Re: buildable interface testers error

[Torsten Schoenfeld <kaffeetisch gmx de>]

Kevin Ryde wrote:
> > So I think you'll have to do some version checking with Gtk2->CHECK_VERSION.
>
> Is there a direct way to ask if something is an implementable interface?
> I guess Gtk2::Buildable->can('_ADD_INTERFACE'), but if that's supposed
> to be used.

That's relying too much on internals, I think.  Better ask Glib directly:

  grep { $_ eq 'Gtk2::Buildable' } Glib::Type->list_interfaces ('Gtk2::Widget')

Or maybe even better yet, ask perl:

  Gtk2::Widget->isa ('Gtk2::Buildable');

> > Or should the bindings behave differently in such a case?
>
> The error message is fairly obscure.  But an error from
> Glib::Object::Subclass is probably good.  For myself I'll want to
> quietly drop Buildable when not available, but for other interfaces that
> could be bad.

We could check that the interface is actually registered before calling 
_ADD_INTERFACE, as in the attached patch.  Does this make sense?  muppet?

-Torsten

Index: GType.xs
===================================================================
--- GType.xs    (revision 1033)
+++ GType.xs    (working copy)
@@ -1458,10 +1458,18 @@ add_interfaces (GType instance_type, AV 
                newSVpv (gperl_object_package_from_type (instance_type), 0);
 
         for (i = 0; i <= av_len (interfaces); i++) {
+               GType interface_type;
+
                SV ** svp = av_fetch (interfaces, i, FALSE);
                if (!svp || !gperl_sv_is_defined (*svp))
                        croak ("encountered undefined interface name");
 
+               interface_type = gperl_object_type_from_package (SvPV_nolen (*svp));
+               if (!interface_type) {
+                       croak ("encountered unregistered interface %s",
+                              SvPV_nolen (*svp));
+               }
+
                /* call the interface's setup function on this class. */
                {
                        dSP;