scala中的异步:宏尚未扩展

Question

我不确定为什么这个简单的代码会导致错误:

object Main {

  def main(args: Array[String]) {
    val userInterrupted: Future[String] = async {
      var inp =   await { Future.userInput("")}
      "You entered... " + inp
    }
  }
}

错误消息:

[error] /Users/reactive programming coursera/nodescala/src/main/scala/nodescala/Main.scala:18: macro has not been expanded
[error]     val userInterrupted: Future[String] = async {
[error]                                           ^
[error] one error found
[error] (assignment/compile:compile) Compilation failed

Answer 1

这似乎是一个已知的问题(已经修复但可能在Scala 2.11之前不可用).因为它与隐式有关,你可以尝试通过隐式显式来解决它:

var inp = await { FutureCompanionOps(Future).userInput("") }

(由于这个问题与Coursera赋值有关,我知道你已经定义了implicit class FutureCompanionOps[T]一个带有类型参数的东西,这似乎是问题所在.)