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

If you have a base class that can store data you can enforce compiler safety and use marker interfaces. That's more or less what "Mixins in C# 3.0" from the accepted answer proposes.

public static class ModelBaseMixins
{
    public interface IHasStuff{ }

    public static void AddStuff(this TObjectBase objectBase, Stuff stuff) where TObjectBase: ObjectBase, IHasStuff
    {
        var stuffStore = objectBase.Get>("stuffStore");
        stuffStore.Add(stuff);
    }
}

The ObjectBase:

public abstract class ObjectBase
{
    protected ModelBase()
    {
        _objects = new Dictionary();
    }

    private readonly Dictionary _objects;

    internal void Add(T thing, string name)
    {
        _objects[name] = thing;
    }

    internal T Get(string name)
    {
        T thing = null;
        _objects.TryGetValue(name, out thing);

        return (T) thing;
    }

So if you have a Class you can inherit from 'ObjectBase' and decorate with IHasStuff you can add sutff now