## Inheritance Semantics:
Decorators:
1) list the decorators of the class and its parents in the ancestor first order
2) only use the last decorator of each kind (e.g. @Component / ...)
Constructor parameters:
If a class inherits from a parent class and does not declare
a constructor, it inherits the parent class constructor,
and with it the parameter metadata of that parent class.
Lifecycle hooks:
Follow the normal class inheritance model,
i.e. lifecycle hooks of parent classes will be called
even if the method is not overwritten in the child class.
## Example
E.g. the following is a valid use of inheritance and it will
also inherit all metadata:
```
@Directive({selector: 'someDir'})
class ParentDirective {
constructor(someDep: SomeDep) {}
ngOnInit() {}
}
class ChildDirective extends ParentDirective {}
```
Closes#11606Closes#12892
This is needed to resolve symbols without `.d.ts` files.
This bumps the version of the metadata from 1 to 2.
This adds logic into `ng_host.ts` to automatically upgrade
version 1 to version 2 metadata by adding the exported symbols
from the `.d.ts` file.
Add support for the `$postDigest()` and `$onDestroy()` lifecycle hooks.
Better align the behavior of the `$onChanges()` and `$onInit()` lifecycle hooks
with Angular 1.x:
- Call `$onInit()` before pre-linking.
- Always instantiate the controller before calling `$onChanges()`.
Add upgrade-static.umd.js bundles
This allows depending on it without getting a transitive dependency on compiler.
BREAKING CHANGE:
Four newly added APIs in 2.2.0-beta:
downgradeComponent, downgradeInjectable, UpgradeComponent, and UpgradeModule
are no longer exported by @angular/upgrade.
Import these from @angular/upgrade/static instead.
This commit introduces a new API to the ngUpgrade module, which is compatible
with AoT compilation. Primarily, it removes the dependency on reflection
over the Angular 2 metadata by introducing an API where this information
is explicitly defined, in the source code, in a way that is not lost through
AoT compilation.
This commit is a collaboration between @mhevery (who provided the original
design of the API); @gkalpak & @petebacondarwin (who implemented the
API and migrated the specs from the original ngUpgrade tests) and @alexeagle
(who provided input and review).
This commit is an starting point, there is still work to be done:
* add more documentation
* validate the API via internal projects
* align the ngUpgrade compilation of A1 directives closer to the real A1
compiler
* add more unit tests
* consider support for async `templateUrl` A1 upgraded components
Closes#12239