t-component="b"/></div>`);
-  env.qweb.addTemplate("WidgetB", `<div>world</div>`);
   Component.env = env;
 });
 

tests/component/styles.test.ts

@@ -0,0 +1,170 @@
+import { Component, Env } from "../../src/component/component";
+import { processSheet } from "../../src/component/styles";
+import { xml, css } from "../../src/tags";
+import { makeTestFixture, makeTestEnv } from "../helpers";
+
+//------------------------------------------------------------------------------
+// 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: an Env, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+  Component.env = env;
+  document.head.innerHTML = "";
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+describe("styles and component", () => {
+  test("can define an inline stylesheet", async () => {
+    class App extends Component<any, any> {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+        }
+      `;
+    }
+    expect(document.head.innerHTML).toBe("");
+    const app = new App();
+
+    expect(document.head.innerHTML).toBe(`<style component=\"App\">.app {
+  color: red;
+}</style>`);
+
+    await app.mount(fixture);
+    const style = getComputedStyle(app.el!);
+    expect(style.color).toBe("red");
+    expect(fixture.innerHTML).toBe('<div class="app">text</div>');
+  });
+
+  test("inherited components properly apply css", async () => {
+    class App extends Component<any, any> {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+        }
+      `;
+    }
+    class SubApp extends App {
+      static style = css`
+        .app {
+          font-weight: bold;
+        }
+      `;
+    }
+    expect(document.head.innerHTML).toBe("");
+    const app = new SubApp();
+
+    expect(document.head.innerHTML).toBe(`<style component=\"SubApp\">.app {
+  font-weight: bold;
+}</style><style component=\"App\">.app {
+  color: red;
+}</style>`);
+
+    await app.mount(fixture);
+    const style = getComputedStyle(app.el!);
+    expect(style.color).toBe("red");
+    expect(style.fontWeight).toBe("bold");
+    expect(fixture.innerHTML).toBe('<div class="app">text</div>');
+  });
+
+  test("get a meaningful error message if css helper is missing", async () => {
+    class App extends Component<any, any> {
+      static template = xml`<div class="app">text</div>`;
+      static style = `.app {color: red;}`;
+    }
+    let error;
+    try {
+      new App();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe(
+      "Invalid css stylesheet for component 'App'. Did you forget to use the 'css' tag helper?"
+    );
+  });
+
+  test("inline stylesheets are processed", async () => {
+    class App extends Component<any, any> {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+          .some-class {
+            font-weight: bold;
+            width: 40px;
+          }
+
+          display: block;
+        }
+      `;
+    }
+    new App();
+
+    expect(document.head.querySelector("style")!.innerHTML).toBe(`.app {
+  color: red;
+}
+.app .some-class {
+  font-weight: bold;
+  width: 40px;
+}
+.app {
+  display: block;
+}`);
+  });
+
+  test("properly handle rules with commas", async () => {
+    const sheet = processSheet(`.parent-a, .parent-b {
+      .child-a, .child-b {
+        color: red;
+      }
+    }`);
+
+    expect(sheet)
+      .toBe(`.parent-a .child-a, .parent-a .child-b, .parent-b .child-a, .parent-b .child-b {
+  color: red;
+}`);
+  });
+
+  test("handle & selector", async () => {
+    let sheet = processSheet(`.btn {
+      &.danger {
+        color: red;
+      }
+    }`);
+
+    expect(sheet).toBe(`.btn.danger {
+  color: red;
+}`);
+
+    sheet = processSheet(`.some-class {
+      &.btn {
+        .other-class ~ & {
+          color: red;
+        }
+      }
+    }`);
+
+    expect(sheet).toBe(`.other-class ~ .some-class.btn {
+  color: red;
+}`);
+  });
+});

tests/hooks.test.ts

@@ -9,7 +9,8 @@ import {
   onWillPatch,
   onWillStart,
   onWillUpdateProps,
-  useSubEnv
+  useSubEnv,
+  useExternalListener
 } from "../src/hooks";
 import { xml } from "../src/tags";
 
@@ -592,4 +593,39 @@ describe("hooks", () => {
     expect(fixture.innerHTML).toBe("<div><span>2</span></div>");
     expect(steps).toEqual(["onWillStart", "onWillUpdateProps"]);
   });
+
+  test("useExternalListener", async () => {
+    let n = 0;
+
+    class MyComponent extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.value"/></span>`;
+      constructor(parent, props) {
+        super(parent, props);
+        useExternalListener(window as any, "click", this.increment);
+      }
+      increment() {
+        n++;
+      }
+    }
+    class App extends Component<any, any> {
+      static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
+      static components = { MyComponent };
+      state = useState({ flag: false });
+    }
+
+    const app = new App();
+    await app.mount(fixture);
+
+    expect(n).toBe(0);
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(0);
+    app.state.flag = true;
+    await nextTick();
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(1);
+    app.state.flag = false;
+    await nextTick();
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(1);
+  });
 });

