user2110292 user2110292 - 7 days ago 4x
C# Question

How to add extension methods to Enums

I have this Enum code:

enum Duration { Day, Week, Month };

Can I add a extension methods for this Enum?


According to this site:

Extension methods provide a way to write methods for existing classes in a way other people on your team might actually discover and use. Given that enums are classes like any other it shouldn’t be too surprising that you can extend them, like:

enum Duration { Day, Week, Month };

static class DurationExtensions {
  public static DateTime From(this Duration duration, DateTime dateTime) {
    switch duration {
      case Day:   return dateTime.AddDays(1);
      case Week:  return dateTime.AddDays(7);
      case Month: return dateTime.AddMonths(1);
      default:    throw new ArgumentOutOfRangeException("duration")

I think enums are not the best choice in general but at least this lets you centralize some of the switch/if handling and abstract them away a bit until you can do something better. Remember to check the values are in range too.

You can read more here at Microsft MSDN.