event tables

[mikecoon]

According to the new wxWidget book, you should place the event table in the implementation file. Why is that? Because I all this time I always always placed the event table right after the class declaration in the header file and it always worked for me.

Is there a special reason to place your event table int he .cpp file?
mikecoon

[Ryan Norton]

Is there a special reason to place your event table int he .cpp file?
mikecoon

Yeah - the same reason you don't implement anything in a header - in complex projects you're gonna get linker errors.

Even with a header gaurd if you include the header in more than one cpp file you'll get a linker error doing so.

[ssigala]

Is there a special reason to place your event table int he .cpp file?
mikecoon

Because you should think the event table as a variable. Variables are never declared in headers files, because doing so will cause a linker error (multiple definitions).

[mikecoon]

Thank you. Now I understand. I moved the enums and the event table to the .cpp file now.

[upCASE]

Hi!
The enums can still reside in the header file. Use the enum inside your class.

[ssigala]

Hi!
The enums can still reside in the header file. Use the enum inside your class.

Good suggestion upCASE. Including the enums into the class definition also keeps the C++ namespace clean.

e.g.:

Code: Select all

class MyFrame: public wxFrame {
// ...
public:
    // IDs of children objects 
    enum {
        ID_BUTTON1,
        ID_MENU_ITEM1
    }
// ...
};

[bunter]

Also, there is a way to create only header file for a class and to make that class handle events.

This way event table macros are not used at all, and cpp file is not needed. Instead, dynamic event handling is used.

Code: Select all

class InHeaderEvtHandler : public wxEvtHandler
{
	wxTimer timer_;

	void Init()
	{
		timer_.SetOwner(this);
		timer_.Start(3000);
		Connect(wxTimerEvent().GetEventType(), wxTimerEventHandler(InHeaderEvtHandler::OnTimer));
	}
public:
	InHeaderEvtHandler() { Init(); }
	
	void OnTimer(wxTimerEvent& event)
	{
		wxMessageBox("InHeaderEvtHandler::OnTimer");
	}
};