Re: v2.11 new diff heuristic?

From: Jacob Keller <jacob.keller@gmail.com>
Date: Nov 22, 2016, 17:18 UTC
Message-ID: <502984B2-1ADF-4BEC-9C5D-057AADAA7C61@gmail.com>
In-Reply-To: <CAHd499AjXh1YnVgBj_8j0fgvOgOn53y+sPBBy6y7mSM-+dCyVw@mail.gmail.com>

On November 22, 2016 6:42:36 AM PST, Robert Dailey <rcdailey.lists@gmail.com> wrote:

Show 21 quoted lines

>The release notes mention a new heuristic for diff:
>
>* Output from "git diff" can be made easier to read by selecting
>which lines are common and which lines are added/deleted
>intelligently when the lines before and after the changed section
>are the same. A command line option is added to help with the
>experiment to find a good heuristics.
>
>However, it lacks information on exactly how to use this new feature.
>I dug into the git diff documentation here:
>
>https://git-scm.com/docs/git-diff
>
>It mentions a "--compaction-heuristic" option. Is this the new
>heuristic outlined by the release notes? If not, which is it? Is the
>compaction heuristic compatible with the histogram diff algorithm? Is
>there a config option to turn this on all the time? For that matter,
>is this something I can keep on all the time or is it only useful in
>certain situations?
>
>There's still so much more about this feature I would like to know.

Hi,

Yes for now the compaction heuristic option has an undocumented config. (I forget the exact name off the top of my head). Currently it is being evaluated and likely we want to make it default in the near future once we are certain that it helps and doesn't make any difference worse.

So long term you will not need any special knobs to benefit.

Thanks, Jake