Re: [gtkmm] adding a widget to a container

[cedric <cedric probesys com>]

Max Vasin a écrit :

> Ainsley Pereira wrote:
>
> > Hi again,
> >
> > I'm not quite sure I follow your description, but there are a couple of
> > things I can point at for you to investigate further:
> >
> > On Mon, May 03, 2004 at 06:00:26PM +0200, cedric wrote:
> >  
> >
> > > so to do this, i ve 2 ptr declared in my Plugin.hh file
> > >   static Gtk::HBox *toolBarModContainer_ptr;
> > >   static Gtk::Toolbar *toolBarModDisplayed_ptr;
> > >   
> >
> >
> > If you declare a static, it's visible only to that translation unit
> > (think of this as the .cc file and all the files it #includes). Putting
> > a static in a .h file is almost always the wrong thing to do - if two
> > .cc files include it, you end up with TWO copies of the variable, both
> > with the same name, but not the same variable. If you're including
> > Plugin.hh from two different .cc files, and setting the variable in one,
> > but using it in the other, you're not setting the same variable.
> >  
>
> you probably want to declare them `extern'

i have already tried, but i have a compilation error (undefined 
references to the pointers) when i remove the static keyword in 
Plugin.hh. if i let the pointers static, then i have a segfault probably 
due to the multiple variables with the same name (instead one global 
variable) like Ainsley said. Anyway, i ve never managed to use correctly 
the extern keyword (but maybe i didn t try enough). that s why i m out 
of ideas! :-/

> > (General hint: Always initialise pointers at declaration. If you can't
> > give them their final value yet, initialise them to 0. If you do that
> > here, you can at least verify whether what I've described above is
> > what's happening in your code, by checking if it's still 0 before you
> > use it.)
> >  
>
> And another hint:
> It is a good idea to use smartpointers that will check if the pointer 
> isn't 0
> and report when you try to dereference a null pointer.
>  

ok, i ll try it too!