Luís Oliveira wrote:
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 suspected as much. I couldn't find it in SBCL's FFI, at least.
(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)))
But won't that set the value that *STACK-POINTER* points to? In my
example, *STACK-POINTER* is not a Lisp object but a foreign global
variable accessed by name with DEFCVAR. As I understand CFFI's :POINTER
type, the above macro will modify the memory location that PLACE points
to but will not modify PLACE itself.
-Stuart
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