tests/qweb/__snapshots__/qweb.test.ts.snap

@@ -421,13 +421,14 @@ exports[`foreach does not pollute the rendering context 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
+        let key1 = i1;
         let _6 = scope['item'];
         if (_6 != null) {
             c1.push({text: _6});
@@ -455,20 +456,20 @@ exports[`foreach iterate on items (on a element node) 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
-        const nodeKey6 = scope['item'];
-        let c7 = [], p7 = {key:nodeKey6};
-        let vn7 = h('span', p7, c7);
-        c1.push(vn7);
-        let _8 = scope['item'];
-        if (_8 != null) {
-            c7.push({text: _8});
+        let key1 = scope['item'];
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
+        let vn6 = h('span', p6, c6);
+        c1.push(vn6);
+        let _7 = scope['item'];
+        if (_7 != null) {
+            c6.push({text: _7});
         }
     }
     scope = _origScope5;
@@ -493,13 +494,14 @@ exports[`foreach iterate on items 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
+        let key1 = i1;
         c1.push({text: \` [\`});
         let _6 = scope['item_index'];
         if (_6 != null) {
@@ -539,13 +541,14 @@ exports[`foreach iterate, dict param 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
+        let key1 = i1;
         c1.push({text: \` [\`});
         let _6 = scope['item_index'];
         if (_6 != null) {
@@ -585,13 +588,14 @@ exports[`foreach iterate, position 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.elem_first = i1 === 0
         scope.elem_last = i1 === _length3 - 1
         scope.elem_index = i1
         scope.elem = _3[i1]
         scope.elem_value = _4[i1]
+        let key1 = i1;
         c1.push({text: \` -\`});
         if (scope['elem_first']) {
             c1.push({text: \` first\`});
@@ -628,13 +632,14 @@ exports[`foreach t-foreach in t-forach 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.number_first = i1 === 0
         scope.number_last = i1 === _length3 - 1
         scope.number_index = i1
         scope.number = _3[i1]
         scope.number_value = _4[i1]
+        let key1 = i1;
         let _6 = scope['letters'];
         if (!_6) { throw new Error('QWeb error: Invalid loop expression')}
         let _7 = _8 = _6;
@@ -644,13 +649,14 @@ exports[`foreach t-foreach in t-forach 1`] = `
         }
         let _length7 = _7.length;
         let _origScope9 = scope;
-        scope = Object.assign(Object.create(context), scope);
+        scope = Object.create(scope);
         for (let i2 = 0; i2 < _length7; i2++) {
             scope.letter_first = i2 === 0
             scope.letter_last = i2 === _length7 - 1
             scope.letter_index = i2
             scope.letter = _7[i2]
             scope.letter_value = _8[i2]
+            let key2 = i2;
             c1.push({text: \` [\`});
             let _10 = scope['number'];
             if (_10 != null) {
@@ -686,14 +692,15 @@ exports[`foreach warn if no key in some case 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
-        let c6 = [], p6 = {key:6};
+        let key1 = i1;
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
         let vn6 = h('span', p6, c6);
         c1.push(vn6);
         let _7 = scope['item'];
@@ -727,7 +734,7 @@ exports[`loading templates can load a few templates from a xml string 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1};
     let vn1 = h('ul', p1, c1);
-    this.subTemplates['items'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['items'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__4__'}));
     return vn1;
 }"
 `;
@@ -750,14 +757,15 @@ exports[`misc global 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.value_first = i1 === 0
         scope.value_last = i1 === _length3 - 1
         scope.value_index = i1
         scope.value = _3[i1]
         scope.value_value = _4[i1]
-        let c6 = [], p6 = {key:6};
+        let key1 = i1;
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
         let vn6 = h('span', p6, c6);
         c1.push(vn6);
         let _7 = scope['value'];
@@ -774,23 +782,27 @@ exports[`misc global 1`] = `
                     scope = Object.assign(Object.create(context), scope);
                     {
                         let c__0 = [];
-                        scope.foo = 'aaa';
+                        utils.getScope(scope, 'foo').foo = 'aaa';
                         scope[utils.zero] = c__0;
                     }
-                    this.subTemplates['_callee-uses-foo'].call(this, scope, Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context)}));
+                    let k14 = \`__14__\${key1}__\`;
+                    this.subTemplates['_callee-uses-foo'].call(this, scope, Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context), key: k14}));
                     scope = _origScope13;
                 }
-                this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context)}));
-                scope.foo = 'bbb';
-                this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context)}));
+                let k15 = \`__15__\${key1}__\`;
+                this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context), key: k15}));
+                utils.getScope(scope, 'foo').foo = 'bbb';
+                let k16 = \`__16__\${key1}__\`;
+                this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c__0, parent: utils.getComponent(context), key: k16}));
                 scope[utils.zero] = c__0;
             }
-            this.subTemplates['_callee-asc'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+            let k17 = \`__17__\${key1}__\`;
+            this.subTemplates['_callee-asc'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: k17}));
             scope = _origScope10;
         }
     }
     scope = _origScope5;
-    this.subTemplates['_callee-asc-toto'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['_callee-asc-toto'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__20__'}));
     return vn1;
 }"
 `;
@@ -1029,7 +1041,7 @@ exports[`t-call (template calling basic caller 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
-    this.subTemplates['_basic-callee'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['_basic-callee'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__3__'}));
     return vn1;
 }"
 `;
@@ -1040,7 +1052,8 @@ exports[`t-call (template calling basic caller 2`] = `
     // Template name: \\"_basic-callee\\"
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('span', p2, c2);
     c1.push(vn2);
     c2.push({text: \`ok\`});
@@ -1056,7 +1069,7 @@ exports[`t-call (template calling basic caller, no parent node 1`] = `
     let result;
     let h = this.h;
     result = []
-    this.subTemplates['_basic-callee'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context)}));
+    this.subTemplates['_basic-callee'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context), key: '__3__'}));
     result = result[0]
     return result;
 }"
@@ -1068,7 +1081,8 @@ exports[`t-call (template calling basic caller, no parent node 2`] = `
     // Template name: \\"_basic-callee\\"
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('div', p2, c2);
     c1.push(vn2);
     c2.push({text: \`ok\`});
