Deprecating CompositeObservable in favor of Subjects about rxjavafx

[rguillens]

I understand what you mean, a workaround could be subscribing with method references:

Subject subject = ...
Disposable disposable = myEventsObservable.subscribe(subject::onNext, subject::onError, subject::onComplete);

[rguillens]

I've tested different scenarios, and I can say Subject is a most straight forward solution than CompositeObservable. I'm just re-thinking about all common scenarios involving concurrency , although ideally CompositeObservable should be used to listen UI events from other layer, as events are always produced on JavaFx Application Thread, theorically there should be no problem.

[thomasnield]

Yes those were kind of my thoughts. I have thought about making an FXSubject that would handle serialization and observing on the FX thread. I havent entirely dismissed that idea but in a great majority of cases, emissions going in and out should already be on the FX thread anyway. I can see occasional situations it might be useful though...

[thomasnield]

I have found a potentially serious issue: subscribing a subject does not return a Disposable.

[rguillens]

Explain this issue a little more. The only subscribe implementation that doesn't return a Disposable in Observable is public final void subscribe(io.reactivex.Observer<? super T> observer) and all Subjects inherit this method.

[thomasnield]

I'll post a better example tomorrow, but...

Subject subject = ...
myEventsObservable.subscribe(subject); // Does not return Disposable

[thomasnield]

Yup, good thought. I looked at my implementation of CompositeObservable and that is exactly what I did.

https://github.com/ReactiveX/RxJavaFX/blob/2.x/src/main/java/io/reactivex/rxjavafx/sources/CompositeObservable.java

I'm a tad unsure what to do here... whether to tell users to do that subscribe() trick themselves, implement a new utility, or keep things as is.

Too bad Java doesn't have extension functions like Kotlin. Those would be pretty handy for this problem right now...

[thomasnield]

I wonder if its possible creating a Subject implementation that does all this, and can have a dispose() method on it.

[thomasnield]

I think I'm going to deprecate. I see @akarnokd gave a thumbs up to the subject route, so that's enough to push me out of my quandary.