Scala case class 在接收方法中不匹配（在 akka actors 中）

Question

我有这样的东西：

class ProbeActor extends Actor {
  case class Probe(messageKey: String)
  def receiveProbe: Receive = {
    case Probe(probeKey) => println("Good probe: "+probeKey)
    case x => println("Bad probe: "+ x)
  }
  final override def receive = receiveProbe orElse receiveOther
  def receiveOther: Receive = {
    case _ => println("Other")
  }
}

我这样称呼它：

class Prober extends ProbeActor {
  val definite = ActorSystem("ProbeTest").actorOf(Props[ProbeActor], name = "probed")
  implicit val timeout = Timeout(5 second)
  val future = definite ? Probe("key")
}

我希望应该打印文本 "Good probe: key"，但我得到 "Bad probe: Probe(key)"。

注意：如果我把Probe外壳class放在外面，就可以正常工作了。

Answer 1

经过更多搜索，我在 scala-lang.org 上找到了答案：

I think the underlying misconception is about the identity of nested class types.

In

class A { class B }

each new instance of class A x creates a new type x.B. And if you do the plain pattern match inside of A you are referring to the specific instance of the type B this.B.

Answer 2

一种在 Probe 上进行模式匹配而不将其移出 class 的方法是

case probe: ProbeActor#Probe => println("Good probe: "+probe.messageKey)

当然，把它移到外面（比如移到伴生对象）是更好的解决办法；正如 Archeg 提到的，特别是在 Akka 中，以避免直接引用演员。

Scala case class 在接收方法中不匹配（在 akka actors 中）

Scala case class is not matched in receive method (in akka actors)

scala

pattern-matching

case-class

akka