@@ -1100,7 +1114,7 @@ exports[`t-call (template calling call with several sub nodes on same line 1`] =
             c5.push({text: \`yay\`});
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['SubTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['SubTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__6__'}));
         scope = _origScope3;
     }
     return vn1;
@@ -1115,7 +1129,8 @@ exports[`t-call (template calling call with several sub nodes on same line 2`] =
     let scope = Object.create(context);
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('div', p2, c2);
     c1.push(vn2);
     c2.push(...scope[utils.zero]);
@@ -1132,23 +1147,23 @@ exports[`t-call (template calling cascading t-call t-raw='0' 1`] = `
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
     {
-        let _origScope10 = scope;
+        let _origScope12 = scope;
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            let c11 = [], p11 = {key:11};
-            let vn11 = h('span', p11, c11);
-            c__0.push(vn11);
-            c11.push({text: \`hey\`});
+            let c13 = [], p13 = {key:13};
+            let vn13 = h('span', p13, c13);
+            c__0.push(vn13);
+            c13.push({text: \`hey\`});
             c__0.push({text: \` \`});
-            let c12 = [], p12 = {key:12};
-            let vn12 = h('span', p12, c12);
-            c__0.push(vn12);
-            c12.push({text: \`yay\`});
+            let c14 = [], p14 = {key:14};
+            let vn14 = h('span', p14, c14);
+            c__0.push(vn14);
+            c14.push({text: \`yay\`});
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['SubTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
-        scope = _origScope10;
+        this.subTemplates['SubTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__15__'}));
+        scope = _origScope12;
     }
     return vn1;
 }"
@@ -1164,7 +1179,7 @@ exports[`t-call (template calling inherit context 1`] = `
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
     scope.foo = 1;
-    this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['_callee-uses-foo'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__2__'}));
     return vn1;
 }"
 `;
@@ -1183,7 +1198,7 @@ exports[`t-call (template calling recursive template, part 1 1`] = `
     c1.push(vn2);
     c2.push({text: \`hey\`});
     if (false) {
-        this.subTemplates['recursive'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['recursive'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__6__'}));
     }
     return vn1;
 }"
@@ -1197,15 +1212,17 @@ exports[`t-call (template calling recursive template, part 1 2`] = `
     let scope = Object.create(context);
     let h = this.h;
     let c1 = extra.parentNode;
-    let c3 = [], p3 = {key:3};
+    let key0 = extra.key || \\"\\";
+    let c3 = [], p3 = {key:\`\${key0}_3\`};
     let vn3 = h('div', p3, c3);
     c1.push(vn3);
-    let c4 = [], p4 = {key:4};
+    let c4 = [], p4 = {key:\`\${key0}_4\`};
     let vn4 = h('span', p4, c4);
     c3.push(vn4);
     c4.push({text: \`hey\`});
     if (false) {
-        this.subTemplates['recursive'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c3, parent: utils.getComponent(context)}));
+        let k5 = \`__5__\${key0}__\`;
+        this.subTemplates['recursive'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c3, parent: utils.getComponent(context), key: k5}));
     }
 }"
 `;
@@ -1220,15 +1237,15 @@ exports[`t-call (template calling recursive template, part 2 1`] = `
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
     {
-        let _origScope10 = scope;
+        let _origScope11 = scope;
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            scope.node = scope['root'];
+            utils.getScope(scope, 'node').node = scope['root'];
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
-        scope = _origScope10;
+        this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__12__'}));
+        scope = _origScope11;
     }
     return vn1;
 }"
@@ -1242,10 +1259,11 @@ exports[`t-call (template calling recursive template, part 2 2`] = `
     let scope = Object.create(context);
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('div', p2, c2);
     c1.push(vn2);
-    let c3 = [], p3 = {key:3};
+    let c3 = [], p3 = {key:\`\${key0}_3\`};
     let vn3 = h('p', p3, c3);
     c2.push(vn3);
     let _4 = scope['node'].val;
@@ -1261,22 +1279,24 @@ exports[`t-call (template calling recursive template, part 2 2`] = `
     }
     let _length6 = _6.length;
     let _origScope8 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length6; i1++) {
         scope.subtree_first = i1 === 0
         scope.subtree_last = i1 === _length6 - 1
         scope.subtree_index = i1
         scope.subtree = _6[i1]
         scope.subtree_value = _7[i1]
+        let key1 = i1;
         {
             let _origScope9 = scope;
             scope = Object.assign(Object.create(context), scope);
             {
                 let c__0 = [];
-                scope.node = scope['subtree'];
+                utils.getScope(scope, 'node').node = scope['subtree'];
                 scope[utils.zero] = c__0;
             }
-            this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c2, parent: utils.getComponent(context)}));
+            let k10 = \`__10__\${key0}__\${key1}__\`;
+            this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c2, parent: utils.getComponent(context), key: k10}));
             scope = _origScope9;
         }
     }
@@ -1294,15 +1314,15 @@ exports[`t-call (template calling recursive template, part 3 1`] = `
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
     {
-        let _origScope10 = scope;
+        let _origScope11 = scope;
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            scope.node = scope['root'];
+            utils.getScope(scope, 'node').node = scope['root'];
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
-        scope = _origScope10;
+        this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__12__'}));
+        scope = _origScope11;
     }
     return vn1;
 }"
@@ -1316,10 +1336,11 @@ exports[`t-call (template calling recursive template, part 3 2`] = `
     let scope = Object.create(context);
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('div', p2, c2);
     c1.push(vn2);
-    let c3 = [], p3 = {key:3};
+    let c3 = [], p3 = {key:\`\${key0}_3\`};
     let vn3 = h('p', p3, c3);
     c2.push(vn3);
     let _4 = scope['node'].val;
@@ -1335,22 +1356,24 @@ exports[`t-call (template calling recursive template, part 3 2`] = `
     }
     let _length6 = _6.length;
     let _origScope8 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length6; i1++) {
         scope.subtree_first = i1 === 0
         scope.subtree_last = i1 === _length6 - 1
         scope.subtree_index = i1
         scope.subtree = _6[i1]
         scope.subtree_value = _7[i1]
+        let key1 = i1;
         {
             let _origScope9 = scope;
             scope = Object.assign(Object.create(context), scope);
             {
                 let c__0 = [];
-                scope.node = scope['subtree'];
+                utils.getScope(scope, 'node').node = scope['subtree'];
