[Ecls-list] Accessing Lisp Structures in C code

[Juan Jose Garcia-Ripoll]

On Nov 24, 2007 6:12 PM, Jeremy Shoemaker <jeremy at codingkoi.com> wrote:
> How would I do it the other way?  Are you suggesting doing something like
> writing a lisp expression in a C string and then using c_string_to_object?

Forget it. You now have too simple functions

extern cl_object ecl_slot_value(cl_object x, const char *slot);
extern cl_object ecl_slot_value_set(cl_object x, const char *slot, cl_object y);

They take structures or CLOS objects, a slot name in the form of a
string with an optional package prefix and a possible new value for
the slot. They are far from optimal and safe, but better than nothing.

They also seem to work, as shown here:

$ cat foo.lsp
(defun foo (x)
  (ffi::c-inline (x) (t) t
   "ecl_slot_value(#0,\"b\")" :one-liner t))

(defun faa (x y)
 (ffi::c-inline (x y) (t t) t
  "ecl_slot_value_set(#0,\"b\",#1)" :one-liner t))

(defstruct a b)
(defvar *a* (make-a :b 1))
(print *a*)
(print (foo *a*))
(faa *a* 2)
(print (foo *a*))
(quit)
$ ecl -q -compile foo.lsp
;;; Loading #P"/Users/jjgarcia/lib/ecl/cmp.fas"
;;; Loading #P"/Users/jjgarcia/lib/ecl/sysfun.lsp"
$ ecl -eval '(load "foo")'
;;; Loading #P"/Users/jjgarcia/src/common-lisp.net/ecl/build/foo.fas"

#S(A :B 1)
1
2

-- 
Facultad de Fisicas, Universidad Complutense,
Ciudad Universitaria s/n Madrid 28040 (Spain)
http://juanjose.garciaripoll.googlepages.com