title: Scala, library akka.actor
body: <p>I'm new to Scala actors and I do not get why my code isn't compiling.
  Apparently '?' is not a member, I already imported the akka.actors.patern._ but it's still not working.
  Could anyone clarify this dark thing a bit please?
  Thanks !</p>
  
  <pre><code>import akka.actor.{Actor, ActorRef}
  import akka.pattern._
  
  class Registry extends Actor {
    import Registry._
    var registry:Map[String, Any] = Map()
    def receive = {
      case Lookup(name) =&gt; sender ! registry.get(name)
    }
  }
  
  object Registry {
    import akka.actor.{ActorSystem, Props}
    case class Lookup(name: String)  
    // create dedicated actor infrastructure
    val system = ActorSystem("myActorInfrastructure")
    // create actor with a name and register it with the infrastructure
    def apply(name: String) = system.actorOf(Props(new Registry()), name) 
  }
  
  class Tweeter(val name: String, val regist:Registry, var followers:List[ActorRef]=List()) extends Actor{
      import Tweeter._
      def receive = {
        case Follow(user) =&gt; {
          //Here is the error
          (regist!? Lookup(name)) match{
          case Some(a:ActorRef) =&gt; a ! AddFollower(sender)
          }
        }
        case AddFollower(follower) =&gt; followers = follower::followers 
    }
  }
  
  object Tweeter {
      import akka.actor.{ActorSystem, Props}
    case class Follow(user: String)
    case class AddFollower(follower: ActorRef)
    def apply(name: String, annuaire:Registry) = Registry.system.actorOf(Props(new Tweeter(name,annuaire))) 
  }
  </code></pre>