Re: weird diff output?

From: Jeff King <peff@peff.net>
Date: Apr 14, 2016, 18:34 UTC
Message-ID: <20160414183405.GE22068@sigill.intra.peff.net>
In-Reply-To: <alpine.DEB.2.10.1604140639230.8340@zino>

On Thu, Apr 14, 2016 at 06:56:39AM -0700, Davide Libenzi wrote:

Show 10 quoted lines

> That was a zillions of years ago :) , but from a quick look at email
> thread, if you want to do it within xdiff, xdi_change_compact would be
> the place.  The issue is knowing in which situations one diff look
> better than another, and embedding an if-tis-do-tat logic deep into
> the core diff machinery.  In theory one could implement the same thing
> higher up, working with the unified diff text format, where maybe a
> user can provide its own diff post-process hook script.  In any case,
> that still leaves open the issue on what to shift in the diff chunks,
> and in which cases. Which is likely going to be language/format
> dependent. IMHO, it gets nasty pretty quickly.

Thanks, that's helpful. Stefan already came up with a heuristic that I implemented as a post-processing script in perl. It _seems_ to work pretty well in practice across multiple languages, so our next step was to implement it in an actual usable and efficient way. :)

Looking over the code, I agree that xdl_change_compact() is the place we would want to put it. We'd probably tie it to a command-line option and let people play around with it, and then consider making it the default if there's widespread approval.

-Peff