looms: compatibility, performance, alternatives?

[Jonathan Lange]

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On Fri, Jan 9, 2009 at 6:39 AM, David Reitter  wrote:
> For the past 4 years or so, I've been working on a  project that sits
> downstream for a bigger one.   I'm considering moving my project to Bazaar
> (from CVS), as will the upstream project.  I would like my changes to be
> organized so that they can easily be propagated upstream.   Thus, I'd like
> to track several threads of development (patchsets) in order to be able to
> push upstream (or see pulled) some of the changes.  For example, our stack
> of patches may look like this (in reality we have some 30 separate patches):
>
> 1 - proj-specific / downstream
> 2 - patch-C
> 3 - patch-B
> 4 - patch-A
> 5 - upstream
>
> I understand that the bzr-loom plugin is the right thing to use.  I have a
> few beginner's questions:
>

I'm not a loom expert, I just use it a lot. My answers here might be
corrected later by others more knowledgable.

> - Suppose a fellow developer does not have the bzr-loom plugin installed.
>  When they get the branch, do they get all patches by default? Which thread
> are their commits assigned to?  Can I configure this?  I would want them to
> commit to the top thread (downstream, level 1).
>

No they don't. They wouldn't be able to commit directly to the loom at all.

> - Does using the bzr-loom plugin have negative performance consequences,
> particularly on common operations such as branching/checking out,
> committing, pushing, merging, and "bzr log"?
>

Not that I've noticed.

> - Suppose the upstream project does not use bzr-looms: I presume I can still
> merge from it and push single threads to it without problems.  Correct?
>

You can export each thread of a loom into its own branch using the
'bzr export-loom' command. From there, you can merge and push it to
upstream.

> - What are the alternatives to using loom?

Lots of branches, carefully managed :)

There might be others.

>  Note that it is a requirement for us to be able to provide simple access to
> the complete project code, that is, at level 1.
>

Then you might want some hook that exports the thread as a separate
branch on commit. Maybe.

Hope this helps,
jml
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