I recently spent a few days writing some tricky bit-twiddling code to implement a radix tree. I found myself making many programming mistakes, and I thought it would be interesting to study them, examine their contributing factors, and think how each of them could be prevented.
As a step toward this direction I wrote a small vim script that walks back in the editor's undo history, saving a snapshot of the file after each change. Unfortunately, after an ungraceful shutdown (or crash; I am not sure) of Windows, I lost the editor's session (about 400 changes), and I was thus unable to complete my study. I am including here the script, in the hope that somebody else will find it useful.
" " :source this vim script to generate a log of all changes to the file " being edited. The script will create a directory named by appending " .log to the name of the file, and save in it numbered files, representing " the snapshot of the file before each change. A separate file, named " log, contains the timestamp of each change. " " Copyright (c) 2008, Diomidis Spinellis. All rights reserved. " " Redistribution and use in source and binary forms, with or without " modification, are permitted provided that the following conditions " are met: " 1. Redistributions of source code must retain the above copyright " notice, this list of conditions and the following disclaimer. " 2. Redistributions in binary form must reproduce the above copyright " notice, this list of conditions and the following disclaimer in the " documentation and/or other materials provided with the distribution. " " THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND " ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE " IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE " ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE " FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL " DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS " OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) " HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT " LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY " OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF " SUCH DAMAGE. call mkdir(expand('%') . ".log") let s:current = changenr() let s:log =  while 1 let s:n = changenr() redir @a echo "Change: " s:n "\n" undo redir END if match(@a, 'Already at oldest change') != -1 break endif let s:log = add(s:log, @a) execute "write " . expand("%") . ".undo/" . s:n endwhile call writefile(s:log, expand("%") . ".log/log") execute "undo " . s:current
Last modified: Monday, August 25, 2008 4:32 pm
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