Re: GnomePixmap vs. the old gnome_create_* functionality

[Vollmer Marius <mvo zagadka ping de>]

Tom Tromey <tromey@creche.cygnus.com> writes:

> Quartic> I am thinking that all the Gnome widgets should be put into
> Quartic> the .defs file for the guile-gnome part...
> 
> I looked at this the other night, when I wrote gnome.defs.
> 
> The problem is that many Gnome widgets use capabilities that can't be
> expressed in the .defs file.  For instance neither arrays of strings
> nor GLists can be handled.

That's right.  Another important thing missing is `pass by reference'
parameters.

But now that people have more experience with CORBA: Is it possible to
use CORBA for C<->Scheme interfaces?  Without rewriting the existing C
API of gtk?.

> Too bad the gtk.defs/gen-typeinfo rewrite disappeared.

Hmm, I'm not aware of any actual rewrite.  There were some more or
less concrete ideas floating around but none of them really
materialized, as far as I know.  I can probably dig them out of my
mail archives, but the larger part of it sits on a dial-up box that is
out of my reach right now.  But I think Tim posted the results to the
gtk-list.

> It might be possible to add the missing features without a huge
> rewrite.  I haven't investigated that, either.

It shouldn't be too bad.  Arrays can certainly be handled, we just
have to extend gen-typeinfo's idea of types.  For example
`(counted-array string)' could mean a char**,int pair where the int
holds the number of elements of the array. `(zero-terminated-array
strings)' could mean a single char**, where the last element of the
array is NULL. Etc.

Things are more complicated with GLists.  The elements of a GList are
untyped void* pointers, but we need to attach types to them.  Very
likely, there are no heterogenous lists in gtk or gnome, so we can
attach a single type to all list elements.  `(dlist GtkListItem)',
`(slist GtkRadioButton)'.

And we must be aware that these arrays and lists do not retain their
identity when they travel thru interpreter land.  That is

    (gtk-radio-button-new (gtk-radio-button-group rb))

will not work right, most likely.  Oh no, I just checked the source
and it seems that it *will* work.  Nice!

Inout parameters are difficult for Guile because we don't yet have a
way to return multiple values.  But R5RS is out now (I haven't had a
look), and we can just implement what they say about multiple return
values.

Ok, and then there is the problem with memory management.  Who owns
the array/list?  But that should be solvable, too.

Just some random thoughts...

Marius