Switching to Python 3

[tim.lauridsen at gmail.com]

On Sat, Aug 4, 2012 at 9:46 AM, Bohuslav Kabrda <bkabrda at redhat.com> wrote:

> ----- Original Message -----
> > On Fri, Aug 03, 2012 at 03:55:26AM -0400, Bohuslav Kabrda wrote:
> > > ----- Original Message ----- (From Nick)
> > > >
> > > > I believe Fedora uses Python for more core OS infrastructure than
> > > > Ubuntu
> > > > does, so it's a bigger migration challenge. Does anaconda run on
> > > > Python
> > > > 3? Does yum?
> > > >
> > >
> > > Well, I believe they don't. But if noone pushes them, they never
> > > will. I think that a decision needs to be made when the transition
> > > will happen, so that these projects have a time frame, in which
> > > they need to adapt to Python 3.
> > >
> > I suggest that you start by asking nicely what things need to be done
> > to
> > port those things to python2 and then go to work on doing them.
> >  Trying to
> > force a change via the Feature process is reversing the order of
> > things.
> > Features don't exist to force other people to do work.  Features
> > exist to
> > showcase and coordinate the work that you are doing.
> >
>
> Ok, I probably didn't make myself clear. What I meant was making Python 3
> the default, not dropping Python 2 support. Therefore all the projects can
> still use python2 in shebangs/whatever. What I mean to achieve by this is
> saying "hey, we're switching to Python 3, it's default from now on and you
> should start porting your code and stop writing python3-incompatible code"
> - and I will be very glad to help them.
>
> > For the package management stack, I know that one big blocker is that
> > pycurl
> > doesn't have a python3 port.  There's a patch out there to add it
> > (complete
> > with reference counting leaks and other bugs :-(  but pycurl upstream
> > seems
> > dead.  So one of the very first steps would be for someone to take
> > over
> > pycurl upstream maintainance and add python3 support.  (And then
> > start
> > fixing reference leaks and other bugs in both the python2 and python3
> > bindings).
> >
> > > > It's that delta of Python applications that Fedora ships as
> > > > required
> > > > components in the base OS, but Ubuntu does not, that will
> > > > potentially
> > > > cause problems.
> > > >
> > >
> > > Sure, it will cause problems. But it will cause them eventually.
> > > Fedora 19 may be too soon (personally I think it's not), but we
> > > should really start pushing the various projects to actually start
> > > doing something about Python 3.
> > >
> > The best way to push is to work with projects to port their code.  I
> > think
> > talking to the projects that require python2 that are in the LiveCDs
> > and the
> > install DVDs and porting the libraries that they require to be
> > buildable as
> > both python2 and python3 modules would be a sensible first step.
> >  Then work
> > on porting the applications themselves.  Along the way, you can
> > figure out
> > some important milestones to call out in Features.  "The 100 python3
> > library
> > port challenge -- Fedora Contributors helped port 100 python
> > libraries to
> > python3",  "50% python3 in distro -- half of all python modules that
> > are
> > packaged are now python3 capable", "python3 package management stack
> > -- our
> > package manager is now running on python3 instead of python2"
> >
> > One thing to watch out for is that once you start porting
> > applications, the
> > live images and install dvds will start requiring python3.  If you
> > aren't
> > careful, some releases may end up requiring both python2 and python3.
> >  This
> > is something that would need to be coordinated with the spins as well
> > as the
> > applications you're porting to figure out what is okay as a size
> > constraint.
> > You may end up having to maintain a parallel python3 branch for many
> > applications until all of the applications on an image are ported to
> > python3.
> >
> > -Toshio
> >
> > _______________________________________________
> > python-devel mailing list
> > python-devel at lists.fedoraproject.org
> > https://admin.fedoraproject.org/mailman/listinfo/python-devel
>
> --
> Regards,
> Bohuslav "Slavek" Kabrda.
> _______________________________________________
> python-devel mailing list
> python-devel at lists.fedoraproject.org
> https://admin.fedoraproject.org/mailman/listinfo/python-devel
>

I think you miss the point, you just don't change the default
/usr/bin/python to python 3 and forces 90% of the python apps in Fedora to
change there shebangs to /ust/bin/python2
that is not the way to do it, when 90% of the python apps in Fedora is
python3 then we can start to talk about.
The transition to python3 starts upstream of the python apps and before the
big majority running python3, changing default python is nonsense. IMO

Tim
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