Is it possible to implement mixins in C#?

Question

I've heard that it's possible with extension methods, but I can't quite figure it out myself. I'd like to see a specific example if possible.

Thanks!

Answer 1

Check this articles:

• Implementing Mixins with C# Extension Methods
• Mixins in C# 3.0

Answer 2

It really depends on what you mean by "mixin" - everyone seems to have a slightly different idea. The kind of mixin I'd like to see (but which isn't available in C#) is making implementation-through-composition simple:

public class Mixin : ISomeInterface
{
    private SomeImplementation impl implements ISomeInterface;

    public void OneMethod()
    {
        // Specialise just this method
    }
}

The compiler would implement ISomeInterface just by proxying every member to "impl" unless there was another implementation in the class directly.

None of this is possible at the moment though :)

Answer 3

LinFu and Castle's DynamicProxy implement mixins. COP (Composite Oriented Programming) could be considered as making a whole paradigm out of mixins. This post from Anders Noras has useful informations and links.

EDIT: This is all possible with C# 2.0, without extension methods