Re: git-diff on touched files: bug or feature?

From: Matthieu Moy <matthieu.moy@imag.fr>
Date: Aug 2, 2007, 09:23 UTC
Message-ID: <vpqhcni47ek.fsf@bauges.imag.fr>
In-Reply-To: <7v4pjj5fp6.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano <gitster@pobox.com> writes:

Show 21 quoted lines

> Matthieu Moy <Matthieu.Moy@imag.fr> writes:
>
>> $ touch bar
>> $ git diff
>> diff --git a/bar b/bar         <--- here ---<
>> $ git status
>> # On branch master
>> nothing to commit (working directory clean)
>> $ git diff                     <--- status updated
>>                                     the stat in the index.
>>
>> Is this intended,
>
> Yes.  Very much so, intentionally, from very early days of git.
> This serves as a reminder to the user that he started editing
> but changed his mind to end up with the same contents as the
> original, until the next "update-index --refresh" (which is
> internally invoked from "status").
>
> If the feature still makes sense in the modern world is a
> different story, but I do find it useful.

I understand that it can be usefull, but I really don't like having it by default (is there a way to deactivate it BTW?):

I've hit this while working on a project, doing a lot of modifications through scripting (some regexp substitutions and such kinds of things). Then, git-diff shows me pages of "diff --git ...", and a few relevant entries in the middle of it. That's very bad from the usability point of view (I actually had some ~20 lines diff surrounded by 100+ irrelevant lines), and also kills performance: if a script touches a lot of files, I expect the next "diff" or "status" to be slow, but not the second next. Here, diff will be slow until I run git-status again.

And I find the "reminder" feature very fragile. That means git-status is no longer a read-only operation for the user. As a user, I expect to be able to run git-status without changing the behavior of subsequent git commands, which is not the case here. That means for example that someone used to running git-diff /before/ git-status will get the reminder, while someone used to running git-diff /after/ git-status (which I find sensible, get an overview before getting the details of what you did) won't get it. Note also that this makes a difference between git-status (which updates the stat in the index) and git-status -a (which doesn't). That's an implementation detail that shouldn't be exposed to the user.

Since I don't see any mention of this in the man pages for git-diff or git-status (I might have missed it), I wonder how many user actually ever used this as a feature.

I'd be in favor of disabling this by default, and providing a configuration option and/or a command line option to diff to enable it. I can try writting a patch for this if people agree on the specification.

-- 
Matthieu