This commit introduces an interface for `toSignal` options to mirror that of
`toObservable`, and adjusts docs for both symbols. It also adds the ability
for `toSignal` to manually specify `DestroyRef` (similarly to
`toObservable` accepting an injector) or for `toSignal` automatic cleanup to
be disabled (in which case the subscription persists until the Observable
completes). Either option allows `toSignal` to be used outside of a DI
context, like `toObservable`.
PR Close#50071
As described in
https://github.com/angular/angular/discussions/49681#discussioncomment-5628930,
if an `Observable` created from a signal with `toObservable` is
subscribed to in a template, it will initially have `null` as the value.
Immediately after the template is done executing, effects are flushed
and this results in the `AsyncPipe` getting a new value before the
`checkNoChanges` pass, resulting in `ExpressionChanged` error.
```
template: '{{obs$ | async}}'
...
obs$ = toObservable(signal(0));
```
Instead, this commit updates the `toObservable` to synchronously emit
the initial value to the Observable stream.
Side note here: We don't exactly encourage this pattern. Instead of
using `AsyncPipe`, the template should just read signals.
PR Close#49894
The initial value used for signals by default is now `undefined`. In
addition, there is a new option to express that the signal should emit a
value synchronously (`requireSync: true`). When this value is specified,
the function will throw _on creation_ if the subscribing to the
`Observable` does not result in a synchronous emit.
PR Close#49769
The change in effect timing collided with the introduction of these
rxjs-interop tests, resulting in them failing after the merge.
This commit adjusts the tests to rely on the real effect timing.
PR Close#49651
This commit implements an RxJS operator `takeUntilDestroyed` which
terminates an Observable when the current context (component, directive,
etc) is destroyed. `takeUntilDestroyed` will inject the current `DestroyRef`
if none is provided, or use one provided as an argument.
PR Close#49154
This commit adds the basic sketch for the implementation of `fromObservable`
and `fromSignal`, the two basic primitives which form the RxJS interop layer
with signals.
PR Close#49154
Alex Rickabaugh