This saves the maintainer some effort going through the SVN logs
when researching a change.
-This article explains the new features in Python 2.7.
-No release schedule has been decided yet for 2.7.
+This article explains the new features in Python 2.7. No release
+schedule has been decided yet for 2.7; the schedule will eventually be
+described in :pep:`373`.
.. Compare with previous release in 2 - 3 sentences here.
add hyperlink when the documentation becomes available online.
-Python 3.1
-================
+.. _whatsnew27-python31:
+
+Python 3.1 Features
+=======================
Much as Python 2.6 incorporated features from Python 3.0,
-version 2.7 is influenced by features from 3.1.
+version 2.7 incorporates some of the new features
+in Python 3.1. The 2.x series continues to provide tools
+for migrating to the 3.x series.
+
+A partial list of 3.1 features that were backported to 2.7:
-XXX mention importlib; anything else?
+* A version of the :mod:`io` library, rewritten in C for performance.
+* The ordered-dictionary type described in :ref:`pep-0372`.
+* The new format specified described in :ref:`pep-0378`.
+* The :class:`memoryview` object.
+* A small subset of the :mod:`importlib` module `described below <#importlib-section>`__.
One porting change: the :option:`-3` switch now automatically
enables the :option:`-Qwarn` switch that causes warnings
about using classic division with integers and long integers.
+Other new Python3-mode warnings include:
+
+* :func:`operator.isCallable` and :func:`operator.sequenceIncludes`,
+ which are not supported in 3.x.
+
.. ========================================================================
.. Large, PEP-level features and changes should be described here.
.. ========================================================================
+.. _pep-0372:
+
PEP 372: Adding an ordered dictionary to collections
====================================================
-XXX write this
+Regular Python dictionaries iterate over key/value pairs in arbitrary order.
+Over the years, a number of authors have written alternative implementations
+that remember the order that the keys were originally inserted. Based on
+the experiences from those implementations, a new
+:class:`collections.OrderedDict` class has been introduced.
+
+The :class:`OrderedDict` API is substantially the same as regular dictionaries
+but will iterate over keys and values in a guaranteed order depending on
+when a key was first inserted::
+
+ >>> from collections import OrderedDict
+ >>> d = OrderedDict([('first', 1), ('second', 2),
+ ... ('third', 3)])
+ >>> d.items()
+ [('first', 1), ('second', 2), ('third', 3)]
+
+If a new entry overwrites an existing entry, the original insertion
+position is left unchanged::
+
+ >>> d['second'] = 4
+ >>> d.items()
+ [('first', 1), ('second', 4), ('third', 3)]
+
+Deleting an entry and reinserting it will move it to the end::
+
+ >>> del d['second']
+ >>> d['second'] = 5
+ >>> d.items()
+ [('first', 1), ('third', 3), ('second', 5)]
+
+The :meth:`popitem` method has an optional *last* argument
+that defaults to True. If *last* is True, the most recently
+added key is returned and removed; if it's False, the
+oldest key is selected::
+
+ >>> od = OrderedDict([(x,0) for x in range(20)])
+ >>> od.popitem()
+ (19, 0)
+ >>> od.popitem()
+ (18, 0)
+ >>> od.popitem(False)
+ (0, 0)
+ >>> od.popitem(False)
+ (1, 0)
+
+Comparing two ordered dictionaries checks both the keys and values,
+and requires that the insertion order was the same::
+
+ >>> od1 = OrderedDict([('first', 1), ('second', 2),
+ ... ('third', 3)])
+ >>> od2 = OrderedDict([('third', 3), ('first', 1),
+ ... ('second', 2)])
+ >>> od1==od2
+ False
+ >>> # Move 'third' key to the end
+ >>> del od2['third'] ; od2['third'] = 3
+ >>> od1==od2
+ True
+
+Comparing an :class:`OrderedDict` with a regular dictionary
+ignores the insertion order and just compares the keys and values.
+
+How does the :class:`OrderedDict` work? It maintains a doubly-linked
+list of keys, appending new keys to the list as they're inserted. A
+secondary dictionary maps keys to their corresponding list node, so
+deletion doesn't have to traverse the entire linked list and therefore
+remains O(1).
