Re: g_object_add_toggle_ref

[Emmanuele Bassi <ebassi gmail com>]

Hi Stefan;

I very much doubt anybody here has knowledge of toggle reference and
language bindings.

You want gtk-devel-list gnome org, or you want to join the #gtk+ IRC
channel on irc.gnome.org.

As a note, though:

> But when the user creates widgets and never add them to a container, there state
> remains ref count 2 floating

All GC language bindings will immediately sink the floating reference,
as it makes memory management harder for them (it's a C feature, after
all). So my suggestion is to immediately and automatically sink the
floating reference inside your wrapper around g_object_new() before it
returns the instance to the non-C side.

Ciao,
 Emmanuele.

On 25 June 2017 at 10:38, Stefan Salewski <mail ssalewski de> wrote:
> On Tue, 2017-06-06 at 14:33 +0200, Stefan Salewski wrote:
> > so after call of g_object_add_toggle_ref() ref_count is indeed 2, and
> > after call of g_object_unref() the toggleNotify() callback is
> > activated.
>
> Some more investigations seems to indicate:
>
> When I create a widget and apply g_object_add_toggle_ref(), then ref
> count is increased to 2 and the widget is still floating, When I now
> add that widget to a container, object is sunk, ref count stays at 2,
> and the toggle ref callback in not yet called. But when I remove the
> widget from the container again, ref count decreases to 1, and the
> toggle ref callback is called. This is fine, as the callback can now
> decrease refcount of the proxy object as well. Adding that widget to
> the container again works also, callback is called...
>
> But there is one drawback: In GC languages the user is generally free
> to create a large number of object and just forget about them. But when
> the user creates widgets and never add them to a container, there state
> remains ref count 2 floating, and they are keep alive until program
> terminates.
>
> Well, we may say that the user should not do that, because it makes no
> sense.
>
> A possible fix would be to fake a conainer add/remove operation. I can
> do that by a ref_sink/unref function call on the widget after call of
> g_object_add_toggle_ref(). That results in a ref count of 1 and a not
> floating object, which behaves fine futher. But I am not sure if I
> should do that fake, maybe it again generates other problems.
>
>
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