event(事件)

事件是一种特殊的委托，只能在类的内部进行+=或 -=操作

为什么我们要用事件，比如

class Cat
    {
        private string CatName;
        private string Catcolor;
        public Cat(string CatName, string Catcolor)
        {
            this.CatName = CatName;
            this.Catcolor = Catcolor;
        }
        public void CatComing ()
        {
            Console.WriteLine(Catcolor+"的"+CatName + "进来了");
            if(Catcome!=null)
            Catcome();
           
        }
        public Action Catcome;
    }
class Mouth
    {
        private string Name;
        private string color;
        public Mouth(string Name, string color,Cat cat)
        {
            this.Name = Name;
            this.color = color;
            cat.Catcome += this.mouthcoming;
        }
        public void mouthcoming() {
           
            Console.WriteLine(color + "的" + Name + "说快跑");
        }
    }
class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat("加菲猫","黄色的");
            Mouth mouth1 = new Mouth("米老鼠", "黑色的",cat);

            cat.CatComing();
            cat.Catcome();//这里可以对Catcome委托进行调用，程序的耦合性提高会有危险
            Console.ReadKey();
        }
    }

为了降低程序的耦合性，将public Action Catcome;声明为事件public event Action Catcome;

public Action Catcome;