                 scope[utils.zero] = c__0;
             }
-            this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c2, parent: utils.getComponent(context)}));
+            let k10 = \`__10__\${key0}__\${key1}__\`;
+            this.subTemplates['nodeTemplate'].call(this, scope, Object.assign({}, extra, {parentNode: c2, parent: utils.getComponent(context), key: k10}));
             scope = _origScope9;
         }
     }
@@ -1372,10 +1395,10 @@ exports[`t-call (template calling scoped parameters 1`] = `
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            scope.foo = 42;
+            utils.getScope(scope, 'foo').foo = 42;
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__3__'}));
         scope = _origScope2;
     }
     if (scope.foo != null) {
@@ -1395,7 +1418,7 @@ exports[`t-call (template calling t-call with t-if 1`] = `
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
     if (scope['flag']) {
-        this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__3__'}));
     }
     return vn1;
 }"
@@ -1407,7 +1430,8 @@ exports[`t-call (template calling t-call with t-if 2`] = `
     // Template name: \\"sub\\"
     let h = this.h;
     let c1 = extra.parentNode;
-    let c2 = [], p2 = {key:2};
+    let key0 = extra.key || \\"\\";
+    let c2 = [], p2 = {key:\`\${key0}_2\`};
     let vn2 = h('span', p2, c2);
     c1.push(vn2);
     c2.push({text: \`ok\`});
@@ -1432,23 +1456,25 @@ exports[`t-call (template calling t-call with t-set inside and outside 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.v_first = i1 === 0
         scope.v_last = i1 === _length3 - 1
         scope.v_index = i1
         scope.v = _3[i1]
         scope.v_value = _4[i1]
-        scope.val = scope['v'].val;
+        let key1 = i1;
+        utils.getScope(scope, 'val').val = scope['v'].val;
         {
             let _origScope8 = scope;
             scope = Object.assign(Object.create(context), scope);
             {
                 let c__0 = [];
-                scope.val3 = scope.val*3;
+                utils.getScope(scope, 'val3').val3 = scope.val*3;
                 scope[utils.zero] = c__0;
             }
-            this.subTemplates['sub'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+            let k9 = \`__9__\${key1}__\`;
+            this.subTemplates['sub'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: k9}));
             scope = _origScope8;
         }
     }
@@ -1467,7 +1493,7 @@ exports[`t-call (template calling t-call with t-set inside and outside. 2 1`] =
     let c1 = [], p1 = {key:1};
     let vn1 = h('p', p1, c1);
     scope.w = 'fromwrapper';
-    this.subTemplates['main'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['main'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__11__'}));
     return vn1;
 }"
 `;
@@ -1483,19 +1509,19 @@ exports[`t-call (template calling t-call, conditional and t-set in t-call body 1
     let vn1 = h('div', p1, c1);
     scope.v1 = 'elif';
     if (scope.v1==='if') {
-        this.subTemplates['callee1'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['callee1'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__3__'}));
     }
     else if (scope.v1==='elif') {
         {
-            let _origScope5 = scope;
+            let _origScope6 = scope;
             scope = Object.assign(Object.create(context), scope);
             {
                 let c__0 = [];
-                scope.v = 'success';
+                utils.getScope(scope, 'v').v = 'success';
                 scope[utils.zero] = c__0;
             }
-            this.subTemplates['callee2'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
-            scope = _origScope5;
+            this.subTemplates['callee2'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__7__'}));
+            scope = _origScope6;
         }
     }
     return vn1;
@@ -1511,7 +1537,7 @@ exports[`t-call (template calling t-call, global templates 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
-    this.subTemplates['john'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['john'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__3__'}));
     return vn1;
 }"
 `;
@@ -1533,7 +1559,7 @@ exports[`t-call (template calling with unused body 1`] = `
             scope[utils.zero] = c__0;
         }
         result = []
-        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context)}));
+        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context), key: '__4__'}));
         result = result[0]
         scope = _origScope3;
     }
@@ -1554,11 +1580,11 @@ exports[`t-call (template calling with unused setbody 1`] = `
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            scope.qux = 3;
+            utils.getScope(scope, 'qux').qux = 3;
             scope[utils.zero] = c__0;
         }
         result = []
-        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context)}));
+        this.subTemplates['_basic-callee'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context), key: '__4__'}));
         result = result[0]
         scope = _origScope3;
     }
@@ -1583,7 +1609,7 @@ exports[`t-call (template calling with used body 1`] = `
             scope[utils.zero] = c__0;
         }
         result = []
-        this.subTemplates['_callee-printsbody'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context)}));
+        this.subTemplates['_callee-printsbody'].call(this, scope, Object.assign({}, extra, {parentNode: result, parent: utils.getComponent(context), key: '__4__'}));
         result = result[0]
         scope = _origScope3;
     }
@@ -1605,10 +1631,10 @@ exports[`t-call (template calling with used set body 1`] = `
         scope = Object.assign(Object.create(context), scope);
         {
             let c__0 = [];
-            scope.foo = 'ok';
+            utils.getScope(scope, 'foo').foo = 'ok';
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['_callee-uses-foo'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['_callee-uses-foo'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__4__'}));
         scope = _origScope3;
     }
     return vn1;
@@ -1808,7 +1834,7 @@ exports[`t-esc t-esc=0 is escaped 1`] = `
             c4.push({text: \`escaped\`});
             scope[utils.zero] = c__0;
         }
-        this.subTemplates['test'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+        this.subTemplates['test'].call(this, scope, Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__5__'}));
         scope = _origScope3;
     }
     return vn1;
@@ -2096,15 +2122,20 @@ exports[`t-key can use t-key directive on a node 1`] = `
 ) {
     // Template name: \\"test\\"
     let scope = Object.create(context);
+    let result;
     let h = this.h;
-    const nodeKey1 = scope['beer'].id;
-    let c2 = [], p2 = {key:nodeKey1};
-    let vn2 = h('div', p2, c2);
-    let _3 = scope['beer'].name;
-    if (_3 != null) {
-        c2.push({text: _3});
+    {
+        let key0 = scope['beer'].id;
+        let c1 = [], p1 = {key:\`\${key0}_1\`};
+        let vn1 = h('div', p1, c1);
+        result = vn1;
+        result = vn1;
+        let _2 = scope['beer'].name;
+        if (_2 != null) {
+            c1.push({text: _2});
+        }
     }
-    return vn2;
+    return result;
 }"
 `;
 
