Re: Widget ref-count on creation

[Russell Shaw <rjshaw netspace net au>]

Tristan Van Berkom wrote:
> Russell Shaw wrote:
>
> > so i assume this increases the refcount to 2 (couldn't tell
> > by looking at gtk source). So, if the containing window is
> > destroyed, it will release its refcount. However, the ttt
> > widget will still have a refcount of 1 and hang around.
> >
> > What is the correct way of handling the refcount on widget
> > creation?
>
>
>     I believe that at some point in time (gtk+-1.2 ==> gtk+-2.0 I think)
> that this behaviour was changed, in the prior; the correct process was to:
>
> // create widget
> my_widget = g_object_new(MY_OBJECT_TYPE, NULL); // <-- refcount 1
>
> // add to a container
> gtk_container_add(container, my_widget); // <-- refcount 2
>
> // pass ownership to the container
> g_object_unref(my_widget);               // <-- refcount 1
>
>
> But since then (because that code seemed redundant or encumbersome),
> GtkObject and its subclasses are created with what is called a floating
> reference, which in turn is unreferenced by the container implementation
> by calling gtk_object_sink(); (after the container takes ownership of
> the GtkObject by calling g_object_ref(); )
>
> So any GtkObject at creation time has no "owner".

Ok, i think some clarifications are needed in the docs.

From: http://developer.gnome.org/doc/API/2.0/gtk/GtkObject.html

  The most interesting difference between GtkObject and GObject is the
  "floating" reference count. A GObject is created with a reference count
  of 1, owned by the creator of the GObject. (The owner of a reference is
  the code section that has the right to call g_object_unref() in order to
  remove that reference.) A GtkObject is created with a reference count of 1
  also, but it isn't owned by anyone; calling g_object_unref() on the
  newly-created GtkObject is incorrect. Instead, the initial reference count
  of a GtkObject is "floating".


This implies that GtkObject is created differently to GObject. However, in
gtkobject.c, gtk_object_new() simply creates a GObject.

So, the above explanation about floating references is really only a
matter of notation, because the floating reference is stored as a
"normal" reference.