Re: making a SCM from a GObject *

[gregory benison]

Peter Gavin wrote:

> Ok, so, I'm a bit new to guile, but I've been playing around w/ trying
> to embed guile in my app, and one thing I've been wanting to do is
> create a GObject subtype in C and pass it to some scheme code
I am a bit new to guile-gnome as well. 
I am also interested in doing what you are trying to do.
I think this is likely to be a common desire among people trying out 
guile-gnome.

> I
> couldn't find any docs concerning this, and google gave me no hits,
>  
I have had success using this method:
1) Create a .defs file which describes your gobject - based header 
file.  It describes all of your functions and custom types.  Look in the 
guile-gnome distribution in the 'defs' directory for examples.  You can 
use the 'h2defs.py' program (found in the guile-gnome distribution) to 
generate this file automatically from your headers, if you have followed 
normal conventions in writing your headers.
2) Process your .defs file to automatically create C-to-guile glue code 
for your gobject types.  Look at any "*-spec.scm" file in the 
guile-gnome distribution to see how this works.
3) Compile the resulting C file into a shared library.  Load it from a 
scheme interpreter, and your gobject type will be available to use from 
scheme.

( guile-gnome experts: is this the right approach?? )

I admit that the above method looks intimidating at first but it really 
does work,
and it allows you to use your C code from scheme with very little extra 
coding.
If you use the above method, you can use your gobjects seamlessly in 
scheme (subclassing from them, connecting signals to them, etc.)
I would be interested in writing some additional documentation for this...
in my opinion the guile-gtk and guile-gnome teams have made a really 
great programming environment here, and new users could benefit from 
some additional documentation, especially regarding C/guile 
interoperability issues.

> get back an error when I use it:
> <gtype> #<gtype GObject> already has a GOOPS class, use gtype->class
> Am I using the wrong function, or using it in the wrong way?
>  
I don't understand this approach very well, but I suspect it is not what 
you want.

Greg