Re: [PATCH] git-add--interactive.perl: Permit word-based diff

[Jeff King <peff@peff.net>]

On Tue, Jun 18, 2013 at 09:22:16AM +0200, Thomas Rast wrote:

> [I don't seem to have received a copy of the original mail, so I can
> only guess...]

Yes, the original doesn't seem to have made it to the list. Sorry, I
don't have a copy (I am in the habit of deleting direct mails that are
cc'd to the list, as I keep a separate list archive).

Mark, did you happen to send an HTML mail? The list will silently
reject such mail.

> > Note that the number of lines in your --word-diff=color hunk and the
> > actual diff will not necessarily be the same.  What happens if I split a
> > hunk with your patch?
> 
> If it's actually what you hint at, there's another problem: the word
> diff might not even have the same number of hunks.  For example, a
> long-standing bug (or feature, depending on POV) of word-diff is that it
> does not take opportunities to completely drop hunks that did not make
> any word-level changes.

Yeah, I didn't even think of that.

In general, I think one can assume 1-to-1 correspondence between whole
regular diffs and whole word-diffs, but not below that (i.e., neither a
correspondence between hunks nor between lines).

With something like contrib/diff-highlight, you get some decoration, and
can assume a 1-to-1 line correspondence.

However, I think that when reviewing text (especially re-wrapped
paragraphs) that word-diff can be much easier to read, _because_ it
throws away the line correspondence. To be correct, though, I think we
would have to simply show the whole word-diff for a file and say "is
this OK?". Which sort of defeats the purpose of "add -p" as a hunk
selector (you could just as easily run "git diff --color-words foo" and
"git add foo"). But it does save keystrokes if your workflow is to
simply "add -p" everything to double-check it before adding.

So I dunno. I could see myself using it, but I certainly wouldn't want a
config variable that turns it on all the time (which is what the
original patch did).

-Peff