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;;; master.el --- make a buffer the master over another buffer
;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005 Alexander Schroeder
;; Author: Alex Schroeder <>
;; Maintainer: Alex Schroeder <>
;; Version: 1.0.2
;; Keywords: comm
;; 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
;; 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:
;; master-mode is a minor mode which enables you to scroll another
;; buffer (the slave) without leaving your current buffer (the master).
;; It can be used by sql.el, for example: The SQL buffer is the master
;; and its SQLi buffer is the slave. This allows you to scroll the SQLi
;; buffer containing the output from the SQL buffer containing the
;; commands.
;; This is how to use sql.el and master.el together: The variable
;; sql-buffer contains the slave buffer. It is a local variable in the
;; SQL buffer.
;; (add-hook 'sql-mode-hook
;; (function (lambda ()
;; (master-mode t)
;; (master-set-slave sql-buffer))))
;; (add-hook 'sql-set-sqli-hook
;; (function (lambda ()
;; (master-set-slave sql-buffer))))
;;; Thanks to all the people who helped me out:
;; Rob Riepel <>
;;; History:
;;; Code:
(defgroup master nil
"Support for master/slave relationships between buffers."
:version "22.1"
:group 'convenience)
;; Variables that don't need initialization.
(defvar master-of nil
"Slave buffer of the current buffer. See `master-mode'.
You can set this variable using `master-set-slave'.")
(defvar master-set-slave-hook nil
"Hook run after the slave is changed using \\[master-set-slave].")
;;; Define master mode.
(define-minor-mode master-mode
"Toggle Master mode.
With no argument, this command toggles the mode.
Non-null prefix argument turns on the mode.
Null prefix argument turns off the mode.
When Master mode is enabled, you can scroll the slave buffer using the
following commands:
The slave buffer is stored in the buffer-local variable `master-of'.
You can set this variable using `master-set-slave'. You can show
yourself the value of `master-of' by calling `master-show-slave'."
:group 'master
'(("\C-c\C-n" . master-says-scroll-up)
("\C-c\C-p" . master-says-scroll-down)
("\C-c<" . master-says-beginning-of-buffer)
("\C-c>" . master-says-end-of-buffer)
("\C-c\C-l" . master-says-recenter)))
;; Initialize Master mode by setting a slave buffer.
(defun master-set-slave (buffer)
"Makes BUFFER the slave of the current buffer.
Use \\[master-mode] to toggle control of the slave buffer."
(interactive "bSlave: ")
(make-local-variable 'master-of)
(setq master-of buffer)
(run-hooks 'master-set-slave-hook))
(defun master-show-slave ()
"Displays a message with the name of the slave buffer."
(message "This buffer is the master of %s. Master-mode is %S."
(or master-of "none")
;;; Functions that the master buffer can call for the slave buffer.
(defun master-says-scroll-up (&optional arg)
"Display and scroll the slave buffer up.
See `scroll-up'."
(master-says 'scroll-up arg))
(defun master-says-scroll-down (&optional arg)
"Display and scroll the slave buffer down.
See `scroll-down'."
(master-says 'scroll-down arg))
(defun master-says-beginning-of-buffer (&optional arg)
"Display and move to the beginning of the slave buffer.
See `beginning-of-buffer'."
(master-says 'beginning-of-buffer arg))
(defun master-says-end-of-buffer (&optional arg)
"Display and move to the end of the slave buffer.
See `end-of-buffer'."
(master-says 'end-of-buffer arg))
(defun master-says-recenter (&optional arg)
"Recenter the slave buffer.
See `recenter'."
(master-says 'recenter arg))
;; The master function doing the stuff.
(defun master-says (&optional command arg)
"Display slave buffer and execute COMMAND with ARG in its window."
(if (null (buffer-live-p (get-buffer master-of)))
(error "Slave buffer has disappeared")
(let ((window (selected-window)))
(if (not (eq (window-buffer window) (get-buffer master-of)))
(switch-to-buffer-other-window master-of))
(if command (condition-case nil (apply command arg) (error nil)))
(select-window window))))
(provide 'master)
;;; arch-tag: dca08daa-8127-45ae-b77e-b135160dce98
;;; master.el ends here
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