InstanceHelper

gistfile1.cs

public class GenericInstanceHelper<TBase,TI1>
{
    public TBase Instance { get; private set; }

    public TI1 Interface { get; private set; }

    private GenericInstanceHelper() {}

    public static GenericInstanceHelper<TBase, TI1> Create<T>(T instance)
        where T : TBase, TI1
    {
        return new GenericInstanceHelper<TBase, TI1> {Instance = instance, Interface = instance};
    }

    public void Set<T>(T instance)
        where T : TBase, TI1
    {
        Instance = instance;
        Interface = instance;
    }

    public static implicit operator TBase(GenericInstanceHelper<TBase, TI1> instance)
    {
        return instance.Instance;
    }

    public delegate object Callinator(params object[] objs);

    public Callinator this[string name]
    {
        get
        {
            return objs =>
            {
                var method = typeof (TBase).GetMethod(name, objs.Select(o => o.GetType()).ToArray());
                if (method != null)
                    return method.Invoke(Instance, objs);
                method = typeof(TI1).GetMethod(name, objs.Select(o => o.GetType()).ToArray());
                if (method != null)
                    return method.Invoke(Instance, objs);
                throw new ArgumentException("Could not find method " + name);
            };
        }
    }
}

Test.cs

internal interface I
{
    int Foo(int i);
}

internal class B
{
    public int TestFunc(int i)
    {
        return 1;
    }
    public int TestFunc(float i)
    {
        return 2;
    }
}

class Test : B,I
{
    public int Foo(int i)
    {
        return 3;
    }
    public static void Main(string[] args)
    {
        var ih = GenericInstanceHelper<B, I>.Create(new Test());
        Console.WriteLine(ih["TestFunc"](1));
        Console.WriteLine(ih["TestFunc"](1.0f));
        Console.WriteLine(ih["Foo"](1));
    }
}