策略模式

策略模式（Strategy）:定义了算法家族，分别封装起来，让它们之间可以互相替换，此模式让算法的变化，不会影响到使用算法的客户。[DP]

以下为策略模式的实现代码。

#include<iostream>
using namespace std;

class Strategy{
public:
    Strategy(void){}
    virtual ~Strategy(void){}

    virtual void AlgorithmInterface()=0;
};

class ConcreteStrategyA:public Strategy{
public:
    void AlgorithmInterface(){
        cout<<"ConcreteStrategyA:AlgorithmInterface()"<<endl;
    }
};

class ConcreteStrategyB:public Strategy{
public:
    void AlgorithmInterface(){
        cout<<"ConcreteStrategyB:AlgorithmInterface()"<<endl;
    }
};

class Context{
private:
    Strategy* strategy;
public:
    Context(Strategy* s):strategy(s){}
    void setStrategy(Strategy* s){
        strategy=s;
    }
    void otherOperators(){
        cout<<"other operators"<<endl;
    }

    void execute(){
        if(strategy)
            strategy->AlgorithmInterface();
        otherOperators();
    }
};

int main()
{
    ConcreteStrategyA strategyA;
    ConcreteStrategyB strategyB;
    Context context(&strategyA);
    context.execute();
    context.setStrategy(&strategyB);
    context.execute();

         return 0;
}