关于成员函数的Command模式的简单实现
看到Fox发表关于成员函数的消息映射的文章，也忍不住发表的一点自己的观点，希望对大家有所帮助。
其实也就是COMMAND模式的简单实现，看代码吧。
- XGUIEventHandlerPointer.h
{
class EventHandlerSlot
{
public:
virtual ~EventHandlerSlot() {};
virtual void execute(const EventArgs& args) = 0;
virtual void* getClass() = 0;
};
template
<typename T>class EventHandlerPointer :
public EventHandlerSlot
{
public:
typedef
void (T::*EventHandler)(const EventArgs&);public:
EventHandlerPointer() :
d_undefined(
true), d_object(NULL)
{}
EventHandlerPointer(EventHandler func, T
* obj) : d_function(func),
d_object(obj),
d_undefined(
false) {}
virtual ~EventHandlerPointer() {}
void execute(const EventArgs& args)
{
if(!d_undefined)
(d_object
->*d_function)(args); }
void* getClass()
{
return static_cast<void*>(d_object);
}
protected:
EventHandler d_function;
T
* d_object;bool d_undefined;
};
}
- XGUIWidget.h
{
//
class Widget
{
public:
template
<typename T> void addWidgetEventHandler(WidgetEvent EVENT, void (T::function)(const EventArgs&), T obj) {
mWidgetEventHandlers[EVENT].push_back(
new EventHandlerPointer<T>(function,obj)); }
void addWidgetEventHandler(WidgetEvent EVENT, EventHandlerSlot* function)
{
mWidgetEventHandlers[EVENT].push_back(
new EventHandlerPointer<T>(function,obj)); }
bool Widget::fireWidgetEvent(WidgetEvent EVENT, EventArgs& args)
{
// If there are no User defined event handlers we are done.
if(mWidgetEventHandlers[EVENT].empty())
return false;
// Execute registered handlers
std::vector<EventHandlerSlot> userEventHandlers = &(mWidgetEventHandlers[EVENT]);
for(std::vector<EventHandlerSlot*>::iterator it = userEventHandlers->begin(); it != userEventHandlers->end(); ++it )
(
*it)->execute(args);
return true;
}
// .
};
}
以上只为部分代码。