Re: [RFC/PATCH] clone: introduce clone.submoduleGitDir to relocate $GITDIR

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 15, 2013, 09:45 UTC
Message-ID: <7vfvys160z.fsf@alter.siamese.dyndns.org>
In-Reply-To: <CALkWK0mvtRhFc0_4883ATNaYpb+kDwpV9VxeAoqJy5HxNQ6vgg@mail.gmail.com>

Ramkumar Ramachandra <artagnon@gmail.com> writes:

Show 11 quoted lines

> Junio C Hamano wrote:
>> Any new configuration variable brings its own problem by forcing
>> existing users to countermand it explicitly from the command line.
>> If the --separate-git-dir would not work for your application, you
>> need a new feature and you can achieve the same by adding a new
>> command line option (say, --submodule-git-dir), that would be more
>> preferrable.
>
> I'm getting a little tired of your first instinct to oppose every new
> addition to git. (Ofcourse I understand your attitude as the
> maintainer, but still)

It was purly about "do not add anything that makes no sense." and not about "oppose all new addition."

When you add a submodule with the current system, bypassing "git submodule add", you can either

    (1) "git clone $URL here" and then "git add here"; or
    (2) "git init here" and then "git add here".

Because you didn't say what you are aiming for in the grander picture, I thought you were "making the UI simpler" by making it unnecessary for the users to say "git clone" himself as a separate step before doing "git add". In such a world, "add" would internally run "clone". If that were the case (I now know it is not), then the configuration _is_ unnecessary, and it is perfectly valid to question why you thought it is needed.

If your plan is instead to keep "git clone" followed by "git add" as the pattern for use case (1), teaching "clone" to automatically use the --separate-git-dir mechanism to point at the right place inside the $GIT_DIR of the superproject does make sense to help the use case.

But if that is the direction you are aiming for, would it be possible that the same configuration variable can and should cover the use case (2) as well? After all, between "git init here" and "git add here", the user may say (cd here && git pull $URL) and the expected end result would be the same as (1), no?

I do not recall the details of the codepaths involved offhand, but when you "git clone $URL [here]", after running "mkdir here", it would create a $GIT_DIR for the "here" repository in "here/.git" (and with --separate-git-dir, it would create it elsewhere and drop gitfile at "here/.git"). When you "git init here", after running "mkdir here", the same thing happens.

How common are these two implementations?

If "clone" just calls init_db(), I would imagine that it might be trivial to cover both cases by telling init_db() to pay attention to the configuration, without doing much in the "clone" itself.