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From: liberte@uiucdcsb.cs.uiuc.edu
Newsgroups: comp.emacs
Subject: Re: (treat-as-single-undo)
Message-ID: <165400024@uiucdcsb>
Date: Wed, 2-Sep-87 12:11:00 EDT
Article-I.D.: uiucdcsb.165400024
Posted: Wed Sep  2 12:11:00 1987
Date-Received: Sat, 5-Sep-87 08:26:26 EDT
References: <4300001@uiucdcsm>
Lines: 50
Nf-ID: #R:uiucdcsm:4300001:uiucdcsb:165400024:000:1438
Nf-From: uiucdcsb.cs.uiuc.edu!liberte    Sep  2 11:11:00 1987


In an attempt to satisfy Mr. Grunwald's desire for undo chunking, I
wrote the following code which curiously does not work.  It would work
if the undo-boundary command were changed from a primitive to a lisp
funciton.  I see no other reasonable way to chunk undos with standard
GNU Emacs.

dan
-----

(defvar undo-chunk-list nil
  "List of (hopefully) unique information corresponding to each chunk
of changes.  With this version, the undo-boundary-count is used.")
(make-variable-buffer-local 'undo-chunk-list)

(defvar undo-boundary-count 0
  "Count of undo-boundary calls since the last undo-chunk")
(make-variable-buffer-local 'undo-boundary-count)


(fset 'primitive-undo-boundary (symbol-function 'undo-boundary))

(defun undo-boundary ()
  "Substitue for the primitive undo-boundary to count undo boundaries"
  (setq undo-boundary-count (1+ undo-boundary-count))
;  (message "undo-boundary %d" undo-boundary-count)
  (primitive-undo-boundary)
  )


(defun mark-undo-chunk
  "Add undo-chunk info to undo-chunk-list."
  (setq undo-chunk-list (cons undo-boundary-count undo-chunk-list))
  (setq undo-boundary-count 0)
  )

(defun undo-chunk (n)
  "Undo N chunks of undos."
  (interactive "p")
  (if (> 0 n)
      (progn
	(undo-more undo-boundary-count)
	(setq n (1- n))))
    
  (while (and undo-chunk-list (> n 0))
    (undo-more (car undo-chunk-list))
    (setq undo-chunk-list (cdr undo-chunk-list))
    (setq n (1- n))
    )
  )