690 lines
28 KiB
ReStructuredText
690 lines
28 KiB
ReStructuredText
****************************
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What's New in Python 2.7
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****************************
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:Author: A.M. Kuchling (amk at amk.ca)
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:Release: |release|
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:Date: |today|
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.. Fix accents on Kristjan Valur Jonsson, Fuerstenau, Tarek Ziade.
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.. $Id$
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Rules for maintenance:
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* Anyone can add text to this document. Do not spend very much time
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on the wording of your changes, because your text will probably
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get rewritten to some degree.
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* The maintainer will go through Misc/NEWS periodically and add
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changes; it's therefore more important to add your changes to
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Misc/NEWS than to this file.
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* This is not a complete list of every single change; completeness
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is the purpose of Misc/NEWS. Some changes I consider too small
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or esoteric to include. If such a change is added to the text,
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I'll just remove it. (This is another reason you shouldn't spend
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too much time on writing your addition.)
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* If you want to draw your new text to the attention of the
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maintainer, add 'XXX' to the beginning of the paragraph or
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section.
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* It's OK to just add a fragmentary note about a change. For
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example: "XXX Describe the transmogrify() function added to the
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socket module." The maintainer will research the change and
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write the necessary text.
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* You can comment out your additions if you like, but it's not
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necessary (especially when a final release is some months away).
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* Credit the author of a patch or bugfix. Just the name is
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sufficient; the e-mail address isn't necessary.
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* It's helpful to add the bug/patch number in a parenthetical comment.
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XXX Describe the transmogrify() function added to the socket
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module.
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(Contributed by P.Y. Developer; :issue:`12345`.)
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This saves the maintainer some effort going through the SVN logs
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when researching a change.
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This article explains the new features in Python 2.7.
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No release schedule has been decided yet for 2.7.
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.. Compare with previous release in 2 - 3 sentences here.
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add hyperlink when the documentation becomes available online.
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Python 3.1
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================
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Much as Python 2.6 incorporated features from Python 3.0,
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version 2.7 is influenced by features from 3.1.
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XXX mention importlib; anything else?
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One porting change: the :option:`-3` switch now automatically
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enables the :option:`-Qwarn` switch that causes warnings
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about using classic division with integers and long integers.
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.. ========================================================================
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.. Large, PEP-level features and changes should be described here.
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.. ========================================================================
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PEP 372: Adding an ordered dictionary to collections
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====================================================
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XXX write this
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Several modules will now use :class:`OrderedDict` by default. The
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:mod:`ConfigParser` module uses :class:`OrderedDict` for the list
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of sections and the options within a section.
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The :meth:`namedtuple._asdict` method returns an :class:`OrderedDict`
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as well.
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Other Language Changes
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======================
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Some smaller changes made to the core Python language are:
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* :meth:`str.format` method now supports automatic numbering of the replacement
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fields. This makes using :meth:`str.format` more closely resemble using
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``%s`` formatting::
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>>> '{}:{}:{}'.format(2009, 04, 'Sunday')
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'2009:4:Sunday'
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>>> '{}:{}:{day}'.format(2009, 4, day='Sunday')
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'2009:4:Sunday'
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The auto-numbering takes the fields from left to right, so the first ``{...}``
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specifier will use the first argument to :meth:`str.format`, the next
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specifier will use the next argument, and so on. You can't mix auto-numbering
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and explicit numbering -- either number all of your specifier fields or none
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of them -- but you can mix auto-numbering and named fields, as in the second
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example above. (Contributed by Eric Smith; :issue`5237`.)
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* The :func:`int` and :func:`long` types gained a ``bit_length``
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method that returns the number of bits necessary to represent
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its argument in binary::
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>>> n = 37
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>>> bin(37)
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'0b100101'
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>>> n.bit_length()
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6
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>>> n = 2**123-1
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>>> n.bit_length()
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123
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>>> (n+1).bit_length()
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124
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(Contributed by Fredrik Johansson and Victor Stinner; :issue:`3439`.)
