title: How to group Enum values?
body: <p>How can I group Enum values?<br>
  Assume I have an enum like</p>
  
  <pre><code>public enum Colors
    {
      LightBlue,
      LightGreen,
      DarkGreen,
      Black,
      White,
      LightGry,
      Yellow
    }
  </code></pre>
  
  <p>Now I want to define some groups of colors, e.g. the light colors (LightBlue, LightGreen, White, LightGray, Yellow) and dark colors (Black, DarkGreen).<br>
  So I can ask for groups at different places in my code.<br>
  If I remember correctly my Java time I just could add methods to the enums in Java. I think that is not possible in C#. But maybe there are other ways.</p>
  
  <p>Edit1: Of course I can add a Utility class with static member like <code>IsADarkColor(Colors c)</code>. But I would like do it without an additional class because I could forget that related class when I need that feature.</p>