Re: Initialisation/Finalisation

[iain <iain prettypeople org>]

On Mon, 2002-11-04 at 12:18, John Darrington wrote:
> My Questions are: 
>
> 1. The Finalize func undoes the Init func.  Fair enough.  But why is
>    there no GInstanceFinalizeFunc?  See example below:

All objects I've ever written have had NULL for everything except the
GClassInitFunc and GInstanceInitFunc.

Actually I think I had one that had NULL for GInstanceInitFunc too once.
So basically, you don't need to worry about them.

> I have a gobject, whose _new function looks like :
>
> GObject* 
> pgc_new(const gchar *c)
> {
>   PGC *pg;
>
>   pg = PGC(g_object_new(TYPE_PGC,0));
>
>   g_assert(pg);
>
>   pg->info = g_strdup(c);
>
>   return G_OBJECT(pg);
>
> }
>
>
> Now the doco for g_strdup says that the pointer returned must be freed
> when no longer needed.  But how and when can I do that ??  It needs to
> be freed when the object is destroyed, but there is no
> GInstanceFinalizeFunc which (to me) would seem the logical thing to
> have.

Override either the dispose or the finalize methods of the GObjectClass

like so.

static void
finalize (GObject *object)
{
   PGC *pg;

   pg = PGC(object);
   
   g_free (pg->info);

  /* Other things here */
  
  /* Chain up to the parents finalize */
  G_OBJECT_CLASS (parent_class)->finalize (object);
}

/* And override the finalize method here */
static void
class_init (PGCClass *klass)
{
  GObjectClass *object_class;

  object_class = G_OBJECT_CLASS (klass);

  object_class->finalize = finalize;
}

Now whenever the object is destroyed, the memory will be freed.

iain
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 To snuff out the mind that moves"