32 lines
2.3 KiB
TypeScript
32 lines
2.3 KiB
TypeScript
|
import { Observable } from '../Observable';
|
||
|
|
import { Unsubscribable, ObservableInput } from '../types';
|
||
|
|
/**
|
||
|
|
* Creates an Observable that uses a resource which will be disposed at the same time as the Observable.
|
||
|
|
*
|
||
|
|
* <span class="informal">Use it when you catch yourself cleaning up after an Observable.</span>
|
||
|
|
*
|
||
|
|
* `using` is a factory operator, which accepts two functions. First function returns a disposable resource.
|
||
|
|
* It can be an arbitrary object that implements `unsubscribe` method. Second function will be injected with
|
||
|
|
* that object and should return an Observable. That Observable can use resource object during its execution.
|
||
|
|
* Both functions passed to `using` will be called every time someone subscribes - neither an Observable nor
|
||
|
|
* resource object will be shared in any way between subscriptions.
|
||
|
|
*
|
||
|
|
* When Observable returned by `using` is subscribed, Observable returned from the second function will be subscribed
|
||
|
|
* as well. All its notifications (nexted values, completion and error events) will be emitted unchanged by the output
|
||
|
|
* Observable. If however someone unsubscribes from the Observable or source Observable completes or errors by itself,
|
||
|
|
* the `unsubscribe` method on resource object will be called. This can be used to do any necessary clean up, which
|
||
|
|
* otherwise would have to be handled by hand. Note that complete or error notifications are not emitted when someone
|
||
|
|
* cancels subscription to an Observable via `unsubscribe`, so `using` can be used as a hook, allowing you to make
|
||
|
|
* sure that all resources which need to exist during an Observable execution will be disposed at appropriate time.
|
||
|
|
*
|
||
|
|
* @see {@link defer}
|
||
|
|
*
|
||
|
|
* @param {function(): ISubscription} resourceFactory A function which creates any resource object
|
||
|
|
* that implements `unsubscribe` method.
|
||
|
|
* @param {function(resource: ISubscription): Observable<T>} observableFactory A function which
|
||
|
|
* creates an Observable, that can use injected resource object.
|
||
|
|
* @return {Observable<T>} An Observable that behaves the same as Observable returned by `observableFactory`, but
|
||
|
|
* which - when completed, errored or unsubscribed - will also call `unsubscribe` on created resource object.
|
||
|
|
*/
|
||
|
|
export declare function using<T>(resourceFactory: () => Unsubscribable | void, observableFactory: (resource: Unsubscribable | void) => ObservableInput<T> | void): Observable<T>;
|