git pull a subtree, embedded trees

[Tim Shimmin <tes@sgi.com>]

Hi,

I'm new to git and have a couple of novice questions.

* Is it possible to only pull in a subtree from
a repository.
Moreover, is it possible to have a subtree based on another
repository.
For example, have a topdir directory with subdirs,
s1, s2, s3 and s4. And then have say, s2 linked to
a repository rs2 and s3 linked to rs3, so that
one can update s2 and s3 from these other repositories but
having the rest of the tree linked from a main repository.

* Are there any tools for dumping out the contents of the
git objects in the .git/objects directory.
By dumping out, I mean an ascii representation of the data
fields for the commit and tree objects in particular.
I've written a simple small program to dump out the index
entries (cache entries).
I just want to see what is exactly stored in the .git
binary files and how they change when I do various git
operations.

Thanks a bunch.

--Tim