Scala 阿克卡。有没有办法在两个接收器之间共享代码？

假设我有几个接收，并使用been（）unbecome（）在它们之间切换。所有接收都有一些通用的消息处理。像这样：

class Test extends Actor {

  override def receive: Receive = first

  def first: Receive = {
    case "common" => // how to share?
      println("common stuff")
    case "second" =>
      println("move to second")
      context.become(second)
  }

  def second: Receive = {
    case "common" =>  // how to share?
      println("common stuff")
    case "first" =>
      println("move to first")
      context.become(first)
  }

}

现在我看到两种方式：

• “通用”和“通用”上的重复模式匹配 用handleCommon（）之类的函数处理它
• 合并接收类似 这个，但我觉得不对

下面是第二个示例：

class Test extends Actor {

      override def receive: Receive = merge(common, first)

      def common: Receive = {
        case "common" =>
          println("common stuff")
      }

      def first: Receive = {
        case "second" =>
          println("move to second")
          context.become(merge(common, second))
      }

      def second: Receive = {
        case "first" =>
          println("move to first")
          context.become(merge(common, first))
      }

      private def merge(functions: Receive*): Receive = {
        case any =>
          val fOpt = functions find (_.isDefinedAt(any))
          if (fOpt.isDefined) {
            fOpt foreach (f => f(any))
          } else {
            unhandled(any)
          }
      }
    }

---

我相信一定有更好的方法来做到这一点。有吗？

您可以使用

orElse

：

def common: Receive = {
  case "common" =>
    println("common stuff")
}

def first: Receive = ({
  case "second" =>
    println("move to second")
    context.become(second)
}: Receive) orElse common

def second: Receive = ({
  case "first" =>
    println("move to first")
    context.become(first)
}: Receive) orElse common

---

请注意，您必须在表达式末尾显式注释类型，否则scala将推断

Function1

，而不是

Receive

，我想最好使用

val

定义

common

，以便更容易看到它只是一个部分函数，仅用于mix inI，不要认为它太重要，最后，即使它是一个val，它也是一个函数，所以每次调用时都会对它求值，通常我会将这种共享接收设置为私有。这正是我试图编辑我的评论的地方。我想说的是

private val

，而不是

val

。