Question

有时，我有一个Option[Future[T]] val。我想处理它：

do.something /* Option[A] here */ map { v => // v is of type A here
    doComplexCalculation(v) // it returns Future[T]
} map { v => // I want to get T here, after future becomes resolved. 
             // But here is Future[T] and I shoud do that:
    v map { v => // v is of type T here.

    }
}

从我的观点来看，坏事是增加筑巢水平。我想要更平坦的代码:)我发现的techinc之一是：

do.something /* Option[A] here */ map { v => // v is of type A here
    doComplexCalculation(v) // it returns Future[T]
} getOrElse {
    Future.failed(/* And I should pass Throwable here */)
} map { v => // v is of type T here

}

你能告诉我一个更好的方法吗？在我的解决方案中我不喜欢的事情：

我应该手工制作失败的未来
我应该手动创建Throwable

Answer 1

为什么您的do.something会返回选项开头？如果你想在None的情况下失败，为什么不做。只是扔东西，或者可能返回Try？然后你可以做

doComplexCalculation(do.something.get).map { v: T => 
    ...
}

Answer 2

我认为以下代码是您案例中的最佳选择

def doSomething[A](): Option[A] = ???
def complexCalculation[T](): Future[T] = ???

def someMethod() = {
  val resOption = doSomething()
  resOption match{
    case Some(res) =>{
      complexCalculation() map{ result =>
        println("Future successfully resolved so print res=" + res.toString)
      }
    }
    case None => println("doSomething returned None")
  }
}

斯卡拉。打开选项[Future [T]]的最好方法

2 个答案: