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168 lines
6.8 KiB
EmacsLisp
168 lines
6.8 KiB
EmacsLisp
;;; novice.el --- handling of disabled commands ("novice mode") for Emacs -*- lexical-binding: t -*-
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;; Copyright (C) 1985-1987, 1994, 2001-2024 Free Software Foundation,
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;; Inc.
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: internal, help
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This mode provides a hook which is, by default, attached to various
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;; putatively dangerous commands in a (probably futile) attempt to
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;; prevent lusers from shooting themselves in the feet.
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;;; Code:
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;; This function is called (by autoloading)
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;; to handle any disabled command.
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;; The command is found in this-command
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;; and the keys are returned by (this-command-keys).
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;;;###autoload
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(defvar disabled-command-function 'disabled-command-function
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"Function to call to handle disabled commands.
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If nil, the feature is disabled, i.e., all commands work normally.")
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;; It is ok here to assume that this-command is a symbol
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;; because we won't get called otherwise.
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;;;###autoload
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(defun disabled-command-function (&optional cmd keys)
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(let* ((cmd (or cmd this-command))
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(keys (or keys (this-command-keys)))
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(help-string
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(concat
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(if (or (eq (aref keys 0)
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(if (stringp keys)
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(aref "\M-x" 0)
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?\M-x))
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(and (>= (length keys) 2)
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(eq (aref keys 0) meta-prefix-char)
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(eq (aref keys 1) ?x)))
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(format "You have invoked the disabled command %s.\n" cmd)
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(substitute-command-keys
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(format "You have typed \\`%s', invoking disabled command %s.\n"
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(key-description keys) cmd)))
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;; Any special message saying why the command is disabled.
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(if (stringp (get cmd 'disabled))
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(get cmd 'disabled)
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(concat
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"It is disabled because new users often find it confusing.\n"
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(substitute-command-keys
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"Here's the first part of its description:\n\n")
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;; Keep only the first paragraph of the documentation.
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(with-temp-buffer
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(insert (or (condition-case ()
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(documentation cmd)
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(error nil))
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"<< not documented >>"))
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(goto-char (point-min))
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(when (search-forward "\n\n" nil t)
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(delete-region (match-beginning 0) (point-max)))
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(indent-rigidly (point-min) (point-max) 3)
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(buffer-string))))
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(substitute-command-keys "\n
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Do you want to use this command anyway?
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You can now type:
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\\`n' (also C-g) to cancel--don't try the command; it remains disabled.
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\\`y' to enable the command (no questions if you use it again).
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\\`SPC' to try the command just this once, but leave it disabled.
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\\`!' to enable it and all the disabled commands for this session.")))
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(char
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;; Note: the prompt produced from the choices below must not
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;; overflow a single screen line, because otherwise it will
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;; cause the mini-window to resize, which will in turn hide
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;; the last line of the help text above: the code which fits
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;; the window to the size of the help text does not expect
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;; the mini-window to become taller.
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(car (read-multiple-choice "Use this command?"
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'((?n "no")
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(?y "yes")
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(?\s "(space bar) only once")
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(?! "use and enable all"))
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help-string
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"*Disabled Command*"))))
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(pcase char
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(?\C-g (setq quit-flag t))
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(?! (setq disabled-command-function nil))
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(?y
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(if (and user-init-file
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(not (string= "" user-init-file))
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(y-or-n-p "Enable command for future editing sessions also? "))
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(enable-command cmd)
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(put cmd 'disabled nil))))
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(unless (char-equal char ?n)
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(call-interactively cmd))))
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(defun en/disable-command (command disable)
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(unless (commandp command)
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(error "Invalid command name `%s'" command))
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(put command 'disabled disable)
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(let ((init-file user-init-file)
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(default-init-file
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(if (eq system-type 'ms-dos) "~/_emacs" "~/.emacs")))
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(unless init-file
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(if (or (file-exists-p default-init-file)
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(and (eq system-type 'windows-nt)
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(file-exists-p "~/_emacs")))
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;; Started with -q, i.e. the file containing
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;; enabled/disabled commands hasn't been read. Saving
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;; settings there would overwrite other settings.
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(error "Saving settings from \"emacs -q\" would overwrite existing customizations"))
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(setq init-file default-init-file)
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(if (and (not (file-exists-p init-file))
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(eq system-type 'windows-nt)
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(file-exists-p "~/_emacs"))
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(setq init-file "~/_emacs")))
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(with-current-buffer (find-file-noselect
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(substitute-in-file-name init-file))
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(goto-char (point-min))
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(if (search-forward (concat "(put '" (symbol-name command) " ") nil t)
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(delete-region
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(progn (beginning-of-line) (point))
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(progn (forward-line 1) (point))))
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;; Explicitly enable, in case this command is disabled by default
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;; or in case the code we deleted was actually a comment.
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(goto-char (point-max))
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(unless (bolp) (newline))
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(insert "(put '" (symbol-name command) " 'disabled "
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(symbol-name disable) ")\n")
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(save-buffer))))
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;;;###autoload
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(defun enable-command (command)
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"Allow COMMAND to be executed without special confirmation from now on.
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COMMAND must be a symbol.
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This command alters the user's .emacs file so that this will apply
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to future sessions."
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(interactive "CEnable command: ")
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(en/disable-command command nil))
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;;;###autoload
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(defun disable-command (command)
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"Require special confirmation to execute COMMAND from now on.
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COMMAND must be a symbol.
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This command alters your init file so that this choice applies to
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future sessions."
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(interactive "CDisable command: ")
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(en/disable-command command t))
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(provide 'novice)
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;;; novice.el ends here
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