在Akka接收方法中组合Scala中的特征行为

发布时间：2020-12-16 09:37:47 所属栏目：安全来源：网络整理

导读：考虑这两个特点： trait Poked extends Actor { override def receive = { case Poke(port,x) = ReceivePoke(port,x) } def ReceivePoke(port: String,x: Any)}trait Peeked extends Actor { override def receive = { case Peek(port) = ReceivePeek(port)

考虑这两个特点：

trait Poked extends Actor {
  override def receive = {
    case Poke(port,x) => ReceivePoke(port,x)
  }

  def ReceivePoke(port: String,x: Any)
}

trait Peeked extends Actor {
  override def receive = {
    case Peek(port) => ReceivePeek(port)
  }

  def ReceivePeek(port: String)
}

现在考虑我可以创建一个实现两个特征的新的Actor：

val peekedpoked = actorRef(new Actor extends Poked with Peeked)

如何组合接收处理程序？即接收者应该像以下代码一样，虽然“自动生成”(即，所有特征应该组成)：

def receive = (Poked.receive: Receive) orElse (Peeked.receive: Receive) orElse ...

解决方法

您可以使用超级[T]引用特定超级类/特征的成员。

例如：

trait IntActor extends Actor {
    def receive = {
        case i: Int => println("Int!")
    }
}

trait StringActor extends Actor {
    def receive = {
        case s: String => println("String!")
    }
}

class IntOrString extends Actor with IntActor with StringActor {
    override def receive = super[IntActor].receive orElse super[StringActor].receive
}

val a = actorOf[IntOrString].start
a ! 5 //prints Int!
a ! "Hello" //prints String!

编辑：

为了回应雨果的评论，这里有一个解决方案，可以让您组合混音，而无需手动将收音一起接收。本质上它涉及具有可变列表[Receive]的基本特征，并且每个混合特征调用一个方法来将其自己的接收添加到列表中。

trait ComposableActor extends Actor {
  private var receives: List[Receive] = List()
  protected def registerReceive(receive: Receive) {
    receives = receive :: receives
  }

  def receive = receives reduce {_ orElse _}
}

trait IntActor extends ComposableActor {
  registerReceive {
    case i: Int => println("Int!")
  }
}

trait StringActor extends ComposableActor {
  registerReceive {
    case s: String => println("String!")
  }
}

val a = actorOf(new ComposableActor with IntActor with StringActor).start
a ! 5 //prints Int!
a ! "test" //prints String!

唯一要记住的是，收件的顺序不应该是重要的，因为你不能轻易地预测哪一个是链中的第一个，尽管你可以通过使用可变的哈希而不是一个名单。

（编辑：李大同）

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