* lisp/emacs-lisp/gv.el (gv-ref, gv-deref): New function and macro.

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 7c51b139ec3334a910db275c23552a84459ab0ec..e0ff05aa7dc6f7e2f02c18b2f91ac115f459241e 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2012-11-08  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+       * emacs-lisp/gv.el (gv-ref, gv-deref): New function and macro.
+
 2012-11-07  Michael Albinus  <michael.albinus@gmx.de>
 
        * notifications.el (notifications-get-server-information-method):

diff --git a/lisp/emacs-lisp/gv.el b/lisp/emacs-lisp/gv.el
index d6c91539a90423aefc9dbbe25564743df22233d4..34e29ba1cbdfb5be50012013ec73530f2e2b5e36 100644 (file)
--- a/lisp/emacs-lisp/gv.el
+++ b/lisp/emacs-lisp/gv.el
@@ -433,6 +433,24 @@ The return value is the last VAL in the list.
                        `(logior (logand ,v ,mask)
                                 (logand ,getter (lognot ,mask))))))))))
 
+;;; References
+
+;;;###autoload
+(defmacro gv-ref (place)
+  "Return a reference to PLACE.
+This is like the `&' operator of the C language."
+  (gv-letplace (getter setter) place
+    `(cons (lambda () ,getter)
+           (lambda (gv--val) ,(funcall setter 'gv--val)))))
+
+;;;###autoload
+(defsubst gv-deref (ref)
+  "Dereference REF, returning the referenced value.
+This is like the `*' operator of the C language.
+REF must have been previously obtained with `gv-ref'."
+  (declare (gv-setter (lambda (v) `(funcall (cdr ,ref) ,v))))
+  (funcall (car ref)))
+
 ;;; Vaguely related definitions that should be moved elsewhere.
 
 ;; (defun alist-get (key alist)