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;;; hvar.el --- Variable manipulation routines for Hyperbole.
;; Copyright (C) 1991-1995, Free Software Foundation, Inc.
;; Developed with support from Motorola Inc.
;; Author: Bob Weiner, Brown U.
;; Maintainer: Mats Lidell <matsl@contactor.se>
;; Keywords: extensions, hypermedia
;; This file is part of GNU Hyperbole.
;; GNU Hyperbole is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or (at
;; your option) any later version.
;; GNU Hyperbole is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Commentary:
;;; Code:
;;;
;;; 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)
;;; hvar.el ends here
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