一个关于boxing和unboxing的demo

demo 来自 CLR via C#（第三版）

static void Main(string[] args)
        {
            Point p = new Point(1, 1);
            Console.WriteLine(p);

            p.Change(2, 2);
            Console.WriteLine(p);

            Object o = p;
            Console.WriteLine(o);

            ((Point)o).Change(3, 3);
            Console.WriteLine(o);

            ((IChangeBoxedPoint)p).Change(4, 4);
            Console.WriteLine(p);

            ((IChangeBoxedPoint)o).Change(5, 5);
            Console.WriteLine(o);
         }

    public interface IChangeBoxedPoint
    {
        void Change(Int32 x, Int32 y);
    }

    public struct Point : IChangeBoxedPoint
    {
        private Int32 m_x, m_y;
        public Point(Int32 x, Int32 y)
        {
            m_x = x;
            m_y = y;
        }

        public void Change(Int32 x, Int32 y)
        {
            m_x = x;
            m_y = y;
        }

        public override string ToString()
        {
            return string.Format("({0},{1})", m_x, m_y);
        }
    }