Re: menuitem confusion

[Dave M <dave nerd gmail com>]

On Sun, Jul 1, 2012 at 6:10 AM, Torsten Schoenfeld <kaffeetisch gmx de> wrote:
> On 30.06.2012 21:53, Dave M wrote:
> > sub Gtk3::RadioMenuItem::new {
> >          my ($class, $group) = @_;
> >
> >          return Glib::Object::new( $class, group => $group );
> > }
> >
> > This returns
> > (radiomenuitem.pl:29742): Gtk-CRITICAL **:
> > gtk_radio_menu_item_get_group: assertion `GTK_IS_RADIO_MENU_ITEM
> > (radio_menu_item)' failed
>
>
> Note that the assertion refers to gtk_radio_menu_item_get_group.  It is due
> to the "group" property officially being of type GtkRadioMenuItem. So in the
> Glib::Object::new call above, Glib will create a GValue of this type
> containing NULL.  But under the hood, GtkRadioMenuItem actually accepts a
> list for the "group" property.  Here's the relevant code:
>
>   if (G_VALUE_HOLDS_OBJECT (value))
>     slist = gtk_radio_menu_item_get_group ((GtkRadioMenuItem*)
>               g_value_get_object (value));
>   else
>     slist = NULL;
>   gtk_radio_menu_item_set_group (radio_menu_item, slist);
>
> So it uses G_VALUE_HOLDS_OBJECT, which is always true when Glib constructed
> the value, to decide whether the value is a single item or a list.  In the
> former case, it doesn't handle NULL/undef gracefully -- this is where the
> assertion occurs.
>
> I think the following would work better, given the above constraints:
>
>
>   sub Gtk3::RadioMenuItem::new {
>     my ($class, $group) = @_;
>     $group = [] unless defined $group;
>     return $class->new ($group);
Thanks for the explanation.  However, when I do things like this,
there are recursion warnings.  Isn't that calling itself?  Happened
when I did something similarly with "new_with_label" too recently.

Thanks,
Dave M