fetching unset GParamSpec property

[Kevin Ryde <user42 zip com au>]

The program below gets some errors followed by a segv

    GLib-GObject-CRITICAL **: g_param_spec_ref: assertion `G_IS_PARAM_SPEC (pspec)' failed at /home/gg/bug/default-value/param-null.pl line 19.
    GLib-GObject-CRITICAL **: g_param_spec_sink: assertion `G_IS_PARAM_SPEC (pspec)' failed at /home/gg/bug/default-value/param-null.pl line 19.
    GLib-GObject-CRITICAL **: g_param_spec_get_name: assertion `G_IS_PARAM_SPEC (pspec)' failed at /home/gg/bug/default-value/param-null.pl line 19.

I guess newSVGParamSpec() expect NULL.  Is it meant to?  Or is it up to
_gperl_sv_from_value_internal(), per below?

Maybe nobody ever used a paramspec property before. :-)  I can't think
what it'd be for.  An object factory object thing maybe.


-- 
"The only problem with Italian food is that 4 or 5 days later you start
feeling a bit peckish again."


package MyThing;
use strict;
use warnings;
use Glib;

use Glib::Object::Subclass
  Glib::Object::,
  properties => [ Glib::ParamSpec->param_spec ('myprop', 'myprop',
                                               'Blurb.',
                                               'Glib::Param::Boolean',
                                               Glib::G_PARAM_READWRITE) ];

package main;
use strict;
use warnings;
use Data::Dumper;

my $obj = MyThing->new;
my $x = $obj->get ('myprop');
print Dumper($x);

exit 0;

--- GValue.xs	10 Jan 2008 09:50:05 +1100	1.22
+++ GValue.xs	23 Jun 2008 17:49:34 +1000	
@@ -244,7 +244,16 @@
                                                  FALSE);
 
 		case G_TYPE_PARAM:
-			return newSVGParamSpec (g_value_get_param (value));
+			/* can have NULL here fetching object properties of
+			   type G_TYPE_PARAM with no value set yet, or from
+			   ->get_default_value of such a property */
+			{
+				GParamSpec *ps = g_value_get_param (value);
+				if (ps == NULL)
+					return &PL_sv_undef;
+				else
+					return newSVGParamSpec (ps);
+			}
 
 		case G_TYPE_OBJECT:
 			return gperl_new_object (g_value_get_object (value), FALSE);