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* Conversions from long integers and regular integers to floating
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point now round differently, returning the floating-point number
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closest to the number. This doesn't matter for small integers that
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can be converted exactly, but for large numbers that will
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unavoidably lose precision, Python 2.7 will now approximate more
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closely. For example, Python 2.6 computed the following::
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>>> n = 295147905179352891391
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>>> float(n)
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2.9514790517935283e+20
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>>> n - long(float(n))
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65535L
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Python 2.7's floating-point result is larger, but much closer to the
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true value::
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>>> n = 295147905179352891391
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>>> float(n)
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2.9514790517935289e+20
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>>> n-long(float(n)
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... )
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-1L
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(Implemented by Mark Dickinson; :issue:`3166`.)
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* The :class:`bytearray` type's :meth:`translate` method will
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now accept ``None`` as its first argument. (Fixed by Georg Brandl;
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:issue:`4759`.)
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.. ======================================================================
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Optimizations
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-------------
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Several performance enhancements have been added:
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.. * A new :program:`configure` option, :option:`--with-computed-gotos`,
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compiles the main bytecode interpreter loop using a new dispatch
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mechanism that gives speedups of up to 20%, depending on the system
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and benchmark. The new mechanism is only supported on certain
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compilers, such as gcc, SunPro, and icc.
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* The garbage collector now performs better when many objects are
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being allocated without deallocating any. A full garbage collection
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pass is only performed when the middle generation has been collected
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10 times and when the number of survivor objects from the middle
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generation exceeds 10% of the number of objects in the oldest
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generation. The second condition was added to reduce the number
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of full garbage collections as the number of objects on the heap grows,
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avoiding quadratic performance when allocating very many objects.
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(Suggested by Martin von Loewis and implemented by Antoine Pitrou;
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:issue:`4074`.)
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* The garbage collector tries to avoid tracking simple containers
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which can't be part of a cycle. In Python 2.7, this is now true for
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tuples and dicts containing atomic types (such as ints, strings,
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etc.). Transitively, a dict containing tuples of atomic types won't
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be tracked either. This helps reduce the cost of each
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garbage collection by decreasing the number of objects to be
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considered and traversed by the collector.
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(Contributed by Antoine Pitrou; :issue:`4688`.)
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* Integers are now stored internally either in base 2**15 or in base
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2**30, the base being determined at build time. Previously, they
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were always stored in base 2**15. Using base 2**30 gives
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significant performance improvements on 64-bit machines, but
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benchmark results on 32-bit machines have been mixed. Therefore,
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the default is to use base 2**30 on 64-bit machines and base 2**15
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on 32-bit machines; on Unix, there's a new configure option
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:option:`--enable-big-digits` that can be used to override this default.
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Apart from the performance improvements this change should be
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invisible to end users, with one exception: for testing and
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debugging purposes there's a new structseq ``sys.long_info`` that
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provides information about the internal format, giving the number of
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bits per digit and the size in bytes of the C type used to store
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each digit::
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>>> import sys
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>>> sys.long_info
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sys.long_info(bits_per_digit=30, sizeof_digit=4)
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(Contributed by Mark Dickinson; :issue:`4258`.)
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Another set of changes made long objects a few bytes smaller: 2 bytes
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smaller on 32-bit systems and 6 bytes on 64-bit.
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(Contributed by Mark Dickinson; :issue:`5260`.)
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* The division algorithm for long integers has been made faster
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by tightening the inner loop, doing shifts instead of multiplications,
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and fixing an unnecessary extra iteration.
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Various benchmarks show speedups of between 50% and 150% for long
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integer divisions and modulo operations.
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(Contributed by Mark Dickinson; :issue:`5512`.)
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* The implementation of ``%`` checks for the left-side operand being
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a Python string and special-cases it; this results in a 1-3%
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performance increase for applications that frequently use ``%``
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with strings, such as templating libraries.
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(Implemented by Collin Winter; :issue:`5176`.)
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* List comprehensions with an ``if`` condition are compiled into
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faster bytecode. (Patch by Antoine Pitrou, back-ported to 2.7
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by Jeffrey Yasskin; :issue:`4715`.)
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.. ======================================================================
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New, Improved, and Deprecated Modules
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=====================================
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As in every release, Python's standard library received a number of
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enhancements and bug fixes. Here's a partial list of the most notable
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changes, sorted alphabetically by module name. Consult the
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:file:`Misc/NEWS` file in the source tree for a more complete list of
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changes, or look through the Subversion logs for all the details.
