[cffi-devel] Mutable Pointers

[Luís Oliveira]

On 2006-jul-14, at 02:38, Stuart Sierra wrote:
> But POINTER-ADDRESS is not setf-able, is it?

Right. AFAICT, some of the Lisps supported by CFFI don't have mutable  
pointers.


> I want to do this:
>   (defcvar "stack_pointer" :pointer)
>
>   (incf (pointer-address *stack-pointer*))

See inc-pointer.
<http://common-lisp.net/project/cffi/manual/html_node/ 
inc_002dpointer.html>

(setf *stack-pointer* (inc-pointer *stack-pointer* 1)) should work.  
You can abstract that with a simple macro:

   (defmacro incf-pointer (place &optional (offset 1))
     `(setf ,place (inc-pointer ,place ,offset)))

Any objections to adding this macro to CFFI?

-- 
Luís Oliveira
http://student.dei.uc.pt/~lmoliv/