[Ecls-list] Lisp callback from C

[Julian Stecklina]

On Tue, 23 Aug 2005 14:15:05 +0200
"Goffioul Michael" <goffioul at imec.be> wrote:

> > I doubt this is a very useful facility for general use. :)
> 
> It would be nice then to think about how to implement it into ECL.
> The first things that come to my mind are (concept code):
> - let's take a simple example of
> 	(def-callback cb-plus ((a :int) (b :int)) :returning :int
> 	  (+ a b))
> - this should be converted into a pure LISP function like:
> 	(defun <some-name> (a b)
> 	  (+ a b))
>   which is compiled, possibly making use of (declare (si::c-local))
>   (indeed, in ECL, we cannot build C/LISP interaction without
> compilation)
> - a C wrapper should also be written, like
> 	int cb_plus(int a, int b) {
> 	  return object_to_integer(<some-name>(make_integer(a),
> make_integer(b))); }
> - a foreign pointer can be constructed to get a reference to the
> callback ecl_make_foreign_data(@:void, 0, cb_plus)
> 
> I have the impression that all the needed parts are already present
> in the compiler, but it requires some user-level interface and
> compiler hacking.

Compiler hacking should be minimal, I'll do a prototype.

Regards,
-- 
Julian Stecklina

(Of course SML does have its weaknesses, but by comparison, a
 discussion of C++'s strengths and flaws always sounds like an
 argument about whether one should face north or east when one
 is sacrificing one's goat to the rain god.)         -- Thant Tessman