Hans, i haven't read all you wrote, but from what i read i think you
can solve the problem by using toggle_ref. It was a new API that was
added to GObject on the lastest release, exactly to solve binding
issues.
There was a long dicussion about this on java-gnome-hackers, and now
Java-Gnome uses that toggle_ref API. It also does some other tricks to
solve other memory management "problems".
Cheers,
J.V.
2005/11/16, Hans Oesterholt-Dijkema <hdnews@xxxxxxxxx>:
>
>
> Why would a garbage collector be in any way interested in a resource
> that was not explicitly allocated by the calling application code ?
> It's not. My goal is to never have to use "g_object_unref" from scheme.
> The GC can do that for me. However, I also do not want gobjects to
> be prematurely destroyed.
>
> So what I do, as can be seen from the code sample 3, is, a GObject
> proxy scheme object takes ownership of all GtkObjects and GObjects
> that it gets to see.
>
> You can see this overtaking of ownership in code sample 3. The
> decision procedure for taking over ownership for GtkObjects is
> obvious. When I floats, mzgtk2 takes ownership. When a GtkObject
> is added to a container, the reference count will increase. When
> the scheme object associated with it goes out of scope in scheme,
> the GC will clean up the proxy object, and while cleaning up, the
> reference count to the GtkObject is decreased. However, because
> the GtkObject had previously been added to a container, the container
> will be the last one (seen from the Gtk world) to have a reference
> to the GtkObject.
>
> With GObjects it is more difficult. They are not floating. It is
> impossible to detect, weather it has been created by some Gxyz_new()
> call, or as part of an other structure. When creater by some Gxyz_new()
> call, the code in code sample 3 does it's job right. By not increasing
> the reference count of GObjects with ref_count 1, it takes ownership
> of the GObject. However, this doesn't hold for GObjects that
> are already owned by an other GObject, as is the case for a GtkImage
> with a GdkPixbuf created from file.
>
> Now, what happens if I do nothing while accessing the GdkPixbuf of
> a GtkImage (e.g., to set an icon with gtk_window_set_icon())?
>
> Because the ref. count of the GdkPixbuf = 1, mzgtk2 will take owenership
> of it, by not increasing the reference count. Now the GdkPixbuf is owned
> by the GtkImage and mzgtk2. And there it goes wrong. I hand the GtkPixbuf
> over to the gtk_window (using gtk_window_set_icon()). The reference
> count to the GtkPixbuf is increased to 2 by that call. Next, the GdkPixbuf
> goes out of scope in scheme. The reference count drops to 1. Next, the
> GtkImage (which was created within some scope and is no longer necessary)
> goes out of scope, and the reference count drops to 0. What the..., now
> the GdkPixbuf is cleaned from memory, while still in use by the GtkWindow.
>
> Ok, I need some decision procedure to determine if I get a GObject that
> is already owned or if I get a *new* GObject.
>
> Still following? More to follow beneath the code sample.
>
>
>
>
> ===========================================
> if (GTK_IS_OBJECT(g)) {
> if (GTK_OBJECT_FLOATING(g)) {
> g_object_ref(g);
> gtk_object_sink(g);
> }
> else {
> g_object_ref(g);
> }
> }
> else if (gobject_ref_count(g)>1) {
> g_object_ref(g);
> }
> ===========================================
>
> May I ask why you aren't referencing objects that
> have a ref_count of "1" and why you are not adding
> a reference to floating GtkObjects ?
> So, that's to take ownership of these Objects, so that the
> Garbage Collector can do it's normal cleaning job.
>
>
> I obviously dont know enough about your project to solve
> your problem, but I hope this was helpfull anyway.
> Best whishes and thanks,
>
> Hans Oesterholt-Dijkema.
>
>
>
> Cheers,
> -Tristan
>
>
>
> _______________________________________________
>
> gtk-list@xxxxxxxxx
> http://mail.gnome.org/mailman/listinfo/gtk-list
>
>
>
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