Re: using bitkeeper to backport subsystems?

[Larry McVoy]

On Mon, Jul 22, 2002 at 11:29:41PM +0100, Roger Gammans wrote:
> On Mon, Jul 22, 2002 at 08:20:31AM -0700, Tom Rini wrote:
> > Possibly, once bitkeeper allowes ChangeSets to only depend on what they
> > actually need, not every previous ChangeSet in the repository.  IIRC,
> > this was one of the things Linus asked for, so hopefully it will happen.
> 
> While that would be great.
> 
> With all due respect to Larry and the bk team, I think you'll
> find determining 'needed changesets' in this case is a _hard_ problem.

Thanks, we agree completely.  It's actually an impossible problem
for a program since it requires semantic knowledge of the content
under revision control.  And even then the program can get it wrong
(think about a change which shortens the depth of the stack followed by
a change that won't work with the old stack depth, now you export that
to the other tree and it breaks yet it worked in the first tree).

> Now , bk could make this a little easier by allowing changesets to
> be exported without any dependencies (ala GNU-patch export - but
> with metadata for commit messages).

That's trivial to do, we already have a 'bk export -tpatch -r<rev>' which
does the patch part.  Combine that with 'bk changes -vr<rev>' and you have
what you are talking about on the sending side.  On the receiving side
we have 'bk import -tpatch' and 'bk comments' which do the other half.