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* The :mod:`bz2` module's :class:`BZ2File` now supports the context
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management protocol, so you can write ``with bz2.BZ2File(...) as f: ...``.
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(Contributed by Hagen Fuerstenau; :issue:`3860`.)
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* New class: the :class:`Counter` class in the :mod:`collections` module is
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useful for tallying data. :class:`Counter` instances behave mostly
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like dictionaries but return zero for missing keys instead of
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raising a :exc:`KeyError`:
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.. doctest::
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:options: +NORMALIZE_WHITESPACE
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>>> from collections import Counter
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>>> c = Counter()
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>>> for letter in 'here is a sample of english text':
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... c[letter] += 1
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...
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>>> c
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Counter({' ': 6, 'e': 5, 's': 3, 'a': 2, 'i': 2, 'h': 2,
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'l': 2, 't': 2, 'g': 1, 'f': 1, 'm': 1, 'o': 1, 'n': 1,
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'p': 1, 'r': 1, 'x': 1})
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>>> c['e']
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5
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>>> c['z']
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0
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There are two additional :class:`Counter` methods: :meth:`most_common`
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returns the N most common elements and their counts, and :meth:`elements`
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returns an iterator over the contained element, repeating each element
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as many times as its count::
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>>> c.most_common(5)
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[(' ', 6), ('e', 5), ('s', 3), ('a', 2), ('i', 2)]
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>>> c.elements() ->
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'a', 'a', ' ', ' ', ' ', ' ', ' ', ' ',
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'e', 'e', 'e', 'e', 'e', 'g', 'f', 'i', 'i',
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'h', 'h', 'm', 'l', 'l', 'o', 'n', 'p', 's',
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's', 's', 'r', 't', 't', 'x'
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Contributed by Raymond Hettinger; :issue:`1696199`.
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The :class:`namedtuple` class now has an optional *rename* parameter.
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If *rename* is true, field names that are invalid because they've
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been repeated or that aren't legal Python identifiers will be
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renamed to legal names that are derived from the field's
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position within the list of fields:
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>>> from collections import namedtuple
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>>> T = namedtuple('T', ['field1', '$illegal', 'for', 'field2'], rename=True)
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>>> T._fields
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('field1', '_1', '_2', 'field2')
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(Added by Raymond Hettinger; :issue:`1818`.)
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The :class:`deque` data type now exposes its maximum length as the
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read-only :attr:`maxlen` attribute. (Added by Raymond Hettinger.)
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* In Distutils, :func:`distutils.sdist.add_defaults` now uses
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*package_dir* and *data_files* to create the MANIFEST file.
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:mod:`distutils.sysconfig` will now read the :envvar:`AR`
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environment variable.
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It is no longer mandatory to store clear-text passwords in the
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:file:`.pypirc` file when registering and uploading packages to PyPI. As long
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as the username is present in that file, the :mod:`distutils` package will
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prompt for the password if not present. (Added by Tarek Ziade,
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based on an initial contribution by Nathan Van Gheem; :issue:`4394`.)
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A Distutils setup can now specify that a C extension is optional by
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setting the *optional* option setting to true. If this optional is
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supplied, failure to build the extension will not abort the build
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process, but instead simply not install the failing extension.
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(Contributed by Georg Brandl; :issue:`5583`.)
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* New method: the :class:`Decimal` class gained a
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:meth:`from_float` class method that performs an exact conversion
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of a floating-point number to a :class:`Decimal`.
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Note that this is an **exact** conversion that strives for the
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closest decimal approximation to the floating-point representation's value;
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the resulting decimal value will therefore still include the inaccuracy,
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if any.
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For example, ``Decimal.from_float(0.1)`` returns
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``Decimal('0.1000000000000000055511151231257827021181583404541015625')``.
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(Implemented by Raymond Hettinger; :issue:`4796`.)
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* The :class:`Fraction` class will now accept two rational numbers
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as arguments to its constructor.
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(Implemented by Mark Dickinson; :issue:`5812`.)
