I found this in the fact, but i'm not sure to understand the exhaustive
part:
How can I get compile time errors for missing messages in receive?
One solution to help you get a compile time warning for not handling a
message that you should be handling is to define your actors input and
output messages implementing base traits, and then do a match that the will
be checked for exhaustiveness.
Here is an example where the compiler will warn you that the match in
receive isn't exhaustive:
1. object MyActor {
2. // these are the messages we accept
3. sealed abstract trait Message
4. case class FooMessage(foo: String) extends Message
5. case class BarMessage(bar: Int) extends Message
6.
7. // these are the replies we send
8. sealed abstract trait Reply
9. case class BazMessage(foo: String) extends Reply
10. }
11.
12. class MyActor extends Actor {
13. import MyActor._
14. def receive = {
15. case message: Message => message match {
16. case BarMessage(bar) => sender ! BazMessage("Got " + bar)
17. }
18. }
19. }
Could you help and explain, why the compiler will make a warning ?
On Friday, January 3, 2014 11:25:29 AM UTC+1, rkuhn wrote:
>
> Hi Maatary,
>
> if you look at the Akka documentation or browse for blog posts you'll see
> that usually the message types accepted and emitted by an actor are
> declared together with it--in the same package or in its companion object.
> These messages are a perfect match for case classes since they need to be
> immutable and should have appropriate deconstructors for pattern matching:
>
> object MyActor {
> sealed trait Command
> case class DoIt(name: String, id: Int) extends Command
> ... // further commands
>
> sealed trait Reply
> case object Done extends Reply
> }
>
> class MyActor extends Actor {
> def receive = {
> case DoIt(name, id) =>
> // do it
> sender ! Done
> ... // further cases
> }
> }
>
> Regards,
>
> Roland
>
> 2 jan 2014 kl. 03:22 skrev Maatary Okouya <[email protected]<javascript:>
> >:
>
> Hi,
>
> I just start trying myself out with Scala. I grow confident enough to
> start refactoring an ongoing multi-threaded application that i have been
> working on for about a year and half.
>
> However something that somehow bother and i can't somehow figure it out,
> is how to expose the interface/contract/protocole of an Actor? In the OO
> mode, i have my public interface with synchronized method if necessary, and
> i know what i can do with that object. Now that i'm going to use actor, it
> seems that all of that won't be available anymore.
>
> More specifically, I a KbService in my app with a set of method to work
> with that Kb. I want to make it an actor on its own. For that i need to
> make all the method private or protected given that now they will be only
> called by my received method. Hence the to expose the set of available
> behavior.
>
> Is there some best practice for that ?
>
> --
> >>>>>>>>>> Read the docs: http://akka.io/docs/
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>
>
> *Dr. Roland Kuhn*
> *Akka Tech Lead*
> Typesafe <http://typesafe.com/> - Reactive apps on the JVM.
> twitter: @rolandkuhn
> <http://twitter.com/#!/rolandkuhn>
>
>
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