委托和事件 [英] delegates and events

问题描述

我创建了一个非常简单的虚拟程序来理解委托和事件。在我下面的程序，我简单的调用方法。当我打电话的方法，五种方法将被自动调用委托和事件的帮助。

请看看我的程序，做让我知道我错了。或右侧，因为这是一个使用委托和事件我第一次

 使用系统; 
 
命名ConsoleApplication1 
 {
公众委托无效MyFirstDelegate（）; 
 
类测试
 {
公共事件MyFirstDelegate myFirstDelegate; 
 
公共无效调用（）
 {
 Console.WriteLine（欢迎在世界上代表..）; 
如果（myFirstDelegate！= NULL）
 {
 myFirstDelegate（）; 
} 
} 
} 
 
类AttachedFunction 
 {
公共无效firstAttachMethod（）
 {
控制台。的WriteLine（ONE ...）; 
} 
公共无效SecondAttachMethod（）
 {
 Console.WriteLine（两个...）; 
} 
公共无效thirdAttachMethod（）
 {
 Console.WriteLine（三......）; 
} 
公共无效fourthAttachMethod（）
 {
 Console.WriteLine（四......）; 
} 
公共无效fifthAttachMethod（）
 {
 Console.WriteLine（五......）; 
} 
} 
 
类MyMain 
 {
公共静态无效的主要（）
 {
测试测试=新测试（ ）; 
 AttachedFunction attachedFunction =新AttachedFunction（）; 
 test.myFirstDelegate + =新MyFirstDelegate（attachedFunction.firstAttachMethod）; 
 test.myFirstDelegate + =新MyFirstDelegate（attachedFunction.SecondAttachMethod）; 
 test.myFirstDelegate + =新MyFirstDelegate（attachedFunction.thirdAttachMethod）; 
 test.myFirstDelegate + =新MyFirstDelegate（attachedFunction.fourthAttachMethod）; 
 test.myFirstDelegate + =新MyFirstDelegate（attachedFunction.fifthAttachMethod）; 
 
 test.Call（）; 
到Console.ReadLine（）; 
} 
} 
} 
  

解决方案

事件是使用委托实施。按照惯例事件表示采取以下形式：

 无效事件处理（对象发件人，EventArgs参数）; 
  

的事件处理实际上是在.net中定义的代表。 EventArgs的是.NET中的一类，它作为一个占位符来传递更多的信息。如果你有更多的信息，你会创建一个从EventArgs的派生和包含的附加数据属性的类;因此，你可以创建自己的委托，像这样：

 无效一个MyEventHandler（对象发件人，MyEventArgs参数）; 
  

微软对事件教程的这里还介绍定义和认识活动的这里

I have created a very simple dummy program to understand Delegates and events. In my below program I am simple calling a method. When I call a method, five methods are automatically called with the help of delegates and events.

Kindly take a look at my program and do let me know where I am wrong or right as this is my first time using delegates and events.

using System;

namespace ConsoleApplication1
{
    public delegate void MyFirstDelegate();

    class Test
    {
        public event MyFirstDelegate myFirstDelegate;

        public void Call()
        {
            Console.WriteLine("Welcome in Delegate world..");
            if (myFirstDelegate != null)
            {
                myFirstDelegate();
            }
        }        
    }

    class AttachedFunction
    {
        public void firstAttachMethod()
        {
            Console.WriteLine("ONE...");
        }
        public void SecondAttachMethod()
        {
            Console.WriteLine("TWO...");
        }
        public void thirdAttachMethod()
        {
            Console.WriteLine("THREE...");
        }
        public void fourthAttachMethod()
        {
            Console.WriteLine("FOUR...");
        }
        public void fifthAttachMethod()
        {
            Console.WriteLine("FIVE...");
        }
    }

    class MyMain
    {
        public static void Main()
        {
            Test test = new Test();
            AttachedFunction attachedFunction = new AttachedFunction();
            test.myFirstDelegate += new MyFirstDelegate(attachedFunction.firstAttachMethod);
            test.myFirstDelegate += new MyFirstDelegate(attachedFunction.SecondAttachMethod);
            test.myFirstDelegate += new MyFirstDelegate(attachedFunction.thirdAttachMethod);
            test.myFirstDelegate += new MyFirstDelegate(attachedFunction.fourthAttachMethod);
            test.myFirstDelegate += new MyFirstDelegate(attachedFunction.fifthAttachMethod);

            test.Call();
            Console.ReadLine();
        }
    }
}

解决方案

Events are implemented using Delegates. That said by convention events take the form of:

 void EventHandler(Object sender, EventArgs args);

EventHandler is actually a delegate defined in .Net. EventArgs is a class in .Net that acts as a placeholder to pass additional information. If you have additional information you would create a class that derived from EventArgs and contained properties for the additional data; therefore you would create your own delegate like so:

void MyEventHandler(Object sender, MyEventArgs args);

Microsoft has a tutorial on events here and also describes defining and raising events here

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