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* New function: the :mod:`gc` module's :func:`is_tracked` returns
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true if a given instance is tracked by the garbage collector, false
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otherwise. (Contributed by Antoine Pitrou; :issue:`4688`.)
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* The :mod:`gzip` module's :class:`GzipFile` now supports the context
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management protocol, so you can write ``with gzip.GzipFile(...) as f: ...``.
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(Contributed by Hagen Fuerstenau; :issue:`3860`.)
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It's now possible to override the modification time
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recorded in a gzipped file by providing an optional timestamp to
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the constructor. (Contributed by Jacques Frechet; :issue:`4272`.)
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* The :class:`io.FileIO` class now raises an :exc:`OSError` when passed
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an invalid file descriptor. (Implemented by Benjamin Peterson;
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:issue:`4991`.)
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* New function: ``itertools.compress(*data*, *selectors*)`` takes two
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iterators. Elements of *data* are returned if the corresponding
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value in *selectors* is true::
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itertools.compress('ABCDEF', [1,0,1,0,1,1]) =>
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A, C, E, F
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New function: ``itertools.combinations_with_replacement(*iter*, *r*)``
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returns all the possible *r*-length combinations of elements from the
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iterable *iter*. Unlike :func:`combinations`, individual elements
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can be repeated in the generated combinations::
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itertools.combinations_with_replacement('abc', 2) =>
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('a', 'a'), ('a', 'b'), ('a', 'c'),
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('b', 'b'), ('b', 'c'), ('c', 'c')
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Note that elements are treated as unique depending on their position
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in the input, not their actual values.
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The :class:`itertools.count` function now has a *step* argument that
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allows incrementing by values other than 1. :func:`count` also
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now allows keyword arguments, and using non-integer values such as
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floats or :class:`Decimal` instances. (Implemented by Raymond
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Hettinger; :issue:`5032`.)
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:func:`itertools.combinations` and :func:`itertools.product` were
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previously raising :exc:`ValueError` for values of *r* larger than
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the input iterable. This was deemed a specification error, so they
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now return an empty iterator. (Fixed by Raymond Hettinger; :issue:`4816`.)
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* The :mod:`json` module was upgraded to version 2.0.9 of the
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simplejson package, which includes a C extension that makes
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encoding and decoding faster.
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(Contributed by Bob Ippolito; :issue:`4136`.)
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To support the new :class:`OrderedDict` type, :func:`json.load`
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now has an optional *object_pairs_hook* parameter that will be called
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with any object literal that decodes to a list of pairs.
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(Contributed by Raymond Hettinger; :issue:`5381`.)
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* The :mod:`multiprocessing` module's :class:`Manager*` classes
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can now be passed a callable that will be called whenever
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a subprocess is started, along with a set of arguments that will be
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passed to the callable.
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(Contributed by lekma; :issue:`5585`.)
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* The :mod:`pydoc` module now has help for the various symbols that Python
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uses. You can now do ``help('<<')`` or ``help('@')``, for example.
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(Contributed by David Laban; :issue:`4739`.)
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* The :mod:`re` module's :func:`split`, :func:`sub`, and :func:`subn`
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now accept an optional *flags* argument, for consistency with the
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other functions in the module. (Added by Gregory P. Smith.)
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* New function: the :mod:`subprocess` module's
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:func:`check_output` runs a command with a specified set of arguments
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and returns the command's output as a string when the command runs without
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error, or raises a :exc:`CalledProcessError` exception otherwise.
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::
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>>> subprocess.check_output(['df', '-h', '.'])
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'Filesystem Size Used Avail Capacity Mounted on\n
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/dev/disk0s2 52G 49G 3.0G 94% /\n'
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>>> subprocess.check_output(['df', '-h', '/bogus'])
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...
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subprocess.CalledProcessError: Command '['df', '-h', '/bogus']' returned non-zero exit status 1
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(Contributed by Gregory P. Smith.)
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* New function: :func:`is_declared_global` in the :mod:`symtable` module
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returns true for variables that are explicitly declared to be global,
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false for ones that are implicitly global.
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(Contributed by Jeremy Hylton.)
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* The ``sys.version_info`` value is now a named tuple, with attributes
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named ``major``, ``minor``, ``micro``, ``releaselevel``, and ``serial``.
