Introduce a "sending side" (settable) for Deferred

As reported by @vaskir at public Slack:

What if I want to pass it as a channel somewhere, then wait until it’s ready? I do it with a channel like this:

    val reply = Channel<Long>()
    getAndResetCh.send(reply)
    return reply.receive()
}

so I send a message to an actor “do the job, then send the result to this channel when ready”, then I wait on receive asynchronously.

So, the use-case is basically to send some object to remote actor to receive a single answer from it. How to we name such and object and what would its “sending” (setting) function be named?

[elizarov]

I’m inclining to introduce a class named Completable<T> that implements Deferred<T> and has the following two functions:

fun complete(value: T): Boolean
fun completeWithException(exception: Throwable): Boolean

Both functions return false when invoked on an already completed instance.

[elizarov]

Released in version 0.17