[Python-checkins] r82809 - in python/branches/release31-maint/Doc/whatsnew: 2.7.rst index.rst
georg.brandl
python-checkins at python.org
Sun Jul 11 12:41:45 CEST 2010
Author: georg.brandl
Date: Sun Jul 11 12:41:44 2010
New Revision: 82809
Log:
2.7 came after 3.1, so its whatsnew document will confuse users who expect 2.7 features in 3.1.
Removed:
python/branches/release31-maint/Doc/whatsnew/2.7.rst
Modified:
python/branches/release31-maint/Doc/whatsnew/index.rst
Deleted: python/branches/release31-maint/Doc/whatsnew/2.7.rst
==============================================================================
--- python/branches/release31-maint/Doc/whatsnew/2.7.rst Sun Jul 11 12:41:44 2010
+++ (empty file)
@@ -1,2479 +0,0 @@
-****************************
- What's New in Python 2.7
-****************************
-
-:Author: A.M. Kuchling (amk at amk.ca)
-:Release: |release|
-:Date: |today|
-
-.. hyperlink all the methods & functions.
-
-.. T_STRING_INPLACE not described in main docs
-.. "Format String Syntax" in string.rst could use many more examples.
-
-.. $Id$
- Rules for maintenance:
-
- * Anyone can add text to this document. Do not spend very much time
- on the wording of your changes, because your text will probably
- get rewritten to some degree.
-
- * The maintainer will go through Misc/NEWS periodically and add
- changes; it's therefore more important to add your changes to
- Misc/NEWS than to this file.
-
- * This is not a complete list of every single change; completeness
- is the purpose of Misc/NEWS. Some changes I consider too small
- or esoteric to include. If such a change is added to the text,
- I'll just remove it. (This is another reason you shouldn't spend
- too much time on writing your addition.)
-
- * If you want to draw your new text to the attention of the
- maintainer, add 'XXX' to the beginning of the paragraph or
- section.
-
- * It's OK to just add a fragmentary note about a change. For
- example: "XXX Describe the transmogrify() function added to the
- socket module." The maintainer will research the change and
- write the necessary text.
-
- * You can comment out your additions if you like, but it's not
- necessary (especially when a final release is some months away).
-
- * Credit the author of a patch or bugfix. Just the name is
- sufficient; the e-mail address isn't necessary.
-
- * It's helpful to add the bug/patch number in a parenthetical comment.
-
- XXX Describe the transmogrify() function added to the socket
- module.
- (Contributed by P.Y. Developer; :issue:`12345`.)
-
- 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. The final
-release of 2.7 is currently scheduled for July 2010; the detailed
-schedule is described in :pep:`373`.
-
-Numeric handling has been improved in many ways, for both
-floating-point numbers and for the :class:`Decimal` class. There are
-some useful additions to the standard library, such as a greatly
-enhanced :mod:`unittest` module, the :mod:`argparse` module for
-parsing command-line options, convenient ordered-dictionary and
-:class:`Counter` classes in the :mod:`collections` module, and many
-other improvements.
-
-Python 2.7 is planned to be the last of the 2.x releases, so we worked
-on making it a good release for the long term. To help with porting
-to Python 3, several new features from the Python 3.x series have been
-included in 2.7.
-
-This article doesn't attempt to provide a complete specification of
-the new features, but instead provides a convenient overview. For
-full details, you should refer to the documentation for Python 2.7 at
-http://docs.python.org. If you want to understand the rationale for
-the design and implementation, refer to the PEP for a particular new
-feature or the issue on http://bugs.python.org in which a change was
-discussed. Whenever possible, "What's New in Python" links to the
-bug/patch item for each change.
-
-.. _whatsnew27-python31:
-
-The Future for Python 2.x
-=========================
-
-Python 2.7 is intended to be the last major release in the 2.x series.
-The Python maintainers are planning to focus their future efforts on
-the Python 3.x series.
-
-This means that 2.7 will remain in place for a long time, running
-production systems that have not been ported to Python 3.x.
-Two consequences of the long-term significance of 2.7 are:
-
-* It's very likely the 2.7 release will have a longer period of
- maintenance compared to earlier 2.x versions. Python 2.7 will
- continue to be maintained while the transition to 3.x continues, and
- the developers are planning to support Python 2.7 with bug-fix
- releases beyond the typical two years.
-
-* A policy decision was made to silence warnings only of interest to
- developers. :exc:`DeprecationWarning` and its
- descendants are now ignored unless otherwise requested, preventing
- users from seeing warnings triggered by an application. This change
- was also made in the branch that will become Python 3.2. (Discussed
- on stdlib-sig and carried out in :issue:`7319`.)
-
- In previous releases, :exc:`DeprecationWarning` messages were
- enabled by default, providing Python developers with a clear
- indication of where their code may break in a future major version
- of Python.
-
- However, there are increasingly many users of Python-based
- applications who are not directly involved in the development of
- those applications. :exc:`DeprecationWarning` messages are
- irrelevant to such users, making them worry about an application
- that's actually working correctly and burdening application developers
- with responding to these concerns.
-
- You can re-enable display of :exc:`DeprecationWarning` messages by
- running Python with the :option:`-Wdefault` (short form:
- :option:`-Wd`) switch, or by setting the :envvar:`PYTHONWARNINGS`
- environment variable to ``"default"`` (or ``"d"``) before running
- Python. Python code can also re-enable them
- by calling ``warnings.simplefilter('default')``.
