} } }

    C++ FastDelegate 扩大,实现与.net类似的事务处理惩罚功能

    添加时间:2013-8-5 点击量:

    熟悉.NET的人都知道,  .NET应用委托可以快速实现调查者模式,免除写很多错杂反复的代码。遗憾的是,C++并没有供给如许的模型,为了达到类似的目标,须要持续一个类并重写virtual办法,这种做法须要写很多代码,效力斗劲低下。然而,在强大的C++面前,没有什么是不成能的,已经有很多人针对这个题目进行过研究,并且实现了各类委托模型,此中最有名的就是FastDelegate。为了让应用FastDelegate更象.NET,我新添加几个模板,首要如下:

     

    起首添加一个两个类用于模仿事务产生源及事务参数类:

       1: // 定义事务发送源(类似于.net的sender)



       2: class IEventSource



       3: {



       4: public:



       5:     virtual ~IEventSource (){}



       6: };



       7:  



       8: using namespace fastdelegate;



       9:  



      10: // 定义标准的事务参数



      11: class CEventArgs



      12: {



      13: public:



      14:     CEventArgs (void



      15:     {



      16:         bHandled = FALSE;



      17:     }



      18:  



      19:     BOOL    bHandled;



      20: };




    然后是定义一个事务句柄经管类:





       1: // 定义事务句柄,用于经管事务中参加的委托



       2: template <class TBase>



       3: class CEventHandlerBase



       4: {



       5: public:



       6:     virtual ~CEventHandlerBase ()



       7:     {



       8:         forint i = _delegates.GetSize () - 1; i >= 0; i --)



       9:         {



      10:              (TBase) _delegates[i];



      11:         }



      12:         _delegates.Empty ();



      13:     }



      14:&#160; 



      15:     size_t GetCount (void) { return _delegates.GetSize (); }



      16:&#160; 



      17:     // 添加委托



      18:     void operator += (TBase& eventDelegate)



      19:     {



      20:         _delegates.Add (new TBase (eventDelegate));



      21:     }



      22:&#160; 



      23:     // 删除委托



      24:     void operator -= (TBase& eventDelegate)



      25:     {



      26:         forint i = _delegates.GetSize () - 1; i >= 0; i --)



      27:         {



      28:             if (((TBase) _delegates[i]) == eventDelegate)



      29:             {



      30:                  (TBase) _delegates[i];



      31:                 _delegates.Remove (i);



      32:             }



      33:         }



      34:     }



      35:&#160; 



      36: public:



      37:     CStdPtrArray _delegates;



      38: };




    最后定义一个宏用于快速创建事务句柄:





       1: // 定义天务句柄的类 handleClass 为句柄类名称,eventClass 为参数类名称



       2: #define DEFINE_EVENT_HANDLER(handleClass, eventClass) \



       3:     typedef FastDelegate2<IEventSource , eventClass > eventClass##Delegate;\



       4:     class UILIB_API handleClass : public CEventHandlerBase<eventClass##Delegate>\



       5:     {\



       6:         public:\



       7:         void Fire (IEventSource sender, eventClass e)\



       8:         {\



       9:             forint i = _delegates.GetSize () - 1; i >= 0; i --)\



      10:             {\



      11:                 ((eventClass##Delegate) _delegates[i]) (sender, e);\



      12:             }\



      13:         }\



      14:     }



      15:&#160; 



      16: DEFINE_EVENT_HANDLER (CStdEventHandler, CEventArgs);




    应用如有两种景象,一是只用CEventArgs参数类型就可以满足请求,二是需扩大本身的参数类型。若是须要扩大参数,代码如下:





       1: class CMouseEventArgs : public CEventArgs



       2: {



       3: public:



       4:     CMouseEventArgs (MouseButtons button1, int clicks1, int x1, int y1, int delta1);



       5:&#160; 



       6:     MouseButtons button; int clicks; int x; int y; int delta;



       7: };



       8:&#160; 



       9: // void handler (IEventSource sender, CMouseEventArgs e);



      10: DEFINE_EVENT_HANDLER (CMouseEventDelegate, CMouseEventArgs);




    应用代码示例如下:





       1: class CGlobalWindowMsgHook : public IEventSource



       2: {



       3: private:



       4:     CGlobalWindowMsgHook (void);



       5: public:



       6:     ~CGlobalWindowMsgHook (void);



       7:&#160; 



       8:     static CGlobalWindowMsgHook instance (void);



       9:&#160; 



      10:     // 定义鼠标点击事务



      11:     CMouseEventDelegate MouseClick;



      12:&#160; 



      13:     ……



      14: protected:



      15:     static LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam, LPARAM lParam)



      16:     {



      17:         CGlobalWindowMsgHook This = instance();



      18:         PMSLLHOOKSTRUCT hookStruct = (PMSLLHOOKSTRUCT)lParam;



      19:         



      20:         int msg = wParam;



      21:         int x = hookStruct->pt.x;



      22:         int y = hookStruct->pt.y;



      23:         int delta = (short)((hookStruct->mouseData >> 16) & 0 xffff);



      24:         



      25:         if (msg == WM_LBUTTONUP)



      26:         {



      27:             // 触发鼠标点击事务



      28:             This->MouseDown.Fire (This, &CMouseEventArgs (Left, 0, x, y, delta));



      29:         }



      30:         ……



      31:     }



      32:     ……



      33: };



      34:&#160; 



      35: // 测试类



      36: class CTest



      37: {



      38: public:



      39:     CTest ()



      40:     {



      41:         CGlobalWindowMsgHook::instance()->MouseClick += MakeDelegate (this, &CTest::MouseDownHandler);



      42:     }



      43:     ~CTest ()



      44:     {



      45:         CGlobalWindowMsgHook::instance()->MouseClick -= MakeDelegate (this, &CTest::MouseDownHandler);



      46:     }



      47:&#160; 



      48:     void MouseDownHandler (IEventSource sender, CMouseEventArgs e)



      49:     {



      50:         printf (_T("hello"));



      51:     }



      52: }


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