C#的Delegate和Event

参考：

C# 中的委托和事件

C# 中的委托和事件(续)

我的总结如下： 

1）实例：

namespace Test
{
    public delegate void ProcessEventHandler(string name);
    public class MyTest
    {
        public event ProcessEventHandler myProcessEvent;
    }
}

2) IL代码：

.namespace Test
{
    .class public auto ansi beforefieldinit MyTest
        extends [mscorlib]System.Object
    {
        .method public hidebysig specialname rtspecialname instance void .ctor() cil managed
        {
        }

        .field private class Test.ProcessEventHandler myProcessEvent
        .event Test.ProcessEventHandler myProcessEvent
        {
            .addon instance void Test.MyTest::add_myProcessEvent(class Test.ProcessEventHandler)
            .removeon instance void Test.MyTest::remove_myProcessEvent(class Test.ProcessEventHandler)
        }
    }
 
    .class public auto ansi sealed ProcessEventHandler
        extends [mscorlib]System.MulticastDelegate
    {
        .method public hidebysig specialname rtspecialname instance void .ctor(object 'object', native int 'method') runtime managed
        {
        }
        .method public hidebysig newslot virtual instance class [mscorlib]System.IAsyncResult BeginInvoke(string name, 
           class [mscorlib]System.AsyncCallback callback, object 'object') runtime managed
        {
        }
        .method public hidebysig newslot virtual instance void EndInvoke(class [mscorlib]System.IAsyncResult result) runtime managed
        {
        }
        .method public hidebysig newslot virtual instance void Invoke(string name) runtime managed
        {
        }
    }
} 

3）总结：

委托关键字delegate定义了一种类型；

事件关键字event的定义其实包含两部分，第一定义一个私有的委托的实例，使得外部用户不能直接访问此委托（不管此事件是public或private，此委托总是private），第二通过在IL层增加add和remove方法来对外公开委托的+=和-=从而使外部的用户对此委托赋值或取消赋值；

完！