Bind observable to collection of observers

[sgtsquiggs]

Name and description

An extension on ObservableType to allow .bind(to:) with a collection of observers, and an extension on Collection (where Iterator.Element == Disposable) to allow .disposed(by:) with a collection of Disposables.

Motivation for inclusion

Useful when you have a single observable binding to a lot of observers. A big use case is when implementing forms and having a single observable bind to isEnabled on a multitude of controls.

Example of use

isEnabledSubject
  .bind(to: myCollectionOfTextFields.map({$0.rx.isEnabled}))
  .disposed(by: disposeBag)

Implementation here: https://gist.github.com/sgtsquiggs/0b1dc9dbd6fe51f107d4082ac7c448cd

[freak4pc]

Uhm this is actually very interesting :)
Let me ponder on this a bit - I think there are a few issues with this, as it requires creating collections of ObserverType(s)/Relays to bind into, which might be a bit niche but useful when creating these sorts of validations (e.g. many things are affected by a single value).

Still could be possibly useful. Any feedback from @RxSwiftCommunity/contributors would be super-helpful here.

The overload of disposing many Disposable(s) together might also be useful in general - But might be better to use CompositeDisposable for that, as it has proper locking etc?

[jegnux]

I agree with @freak4pc
It's a an interesting addition, but we should indeed use CompositeDisposable instead. It even simplifies the implementation to only that:

extension ObservableType {
    func bind<O>(to observers: [O]) -> Disposable where O : ObserverType, Self.E == O.E {
        let shared = self.share()
        let disposables = observers.map(shared.bind(to:))
        return CompositeDisposable(disposables: disposables)
    }
}

[valerianb]

There was recently a PR on RxSwift to take care of disposables in one call:
ReactiveX/RxSwift#1676

[sgtsquiggs]

Oh I wasn't aware of CompositeDisposable. I'll update my gist!

[freak4pc]

@valerianb that is also a cool PR (the .bag one) but doesn't solve the same thing exactly IMO.

You would still need to repeat the binding (a.bind(to: b), a.bind(to:c)), instead of a.bind(to: [b, c])). So when thinking about this the last few days I think this could be a great addition if you'd like to build it @sgtsquiggs and push a PR so I can review, with tests, etc.

[M0rtyMerr]

Closing, cause issue was resolved with RxSwift 5.0