;;; novice.el --- handling of disabled commands ("novice mode") for Emacs -*- lexical-binding: t -*-
;; Copyright (C) 1985-1987, 1994, 2001-2024 Free Software Foundation,
;; Inc.
;; Maintainer: emacs-devel@gnu.org
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; 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.")
;; It is ok here to assume that this-command is a symbol
;; because we won't get called otherwise.
;;;###autoload
(defun disabled-command-function (&optional cmd keys)
(let* ((cmd (or cmd this-command))
(keys (or keys (this-command-keys)))
(help-string
(concat
(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)))
(format "You have invoked the disabled command %s.\n" cmd)
(substitute-command-keys
(format "You have typed \\`%s', invoking disabled command %s.\n"
(key-description keys) cmd)))
;; Any special message saying why the command is disabled.
(if (stringp (get cmd 'disabled))
(get cmd 'disabled)
(concat
"It is disabled because new users often find it confusing.\n"
(substitute-command-keys
"Here's the first part of its description:\n\n")
;; Keep only the first paragraph of the documentation.
(with-temp-buffer
(insert (or (condition-case ()
(documentation cmd)
(error nil))
"<< not documented >>"))
(goto-char (point-min))
(when (search-forward "\n\n" nil t)
(delete-region (match-beginning 0) (point-max)))
(indent-rigidly (point-min) (point-max) 3)
(buffer-string))))
(substitute-command-keys "\n
Do you want to use this command anyway?
You can now type:
\\`n' (also C-g) to cancel--don't try the command; it remains disabled.
\\`y' to enable the command (no questions if you use it again).
\\`SPC' to try the command just this once, but leave it disabled.
\\`!' to enable it and all the disabled commands for this session.")))
(char
;; Note: the prompt produced from the choices below must not
;; overflow a single screen line, because otherwise it will
;; cause the mini-window to resize, which will in turn hide
;; the last line of the help text above: the code which fits
;; the window to the size of the help text does not expect
;; the mini-window to become taller.
(car (read-multiple-choice "Use this command?"
'((?n "no")
(?y "yes")
(?\s "(space bar) only once")
(?! "use and enable all"))
help-string
"*Disabled Command*"))))
(pcase char
(?\C-g (setq quit-flag t))
(?! (setq disabled-command-function nil))
(?y
(if (and user-init-file
(not (string= "" user-init-file))
(y-or-n-p "Enable command for future editing sessions also? "))
(enable-command cmd)
(put cmd 'disabled nil))))
(unless (char-equal char ?n)
(call-interactively cmd))))
(defun en/disable-command (command disable)
(unless (commandp command)
(error "Invalid command name `%s'" command))
(put command 'disabled disable)
(let ((init-file user-init-file)
(default-init-file
(if (eq system-type 'ms-dos) "~/_emacs" "~/.emacs")))
(unless 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")))
(with-current-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))
(unless (bolp) (newline))
(insert "(put '" (symbol-name command) " 'disabled "
(symbol-name disable) ")\n")
(save-buffer))))
;;;###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: ")
(en/disable-command command nil))
;;;###autoload
(defun disable-command (command)
"Require special confirmation to execute COMMAND from now on.
COMMAND must be a symbol.
This command alters your init file so that this choice applies to
future sessions."
(interactive "CDisable command: ")
(en/disable-command command t))
(provide 'novice)
;;; novice.el ends here