Re: Signal handler args

["Rudy Albachten" <rudy albachten amd com>]

If I'm not positive something is an object, instead of:
    if (defined $arg2 and $arg2->isa("Gtk2::Gdk::Event")) {
    }
I use:
    if (UNIVERSAL::isa($arg2, "Gtk2::Gdk::Event")) {
    }
This returns false if $arg2 is undefined or isn't a reference.

The first example fails if $arg2 = 10 (any scalar value) or
if $arg2 = \10 (an unblessed reference).
    
If I made the object and it was never out of my code (kind of like
luggage never being out of my control), I the first, if the user
(other programmer) handed me the object or had a chance to manipulate
it, I use the latter.


On Tue, Oct 22, 2002 at 09:38:04AM +0200, goran kirra net wrote:
> Dermot,
>
> I not too happy about the syntax myself,
> but the behavior is consistent with how it is done in C
> and probably in old gtk-perl(?)
>
> The reason probably is that these signalhandlers are
> most often different kind of beast.
> You should be able to test the second arggument with
> something like (untested code follows):
>
> if (defined $arg2 and $arg2->isa("Gtk2::Gdk::Event")) 
> {
> ...
> }
>
> I am willing to change this in line with your
> suggestion if we can reach consensus.
>
> /g?ran
>
> On Tue, Oct 22, 2002 at 04:11:32AM +0100, Dermot Musgrove wrote:
> > Hi all,
> >
> > Following a previous thread, I tried to connect a signal handler to
> > 'button_press_event' and was delighted that it worked - however ...
> >
> > In the event handler, 'print Dumper(\ _)' produces:
> > (I passed {'data'=>'test data'} to the data arg of signal_connect)
> > $VAR1 = [
> >           bless( do{\(my $o = 137040016)}, 'Gtk2::Button' ),
> >           bless( do{\(my $o = 137239944)}, 'Gtk2::Gdk::Event' ),
> >           {
> >             'data' => 'test data'
> >           }
> >         ];
> >
> > Please can we have the args to the signal handlers delivered as:
> >
> >   my ($widgetref, $dataref) = @_;
> >
> > or for an event handler
> >
> >   my ($widgetref, $dataref, $eventref) = @_;
> >
> > At least this way, it is possible to write generic handlers that do
> > not need to know whether the handler is connected to a signal or an
> > event in order to work. It also makes it possible to auto-generate
> > simple signal handlers for programmers to edit (Glade-Perl-Two will 
> > do this so I have an interest :-)
> >
> > I don't know if it is simple to translate the Gtk2::Gdk::Event into
> > an anonymous hash and pass that to the handler as Gtk-Perl does but 
> > IMO that is any easier thing to use and understand.
> >
> > Regards, Dermot
> >
> > _______________________________________________
> > gtk-perl-list mailing list
> > gtk-perl-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gtk-perl-list
>
> -- 
> G?ran Thyni
>  Senior Technical Consultant
>  SchlumbergerSema
>  Lule?, Sweden
>
>
> _______________________________________________
> gtk-perl-list mailing list
> gtk-perl-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtk-perl-list

-- 
   Rudy Albachten
   Advanced Micro Devices
   Athlon Design Team
   Texas Microprocessor Division
   Austin, Texas