using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(string.Join(", ", Utils.AsOptions<MyEnum>()));

    }

    public enum MyEnum 

    {

        A,

        B,

        C,

        D

    }

}

​

public static class Utils

{

    /* Enum is a struct and implements IConvertible, unfortunately C# prevents Enum type constraints */

    public static IEnumerable<T> AsOptions<T>() where T : struct, IConvertible

    {

        if (!typeof(T).IsEnum) throw new ArgumentException("T must be an enumerated type");     

        return Enum.GetValues(typeof(T)).Cast<T>();

    }

}