Question

This is an elaboration on this question: c# Enum Function Parameters

I created a little sample application to introduce my question:

UPDATE: This is a known difficulty on the C# programming language. I added the used workaround in the code for people that find this in a search engine.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace FlexibleEnums
{
    class Program
    {
        public enum Color
        {
            Blue,
            Red,
            Green
        };

        static void Main(string[] args)
        {
            CheckEnum<Color>();
            Console.ReadKey();
        }

        private static void CheckEnum<T>()
        {
            foreach (T item in Enum.GetValues(typeof(T)))
            {
                Console.WriteLine(item);

                // And here is the question:
                // I would like to uncheck this line, but that does not compile!
                //DoSomethingWithAnEnumValue(item);

                // Solution:
                // Not so nice, but it works.
                // (In the real program I also check for null off cource!)
                DoSomethingWithAnEnumValue(item as Enum);


            }

        }

        private static void DoSomethingWithAnEnumValue(Enum e)
        {
            Console.WriteLine(e);
        }

    }
}

I think that I should be doing something like:

private static void CheckEnum<T>() where T : Enum

But that’s also giving me compile errors.

Thanks for the help!

Answer 1

I think the question can be restated as, ‘how to place generic constraints on an enumeration value’.

Jon Skeet has blogged about it here: http://msmvps.com/blogs/jon_skeet/archive/2009/09/10/generic-constraints-for-enums-and-delegates.aspx

The question has been asked previously on SO