设计模式之策略模式(strategy)

策略模式原理：策略模式和简单工厂模式有点类似，只是简单工厂模式产生的是对象，策略模式产生的是根据对象产生的算法。

代码如下：

#include <iostream>
#include <string>
#include <vector>
using namespace std;

enum CACHE{FIFO,LRU,RANDOM};
class ReplaceAlgorithm
{
public:
	virtual void replace(){}
};

class FIFOAlgorithm:public ReplaceAlgorithm
{
public:
	virtual void replace(){cout << "FIFO" <<endl;}
};

class LRUAlgorithm:public ReplaceAlgorithm
{
public:
	virtual void replace(){cout << "LRU" <<endl;}
};
class RandomAlgorithm:public ReplaceAlgorithm
{
public:
	virtual void replace(){cout << "Random" <<endl;}
};
class Cache
{

public:
	Cache(enum CACHE cache)
	{
		switch (cache)
		{
		case FIFO:
			m_preplace = new FIFOAlgorithm();
			break;
		case LRU :
			m_preplace = new LRUAlgorithm();
		case RANDOM:
			m_preplace = new RandomAlgorithm();
		default:
			break;
		}
	};
	void replace()
	{
		m_preplace->replace();
	}
private:
	ReplaceAlgorithm *m_preplace;
};

int main()
{
	Cache cache(FIFO);
	cache.replace();
	return 0;
}