Python 3 Support: A Plan of Action

Robert Collins robertc at
Tue Sep 8 20:05:13 UTC 2015

On 9 September 2015 at 07:39, Richard Wilbur <richard.wilbur at> wrote:
> I agree, Jelmer.  Since my original plan was to release at least once
> with bug fixes and features from the trunk baseline as 2.6.x, and
> maybe once more with cleanup like Vincent's pep8 improvements
> (2.6.x++), before we branch for bzr 2.7, there will be a little time
> before we even have an opportunity to backport anything to bzr 2.6.
> Right now the question is more of whether we should backport anything
> from bzr 2.6 to 2.5 or 2.4.

FWIW here are my thoughts:

 - requiring a specific 2.7.x release like .10 is likely to cause
adoption friction
 - lots of code bases have found 2.6+ and  3.2+ to be fairly easy to
port to (if visually imposing due to no u'' support in 3.2).
 - 2.6+ and 3.3+ is pretty much a no-brainer: sure there are the odd
thing that can't be done trivially, but there's no fundamental issue
preventing single-code-base high performance code : and nothing I
recall from even the most performance sensitive gnarly bits of bzr
that would pose a problem.

So my suggestion, for what its worth, is to add a non-voting check to
PQM for some arbitrary version of Python 3.3+, and then start
iterating: there's no need IMO to remove support for any already
supported version of Python - it won't materially help the porting


Robert Collins <rbtcollins at>
Distinguished Technologist
HP Converged Cloud

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