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无法在[scala.concurrent.Future]]上获得“pipeTo”方法

akka scala

4

user639466 · 技术社区 · 8 年前

pipeTo 方法[scala.concurrent.Future]]这样:

import akka.pattern.pipe
val future = ...
future pipeTo sender()

不幸的是,我无法做到这一点,我在IDE中遇到了一个错误“无法解析符号管道”。

pipe(future) pipeTo sender()

但我仍然不明白为什么(顺便说一句,我对scala很陌生)。非常感谢您帮助理解这个谜题。

scala 2.12.2 akka 2.5.3

1 回复 | 直到 8 年前

1

16

Tyler 8 年前

你需要有一个 implicit ExecutionContext

import akka.actor.{Actor, ActorSystem, Props}
import akka.pattern.pipe

import scala.concurrent.Future

// Get the implicit ExecutionContext from this import
import scala.concurrent.ExecutionContext.Implicits.global

object Hello extends App {

  // Creating a simple actor
  class MyActor extends Actor {
    override def receive: Receive = {
      case x => println(s"Received message: ${x.toString}")
    }
  }

  // Create actor system
  val system = ActorSystem("example")
  val ref = system.actorOf(Props[MyActor], "actor")

  // Create the future to pipe
  val future: Future[Int] = Future(100)

  // Test
  future pipeTo ref
}

sbt run
[info] <stuff here>
[info] Running example.Hello 
Received message: 100

你必须这么做的原因是 pipeTo 是上的实例函数 PipeableFuture ,和您的常规 Future 必须“增强”到。这是的构造函数 管道未来 ,注意 implicit executionContext: ExecutionContext 参数:

final class PipeableFuture[T](val future: Future[T])(implicit executionContext: ExecutionContext)

功能:

final class PipeableFuture[T](val future: Future[T])(implicit executionContext: ExecutionContext) {
  def pipeTo(recipient: ActorRef)(implicit sender: ActorRef = Actor.noSender): Future[T] = {
    future andThen {
      case Success(r) â recipient ! r
      case Failure(f) â recipient ! Status.Failure(f)
    }
  }
  def pipeToSelection(recipient: ActorSelection)(implicit sender: ActorRef = Actor.noSender): Future[T] = {
    future andThen {
      case Success(r) â recipient ! r
      case Failure(f) â recipient ! Status.Failure(f)
    }
  }
  def to(recipient: ActorRef): PipeableFuture[T] = to(recipient, Actor.noSender)
  def to(recipient: ActorRef, sender: ActorRef): PipeableFuture[T] = {
    pipeTo(recipient)(sender)
    this
  }
  def to(recipient: ActorSelection): PipeableFuture[T] = to(recipient, Actor.noSender)
  def to(recipient: ActorSelection, sender: ActorRef): PipeableFuture[T] = {
    pipeToSelection(recipient)(sender)
    this
  }
}

自从 pipe(future)