-
-
-Python 3.1 Features
-=======================
-
-Much as Python 2.6 incorporated features from Python 3.0,
-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:
-
-* The syntax for set literals (``{1,2,3}`` is a mutable set).
-* Dictionary and set comprehensions (``{ i: i*2 for i in range(3)}``).
-* Multiple context managers in a single :keyword:`with` statement.
-* A new version of the :mod:`io` library, rewritten in C for performance.
-* The ordered-dictionary type described in :ref:`pep-0372`.
-* The new ``","`` format specifier described in :ref:`pep-0378`.
-* The :class:`memoryview` object.
-* A small subset of the :mod:`importlib` module,
- `described below <#importlib-section>`__.
-* Float-to-string and string-to-float conversions now round their
- results more correctly, and :func:`repr` of a floating-point
- number *x* returns a result that's guaranteed to round back to the
- same number when converted back to a float.
-* The :ctype:`PyCapsule` type, used to provide a C API for extension modules.
-* The :cfunc:`PyLong_AsLongAndOverflow` C API function.
-
-Other new Python3-mode warnings include:
-
-* :func:`operator.isCallable` and :func:`operator.sequenceIncludes`,
- which are not supported in 3.x, now trigger warnings.
-* The :option:`-3` switch now automatically
- enables the :option:`-Qwarn` switch that causes warnings
- about using classic division with integers and long integers.
-
-
-
-.. ========================================================================
-.. Large, PEP-level features and changes should be described here.
-.. ========================================================================
-
-.. _pep-0372:
-
-PEP 372: Adding an Ordered Dictionary to collections
-====================================================
-
-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, 2.7 introduces a new
-:class:`~collections.OrderedDict` class in the :mod:`collections` module.
-
-The :class:`~collections.OrderedDict` API provides the same interface as regular
-dictionaries but iterates 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:`~collections.OrderedDict.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(last=False)
- (0, 0)
- >>> od.popitem(last=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:`~collections.OrderedDict` with a regular dictionary
-ignores the insertion order and just compares the keys and values.
-
-How does the :class:`~collections.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).
-
-The standard library now supports use of ordered dictionaries in several
-modules.
-
-* The :mod:`ConfigParser` module uses them by default, meaning that
- configuration files can now read, modified, and then written back
- in their original order.
-
-* The :meth:`~collections.somenamedtuple._asdict()` method for
- :func:`collections.namedtuple` now returns an ordered dictionary with the
- values appearing in the same order as the underlying tuple indices.
-
-* The :mod:`json` module's :class:`~json.JSONDecoder` class
- constructor was extended with an *object_pairs_hook* parameter to
- allow :class:`OrderedDict` instances 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, rendering 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 :meth:`str.format` method. When
-formatting a floating-point number, simply include a comma between the
-width and the precision::
-
- >>> '{:20,.2f}'.format(18446744073709551616.0)
- '18,446,744,073,709,551,616.00'
-
-When formatting an integer, include the comma after the width:
-
- >>> '{:20,d}'.format(18446744073709551616)
- '18,446,744,073,709,551,616'
-
-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.
-
-.. seealso::
-
- :pep:`378` - Format Specifier for Thousands Separator
- PEP written by Raymond Hettinger; implemented by Eric Smith.
-
-PEP 389: The argparse Module for Parsing Command Lines
-======================================================
-
-The :mod:`argparse` module for parsing command-line arguments was
-added as a more powerful replacement for the
-:mod:`optparse` module.
-
-This means Python now supports three different modules for parsing
-command-line arguments: :mod:`getopt`, :mod:`optparse`, and
-:mod:`argparse`. The :mod:`getopt` module closely resembles the C
-library's :cfunc:`getopt` function, so it remains useful if you're writing a
-Python prototype that will eventually be rewritten in C.
-:mod:`optparse` becomes redundant, but there are no plans to remove it
-because there are many scripts still using it, and there's no
-automated way to update these scripts. (Making the :mod:`argparse`
-API consistent with :mod:`optparse`'s interface was discussed but
-rejected as too messy and difficult.)
-
-In short, if you're writing a new script and don't need to worry
-about compatibility with earlier versions of Python, use
-:mod:`argparse` instead of :mod:`optparse`.
-
-Here's an example::
-
- import argparse
-
- parser = argparse.ArgumentParser(description='Command-line example.')
-
- # Add optional switches
- parser.add_argument('-v', action='store_true', dest='is_verbose',
- help='produce verbose output')
- parser.add_argument('-o', action='store', dest='output',
- metavar='FILE',
- help='direct output to FILE instead of stdout')
- parser.add_argument('-C', action='store', type=int, dest='context',
- metavar='NUM', default=0,
- help='display NUM lines of added context')
-
- # Allow any number of additional arguments.
- parser.add_argument(nargs='*', action='store', dest='inputs',
- help='input filenames (default is stdin)')
-
- args = parser.parse_args()
- print args.__dict__
-
-Unless you override it, :option:`-h` and :option:`--help` switches
-are automatically added, and produce neatly formatted output::
-
- -> ./python.exe argparse-example.py --help
- usage: argparse-example.py [-h] [-v] [-o FILE] [-C NUM] [inputs [inputs ...]]
-
- Command-line example.