+
+.. XXX check O(1)-ness with Raymond
+
+The standard library now supports use of ordered dictionaries in several
+modules. The :mod:`configparser` module uses them by default. This lets
+configuration files be read, modified, and then written back in their original
+order. The *_asdict()* method for :func:`collections.namedtuple` now
+returns an ordered dictionary with the values appearing in the same order as
+the underlying tuple indicies. The :mod:`json` module is being built-out with
+an *object_pairs_hook* to allow OrderedDicts to be built by the decoder.
+Support was also added for third-party tools like `PyYAML <http://pyyaml.org/>`_.
+
+.. seealso::
+
+ :pep:`372` - Adding an ordered dictionary to collections
+ PEP written by Armin Ronacher and Raymond Hettinger;
+ implemented by Raymond Hettinger.
+
+.. _pep-0378:
+
+PEP 378: Format Specifier for Thousands Separator
+====================================================
+
+To make program output more readable, it can be useful to add
+separators to large numbers and render them as
+18,446,744,073,709,551,616 instead of 18446744073709551616.
+
+The fully general solution for doing this is the :mod:`locale` module,
+which can use different separators ("," in North America, "." in
+Europe) and different grouping sizes, but :mod:`locale` is complicated
+to use and unsuitable for multi-threaded applications where different
+threads are producing output for different locales.
+
+Therefore, a simple comma-grouping mechanism has been added to the
+mini-language used by the string :meth:`format` method. When
+formatting a floating-point number, simply include a comma between the
+width and the precision::
+
+ >>> '{:20,.2}'.format(f)
+ '18,446,744,073,709,551,616.00'
+
+This mechanism is not adaptable at all; commas are always used as the
+separator and the grouping is always into three-digit groups. The
+comma-formatting mechanism isn't as general as the :mod:`locale`
+module, but it's easier to use.
-Several modules will now use :class:`OrderedDict` by default. The
-:mod:`ConfigParser` module uses :class:`OrderedDict` for the list
-of sections and the options within a section.
-The :meth:`namedtuple._asdict` method returns an :class:`OrderedDict`
-as well.
+.. XXX "Format String Syntax" in string.rst could use many more examples.
+.. seealso::
+
+ :pep:`378` - Format Specifier for Thousands Separator
+ PEP written by Raymond Hettinger; implemented by Eric Smith.
Other Language Changes
======================
Some smaller changes made to the core Python language are:
-* :meth:`str.format` method now supports automatic numbering of the replacement
+* The :keyword:`with` statement can now use multiple context managers
+ in one statement. Context managers are processed from left to right
+ and each one is treated as beginning a new :keyword:`with` statement.
+ This means that::
+
+ with A() as a, B() as b:
+ ... suite of statements ...
+
+ is equivalent to::
+
+ with A() as a:
+ with B() as b:
+ ... suite of statements ...
+
+ The :func:`contextlib.nested` function provides a very similar
+ function, so it's no longer necessary and has been deprecated.
+
+ (Proposed in http://codereview.appspot.com/53094; implemented by
+ Georg Brandl.)
+
+* The :meth:`str.format` method now supports automatic numbering of the replacement
fields. This makes using :meth:`str.format` more closely resemble using
``%s`` formatting::
specifier will use the next argument, and so on. You can't mix auto-numbering
and explicit numbering -- either number all of your specifier fields or none
of them -- but you can mix auto-numbering and named fields, as in the second
- example above. (Contributed by Eric Smith; :issue`5237`.)
+ example above. (Contributed by Eric Smith; :issue:`5237`.)
+
+ Complex numbers now correctly support usage with :func:`format`.
+ Specifying a precision or comma-separation applies to both the real
+ and imaginary parts of the number, but a specified field width and
+ alignment is applied to the whole of the resulting ``1.5+3j``
+ output. (Contributed by Eric Smith; :issue:`1588`.)
* The :func:`int` and :func:`long` types gained a ``bit_length``
method that returns the number of bits necessary to represent
point now round differently, returning the floating-point number
closest to the number. This doesn't matter for small integers that
can be converted exactly, but for large numbers that will
- unavoidably lose precision, Python 2.7 will now approximate more
+ unavoidably lose precision, Python 2.7 now approximates more
closely. For example, Python 2.6 computed the following::
>>> n = 295147905179352891391
(Implemented by Mark Dickinson; :issue:`3166`.)
