C++设计模式：策略模式

=策略模式：定义了算法家族，分别封装起来，然后定义一个统一的借口，算法之间可以相互替换。使用该模式可以让算法的变化不影响到使用算法的客户。

模式实现：策略模式具体实现时通常与工厂模式相结合，定义一个工厂类，来决定初始化哪个算法。

代码如下：

#include<iostream>using namespace std;enum RA{LRU,FIFO,RANDOM};class ReplaceAlgorithm{public:    virtual void Replace() = 0;};class LRU_ReplaceAlgorithm :public ReplaceAlgorithm{public:    void Replace()    {        cout <<"Least Recently Used replace algorithm"<<endl;    }};class FIFO_ReplaceAlgorithm :public ReplaceAlgorithm{public:    void Replace()    {        cout << "First in First out replace Algorithm" << endl;    }};class random_ReplaceAlgprithm :public ReplaceAlgorithm{public:    void Replace()    {        cout << "Random replace algorithm" << endl;    }};class Cache{private:    ReplaceAlgorithm*m_ra;public:    Cache(RA ra)    {        if (ra == LRU)        {            m_ra = new LRU_ReplaceAlgorithm();        }        else if (ra == FIFO)        {            m_ra = new FIFO_ReplaceAlgorithm();        }        else if (ra == RANDOM)        {            m_ra = new random_ReplaceAlgprithm();        }        else            m_ra = NULL;    }    ~Cache()    {        delete m_ra;        m_ra = NULL;    }    void Replace()    {        m_ra->Replace();    }};