scala - scala 是否支持多个模式匹配的一个默认子句？

Question

考虑下面的代码:

val first = ...
val second = ...
val third = ...
val fours = ...

first match {
  case "someString" => second match {
    case s:String => third match {
      case MyEnum.A => //some logic
      case MyEnum.B => fours match {
        case Some(old:String) => //some other logic
        case default=> defaulLogic
      }
      case default=> defaulLogic
    }
    case default=> defaulLogic
  }
  case default=> defaulLogic
}

private def defaulLogic()= {
    //log error here
}

有没有办法放case default逻辑到一个地方而不是在每个模式匹配中复制它？

备注

只有顶部match-case声明，其实还有更多的情况。

Answer 1

我会重写代码以使其更易于阅读:

(first, second, third, fours) match {
  case ("something", s: String, MyEnum.A, _) => //some logic
  case ("something", s: String, MyEnum.B, Some(old)) => //some other logic
  case _ => defaulLogic
}

如果你这样写，default case 会用更自然的方式写出来。