设计模式 - Strategy

意图：定义一系列的算法,把它们一个个封装起来, 并且使它们可相互替换。本模式使得算法可独立于使用它的客户而变化。

class Strategy
{
public:
    Strategy()
    {}
    virtual ~Strategy()
    {}
    virtual void AlgorithmInterface() = 0;
};

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

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

class Context
{
public:
    Context(Strategy* strategy)
    {
        this->strategy = strategy;
    }
    ~Context()
    {}
    void DoAction()
    {
        strategy->AlgorithmInterface();
    }

private:
    Strategy* strategy;
};