[Numpy-discussion] question about future support for python-3

Charles R Harris charlesr.harris@gmail....
Wed Sep 9 10:25:31 CDT 2009


On Wed, Sep 9, 2009 at 7:15 AM, Darren Dale <dsdale24@gmail.com> wrote:

>  On Tue, Sep 8, 2009 at 9:02 PM, David Cournapeau<cournape@gmail.com>
> wrote:
> > On Wed, Sep 9, 2009 at 9:37 AM, Darren Dale<dsdale24@gmail.com> wrote:
> >> Hi David,
> >
> >>> I already gave my own opinion on py3k, which can be summarized as:
> >>>  - it is a huge effort, and no core numpy/scipy developer has
> >>> expressed the urge to transition to py3k, since py3k does not bring
> >>> much for scientific computing.
> >>>  - very few packages with a significant portion of C have been ported
> >>> to my knowledge, hence very little experience on how to do it. AFAIK,
> >>> only small packages have been ported. Even big, pure python projects
> >>> have not been ported. The only big C project to have been ported is
> >>> python itself, and it broke compatibility and used a different source
> >>> tree than python 2.
> >>>  - it remains to be seen whether we can do the py3k support in the
> >>> same source tree as the one use for python >= 2.4. Having two source
> >>> trees would make the effort even much bigger, well over the current
> >>> developers capacity IMHO.
> >>>
> >>> The only area where I could see the PSF helping is the point 2: more
> >>> documentation, more stories about 2->3 transition.
> >>
> >> I'm surprised to hear you say that. I would think additional developer
> >> and/or financial resources would be useful, for all of the reasons you
> >> listed.
> >
> > If there was enough resources to pay someone very familiar with numpy
> > codebase for a long time, then yes, it could be useful - but I assume
> > that's out of the question. This would be very expensive as it would
> > requires several full months IMO.
> >
> > The PSF could help for the point 3, by porting other projects to py3k
> > and documenting it. The only example I know so far is pycog2
> > (
> http://mail.python.org/pipermail/python-porting/2008-December/000010.html
> ).
> >
> > Paying people to do documentation about porting C code seems like a
> > good way to spend money: it would be useful outside numpy community,
> > and would presumably be less costly.
>
> Another topic concerning documentation is API compatibility. The
> python devs have requested projects not use the 2-3 transition as an
> excuse to change their APIs, but numpy is maybe a special case. I'm
> thinking about PEP3118. Is numpy going to transition to python 3 and
> then down the road transition again to the new buffer protocol? What
> is the strategy here? My underinformed impression is that there isn't
> one, since every time PEP3118 is considered in the context of the 2-3
> transition somebody helpfully reminds the list that we aren't supposed
> to break APIs. Numpy is a critical python library, perhaps the
> transition presents an opportunity, if the community can yield a
> little on numpy's C api. For example, in the long run, what would it
> take to get numpy (or the core thereof) into the standard library, and
> can we take steps now in that direction? Would the numpy devs be
> receptive to comments from the python devs on the existing numpy
> codebase?
>
> I'm willing to pitch in and work on the transition, not because I need
> python-3 right now, but because the transition needs to happen and it
> would benefit everyone in the long run. But I would like to know that
> we are making the most of the opportunity, and have considered our
> options.
>
>
Making numpy more buffer centric is an interesting idea and might be where
we want to go with the ufuncs, but the new buffer protocol didn't go in
until python 2.6. If there was no rush I'd go with Fernando and wait until
we could be all python 2.6 all the time.

However, if anyone has the time to work on getting the c-code up to snuff
and finding out what the problems are I'm all for that. I have some notes on
the transition in the src directory and if you do anything please keep them
current.

There is a lot of work to be done in the python code also, some of which can
be done at this time, i.e., making all exceptions use class ctors, etc.

Chuck
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