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

On Tue, Jun 18, 2013 at 7:23 PM, Jeff King [off-list ref] wrote:

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

quoted

[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.

Yes, that was probably it. I tried to find a gmail configuration, but
I now discover it is done per-email, not globally. Apologies. I have
forwarded the original to Thomas, but based on current feedback, it
seems not worth re-sending the original mail to the list. See below.

quoted

quoted

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.

My choice of "permit" in the description was not best. My
implementation showed a word-based diff, but preserved the existing
mechanism for actually applying the hunk. I understand the way
colorization in git-add--interactive.perl works right now is to
colorize one version to display and use another - I think I preserved
that. I intended to permit the user to choose to show a word-based
diff of a patch during interactive add.

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

Hmm, I will have to re-consider the implications on that kind of
workflow. Thanks!

"git add foo"). But it does save keystrokes if your workflow is to
simply "add -p" everything to double-check it before adding.

Yes, that was what I was aiming to make easier.

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).

Good point. What I think I really want is "git add
--interactive=color" (with or without --patch) to permit the user to
choose to see the (colorized) word-based diff when they want one. I
now see that the config file approach in my proposed patch doesn't go
close enough to that to be worth considering further.

I think a proper implementation of the above command would have to
* add something to builtin_add_options in builtin/add.c,
* set a new static variable in add.c, and
* extend the calling logic for interactive_add() and/or
run_add_interactive() accordingly,
so that the perl script can get the user's choice on the command line
and not from a config file. And only respond when colorization is
configured.

Does --patch=color, --interactive=color or adding new option
--color-words make more sense?

I'll have a think about that and get back to you guys.

Thanks!

Mark

-Peff