Re: [PATCH] Documentation/diff-options: explain different diff algorithms

From: Stefan Beller <sbeller@google.com>
Date: Aug 9, 2018, 19:26 UTC
Message-ID: <CAGZ79kZR_gj00JORH3WB_T+_mgtQm5PGt6+DSMFUbJM+C4FxVw@mail.gmail.com>
In-Reply-To: <xmqq600mmaqn.fsf@gitster-ct.c.googlers.com>

On Tue, Aug 7, 2018 at 8:56 AM Junio C Hamano <gitster@pobox.com> wrote:

Show 11 quoted lines

>
> Jonathan Nieder <jrnieder@gmail.com> writes:
>
> > Both don't seem quite right, since they have an extra space before the
> > period.  The git-diff(1) seems especially not quite right --- does it
> > intend to say something like "See the DIFF ALGORITHMS section for more
> > discussion"?
>
> Good suggestion and doing so would nicely allow side-stepping the
> space before the dot issue, i.e. "See the DIFF ALGO section (in
> git-diff(1)) for more discussion".   I like it.

Me, too.

Show 8 quoted lines

> >> +`Histogram`
> >> +
> >> +This algorithm finds the longest common substring and recursively
> >> +diffs the content before and after the longest common substring.
>
> As a first-time reader, I felt that it is a bit uneven that there is
> no attribution for only this item, unlike the description for Myers
> and Patience.

Yeah. That is because I spent too much time thinking how this algo is flawed (in its design as the comments in the initial commit in JGit indicate that design error when reading closely) when I was trying to understand it deeply.

Maybe I should emphasize the trade off for performance gain more as Shawn really cared about performance. After all it offers the best performance in *many* common cases, but has a "long tail" of really unfortunate results, too.