问Scala 3宏创建枚举
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Stack Overflow用户

提问于 2021-09-17 18:01:03

回答 1查看 258关注 0票数 1

我想知道是否有可能在Scala 3中编写一个宏，该宏接受一组字符串并将其转换为枚举类型，并以这些字符串为例？

例如，我想编写一个具有从输入元素生成的内部类型的类：

import scala.quoted.*

class Example(myEnumElements:Seq[String]) {
  
  inline def buildEnum(inline elts:Seq[String]): Unit = ${ buildEnumType('elts) }

  def buildEnumType(e: Expr[Seq[String]])(using Quotes, Type[Seq]): Expr[Unit] = '{
    enum MyEnum:
      ???
  }
}
...
// Possibly in another file?

val example = Example(Seq("A","B","C"))

def someConvenienceFunction(e:example.MyEnum) = e match
  case A => "apple"
  case B => "banana"
  case C => "cranberry"
...
// Possibly in another file?

someConvenienceFunction(example.A)  // "apple"
someConvenienceFunction(example.D)  // compile error

scala