Scala Publish

[headinthebox]

The current Scala bindings for publish are as follows:

def publish: (() => Subscription, Observable[T]) = {
val javaCO = asJavaObservable.publish()
(() => javaCO.connect(), toScalaObservableT)
}

This has a couple of downsides

• It forces every caller has to invent names for the two pieces, whereas they already have names given by the callee.

  val (foo, bar) = baz.publish()

vs

val bar = baz.publish()
bar.subscribe(..)
bar.connect

• It hides the fact that publish returns a connectable observable, so you cannot call refcount.
• Why split up a nice object into a tuple of unrelated things. Maybe that makes sense if you want to pass the two pieces around separately, but that is typically not the case of connectable observables.

If I don't hear anyone screaming loudly, I am going to change this to mimic the Java signature.

[samuelgruetter]

When I came up with this (() => Subscription, Observable) pattern, the Scala Observable extended AnyVal, so it was final and I could not make a ConnectableObservable extending it. But now this problem is gone, so I think it makes sense to replace (() => Subscription, Observable) by ConnectableObservable (of course, not only in publish, but also in multicast and replay).

There's a similar situation with groupBy: In Java, we have a GroupedObservable<K, T>, and in Scala we have a Observable[(K, Observable[T])]. Here, however, I wouldn't change anything, because an Observable emitting tuples which map keys to Observables makes more sense than claiming that the key is part of the Observable, and also, the tuples allow nice for comprehensions like for ((key, obs) <- o.groupBy(...)).

[benjchristensen]

@headinthebox @samuelgruetter Has this been resolved?

[zsxwing]

Should be resolved in #1160