interface IMy

    {

    }

    static class MyFunc

    {

        public static void Func<T>(this T obj) where T : IMy

        {

            Console.WriteLine(obj);

        }

        public static void Func<T>(this T obj, int i, int j) where T : IMy

        {

            Console.WriteLine("{0}  {1}", i, j);

        }

    }

    class MyClass : IMy

    {

        public MyClass()

        {

            this.Func();

            this.Func(, );

        }

    }