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From: Kyle Jones <kyle_jones@wonderworks.com>
To: xemacs-beta@xemacs.org
Subject: undo/redo models [was: Is your (favorite) package not in XEmacs and should be?]
In-Reply-To: <199702161727.AA223974023@martigny.ai.mit.edu>
References: <199702161727.AA223974023@martigny.ai.mit.edu>

Bill Dubuque writes:
 > The debate over the various types of undo/redo models has a
 > very long history.  As I mentioned a long time ago here, there
 > is a very good discussion of such in the following book which,
 > more generally, provides a good introduction to UI design from
 > a formal (math) perspective:
 > 
 >  Thimbleby, Harold.  User interface design / New York, N.Y.
 >  ACM Press ; Wokingham, England ; Reading, Mass. :
 >  Addison-Wesley Pub., c1990. xxiii, 470 p. : ill. ; 24 cm. LC
 >  CALL NUMBER: QA76.9.U83 T48 1990 Thimbleby's Home Page:
 >  http://www.cs.mdx.ac.uk/harold
 > 
 > It is quite difficult to design a good undo/redo mechanism. If
 > you haven't though hard about it for at least a week then it
 > is unlikely you've invested enough effort.

Thumping down a 470 page book is kind of offputting when
discussing an afternoon's hack, don'tcha think? :) Time
constraints require that I take the hobbyist approach to most
Emacs projects that I do, with perhaps VM being the only
exception since I run mail systems for a living.  I leave it to
the folks who hack Emacs for a living to decide whether undo/redo
is worth including or not.  I'll be happy with the decision,
either way.

I do appreciate the reference information.

