Re: [RFC] Third round of support for cloning submodules

From: Sven Verdoolaege <skimo@kotnet.org>
Date: May 20, 2007, 19:59 UTC
Message-ID: <20070520195930.GX942MdfPADPa@greensroom.kotnet.org>
In-Reply-To: <7vhcq7l3ar.fsf@assigned-by-dhcp.cox.net>

On Sun, May 20, 2007 at 12:10:04PM -0700, Junio C Hamano wrote:

Show 7 quoted lines

> > bash-3.00$ ./git-config --remote=http://www.liacs.nl/~sverdool/isa.git --get-regexp 'submodule\..*\.url' 
> > submodule.cloog.url /home/sverdool/public_html/cloog.git
> > submodule.cloog.url http://www.liacs.nl/~sverdool/cloog.git
> 
> You are priming the process by having these configuration
> variables in the superproject to be cloned (i.e. this is done by
> the owner of the superproject).

Is that a question? The answer would be that if the user didn't put this information in a config file, then git will try to get the information from any remote it can get its hands on.

Show 5 quoted lines

> What's the design like to make clone and checkout work together?
> When you run the first clone with -n ("do not checkout"), what
> should happen (I am not asking what your code does, but what the
> desired behaviour should be)?  My take on that question is
> "subproject cloning is done by checkout, not clone".

Then I guess you are not asking me. I took the suggestion of doing the subproject cloning during checkout from you.

Show 5 quoted lines

> I am very worried about this big red switch that says "all
> subprojects to be cloned and checked out, or nothing".  I think
> this would not work well with projects that truly need
> superproject support (i.e. very large ones, where most people
> would not want to clone and check out every single subproject).

It's pretty easy to add a "submodule.*.skip" or "submodule.*.ignore". Since the subcloning only happens at checkout, you could set these before doing a checkout.

Show 10 quoted lines

> > I currently do not fetch after the initial clone, since
> > I'm not sure what ref to use for the revision I need to
> > fetch for the supermodule.
> 
> I think fetching inside the subproject can be safely done with
> the default (i.e. refs/heads/*:refs/remotes/origin/*) of 1.5.0
> or later, as long as we tell the users of the feature that they
> should make sure that the commit referenced by superproject tree
> entries are available with such a fetch, which is a sane thing
> to require anyway.

Seems like a pretty strict requirement, but it's easy to implement, so I guess I can do that in the fourth version.

Show 10 quoted lines

> The more important issue I think is at what point in the
> superproject operation does a recursive checkout in a subproject
> should happen, and how we should do the checkout.  Issues I can
> think of offhand are (no way exhaustive):
> 
>  - Do we checkout a branch? if so which one?
> 
>  - Do we detach HEAD if the commit named by the superproject
>    tree is not at the tip of the current branch of subproject?
>    do we detach always even if the commit is at the tip?

I thought there was a consensus to detach the HEAD. I don't have a strong opinion on this issue, but a detached HEAD seems the most appropriate to me.

>  - What would we do when the subproject working tree is not
>    clean?

I was planning on adding a --dry-run to git-checkout. The superproject would run this in each subproject before doing the actual checkout of the superproject.

Show 6 quoted lines

>  - How can a user decide which subproject to descend into and
>    which subproject to ignore, and how does git remember the
>    earlier decision made by the user without asking the same
>    again, and how does a user express "now I want to also track
>    that subproject I've ignored so far" and "now I am not
>    interested in following that subproject anymore"?

Just twiddle the "submodule.*.skip" option.

> So I tend to disagree with not having the indirection we
> discussed on the other thread about .gitmodules, but I consider
> it a minor detail of cloning, and it is not a major deal to me.

Some form of indirection is definitely required (although not for my use of submodules) and I'll probably add it in a future round.

skimo