Excerpt of message (sent 11 January 1993) by Richard Mlynarik:
> One should immediately discount any elisp code which includes "(require 'cl)"

Oh dear, yet another of Richard's famously unhelpful flames...

Excerpt of message (sent 11 January 93) by Nicolas Rouquette:
> If I may suggest against requiring the cl library, that'd be better.
> I have had some problems with it when using ilisp
>  and Jaime told me that it is not a great idea to load it.

Now that is a good example of tact and diplomacy, which, surprise, surprise,
is much more likely to win friends and influence people...

So here is buff-menu.el again minus the (require 'cl) and not using the
'unless' form.

--
Regards, David

8< ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ CUT HERE for file: buff-menu.el
;; Buffer menu main function and support functions.
;; Copyright (C) 1985, 1986, 1987, 1992 Free Software Foundation, Inc.

;; 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, 675 Mass Ave, Cambridge, MA 02139, USA.

; Put buffer *Buffer List* into proper mode right away
; so that from now on even list-buffers is enough to get a buffer menu.

(defvar Buffer-menu-mode-map nil "")

(if Buffer-menu-mode-map
    ()
  (setq Buffer-menu-mode-map (make-keymap))
  (suppress-keymap Buffer-menu-mode-map t)
  (define-key Buffer-menu-mode-map "q" 'Buffer-menu-select)
  (define-key Buffer-menu-mode-map "2" 'Buffer-menu-2-window)
  (define-key Buffer-menu-mode-map "1" 'Buffer-menu-1-window)
  (define-key Buffer-menu-mode-map "f" 'Buffer-menu-this-window)
  (define-key Buffer-menu-mode-map "o" 'Buffer-menu-other-window)
  (define-key Buffer-menu-mode-map "s" 'Buffer-menu-save)
  (define-key Buffer-menu-mode-map "d" 'Buffer-menu-delete)
  (define-key Buffer-menu-mode-map "k" 'Buffer-menu-delete)
  (define-key Buffer-menu-mode-map "\C-d" 'Buffer-menu-delete-backwards)
  (define-key Buffer-menu-mode-map "\C-k" 'Buffer-menu-delete)
  (define-key Buffer-menu-mode-map "x" 'Buffer-menu-execute)
  (define-key Buffer-menu-mode-map " " 'next-line)
  (define-key Buffer-menu-mode-map "\177" 'Buffer-menu-backup-unmark)
  (define-key Buffer-menu-mode-map "~" 'Buffer-menu-not-modified)
  (define-key Buffer-menu-mode-map "?" 'describe-mode)
  (define-key Buffer-menu-mode-map "u" 'Buffer-menu-unmark)
  (define-key Buffer-menu-mode-map "m" 'Buffer-menu-mark)
  (define-key Buffer-menu-mode-map "t" 'Buffer-menu-visit-tags-table)
  (define-key Buffer-menu-mode-map 'button2 'Buffer-menu-mouse-select)
  (define-key Buffer-menu-mode-map 'button3 'Buffer-menu-popup-menu)
  )

;; Buffer Menu mode is suitable only for specially formatted data.
(put 'Buffer-menu-mode 'mode-class 'special)

(defun Buffer-menu-mode ()
  "Major mode for editing a list of buffers.
Each line describes one of the buffers in Emacs.
Letters do not insert themselves; instead, they are commands.
m -- mark buffer to be displayed.
q -- select buffer of line point is on.
  Also show buffers marked with m in other windows.
1 -- select that buffer in full-screen window.
2 -- select that buffer in one window,
  together with buffer selected before this one in another window.
f -- select that buffer in place of the buffer menu buffer.
o -- select that buffer in another window,
  so the buffer menu buffer remains visible in its window.
t -- visit-tags-table this buffer.
~ -- clear modified-flag on that buffer.
s -- mark that buffer to be saved, and move down.
d or k -- mark that buffer to be deleted, and move down.
C-d -- mark that buffer to be deleted, and move up.
x -- delete or save marked buffers.
u -- remove all kinds of marks from current line.
Delete -- back up a line and remove marks.

