diff options
Diffstat (limited to 'lisp/emacs-lisp/gv.el')
| -rw-r--r-- | lisp/emacs-lisp/gv.el | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/lisp/emacs-lisp/gv.el b/lisp/emacs-lisp/gv.el index e3e5b321047..279ae582a05 100644 --- a/lisp/emacs-lisp/gv.el +++ b/lisp/emacs-lisp/gv.el @@ -217,13 +217,15 @@ instead the assignment is turned into something equivalent to temp) so as to preserve the semantics of `setf'." (declare (debug (sexp (&or symbolp lambda-expr) &optional sexp))) + (when (eq 'lambda (car-safe setter)) + (message "Use `gv-define-setter' or name %s's setter function" name)) `(gv-define-setter ,name (val &rest args) ,(if fix-return `(macroexp-let2 nil v val `(progn - (,',setter ,@(append args (list v))) + (,',setter ,@args ,v) ,v)) - `(cons ',setter (append args (list val)))))) + ``(,',setter ,@args ,val)))) ;;; Typical operations on generalized variables. @@ -441,6 +443,26 @@ 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))))) + +(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'." + (funcall (car ref))) +;; Don't use `declare' because it seems to introduce circularity problems: +;; Warning: Eager macro-expansion skipped due to cycle: +;; … => (load "gv.el") => (macroexpand-all (defsubst gv-deref …)) => (macroexpand (defun …)) => (load "gv.el") +(gv-define-setter gv-deref (v ref) `(funcall (cdr ,ref) ,v)) + ;;; Vaguely related definitions that should be moved elsewhere. ;; (defun alist-get (key alist) |