Associating Additional Information with .NET Enum

Question

My question is best illustrated with an example.

Suppose I have the enum:

public enum ArrowDirection
{
    North,
    South,
    East,
    West
}
         


        

Answer 1

There's a FANTASTIC new way to do this in C# 3.0. The key is this beautiful fact: Enums can have extension methods! So, here's what you can do:

public enum ArrowDirection
{
    North,
    South,
    East,
    West
}

public static class ArrowDirectionExtensions
{
     public static UnitVector UnitVector(this ArrowDirection self)
     {
         // Replace this with a dictionary or whatever you want ... you get the idea
         switch(self)
         {
             case ArrowDirection.North:
                 return new UnitVector(0, 1);
             case ArrowDirection.South:
                 return new UnitVector(0, -1);
             case ArrowDirection.East:
                 return new UnitVector(1, 0);
             case ArrowDirection.West:
                 return new UnitVector(-1, 0);
             default:
                 return null;
         }
     }
}

Now, you can do this:

var unitVector = ArrowDirection.North.UnitVector();

Sweet! I only found this out about a month ago, but it is a very nice consequence of the new C# 3.0 features.

Here's another example on my blog.