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|
;;; symbols.el --- functions for working with symbols and symbol values
;; Copyright (C) 1996 Ben Wing.
;; Maintainer: XEmacs Development Team
;; Keywords: internal
;; This file is part of XEmacs.
;; XEmacs 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.
;; XEmacs 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 XEmacs; see the file COPYING. If not, write to the
;; Free Software Foundation, 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Synched up with: Not in FSF.
;;; Commentary:
;; Not yet dumped into XEmacs.
;; The idea behind magic variables is that you can specify arbitrary
;; behavior to happen when setting or retrieving a variable's value. The
;; purpose of this is to make it possible to cleanly provide support for
;; obsolete variables (e.g. unread-command-event, which is obsolete for
;; unread-command-events) and variable compatibility
;; (e.g. suggest-key-bindings, the FSF equivalent of
;; teach-extended-commands-p and teach-extended-commands-timeout).
;; There are a large number of functions pertaining to a variable's
;; value:
;; boundp
;; globally-boundp
;; makunbound
;; symbol-value
;; set / setq
;; default-boundp
;; default-value
;; set-default / setq-default
;; make-variable-buffer-local
;; make-local-variable
;; kill-local-variable
;; kill-console-local-variable
;; symbol-value-in-buffer
;; symbol-value-in-console
;; local-variable-p / local-variable-if-set-p
;; Plus some "meta-functions":
;; defvaralias
;; variable-alias
;; indirect-variable
;; I wanted an implementation that:
;; -- would work with all the above functions, but (a) didn't require
;; a separate handler for every function, and (b) would work OK
;; even if more functions are added (e.g. `set-symbol-value-in-buffer'
;; or `makunbound-default') or if more arguments are added to a
;; function.
;; -- avoided consing if at all possible.
;; -- didn't slow down operations on non-magic variables (therefore,
;; storing the magic information using `put' is ruled out).
;;
;;; Code:
;; perhaps this should check whether the functions are bound, so that
;; some handlers can be unspecified. That requires that all functions
;; are defined before `define-magic-variable-handlers' is called,
;; though.
;; perhaps there should be something that combines
;; `define-magic-variable-handlers' with `defvaralias'.
(defun define-magic-variable-handlers (variable handler-class harg)
"Set the magic variable handles for VARIABLE to those in HANDLER-CLASS.
HANDLER-CLASS should be a symbol. The handlers are constructed by adding
the handler type to HANDLER-CLASS. HARG is passed as the HARG value for
each of the handlers."
(mapcar
#'(lambda (htype)
(set-magic-variable-handler variable htype
(intern (concat (symbol-value handler-class)
"-"
(symbol-value htype)))
harg))
'(get-value set-value other-predicate other-action)))
;; unread-command-event
(defun mvh-first-of-list-get-value (sym fun args harg)
(car (apply fun harg args)))
(defun mvh-first-of-list-set-value (sym value setfun getfun args harg)
(apply setfun harg (cons value (apply getfun harg args)) args))
(defun mvh-first-of-list-other-predicate (sym fun args harg)
(apply fun harg args))
(defun mvh-first-of-list-other-action (sym fun args harg)
(apply fun harg args))
(define-magic-variable-handlers 'unread-command-event
'mvh-first-of-list
'unread-command-events)
;; last-command-char, last-input-char, unread-command-char
(defun mvh-char-to-event-get-value (sym fun args harg)
(event-to-character (apply fun harg args)))
(defun mvh-char-to-event-set-value (sym value setfun getfun args harg)
(let ((event (apply getfun harg args)))
(if (event-live-p event)
nil
(setq event (make-event))
(apply setfun harg event args))
(character-to-event value event)))
(defun mvh-char-to-event-other-predicate (sym fun args harg)
(apply fun harg args))
(defun mvh-char-to-event-other-action (sym fun args harg)
(apply fun harg args))
(define-magic-variable-handlers 'last-command-char
'mvh-char-to-event
'last-command-event)
(define-magic-variable-handlers 'last-input-char
'mvh-char-to-event
'last-input-event)
(define-magic-variable-handlers 'unread-command-char
'mvh-char-to-event
'unread-command-event)
;; suggest-key-bindings
(set-magic-variable-handler
'suggest-key-bindings 'get-value
#'(lambda (sym fun args harg)
(and (apply fun 'teach-extended-commands-p args)
(apply fun 'teach-extended-commands-timeout args))))
(set-magic-variable-handler
'suggest-key-bindings 'set-value
#'(lambda (sym value setfun getfun args harg)
(apply setfun 'teach-extended-commands-p (not (null value)) args)
(if value
(apply 'teach-extended-commands-timeout
(if (numberp value) value 2) args))))
(set-magic-variable-handler
'suggest-key-bindings 'other-action
#'(lambda (sym fun args harg)
(apply fun 'teach-extended-commands-p args)
(apply fun 'teach-extended-commands-timeout args)))
(set-magic-variable-handler
'suggest-key-bindings 'other-predicate
#'(lambda (sym fun args harg)
(and (apply fun 'teach-extended-commands-p args)
(apply fun 'teach-extended-commands-timeout args))))
;;; symbols.el ends here
|
