Recording branch points (was: [MERGE/RFC] Dotted-decimal revision numbers in 'bzr log')

[David Allouche]

John Arbash Meinel wrote:
> 3) It does raise the question of whether we want 'bzr branch' to act
> just like cp -a. I know we've discussed it, and that is our current
> design. But there are some advantages if doing 'bzr branch' actually set
> a checkpoint in the branch, indicating it is a new branch, that starts a
> different line. 'pull' would reset that marker.

That would make my job much, much easier.

There is currently a model mismatch between bzr and Launchpad: the bzr
model really only knows about revisions, while Launchpad has an explicit
branch model. This disconnect makes it impossible to reliably[1]
determine whether a revision seen by Launchpad in a branch genuinely
belongs to that branch or if its part of the ancestry baggage from the
parent branch.

  [1] as usual, one can imagine heuristics based on the committer and
the branch nick, but it would be ugly and fragile.

This hurts every time Launchpad wants to automatically attach
information to a branch. For example:

  * I would like the branch page to make a distinction between "new
revisions in that branch" and "base history".
  * It can cause incorrect automatic linking of a bug to a branch.
  * It makes it difficult to determine significant information like
"Branches based on this one" and "Branches which merged this one".
  * It makes "branch heat" (something the SABDFL is very keen on having)
 impossible to define rigorously.

For the cases where the branch identity needs to be preserved, "bzr
clone" could be used. Fortunately, it is my impression that what people
normally use and advertise is "bzr branch". So although Launchpad would
still have to cope with branch cloning, it would not be the common case.

Caveat: my mind is not very clear at the moment, so maybe I am being
over-enthusiastic. Comments greatly appreciated.

-- 
                                                            -- ddaa

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 254 bytes
Desc: OpenPGP digital signature
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060909/266a833e/attachment.pgp