使用Singleton对象作为枚举元素的Scala枚举以及迭代它们的可能性？

我已经看过了Scala question about emulating Java’s enum和case classes vs. Enumeration,但似乎太费力,太少的好处.

基本上我想有一个值方法返回DayOfWeek的所有单例对象而不重复几次.

这就是我的代码应该是这样的：

object DayOfWeek extends MyEnum {
  object MONDAY extends DayOfWeek(1)
  object TUESDAY extends DayOfWeek(2)
  object WednESDAY extends DayOfWeek(3)
  object THURSDAY extends DayOfWeek(4)
  object FRIDAY extends DayOfWeek(5)
  object SATURDAY extends DayOfWeek(6)
  object SUNDAY extends DayOfWeek(7)
}

class DayOfWeek(ordinal: Int)

方法值应返回类似如下所示的内容：

val values = Array(MONDAY, TUESDAY, WednESDAY, THURSDAY,
                   FRIDAY, SATURDAY, SUNDAY)

一切都应该在MyEnum特性中发生,所以我只需要扩展它以获得功能.

trait MyEnum {
  val values = this.getClass.getField("MODULE$") etc. etc.
}

有什么建议可以做到这一点吗？
这个想法是值访问类并查找它们正在扩展的类的所有单例对象.

编辑：看起来所有建议都没有考虑到用户也可以创建对象,这当然应该与定义的对象相当.

我会尝试再举一个例子,也许它更清楚：

object MonthDay extends MyEnum {
  //Some important holidays
  object NewYear       extends MonthDay( 1,  1)
  object UnityDay      extends MonthDay(11,  9)
  object SaintNicholas extends MonthDay(12,  6)
  object Christmas     extends MonthDay(12, 24)
}

class MonthDay(month: Int, day: Int)

//Of course the user can create other MonthDays
val myBirthDay = new MonthDay(month, day)

if(!MonthDay.values.contains(myBirthDay)) "Well, I probably have to work"
else "Great, it is a holiday!"

我希望有一个特性(MyEnum),我可以将其混合到持有我的“枚举对象”的对象中,并使用方法返回它们的列表(def值：List [MonthDay])或迭代它们(def next：MonthDay或def上一篇：MonthDay).

PPS：I created a new question for the second part of this question按照Ken Bloom的要求.

解决方法:

这个怎么样？它要求您实际为每个新值调用add方法,但值返回正确的类型.

abstract class MyEnum{

   type Value     //define me to be the value type for this MyEnum

   private var _values:List[Value] = Nil
   def values = _values    
   protected def add(newValue:Value) = {
      _values = newValue::_values
      newValue
   }
}

object DayOfWeek extends MyEnum{
   class Value(val dayNum:Int)
   val SUNDAY    = add(new Value(1))
   val MONDAY    = add(new Value(2))
   val TUESDAY   = add(new Value(3))
   val WednESDAY = add(new Value(4))
   val THURSDAY  = add(new Value(5))
   val FRIDAY    = add(new Value(6))
   val SATURDAY  = add(new Value(7))
}

你现在可以打电话了

println(DayOfWeek.values map (_.dayNum))

如果您需要在不同对象上具有不同方法定义的单例对象,则可以创建如下的匿名类：

add(new Value{
      override def dayNum=8
    })