Nathan J Pledger

It would be difficult to do. You can't inherit from System.Int32 either. In fact, you cannot inherit from any valuetype in .NET. This is by design. Valuetypes can live "unboxed" on the stack and in that case don't carry a type identifier for the instance. Allowing inheritance would mean you could substitute an instance of a class derived from a valuetype for that valuetype. If you would be able to override a method in the derived class the runtime would have a hard time figuring out which method to call because it can't see if it is dealing with an instance of the parent class or an instance of the derived class. Or in other words valuetypes and polymorphism don't mix very well.

Check out http://blogs.msdn.com/joelpob/archive/2004/07/19/187709.aspx for more details.

YES! I've been wanting that ever since I first learned of enumerations (about 10 years ago ;-).

I think an exception could be made for the enum value type with regard to the inheritance restictions. I dont see anything wrong with inheriting from an existing enum.

Maybe its even enough to implement it as syntactic suger that just copies all the entries of the base type...

I'm tackling a similar problem, and I've come up with a solution that you may or may not like.

(I use vb but you get the idea)

Public Enum StronglyTypedEnum As Int32

CommonEnum1 = 0

CommonEnum2= 1

CommonEnum3= 2

ClassSpecificEnum = 4

End Enum

Public Class BaseClass

    Public Const CommonEnum1 As StronglyTypedEnum = StronglyTypedEnum.CommonEnum1

    Public Const CommonEnum2 As StronglyTypedEnum = StronglyTypedEnum.CommonEnum2

    Public Const CommonEnum3 As StronglyTypedEnum = StronglyTypedEnum.CommonEnum3

End Class

Public Class InheritedClass Inherits BaseClass

   Public Const ClassSpecificEnum As StronglyTypedEnum = StronglyTypedEnum.StronglyTypedEnum  

End Class

Now if you we can do this:

Dim value As StronlyTypedEnum

value = InheritedClass.CommonEnum1

value = InheritedClass.CommonEnum2

value = InheritedClass.CommonEnum3

value = InheritedClass.ClassSpecificEnum

---------------------------------

Of course with this method you lose the ability  to use Enum specific methods, but if you are just after the values, as I am usually this works quite well.  The other pain is that you have to maintain the StronglyTypedEnum Enum separately, but it's a good solution if you care about strongly typed values rather than simple int32's.