Re: [RFC] Submodules in GIT

[Josef Weidendorfer <Josef.Weidendorfer@gmx.de>]

On Friday 01 December 2006 23:26, Linus Torvalds wrote:
> 
> On Fri, 1 Dec 2006, Josef Weidendorfer wrote:
> > > 
> > > Well, I would actually argue that you may often want to have a supermodule 
> > > and then at least have the _option_ to decide to not fetch all the 
> > > submodules.
> > 
> > If you want to allow this, you have to be able to cut off fetching the
> > objects of the supermodule at borders to given submodules, the ones you
> > do not want to track. With "border" I mean the submodule commit in some
> > tree of the supermodule.
> >
> > This looks a little bit like a shallow clone
> 
> No. 
> 
> I would say that it looks more like a "partial checkout" than a shallow 
> clone.
> 
> A shallow clone limits the data in "time" - we have _some_ data, but we 
> don't have all of the history of that data.
> 
> In contrast, a submodule that we don't fetch is an all-or-nothing 
> situation: we simply don't have the data at all, and it's really a matter 
> of simply not recursing into that submodule at all - much more like not 
> checking out a particular part of the tree.

OK.

I still think it should be about "limit in space" regarding the
objects in the local repository.

For a project containing "gcc" as submodule, and I am not
interested in this submodule, there should be a way to not need
to fetch all the objects from the gcc submodule at clone time.


What about my other argument for a submodule namespace:
You want to be able to move the relative root path of a submodule
inside of your supermodule, but yet want to have a unique name
for the submodule:
- to be able to just clone a submodule without having to know
the current position in HEAD
- more practically, e.g. to be able to name a submodule
independent from any current commit you are on in the supermodule,
e.g. to be able to store some meta information about a submodule:
- "Where is the official upstream of this submodule?"
- "Should git allow to commit rewind actions of this submodule
   in the supermodule?" (which, AFAICS, exactly has the same
   problems as publishing a rewound branch: you will get into
   merge hell when you want to pull upstream changes into the
   supermodule)
- "Should this submodule be checked out?"
and so on.