The real problem with Python 3 - no business case for conversion (was "I strongly dislike Python 3")

[MRAB]

geremy condra wrote:
> On Wed, Jul 7, 2010 at 8:26 PM, Brendan Abel <007brendan at gmail.com> wrote:
>> On Jul 7, 3:00 pm, MRAB <pyt... at mrabarnett.plus.com> wrote:
>>> Brendan Abel wrote:
>>>>>>> One thing that would be very useful is how to maintain something that
>>>>>>> works on 2.x and 3.x, but not limiting yourself to 2.6. Giving up
>>>>>>> versions below 2.6 is out of the question for most projects with a
>>>>>>> significant userbase IMHO. As such, the idea of running the python 3
>>>>>>> warnings is not so useful IMHO - unless it could be made to work
>>>>>>> better for python 2.x < 2.6, but I am not sure the idea even makes
>>>>>>> sense.
>>>> The entire fact that 3.x was *designed* to be incompatible should tell
>>>> you that supporting 2.x and 3.x with a single code base is a bad idea,
>>>> except for the very smallest of projects.  This is the point where a
>>>> project should fork and provide two different versions.
>>> I wouldn't say that 3.x was designed to be incompatible. It was designed
>>> to tidy the language, and the incompatibilities are an unfortunate
>>> result.
>> You're missing the point, and arguing semantics.  It's a good thing I
>> didn't misspell anything.
>>
>> Python 3.x will continue to change.  The incompatibilities between 3.x
>> and 2.x will only become more numerous.  If your goal is to support
>> 2.x, and 3.x, you'd be best supporting them separately.
> 
> I maintain two projects that have to work from 2.5 to 3.1. On one of
> them (~5kloc) we took the separate support route, and on the other
> (~30kloc) I decided to keep a single codebase. IME the maintenance
> burden on the former is substantially higher than the latter. Is the
> difference in difficulty perhaps domain-related, or a result of a
> certain style of coding? Could you give us some more details about
> what you were working on that caused you to conclude this?
> 
In my work on the regex module I use a single codebase and generate the
sources for Python 2.5-2.7 and for Python 3.1 from it. It works easily
enough for me.