Re: v2.11 new diff heuristic?

From: Stefan Beller <sbeller@google.com>
Date: Nov 22, 2016, 17:51 UTC
Message-ID: <CAGZ79kbJ1vM=wd+53RezKEuucBCG96rL7dNhZpqR6m+brRAJ=w@mail.gmail.com>
In-Reply-To: <CAHd499AjXh1YnVgBj_8j0fgvOgOn53y+sPBBy6y7mSM-+dCyVw@mail.gmail.com>

On Tue, Nov 22, 2016 at 6:42 AM, Robert Dailey <rcdailey.lists@gmail.com> wrote:

Show 15 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?

yes.

> Is the
> compaction heuristic compatible with the histogram diff algorithm?

yes as the compaction heuristic is applied after the actual diff is performed.

> 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?

I think you can set diff.compactionHeuristic and it will use it by default.

>
> There's still so much more about this feature I would like to know.

The background story (and what this new compaction heuristic is doing) is found at https://github.com/mhagger/diff-slider-tools