@@ -2125,20 +2156,20 @@ exports[`t-key t-key directive in a list 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.beer_first = i1 === 0
         scope.beer_last = i1 === _length3 - 1
         scope.beer_index = i1
         scope.beer = _3[i1]
         scope.beer_value = _4[i1]
-        const nodeKey6 = scope['beer'].id;
-        let c7 = [], p7 = {key:nodeKey6};
-        let vn7 = h('li', p7, c7);
-        c1.push(vn7);
-        let _8 = scope['beer'].name;
-        if (_8 != null) {
-            c7.push({text: _8});
+        let key1 = scope['beer'].id;
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
+        let vn6 = h('li', p6, c6);
+        c1.push(vn6);
+        let _7 = scope['beer'].name;
+        if (_7 != null) {
+            c6.push({text: _7});
         }
     }
     scope = _origScope5;
@@ -2229,23 +2260,23 @@ exports[`t-on can bind handlers with loop variable as argument 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.action_first = i1 === 0
         scope.action_last = i1 === _length3 - 1
         scope.action_index = i1
         scope.action = _3[i1]
         scope.action_value = _4[i1]
-        const nodeKey6 = scope['action_index'];
-        let c7 = [], p7 = {key:nodeKey6};
-        let vn7 = h('li', p7, c7);
-        c1.push(vn7);
-        let c8 = [], p8 = {key:nodeKey6,on:{}};
-        let vn8 = h('a', p8, c8);
-        c7.push(vn8);
-        let args9 = [scope['action']];
-        p8.on['click'] = function (e) {if (!context.__owl__.isMounted){return}utils.getComponent(context)['activate'](...args9, e);};
-        c8.push({text: \`link\`});
+        let key1 = scope['action_index'];
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
+        let vn6 = h('li', p6, c6);
+        c1.push(vn6);
+        let c7 = [], p7 = {key:\`\${key1}_7\`,on:{}};
+        let vn7 = h('a', p7, c7);
+        c6.push(vn7);
+        let args8 = [scope['action']];
+        p7.on['click'] = function (e) {if (!context.__owl__.isMounted){return}utils.getComponent(context)['activate'](...args8, e);};
+        c7.push({text: \`link\`});
     }
     scope = _origScope5;
     return vn1;
@@ -2369,7 +2400,8 @@ exports[`t-on t-on with inline statement (function call) 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1,on:{}};
     let vn1 = h('button', p1, c1);
-    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}scope['state'].incrementCounter(2)};
+    const state_2 = scope['state'];
+    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}state_2.incrementCounter(2)};
     c1.push({text: \`Click\`});
     return vn1;
 }"
@@ -2383,7 +2415,8 @@ exports[`t-on t-on with inline statement 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1,on:{}};
     let vn1 = h('button', p1, c1);
-    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}scope['state'].counter++};
+    const state_2 = scope['state'];
+    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}state_2.counter++};
     c1.push({text: \`Click\`});
     return vn1;
 }"
@@ -2397,7 +2430,8 @@ exports[`t-on t-on with inline statement, part 2 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1,on:{}};
     let vn1 = h('button', p1, c1);
-    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}scope['state'].flag=!scope['state'].flag};
+    const state_2 = scope['state'];
+    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}state_2.flag=!state_2.flag};
     c1.push({text: \`Toggle\`});
     return vn1;
 }"
@@ -2411,7 +2445,9 @@ exports[`t-on t-on with inline statement, part 3 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1,on:{}};
     let vn1 = h('button', p1, c1);
-    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}scope['state'].n=scope['someFunction'](3)};
+    const state_2 = scope['state'];
+    const someFunction_2 = scope['someFunction'];
+    p1.on['click'] = function (e) {if (!context.__owl__.isMounted){return}state_2.n=someFunction_2(3)};
     c1.push({text: \`Toggle\`});
     return vn1;
 }"
@@ -2486,24 +2522,27 @@ exports[`t-on t-on with prevent modifier in t-foreach 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.project_first = i1 === 0
         scope.project_last = i1 === _length3 - 1
         scope.project_index = i1
         scope.project = _3[i1]
         scope.project_value = _4[i1]
-        const nodeKey6 = scope['project'];
-        let _7 = '#';
-        let c8 = [], p8 = {key:nodeKey6,attrs:{href: _7},on:{}};
-        let vn8 = h('a', p8, c8);
-        c1.push(vn8);
