#include <iostream>using namespace std;class GtkSystem{public:    void Init(int argc, char** argv);    int EventLoop() { cout<<"GtkSystem::EventLoop"<<endl; return 0; }};class QtSystem{public:    void Init(int argc, char** argv);    int EventLoop() { cout<<"QtSystem::EventLoop"<<endl; return 1; }};class LogSystem{public:    static void Logger(const char* text) { cout<<"LogSystem::Logger["<<text<<"]"<<endl; }}; class GuiFacade{public:    GuiFacade();    ~GuiFacade();    int MainLoop();    void Logger(const char* text);private:#ifdef GUI_WITH_GTK    GtkSystem* m_pGuiSystem;#else    QtSystem* m_pGuiSystem;#endif    LogSystem* m_pLogSystem;};GuiFacade::GuiFacade(){#ifdef GUI_WITH_GTK    m_pGuiSystem = new GtkSystem;#else    m_pGuiSystem = new QtSystem;#endif}GuiFacade::~GuiFacade(){    delete m_pGuiSystem;    m_pGuiSystem = NULL;}int GuiFacade::MainLoop(){    return m_pGuiSystem->EventLoop();}void GuiFacade::Logger(const char* text){    LogSystem::Logger(text);}int main(int argc, char *argv[]){    GuiFacade facade;    facade.Logger("GuiSystem Startup");    facade.MainLoop();        return 0;}