Re: Problem with subclassing with Glib::Object::Subclass and Gtk3

[Yuri Myasoedov <ymyasoedov yandex ru>]

10.04.2015, 17:09, "Yuri Myasoedov" <ymyasoedov yandex ru>:
> I've tried to fix Gtk-3.0.gir and rebuilt it with g-ir-compiler. I added "allow-none" to vfuncs 
> "signal_changed", "style_set" and then I got a segfault on method "adjust_size_request". I've attached full 
> backtrace if it could help to locate the issue.
> But I still can't understand, why I need to reimplement methods PARENT_SET, HIERARCHY_CHANGED, EVENT, 
> otherwise my code fails with an error like "Can't locate object method "PARENT_SET" via package "MyButton" 
> at /usr/local/lib/x86_64-linux-gnu/perl/5.20.1/Glib/Object/Introspection.pm line 58". Something is wrong 
> with that.

I've fixed it.

The bug was in Glib::Object::Introspection module. If file 
perl-Glib-Object-Introspection/gperl-i11n-vfunc-object.c:

...
/* If there is no implementation of this vfunc at INIT
 * time, we assume that the intention is to provide no
 * implementation and we thus skip setting up the class
 * struct member. */
HV * stash = gv_stashpv (target_package, 0);
GV * slot = gv_fetchmethod (stash, perl_method_name);
if (!slot) {
    dwarn ("skipping vfunc %s.%s because it has no implementation\n",
        g_base_info_get_name (info), vfunc_name);
                g_base_info_unref (vfunc_info);
                g_free (perl_method_name);
                continue;
        }
}
...

But "gv_fetchmethod" is just a macro for "gv_fetchmethod_autoload":
#define gv_fetchmethod(stash, name) gv_fetchmethod_autoload(stash, name, TRUE)

That doesn't allow us to find non-implemented vfuncs. After replacing "gv_fetchmethod" with 
"gv_fetchmethod_autoload":
GV * slot = gv_fetchmethod_autoload (stash, perl_method_name, FALSE);

my code starts to work properly! I don't need to implement HIERARCHY_CHANGED, PARENT_SET and other 
non-implemented vfuncs.
I would like to ask Torsten or Brian to confirm this problem and review my improvement.