-
- positional arguments:
- inputs input filenames (default is stdin)
-
- optional arguments:
- -h, --help show this help message and exit
- -v produce verbose output
- -o FILE direct output to FILE instead of stdout
- -C NUM display NUM lines of added context
-
-As with :mod:`optparse`, the command-line switches and arguments
-are returned as an object with attributes named by the *dest* parameters::
-
- -> ./python.exe argparse-example.py -v
- {'output': None,
- 'is_verbose': True,
- 'context': 0,
- 'inputs': []}
-
- -> ./python.exe argparse-example.py -v -o /tmp/output -C 4 file1 file2
- {'output': '/tmp/output',
- 'is_verbose': True,
- 'context': 4,
- 'inputs': ['file1', 'file2']}
-
-:mod:`argparse` has much fancier validation than :mod:`optparse`; you
-can specify an exact number of arguments as an integer, 0 or more
-arguments by passing ``'*'``, 1 or more by passing ``'+'``, or an
-optional argument with ``'?'``. A top-level parser can contain
-sub-parsers to define subcommands that have different sets of
-switches, as in ``svn commit``, ``svn checkout``, etc. You can
-specify an argument's type as :class:`~argparse.FileType`, which will
-automatically open files for you and understands that ``'-'`` means
-standard input or output.
-
-.. seealso::
-
- `argparse module documentation <http://docs.python.org/dev/library/argparse.html>`__
-
- `Upgrading optparse code to use argparse <http://docs.python.org/dev/library/argparse.html#upgrading-optparse-code>`__
- Part of the Python documentation, describing how to convert
- code that uses :mod:`optparse`.
-
- :pep:`389` - argparse - New Command Line Parsing Module
- PEP written and implemented by Steven Bethard.
-
-PEP 391: Dictionary-Based Configuration For Logging
-====================================================
-
-.. XXX not documented in library reference yet; add link here once it's added.
-
-The :mod:`logging` module is very flexible; applications can define
-a tree of logging subsystems, and each logger in this tree can filter
-out certain messages, format them differently, and direct messages to
-a varying number of handlers.
-
-All this flexibility can require a lot of configuration. You can
-write Python statements to create objects and set their properties,
-but a complex set-up requires verbose but boring code.
-:mod:`logging` also supports a :func:`~logging.config.fileConfig`
-function that parses a file, but the file format doesn't support
-configuring filters, and it's messier to generate programmatically.
-
-Python 2.7 adds a :func:`~logging.config.dictConfig` function that
-uses a dictionary to configure logging. There are many ways to
-produce a dictionary from different sources: construct one with code;
-parse a file containing JSON; or use a YAML parsing library if one is
-installed.
-
-The following example configures two loggers, the root logger and a
-logger named "network". Messages sent to the root logger will be
-sent to the system log using the syslog protocol, and messages
-to the "network" logger will be written to a :file:`network.log` file
-that will be rotated once the log reaches 1Mb.
-
-::
-
- import logging
- import logging.config
-
- configdict = {
- 'version': 1, # Configuration schema in use; must be 1 for now
- 'formatters': {
- 'standard': {
- 'format': ('%(asctime)s %(name)-15s '
- '%(levelname)-8s %(message)s')}},
-
- 'handlers': {'netlog': {'backupCount': 10,
- 'class': 'logging.handlers.RotatingFileHandler',
- 'filename': '/logs/network.log',
- 'formatter': 'standard',
- 'level': 'INFO',
- 'maxBytes': 1024*1024},
- 'syslog': {'class': 'logging.handlers.SysLogHandler',
- 'formatter': 'standard',
- 'level': 'ERROR'}},
-
- # Specify all the subordinate loggers
- 'loggers': {
- 'network': {
- 'handlers': ['netlog']
- }
- },
- # Specify properties of the root logger
- 'root': {
- 'handlers': ['syslog']
- },
- }
-
- # Set up configuration
- logging.config.dictConfig(configdict)
-
- # As an example, log two error messages
- logger = logging.getLogger('/')
- logger.error('Database not found')
-
- netlogger = logging.getLogger('network')
- netlogger.error('Connection failed')
-
-Three smaller enhancements to the :mod:`logging` module, all
-implemented by Vinay Sajip, are:
-
-.. rev79293
-
-* The :class:`~logging.handlers.SysLogHandler` class now supports
- syslogging over TCP. The constructor has a *socktype* parameter
- giving the type of socket to use, either :const:`socket.SOCK_DGRAM`
- for UDP or :const:`socket.SOCK_STREAM` for TCP. The default
- protocol remains UDP.
-
-* :class:`Logger` instances gained a :meth:`getChild` method that retrieves a
- descendant logger using a relative path. For example,
- once you retrieve a logger by doing ``log = getLogger('app')``,
- calling ``log.getChild('network.listen')`` is equivalent to
- ``getLogger('app.network.listen')``.
-
-* The :class:`LoggerAdapter` class gained a :meth:`isEnabledFor` method
- that takes a *level* and returns whether the underlying logger would
- process a message of that level of importance.
-
-.. seealso::
-
- :pep:`391` - Dictionary-Based Configuration For Logging
- PEP written and implemented by Vinay Sajip.
-
-PEP 3106: Dictionary Views
-====================================================
-
-The dictionary methods :meth:`keys`, :meth:`values`, and :meth:`items`
-are different in Python 3.x. They return an object called a :dfn:`view`
-instead of a fully materialized list.
-
-It's not possible to change the return values of :meth:`keys`,
-:meth:`values`, and :meth:`items` in Python 2.7 because too much code
-would break. Instead the 3.x versions were added under the new names
-:meth:`viewkeys`, :meth:`viewvalues`, and :meth:`viewitems`.
