Scala编译错误Vert.x响应未来

Question

override def start(): Unit = {
    vertx.eventBus.sendFuture("anAddress", "message 1").onComplete {
      case Success(result) => {
        println("The handler un-registration has reached all nodes")
      }
      case Failure(cause) => {
        println(s"$cause")
      }
    }
  }

我得到这个错误：

missing parameter type for expanded function
The argument types of an anonymous function must be fully known. (SLS 8.5)
Expected type was: scala.util.Try[io.vertx.scala.core.eventbus.Message[?]] => ?
    vertx.eventBus.sendFuture("anAddress", "message 1").onComplete {
                                                                   ^

我该怎么解决这个？

我使用的是Scala 2.12.8和Vert.x 3.7.1

感谢提前！

Answer 1

以下是解决这个问题的方法：

因此vertx.eventbus.sendfuture返回future[message[T]。future

您在这里所做的是使用一个匿名函数，该函数的参数类型必须完全声明。

我想有两个选择：

1）

vertx.eventBus.sendFuture("anAddress", "message 1").onComplete { x: Try[Message[_]] =>
  x match {
    case Success(result) => {
      println("The handler un-registration has reached all nodes")
    }
    case Failure(cause) => {
      println(s"$cause")
    }
  }
}

2）

// define f
def f(x: Try[Message[_]]) = x match {
  case Success(result) => {
    println("The handler un-registration has reached all nodes")
  }
  case Failure(cause) => {
    println(s"$cause")
  }
}

// and later use it
vertx.eventBus.sendFuture("anAddress", "message 1").onComplete(f)