Re: tracking submodules out of main directory.

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 27, 2011, 16:51 UTC
Message-ID: <7vvcvrxlol.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1309180056.2497.220.camel@Naugrim.eriador.com>

henri GEIST <henri.geist@flying-robots.com> writes:

Show 8 quoted lines

> We can obviously solve this by doing trees of submodules just reflecting
> the trees of dependency but it create somme problems.
>
>   1. In project 4 I have 2 times project 1 and 3 times libraries 1 and 2
>      And 2 times library 4.
>   2. It is a wast of space.
>   3. Different version of the same libraries or projects could be used.
>   4. when linking object, multiples objects will export the same symbols

All of the above are something your build procedure needs to solve regardless, even if you are not using git submodules (or even if you are not using any SCM, for that matter). If you want to (and you do want to) avoid duplication, version drift and associated issues of use of the common library 1 across project 1 and project 2, you would organize your source tree so that both of your (sub)projects to use the library code from a common location.

One possible working tree organization may look like this:

	-+- lib1
         +- project1/Makefile -- refers to ../lib1
         +- project2/Makefile -- refers to ../lib1

The top-level superproject (what you called "Anything") binds project1, project2 and lib1 as its submodules, and it can say where you want your users to fetch these submodules in its .gitmodules, and at what version lib1 (and projects) to use in its tree objects as gitlinks.

People who are _only_ interested in project1 can still clone that top-level superproject, and "submodule init" only lib1 and project1, without running "submodule init" on project2.

An interesting point your situation raises is that there is no direct way to express module dependencies in .gitmodules file right now, I think. Ideally you would want "submodule init project1" to infer automatically that project1 needs lib1 and run "submodule init lib1" for you. My gut feeling is that it belongs to .gitmodules of the superproject.