Re: [PATCH 0/3] Teach Git about the patience diff algorithm

[Jeff King <peff@peff.net>]

On Fri, Jan 02, 2009 at 02:39:04PM -0500, Jeff King wrote:

> If you just want to see the results on some real-world cases (and don't
> care about measuring performance), try installing bzr and using their
> patiencediff test program as a GIT_EXTERNAL_DIFF.
> 
> On Debian, it's:
> 
>   $ sudo apt-get install bzr
>   $ cat >$HOME/patience <<'EOF'
>     #!/bin/sh
>     exec python /usr/share/pyshared/bzrlib/patiencediff.py "$2" "$5"
>     EOF
>   $ chmod 755 patience
>   $ GIT_EXTERNAL_DIFF=$HOME/patience git diff

For added fun, try this:

-- >8 --
#!/bin/sh

canonical() {
  grep '^[ +-]' | egrep -v '^(---|\+\+\+)'
}

git rev-list --no-merges HEAD | while read rev; do
  git diff-tree -p $rev^ $rev | canonical >git.out
  GIT_EXTERNAL_DIFF=$HOME/patience git diff $rev^ $rev | canonical >bzr.out
  echo "`diff -U0 git.out bzr.out | wc -l` $rev"
done
-- 8< --

I'm running it on git.git now. It looks like both algorithms return the
same patch for most cases. Some of the differences are interesting,
though.

For example, f83b9ba209's commit message indicates that it moves the
"--format-patch" paragraph. Which is what "git diff" shows. Patience
diff shows it as moving other text _around_ that paragraph.

-Peff