-
-::
-
- >>> d = dict((i*10, chr(65+i)) for i in range(26))
- >>> d
- {0: 'A', 130: 'N', 10: 'B', 140: 'O', 20: ..., 250: 'Z'}
- >>> d.viewkeys()
- dict_keys([0, 130, 10, 140, 20, 150, 30, ..., 250])
-
-Views can be iterated over, but the key and item views also behave
-like sets. The ``&`` operator performs intersection, and ``|``
-performs a union::
-
- >>> d1 = dict((i*10, chr(65+i)) for i in range(26))
- >>> d2 = dict((i**.5, i) for i in range(1000))
- >>> d1.viewkeys() & d2.viewkeys()
- set([0.0, 10.0, 20.0, 30.0])
- >>> d1.viewkeys() | range(0, 30)
- set([0, 1, 130, 3, 4, 5, 6, ..., 120, 250])
-
-The view keeps track of the dictionary and its contents change as the
-dictionary is modified::
-
- >>> vk = d.viewkeys()
- >>> vk
- dict_keys([0, 130, 10, ..., 250])
- >>> d[260] = '&'
- >>> vk
- dict_keys([0, 130, 260, 10, ..., 250])
-
-However, note that you can't add or remove keys while you're iterating
-over the view::
-
- >>> for k in vk:
- ... d[k*2] = k
- ...
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- RuntimeError: dictionary changed size during iteration
-
-You can use the view methods in Python 2.x code, and the 2to3
-converter will change them to the standard :meth:`keys`,
-:meth:`values`, and :meth:`items` methods.
-
-.. seealso::
-
- :pep:`3106` - Revamping dict.keys(), .values() and .items()
- PEP written by Guido van Rossum.
- Backported to 2.7 by Alexandre Vassalotti; :issue:`1967`.
-
-
-PEP 3137: The memoryview Object
-====================================================
-
-The :class:`memoryview` object provides a view of another object's
-memory content that matches the :class:`bytes` type's interface.
-
- >>> import string
- >>> m = memoryview(string.letters)
- >>> m
- <memory at 0x37f850>
- >>> len(m) # Returns length of underlying object
- 52
- >>> m[0], m[25], m[26] # Indexing returns one byte
- ('a', 'z', 'A')
- >>> m2 = m[0:26] # Slicing returns another memoryview
- >>> m2
- <memory at 0x37f080>
-
-The content of the view can be converted to a string of bytes or
-a list of integers:
-
- >>> m2.tobytes()
- 'abcdefghijklmnopqrstuvwxyz'
- >>> m2.tolist()
- [97, 98, 99, 100, 101, 102, 103, ... 121, 122]
- >>>
-
-:class:`memoryview` objects allow modifying the underlying object if
-it's a mutable object.
-
- >>> m2[0] = 75
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- TypeError: cannot modify read-only memory
- >>> b = bytearray(string.letters) # Creating a mutable object
- >>> b
- bytearray(b'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
- >>> mb = memoryview(b)
- >>> mb[0] = '*' # Assign to view, changing the bytearray.
- >>> b[0:5] # The bytearray has been changed.
- bytearray(b'*bcde')
- >>>
-
-.. seealso::
-
- :pep:`3137` - Immutable Bytes and Mutable Buffer
- PEP written by Guido van Rossum.
- Implemented by Travis Oliphant, Antoine Pitrou and others.
- Backported to 2.7 by Antoine Pitrou; :issue:`2396`.
-
-
-
-Other Language Changes
-======================
-
-Some smaller changes made to the core Python language are:
-
-* The syntax for set literals has been backported from Python 3.x.
- Curly brackets are used to surround the contents of the resulting
- mutable set; set literals are
- distinguished from dictionaries by not containing colons and values.
- ``{}`` continues to represent an empty dictionary; use
- ``set()`` for an empty set.
-
- >>> {1,2,3,4,5}
- set([1, 2, 3, 4, 5])
- >>> set() # empty set
- set([])
- >>> {} # empty dict
- {}
-
- Backported by Alexandre Vassalotti; :issue:`2335`.
-
-* Dictionary and set comprehensions are another feature backported from
- 3.x, generalizing list/generator comprehensions to use
- the literal syntax for sets and dictionaries.
-
- >>> {x: x*x for x in range(6)}
- {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
- >>> {('a'*x) for x in range(6)}
- set(['', 'a', 'aa', 'aaa', 'aaaa', 'aaaaa'])
-
- Backported by Alexandre Vassalotti; :issue:`2333`.
-
-* 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.)
-
-* Conversions between floating-point numbers and strings are
- now correctly rounded on most platforms. These conversions occur
- in many different places: :func:`str` on
- floats and complex numbers; the :class:`float` and :class:`complex`
- constructors;
- numeric formatting; serializing and
- deserializing floats and complex numbers using the
- :mod:`marshal`, :mod:`pickle`
- and :mod:`json` modules;
- parsing of float and imaginary literals in Python code;
- and :class:`~decimal.Decimal`-to-float conversion.
-
- Related to this, the :func:`repr` of a floating-point number *x*
- now returns a result based on the shortest decimal string that's
- guaranteed to round back to *x* under correct rounding (with
- round-half-to-even rounding mode). Previously it gave a string
- based on rounding x to 17 decimal digits.
-
- .. maybe add an example?
-
- The rounding library responsible for this improvement works on
- Windows and on Unix platforms using the gcc, icc, or suncc
- compilers. There may be a small number of platforms where correct
- operation of this code cannot be guaranteed, so the code is not
- used on such systems. You can find out which code is being used
- by checking :data:`sys.float_repr_style`, which will be ``short``
- if the new code is in use and ``legacy`` if it isn't.
