When should Python 3.3 become the default?

[Dmitrijs Ledkovs]

On 18 October 2012 22:04, Barry Warsaw <barry at ubuntu.com> wrote:
> Since we're all raring to go now, this seems like a good time to ask for
> feedback on some Python 3 decisions for 13.04.  Yes, we have a UDS-R session
> on this[1] but I expect the archive will open before UDS, so it would be
> better to have some direction earlier if possible.  I've chatted briefly with
> Matthias and Scott K, but I don't want to accidentally misrepresent their
> opinions.  Instead, I'll express my own and let them follow up.  Please let us
> know what you think.
>
> Some quick background: Python 3.2 is the default in 12.10.  Python 3.3 is
> available but it is not a supported version, which effectively means that
> pure-Python packages installed for 3.2 should be importable[2] in 3.3, but no
> extension modules are built.  So for example, `import gi.repository` will fail
> in 3.3 on 12.10.
>
> Continuing on discussions we've had at previous UDSes, and looking ahead to
> the probably schedule for Python 3.4, it is almost certain that we'll carry
> Python 3.3 as the default Python 3 for the next LTS (14.04).  Whether we'll
> also have Python 3.2 or 3.4 in 14.04 LTS is an open question we don't need to
> decide right now.
>
> Clearly we're going to enable Python 3.3 as a supported Python 3 version when
> the 'raring' archive opens up.  The question is whether 3.3 should be the
> default Python 3 as soon as the archive opens, or whether we should keep 3.2
> as the default, enable 3.3, and watch for any fallout before making the switch
> later in the 13.04 cycle.
>
> 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?
>
> I am slightly leaning toward switching early, so that we can begin to take
> advantage of some of features[4] of Python 3.3 that will benefit Ubuntu (and
> Debian of course).  Two big ones are PEP 420 (namespace packages) and PEP 393
> (flexible string representations).  Others that could prove quite useful
> include: PEP 414 (reinstatement of explicit Unicode literals), PEP 405
> (built-in virtual environments), PEP 417 (mock in the standard library), and
> PEP 3151 (Reworking the OS and IO exceptions).
>
> What do you think?
>

Open up with 3.3 as the default python3. If you throw the
python3-defaults in a ppa.

Security team would not be thrilled to support more than one of each
python series, therefore the aim would be to get 3.2 out of the
archive or at least out of main.

Than means that python3-defaults should be uploaded while raring is
not opened and before the auto-syncs come in.

If you recall quantal opening:

https://lists.ubuntu.com/archives/ubuntu-devel-announce/2012-April/000955.html

We had gcc-4.7 transition, boost1.50 transition, OpenJDK 7 transition.

The http://bugs.debian.org/cgi-bin/pkgreport.cgi?users=debian-python@lists.debian.org;tag=python3.3
does not look that scary at all.

There are a lot of packages involved, but this archive opening will be
relatively quiet compared to transitions we managed at quantal
opening.

Regards,

Dmitrijs.