如何清理"一种类型被推断为'任何''警告？

Question

我有以下代码:

class TestActor() extends RootsActor() {

  // Receive is a type resolving to PartialFunction[Any, Unit]
  def rec2 : Actor.Receive = {   
    case "ping" => println("Ping received!!!")
  }

  def recAll = List(super.receive, rec2)

  // Compose parent class' receive behavior with this class' receive
  override def receive = recAll.reduceLeft { (a,b) => a orElse b }
}

这在运行时正常运行,但会产生以下警告:

[warn] /Users/me/git/proj/roots/src/multi-jvm/scala/stuff/TestActor.scala:18: a type was inferred to be `Any`; this may indicate a programming error.
[warn]  override def receive = recAll.reduceLeft { (a,b) => a orElse b }
[warn]                                                   ^

如何更改此代码以清除警告？

Answer 1

我没有收到有关您的代码的警告。如果使用 orElse 而不使用 reduce 会怎样？

scala> import akka.actor._
import akka.actor._

scala> class RootActor extends Actor { def receive = { case _ => println("bang") }}
defined class RootActor

scala> class TestActor extends RootActor {
     |   def rec2: Actor.Receive = { case "ping" => println("ping") }
     |   override def receive = super.receive orElse rec2
     | }
defined class TestActor

scala>