覆盖Scala枚举值 [英] Overriding Scala Enumeration Value

问题描述

据我所知，Scala为Enumeration Value类定义了Value（Int），Value（String）和Value（Int，String）。

As far as I can tell, Scala has definitions for the Enumeration Value class for Value(Int), Value(String), and Value(Int, String).

有人知道创建新的Value子类以支持其他构造函数的示例吗？

Does anyone know of an example for creating a new Value subclass to support a different constructor?

例如，如果我想创建一个Value（Int， String，String）对象，我该怎么办？我想要使​​用Enumeration类的所有其他好处。

For example, If I want to create an Enumeration with Value(Int, String, String) objects, how would I do it? I would like all of the other benefits of using the Enumeration class.

谢谢。

推荐答案

Enumeration值是Val类的实例。可以扩展此类，并且可以添加工厂方法。

The Enumeration values are instance of the Val class. This class can be extended and a factory method can be added.

object My extends Enumeration {
    val A = Value("name", "x")
    val B = Value("other", "y")
    class MyVal(name: String, val x : String) extends Val(nextId, name)
    protected final def Value(name: String, x : String): MyVal = new MyVal(name, x)
}

scala> My.B.id
res0: Int = 1

scala> My.B.x
res1: String = y

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