非变量类型参数akka.actor.ActorRef

Question

这是一个涉及akka的代码:

def receive = {
   case idList: List[ActorRef] => idList.foreach(x => x ! Msg)
}

Sbt抱怨说:

non-variable type argument akka.actor.ActorRef in type pattern List[akka.actor.ActorRef] is unchecked since it is eliminated by erasure
[warn]     case idList: List[ActorRef] => idList.foreach(x => x ! Msg)

我怎么摆脱这个？

Answer 1

在运行时List[Whatever]相当于List[Any],所以你的Actor可以弄清楚它收到了一个列表但不是它的列表ActorRef.这是一个JVM的东西,而不是Scala或Akka的错.

你有两个选择:

1)通过替换ActorRef来忽略它_

case idList: List[_] => ...

2)将其包裹到数据结构中(推荐)

case class Ids(idList: List[ActorRef])

第二个选择让你检查ID而不必检查列表的参数类型.

def receive = {
   case Ids(idList) => idList.foreach(x => x ! Msg)
}