-
- Implemented by Eric Smith and Mark Dickinson, using David Gay's
- :file:`dtoa.c` library; :issue:`7117`.
-
-* Conversions from long integers and regular integers to floating
- 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 now approximates more
- closely. For example, Python 2.6 computed the following::
-
- >>> n = 295147905179352891391
- >>> float(n)
- 2.9514790517935283e+20
- >>> n - long(float(n))
- 65535L
-
- Python 2.7's floating-point result is larger, but much closer to the
- true value::
-
- >>> n = 295147905179352891391
- >>> float(n)
- 2.9514790517935289e+20
- >>> n - long(float(n))
- -1L
-
- (Implemented by Mark Dickinson; :issue:`3166`.)
-
- Integer division is also more accurate in its rounding behaviours. (Also
- implemented by Mark Dickinson; :issue:`1811`.)
-
-* Implicit coercion for complex numbers has been removed; the interpreter
- will no longer ever attempt to call a :meth:`__coerce__` method on complex
- objects. (Removed by Meador Inge and Mark Dickinson; :issue:`5211`.)
-
-* 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::
-
- >>> '{}:{}:{}'.format(2009, 04, 'Sunday')
- '2009:4:Sunday'
- >>> '{}:{}:{day}'.format(2009, 4, day='Sunday')
- '2009:4:Sunday'
-
- The auto-numbering takes the fields from left to right, so the first ``{...}``
- specifier will use the first argument to :meth:`str.format`, the next
- 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`.)
-
- Complex numbers now correctly support usage with :func:`format`,
- and default to being right-aligned.
- 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` and :issue:`7988`.)
-
- The 'F' format code now always formats its output using uppercase characters,
- so it will now produce 'INF' and 'NAN'.
- (Contributed by Eric Smith; :issue:`3382`.)
-
- A low-level change: the :meth:`object.__format__` method now triggers
- a :exc:`PendingDeprecationWarning` if it's passed a format string,
- because the :meth:`__format__` method for :class:`object` converts
- the object to a string representation and formats that. Previously
- the method silently applied the format string to the string
- representation, but that could hide mistakes in Python code. If
- you're supplying formatting information such as an alignment or
- precision, presumably you're expecting the formatting to be applied
- in some object-specific way. (Fixed by Eric Smith; :issue:`7994`.)
-
-* The :func:`int` and :func:`long` types gained a ``bit_length``
- method that returns the number of bits necessary to represent
- its argument in binary::
-
- >>> n = 37
- >>> bin(n)
- '0b100101'
- >>> n.bit_length()
- 6
- >>> n = 2**123-1
- >>> n.bit_length()
- 123
- >>> (n+1).bit_length()
- 124
-
- (Contributed by Fredrik Johansson and Victor Stinner; :issue:`3439`.)
-
-* The :keyword:`import` statement will no longer try a relative import
- if an absolute import (e.g. ``from .os import sep``) fails. This
- fixes a bug, but could possibly break certain :keyword:`import`
- statements that were only working by accident. (Fixed by Meador Inge;
- :issue:`7902`.)
-
-* It's now possible for a subclass of the built-in :class:`unicode` type
- to override the :meth:`__unicode__` method. (Implemented by
- Victor Stinner; :issue:`1583863`.)
-
-* The :class:`bytearray` type's :meth:`~bytearray.translate` method now accepts
- ``None`` as its first argument. (Fixed by Georg Brandl;
- :issue:`4759`.)
-
- .. bytearray doesn't seem to be documented
-
-* 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`.)
-
-* When a restricted set of attributes were set using ``__slots__``,
- deleting an unset attribute would not raise :exc:`AttributeError`
- as you would expect. Fixed by Benjamin Peterson; :issue:`7604`.)
-
-* Two new encodings are now supported: "cp720", used primarily for
- Arabic text; and "cp858", a variant of CP 850 that adds the euro
- symbol. (CP720 contributed by Alexander Belchenko and Amaury
- Forgeot d'Arc in :issue:`1616979`; CP858 contributed by Tim Hatch in
- :issue:`8016`.)
-
-* The :class:`file` object will now set the :attr:`filename` attribute
- on the :exc:`IOError` exception when trying to open a directory
- on POSIX platforms (noted by Jan Kaliszewski; :issue:`4764`), and
- now explicitly checks for and forbids writing to read-only file objects
- instead of trusting the C library to catch and report the error
- (fixed by Stefan Krah; :issue:`5677`).
-
-* The Python tokenizer now translates line endings itself, so the
- :func:`compile` built-in function now accepts code using any
- line-ending convention. Additionally, it no longer requires that the
- code end in a newline.
-
-* Extra parentheses in function definitions are illegal in Python 3.x,
- meaning that you get a syntax error from ``def f((x)): pass``. In
- Python3-warning mode, Python 2.7 will now warn about this odd usage.
- (Noted by James Lingard; :issue:`7362`.)
-
-* It's now possible to create weak references to old-style class
- objects. New-style classes were always weak-referenceable. (Fixed
- by Antoine Pitrou; :issue:`8268`.)
-
-* When a module object is garbage-collected, the module's dictionary is
- now only cleared if no one else is holding a reference to the
- dictionary (:issue:`7140`).
-
-.. ======================================================================
-
-.. _new-27-interpreter:
-
-Interpreter Changes
--------------------------------
-
-A new environment variable, :envvar:`PYTHONWARNINGS`,
-allows controlling warnings. It should be set to a string
-containing warning settings, equivalent to those
-used with the :option:`-W` switch, separated by commas.
