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

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

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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 include:

• 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 call
• 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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