--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lisp/hyperbole/hvar.el	Mon Aug 13 08:45:50 2007 +0200
@@ -0,0 +1,55 @@
+;;!emacs
+;;
+;; FILE:         hvar.el
+;; SUMMARY:      Variable manipulation routines for Hyperbole.
+;; USAGE:        GNU Emacs Lisp Library
+;; KEYWORDS:     extensions, hypermedia
+;;
+;; AUTHOR:       Bob Weiner
+;; ORG:          Brown U.
+;;
+;; ORIG-DATE:     1-Oct-91 at 14:00:24
+;; LAST-MOD:     14-Apr-95 at 16:13:46 by Bob Weiner
+;;
+;; This file is part of Hyperbole.
+;; Available for use and distribution under the same terms as GNU Emacs.
+;;
+;; Copyright (C) 1991-1995, Free Software Foundation, Inc.
+;; Developed with support from Motorola Inc.
+;;
+;; DESCRIPTION:  
+;; DESCRIP-END.
+
+;;; ************************************************************************
+;;; Other required Elisp libraries
+;;; ************************************************************************
+
+(require 'set)
+
+;;; ************************************************************************
+;;; Public functions
+;;; ************************************************************************
+
+;;;###autoload
+(defun var:append (var-symbol-name list-to-add)
+  "Appends to value held by VAR-SYMBOL-NAME, LIST-TO-ADD.  Returns new value.
+If VAR-SYMBOL-NAME is unbound, it is set to LIST-TO-ADD.
+Often used to append to 'hook' variables."
+  (let ((val))
+    (if (and (boundp var-symbol-name)
+	     (setq val (symbol-value var-symbol-name))
+	     (or (if (symbolp val) (setq val (cons val nil)))
+		 (listp val)))
+	;; Don't add if list elts are already there.
+	(if (memq nil (mapcar (function
+				(lambda (elt) (set:member elt val)))
+			      list-to-add))
+	    (set-variable var-symbol-name
+			  (if (eq (car val) 'lambda)
+			      (apply 'list val list-to-add)
+			    (append val list-to-add)))
+	  val)
+      (set-variable var-symbol-name list-to-add))))
+
+(provide 'hvar)
+