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(Contributed by Ross Light; :issue:`4285`.)
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* The :mod:`threading` module's :meth:`Event.wait` method now returns
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the internal flag on exit. This means the method will usually
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return true because :meth:`wait` is supposed to block until the
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internal flag becomes true. The return value will only be false if
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a timeout was provided and the operation timed out.
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(Contributed by XXX; :issue:`1674032`.)
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* The :mod:`unittest` module was enhanced in several ways.
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The progress messages will now show 'x' for expected failures
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and 'u' for unexpected successes when run in verbose mode.
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(Contributed by Benjamin Peterson.)
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Test cases can raise the :exc:`SkipTest` exception to skip a test.
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(:issue:`1034053`.)
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The error messages for :meth:`assertEqual`,
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:meth:`assertTrue`, and :meth:`assertFalse`
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failures now provide more information. If you set the
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:attr:`longMessage` attribute of your :class:`TestCase` classes to
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true, both the standard error message and any additional message you
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provide will be printed for failures. (Added by Michael Foord; :issue:`5663`.)
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The :meth:`assertRaises` and :meth:`failUnlessRaises` methods now
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return a context handler when called without providing a callable
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object to run. For example, you can write this::
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with self.assertRaises(KeyError):
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raise ValueError
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(Implemented by Antoine Pitrou; :issue:`4444`.)
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The methods :meth:`addCleanup` and :meth:`doCleanups` were added.
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:meth:`addCleanup` allows you to add cleanup functions that
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will be called unconditionally (after :meth:`setUp` if
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:meth:`setUp` fails, otherwise after :meth:`tearDown`). This allows
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for much simpler resource allocation and deallocation during tests.
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:issue:`5679`
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A number of new methods were added that provide more specialized
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tests. Many of these methods were written by Google engineers
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for use in their test suites; Gregory P. Smith, Michael Foord, and
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GvR worked on merging them into Python's version of :mod:`unittest`.
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* :meth:`assertIsNone` and :meth:`assertIsNotNone` take one
|
|
expression and verify that the result is or is not ``None``.
|
|
|
|
* :meth:`assertIs` and :meth:`assertIsNot` take two values and check
|
|
whether the two values evaluate to the same object or not.
|
|
(Added by Michael Foord; :issue:`2578`.)
|
|
|
|
* :meth:`assertGreater`, :meth:`assertGreaterEqual`,
|
|
:meth:`assertLess`, and :meth:`assertLessEqual` compare
|
|
two quantities.
|
|
|
|
* :meth:`assertMultiLineEqual` compares two strings, and if they're
|
|
not equal, displays a helpful comparison that highlights the
|
|
differences in the two strings.
|
|
|
|
* :meth:`assertRegexpMatches` checks whether its first argument is a
|
|
string matching a regular expression provided as its second argument.
|
|
|
|
* :meth:`assertRaisesRegexp` checks whether a particular exception
|
|
is raised, and then also checks that the string representation of
|
|
the exception matches the provided regular expression.
|
|
|
|
* :meth:`assertIn` and :meth:`assertNotIn` tests whether
|
|
*first* is or is not in *second*.
|
|
|
|
* :meth:`assertSameElements` tests whether two provided sequences
|
|
contain the same elements.
|
|
|
|
* :meth:`assertSetEqual` compares whether two sets are equal, and
|
|
only reports the differences between the sets in case of error.
|
|
|
|
* Similarly, :meth:`assertListEqual` and :meth:`assertTupleEqual`
|
|
compare the specified types and explain the differences.
|
|
More generally, :meth:`assertSequenceEqual` compares two sequences
|
|
and can optionally check whether both sequences are of a
|
|
particular type.
|
|
|
|
* :meth:`assertDictEqual` compares two dictionaries and reports the
|
|
differences. :meth:`assertDictContainsSubset` checks whether
|
|
all of the key/value pairs in *first* are found in *second*.
|
|
|
|
* A new hook, :meth:`addTypeEqualityFunc` takes a type object and a
|
|
function. The :meth:`assertEqual` method will use the function
|
|
when both of the objects being compared are of the specified type.
