Question

var exit: String = expensiveOperation
if (exit.contains(...)) exit = somethingElse

关键是我只想打电话

expensiveOperation

因为它消耗了许多时钟周期

Answer 1

如果您不想公开其他val，请进行内联：

val exit = {
  val result = expensiveOperation
  if (result.contains(...)) somethingElse
  else result
}

或者，如果你愿意

val exit = expensiveOperation match {
  case res if res.contains(...) => somethingElse
  case res if res.contains(...) => somethingBetter
  // ...
  case res => res
}

Answer 2

一个愚蠢的解决方案：只是引入另一个val。

   val expected = expensiveOperation 
   val exit = if(expected.contains(...)) expected else something else

Answer 3

一种可能的解决方案：提取方法。

def exitValue(...): String = {
    val exit: String = expensiveOperation
    if (exit.contains(...)) somethingElse else exit
}

val exit = exitValue(...)

如何将以下var Scala代码转换为val？

3 个答案: