From: Jeff King <peff@peff.net>
To: Stefan Beller <sbeller@google.com>
Cc: git@vger.kernel.org, jacob.keller@gmail.com, mhagger@alum.mit.edu
Subject: Re: [PATCH] diff compaction heuristic: favor shortest neighboring blank lines
Date: Fri, 17 Jun 2016 11:36:38 -0400 [thread overview]
Message-ID: <20160617153637.GA9314@sigill.intra.peff.net> (raw)
In-Reply-To: <20160616174620.1011-1-sbeller@google.com>
On Thu, Jun 16, 2016 at 10:46:20AM -0700, Stefan Beller wrote:
> The compaction heuristic for diffs was deemed quite good, but in 5580b27
> we have an example demonstrates a common case, that fails with the existing
> heuristic. That is why we disabled the heuristic in the v2.9.0 release.
>
> With this patch a diff looks like:
>
> def bar
> do_bar_stuff()
>
> common_ending()
> end
>
> + def bal
> + do_bal_stuff()
> +
> + common_ending()
> + end
> +
> def baz
> do_baz_stuff()
>
> common_ending()
> end
>
> whereas before we had:
>
> WIP (TODO: ask peff to provide an example that actually triggers, I seem to be
> unable to write one, though I thought the above was one)
Did you want something that triggers the "bad" case with the existing
compaction heuristic?
I gave one in:
http://article.gmane.org/gmane.comp.version-control.git/296947
I think the difference is that in my example, the diff (before
compaction) has the blank line at the top (because we are adding a new
entry at the bottom), whereas in yours, the blank line is at the bottom.
This patch does make my "bad" case look better. Unfortunately, it
re-breaks another case:
cat >file.rb <<\EOF
##
# This is the foo function.
def foo
foo stuff
end
##
# This is the bar function.
def bar
bar stuff
end
##
# This is the baz function.
def baz
baz stuff
end
EOF
git init
git add file.rb
sed -i 7,12d file.rb
git diff
That goes back to the original, pre-compaction-heuristic diff:
diff --git a/file.rb b/file.rb
index 0b31fb6..ee25d63 100644
--- a/file.rb
+++ b/file.rb
@@ -5,12 +5,6 @@ def foo
end
##
-# This is the bar function.
-def bar
- bar stuff
-end
-
-##
# This is the baz function.
def baz
baz stuff
-Peff
next prev parent reply other threads:[~2016-06-17 15:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 17:46 [PATCH] diff compaction heuristic: favor shortest neighboring blank lines Stefan Beller
2016-06-16 20:27 ` Junio C Hamano
2016-06-16 21:06 ` Stefan Beller
2016-06-16 21:10 ` Michael Haggerty
2016-06-16 21:36 ` Stefan Beller
2016-06-17 15:36 ` Jeff King [this message]
2016-06-17 16:09 ` Stefan Beller
2016-06-23 17:10 ` Michael Haggerty
2016-06-23 17:25 ` Stefan Beller
2016-06-23 17:37 ` Junio C Hamano
2016-06-23 20:13 ` Michael Haggerty
2016-06-30 13:54 ` Michael Haggerty
2016-07-01 17:04 ` diff heuristics dramatically improved by considering line indentation and " Michael Haggerty
2016-07-01 18:01 ` [PATCH] diff compaction heuristic: favor shortest neighboring " Junio C Hamano
2016-07-04 14:33 ` Jakub Narębski
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