-(Contributed by Brian Curtin; :issue:`7301`.)
-
-For example, the following setting will print warnings every time
-they occur, but turn warnings from the :mod:`Cookie` module into an
-error. (The exact syntax for setting an environment variable varies
-across operating systems and shells.)
-
-::
-
- export PYTHONWARNINGS=all,error:::Cookie:0
-
-.. ======================================================================
-
-
-Optimizations
--------------
-
-Several performance enhancements have been added:
-
-.. * A new :program:`configure` option, :option:`--with-computed-gotos`,
- compiles the main bytecode interpreter loop using a new dispatch
- mechanism that gives speedups of up to 20%, depending on the system
- 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 for one common usage
- pattern: when many objects are being allocated without deallocating
- any of them. This would previously take quadratic
- time for garbage collection, but now the number of full garbage collections
- is reduced as the number of objects on the heap grows.
- The new logic only performs a full garbage collection pass when
- the middle generation has been collected 10 times and when the
- number of survivor objects from the middle generation exceeds 10% of
- the number of objects in the oldest generation. (Suggested by Martin
- von Löwis and implemented by Antoine Pitrou; :issue:`4074`.)
-
-* The garbage collector tries to avoid tracking simple containers
- which can't be part of a cycle. In Python 2.7, this is now true for
- tuples and dicts containing atomic types (such as ints, strings,
- etc.). Transitively, a dict containing tuples of atomic types won't
- be tracked either. This helps reduce the cost of each
- garbage collection by decreasing the number of objects to be
- considered and traversed by the collector.
- (Contributed by Antoine Pitrou; :issue:`4688`.)
-
-* 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
- benchmark results on 32-bit machines have been mixed. Therefore,
- the default is to use base 2**30 on 64-bit machines and base 2**15
- on 32-bit machines; on Unix, there's a new configure option
- :option:`--enable-big-digits` that can be used to override this default.
-
- Apart from the performance improvements this change should be
- invisible to end users, with one exception: for testing and
- debugging purposes there's a new structseq :data:`sys.long_info` that
- provides information about the internal format, giving the number of
- bits per digit and the size in bytes of the C type used to store
- each digit::
-
- >>> import sys
- >>> sys.long_info
- sys.long_info(bits_per_digit=30, sizeof_digit=4)
-
- (Contributed by Mark Dickinson; :issue:`4258`.)
-
- Another set of changes made long objects a few bytes smaller: 2 bytes
- smaller on 32-bit systems and 6 bytes on 64-bit.
- (Contributed by Mark Dickinson; :issue:`5260`.)
-
-* The division algorithm for long integers has been made faster
- by tightening the inner loop, doing shifts instead of multiplications,
- and fixing an unnecessary extra iteration.
- Various benchmarks show speedups of between 50% and 150% for long
- integer divisions and modulo operations.
- (Contributed by Mark Dickinson; :issue:`5512`.)
- Bitwise operations are also significantly faster (initial patch by
- Gregory Smith; :issue:`1087418`).
-
-* The implementation of ``%`` checks for the left-side operand being
- a Python string and special-cases it; this results in a 1-3%
- performance increase for applications that frequently use ``%``
- with strings, such as templating libraries.
- (Implemented by Collin Winter; :issue:`5176`.)
-
-* List comprehensions with an ``if`` condition are compiled into
- faster bytecode. (Patch by Antoine Pitrou, back-ported to 2.7
- by Jeffrey Yasskin; :issue:`4715`.)
-
-* 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`.)
-
-* The :meth:`split`, :meth:`replace`, :meth:`rindex`,
- :meth:`rpartition`, and :meth:`rsplit` methods of string-like types
- (strings, Unicode strings, and :class:`bytearray` objects) now use a
- fast reverse-search algorithm instead of a character-by-character
- scan. This is sometimes faster by a factor of 10. (Added by
- Florent Xicluna; :issue:`7462` and :issue:`7622`.)
-
-* 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`.)
-
-.. ======================================================================
-
-New and Improved Modules
-========================
-
-As in every release, Python's standard library received a number of
-enhancements and bug fixes. Here's a partial list of the most notable
-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.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:`binascii` module now supports the buffer API, so it can be
- used with :class:`memoryview` instances and other similar buffer objects.
- (Backported from 3.x by Florent Xicluna; :issue:`7703`.)
-
-* Updated module: the :mod:`bsddb` module has been updated from 4.7.2devel9
- to version 4.8.4 of
- `the pybsddb package <http://www.jcea.es/programacion/pybsddb.htm>`__.
- The new version features better Python 3.x compatibility, various bug fixes,
- and adds several new BerkeleyDB flags and methods.
- (Updated by Jesús Cea Avión; :issue:`8156`. The pybsddb
- changelog can be read at http://hg.jcea.es/pybsddb/file/tip/ChangeLog.)
-
-* The :mod:`bz2` module's :class:`~bz2.BZ2File` now supports the context
- management protocol, so you can write ``with bz2.BZ2File(...) as f:``.
- (Contributed by Hagen Fürstenau; :issue:`3860`.)
-
-* New class: the :class:`~collections.Counter` class in the :mod:`collections`
- module is useful for tallying data. :class:`~collections.Counter` instances
- behave mostly like dictionaries but return zero for missing keys instead of
- raising a :exc:`KeyError`:
-
- .. doctest::
- :options: +NORMALIZE_WHITESPACE
-
- >>> from collections import Counter
- >>> c = Counter()
- >>> for letter in 'here is a sample of english text':
- ... c[letter] += 1
- ...