-        let args9 = [scope['project'].id];
-        p8.on['click'] = function (e) {if (!context.__owl__.isMounted){return}e.preventDefault();utils.getComponent(context)['onEdit'](...args9, e);};
-        c8.push({text: \` Edit \`});
-        let _10 = scope['project'].name;
-        if (_10 != null) {
-            c8.push({text: _10});
+        let key1 = i1;
+        {
+            let key1 = scope['project'];
+            let _6 = '#';
+            let c7 = [], p7 = {key:\`\${key1}_7\`,attrs:{href: _6},on:{}};
+            let vn7 = h('a', p7, c7);
+            c1.push(vn7);
+            let args8 = [scope['project'].id];
+            p7.on['click'] = function (e) {if (!context.__owl__.isMounted){return}e.preventDefault();utils.getComponent(context)['onEdit'](...args8, e);};
+            c7.push({text: \` Edit \`});
+            let _9 = scope['project'].name;
+            if (_9 != null) {
+                c7.push({text: _9});
+            }
         }
     }
     scope = _origScope5;
@@ -2571,7 +2610,7 @@ exports[`t-on t-on with t-call 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
-    this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__4__'}));
     return vn1;
 }"
 `;
@@ -2585,7 +2624,7 @@ exports[`t-on t-on, with arguments and t-call 1`] = `
     let h = this.h;
     let c1 = [], p1 = {key:1};
     let vn1 = h('div', p1, c1);
-    this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context)}));
+    this.subTemplates['sub'].call(this, Object.assign(Object.create(context), scope), Object.assign({}, extra, {parentNode: c1, parent: utils.getComponent(context), key: '__4__'}));
     return vn1;
 }"
 `;
@@ -2729,29 +2768,32 @@ exports[`t-ref refs in a loop 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.item_first = i1 === 0
         scope.item_last = i1 === _length3 - 1
         scope.item_index = i1
         scope.item = _3[i1]
         scope.item_value = _4[i1]
-        const nodeKey6 = scope['item'];
-        let c7 = [], p7 = {key:nodeKey6};
-        let vn7 = h('div', p7, c7);
-        c1.push(vn7);
-        const ref8 = (scope['item']);
-        p7.hook = {
-          create: (_, n) => {
-            context.__owl__.refs[ref8] = n.elm;
-          },
-          destroy: () => {
-            delete context.__owl__.refs[ref8];
-          },
-        };
-        let _9 = scope['item'];
-        if (_9 != null) {
-            c7.push({text: _9});
+        let key1 = i1;
+        {
+            let key1 = scope['item'];
+            let c6 = [], p6 = {key:\`\${key1}_6\`};
+            let vn6 = h('div', p6, c6);
+            c1.push(vn6);
+            const ref7 = (scope['item']);
+            p6.hook = {
+              create: (_, n) => {
+                context.__owl__.refs[ref7] = n.elm;
+              },
+              destroy: () => {
+                delete context.__owl__.refs[ref7];
+              },
+            };
+            let _8 = scope['item'];
+            if (_8 != null) {
+                c6.push({text: _8});
+            }
         }
     }
     scope = _origScope5;
@@ -2953,6 +2995,7 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"test\\"
+    let utils = this.constructor.utils;
     let scope = Object.create(context);
     let h = this.h;
     let c1 = [], p1 = {key:1};
@@ -2967,25 +3010,25 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
     }
     let _length3 = _3.length;
     let _origScope5 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length3; i1++) {
         scope.elem_first = i1 === 0
         scope.elem_last = i1 === _length3 - 1
         scope.elem_index = i1
         scope.elem = _3[i1]
         scope.elem_value = _4[i1]
-        const nodeKey6 = scope['elem_index'];
-        let c7 = [], p7 = {key:nodeKey6};
-        let vn7 = h('div', p7, c7);
-        c1.push(vn7);
-        let c8 = [], p8 = {key:nodeKey6};
-        let vn8 = h('span', p8, c8);
-        c7.push(vn8);
-        c8.push({text: \`v\`});
+        let key1 = scope['elem_index'];
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
+        let vn6 = h('div', p6, c6);
+        c1.push(vn6);
+        let c7 = [], p7 = {key:\`\${key1}_7\`};
+        let vn7 = h('span', p7, c7);
+        c6.push(vn7);
+        c7.push({text: \`v\`});
         if (scope.v != null) {
-            c8.push({text: scope.v});
+            c7.push({text: scope.v});
         }
-        scope.v = scope['elem'];
+        utils.getScope(scope, 'v').v = scope['elem'];
     }
     scope = _origScope5;
     return vn1;

