[DOC] update changelog

CHANGELOG.md

@@ -10,11 +10,13 @@ removed after.
 
 ## Changes
 
+All changes are documented here in no particular order.
+
 **Components**
 
 - components can now have empty content or multiple root nodes (htmlelement or text) ([details](#31-components-can-now-have-arbitrary-content))
-- new `useEffect` hook
-- new `onDestroyed`, `onWillRender` and `onRendered` hooks
+- new `useEffect` hook ([doc](doc/reference/hooks.md#useeffect))
+- new `onDestroyed`, `onWillRender` and `onRendered` hooks ([doc](doc/reference/component.md#lifecycle))
 - breaking: lifecycle methods are removed ([details](#1-component-lifecycle-methods-are-removed))
 - breaking: can no longer be mounted on detached DOM ([details](#2-components-can-no-longer-be-mounted-in-a-detached-dom-element))
 - breaking: standalone `mount` method API is simpler ([details](#4-mount-method-api-is-simpler))
@@ -22,14 +24,18 @@ removed after.
 - breaking: components can no longer be unmounted/remounted ([details](#6-components-can-no-longer-be-unmountedremounted))
 - breaking: template name is no longer inferred from the class name ([details](#7-template-name-is-no-longer-inferred-from-the-class-name))
 - breaking: components no longer have a `shouldUpdate` method ([details](#8-components-no-longer-have-a-shouldupdate-method))
-- breaking: component.el may be a text node, and is no longer `null` ([details](#9-componentel-may-be-a-text-node-and-is-no-longer-null))
+- breaking: component.el is removed ([details](#9-componentel-is-removed))
 - breaking: style/class on components are now regular props ([details](#10-styleclass-on-components-are-now-regular-props))
 - breaking: components can no longer be mounted with position=self ([details](#11-components-can-no-longer-be-mounted-with-positionself))
 - breaking: `t-on` does not work on components any more ([details](#12-t-on-does-not-work-on-components-any-more))
 - breaking: `t-component` no longer accepts strings ([details](#17-t-component-no-longer-accepts-strings))
+- breaking: `render` method does not return a promise anymore ([details](#35-render-method-does-not-return-a-promise-anymore))
+- breaking: `catchError` method is replaced by `onError` hook ([details](#36-catcherror-method-is-replaced-by-onerror-hook))
+
 
 **Portal**
 
+- Portal are now defined with `t-portal` ([details](#33-portal-are-now-defined-with-t-portal))
 - portals can now have arbitrary content (no longer restricted to one single child)
 - breaking: does no longer transfer dom events ([details](#13-portal-does-no-longer-transfer-dom-events))
 - breaking: does render as an empty text node instead of `<portal/>` ([details](#14-portal-does-render-as-an-empty-text-node-instead-of-portal))
@@ -37,6 +43,10 @@ removed after.
 **Slots**
 
 - breaking: `t-set` does not define a slot any more ([details](#3-t-set-will-no-longer-work-to-define-a-slot))
+- slots capabilities have been improved ([doc](doc/reference/slots.md))
+  - params can be give to slot content (to pass information from slot owner to slot user)
+  - slots are given as a `prop` (and can be manipulated/propagated to sub components )
+  - slots can define scopes (to pass information from slot user to slot owner)
 
 **Miscellaneous**
 
@@ -46,6 +56,7 @@ removed after.
 - finer grained reactivity: sub components can reobserve state
 - new App class to encapsulate a root Owl component (with the config for that application)
 - new `Memo` component
+- new [`useEffect`](doc/reference/hooks.md#useeffect) hook
 - breaking: `Context` is removed ([details](#15-context-is-removed))
 - breaking: `env` is now totally empty ([details](#16-env-is-now-totally-empty))
 - breaking: most exports are exported at top level ([details](#18-most-exports-are-exported-at-top-level))
@@ -62,7 +73,7 @@ removed after.
 - breaking: `t-ref` does not work on components ([details](#29-t-ref-does-not-work-on-component))
 - breaking: `t-on` does not accept expressions, only functions ([details](#30-t-on-does-not-accept-expressions-only-functions))
 - breaking: `renderToString` function on qweb has been removed ([details](#32-rendertostring-on-qweb-has-been-removed))
-
+- breaking: `debounce` utility function has been removed ([details](#34-debounce-utility-function-has-been-removed))
 
 ## Details/Rationale/Migration
 
@@ -96,6 +107,8 @@ class MyComponent extends Component {
 }
 ```
 
+Documentation: [Component Lifecycle](doc/reference/component.md#lifecycle)
+
 ### 2. components can no longer be mounted in a detached dom element
 
 Nor document fragment.
@@ -147,6 +160,8 @@ because real applications will need to configure the templates, the translations
 and other stuff. All complex usecases need to go through the new `App` class,
 that encapsulates the root of an owl application.
 
+Documentation: [Mounting a component](doc/reference/app.md#mount-helper)
+
 ### 5. components can no longer be instantiated and mounted by hand
 
 In Owl 1, it was possible to instantiate a component by hand:
@@ -240,10 +255,14 @@ ideas may help:
     </Memo>
   ```
 
-### 9. component.el may be a text node, and is no longer `null`
+### 9. component.el is removed
 
-This comes from the fact that Owl 2 supports fragments (arbitrary content). When
-it is not defined, it was `null` in Owl 1 and is `undefined` in owl 2.
+This comes from the fact that Owl 2 supports fragments (arbitrary content).
+
+Migration: if one need a reference to the root htmlelement of a template, it is
+suggested to simply add a `ref` on it, and access the reference as needed.
+
+Documentation: [Refs](doc/reference/refs.md)
 
 ### 10. style/class on components are now regular props
 
@@ -286,7 +305,13 @@ compatible with the fact that a component can have a root `<div>` then later,
 change it to something else, or even a text node.
 