- >>> c
- Counter({' ': 6, 'e': 5, 's': 3, 'a': 2, 'i': 2, 'h': 2,
- 'l': 2, 't': 2, 'g': 1, 'f': 1, 'm': 1, 'o': 1, 'n': 1,
- 'p': 1, 'r': 1, 'x': 1})
- >>> c['e']
- 5
- >>> c['z']
- 0
-
- There are three additional :class:`~collections.Counter` methods.
- :meth:`~collections.Counter.most_common` returns the N most common
- elements and their counts. :meth:`~collections.Counter.elements`
- returns an iterator over the contained elements, repeating each
- element as many times as its count.
- :meth:`~collections.Counter.subtract` takes an iterable and
- subtracts one for each element instead of adding; if the argument is
- a dictionary or another :class:`Counter`, the counts are
- subtracted. ::
-
- >>> c.most_common(5)
- [(' ', 6), ('e', 5), ('s', 3), ('a', 2), ('i', 2)]
- >>> c.elements() ->
- 'a', 'a', ' ', ' ', ' ', ' ', ' ', ' ',
- 'e', 'e', 'e', 'e', 'e', 'g', 'f', 'i', 'i',
- 'h', 'h', 'm', 'l', 'l', 'o', 'n', 'p', 's',
- 's', 's', 'r', 't', 't', 'x'
- >>> c['e']
- 5
- >>> c.subtract('very heavy on the letter e')
- >>> c['e'] # Count is now lower
- -1
-
- Contributed by Raymond Hettinger; :issue:`1696199`.
-
- .. revision 79660
-
- New class: :class:`~collections.OrderedDict` is described in the earlier
- section :ref:`pep-0372`.
-
- New method: The :class:`~collections.deque` data type now has a
- :meth:`~collections.deque.count` method that returns the number of
- contained elements equal to the supplied argument *x*, and a
- :meth:`~collections.deque.reverse` method that reverses the elements
- of the deque in-place. :class:`deque` also exposes its maximum
- length as the read-only :attr:`~collections.deque.maxlen` attribute.
- (Both features added by Raymond Hettinger.)
-
- The :class:`~collections.namedtuple` class now has an optional *rename* parameter.
- If *rename* is true, field names that are invalid because they've
- been repeated or aren't legal Python identifiers will be
- renamed to legal names that are derived from the field's
- position within the list of fields:
-
- >>> from collections import namedtuple
- >>> T = namedtuple('T', ['field1', '$illegal', 'for', 'field2'], rename=True)
- >>> T._fields
- ('field1', '_1', '_2', 'field2')
-
- (Added by Raymond Hettinger; :issue:`1818`.)
-
- Finally, the :class:`~collections.Mapping` abstract base class now
- returns :const:`NotImplemented` if a mapping is compared to
- another type that isn't a :class:`Mapping`.
- (Fixed by Daniel Stutzbach; :issue:`8729`.)
-
-* Constructors for the parsing classes in the :mod:`ConfigParser` module now
- take a *allow_no_value* parameter, defaulting to false; if true,
- options without values will be allowed. For example::
-
- >>> import ConfigParser, StringIO
- >>> sample_config = """
- ... [mysqld]
- ... user = mysql
- ... pid-file = /var/run/mysqld/mysqld.pid
- ... skip-bdb
- ... """
- >>> config = ConfigParser.RawConfigParser(allow_no_value=True)
- >>> config.readfp(StringIO.StringIO(sample_config))
- >>> config.get('mysqld', 'user')
- 'mysql'
- >>> print config.get('mysqld', 'skip-bdb')
- None
- >>> print config.get('mysqld', 'unknown')
- Traceback (most recent call last):
- ...
- NoOptionError: No option 'unknown' in section: 'mysqld'
-
- (Contributed by Mats Kindahl; :issue:`7005`.)
-
-* Deprecated function: :func:`contextlib.nested`, which allows
- handling more than one context manager with a single :keyword:`with`
- statement, has been deprecated, because the :keyword:`with` statement
- now supports multiple context managers.
-
-* The :mod:`cookielib` module now ignores cookies that have an invalid
- version field, one that doesn't contain an integer value. (Fixed by
- John J. Lee; :issue:`3924`.)
-
-* The :mod:`copy` module's :func:`~copy.deepcopy` function will now
- correctly copy bound instance methods. (Implemented by
- Robert Collins; :issue:`1515`.)
-
-* The :mod:`ctypes` module now always converts ``None`` to a C NULL
- pointer for arguments declared as pointers. (Changed by Thomas
- Heller; :issue:`4606`.) The underlying `libffi library
- <http://sourceware.org/libffi/>`__ has been updated to version
- 3.0.9, containing various fixes for different platforms. (Updated
- by Matthias Klose; :issue:`8142`.)
-
-* New method: the :mod:`datetime` module's :class:`~datetime.timedelta` class
- gained a :meth:`~datetime.timedelta.total_seconds` method that returns the
- number of seconds in the duration. (Contributed by Brian Quinlan; :issue:`5788`.)
-
-* New method: the :class:`~decimal.Decimal` class gained a
- :meth:`~decimal.Decimal.from_float` class method that performs an exact
- conversion of a floating-point number to a :class:`~decimal.Decimal`.
- This exact conversion 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`.)
