Extension method on enumeration, not instance of enumeration

Question

I have an enumeration for my Things like so:

public enum Things
{
   OneThing,
   AnotherThing
}

I would like to write an extension method

Answer 1

The closest you can come, I think, is to dummy things up a bit to work like an enum without being one. Here's what I've come up with--it seems like a lot of work just to plop a static method on an enumeration, although I do understand the programming appeal of it:

    public class PseudoEnum
{
    public const int FirstValue = 1;
    private static PseudoEnum FirstValueObject = new PseudoEnum(1);

    public const int SecondValue = 2;
    private static PseudoEnum SecondValueObject = new PseudoEnum(2);

    private int intValue;

    // This prevents instantation; note that we cannot mark the class static
    private PseudoEnum() {}

    private PseudoEnum(int _intValue)
    {
        intValue = _intValue;
    }

    public static implicit operator int(PseudoEnum i)
    {
        return i.intValue;
    }

    public static implicit operator PseudoEnum(int i)
    {
        switch (i)
        {
            case FirstValue :
                return FirstValueObject;
            case SecondValue :
                return SecondValueObject;
            default:
                throw new InvalidCastException();
        }
    }

    public static void DoSomething(PseudoEnum pe)
    {
        switch (pe)
        {
            case PseudoEnum.FirstValue:
                break;
            case PseudoEnum.SecondValue:
                break;
        }
    }

}