C++设计模式之职责链模式

          return true;
     }
 
     // The department manager is in?
     bool IsIn()
     {
          return true;
     }
private:
     Manager *m_pHandler;
};
 
// Project supervisor
class PS : public Manager
{
public:
     PS(Manager *handler) : m_pHandler(handler){}
     bool HandleRequest(HolidayRequest *pRequest)
     {
          DM *pDM = dynamic_cast<DM *>(m_pHandler);
          if (pDM != NULL)
          {
               if (pDM->IsIn())
               {
                    return pDM->HandleRequest(pRequest);
               }
          }
          cout<<"PS said:OK."<<endl;
          return true;
     }
private:
     Manager *m_pHandler;
};
int main()
{
     DM *pDM = new DM(NULL);
     PS *pPS = new PS(pDM);
     PM *pPM = new PM(pPS);
     HolidayRequest *pHolidayRequest = new HolidayRequest(10);
     pPM->HandleRequest(pHolidayRequest);
     SAFE_DELETE(pHolidayRequest);
 
     pHolidayRequest = new HolidayRequest(2);
     pPM->HandleRequest(pHolidayRequest);
 
     SAFE_DELETE(pDM);
     SAFE_DELETE(pPS);
     SAFE_DELETE(pPM);
     SAFE_DELETE(pHolidayRequest);
}

 

优缺点

1.降低耦合度；职责链模式使得一个对象不用知道是哪一个对象处理它的请求。对象仅需要知道该请求会被正确的处理。接收者和发送者都没有对方的明确的信息，且链中的对象不需要知道链的结构；