|
|
This function should compare the two objects and raise an
|
|
exception if they don't match; it's a good idea for the function
|
|
to provide additional information about why the two objects are
|
|
matching, much as the new sequence comparison methods do.
|
|
|
|
:func:`unittest.main` now takes an optional ``exit`` argument.
|
|
If False ``main`` doesn't call :func:`sys.exit` allowing it to
|
|
be used from the interactive interpreter. :issue:`3379`.
|
|
|
|
:class:`TestResult` has new :meth:`startTestRun` and
|
|
:meth:`stopTestRun` methods; called immediately before
|
|
and after a test run. :issue:`5728` by Robert Collins.
|
|
|
|
* The :func:`is_zipfile` function in the :mod:`zipfile` module will now
|
|
accept a file object, in addition to the path names accepted in earlier
|
|
versions. (Contributed by Gabriel Genellina; :issue:`4756`.)
|
|
|
|
:mod:`zipfile` now supports archiving empty directories and
|
|
extracts them correctly. (Fixed by Kuba Wieczorek; :issue:`4710`.)
|
|
|
|
.. ======================================================================
|
|
.. whole new modules get described in subsections here
|
|
|
|
importlib: Importing Modules
|
|
------------------------------
|
|
|
|
Python 3.1 includes the :mod:`importlib` package, a re-implementation
|
|
of the logic underlying Python's :keyword:`import` statement.
|
|
:mod:`importlib` is useful for implementors of Python interpreters and
|
|
to user who wish to write new importers that can participate in the
|
|
import process. Python 2.7 doesn't contain the complete
|
|
:mod:`importlib` package, but instead has a tiny subset that contains
|
|
a single function, :func:`import_module`.
|
|
|
|
``import_module(*name*, *package*=None)`` imports a module. *name* is
|
|
a string containing the module or package's name. It's possible to do
|
|
relative imports by providing a string that begins with a ``.``
|
|
character, such as ``..utils.errors``. For relative imports, the
|
|
*package* argument must be provided and is the name of the package that
|
|
will be used as the anchor for
|
|
the relative import. :func:`import_module` both inserts the imported
|
|
module into ``sys.modules`` and returns the module object.
|
|
|
|
Here are some examples::
|
|
|
|
>>> from importlib import import_module
|
|
>>> anydbm = import_module('anydbm') # Standard absolute import
|
|
>>> anydbm
|
|
<module 'anydbm' from '/p/python/Lib/anydbm.py'>
|
|
>>> # Relative import
|
|
>>> sysconfig = import_module('..sysconfig', 'distutils.command')
|
|
>>> sysconfig
|
|
<module 'distutils.sysconfig' from '/p/python/Lib/distutils/sysconfig.pyc'>
|
|
|
|
:mod:`importlib` was implemented by Brett Cannon and introduced in
|
|
Python 3.1.
|
|
|
|
|
|
ttk: Themed Widgets for Tk
|
|
--------------------------
|
|
|
|
Tcl/Tk 8.5 includes a set of themed widgets that re-implement basic Tk
|
|
widgets but have a more customizable appearance and can therefore more
|
|
closely resemble the native platform's widgets. This widget
|
|
set was originally called Tile, but was renamed to Ttk (for "themed Tk")
|
|
on being added to Tcl/Tck release 8.5.
|
|
|
|
XXX write a brief discussion and an example here.
|
|
|
|
The :mod:`ttk` module was written by Guilherme Polo and added in
|
|
:issue:`2983`. An alternate version called ``Tile.py``, written by
|
|
Martin Franklin and maintained by Kevin Walzer, was proposed for
|
|
inclusion in :issue:`2618`, but the authors argued that Guilherme
|
|
Polo's work was more comprehensive.
|
|
|
|
.. ======================================================================
|
|
|
|
|
|
Build and C API Changes
|
|
=======================
|
|
|
|
Changes to Python's build process and to the C API include:
|
|
|
|
* If you use the :file:`.gdbinit` file provided with Python,
|
|
the "pyo" macro in the 2.7 version will now work when the thread being
|
|
debugged doesn't hold the GIL; the macro will now acquire it before printing.
|
|
(Contributed by Victor Stinner; :issue:`3632`.)
