scala - 拦截/装饰一个 PartialFunction

Question

如何拦截 PartialFunction？例如在 Actor 中，如果我只想打印进入以下接收方法的所有内容，然后再将其传递给流程方法:

class MyActor extends Actor {
  def receive : Receive = process
  def process : Receive = {
    case Some(x) => /* do one thing */ ()
    case None => /* do another thing */ ()
    case _ => /* do something else */ ()
  }
}

Answer 1

PartialFunction 是您可以实现的特征。您不会被迫使用 case句法。

不幸的是，它没有提供一种方便的方法来按照您描述的方式进行创作。最接近的是andThen方法，但您传递的参数必须是常规函数，这可能会在实际接收函数中未处理参数时导致匹配错误。所以你一直在写它。

class MessageInterceptor(receiver: Receive) extends Receive {
  def apply(msg: Any) = {
    /* do whatever things here */
    receiver.apply(msg)
  }
  def isDefinedAt(msg: Any) = receiver.isDefinedAt(msg)
}

val process = new MessageInterceptor(receive)