Comments (3)
It will be unfortunate if subscribe
is async again. One of the issues I had with the two methods is then how should connect
work on a ConnectableObservable
(The result of a multicast)? I realize this proposal isn't RxJS, but a connectable observable or a "hot" observable seems like an inevitability. Would there need to be a connectSync and a connectAsync?
a subscribeOn
is just a lot more flexible. FWIW, it seems like JavaScript should have native schedulers, because it's silly people keep reinventing microtask polyfills. That would be a whole different ball of wax, though.
from es-observable.
I think async subscription is not intuitive for the general case. If I say "subscribe", I expect to receive any event which happens from the time "subscribe" returns onward. That's the crux of the EventTarget problem. In my opinion, this problem is general in scope: the issue will arise whenever we want to model events which are not buffered.
The goal of avoiding zalgo is good, though, and we should take it seriously.
Having two methods solves one problem, but it creates another: how is the non-expert developer supposed to know which is appropriate? The difference is too subtle, and I would rather this thing "just work" without having to explain such subtleties.
The ideal, for me, is a universe where subscription is always sync, but observables never deliver data before "subscribe" has completed. That's why I have Observable.of
delivering its arguments in a job rather than synchronously.
Unfortunately, I was unable to come up with an API which would elegantly enforce such a limitation. In the end, I was content with core API not enforcing any such restriction, and instead relying on best-practices to emerge among users (with the help of the good example set by Observable.of
).
Javascript is definitely missing an enqueueJob
primitive though.
At the end of the day, the zalgo problem might not even matter that much. If observables are ultimately compatible with async iteration statements, then users can "subscribe" to an observable like this:
for await (let x of someObservable) {
// Do whatever with `x`
}
Since control flow doesn't get split into sync and async paths, there is no zalgo to worry about.
from es-observable.
Closing due to inactivity (and I'm still opposed to two subscription methods in the core proposal).
from es-observable.
Related Issues (20)
- Invalid test based on Interface. HOT 1
- `obs.subscribe(next, error, complete)` should bind their callbacks to `undefined` when present HOT 5
- Why does `Observable.prototype.subscribe` report thrown errors from `observer.start(sub)` asynchronously instead of just propagating them?
- Minor spec bug WRT cleanup in `subscribe`
- `Observable.from` iteration functions incorrectly assume their observer parameter is native HOT 1
- [ALTERNATIVE] Proposal for an alternative
- Cleanup function should be passed to the SubscriptionObserver
- Simplification of Observable API HOT 69
- End a subscription if a completion token is returned HOT 1
- Even simpler API HOT 4
- Reduced API with async/await support HOT 23
- Observable should be async HOT 5
- Syntax Support HOT 4
- Alternative: Pub/Sub
- Moving to an API with AbortSignal HOT 9
- Retain core API and leave operators to user-land libraries HOT 15
- Permit unsubscribe to return a promise HOT 3
- Is there any update? HOT 34
- Support [Symbol.dispose]() for unsubscribe() HOT 1
- Unsubscribe
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