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;;; novice.el --- handling of disabled commands ("novice mode") for Emacs
;; Copyright (C) 1985, 1986, 1987, 1994, 2002, 2003, 2004,
;; 2005, 2006 Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: internal, help
;; This file is part of GNU Emacs.
;; GNU Emacs 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 Emacs 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:
;; This mode provides a hook which is, by default, attached to various
;; putatively dangerous commands in a (probably futile) attempt to
;; prevent lusers from shooting themselves in the feet.
;;; Code:
;; This function is called (by autoloading)
;; to handle any disabled command.
;; The command is found in this-command
;; and the keys are returned by (this-command-keys).
;;;###autoload
(defvar disabled-command-function 'disabled-command-function
"Function to call to handle disabled commands.
If nil, the feature is disabled, i.e., all commands work normally.")
;;;###autoload
(define-obsolete-variable-alias 'disabled-command-hook 'disabled-command-function "22.1")
;; It is ok here to assume that this-command is a symbol
;; because we won't get called otherwise.
;;;###autoload
(defun disabled-command-function (&rest ignore)
(let (char)
(save-window-excursion
(with-output-to-temp-buffer "*Disabled Command*"
(let ((keys (this-command-keys)))
(if (or (eq (aref keys 0)
(if (stringp keys)
(aref "\M-x" 0)
?\M-x))
(and (>= (length keys) 2)
(eq (aref keys 0) meta-prefix-char)
(eq (aref keys 1) ?x)))
(princ (format "You have invoked the disabled command %s.\n"
(symbol-name this-command)))
(princ (format "You have typed %s, invoking disabled command %s.\n"
(key-description keys) (symbol-name this-command)))))
;; Print any special message saying why the command is disabled.
(if (stringp (get this-command 'disabled))
(princ (get this-command 'disabled))
(princ "It is disabled because new users often find it confusing.\n")
(princ "Here's the first part of its description:\n\n")
;; Keep only the first paragraph of the documentation.
(with-current-buffer "*Disabled Command*"
(goto-char (point-max))
(let ((start (point)))
(save-excursion
(princ (or (condition-case ()
(documentation this-command)
(error nil))
"<< not documented >>")))
(if (search-forward "\n\n" nil t)
(delete-region (match-beginning 0) (point-max)))
(goto-char (point-max))
(indent-rigidly start (point) 3))))
(princ "\n\nDo you want to use this command anyway?\n\n")
(princ "You can now type
y to try it and enable it (no questions if you use it again).
n to cancel--don't try the command, and it remains disabled.
SPC to try the command just this once, but leave it disabled.
! to try it, and enable all disabled commands for this session only.")
(save-excursion
(set-buffer standard-output)
(help-mode)))
(message "Type y, n, ! or SPC (the space bar): ")
(let ((cursor-in-echo-area t))
(while (progn (setq char (read-event))
(or (not (numberp char))
(not (memq (downcase char)
'(?! ?y ?n ?\ ?\C-g)))))
(ding)
(message "Please type y, n, ! or SPC (the space bar): "))))
(setq char (downcase char))
(if (= char ?\C-g)
(setq quit-flag t))
(if (= char ?!)
(setq disabled-command-function nil))
(if (= char ?y)
(if (and user-init-file
(not (string= "" user-init-file))
(y-or-n-p "Enable command for future editing sessions also? "))
(enable-command this-command)
(put this-command 'disabled nil)))
(if (/= char ?n)
(call-interactively this-command))))
;;;###autoload
(defun enable-command (command)
"Allow COMMAND to be executed without special confirmation from now on.
COMMAND must be a symbol.
This command alters the user's .emacs file so that this will apply
to future sessions."
(interactive "CEnable command: ")
(put command 'disabled nil)
(let ((init-file user-init-file)
(default-init-file
(if (eq system-type 'ms-dos) "~/_emacs" "~/.emacs")))
(when (null init-file)
(if (or (file-exists-p default-init-file)
(and (eq system-type 'windows-nt)
(file-exists-p "~/_emacs")))
;; Started with -q, i.e. the file containing
;; enabled/disabled commands hasn't been read. Saving
;; settings there would overwrite other settings.
(error "Saving settings from \"emacs -q\" would overwrite existing customizations"))
(setq init-file default-init-file)
(if (and (not (file-exists-p init-file))
(eq system-type 'windows-nt)
(file-exists-p "~/_emacs"))
(setq init-file "~/_emacs")))
(save-excursion
(set-buffer (find-file-noselect
(substitute-in-file-name init-file)))
(goto-char (point-min))
(if (search-forward (concat "(put '" (symbol-name command) " ") nil t)
(delete-region
(progn (beginning-of-line) (point))
(progn (forward-line 1) (point))))
;; Explicitly enable, in case this command is disabled by default
;; or in case the code we deleted was actually a comment.
(goto-char (point-max))
(insert "\n(put '" (symbol-name command) " 'disabled nil)\n")
(save-buffer))))
;;;###autoload
(defun disable-command (command)
"Require special confirmation to execute COMMAND from now on.
COMMAND must be a symbol.
This command alters the user's .emacs file so that this will apply
to future sessions."
(interactive "CDisable command: ")
(if (not (commandp command))
(error "Invalid command name `%s'" command))
(put command 'disabled t)
(let ((init-file user-init-file)
(default-init-file
(if (eq system-type 'ms-dos) "~/_emacs" "~/.emacs")))
(when (null init-file)
(if (or (file-exists-p default-init-file)
(and (eq system-type 'windows-nt)
(file-exists-p "~/_emacs")))
;; Started with -q, i.e. the file containing
;; enabled/disabled commands hasn't been read. Saving
;; settings there would overwrite other settings.
(error "Saving settings from \"emacs -q\" would overwrite existing customizations"))
(setq init-file default-init-file)
(if (and (not (file-exists-p init-file))
(eq system-type 'windows-nt)
(file-exists-p "~/_emacs"))
(setq init-file "~/_emacs")))
(save-excursion
(set-buffer (find-file-noselect
(substitute-in-file-name init-file)))
(goto-char (point-min))
(if (search-forward (concat "(put '" (symbol-name command) " ") nil t)
(delete-region
(progn (beginning-of-line) (point))
(progn (forward-line 1) (point)))
(goto-char (point-max))
(insert ?\n))
(insert "(put '" (symbol-name command) " 'disabled t)\n")
(save-buffer))))
(provide 'novice)
;; arch-tag: f83c0f96-497e-4db6-a430-8703716c6dd9
;;; novice.el ends here
|
