refactor(combineLatest): Improve types #5847
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benlesh
commented
Oct 22, 2020
benlesh
commented
- Reduces some type complexity in combineLatest
- Improves types around resultSelectors
- Reduces some type complexity in combineLatest - Improves types around result selectors
cartant
requested changes
Oct 22, 2020
| @@ -37,31 +37,31 @@ it('should accept union types', () => { | |||
| }); | |||
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| it('should accept 1 param and a result selector', () => { | |||
| const o = combineLatest(a$, () => new A()); // $ExpectType Observable<A> | |||
| const o = combineLatest(a$, (a) => new A()); // $ExpectType Observable<A> | |||
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nitpick: Specifying the parameter here does nothing, ATM, but we could improve the tests by using them:
const o = combineLatest(a$, (a) => [a] as const); // $ExpectType Observable<[A]>| >( | ||
| sources: [O1, O2, O3, O4, O5, O6], | ||
| export function combineLatest<A extends readonly unknown[], R>( | ||
| sources: readonly [...ObservableInputTuple<A>], |
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issue: R is not used in this sig. The return type should be Observable<A>, AFAICT.
nitpick: Why is the surrounding [... ] needed? Why not sources: ObservableInputTuple<A>? This occurs elsewhere, too.
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Having used this, I can see, now, that the [... ] business is needed.
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| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<T, R>(source: ObservableInput<T>, resultSelector: (value: T) => R, scheduler?: SchedulerLike): Observable<R>; | ||
| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<T>(source: ObservableInput<T>, scheduler: SchedulerLike): Observable<[T]>; | ||
| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<T>(source: ObservableInput<T>): Observable<[T]>; | ||
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| /** @deprecated Passing a scheduler here is deprecated, use {@link subscribeOn} and/or {@link observeOn} instead */ | ||
| export function combineLatest<R>( | ||
| ...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R) | SchedulerLike> | ||
| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<A extends readonly unknown[], R>(...sources: [...ObservableInputTuple<A>, (...args: A) => R]): Observable<R>; | ||
| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<A extends readonly unknown[], R>( | ||
| ...sources: [...ObservableInputTuple<A>, (...args: A) => R, SchedulerLike] | ||
| ): Observable<R>; | ||
| /** @deprecated Use the version that takes an array of Observables instead */ | ||
| export function combineLatest<A extends readonly unknown[]>(...sources: [...ObservableInputTuple<A>, SchedulerLike]): Observable<A>; |
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question: Why does this use an approach that differs from what's done with merge? Does this behave a little better? Are there tests to show this?
kolodny
approved these changes
Oct 27, 2020
| >( | ||
| sources: [O1, O2, O3, O4, O5, O6], | ||
| export function combineLatest<A extends readonly unknown[], R>( | ||
| sources: readonly [...ObservableInputTuple<A>], |
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OOO is readonly needed here? Doesn't make a difference IMO, purely curious
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Closing this 'cause the |
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