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using System;
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namespace ConsoleApplication1
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{
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public delegate void PrintCallback(int number);
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public class Printer
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{
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private PrintCallback _print;
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public PrintCallback PrintCallback
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{
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get {return _print;}
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set {_print = value;}
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}
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}
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class Driver
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{
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private void PrintInteger(int number)
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{
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Console.WriteLine("The number is {0}",number);
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}
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static void Main(string[] args)
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{
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Driver driver = new Driver();
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Printer printer = new Printer();
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printer.PrintCallback = new PrintCallback(driver.PrintInteger);
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printer.PrintCallback(10);
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printer.PrintCallback(1000);
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}
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}
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}
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![](/Images/OutliningIndicators/None.gif)
这个例子所做的事情就是:定义了一个名为PrintCallback的委托;Printer类具有PrintCallback类型的委托属性PrintCallback。Driver类定义了一个PrintInteger方法,再Main方法中,Driver类将Printer实例的PrintCallback委托绑定到PrintInteger方法。
现在无论什么时候调用PrintCallback委托,它所绑定的方法PrintInteger就会被执行。
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委托是用来处理其他语言(如 C++、Pascal 和 Modula)需用函数指针来处理的情况的。不过与 C++ 函数指针不同,委托是完全面对对象的;另外,C++ 指针仅指向成员函数,而委托同时封装了对象实例和方法。
委托实例封装一个调用列表,该列表列出一个或多个方法,其中每个方法均作为一个可调用实体来引用。