Re: Equivalent of the gtk g_object_ref/unref functions in gtkmm?

[Jef Driesen <jefdriesen hotmail com>]

Murray Cumming wrote:
> On Thu, 2007-03-22 at 16:49 +0100, Jef Driesen wrote:
> > When I look at some gtk C code, I see everywhere pointers to widgets 
> > (and other things). As i understand all gtk objects are reference 
> > counted to keep the objects alive until the last pointer is released.
> >
> > How does that work in gtkmm? At first sight, gtkmm widgets doesn't seem 
> > to be reference counted, because something like this does not work 
> > (because of the private copy constructor):
> >
> > Gtk::Button a, b(a);
> >
> > Do I need to use smart pointers (e.g. boost::shared_ptr) for that? Does 
> > that means the underlying gtk reference counting mechanism is not used 
> > in gtkmm?
> >
> > I read in the gtkmm documentation there is a Glib::RefPtr, that uses the 
> > internal gtk/gobject reference counting. If I understand that correctly, 
> > I can use this smart pointer (instead of third party implementation like 
> > boost)?
> >
> > Glib::RefPtr<Gtk::Button> a(new Gtk::Button()), b(a);
> >
> > But I've never seen that before, only with non-widgets objects like 
> > pixbufs and treemodels.
>
> RefPtr is not for use with widgets. Widgets (or other things that derive
> from GtkObject rather than GObject) have different, more complicated
> memory management than the reference-counted objects such as TreeModel. 
>
> This page has an overview of gtkmm memory management:
> http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch22.html
>
> In summary, it's just regular C++ memory management so you can do what
> you like, and we have some things to help you sometimes.

Thanks for the clarification.

> > One of the problems I'm trying to solve is I want to create a treeview 
> > that will act as a sidebar pane in my application. And I would like to 
> > store a reference to other widgets (which are in a notebook) in the 
> > treemodel. When the user activates an item in the treeview, the 
> > corresponding widget should be displayed in the main application pane 
> > (by displaying the correct notebook page). How should this treemodel 
> > look like in gtkmm? Is a smart pointer going to interfere with the 
> > automatic memory management when I add the widget to the notebook? Do I 
> > need smart pointers at all for all this?
>
> You can use some other smartpointer, such as one from boost, or you can
> use some parent-child relationship of your own.

What do you mean with "parent-child relationship"?