Scala3 枚举语法的最终版本是什么？

Question

我想重写枚举 class 中的方法，如 Add enum construct

中提到的以下示例

enum class Option[+T] extends Serializable {
  def isDefined: Boolean
}
object Option {
  def apply[T](x: T) = if (x != null) Some(x) else None
  case Some[+T](x: T) {
     def isDefined = true
  }
  case None {
     def isDefined = false
  }
}

但是，代码无法在 Scala 3.0 中编译。如何更改代码以使其工作？谢谢。

编辑感谢@Mario Galic 的回答。

我想把一系列的压缩方法归为一个枚举，如下：

enum CompressionMethod:
  def compress(out: OutputStream): OutputStream
  def decompress(in: InputStream): InputStream

  case GZIP extends CompressionMethod: ...
  case BZIP extends CompressionMethod: ...
  case NONE extends CompressionMethod: ...

如果我将所有实现打包为：

enum CompressionMethod:   
  def compress(out: OutputStream): OutputStream = this match
    case NONE  => out
    case BZIP  => a lot codes ..
    case GZIP  => a lot codes ..
    case ...

此外，如果我稍后添加另一个案例，而不只是添加另一个 case instance 本身，我需要修改 compress 方法。类似于：

enum CompressionMethod:
  def compress(out: OutputStream): OutputStream
  
  case GZIP extends CompressionMethod:
    override def compress(out: OutputStream): OutputStream =
      ...

  case BZIP extends CompressionMethod:
    override def compress(out: OutputStream): OutputStream =
      ...

Answer 1

一个技巧是检查最新用法的测试，例如，tests/run/enum-Option1.scala

$ scala3-repl
scala> enum Option1[+T]:
     |   case Some1(x: T)
     |   case None1
     |
     |   def isDefined: Boolean = this match
     |     case None1 => false
     |     case _    => true
     |
// defined class Option1

scala> import Option1.*

scala> Some1(42).isDefined
val res0: Boolean = true

scala> None1.isDefined
val res1: Boolean = false

Scala3 枚举语法的最终版本是什么？

What's the final version of Scala3's enum syntax?

enums

scala

scala-3