To the wonderful wizards of Vala... I need some help... I have an
object that presents certain information in a dialog. Other instances
of that object also share the same dialog. Nothing else in the program
needs to know that the Dialog even exists, it will manage its own
lifetime.
I assume the following two issues are simply that I just don't
understand how to tell Vala about my intentions regarding object
ownership... Starting with the line:
new EventNotifier(this,
new Gtk.TreeRowReference(store, store.get_path(iter)));
Unfortunately, this doesn't work.
- How to create an instance EventNotifier, without keeping a reference
to it (its lifetime is tied to a dialog which the caller doesn't
know about). That line fails because it's not being assigned to a
variable, and assigning it to a temporary variable results in this
error: "local variable 'blah' declared but never used"
- How to create and pass ownership of a Gtk.TreeRowReference to another
object. Gtk.TreeRowReference is a "compact class", if I understand
Vala terminology, and Vala seems to insist on wanting to copy the
instance. All I want to do is create it using local knowledge, and
then hand it off. No copying, no unref'ing, just pass a pointer.
I've looked at the source produced by Vala, and it seems to do an
incredible amount of temporary variable fiddling. For instance, one
that's been bugging me that I can't seem to work around;
Gtk.TreeIter iter;
events.store.get_iter(out iter, rowref.get_path());
The second line gets wrapped with freaky temporary variable magic. It
creates a temporary variable, stores the iter into that, then if the
original iter is not null, free's it (it'll ALWAYS be null here), and
then assigns the iter stored in the temporary variable into iter. I
can't remember if it was this instance, or another one, but I beleve
all that to, only happens if the temporary variable wasn't set to
null by get_iter(), which I also already know is not possible in the
context of that line anyhow.
Or is the C compiler supposed to recognise this situation and optimise
out all that temporary variable fussing? Or is there another way to
use an out parameter like that which is more informative to Vala, so
that it can simply pass the address of the iter and be done with it.
--
Fredderic
Debian/unstable (LC#384816) on i686 2.6.29-2-686 2009 (up 1 day, 16:21)
Attachment:
signature.asc
Description: PGP signature