tests/qweb/qweb_expressions.test.ts

@@ -56,6 +56,12 @@ describe("tokenizer", () => {
       { type: "OPERATOR", value: "..." },
       { type: "VALUE", value: "1" }
     ]);
+
+    expect(tokenize("a in b")).toEqual([
+      { type: "SYMBOL", value: "a" },
+      { type: "OPERATOR", value: "in " },
+      { type: "SYMBOL", value: "b" }
+    ]);
   });
 
   test("strings", () => {
@@ -134,6 +140,7 @@ describe("expression evaluation", () => {
     expect(compileExpr("color === 'black'", {})).toBe("scope['color']==='black'");
     expect(compileExpr("'li_'+item", {})).toBe("'li_'+scope['item']");
     expect(compileExpr("state.val > 1", {})).toBe("scope['state'].val>1");
+    expect(compileExpr("a in b", {})).toBe("scope['a']in scope['b']");
   });
 
   test("boolean operations", () => {

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

@@ -11,33 +11,35 @@ exports[`RouteComponent can render simple cases 1`] = `
     let result;
     let h = this.h;
     if (scope['routeComponent']) {
-        const nodeKey4 = scope['env'].router.currentRouteName;
-        // Component 'routeComponent'
-        let k6 = \`__6__\` + nodeKey4;
-        let w5 = k6 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k6]] : false;
-        let vn7 = {};
-        result = vn7;
-        let props5 = Object.assign({}, scope['env'].router.currentParams);
-        if (w5 && w5.__owl__.currentFiber && !w5.__owl__.vnode) {
-            w5.destroy();
-            w5 = false;
+        {
+            let key0 = scope['env'].router.currentRouteName;
+            // Component 'routeComponent'
+            let k5 = \`__5__\${key0}__\`;
+            let w4 = k5 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k5]] : false;
+            let vn6 = {};
+            result = vn6;
+            let props4 = Object.assign({}, scope['env'].router.currentParams);
+            if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
+                w4.destroy();
+                w4 = false;
+            }
+            if (w4) {
+                w4.__updateProps(props4, extra.fiber, undefined);
+                let pvnode = w4.__owl__.pvnode;
+                utils.defineProxy(vn6, pvnode);
+            } else {
+                let componentKey4 = \`routeComponent\`;
+                let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| scope['routeComponent'];
+                if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
+                w4 = new W4(parent, props4);
+                parent.__owl__.cmap[k5] = w4.__owl__.id;
+                let fiber = w4.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+                let pvnode = h('dummy', {key: k5, hook: {remove() {},destroy(vn) {w4.destroy();}}});
+                utils.defineProxy(vn6, pvnode);
+                w4.__owl__.pvnode = pvnode;
+            }
+            w4.__owl__.parentLastFiberId = extra.fiber.id;
         }
-        if (w5) {
-            w5.__updateProps(props5, extra.fiber, undefined);
-            let pvnode = w5.__owl__.pvnode;
-            utils.defineProxy(vn7, pvnode);
-        } else {
-            let componentKey5 = \`routeComponent\`;
-            let W5 = context.constructor.components[componentKey5] || QWeb.components[componentKey5]|| scope['routeComponent'];
-            if (!W5) {throw new Error('Cannot find the definition of component \\"' + componentKey5 + '\\"')}
-            w5 = new W5(parent, props5);
-            parent.__owl__.cmap[k6] = w5.__owl__.id;
-            let fiber = w5.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k6, hook: {remove() {},destroy(vn) {w5.destroy();}}});
-            utils.defineProxy(vn7, pvnode);
-            w5.__owl__.pvnode = pvnode;
-        }
-        w5.__owl__.parentLastFiberId = extra.fiber.id;
     }
     return result;
 }"

tests/store_hooks.test.ts

@@ -49,10 +49,13 @@ describe("connecting a component to store", () => {
   });
 
