Re: [cffi-devel] Mutable Pointers

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?