Thanks alot Martin ...that worked like a charm! =)
On Friday, October 25, 2013 4:20 AM, Martin Simmons martin@lispworks.com wrote:
On Thu, 24 Oct 2013 17:30:49 -0700 (PDT), Joeish W said:
here is the defcfun and deffun combo
;; void cvSplit(const CvArr* src, CvArr* dst0, CvArr* dst1, CvArr* dst2, CvArr* dst3) ;; Note: I had to use "CV-MERGE" instead of "MERGE" for the Common Lisp name of CV-MERGE so I named this ;; function CV-SPLIT so they would match. (cffi:defcfun ("cvSplit" %split) :void (src cv-arr) (dest-0 cv-arr) (dest-1 cv-arr) (dest-2 cv-arr) (dest-3 cv-arr)) (defun cv-split (src dest-0 &optional (dest-1 (cffi:null-pointer)) (dest-2 (cffi:null-pointer)) (dest-3 (cffi:null-pointer))) "Divides a multi-channel array into several single-channel arrays." (%split src dest-0 dest-1 dest-2 dest-3))
it works as expected ...no errors at all
my attempt at a macro(new to macros) below works in one piece of code when the defun it is in is evaluated at the repl then ran at the repl
;; #define cvCvtPixToPlane cvSplit (defmacro cvt-pix-to-plane (src dest-0 &optional (dest-1 (cffi:null-pointer)) (dest-2 (cffi:null-pointer)) (dest-3 (cffi:null-pointer))) "Macro for CV-SPLIT" `(cv-split ,src ,dest-0 ,dest-1 ,dest-2 ,dest-3))
but in the same code when used the exact same way inside emacs (using slime/sbcl on ubuntu saucy) when it is placed inside a newly opened file (.lisp) or even my well used test.lisp file and ran with slime-compile-and-load-file i get
error: Objects of type SB-SYS:SYSTEM-AREA-POINTER can't be dumped into fasl files. --> CL-OPENCV::CV-SPLIT ==> #.(SB-SYS:INT-SAP #X00000000)
can you help me figure out the issue and write macros with null-pointers correctly
This is a common gotcha with &optional/&key in macros: the default value is evaluated during macroexpansion, so in general it should be a form.
I.e. you need `(cffi:null-pointer) instead of (cffi:null-pointer).
__Martin