   test("useStore can observe primitive types and call onUpdate", async () => {
-    const state = { isBoolean: false };
+    const state = { isBoolean: false, nullValue: null };
     const actions = {
       setTrue({ state }) {
         state.isBoolean = true;
+      },
+      setNotNull({ state }) {
+        state.nullValue = "ok";
       }
     };
     const store = new Store({ state, actions });
@@ -61,8 +64,10 @@ describe("connecting a component to store", () => {
       static template = xml`
             <div>
                 <span t-if="isBoolean">ok</span>
+                <span t-if="nullValue !== null">not null</span>
             </div>`;
       isBoolean: boolean;
+      nullValue: string;
       constructor() {
         super();
         this.isBoolean = useStore(state => state.isBoolean, {
@@ -70,6 +75,11 @@ describe("connecting a component to store", () => {
             this.isBoolean = isBoolean;
           }
         });
+        this.nullValue = useStore(state => state.nullValue, {
+          onUpdate: nullValue => {
+            this.nullValue = nullValue;
+          }
+        });
       }
     }
 
@@ -82,6 +92,10 @@ describe("connecting a component to store", () => {
     store.dispatch("setTrue");
     await nextTick();
     expect(fixture.innerHTML).toBe("<div><span>ok</span></div>");
+
+    store.dispatch("setNotNull");
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>ok</span><span>not null</span></div>");
   });
 
   test("map works on the result of useStore when the resulting array changes for a bigger one", async () => {

tests/tooling/debug_script_4.test.ts

@@ -0,0 +1,57 @@
+/**
+ * We can only make one test per file, since the debug tool modify in place
+ * the owl object in a way that is difficult to undo.
+ */
+
+import { debugOwl } from "../../tools/debug";
+import * as owl from "../../src/index";
+
+import { Component, Env } from "../../src/component/component";
+import { xml } from "../../src/tags";
+import { makeTestFixture, makeTestEnv } from "../helpers";
+
+let fixture: HTMLElement = makeTestFixture();
+let env: Env = makeTestEnv();
+Component.env = env;
+
+debugOwl(owl, { logScheduler: true });
+
+test("log a sub component with non stringifiable props", async () => {
+  const steps: string[] = [];
+  const log = console.log;
+  console.log = arg => steps.push(arg);
+
+  class Child extends Component<any, any> {
+    static template = xml`<span><t t-esc="props.obj.val"/></span>`;
+  }
+
+  const circularObject: any = { val: 1 };
+  circularObject.circularObject = circularObject;
+
+  class Parent extends Component<any, any> {
+    static template = xml`<div><Child obj="obj"/></div>`;
+    static components = { Child };
+    obj = circularObject;
+  }
+
+  const parent = new Parent(null, {});
+  await parent.mount(fixture);
+  parent.unmount();
+
+  expect(steps).toEqual([
+    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
+    "[OWL_DEBUG] Parent<id=1> mount",
+    "[OWL_DEBUG] Parent<id=1> willStart",
+    "[OWL_DEBUG] scheduler: start running tasks queue",
+    "[OWL_DEBUG] Parent<id=1> rendering template",
+    "[OWL_DEBUG] Child<id=2> constructor, props=<JSON error>",
+    "[OWL_DEBUG] Child<id=2> willStart",
+    "[OWL_DEBUG] Child<id=2> rendering template",
+    "[OWL_DEBUG] Child<id=2> mounted",
+    "[OWL_DEBUG] Parent<id=1> mounted",
+    "[OWL_DEBUG] scheduler: stop running tasks queue",
+    "[OWL_DEBUG] Parent<id=1> willUnmount",
+    "[OWL_DEBUG] Child<id=2> willUnmount"
+  ]);
+  console.log = log;
+});

tools/debug.js

@@ -35,7 +35,12 @@
   });
 
   function toStr(obj) {
-    let str = JSON.stringify(obj || {});
+    let str;
+    try {
+      str = JSON.stringify(obj || {});
+    } catch (e) {
+      str = "<JSON error>";
+    }
     if (str.length > 200) {
       str = str.slice(0, 200) + "...";
     }

tools/playground/samples.js

@@ -455,7 +455,7 @@ const actions = {
         todo.completed = !todo.completed;
     },
     clearCompleted({ state, dispatch }) {
-        for (let todo of state.todos) {
+        for (let todo of state.todos.slice()) {
             if (todo.completed) {
                 dispatch("removeTodo", todo.id);
             }
@@ -1089,20 +1089,20 @@ const RESPONSIVE_XML = `<templates>
     <button>Button!</button>
   </div>
 
+  <t t-name="maincontent">
+    <FormView />
+    <Chatter />
+  </t>
   <div t-name="App" class="app" t-att-class="{mobile: env.isMobile, desktop: !env.isMobile}">
-    <t t-set="maincontent">
-      <FormView />
-      <Chatter />
-    </t>
     <Navbar/>
     <ControlPanel/>
     <div class="content-wrapper" t-if="!env.isMobile">
       <div class="content">
-        <t t-raw="maincontent"/>
+        <t t-call="maincontent"/>
       </div>
     </div>
     <t t-else="">
-      <t t-raw="maincontent"/>
+      <t t-call="maincontent"/>
     </t>
   </div>
 </templates>

tsconfig.json

@@ -13,7 +13,8 @@
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
     "strictPropertyInitialization": true,
-    "strictNullChecks": true
+    "strictNullChecks": true,
+    "declarationDir": "dist/types"
   },
   "include": ["src/**/*.ts","src/*.ts"]
 }