Hello Ying, On Sat, Apr 11, 2015 at 1:50 AM, Huang, Ying <huang_ying_cari...@163.com> wrote: > I need to manipulate foreign array. I tried to define an extended > foreign array type because there are some features that are lacking in > foreign-array-type of cffi. I can access/assign element of foreign array > with cffi:mem-ref and (setf cffi:mem-ref). But I don't know how to free > element of foreign array (the element type can be aggregated).
Indeed, in src/types.lisp:455 there's a FIXME mentioning just that! > I think if there is a cffi:mem-free (I know, the name is bad) like > cffi:mem-ref, may be this can be resolved. > > (defun mem-free (ptr type param &optional (offset 0)) > (let* ((parsed-type (parse-type type)) > (ctype (canonicalize parsed-type))) > (if (aggregatep parsed-type) > (free-translated-object (inc-pointer ptr offset) > parsed-type param) > (free-translated-object (%mem-ref ptr ctype offset) > parsed-type param)))) My first intuition would be to fix foreign-array-free to get a type argument. That way it would know how to free each element, essentially doing a mem-free (as you call it) for each element in the array. I've prototyped such a smarter foreign-array-free here: https://github.com/luismbo/cffi/commit/0a7d42720eacc32abb4338df32b4e5fceecdeb6d Your example then becomes: CFFI> (defparameter *string-array* (foreign-array-alloc #("a" "b" "c") '(:array :string 3))) *STRING-ARRAY* CFFI> (trace foreign-string-free) (FOREIGN-STRING-FREE) CFFI> (foreign-array-free *STRING-ARRAY* '(:array :string 3)) 0: (FOREIGN-STRING-FREE #.(SB-SYS:INT-SAP #X002054A0)) 0: FOREIGN-STRING-FREE returned NIL 0: (FOREIGN-STRING-FREE #.(SB-SYS:INT-SAP #X002054B0)) 0: FOREIGN-STRING-FREE returned NIL 0: (FOREIGN-STRING-FREE #.(SB-SYS:INT-SAP #X002054C0)) 0: FOREIGN-STRING-FREE returned NIL NIL Let me know what you think. :) Cheers, -- Luís Oliveira http://kerno.org/~luis/