Precisely,\\{Buffer-menu-mode-map}"
  (kill-all-local-variables)
  (use-local-map Buffer-menu-mode-map)
  (setq truncate-lines t)
  (setq buffer-read-only t)
  (setq major-mode 'Buffer-menu-mode)
  (setq mode-name "Buffer Menu")
  (require 'mode-motion)
  (setq mode-motion-hook 'mode-motion-highlight-line)
  (run-hooks 'buffer-menu-mode-hook))

(defvar Buffer-menu-buffer-column 4)

;; from mly@ai.mit.edu (Richard Mlynarik)
(defun Buffer-menu-buffer (error-if-non-existent-p)
  "Return buffer described by this line of buffer menu."
  (save-excursion
    (beginning-of-line)
    (forward-char Buffer-menu-buffer-column)
    (let* ((start (point))
           (string (if (/= (preceding-char) ?\")
                       ;; End of buffer name marked by tab or a space.
                       (progn (re-search-forward "\t\\| ")
                              (skip-chars-backward " \t")
                              (buffer-substring start (point)))
                       (progn
                         (backward-char 1)
                         (read (current-buffer))))))
      (or (get-buffer string)
	  (if error-if-non-existent-p
	      (error "No buffer named \"%s\"" string)
	    nil)))))

(defvar list-buffers-buffer-width 19
  "*Default width allowed for displaying buffer name in buffer menu")

(defun list-buffers-header-line ()
  (let ((blank (substring "                                                              "
                          0 (- list-buffers-buffer-width 7))))
    (concat " MR Buffer" blank "Size  Mode         File\n"
            " -- ------" blank "----  ----         ----\n")))

(defvar list-buffers-identification 'default-list-buffers-identification
  "String used to identify this buffer, or a function of one argument
to generate such a string.  This variable is always buffer-local.")
(make-variable-buffer-local 'list-buffers-identification)

(defun goto-column (column)
  "Move to column COLUMN in current line.
Differs from move-to-column in that it creates or modifies whitespace
if necessary to attain exactly the specified column."
  (interactive "NGoto column: ")
  (move-to-column column)
  (let ((col (current-column)))
    (if (< col column)
        (indent-to column)
      (if (and (/= col column)
               (= (preceding-char) ?\t))
          (let (indent-tabs-mode)
            (delete-char -1)
            (indent-to col)
            (move-to-column column))))))

(defun default-list-buffers-identification (output)
  (save-excursion
    (let ((file (or (buffer-file-name (current-buffer))
                    (and (boundp 'list-buffers-directory)
                         list-buffers-directory)))
          (size (buffer-size))
          (mode mode-name)
          p s)
      (set-buffer output)
      (prin1 size)
      (setq p (point))
      ;; right-justify the size
      (goto-column (1+ list-buffers-buffer-width))
      (setq s (- 6 (- p (point))))
      (while (> s 0) ; speed/consing tradeoff...
        (insert ? )
        (setq s (1- s)))
      (end-of-line)
      (indent-to (+ 9 list-buffers-buffer-width) 1)
      (insert mode)
      (if (not file)
          nil
        ;; if the mode-name is really long, clip it for the filename
        (if (> 0 (setq s (- (+ 21 list-buffers-buffer-width) (current-column))))
            (delete-char s))
        (indent-to (+ 22 list-buffers-buffer-width) 1)
        (insert file)))))

(defun list-buffers (&optional files-only no-check)
  "Display a list of names of existing buffers.
Inserts it in buffer *Buffer List* and displays that.
Note that buffers with names starting with spaces are omitted.
Non-null optional arg FILES-ONLY means mention only file buffers.
If NO-CHECK is non-nil, then list-buffers does not reset itself
if the maximum buffername length is found to be greater than
the variable list-buffers-buffer-width.

