Stefan Monnier <[EMAIL PROTECTED]> writes: >> A general solution is non-trivial, as there is a potential risk of memory >> leaks, as associating ordering information with arbitrary lisp objects >> means that we must store a pointer to such objects somewhere, and thus >> may leave references to otherwise unused data. > > How 'bout the patch below? Look 'ma, no leak!
Very clever -- I have to tune into weak hash tables more often :-) I'm all for it. Remember to update doc string and lispref too. > > > Stefan > > > --- subr.el 14 jun 2005 13:16:55 -0400 1.464 > +++ subr.el 14 jun 2005 13:23:20 -0400 > @@ -974,25 +974,21 @@ > `list-order' property. > > The return value is the new value of LIST-VAR." > - (let* ((ordering (get list-var 'list-order)) > - (cur (and (symbolp element) (assq element ordering)))) > + (let ((ordering (get list-var 'list-order))) > + (unless ordering > + (put list-var 'list-order > + (setq ordering (make-hash-table :weakness 'key :test 'eq)))) > (when order > - (unless (symbolp element) > - (error "cannot specify order for non-symbols")) > - (if cur > - (setcdr cur order) > - (setq cur (cons element order)) > - (setq ordering (cons cur ordering)) > - (put list-var 'list-order ordering))) > + (puthash element order ordering)) > (add-to-list list-var element) > (set list-var (sort (symbol-value list-var) > (lambda (a b) > - (let ((oa (and (symbolp a) (assq a ordering))) > - (ob (and (symbolp b) (assq b ordering)))) > + (let ((oa (gethash a ordering)) > + (ob (gethash b ordering))) > (cond > ((not oa) nil) > ((not ob) t) > - (t (< (cdr oa) (cdr ob)))))))))) > + (t (< oa ob))))))))) > > > ;;; Load history > > -- Kim F. Storm <[EMAIL PROTECTED]> http://www.cua.dk _______________________________________________ Emacs-devel mailing list Emacs-devel@gnu.org http://lists.gnu.org/mailman/listinfo/emacs-devel
