python-2.6 and python-3.x

[Toshio Kuratomi]

James Antill wrote:
> On Thu, 2009-04-02 at 13:55 -0400, Tom "spot" Callaway wrote:
>> On 04/02/2009 01:46 PM, Jochen Schmitt wrote:
>>
>>> I think porting this kind of application may nned a lot of work to
>>> porting to
>>> Python 3000. So I thin wee need a python-2.6 compat package for a while
>>> until
>>> all applications will been ported.
>> The problem with this approach is that it does not motivate upstreams to
>> move to Python 3, they will just depend on the compat package, and we'll
>> have a lot of trouble convincing anyone to move.
>>
>> I think part of the solution will be for Fedora developers to help port
>> such applications to Python 3
> 
>  Personally I'm in 100% agreement with the first part of this. We
> (Fedora) shouldn't be forcing this move. Upstreams will be motivated or
> not and that will give a timeline for the move. Obviously people doing
> upstream work and Fedora work can motivate their upstream (or not) as
> they wish.
> 
>  If we get to the point where say > 75% of upstreams have moved
> (presumably in a way that their code will also work with 2.6, at least
> in the short term) then at that point I think we as a distro. should
> look at what to do with the other 25% ... either spending most of a
> release helping them, or just dropping them. Whatever.
> 
So if we take a wait for upstream path we need to make some changes in
our policy towards parallel python2/3 installs.  I think we need to
package the python3 interpreter so that people can do development of
python3 modules on Fedora.  Whether we allow python3 modules (so that
dependencies on more than the stdlib are easy) is more up in the air.
Certainly, it is going to be hard to develop very much of anything
without python3 modules but for things that are pure python, it is
possible for a developer to use easy_install to download those libraries
a lot of the time.  This does drive them away from distro packaging,
though, something I've been trying to get upstreams to see the benefit
of :-(

Note that including python3 modules opens the door for use of python3 in
applications while lack of modules pretty much means all but the
simplest command line applications will be stuck on python2.  For better
or for worse.

One thing I'm afraid of is how much trouble python3 is going to bring
for Unix.  Right now we have the opportunity to find issues and get
attention from python core devs for fixing them.  If we wait until
python-3.100 we'll be seen as johnny-come-latelys saying our platforms
are not compatible with what has already become standard practice in python.

>  Another, maybe less significant to Fedora point, is that until about
> ~F13 a non-trivial number of python developers will need to have code
> working in 2.6 _and_ 2.4. So any forced migration so that they have to
> be compatible with 2.4, 2.6 and 3.x would be a major PITA for them.
> 

About a year, year and a half?  I think that's viable but it will be
beginning to get painful.  python-2.4 and python-2.5 just aren't
compatible with python-3.x and Fedora shouldn't be staying on old
packages solely to make compatibility with python-2.4 possible.

If we want people to be able to do that, we should admit that python3
and python2.x are different languages and install both.  (potentially
doubling the number of python modules during transition).  If we want to
hold to the python3 is an upgrade of python2 path, we need to be aware
that breaking compatibility with python-2.4 is in the cards and accept
that Fedora 12 is likely to contain versions of python modules that
won't run on python-2.4/2.5

-Toshio

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