[Python-Dev] PEP 405 (proposed): Python 2.8 Release Schedule

Nick Coghlan ncoghlan at gmail.com
Wed Nov 9 23:58:42 CET 2011

On Thu, Nov 10, 2011 at 7:55 AM, Barry Warsaw <barry at python.org> wrote:
>>+1 for Cardinal Biggles as release manager.

Now you need to persuade Vinay to let you trade PEP numbers with the
pyvenv PEP. Having an unrelease schedule as PEP 404 is too good an
opportunity to pass up :)

Getting boring for a moment, I suggest including the following new
section just before the copyright section:

And Now For Something Completely Different

Sorry, sorry, that's just being too silly. While the language may be
named after a British comedy troupe (and the overall tone of this PEP
reflects that), there are some serious reasons that explain why there
won't be an official 2.8 release from the CPython development team. If
a search for "Python 2.8" brought you to this document, you may not be
aware of the underlying problems in the design of Python 2.x that led
to the creation of the 3.x series.

First and foremost, Python 2.x is a language with ASCII text at its
core. The main text manipulation interfaces, the standard I/O stack
and many other elements of the standard library are built around that
assumption. While Unicode is supported, it's quite clearly an added on
feature rather than something that is fundamental to the language.
Python 3.x changes that core assumption, instead building the language
around Unicode text. This affects the builtin ``str`` type (which is
now Unicode text rather than 8-bit data), the standard I/O stack
(which now supports Unicode encoding concepts directly), what
identifier and module names are legal (with most Unicode alphanumeric
characters being supported) and several other aspects of the language.

With the text handling and associated I/O changes breaking backwards
compatibility *anyway*, Guido took the opportunity to finally
eliminate some other design defects in Python 2.x that had been
preserved solely for backwards compatibility reasons. These changes

  - complete removal of support for "classic" (i.e. pre-2.2 style)
class semantics
  - the separate ``int`` (machine level integer) and ``long``
(arbitrarily large) integer types have been merged into a single
``int`` type (that supports arbitrarily large values)
  - integer division now promotes non-integer results to binary
floating values automatically
  - the error prone ``except Exception, exc:`` syntax has been removed
(in favour of the more explicit ``except Exception as exc:``)
  - ``print`` and ``exec`` are now ordinary functions rather than statements
  - the backtick based ```x``` alternate spelling of ``repr(x)`` has
been removed
  - the ``<>`` alternate spelling of ``!=`` has been removed
  - implicit relative imports have been removed
  - star imports (i.e. ``from x import *``) are now permitted only in
module level code
  - implicit ordering comparisons between objects of different types
have been removed
  - list comprehensions no longer leak their iteration variables into
the surrounding scope
  - many APIs that previously returned lists now return iterators or
lightweight views instead (e.g. ``map`` produces an iterator,
``range`` creates a virtual sequence, ``dict.keys`` a view of the
original dict)
  - iterator advancement is now via a protocal-based builtin
(``next()`` invoking ``__next__()``) rather than an ordinary method
  - some rarely needed builtins have been relocated to standard
library modules (``reduce`` is now ``functools.reduce``, ``reload`` is
now ``imp.reload``)
  - some areas of the standard library have been rearranged in an
attempt to make the naming schemes more intuitive

More details on the backwards incompatible changes relative to the 2.x
series can be found in the `Python 3.0 What's New`_ document.

With the 3.x Unicode based architecture providing a significantly
better foundation for a language with a global audience, all new
features will appear solely in the Python 3.x series. However, as
detailed elsewhere, the 2.7 release will still be supported with bug
fixes and maintenance releases for several years.

.. _`Python 3.0 What's New`: http://docs.python.org/py3k/whatsnew/3.0.html

Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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