25.委托(2)

1. 上节是用静态方法声明的委托，本节是用动态方法声明委托，使之更灵活。

namespace _25.委托_2_
{
    
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Man xw = new Man("小王");
            Man xl = new Man("小李");
            Man xz = new Man("小赵");
            EatDelegate a = new EatDelegate(xw.eat);
            EatDelegate s = new EatDelegate(xl.eat);
            EatDelegate d = new EatDelegate(xz.eat);
            EatDelegate eatChain = null;
            MessageBox.Show("三人开Part");
            eatChain = a + s + d;
            eatChain ("西瓜");
        }
    }
    delegate void EatDelegate(string food);
    class Man
    {
        private string name;
        public Man(string name)
        {
            this.name = name;
        }
        public void eat(string food)
        {
            MessageBox.Show(name + "吃" + food);
        }
    }
}

2. 接着上面的，传有多个参数的。

 

namespace _25.委托_2_
{
    
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Man xw = new Man("小王");
            Man xl = new Man("小李");
            Man xz = new Man("小赵");
            EatDelegate a = new EatDelegate(xw.eat);
            EatDelegate s = new EatDelegate(xl.eat);
            EatDelegate d = new EatDelegate(xz.eat);
            EatDelegate eatChain = null;
            MessageBox.Show("三人开Part");
            eatTogether("西瓜" , a , s , d);
            MessageBox.Show("xw goes out");
            eatTogether("葡萄" ,s , d);
            MessageBox.Show("xw comes here");
            eatTogether("橘子" ,a , s,d);
            eatTogether(null, null);          
        }
        static void eatTogether (string food, params EatDelegate [] values)
        {
            if (values == null)
            {
                MessageBox.Show("Party is over !");
            }
            else
            {
                EatDelegate eatChain = null;
                foreach (EatDelegate ed in values)
                    eatChain += ed;
                eatChain(food);
                MessageBox.Show("");
            }
        }
    }
    delegate void EatDelegate(string food);
    class Man
    {
        private string name;
        public Man(string name)
        {
            this.name = name;
        }
        public void eat(string food)
        {
            MessageBox.Show(name + "吃" + food);
        }
    }
}