[Numpy-discussion] [review] py3k_bootstrap branch

[David Cournapeau]

On Wed, May 6, 2009 at 12:26 AM, Bruce Southey <bsouthey at gmail.com> wrote:
> David Cournapeau wrote:
>> Hi,
>>
>> I spent some more time on making numpy.distutils runnable under python
>> 3. I finally made up to the point where it breaks at C code
>> compilation, so we can start working on the hard part. The branch is
>> there for review
>>
>> http://github.com/cournape/numpy/commits/py3k_bootstrap
>>
>> The code is quite ugly to be honest, but I have not found a better
>> way; suggestions are welcomed. The biggest pain is by far exception
>> catching (you can't do except IOError, e in python 3), and then print.
>> Most other things can be handled by careful application of 2to3 with
>> the fixers which keep python2 compatibility (print is unfortunately
>> not one of them). There are also a few python 3.* bugs in distutils (I
>> guess few C-based extensions made it for python 3 already).
>>
>> The rationale for making numpy.distutils runnable under both python2
>> and python3 (instead of just applying 2to3 on it):
>>  - it enables us to bootstrap our build process through the distutils
>> 2to3 command (which is supposed to convert code to python 3 from
>> python 2 sources on the fly).
>>  - The few informations I found on non trivial port all made sure
>> their setup.py was python 2 and 3 compatible - which means
>> numpy.distutils for us.
>>  - 2to3 is very slow (takes 5 minutes for me on numpy), so having to
>> apply it every time from pristine source for python 3 support would be
>> very painful IMHO.
>>
>> cheers,
>>
>> David
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>>
> Hi,
> This is really impressive!
>
> I agree that there should only be one source for Python 2 and Python 3.
> Although it does mean that any new code must be compatible with both
> Python 2.4+ and Python 3.+.

That's almost impossible. It would be extremely painful to be source
compatible. But we should aim at being able to produce most python 3
code from 2to3.

>
> I have only been browsing some of the code and was wondering about the
> usage of print. In many cases it seems that the print statements are
> perhaps warnings. If so, should the print statements be changed to warnings?

yes, there are many things which could be done better. Ideally, we
should first clean up numpy.distutils code, but that's not a very
exciting task :) The goal is more reach something which works as
quickly as possible, so that we can focus on the real issues (C code
and design decision for strings vs bytes, etc...).

David