;;; novice.el --- handling of disabled commands ("novice mode") for Emacs -*- lexical-binding: t -*- ;; Copyright (C) 1985-1987, 1994, 2001-2023 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 . ;;; 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 (condition-case () (documentation cmd) (error "<< 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