The M column contains a * for buffers that are modified.
The R column contains a % for buffers that are read-only."
  (interactive "P")
  (let* (tmpbuf
         (tmpbuflist (if (not no-check) (buffer-list)))
         (elt (if (not no-check) (length tmpbuflist))))
    (if (not no-check)
      (while (> elt 0)
        (setq elt (1- elt)
              tmpbuf (nth elt tmpbuflist))
        (setnth elt tmpbuflist
                (if (or (buffer-file-name tmpbuf) (null files-only))
                    (length (buffer-name tmpbuf))
                  0))))
    (let* ((current (current-buffer))
           (list-buffers-buffer-width (if no-check
                                          list-buffers-buffer-width
                                        (max list-buffers-buffer-width (+ 3 (apply 'max tmpbuflist)))))
           (col1 (1+ list-buffers-buffer-width))
           output)
      (save-excursion
        (with-output-to-temp-buffer "*Buffer List*"
          (let ((buffers (buffer-list)))
            (setq output standard-output)
            (set-buffer output)
            (Buffer-menu-mode)
            (setq buffer-read-only nil)
            (buffer-flush-undo output)
            (insert (list-buffers-header-line))
            (while buffers
              (let* ((buffer (car buffers))
                     (name (buffer-name buffer))
                     (file (buffer-file-name buffer)))
                (setq buffers (cdr buffers))
                (cond ((null name)) ;deleted buffer
                      ((and (/= 0 (length name));don't mention if starts with " "
                            (= (aref name 0) ?\ )))
                      ((and files-only (null file)))
                      (t
                       (set-buffer buffer)
                       (let ((ro buffer-read-only)
                             (id list-buffers-identification))
                         (set-buffer output)
                         (insert (if (eq buffer current)
                                     (progn (setq current (point)) ?\.)
                                   ?\ ))
                         (insert (if (buffer-modified-p buffer)
                                     ?\*
                                   ?\ ))
                         (insert (if ro
                                     ?\%
                                   ?\ ))
                         (if (string-match "[\n\"\\ \t]" name)
                             (let ((print-escape-newlines t))
                               (prin1 name output))
                           (insert ?\  name))
                         (indent-to col1 1)
                         (cond ((stringp id)
                                (insert id))
                               (id
                                (set-buffer buffer)
                                (condition-case e
                                    (funcall id output)
                                  (error
                                   (princ "***" output) (prin1 e output)))
                                (set-buffer output)
                                (goto-char (point-max)))))
                       (insert ?\n)))))
            (setq buffer-read-only t))))
      (if (not (bufferp current))
          (save-excursion
            (set-buffer output)
            (goto-char current))))))

(defun buffer-menu (arg)
  "Make a menu of buffers so you can save, delete or select them.
With argument, show only buffers that are visiting files.
Type ? after invocation to get help on commands available.
Type q immediately to make the buffer menu go away."
  (interactive "P")
  (list-buffers arg)
  (pop-to-buffer "*Buffer List*")
  (forward-line 2)
  (message
   "Commands: d, s, x; 1, 2, m, u, q; delete; ~;  ? for help."))

(defun Buffer-menu-mark ()
  "Mark buffer on this line for being displayed by \\[Buffer-menu-select] command."
  (interactive)
  (beginning-of-line)
  (if (looking-at " [-M]")
      (ding)
    (let ((buffer-read-only nil))
      (delete-char 1)
      (insert ?>)
      (forward-line 1))))

(defun Buffer-menu-unmark ()
  "Cancel all requested operations on buffer on this line."
  (interactive)
  (beginning-of-line)
  (if (looking-at " [-M]")
      (ding)
    (let* ((buf (Buffer-menu-buffer t))
	   (mod (buffer-modified-p buf))
	   (readonly (save-excursion (set-buffer buf) buffer-read-only))
	   (buffer-read-only nil))
      (delete-char 3)
      (insert (if readonly (if mod " *%" "  %") (if mod " * " "   ")))))
  (forward-line 1))

(defun Buffer-menu-backup-unmark ()
  "Move up and cancel all requested operations on buffer on line above."
  (interactive)
  (forward-line -1)
  (Buffer-menu-unmark)
  (forward-line -1))

(defun Buffer-menu-delete ()
  "Mark buffer on this line to be deleted by \\[Buffer-menu-execute] command."
  (interactive)
  (beginning-of-line)
  (if (looking-at " [-M]")		;header lines
      (ding)
    (let ((buffer-read-only nil))
      (delete-char 1)
      (insert ?D)
      (forward-line 1))))

(defun Buffer-menu-delete-backwards ()
  "Mark buffer on this line to be deleted by \\[Buffer-menu-execute] command
and then move up one line"
  (interactive)
  (Buffer-menu-delete)
  (forward-line -2)
  (if (looking-at " [-M]") (forward-line 1)))

(defun Buffer-menu-save ()
  "Mark buffer on this line to be saved by \\[Buffer-menu-execute] command."
  (interactive)
  (beginning-of-line)
  (forward-char 1)
  (if (looking-at " [-M]")		;header lines
      (ding)
    (let ((buffer-read-only nil))
      (delete-char 1)
      (insert ?S)
      (forward-line 1))))

(defun Buffer-menu-not-modified ()
  "Mark buffer on this line as unmodified (no changes to save)."
  (interactive)
  (save-excursion
    (set-buffer (Buffer-menu-buffer t))
    (set-buffer-modified-p nil))
  (save-excursion
   (beginning-of-line)
   (forward-char 1)
   (if (looking-at "\\*")
       (let ((buffer-read-only nil))
	 (delete-char 1)
	 (insert ? )))))