 Migration: no real way to do the same. Owl application needs to be appended or
-prepended in something, maybe a `div`.
+prepended in something, maybe a `div`. Remember that you the root component
+can have multiple roots
+
+Documentation:
+- [Fragments](doc/reference/templates.md#fragments)
+- [Mounting a component](doc/reference/app.md#mount-helper)
+
 
 ### 12. `t-on` does not work on components any more
 
@@ -372,6 +397,8 @@ Migration: there is no proper way to get an equivalent. The closest is to get
 a reference to the root App using `this.__owl__.app`. If you need to do this,
 let us know. If this is a legitimate usecase, we may add a `useApp` hook.
 
+Documentation: [Environment](doc/reference/environment.md)
+
 ### 17. `t-component` no longer accepts strings
 
 In owl 1, we could write this:
@@ -397,6 +424,8 @@ the implementation is slightly simpler.
 Migration: simply using `constructor.components.Coucou` instead of `Coucou` will
 do the trick.
 
+Documentation: [Component](doc/reference/component.md#dynamic-sub-components)
+
 ### 18. most exports are exported at top level
 
 Most exports are flattened: for ex, `onMounted` is in owl, not in `owl.hooks`.
@@ -453,6 +482,8 @@ rewritten like this: `bus.addEventListener("event-type", (({detail: info}) => {.
 
 Do not forget to similarly replace `bus.off(...)` by `bus.removeEventListener(...)`
 
+Documentation: [EventBus](doc/reference/utils.md#eventbus)
+
 ### 22. `Store` is removed
 
 The Store system had been abandoned in owl 2.
@@ -522,6 +553,7 @@ AND the component. It now only defines an environment for the children.
 Rationale: This was a subtle cause for bugs: some code had to be rrun
 before the call to `useSubEnv`, otherwise it could interfere with the sub environment.
 
+Documentation: [Hooks](doc/reference/hooks.md#usesubenv)
 
 ### 28. `env` is now frozen
 
@@ -536,6 +568,8 @@ components. This use case still works with `useSubEnv`.
 Migration: use `useSubEnv` instead of writing directly to the env.  Also, note
 that the environment given to the App can initially contain anything.
 
+Documentation: [Environment](doc/reference/environment.md)
+
 ### 29. `t-ref` does not work on component
 
 Before, `t-ref` could be used to get a reference to a child component. It no
@@ -576,6 +610,8 @@ adapted like this:
 <button t-on-click="() => this.someFunction(someVar)">blabla</button>
 ```
 
+Documentation: [Event Handling](doc/reference/event_handling.md)
+
 ### 31. components can now have arbitrary content
 
 Before Owl 2, components had to limit themselves to one single htmlelement as
@@ -588,6 +624,8 @@ So, the following template works for components:
   hello
 ```
 
+Documentation: [Fragments](doc/reference/templates.md#fragments)
+
 ### 32. `renderToString` on QWeb has been removed
 
 Rationale: the `renderToString` function was a qweb method, which made sense because
@@ -609,4 +647,55 @@ export async function renderToString(template, context) {
   app.destroy();
   div.remove();
   return result;
-}
+}
+```
+
+### 33. Portal are now defined with `t-portal`
+
+Before Owl 2, one could use the `Portal` component by importing it and using it.
+Now, it is no longer available. Instead, we can simply use the `t-portal` directive:
+
+```xml
+<div>
+  some content
+  <span t-portal="'body'">
+    portalled content
+  </span>
+<div>
+```
+
+Rationale: it makes it slightly simpler to use (just need the directive, instead
+of having to import and use a sub component), it makes the implementation slightly
+simpler as well. Also, it prevents subclassing the Portal component, which could
+be dangerous, since it is really doing weird stuff under the hood, and could
+easily be broken inadvertendly.
+
+### 34. `debounce` utility function has been removed
+
+Rationale: it did not really help that much, is available as utility function
+elsewhere, so, we decided to have a smaller footprint by focusing Owl on what
+it does best.
+
+### 35. `render` method does not return a promise anymore
+
+Rationale: using the `render` method directly and waiting for it to complete
+was slightly un-declarative. Also, it can be done using the lifecycle hooks
+any way.
+
+Migration: if necessary, one can use the lifecycle hooks to execute code after
+the next mounted/patched operation.
+
+### 36. `catchError` method is replaced by `onError` hook
+
+The `catchError` method was used to provide a way to components to handle errors
+occurring during the component lifecycle. This has been replaced by a `onError`
+hook, with a similar API.
+
+Rationale: `catchError` felt a little big awkward, when most of the way we
+interact with componentss is via hooks.  Using hooks felt more natural and
+consistent.
+
+Migration: mostly replace all `catchError` methods by `onError` hooks in the
+`setup` method.
+
+Documentation: [Error Handling](doc/reference/error_handling.md)