[IMP] misc: export the validate function

The props validation code is actually quite difficult to get right.
Also, it is sometimes useful to be able to validate an object against a
specified schema. Therefore, this commit exports the standalone validate
function as an utility function.

doc/readme.md

@@ -45,4 +45,5 @@ Utility/helpers:
 - [`loadFile`](reference/utils.md#loadfile): an helper to load a file from the server
 - [`markup`](reference/templates.md#outputting-data): utility function to define strings that represent html (should not be escaped)
 - [`status`](reference/component.md#status-helper): utility function to get the status of a component (new, mounted or destroyed)
+- [`validate`](reference/utils.md#validate): validates if an object satisfies a specified schema
 - [`whenReady`](reference/utils.md#whenready): utility function to execute code when DOM is ready

doc/reference/props.md

@@ -243,6 +243,8 @@ class ComponentB extends owl.Component {
   };
 ```
 
+Note: the props validation code is done by using the [validate utility function](utils.md#validate).
+
 ## Good Practices
 
 A `props` object is a collection of values that come from the parent. As such,

doc/reference/utils.md

@@ -8,6 +8,7 @@ functions are all available in the `owl.utils` namespace.
 - [`whenReady`](#whenready): executing code when DOM is ready
 - [`loadFile`](#loadfile): loading a file (useful for templates)
 - [`EventBus`](#eventbus): a simple EventBus
+- [`validate`](#validate): a validation function
 
 ## `whenReady`
 
@@ -56,3 +57,24 @@ bus.addEventListener("event", () => console.log("something happened"));
 
 bus.trigger("event"); // 'something happened' is logged
 ```
+
+## `validate`
+
+The `validate` function is a function that validates if a given object satisfies a
+specified schema. It is actually used by Owl itself to perform
+[props validation](props.md#props-validation). For example:
+
+```js
+validate(
+  { a: "hey" },
+  {
+    id: Number,
+    url: [Boolean, { type: Array, element: Number }],
+  }
+);
+
+// throws an error with the following information:
+//    - unknown key 'a',
+//    - 'id' is missing (should be a number),
+//    - 'url' is missing (should be a boolean or list of numbers),
+```

src/index.ts

@@ -52,5 +52,6 @@ export {
   onWillDestroy,
   onError,
 } from "./component/lifecycle_hooks";
+export { validate } from "./validation";
 
 export const __info__ = {};