装饰者模式示例代码

// 装饰者模式.cpp : Defines the entry point for the console application.
// 参考headfirst设计模式

#include "stdafx.h"

    
/*
            
-------------
             IBeverage   
            -------------
                  |
                  |
         _________|________________________________________
        |                   |                             |

-------------     
-------------                       |
 Esoresso          DarkRoast                     
-----------------------
-------------     -------------                   ICondimentDecorator   
                                                     -----------------------
                                                          |
                                                          |
                                                __________|_______________
                                               |                          |
                                         
-------------          
-------------
                                          Mocha                  Whip        
                                         -------------          -------------
                                
*/

//接口Beverage
//装饰者和被装饰者的共同基类
struct IBeverage
{
public: 
    virtual double Cost() = 0;
    virtual void Desc() = 0;
};

//装饰者类基类
class ICondimentDecorator : public IBeverage
{
};

//具体被装饰者，这是一种饮料
class Esoresso : public IBeverage
{
public:
    double Cost()
    {
        return 1.99;
    }
    void Desc()
    {
        printf(" Esoresso ");
    }
};

//具体被装饰者，这是另一种饮料
class DarkRoast : public IBeverage
{
public:
    double Cost()
    {
        return 2.99;
    }
    void Desc()
    {
        printf(" DarkRoast ");
    }
};

//具体装饰者，这是一种调料
class Mocha : public ICondimentDecorator
{
    IBeverage* m_pBeverage;

public:
    Mocha(IBeverage* pBeverage)
    {
        m_pBeverage = pBeverage;
    }
    double Cost()
    {
        return 0.20 + m_pBeverage->Cost();
    }

    void Desc()
    {
        m_pBeverage->Desc();
        printf(" Mocha ");
    }
};

//具体装饰者，这是另一种调料
class Whip : public ICondimentDecorator
{
    IBeverage* m_pBeverage;

public:
    Whip(IBeverage* pBeverage)
    {
        m_pBeverage = pBeverage;
    }
    double Cost()
    {
        return 0.10 + m_pBeverage->Cost();
    }

    void Desc()
    {
        m_pBeverage->Desc();
        printf(" Whip ");
    }
};

int _tmain(int argc, _TCHAR* argv[])
{
    //客户代码
    IBeverage* pBeverage = new DarkRoast(); //来杯饮料
    pBeverage = new Mocha(pBeverage); //加点Mocha
    pBeverage = new Whip(pBeverage); //加点Whip

    //看看我们的饮料及价格
    pBeverage->Desc();
    printf("/n----------------/nCost: %lf RMB/n/n", pBeverage->Cost());


    pBeverage = new Esoresso(); //再来杯饮料
    pBeverage = new Mocha(pBeverage); //加点Mocha
    pBeverage = new Mocha(pBeverage); //再加点Mocha
    pBeverage = new Whip(pBeverage); //加点Whip

    //再来看看我们的饮料及价格
    pBeverage->Desc();
    printf("/n----------------/nCost: %lf RMB/n/n", pBeverage->Cost());

    return 0;
}