-* The :class:`bytearray` type's :meth:`translate` method will
- now accept ``None`` as its first argument. (Fixed by Georg Brandl;
+* The :class:`bytearray` type's :meth:`translate` method now accepts
+ ``None`` as its first argument. (Fixed by Georg Brandl;
:issue:`4759`.)
+* When using ``@classmethod`` and ``@staticmethod`` to wrap
+ methods as class or static methods, the wrapper object now
+ exposes the wrapped function as their :attr:`__func__` attribute.
+ (Contributed by Amaury Forgeot d'Arc, after a suggestion by
+ George Sakkis; :issue:`5982`.)
+
+* A new encoding named "cp720", used primarily for Arabic text, is now
+ supported. (Contributed by Alexander Belchenko and Amaury Forgeot
+ d'Arc; :issue:`1616979`.)
+
.. ======================================================================
and benchmark. The new mechanism is only supported on certain
compilers, such as gcc, SunPro, and icc.
+* A new opcode was added to perform the initial setup for
+ :keyword:`with` statements, looking up the :meth:`__enter__` and
+ :meth:`__exit__` methods. (Contributed by Benjamin Peterson.)
+
* The garbage collector now performs better when many objects are
being allocated without deallocating any. A full garbage collection
pass is only performed when the middle generation has been collected
considered and traversed by the collector.
(Contributed by Antoine Pitrou; :issue:`4688`.)
-* Integers are now stored internally either in base 2**15 or in base
+* Long integers are now stored internally either in base 2**15 or in base
2**30, the base being determined at build time. Previously, they
were always stored in base 2**15. Using base 2**30 gives
significant performance improvements on 64-bit machines, but
faster bytecode. (Patch by Antoine Pitrou, back-ported to 2.7
by Jeffrey Yasskin; :issue:`4715`.)
+* The :mod:`pickle` and :mod:`cPickle` modules now automatically
+ intern the strings used for attribute names, reducing memory usage
+ of the objects resulting from unpickling. (Contributed by Jake
+ McGuire; :issue:`5084`.)
+
+* The :mod:`cPickle` module now special-cases dictionaries,
+ nearly halving the time required to pickle them.
+ (Contributed by Collin Winter; :issue:`5670`.)
+
+* Converting an integer or long integer to a decimal string was made
+ faster by special-casing base 10 instead of using a generalized
+ conversion function that supports arbitrary bases.
+ (Patch by Gawain Bolton; :issue:`6713`.)
+
+
.. ======================================================================
New and Improved Modules
:file:`Misc/NEWS` file in the source tree for a more complete list of
changes, or look through the Subversion logs for all the details.
+* The :mod:`bdb` module's base debugging class :class:`Bdb`
+ gained a feature for skipping modules. The constructor
+ now takes an iterable containing glob-style patterns such as
+ ``django.*``; the debugger will not step into stack frames
+ from a module that matches one of these patterns.
+ (Contributed by Maru Newby after a suggestion by
+ Senthil Kumaran; :issue:`5142`.)
+
* The :mod:`bz2` module's :class:`BZ2File` now supports the context
management protocol, so you can write ``with bz2.BZ2File(...) as f: ...``.
(Contributed by Hagen Fuerstenau; :issue:`3860`.)
Contributed by Raymond Hettinger; :issue:`1696199`.
+ The new `OrderedDict` class is described in the earlier section
+ :ref:`pep-0372`.
+
The :class:`namedtuple` class now has an optional *rename* parameter.
If *rename* is true, field names that are invalid because they've
been repeated or that aren't legal Python identifiers will be
The :class:`deque` data type now exposes its maximum length as the
read-only :attr:`maxlen` attribute. (Added by Raymond Hettinger.)
-* In Distutils, :func:`distutils.sdist.add_defaults` now uses
+* The :mod:`ctypes` module now always converts ``None`` to a C NULL
+ pointer for arguments declared as pointers. (Changed by Thomas
+ Heller; :issue:`4606`.)
+
+* New method: the :class:`Decimal` class gained a
+ :meth:`from_float` class method that performs an exact conversion
+ of a floating-point number to a :class:`Decimal`.
+ Note that this is an **exact** conversion that strives for the
+ closest decimal approximation to the floating-point representation's value;
+ the resulting decimal value will therefore still include the inaccuracy,
+ if any.
+ For example, ``Decimal.from_float(0.1)`` returns
+ ``Decimal('0.1000000000000000055511151231257827021181583404541015625')``.
