Re: Removing Widgets From Gtk::Table

[Paul Davis <pjdavis engineering uiowa edu>]

Murray Cumming wrote:

> > > I've had a similar problem.  IIRC, I fixed it by removing things from
> > > the
> > > Gtk::Table object directly, via Gtk::Table::remove, rather than from the
> > > auxiliary Table_Helpers::TableList one.  Try it.
> > >      
> > That did the trick, thanks!
> >
> > Having said that though, does that mean that the
> > Table_Helpers::TableList interface just doesn't work?
> >    
>
> All API is meant to work.
>
>  
>
> > Or was it just
> > never intended to be used in the manner I was attempting (using the
> > Table_Helpers::TableList::iterator to remove specific widgets from a
> > table).
> >
> >    
>
> Probably, yes. A very simple compileable test case would be helpful.
>  
I'm gonna disagree on this one.  After doing a couple minutes of 
reading, I don't think that child modifications are meant to be done on 
the list returned by children.  Very few api's that I know of present 
live lists like that.

Now, the only thing I'm not sure about is the m4 macro that looks like 
the implementation for Gtk::Table::children().

I'm guessing, that its wrapping gtk_container_get_children() in gtk.

The docs for this are at:
http://developer.gnome.org/doc/API/2.0/gtk/GtkContainer.html#gtk-container-get-children

Anyway, if you go and look at the implementation for this function, it 
uses gtk_container_foreach()
Docs at:
http://developer.gnome.org/doc/API/2.0/gtk/GtkContainer.html#gtk-container-foreach

Anyway, the call back for the call to foreach is:

static void
gtk_container_children_callback (GtkWidget *widget,
                gpointer   client_data)
{
 GList **children;

 children = (GList**) client_data;
 *children = g_list_prepend (*children, widget);
}

Notice its copying the list.  Hence, no live back end, and therefore, no 
delete by removing and object from the list.

Granted, I haven't fully traced this out, but I'm fairly certain thats 
how things are working here.  A quick check would be delete something 
from the list, get the list again and see if it shows up.

#m4 directives are crazy by the way.  Granted they probably help quite a 
bit for wrappers like Gtkmm.  But, really, thats pretty crazy.

Paul

> Murray Cumming
> murrayc murrayc com
> www.murrayc.com
> www.openismus.com
>
> _______________________________________________
> gtkmm-list mailing list
> gtkmm-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtkmm-list
>
>