namespace Cat
{
    public delegate void SubEventHandler(object sender,EventArgs e);
    public class Subject
    {
        public event SubEventHandler subEvent;
        public virtual void OnAction(EventArgs e)
        {
            if (subEvent != null)
            {
                subEvent(this, e);
            }
        }
    }

    public abstract class Observer
    {
        private Subject sub;
        public Observer(Subject sub)
        {
            this.sub = sub;
            this.sub.subEvent += new SubEventHandler(ObResult);
        }

        public abstract void ObResult(object sender, EventArgs e);
    }

    class Cat:Subject
    {
        public void Scream()
        {
            Console.WriteLine("貓叫~~");
            OnAction(EventArgs.Empty);
        }
    }

    class Mouse : Observer
    {
        public Mouse(Subject sub)
            : base(sub)
        {

        }

        public override void ObResult(object sender, EventArgs e)
        {
            Console.WriteLine("老鼠嚇跑了~");
        }
    }

    class Master : Observer
    {
        public Master(Subject sub)
            : base(sub)
        {

        }
        public override void ObResult(object sender, EventArgs e)
        {
            Console.WriteLine("主人醒了~");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat();
            Mouse[] mouses = new Mouse[3];
            for (int i = 0; i < mouses.Length; i++)
            {
                mouses[i] = new Mouse(cat);
            }
            Master master = new Master(cat);
            cat.Scream();
            Console.ReadKey();
        }
    }
}