Re: Gtk2-perl shell (problem with GLib-GObject)

[muppet <scott asofyet org>]

On Jan 11, 2005, at 7:40 AM, Remco Wouts wrote:

> I wrote a small Gtk2 shell. The attached code is the gist of it[1]. 
> You can do things like:
>  gish> Gtk2::Window->new->add(Gtk2::Button->new('foobar'))->show_all

nice choice of name.  :-)

have you seen
  http://asofyet.org/muppet/software/gtk2-perl/gish.html
or
  http://asofyet.org/muppet/software/gtk2-perl/gws.html
?

In gws, you can make perl refresh the implementation of a subroutine by 
highlighting the sub and hitting KPEnter, and ignoring the "subroutine 
redefined" message.


> This is handy enough. The main problem is that objects that have been 
> Glib::Object::Subclass'ed don't work very well.
>  1) You cannot reread such a package. Eg 'do LabelledButton.pm' gives:
> GLib-GObject-WARNING **: cannot register existing type 
> `LabelledButton' at 
> /usr/lib/perl5/site_perl/5.8.3/i686-linux/Glib/Object/Subclass.pm line 
> 225.

This warning comes from glib's type system, not from the bindings.  
It's in the private helper function check_type_name_I(), called by 
g_type_register_fundamental(), g_type_register_static() and 
g_type_register_dynamic() (the functions that register new GTypes).

The basic problem here is that when you register a type with glib, it 
remembers that type information until the program exits.  The type 
names must be unique, and you get this error if they aren't.

The workaround for this would be to use different type names every 
time.  It would be conceivable to have the bindings generate a new C 
type name for each package, but this is not desirable for several 
reasons:
a) you can't unregister GType types, so the old types would still be 
there, just waiting to cause problems.
b) mapping names names like Some::Package to Some-Package-4162 isn't 
very friendly, especially when you start getting error messages.

>  2) The subclassed widget itself does not work correctly ie. after the 
> first 'do' it loads but does not display correctly. It does display 
> correctly when you load modify 'gish' to load the package at startup.

What do you mean by "does not display correctly"?

What version of Glib are you using?  There's a bugfix in 1.060 related 
to late loading of Glib::Object::Subclass.


> [1] I abbrev'ed. it for clarity.

Could you send the whole thing?  The LabelledButton example worked fine 
in my version of gish-0.2, using Glib 1.061.


--
I don't have a drinking problem,
'cept when i can't get drink.
  -- Tom Waits