you should not be implementing a disposable with a lambda

@jw, you mean, I should create an Disposable, like this:

emitter.setDisposable(Disposables.fromAction {
             orderReference.child(id).removeEventListener(listener)
            })

yep. but if you're doing that you should probably just use the

setCancellable

which will handle creating that wrapper for you and allow you to use the superior lambda

@jw, thanks, really. than I just don’t get what’s the difference between setCancellable() and setDisposable() if we only want to get a callback when this stream is unsubscribed.

cancellable is the callback, disposable is a disposable which is a more involved type that has a lifecycle and idempotency associated