[rfc] bzr-colo into core

[Lluís]

Matthew D Fuller writes:

> On Wed, Mar 23, 2011 at 08:44:10AM -0400 I heard the voice of
> Gordon Tyler, and lo! it spake thus:
>>
>> So how about this: `bzr branch URL [DIR]` will create a colo repo if
>> there is no shared repo in a parent dir. If URL contains a colo
>> repo, all branches would be cloned.

> Fundamental to my conception is that

> 1) it's not a 'colo repo', it's a 'colo thing'.  Considering it as a
>    type of branch or repo messes everything up, and

> 2) you no longer create "standalone"[0] branches, you only create
>    colo- thing's.  But a colo-thing with only one branch in it is
>    functionally interchangeable with a current-day "standalone"
>    branch.

> [0] Not to be read as the current bzr term-of-art 'standalone branch'
>     for branch-with-internal-repo, just as "MetaDir1 with a branch".

I think presenting it like this is way more simple. This means branches
would be first-class citizens instead of just a different directory with
metadata.

As a side note, my feeling is that if someone posted a "colo thing" with
multiple branches, that's because they're very interrelated (e.g., a
public pipeline), so you're probably wanting to get them all.

For me, this means that being able to select a single branch inside a
colo-thing is an extremely secondary feature when performing a "branch"
operation.

What is not so secondary is that I should be able to clearly and
concisely select if I want to push my whole colo-thing (again, because
the branches are meant to be always together), or just one of its
branches (because I'm using a colo-thing just to have a single
switchable workspace).

Perhaps this could be set as "push just a branch" by default, and let
the user and plugins set it otherwise (e.g, the pipeline plugin would
set it to "push the whole colo-thing").

Summarizing, I feel the importance of branch naming in colo-things is
asymmetric, depending on whether I'm branching or pushing it.


Lluis

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