组合多个提取器对象以在一个匹配语句中使用 [英] Combine multiple extractor objects to use in one match statement

问题描述

是否可以在一个 match 语句中运行多个提取器?

Is it possible to run multiple extractors in one match statement?

object CoolStuff {
  def unapply(thing: Thing): Option[SomeInfo] = ...
}
object NeatStuff {
  def unapply(thing: Thing): Option[OtherInfo] = ...
}

// is there some syntax similar to this?
thing match {
  case t @ CoolStuff(someInfo) @ NeatStuff(otherInfo) => process(someInfo, otherInfo)
  case _ => // neither Cool nor Neat
}

这里的目的是有两个提取器，我不必做这样的事情:

The intent here being that there are two extractors, and I don't have to do something like this:

object CoolNeatStuff {
  def unapply(thing: Thing): Option[(SomeInfo, OtherInfo)] = thing match {
    case CoolStuff(someInfo) => thing match {
      case NeatStuff(otherInfo) => Some(someInfo -> otherInfo)
      case _ => None // Cool, but not Neat
    case _ => None// neither Cool nor Neat
  }
}

推荐答案

可以试试

object ~ {
  def unapply[T](that: T): Option[(T,T)] = Some(that -> that)
}

def too(t: Thing) = t match {
  case CoolStuff(a) ~ NeatStuff(b) => ???
}

这篇关于组合多个提取器对象以在一个匹配语句中使用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！