Re: Intricacies of submodules

["Ping Yin" <pkufranky@gmail.com>]

On Sat, Apr 12, 2008 at 1:25 PM, Junio C Hamano <gitster@pobox.com> wrote:
> "Ping Yin" <pkufranky@gmail.com> writes:
>
>
> >>  After working with the project for a while (i.e. you pull and perhaps push
>  >>  back or send patches upstream), .gitmodules file changes and it now says
>  >>  the repository resides at host B.xz because the project relocated.  You
>  >>  would want the next "git submodule update" to notice that your .git/config
>  >>  records a URL you derived from git://A.xz/project.git/, and that you have
>  >>  not seen this new URL git://B.xz/project.git/, and give you a chance to
>  >>  make adjustments if needed.
>  >
>  > I think this should be done if "git submodule update" fails. The
>  > reason it fails may be different, such as newest commits not pushed
>  > out and the subproject relocated etc. So it can only given some hints
>  > with "maybe".
>  >
>  > However, how to detect the url has changed in .gitmodules? Compare the
>  > latest two version of .gitmodules?
>
>  That's why I suggested (and Roman seems to have got it, so I do not think
>  what I wrote was too confusing to be understood) you should record the set
>  of _all_ URLs you have _seen_ in .git/config.  If the URL in .gitmodules
>  checked out is included in that set, you do not do anything.  Otherwise
>  you ask.

I don't think it deserves such a change (say recoding history urls to
$GIT_DIR/config) to just ask just the user whether to change url in
$GIT_CONFIG/config when the url in .gitmodules changes to a new one.

Actually, i think this is an ugly solution :-)

>
>  I think "git submodule update" is a good place to do that check, but I'd
>  prefer it be done _before_ it actually goes to the network to start
>  accessing potentially stale URL.  The old URL may not be defunct but the
>  project decided not to advertise it to be used for some non-technical
>  reason (e.g. the site owner asked them not to point at it and instead use
>  some other mirrors).

If only the protocol (such as http://->git://) is different between
urls in $GIT_DIR/config and .gitmodules, i think use
"url.base.insteadOf = newbase" is simpler.

If the urls are totally different, when url in .gitmodules changes,
there is little chance that the url in $GIT_DIR/config will also
change.


-- 
Ping Yin