装饰图案&扩展方法在c＃

问题描述

首先要描述我的问题，我想定义Decorator和扩展方法
装饰器

扩展方法

我在c＃中有以下代码片段

  public interface IMyInterface 
 {
 void Print（）; 
} 
 
 public static class Extension 
 {
 public static void PrintInt（this IMyInterface myInterface，int i）
 {
 Console.WriteLine 
（Extension.PrintInt（this IMyInterface myInterface，int i））; 
} 
 
 public static void PrintString（this IMyInterface myInterface，string s）
 {
 Console.WriteLine 
（Extension.PrintString（this IMyInterface myInterface ，string s））; 
} 
} 
 
 public class Imp：IMyInterface 
 {
 #region IMyInterface成员
 
 public void Print（）
 {
 Console.WriteLine（Imp）; 
} 
 
 #endregion 
} 
 
类程序
 {
 static void Main（string [] args）
 {
 Imp obj = new Imp（）; 
 obj.Print（）; 
 obj.PrintInt（10）; 
} 
} 
  

在上面的代码中，我将扩展接口而不修改现有的代码，这两个方法可用于派生类。所以我的问题是：扩展方法是否替代了装饰器模式？

解决方案

扩展方法真的只是语法糖用于调用静态方法。

尽管使用装饰器，您实际上可以更改装饰类的行为，扩展方法只能在类上更改属性或调用方法，就像普通静态方法。

装饰模式实际上被定义为使用包装器来改变行为，扩展方法显然不会做。

Before going to describe my problem first,I would like to define definitions of Decorator and Extension methodDecorator

Extension method

I have following code snippet in c#

public interface IMyInterface
{
    void Print();
}

public static class Extension
{
    public static void PrintInt(this IMyInterface myInterface, int i)
    {
        Console.WriteLine
            ("Extension.PrintInt(this IMyInterface myInterface, int i)");
    }

    public static void PrintString(this IMyInterface myInterface, string s)
    {
        Console.WriteLine
            ("Extension.PrintString(this IMyInterface myInterface, string s)");
    }
}

public class Imp : IMyInterface
{
    #region IMyInterface Members

    public void Print()
    {
        Console.WriteLine("Imp");
    }

    #endregion
}

class Program
{
    static void Main(string[] args)
    {
        Imp obj = new Imp();
        obj.Print();
        obj.PrintInt(10);
    }
}

In the above code I am extending interface without modifying the existing code,and these two methods are available to derived class. So my question is this: Is the extension method a replacement of the decorator pattern?

解决方案

A extension method is really just syntactic sugar for calling a static method.

While with a decorator you could actually change the behaviour of your decorated class, a extension method could only alter properties or call methods on your class, just like an "ordinary" static method.

Decorator pattern is actually definied as using a wrapper to alter behaviour, which a extension method clearly doesn't do.

这篇关于装饰图案&扩展方法在c＃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！