Re: Core and Not-So Core

On 5/12/05, Daniel Barkalow [off-list ref] wrote:

On Wed, 11 May 2005, Jon Seymour wrote:

quoted

The repository API would contain functionality equivalent to cat-file,
ls-tree, most of fsck-cache, rev-list, rev-tree, diff-tree, most of
the transport code - things that don't involve use of the index.

The workspace API would contain read-tree, write-tree, commit-tree,
etc - things that do involve use of the the index.

Unfortunately for this idea, you can't actually check files into or out of
the repository using the git tools without the index (in memory at least,
if not on disk). This is a bit like having a libc with all the system
calls except read and write. Sure, there are a number of programs that
would be fine that way, but it makes the API unintuitive, and most serious
programs need the extension anyway.

Daniel,

Checking in/checking out is definitely a workspace API function that
involves an index (almost certainly) an on-disk index, but reading and
writing from and to the repository is purely a repository API
function.

There is no reason why the workspace API can't make use of
"lower-level" functions in the repository API. I guess I would argue
that the repository API really shouldn't need much, if any knowledge,
of the workspace API.

The repository API knows about the on-disk structure of repository
objects - it knows how to write writing compressed, SHA1 signed
objects, it also knows how to pack and unpack the various object types
from their on-disk representation into structures manipulated by the
workspace API.

On the otherhand the workspace API knows about managing index
(workspace) state. It knows how to determine whether the
pre-conditions for a commit have been reached. It knows how to read
the workspace structures and coordinate read and writes from and to
the repository.

I really don't think this makes the API unintuitive, but then I don't
really understand why you think this is the case.

jon.
--
homepage: http://www.zeta.org.au/~jon/
blog: http://orwelliantremors.blogspot.com