Add optional PipeTo completion handlers

[emilingerslev]

Added an optional success and failure handler to PipeTo, to simplify use of Tasks. PipeTo falls back to original behavior either handler isn't supplied.

Some examples:

Context.ActorSelection("akka.tcp://remote@remote:1234/user/PingActor")
    .ResolveOne(TimeSpan.FromSeconds(1))
    .PipeTo(Self,
        success: x => new PleasePing(x),
        failure: e => new TryAgainLater(e.ToString()));

actorRef.Ask<Pong>(new Ping())
    .PipeTo(Self,
        failure: e => new TryAgainLater(e.ToString()));

[Horusiath]

👍 Great idea! Mapping result or failure before sending in PipeTo is quite common pattern. It would be nice to have this support build into Akka itself.

[rogeralsing]

This is great!!

[emilingerslev]

Glad you like it! It works perfect in what I've working on.

I'm not sure though how much is allowed in the Task.ContinueWith handling? Can you say something like its best practice to only do conversions to new message types or would something like this be alright?:

Context.ActorSelection("akka.tcp://remote@remote:1234/user/PingActor")
    .ResolveOne(TimeSpan.FromSeconds(1))
    .PipeTo(Self,
        success: x => x.Ask<Pong>(new Ping()),
        failure: e => new TryAgainLater(e.ToString()));

I think the syntax becomes more dirty and harder to read, but it would be great with some guidelines.
I would gladly help updating the docs too.

[emilingerslev]

BTW, do you know why the build has gone rogue like?

[Aaronontheweb]

Reverted this- please add unit tests and resubmit

[emilingerslev]

Alright, I'll look into creating a few tests for this

[Aaronontheweb]

Thanks!

[emilingerslev]

Resubmitted it as #1383