When should Python 3.3 become the default?

[Steve Langasek]

On Fri, Oct 19, 2012 at 09:47:49AM -0400, Rodney Dawes wrote:
> On Thu, 2012-10-18 at 18:07 -0300, Roberto Alsina wrote:
> > On 10/18/2012 06:04 PM, Barry Warsaw wrote:
> > > There are good arguments on both sides, and I can probably convince myself to
> > > be either aggressive or conservative.  One of my biggest concerns against
> > > switching early is that we still have a lot of code that needs to be ported to
> > > Python 3 (any version)[3].  If fixing problems related to Python 3.3
> > > significantly detracts from the porting effort, then it might be better to
> > > wait.  Then the question becomes, wait until what?

> > On the other hand, for codebases that want to stay 2-and-3 compatible,
> > porting
> > to python 3.3 is *easier*. So maybe it's better not to wait.

> While it's somewhat easier, most people will need to support 3.2 anyway
> if they want to run their code on 12.04 at least. And the big benefit
> in that respect for 3.3 (return of u'') isn't really all that helpful
> except for very special weird cases. For people wanting to support both
> 2 and 3, it's much better to just use unicode_literals from __future__,
> and use b'' where necessary, and fix your unicode support to be correct.
> Then you get to work on pretty much all the Python 3 versions, and even
> still work on 2.6 (for people who need to support 10.04).

There are a range of different porting strategies that people might use,
depending on precisely which python versions they need to support.  However,
for anyone doing *new* work porting to python3, if we decide to go with 3.3
for raring, I don't see any reason that they should worry about 3.2 for
12.04.  If the software wasn't already using python3 in previous releases,
it doesn't make sense to (and probably isn't possible to) switch it to
python3 after the fact.  So if you're trying to support precise-raring in a
single codebase that's currently python2-only, it would be better to focus
on 2.7+3.3 and ignore 3.2 entirely.

(You're of course correct where 10.04 and 2.6 are concerned - and I have no
strong opinion about whether unicode_literals in particular are worth
skipping 3.2 for.)

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
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