Switch statement without default when dealing with enumerations

Question

This has been a pet peeve of mine since I started using .NET but I was curious in case I was missing something. My code snippet won\'t compile (please forgive the forced nat

Answer 1

Instead of complaining about how the switch statement works, avoid it entirely by using an extension method on the enum as explained here and here.

The nice thing about this approach is, you don't get into a situation and forgetting to update your GetDecision switch statement when adding a new enum value because it's all together in the same place - in the enum declaration.

The efficiency of this approach is not known to me and, really, not even a consideration at this point. That's right, I just don't care because it's so much easier for me that I figure, "Phhhtt screw the computer that's what it's there for - to work hard." (I may regret that attitude when Skynet takes over.)

If I ever need to get from one of those attribute values back to the enum value, I can simply build a reverse dictionary of and fill it with a single line of code.

(I usually do a 'not set' as the first enum element because, as the OP notes, a C# enum is really an int so an uninitialized variable is going to be zero or the first enum value)

public enum Decision
{
  [DisplayText("Not Set")]
  NotSet,
  [DisplayText("Yes, that's my decision")]
  Yes,
  [DisplayText("No, that's my decision")]
  No
}

public static class XtensionMethods
{
  public static string ToDisplayText(this Enum Value)
  {
    try
    {
      Type type = Value.GetType();
      MemberInfo[] memInfo =
        type.GetMember(Value.ToString());

      if (memInfo != null && memInfo.Length > 0)
      {
        object[] attrs = memInfo[0]
          .GetCustomAttributes(typeof(DisplayText), false);
        if (attrs != null && attrs.Length > 0)
          return ((DisplayText)attrs[0]).DisplayedText;
      }
    }
    catch (Exception ex)
    {
      throw new Exception(
        "Error in XtensionMethods.ToDisplayText(Enum):\r\n" + ex.Message);
    }
    return Value.ToString();
  }

  [System.AttributeUsage(System.AttributeTargets.Field)]
  public class DisplayText : System.Attribute
  {
    public string DisplayedText;

    public DisplayText(string displayText)
    {
      DisplayedText = displayText;
    }
  }
}

Use inline like:

myEnum.ToDisplayText();

Or wrapped in a function, if you feel like it:

public string GetDecision(Decision decision)
{
  return decision.ToDisplayText();
}