2策略模式

//策略类
class Strategy
{
public:
     virtual void DoSomething() = 0;
};

class MethodA : public Strategy
{
public:
     void DoSomething()
     {
          cout<<"this is MethodA."<<endl;
     }
};

class MethodB : public Strategy
{
public:
     void DoSomething()
     {
          cout<<"this is MethodB."<<endl;
     }
};

class MethodC : public Strategy
{
public:
     void DoSomething()
     {
          cout<<"this is MethodC."<<endl;
     }
};

//上下文类，根据得到的对象匹配对应的策略类
class Context
{
public:
     Context(Strategy *pStrategy) : m_pStrategy(pStrategy)	//构造函数，给m_pStrategy赋值为对应的策略类指针
     {
     }
     void Execute()		//封装了对应对象的调用
     {
          m_pStrategy->DoSomething();
     }
private:
     Strategy *m_pStrategy;
};


int main()
{
     //创建具体的策略对象
     Strategy *pStrategy = new MethodA;
     //创建调用策略的对象
     Context *pContext = new Context(pStrategy);
     //调用策略的方法
     pContext->Execute();//打印 this is MethodA
   
   rerurn 0;
}