策略模式

简介

策略模式，定义了一个算法族，并且封装了每一个算法，使它们可以互相替换。策略模式让算法与使用它的客户端独立的变化。

UML类图

示例

策略模式比较常见。人总要学习，正如在开篇中所说，通过读可以，写效果更好，能够通过分享或者教会别人可能会更有效。
策略相关类，strategy.h

#ifndef STRATEGY_H
#define STRATEGY_H
#include <iostream>

using namespace std;
class CLearning
{
public:
    virtual void Learn() = 0;
};

class CReading:public CLearning
{
public:
    void Learn()
    {
        cout<<"Learn by Reading."<<endl;
    }
};

class CWriting:public CLearning
{
    void Learn()
    {
        cout<<"Learn by Writing."<<endl;
    }
};

class CTeaching:public CLearning
{
    void Learn()
    {
        cout<<"Learn by Teaching."<<endl;
    }
};

class CLearningContext
{
public:
    CLearningContext(CLearning* pLearning)
    {
        m_pLearning = pLearning;
    }
    void Learn()
    {
        m_pLearning->Learn();
    }
private:
    CLearning* m_pLearning;
};
#endif

客户端调用，main.cpp

#include "strategy.h"

#define SAFE_DELETE(p) if(p){delete (p); (p) = NULL;}
int main(int argc, char* argv[])
{
    CWriting* pWriting = new CWriting;
    CLearningContext* pContext = new CLearningContext(pWriting);
    pContext->Learn();
    SAFE_DELETE(pWriting);
    SAFE_DELETE(pContext);
    return 0;
}