Chain of Responsibility

#include "stdafx.h"#include <iostream>#include <Windows.h>#include <boost/shared_ptr.hpp>using namespace std;using namespace boost;/***@briefChain Of Responsibility 职责链模式，属于GOF 23种设置模式中的行为模式的一种*意图：使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止*/typedef int Topic;const Topic NO_HELP_TOPIC = -1;const Topic TOPIC_APPLICATION = 1;const Topic TOPIC_DIALOG = 2;const Topic TOPIC_BUTTON = 3;/** @brief 帮助请求 */class HelpHandle{public:HelpHandle(HelpHandle* pHelpHandle,Topic topic = NO_HELP_TOPIC) : m_pHelpHandle(pHelpHandle),m_Topic(topic) {}virtualvoidHelp(){if(m_pHelpHandle != NULL)m_pHelpHandle->Help();}virtualBOOLHasHelp(){return m_Topic != NO_HELP_TOPIC;}virtualvoidSetHandle(HelpHandle* pHelpHandle,Topic topic){m_pHelpHandle = pHelpHandle;m_Topic = topic;}private:HelpHandle*m_pHelpHandle;Topicm_Topic;};/** @brief 应用程序帮助 */class HelpHandle_Application : public HelpHandle{public:HelpHandle_Application(Topic topic = NO_HELP_TOPIC) : HelpHandle(NULL,topic) {}virtualvoidHelp(){if(HasHelp())cout << "Application HelpHandle" << endl;elseHelpHandle::Help();}};/** @brief 对话框帮助 */class HelpHandle_Dialog : public HelpHandle{public:HelpHandle_Dialog(HelpHandle* pHelpHandle,Topic topic = NO_HELP_TOPIC) : HelpHandle(pHelpHandle,topic) {}virtualvoidHelp(){if(HasHelp())cout << "Dialog HelpHandle" << endl;elseHelpHandle::Help();}};/** @brief 按扭帮助 */class HelpHandle_Button : public HelpHandle{public:HelpHandle_Button(HelpHandle* pHelpHandle,Topic topic = NO_HELP_TOPIC) : HelpHandle(pHelpHandle,topic) {}virtualvoidHelp(){if(HasHelp())cout << "Button HelpHandle" << endl;elseHelpHandle::Help();}};int _tmain(int argc, _TCHAR* argv[]){shared_ptr<HelpHandle_Application>pApplicationHelp(new HelpHandle_Application(TOPIC_APPLICATION));shared_ptr<HelpHandle_Dialog> pDialogHelp(new HelpHandle_Dialog(pApplicationHelp.get(),TOPIC_DIALOG));shared_ptr<HelpHandle_Button> pButtonHelp1(new HelpHandle_Button(pDialogHelp.get(),TOPIC_DIALOG));shared_ptr<HelpHandle_Button> pButtonHelp2(new HelpHandle_Button(pDialogHelp.get(),NO_HELP_TOPIC));pButtonHelp1->Help();pButtonHelp2->Help();/***输出结果为*Button HelpHandle*Dialog HelpHandle*/system("pause");return 0;}