One Thing You Can’t Do With Generics in .NET

I thought I’d try to be creative tonight and try this in C# 2.0 [1]:

public class BaseClass 
{
  public int GetTypicalAnswer { return 42; }
}

public class AddMethod<BaseType> : BaseType 
{
  public int GetWackyAnswer() { return 1001001; }
}

public class TestAddMethod
{
  public void Test()
  {
    AddMethod<BaseClass> extendedBaseClass = 
      new AddMethod<BaseClass>();
    int typicalAnswer = extendedBaseClass.GetTypicalAnswer();
    int wackyAnswer = extendedBaseClass.GetWackyAnswer();
  }
}

But such wackiness isn’t allowed:

Error 1: Cannot derive from 'BaseType' because it is a type parameter

Oh well. It’s no big deal, but, man, having this would open up so much wackiness!

[1] I’ve noticed that most of the .NET generic classes use the one-letter capitalization approach for type names, like Dictionary<K, V>. Personally, I like more descriptive variable names (and isn’t that what the generic type name is anyway? At least, sort of?), like Dictionary<Key, Value>. A small issue, but I know some coding standard war will start up on this someday.

Published: 10.20.2004 06:26:57 PM CST

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Jason Bock

One Thing You Can’t Do With Generics in .NET