Re: glib ref counting problem

[Stefan Kost <kost imn htwk-leipzig de>]

Hi Tristan,

Tristan Van Berkom wrote:
> Stefan Kost wrote:
>
> > hi hi,
> >
> > hope that someone can enlighten me with my understanding of the gobject
> > ref-counting regarding to object destruction.
> >
> > I have a gobject called BtSong. Upon construction it creates instances of
> > BtPattern, BtSetup and son on where it passes itself along.
> > Thus each child object now holds a reference to the BtSong object.
> > When the application that initialy created the BtSong instance is
> > done, it would
> > like to destroy the object with all the accosiated ressources. It
> > therefore
> > calles g_object_unref(song);.
>
>
> If BtSong is the "owner" of BtPattern and BtSetup, then BtSong should
> simply hold the initial reference on BtSetup and BtPattern (i.e. every
> object is "born" with a `ref_count = 1'. Thus in bt_song_finalize(),
> BtSong will release its reference on BtPattern and BtSetup, leading to
> their destruction.
Unrefing must be done in dispose as far as I know.
> If for example, BtPattern is needed after BtSong's
> destruction, then the code which requires its existance, should hold
> a reference to BtPattern and release it when it is no longer needed.
No, the child objects are not needed.

I will try to make it clearer.
application creates the BtSong
  BtSong->refct=1
the songs instance init creates the private BtPattern and BtSetup instances
and passes itself to their constructiors.
  BtSong->refct=3
  BtPattern->refct=1
  BtSetup->refct=1
the application is doe with the song (and everything that belongs to it), thus
calls g_object_unref(song);
  BtSong->refct=2
because that is unequal to 0, the dispose handler of BtSong is not called (and
neither finalize is) and therefore I can't release the refs to BtPattern and
BtSetup.

I hope it is clearer now.

Ciao
  Stefan
-- 
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