こんなかんじで、identityIdとActorSelectionとのコンボで使うらしい。 IdentityのメッセージをActorSelectionに送るときに使うとか。
class Follower extends Actor { val identifyId = 1 context.actorSelection("/user/another") ! Identify(identifyId) def receive = { case ActorIdentity(`identifyId`, Some(ref)) => context.watch(ref) context.become(active(ref)) case ActorIdentity(`identifyId`, None) => context.stop(self) } def active(another: ActorRef): Actor.Receive = { case Terminated(`another`) => context.stop(self) } }