How to access objects within an object by mixing in a trait with reflection?

Question

How can I get all of the objects within an object with reflection?

Consider this code:

object MonthDay extends MyEnum {
  //Some important holidays
          


        

Answer 1

You should be able to use the pre-existing Scala Enumeration class: http://www.scala-lang.org/api/current/scala/Enumeration.html

It seems to come very close to your use-case!

Answer 2

Something similar is done in Enumeration.populateNameMap: https://lampsvn.epfl.ch/trac/scala/browser/scala/tags/R_2_8_1_final/src/library/scala/Enumeration.scala

Answer 3

My solution, based on Landei's answer would be:

trait MyEnum{
   def valsOfType[T:Manifest] = {
      val c=implicitly[Manifest[T]].erasure
      for {m <- getClass.getMethods 
           if m.getParameterTypes.isEmpty && c.isAssignableFrom(m.getReturnType)
      } yield (m.invoke(this).asInstanceOf[T])
   }
}

class MonthDay(month:Int,day:Int)

object MonthDay extends MyEnum {
   //maybe you want to call this "holidays" instead
   lazy val values = valsOfType[MonthDay] 

   val NewYear       = new MonthDay( 1,  1)
   val UnityDay      = new MonthDay(11,  9)
   val SaintNicholas = new MonthDay(12,  6)
   val Christmas     = new MonthDay(12, 24)
}

I don't think you should call this MyEnum anymore, because an enumerated type implies a closed set of values.

(Doesn't work if the enumeration values are defined as objects)