Re: VCS comparison table

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Linus Torvalds wrote:

On Tue, 17 Oct 2006, Aaron Bentley wrote:

quoted

quoted

Excuse me? What does that "throws away your local commit ordering" mean?

Say this is the ordering in branch A:

a
|
b
|
c

Say this is the ordering in branch B:

a
|
b
|\
d c
|/
e

When A pulls B, it gets the same ordering as B has.  If B did not have e
and c, the pull would fail.

Sure. But that doesn't throw away any local commit ordering. The original 
order (a->b->c) is still very much there.

After the pull, it's no longer the mainline ordering for the branch.  c
is represented a revision that was merged into the branch, while d is
represented as a commit on the mainline of the branch.

The fact that there was a branch 
off 'b' and there is also (a->b->d) and a merge of the two at 'e' doesn't 
take away anything from the original local commit ordering.

It means the the order that revisions are shown in log commands changes,
and the revision numbers can change.

But that's a totally specious "record". It has no meaning in a distributed 
SCM. There is absolutely zero semantic information in it.

It records the committer, the date, the commit message, the parent
revisions.

The fact that you _locally_ want to remember where you were is a total 
non-issue for a true distributed system. You shouldn't force everybody 
else to see your local view - since it has no relevance to them, and 
doesn't add any information.

Nobody is forced to use your local view.

In other words, the empty merge is totally semantically empty even in the 
bazaar world. Why does it exist?

It exists because it is useful.  Because it makes the behavior of bzr
merge uniform.  Because in some workflows, commits show that a person
has signed off on a change.

It's not something special-- it's just another commit, like regular
commits, and merge commits.  It would be harder to forbid than it is to
permit.

Aaron
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.2 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFFNXQQ0F+nu1YWqI0RAnxDAJ4hbuLkEK1eBlyoEOz7NAlqLVth9gCfed4w
nfeiR2KVvN+N9zdSrC8MKcY=
=et73
-----END PGP SIGNATURE-----