>>>>> 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