+ (Implemented by Raymond Hettinger; :issue:`4796`.)
+
+ The constructor for :class:`Decimal` now accepts non-European
+ Unicode characters, such as Arabic-Indic digits. (Contributed by
+ Mark Dickinson; :issue:`6595`.)
+
+ When using :class:`Decimal` instances with a string's
+ :meth:`format` method, the default alignment was previously
+ left-alignment. This has been changed to right-alignment, which seems
+ more sensible for numeric types. (Changed by Mark Dickinson; :issue:`6857`.)
+
+* Distutils is being more actively developed, thanks to Tarek Ziade
+ has taken over maintenance of the package. A new
+ :file:`setup.py` subcommand, ``check``, will
+ check that the arguments being passed to the :func:`setup` function
+ are complete and correct (:issue:`5732`).
+
+ :func:`distutils.sdist.add_defaults` now uses
*package_dir* and *data_files* to create the MANIFEST file.
- :mod:`distutils.sysconfig` will now read the :envvar:`AR`
- environment variable.
+ :mod:`distutils.sysconfig` now reads the :envvar:`AR` and
+ :envvar:`ARFLAGS` environment variables.
+
+ .. ARFLAGS done in #5941
It is no longer mandatory to store clear-text passwords in the
:file:`.pypirc` file when registering and uploading packages to PyPI. As long
process, but instead simply not install the failing extension.
(Contributed by Georg Brandl; :issue:`5583`.)
-* New method: the :class:`Decimal` class gained a
- :meth:`from_float` class method that performs an exact conversion
- of a floating-point number to a :class:`Decimal`.
- Note that this is an **exact** conversion that strives for the
- closest decimal approximation to the floating-point representation's value;
- the resulting decimal value will therefore still include the inaccuracy,
- if any.
- For example, ``Decimal.from_float(0.1)`` returns
- ``Decimal('0.1000000000000000055511151231257827021181583404541015625')``.
- (Implemented by Raymond Hettinger; :issue:`4796`.)
-
-* The :class:`Fraction` class will now accept two rational numbers
+* The :class:`Fraction` class now accepts two rational numbers
as arguments to its constructor.
(Implemented by Mark Dickinson; :issue:`5812`.)
recorded in a gzipped file by providing an optional timestamp to
the constructor. (Contributed by Jacques Frechet; :issue:`4272`.)
-* The :class:`io.FileIO` class now raises an :exc:`OSError` when passed
+* The :mod:`hashlib` module was inconsistent about accepting
+ input as a Unicode object or an object that doesn't support
+ the buffer protocol. The behavior was different depending on
+ whether :mod:`hashlib` was using an external OpenSSL library
+ or its built-in implementations. Python 2.7 makes the
+ behavior consistent, always rejecting such objects by raising a
+ :exc:`TypeError`. (Fixed by Gregory P. Smith; :issue:`3745`.)
+
+* The default :class:`HTTPResponse` class used by the :mod:`httplib` module now
+ supports buffering, resulting in much faster reading of HTTP responses.
+ (Contributed by Kristjan Valur Jonsson; :issue:`4879`.)
+
+* The :mod:`imaplib` module now supports IPv6 addresses.
+ (Contributed by Derek Morr; :issue:`1655`.)
+
+* The :mod:`io` library has been upgraded to the version shipped with
+ Python 3.1. For 3.1, the I/O library was entirely rewritten in C
+ and is 2 to 20 times faster depending on the task at hand. The
+ original Python version was renamed to the :mod:`_pyio` module.
+
+ One minor resulting change: the :class:`io.TextIOBase` class now
+ has an :attr:`errors` attribute giving the error setting
+ used for encoding and decoding errors (one of ``'strict'``, ``'replace'``,
+ ``'ignore'``).
+
+ The :class:`io.FileIO` class now raises an :exc:`OSError` when passed
an invalid file descriptor. (Implemented by Benjamin Peterson;
:issue:`4991`.)
with any object literal that decodes to a list of pairs.
(Contributed by Raymond Hettinger; :issue:`5381`.)
+* New functions: the :mod:`math` module now has
+ a :func:`gamma` function.
+ (Contributed by Mark Dickinson and nirinA raseliarison; :issue:`3366`.)
+
* The :mod:`multiprocessing` module's :class:`Manager*` classes
can now be passed a callable that will be called whenever
a subprocess is started, along with a set of arguments that will be
passed to the callable.
(Contributed by lekma; :issue:`5585`.)
+* The :mod:`nntplib` module now supports IPv6 addresses.
+ (Contributed by Derek Morr; :issue:`1664`.)
+
* The :mod:`pydoc` module now has help for the various symbols that Python
uses. You can now do ``help('<<')`` or ``help('@')``, for example.
(Contributed by David Laban; :issue:`4739`.)
now accept an optional *flags* argument, for consistency with the
other functions in the module. (Added by Gregory P. Smith.)
+* The :mod:`shutil` module's :func:`copyfile` and :func:`copytree`
+ functions now raises a :exc:`SpecialFileError` exception when
+ asked to copy a named pipe. Previously the code would treat
+ named pipes like a regular file by opening them for reading, and
+ this would block indefinitely. (Fixed by Antoine Pitrou; :issue:`3002`.)
+
+* New functions: in the :mod:`site` module, three new functions
+ return various site- and user-specific paths.
+ :func:`getsitepackages` returns a list containing all
+ global site-packages directories, and
+ :func:`getusersitepackages` returns the path of the user's
+ site-packages directory.
+ :func:`getuserbase` returns the value of the :envvar:``USER_BASE``
+ environment variable, giving the path to a directory that can be used
+ to store data.
+ (Contributed by Tarek Ziade; :issue:`6693`.)
+
+* The :mod:`SocketServer` module's :class:`TCPServer` class now
+ has a :attr:`disable_nagle_algorithm` class attribute.
+ The default value is False; if overridden to be True,
+ new request connections will have the TCP_NODELAY option set to
+ prevent buffering many small sends into a single TCP packet.
+ (Contributed by Kristjan Valur Jonsson; :issue:`6192`.)
+
+* The :mod:`struct` module will no longer silently ignore overflow
+ errors when a value is too large for a particular integer format
+ code (one of ``bBhHiIlLqQ``); it now always raises a
+ :exc:`struct.error` exception. (Changed by Mark Dickinson;
+ :issue:`1523`.)
+
* New function: the :mod:`subprocess` module's
:func:`check_output` runs a command with a specified set of arguments
and returns the command's output as a string when the command runs without
named ``major``, ``minor``, ``micro``, ``releaselevel``, and ``serial``.
(Contributed by Ross Light; :issue:`4285`.)
+* The :mod:`tarfile` module now supports filtering the :class:`TarInfo`
+ objects being added to a tar file. When you call :meth:`TarFile.add`,
+ instance, you may supply an optional *filter* argument
+ that's a callable. The *filter* callable will be passed the
+ :class:`TarInfo` for every file being added, and can modify and return it.
+ If the callable returns ``None``, the file will be excluded from the
+ resulting archive. This is more powerful than the existing
+ *exclude* argument, which has therefore been deprecated.
+ (Added by Lars Gustaebel; :issue:`6856`.)
+
* The :mod:`threading` module's :meth:`Event.wait` method now returns
the internal flag on exit. This means the method will usually
return true because :meth:`wait` is supposed to block until the
internal flag becomes true. The return value will only be false if
a timeout was provided and the operation timed out.
- (Contributed by XXX; :issue:`1674032`.)
-
-* The :mod:`unittest` module was enhanced in several ways.
- The progress messages will now show 'x' for expected failures
- and 'u' for unexpected successes when run in verbose mode.
- (Contributed by Benjamin Peterson.)
- Test cases can raise the :exc:`SkipTest` exception to skip a test.
- (:issue:`1034053`.)
-
- The error messages for :meth:`assertEqual`,
- :meth:`assertTrue`, and :meth:`assertFalse`
- failures now provide more information. If you set the
- :attr:`longMessage` attribute of your :class:`TestCase` classes to
- true, both the standard error message and any additional message you
- provide will be printed for failures. (Added by Michael Foord; :issue:`5663`.)
-
- The :meth:`assertRaises` and :meth:`failUnlessRaises` methods now
- return a context handler when called without providing a callable
- object to run. For example, you can write this::
-
- with self.assertRaises(KeyError):
- raise ValueError
-
- (Implemented by Antoine Pitrou; :issue:`4444`.)
-
- The methods :meth:`addCleanup` and :meth:`doCleanups` were added.
- :meth:`addCleanup` allows you to add cleanup functions that
- will be called unconditionally (after :meth:`setUp` if
- :meth:`setUp` fails, otherwise after :meth:`tearDown`). This allows
- for much simpler resource allocation and deallocation during tests.
- :issue:`5679`
-
- A number of new methods were added that provide more specialized
- tests. Many of these methods were written by Google engineers
- for use in their test suites; Gregory P. Smith, Michael Foord, and
- GvR worked on merging them into Python's version of :mod:`unittest`.
-
- * :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*.
-
- * :meth:`assertAlmostEqual` and :meth:`assertNotAlmostEqual` short-circuit
- (automatically pass or fail without checking decimal places) if the objects
- are equal.
-
- * :meth:`loadTestsFromName` properly honors the ``suiteClass`` attribute of
- the :class:`TestLoader`. (Fixed by Mark Roddy; :issue:`6866`.)
-
- * 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
+ (Contributed by Tim Lesher; :issue:`1674032`.)
+
+* The :func:`is_zipfile` function in the :mod:`zipfile` module now
+ accepts 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`.)
+* The :mod:`ftplib` module gains the ability to establish secure FTP
+ connections using TLS encapsulation of authentication as well as
+ subsequent control and data transfers. This is provided by the new
+ :class:`ftplib.FTP_TLS` class.
+ (Contributed by Giampaolo Rodola', :issue:`2054`.)
+
.. ======================================================================
.. whole new modules get described in subsections here
+Unit Testing Enhancements
+---------------------------------
+
+The :mod:`unittest` module was enhanced in several ways.
+The progress messages now shows 'x' for expected failures
+and 'u' for unexpected successes when run in verbose mode.
+(Contributed by Benjamin Peterson.)
+Test cases can raise the :exc:`SkipTest` exception to skip a test.
+(:issue:`1034053`.)
+
+.. XXX describe test discovery (Contributed by Michael Foord; :issue:`6001`.)
+
+The error messages for :meth:`assertEqual`,
+:meth:`assertTrue`, and :meth:`assertFalse`
+failures now provide more information. If you set the
+:attr:`longMessage` attribute of your :class:`TestCase` classes to
+true, both the standard error message and any additional message you
+provide will be printed for failures. (Added by Michael Foord; :issue:`5663`.)
+
+The :meth:`assertRaises` and :meth:`failUnlessRaises` methods now
+return a context handler when called without providing a callable
+object to run. For example, you can write this::
+
+ with self.assertRaises(KeyError):
+ raise ValueError
+
+(Implemented by Antoine Pitrou; :issue:`4444`.)
+
+The methods :meth:`addCleanup` and :meth:`doCleanups` were added.
+:meth:`addCleanup` allows you to add cleanup functions that
+will be called unconditionally (after :meth:`setUp` if
+:meth:`setUp` fails, otherwise after :meth:`tearDown`). This allows
+for much simpler resource allocation and deallocation during tests.
+:issue:`5679`
+
+A number of new methods were added that provide more specialized
+tests. Many of these methods were written by Google engineers
+for use in their test suites; Gregory P. Smith, Michael Foord, and
+GvR worked on merging them into Python's version of :mod:`unittest`.
+
+* :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*.
+
+* :meth:`assertAlmostEqual` and :meth:`assertNotAlmostEqual` short-circuit
+ (automatically pass or fail without checking decimal places) if the objects
+ are equal.
+
+* :meth:`loadTestsFromName` properly honors the ``suiteClass`` attribute of
+ the :class:`TestLoader`. (Fixed by Mark Roddy; :issue:`6866`.)
+
+* 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.
+
+With all these changes, the :file:`unittest.py` was becoming awkwardly
+large, so the module was turned into a package and the code split into
+several files (by Benjamin Peterson). This doesn't affect how the
+module is imported.
+
+
+.. _importlib-section:
+
importlib: Importing Modules
------------------------------
: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
+``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
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.
+ the "pyo" macro in the 2.7 version now works correctly when the thread being
+ debugged doesn't hold the GIL; the macro now acquires it before printing.
(Contributed by Victor Stinner; :issue:`3632`.)
* :cfunc:`Py_AddPendingCall` is now thread-safe, letting any
is particularly useful for asynchronous IO operations.
(Contributed by Kristjan Valur Jonsson; :issue:`4293`.)
+* New function: :cfunc:`PyCode_NewEmpty` creates an empty code object;
+ only the filename, function name, and first line number are required.
+ This is useful to extension modules that are attempting to
+ construct a more useful traceback stack. Previously such
+ extensions needed to call :cfunc:`PyCode_New`, which had many
+ more arguments. (Added by Jeffrey Yasskin.)
+
+* New function: :cfunc:`PyFrame_GetLineNumber` takes a frame object
+ and returns the line number that the frame is currently executing.
+ Previously code would need to get the index of the bytecode
+ instruction currently executing, and then look up the line number
+ corresponding to that address. (Added by Jeffrey Yasskin.)
+
+* New macros: the Python header files now define the following macros:
+ :cmacro:`Py_ISALNUM`,
+ :cmacro:`Py_ISALPHA`,
+ :cmacro:`Py_ISDIGIT`,
+ :cmacro:`Py_ISLOWER`,
+ :cmacro:`Py_ISSPACE`,
+ :cmacro:`Py_ISUPPER`,
+ :cmacro:`Py_ISXDIGIT`,
+ and :cmacro:`Py_TOLOWER`, :cmacro:`Py_TOUPPER`.
+ All of these functions are analogous to the C
+ standard macros for classifying characters, but ignore the current
+ locale setting, because in
+ several places Python needs to analyze characters in a
+ locale-independent way. (Added by Eric Smith;
+ :issue:`5793`.)
+
+ .. XXX these macros don't seem to be described in the c-api docs.
+
+* The complicated interaction between threads and process forking has
+ been changed. Previously, the child process created by
+ :func:`os.fork` might fail because the child is created with only a
+ single thread running, the thread performing the :func:`os.fork`.
+ If other threads were holding a lock, such as Python's import lock,
+ when the fork was performed, the lock would still be marked as
+ "held" in the new process. But in the child process nothing would
+ ever release the lock, since the other threads weren't replicated,
+ and the child process would no longer be able to perform imports.
+
+ Python 2.7 now acquires the import lock before performing an
+ :func:`os.fork`, and will also clean up any locks created using the
+ :mod:`threading` module. C extension modules that have internal
+ locks, or that call :cfunc:`fork()` themselves, will not benefit
+ from this clean-up.
+
+ (Fixed by Thomas Wouters; :issue:`1590864`.)
+
* Global symbols defined by the :mod:`ctypes` module are now prefixed
- with ``Py`, or with ``_ctypes``. (Implemented by Thomas
+ with ``Py``, or with ``_ctypes``. (Implemented by Thomas
Heller; :issue:`3102`.)
* The :program:`configure` script now checks for floating-point rounding bugs
but it's available if anyone wishes to use it.
(Added by Mark Dickinson; :issue:`2937`.)
+* The build process now creates the necessary files for pkg-config
+ support. (Contributed by Clinton Roy; :issue:`3585`.)
+
+* The build process now supports Subversion 1.7. (Contributed by
+ Arfrever Frehtes Taifersar Arahesis; :issue:`6094`.)
+
.. ======================================================================
Port-Specific Changes: Windows
the native thread-local storage functions are now used.
(Contributed by Kristjan Valur Jonsson; :issue:`3582`.)
+* The :func:`os.listdir` function now correctly fails
+ for an empty path. (Fixed by Hirokazu Yamamoto; :issue:`5913`.)
+
.. ======================================================================
Port-Specific Changes: Mac OS X
-----------------------------------
-* The ``/Library/Python/2.7/site-packages`` is now appended to
+* The path ``/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`.)
* 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
+ The :option:`-r` option also 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.
+ allows reducing 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`.)
This section lists previously described changes and other bugfixes
that may require changes to your code:
+* When using :class:`Decimal` instances with a string's
+ :meth:`format` method, the default alignment was previously
+ left-alignment. This has been changed to right-alignment, which might
+ change the output of your programs.
+ (Changed by Mark Dickinson; :issue:`6857`.)
+
+ Another :meth:`format`-related change: the default precision used
+ for floating-point and complex numbers was changed from 6 decimal
+ places to 12, which matches the precision used by :func:`str`.
+ (Changed by Eric Smith; :issue:`5920`.)
+
* 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
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