Re: Interaction between GTK+ and C++

[Jeff Franks <jcfranks tpg com au>]

Brian Hanley wrote:

> Hi,
>
> Has anyone tried to wrap GTK+ in C++ without using GTKmm?
>  
Yes, I have.

> That is, making calls to GTK’s C-language API from C++ objects?
> If so, has anyone documented the paradigms/techniques/gotchas,
> or published sample code?
>  
This CVS link contains the object code you are interested in, in 
<gfc/glib/object.[cc, hh]>
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/gfc/gfccore

This CVS link contains the GTK GUI code
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/gfc/gfcui

> Specifically, how does one manage the lifespan of interdependent
> widgets and C++ objects? Is it feasible to have both event-driven
> GTK callbacks which reference C++ objects and externally-driven
> calls to the C++ objects which reference these same widgets?
> How does one manage the lifespan of such objects and widgets?
>  
The correct way is to let GTK manage the life span of your C++ object. 
When GTK notifys you that the wrapped C object has been destroyed you 
call delete on its C++ wrapper. Have a look at the G::Object constuctor 
and the G::Object::destroy_notify function in <gfc/glib/object.[cc, hh]>.

> For example, an instance "obj" of class "MyWrapper" contains
> a pointer to a widget "widg", and the address of "obj" has
> been passed as a user-data argument to a GTK signal handler
> for "widg".
>
> How might one manage the lifespans of "obj" and "widg" given
> that someone could both (i) call "delete" on "obj", and
> (ii) call "gtk_widget_destroy" on "widg"?
>
> Is it just a bad idea to try to mix event-driven code with
> external triggers?
>
>  
It's not possible to answer your questions in just a few lines because 
the answers are not simple. You should find what your looking for though 
at the CVS links above. If you have any questions about my code, just 
ask me. I hope you have a good reason for wanting to write your own C++ 
wrapper for GTK+ because I can assure you, it will take a lot of 
committent and a lot of hours, and a lot hours, and a lot hours...

Regards,
Jeff.