(defun Buffer-menu-execute ()
  "Save and/or delete buffers marked with \\[Buffer-menu-save] or \\[Buffer-menu-delete] commands."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (forward-line 1)
    (while (re-search-forward "^.S" nil t)
      (let ((modp nil))
	(save-excursion
	  (set-buffer (Buffer-menu-buffer t))
	  (save-buffer)
	  (setq modp (buffer-modified-p)))
	(let ((buffer-read-only nil))
	  (delete-char -1)
	  (insert (if modp ?* ? ))))))
  (save-excursion
    (goto-char (point-min))
    (forward-line 1)
    (let ((buff-menu-buffer (current-buffer))
	  (buffer-read-only nil))
      (while (search-forward "\nD" nil t)
	(forward-char -1)
	(let ((buf (Buffer-menu-buffer nil)))
	  (or (eq buf nil)
	      (eq buf buff-menu-buffer)
	      (save-excursion (kill-buffer buf))))
	(if (Buffer-menu-buffer nil)
	    (progn (delete-char 1)
		   (insert ? ))
	  (delete-region (point) (progn (forward-line 1) (point)))
 	  (forward-char -1))))))

(defun Buffer-menu-select ()
  "Select this line's buffer; also display buffers marked with \">\".
You can mark buffers with the \\[Buffer-menu-mark] command."
  (interactive)
  (let ((buff (Buffer-menu-buffer t))
	(menu (current-buffer))	      
	(others ())
	tem)
    (goto-char (point-min))
    (while (search-forward "\n>" nil t)
      (setq tem (Buffer-menu-buffer t))
      (let ((buffer-read-only nil))
	(delete-char -1)
	(insert ?\ ))
      (or (eq tem buff) (memq tem others) (setq others (cons tem others))))
    (setq others (nreverse others)
	  tem (/ (1- (screen-height)) (1+ (length others))))
    (delete-other-windows)
    (switch-to-buffer buff)
    (or (eq menu buff)
	(bury-buffer menu))
    (while others
      (split-window nil tem)
      (other-window 1)
      (switch-to-buffer (car others))
      (setq others (cdr others)))
    (other-window 1)))			;back to the beginning!

(defun Buffer-menu-visit-tags-table ()
  "Visit the tags table in the buffer on this line.  See `visit-tags-table'."
  (interactive)
  (let ((file (buffer-file-name (Buffer-menu-buffer t))))
    (if file
	(visit-tags-table file)
      (error "Specified buffer has no file"))))

(defun Buffer-menu-1-window ()
  "Select this line's buffer, alone, in full screen."
  (interactive)
  (switch-to-buffer (Buffer-menu-buffer t))
  (bury-buffer (other-buffer))
  (delete-other-windows))

(defun Buffer-menu-this-window ()
  "Select this line's buffer in this window."
  (interactive)
  (switch-to-buffer (Buffer-menu-buffer t)))

(defun Buffer-menu-other-window ()
  "Select this line's buffer in other window, leaving buffer menu visible."
  (interactive)
  (switch-to-buffer-other-window (Buffer-menu-buffer t)))

(defun Buffer-menu-2-window ()
  "Select this line's buffer, with previous buffer in second window."
  (interactive)
  (let ((buff (Buffer-menu-buffer t))
	(menu (current-buffer))
	(pop-up-windows t))
    (switch-to-buffer (other-buffer))
    (pop-to-buffer buff)
    (bury-buffer menu)))


;;; mouseability

(defun Buffer-menu-mouse-select (event)
  (interactive "e")
  (mouse-set-point event)
  (Buffer-menu-select))

(defvar Buffer-menu-popup-menu
  '("Buffer Commands"
    ["Select Buffer"			Buffer-menu-select		t]
    ["Select buffer Other Window"	Buffer-menu-other-window	t]
    ["Clear Buffer Modification Flag"	Buffer-menu-not-modified	t]
    "----"
    ["Mark Buffer for Selection"	Buffer-menu-mark		t]
    ["Mark Buffer for Save"		Buffer-menu-save		t]
    ["Mark Buffer for Deletion"		Buffer-menu-delete		t]
    ["Unmark Buffer"			Buffer-menu-unmark		t]
    "----"
    ["Delete/Save Marked Buffers"	Buffer-menu-execute		t]
    ))

(defun Buffer-menu-popup-menu (event)
  (interactive "e")
  (mouse-set-point event)
  (beginning-of-line)
  (let ((buffer (Buffer-menu-buffer nil)))
    (if buffer
	(popup-menu
	 (nconc (list (car Buffer-menu-popup-menu)
		      (concat
		       "Commands on buffer \"" (buffer-name buffer) "\":")
		      "----")
		(cdr Buffer-menu-popup-menu)))
      (error "no buffer on this line"))))
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