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Re: Why has python3 been created as a seperate language where there is still python2.7 ?

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From Stefan Behnel <stefan_ml@behnel.de>
Subject Re: Why has python3 been created as a seperate language where there is still python2.7 ?
Date Wed, 27 Jun 2012 13:22:41 +0200
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Chris Angelico, 27.06.2012 13:02:
> On Wed, Jun 27, 2012 at 8:25 PM, Christian Tismer wrote:
>> I think, for the small importance of the print statement in code, it
>> would have made the transition easier, if python 3 was as flexible
>> as python 2.7, with a symmetric
>>
>> "from __past__ import print_statement" construct.
> 
> For how long? Will Python require, in perpetuity, the code to support
> this? Must the print statement be enhanced when the print function is?
> What about bug fixes? How much dev time is required to enable backward
> compatibility past a boundary across which backward compatibility was
> not promised? And if there's a limit to the duration of this __past__
> directive, when should it be and what should happen after that point?
> 
> Much easier to simply say no.

I concur. For supporting something that shouldn't have been there in the
first place, such as a print statement in production code, it's way too
much overhead to keep it working despite of significant changes in the I/O
layer that went into Python 3.x, including the removal of the soft-space
"feature".

For comparison, the revival of the "u" string prefix in Py3.3 is a simple
change in the parser grammar that's easy to maintain but that has a huge
impact on the Py3 compatibility of code that accepts to drop support for
Py2.5 and earlier (as well as Py3.[012]) but wants to keep working in
Py2.[67] (which supports the opposite "b" prefix). We've been supporting
that in Cython for a while and it worked out really well so far.

Stefan

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Re: Why has python3 been created as a seperate language where there is still python2.7 ? Michiel Overtoom <motoom@xs4all.nl> - 2012-06-25 12:10 +0200
  Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-25 19:28 -0700
    Re: Why has python3 been created as a seperate language where there is still python2.7 ? Jeremiah Dodds <jeremiah.dodds@gmail.com> - 2012-06-26 01:04 -0400
    Re: Why has python3 been created as a seperate language where there is still python2.7 ? Stefan Behnel <stefan_ml@behnel.de> - 2012-06-26 08:24 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-27 20:32 -0700
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-27 20:32 -0700
  Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-25 19:28 -0700
    Re: Why has python3 been created as a seperate language where there is still python2.7 ? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-06-26 03:35 +0000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Terry Reedy <tjreedy@udel.edu> - 2012-06-26 00:33 -0400
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-06-26 02:15 -0400
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-06-26 07:40 +0000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Stefan Behnel <stefan_ml@behnel.de> - 2012-06-26 08:34 +0200
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-27 20:53 -0700
          Re: Why has python3 been created as a seperate language where there is still python2.7 ? alex23 <wuwei23@gmail.com> - 2012-06-27 21:05 -0700
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-27 20:53 -0700
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Christian Tismer <tismer@stackless.com> - 2012-06-27 12:25 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Chris Angelico <rosuav@gmail.com> - 2012-06-27 21:02 +1000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Stefan Behnel <stefan_ml@behnel.de> - 2012-06-27 13:22 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-06-27 07:24 -0400
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Chris Angelico <rosuav@gmail.com> - 2012-06-27 22:05 +1000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Christian Tismer <tismer@stackless.com> - 2012-06-27 15:15 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Stefan Behnel <stefan_ml@behnel.de> - 2012-06-27 15:44 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Chris Angelico <rosuav@gmail.com> - 2012-06-27 23:44 +1000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Christian Tismer <tismer@stackless.com> - 2012-06-27 16:34 +0200
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Serhiy Storchaka <storchaka@gmail.com> - 2012-06-27 21:58 +0300
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Serhiy Storchaka <storchaka@gmail.com> - 2012-06-27 22:08 +0300
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Terry Reedy <tjreedy@udel.edu> - 2012-06-27 17:14 -0400
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Christian Tismer <tismer@stackless.com> - 2012-06-28 00:11 +0200
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? alex23 <wuwei23@gmail.com> - 2012-06-27 17:44 -0700
          Re: Why has python3 been created as a seperate language where there is still python2.7 ? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-06-28 04:32 +0000
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? rantingrickjohnson@gmail.com - 2012-06-27 20:25 -0700
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Serhiy Storchaka <storchaka@gmail.com> - 2012-06-28 08:36 +0300
      Re: Why has python3 been created as a seperate language where there is still python2.7 ? Stefan Behnel <stefan_ml@behnel.de> - 2012-06-28 07:47 +0200
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? wxjmfauth@gmail.com - 2012-06-28 02:34 -0700
        Re: Why has python3 been created as a seperate language where there is still python2.7 ? wxjmfauth@gmail.com - 2012-06-28 02:34 -0700
          Re: Why has python3 been created as a seperate language where there is still python2.7 ? Chris Angelico <rosuav@gmail.com> - 2012-06-28 20:14 +1000
    Re: Why has python3 been created as a seperate language where there is still python2.7 ? Roy Smith <roy@panix.com> - 2012-06-27 07:45 -0400

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