Re: Using (or not using) sigc::mem_fun with the G_CALLBACK macro

[John Taber <jtaber johntaber net>]

Paul,
thks for the code outline.  I have also been struggling with using a gtk 
widget in my gtkmm code.  Unless there is another demo somewhere that I have 
not seen, maybe this code could be cleaned up a bit with comments, etc to 
have a nice clear demo of a gtk widget being wrapped and instantiated and 
having it's signal picked up by a  gtkmm slot function.  This would be really 
useful and also make a great addition to the gtkmm tutorial.  
John

On Thursday 16 June 2005 05:50 am, Paul Davis wrote:
> On Thu, 2005-06-16 at 06:08 -0500, Bob Caryl wrote:
> > Murray Cumming wrote:
> > >And if you must provided a C function pointer, you'll need to provide a
> > >pointer to a static method (or global function) and the state
> > >information as user_data. See the various SignalProxy classes, for
> > >instance, in TreeSelection.
> >
> > In other words, the way I've done it (separate executable invoked via
> > fork, execv) is the only thread safe way to do this until GtkHTML has a
> > C++ wrapper.
>
> what are you thinking? this has nothing to do with threads. it doesn't
> even have a *lot* to do with language, except for the fact that you
> can't use a non-static C++ member function as a C callback. if you
> really want to use C++ objects with GTK widgets, then do this:
>
> 	class Foo {
>             public:
> 	       static gint my_c_proxy_for_bar (arglist...);
> 	       gint my_handler_for_bar (otherarglist...);
>         };
>
> 	gint
>         Foo::my_c_proxy_for_bar (..., gptr user_data, ...)
>         {
> 	    return reinterpret_cast<Foo*>(user_data)->my_handler_for_bar
> (relevant_args...);
> 	}
>
> 	gint
> 	Foo::my_handler_for_bar (otherarglist...)
> 	{
> 	}
>
> and then somewhere, connect
>
> 	gtk_signal_connect (widget, "signal", ...., SomePtrToFoo);
>
> I have done this a lot with the GtkCanvas widget which has never been
> wrapped for C++ (and never will be; we're migrating to GNOME::Canvas
> ASAP)
>
> --p
>
>
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