Re: [PATCH 07/16] git-read-tree: take --submodules option

On Fri, May 18, 2007 at 08:59:48PM -0700, Junio C Hamano wrote:

Now, suppose "git checkout" needs to recurse into one
subdirectory that is to have a subproject.  There are three
cases:

 (1) There is no git repository yet (the plumbing layer already
     makes sure there is a directory, but does not do anything
     else).

 (2) There already is a git repository there, which is the
     correct repository (perhaps determined by .gitmodules and
     .git/config in the superproject, or presense of the commit
     that is recorded in the superproject's index).

 (3) There is a git repository but it is not the correct one.

We've discussed in the other thread about what to do in case
(1) to some degree.

For case (2), I think what should happen there is an equivalent
of this:

	$ commit=$(git-rev-parse :subproject)
        $ cd subproject
	$ git-rev-parse --verify $commit || git fetch || barf
        $ git checkout $commit

Does everyone agree that we should fetch (possibly after asking
for confirmation from the use) _during_ the checkout ?
I now only fetch submodules during a fetch of the supermodule
(actually, in my current patch set, I only fetch a submodule
the first time I see it, but that's a bug), but if there is
a consensus on this, I can switch to fetching during checkout.

As to the key to use to lookup the URL in the config, right
now I simply use the directory name where it is attached
(which seems like a useful default to me).
I'm not all that convinced that we should store a default URL
in history, so AFAICS, the only thing we need to store is a
mapping between directory names and subproject names.
It has been suggested to do that in .gitattributes.
Is that OK for everyone, or do we really need a separate .gitmodules ?

skimo