|
|
|
|
* :cfunc:`Py_AddPendingCall` is now thread-safe, letting any
|
|
worker thread submit notifications to the main Python thread. This
|
|
is particularly useful for asynchronous IO operations.
|
|
(Contributed by Kristjan Valur Jonsson; :issue:`4293`.)
|
|
|
|
* Global symbols defined by the :mod:`ctypes` module are now prefixed
|
|
with ``Py`, or with ``_ctypes``. (Implemented by Thomas
|
|
Heller; :issue:`3102`.)
|
|
|
|
* The :program:`configure` script now checks for floating-point rounding bugs
|
|
on certain 32-bit Intel chips and defines a :cmacro:`X87_DOUBLE_ROUNDING`
|
|
preprocessor definition. No code currently uses this definition,
|
|
but it's available if anyone wishes to use it.
|
|
(Added by Mark Dickinson; :issue:`2937`.)
|
|
|
|
.. ======================================================================
|
|
|
|
Port-Specific Changes: Windows
|
|
-----------------------------------
|
|
|
|
* The :mod:`msvcrt` module now contains some constants from
|
|
the :file:`crtassem.h` header file:
|
|
:data:`CRT_ASSEMBLY_VERSION`,
|
|
:data:`VC_ASSEMBLY_PUBLICKEYTOKEN`,
|
|
and :data:`LIBRARIES_ASSEMBLY_NAME_PREFIX`.
|
|
(Contributed by David Cournapeau; :issue:`4365`.)
|
|
|
|
* The new :cfunc:`_beginthreadex` API is used to start threads, and
|
|
the native thread-local storage functions are now used.
|
|
(Contributed by Kristjan Valur Jonsson; :issue:`3582`.)
|
|
|
|
.. ======================================================================
|
|
|
|
Port-Specific Changes: Mac OS X
|
|
-----------------------------------
|
|
|
|
* The ``/Library/Python/2.7/site-packages`` is now appended to
|
|
``sys.path``, in order to share added packages between the system
|
|
installation and a user-installed copy of the same version.
|
|
(Changed by Ronald Oussoren; :issue:`4865`.)
|
|
|
|
|
|
Other Changes and Fixes
|
|
=======================
|
|
|
|
* When importing a module from a :file:`.pyc` or :file:`.pyo` file
|
|
with an existing :file:`.py` counterpart, the :attr:`co_filename`
|
|
attributes of the resulting code objects are overwritten when the
|
|
original filename is obsolete. This can happen if the file has been
|
|
renamed, moved, or is accessed through different paths. (Patch by
|
|
Ziga Seilnacht and Jean-Paul Calderone; :issue:`1180193`.)
|
|
|
|
* The :file:`regrtest.py` script now takes a :option:`--randseed=`
|
|
switch that takes an integer that will be used as the random seed
|
|
for the :option:`-r` option that executes tests in random order.
|
|
The :option:`-r` option also now reports the seed that was used
|
|
(Added by Collin Winter.)
|
|
|
|
* The :file:`regrtest.py` script now takes a :option:`-j` switch
|
|
that takes an integer specifying how many tests run in parallel. This
|
|
allows to shorten the total runtime on multi-core machines.
|
|
This option is compatible with several other options, including the
|
|
:option:`-R` switch which is known to produce long runtimes.
|
|
(Added by Antoine Pitrou, :issue:`6152`.)
|
|
|
|
.. ======================================================================
|
|
|
|
Porting to Python 2.7
|
|
=====================
|
|
|
|
This section lists previously described changes and other bugfixes
|
|
that may require changes to your code:
|
|
|
|
* Because of an optimization for the :keyword:`with` statement, the special
|
|
methods :meth:`__enter__` and :meth:`__exit__` must belong to the object's
|
|
type, and cannot be directly attached to the object's instance. This
|
|
affects new-styles classes (derived from :class:`object`) and C extension
|
|
types. (:issue:`6101`.)
|
|
|
|
.. ======================================================================
|
|
|
|
|
|
.. _acks27:
|
|
|
|
Acknowledgements
|
|
================
|
|
|
|
The author would like to thank the following people for offering
|
|
suggestions, corrections and assistance with various drafts of this
|
|
article: no one yet.
|
|
|