Re: [gentoo-dev] Re: Reverted python3.4 defaults

[Ben de Groot]

On 20 July 2015 at 02:31, Mike Gilbert <floppym@g.o> wrote:
> On Sun, Jul 19, 2015 at 12:42 PM, Ben de Groot <yngwin@g.o> wrote:
>> On 20 July 2015 at 00:03, Mike Gilbert <floppym@g.o> wrote:
>>> If there are no objections, I would like to enable python3.4 by
>>> default on Saturday, July 25. That means making the following change:
>>>
>>> profiles/base/make.defaults:
>>> PYTHON_TARGETS="python2_7 python3_4"
>>
>> I would like to note that we only have around 50 packages that require
>> python3, while the majority requires python2, and the remainder will
>> function with either. For this reason it seems to make more sense to
>> me to only set PYTHON_TARGETS="python2_7" as default, and leave adding
>> any python3_* targets to the user. This will also debloat our stage3
>> tarballs.
>
> It looks like we have eliminated most (all?) of the unbounded
> dependencies on dev-lang/python from the gentoo repository, so this
> could actually work to satisfy the goal of smaller stages and only
> having one version of python installed.
>
> However, it feels like a step backward to me; I would rather treat
> python3 as the primary interpreter and python2 as the one necessary
> for the legacy baggage.

I understand the sentiment, and I wish it was possible. I'm not some
kind of Luddite. But too many useful packages (still) depend on
python2. A couple of months ago I tried switching to python3 (either
3.3 or 3.4) only, but I had a growing list of stuff I wanted that
ended up in my package.use/py2 file. Pretty soon I decided it was not
worth the trouble, and I switched back to python 2.7 only.

My tree grepping shows 1527 out of 2371 packages with python support
need py2 and don't work with py3. It is definitely too early to treat
python2 as legacy.

There are two packages I want to use that need python 3 (compton and
pybugz), but I decided I can live without them. And I think this is
true for many of our users. They could happily live with just python
2.7 as only default. If they do want py3 packages, it is easy enough
to add that to PYTHON_TARGETS in make.conf, or individual useflags in
package.use.

> I don't see any strong technical reason to switch from python2 +
> python3 to python2-only enabled. Some people don't like having two
> versions of python installed -- that's about the gist of it.

Indeed, there is no strong technical reason, except that some people
like to keep their systems more lean. But I think having a smaller
stage3 tarball is a more important reason. The python team has
historically left that up to the RelEng team, which has been averse to
handling that themselves.

> So, I'm personally not going to make that change without some kind of
> vote on it. I can arrange a vote within the python team if you like.

I would like to hear from the other team members, yes.

-- 
Cheers,

Ben | yngwin
Gentoo developer