Question

我有这样的代码：

   def fn(operatorType: (Int, Int) => Boolean) {
      operatorType match {
         case ((Int, Int) => _ == _)  => //dosomething
         case ((Int, Int) => _ > _)  => //dosomething
      }
   }
   fn((a: Int, b: Int) => a > b)
   fn((a: Int, b: Int) => a == b)

是否可以知道已将哪种布尔表达式传递给该方法？还是有更好的方法来实现相同的逻辑？我必须严格将方法保留为lambda表达式的一个参数。

Answer 1

这是@LuisMiguelMejiaSuarez建议的示例：

sealed trait Op extends ((Int, Int) => Boolean)
case object Equal extends Op {
  def apply(a: Int, b: Int): Boolean = a == b
}
case object GreaterThan extends Op {
  def apply(a: Int, b: Int): Boolean = a >= b
}
case object LessThan extends Op {
  def apply(a: Int, b: Int): Boolean = a <= b
}
case object NotEqual extends Op {
  def apply(a: Int, b: Int): Boolean = a != b
}

def fn(operatorType: Op) = 
  operatorType match {
    case Equal  => //do something with Equal.apply
    case GreaterThan => //do something with GreaterThan.apply
    case LessThan => //do something with LessThan.apply
    case NotEqual => //do something with NotEqual.apply
  }

fn(Equal)

有没有办法在Scala中匹配（切换大小写）lambda表达式？

1 个答案: