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Diffstat (limited to 'Doc/whatsnew/2.7.rst')
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1 files changed, 520 insertions, 144 deletions
diff --git a/Doc/whatsnew/2.7.rst b/Doc/whatsnew/2.7.rst index bacf729..b791866 100644 --- a/Doc/whatsnew/2.7.rst +++ b/Doc/whatsnew/2.7.rst @@ -49,46 +49,195 @@ 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:: @@ -102,7 +251,13 @@ Some smaller changes made to the core Python language are: 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 @@ -125,7 +280,7 @@ Some smaller changes made to the core Python language are: 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 @@ -146,10 +301,20 @@ Some smaller changes made to the core Python language are: (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`.) + .. ====================================================================== @@ -164,6 +329,10 @@ Several performance enhancements have been added: 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 @@ -184,7 +353,7 @@ Several performance enhancements have been added: 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 @@ -227,6 +396,21 @@ Several performance enhancements have been added: 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 @@ -238,6 +422,14 @@ changes, sorted alphabetically by module name. Consult the :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`.) @@ -279,6 +471,9 @@ changes, or look through the Subversion logs for all the details. 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 @@ -295,10 +490,42 @@ changes, or look through the Subversion logs for all the details. 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 @@ -312,18 +539,7 @@ changes, or look through the Subversion logs for all the details. 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`.) @@ -338,7 +554,32 @@ changes, or look through the Subversion logs for all the details. 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`.) @@ -382,12 +623,19 @@ changes, or look through the Subversion logs for all the details. 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`.) @@ -396,6 +644,36 @@ changes, or look through the Subversion logs for all the details. 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 @@ -422,122 +700,151 @@ changes, or look through the Subversion logs for all the details. 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 ------------------------------ @@ -549,7 +856,7 @@ 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 +``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 @@ -607,8 +914,8 @@ 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. + 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 @@ -616,8 +923,57 @@ Changes to Python's build process and to the C API include: 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 @@ -626,6 +982,12 @@ Changes to Python's build process and to the C API include: 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 @@ -642,12 +1004,15 @@ 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`.) @@ -666,12 +1031,12 @@ Other Changes and Fixes * 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`.) @@ -684,6 +1049,17 @@ Porting to Python 2.7 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 |