-
- Comparing instances of :class:`Decimal` with floating-point
- numbers now produces sensible results based on the numeric values
- of the operands. Previously such comparisons would fall back to
- Python's default rules for comparing objects, which produced arbitrary
- results based on their type. Note that you still cannot combine
- :class:`Decimal` and floating-point in other operations such as addition,
- since you should be explicitly choosing how to convert between float and
- :class:`Decimal`.
- (Fixed by Mark Dickinson; :issue:`2531`.)
-
- The constructor for :class:`~decimal.Decimal` now accepts
- floating-point numbers (added by Raymond Hettinger; :issue:`8257`)
- and non-European Unicode characters such as Arabic-Indic digits
- (contributed by Mark Dickinson; :issue:`6595`).
-
- Most of the methods of the :class:`~decimal.Context` class now accept integers
- as well as :class:`~decimal.Decimal` instances; the only exceptions are the
- :meth:`~decimal.Context.canonical` and :meth:`~decimal.Context.is_canonical`
- methods. (Patch by Juan José Conti; :issue:`7633`.)
-
- When using :class:`~decimal.Decimal` instances with a string's
- :meth:`~str.format` method, the default alignment was previously
- left-alignment. This has been changed to right-alignment, which is
- more sensible for numeric types. (Changed by Mark Dickinson; :issue:`6857`.)
-
- Comparisons involving a signaling NaN value (or ``sNAN``) now signal
- :const:`InvalidOperation` instead of silently returning a true or
- false value depending on the comparison operator. Quiet NaN values
- (or ``NaN``) are now hashable. (Fixed by Mark Dickinson;
- :issue:`7279`.)
-
-* The :mod:`difflib` module now produces output that is more
- compatible with modern :command:`diff`/:command:`patch` tools
- through one small change, using a tab character instead of spaces as
- a separator in the header giving the filename. (Fixed by Anatoly
- Techtonik; :issue:`7585`.)
-
-* The Distutils ``sdist`` command now always regenerates the
- :file:`MANIFEST` file, since even if the :file:`MANIFEST.in` or
- :file:`setup.py` files haven't been modified, the user might have
- created some new files that should be included.
- (Fixed by Tarek Ziadé; :issue:`8688`.)
-
-* The :mod:`doctest` module's :const:`IGNORE_EXCEPTION_DETAIL` flag
- will now ignore the name of the module containing the exception
- being tested. (Patch by Lennart Regebro; :issue:`7490`.)
-
-* The :mod:`email` module's :class:`~email.message.Message` class will
- now accept a Unicode-valued payload, automatically converting the
- payload to the encoding specified by :attr:`output_charset`.
- (Added by R. David Murray; :issue:`1368247`.)
-
-* The :class:`~fractions.Fraction` class now accepts a single float or
- :class:`~decimal.Decimal` instance, or two rational numbers, as
- arguments to its constructor. (Implemented by Mark Dickinson;
- rationals added in :issue:`5812`, and float/decimal in
- :issue:`8294`.)
-
- Ordering comparisons (``<``, ``<=``, ``>``, ``>=``) between
- fractions and complex numbers now raise a :exc:`TypeError`.
- This fixes an oversight, making the :class:`Fraction` match the other
- numeric types.
-
- .. revision 79455
-
-* New class: :class:`~ftplib.FTP_TLS` in
- the :mod:`ftplib` module provides secure FTP
- connections using TLS encapsulation of authentication as well as
- subsequent control and data transfers.
- (Contributed by Giampaolo Rodola; :issue:`2054`.)
-
- The :meth:`~ftplib.FTP.storbinary` method for binary uploads can now restart
- uploads thanks to an added *rest* parameter (patch by Pablo Mouzo;
- :issue:`6845`.)
-
-* New class decorator: :func:`total_ordering` in the :mod:`functools`
- module takes a class that defines an :meth:`__eq__` method and one of
- :meth:`__lt__`, :meth:`__le__`, :meth:`__gt__`, or :meth:`__ge__`,
- and generates the missing comparison methods. Since the
- :meth:`__cmp__` method is being deprecated in Python 3.x,
- this decorator makes it easier to define ordered classes.
- (Added by Raymond Hettinger; :issue:`5479`.)
-
- New function: :func:`cmp_to_key` will take an old-style comparison
- function that expects two arguments and return a new callable that
- can be used as the *key* parameter to functions such as
- :func:`sorted`, :func:`min` and :func:`max`, etc. The primary
- intended use is to help with making code compatible with Python 3.x.
- (Added by Raymond Hettinger.)
-
-* New function: the :mod:`gc` module's :func:`~gc.is_tracked` returns
- true if a given instance is tracked by the garbage collector, false
- otherwise. (Contributed by Antoine Pitrou; :issue:`4688`.)
-
-* The :mod:`gzip` module's :class:`~gzip.GzipFile` now supports the context
- management protocol, so you can write ``with gzip.GzipFile(...) as f:``
- (contributed by Hagen Fürstenau; :issue:`3860`), and it now implements
- the :class:`io.BufferedIOBase` ABC, so you can wrap it with
- :class:`io.BufferedReader` for faster processing
- (contributed by Nir Aides; :issue:`7471`).
- It's also now possible to override the modification time
- recorded in a gzipped file by providing an optional timestamp to
- the constructor. (Contributed by Jacques Frechet; :issue:`4272`.)
-
- Files in gzip format can be padded with trailing zero bytes; the
- :mod:`gzip` module will now consume these trailing bytes. (Fixed by
- Tadek Pietraszek and Brian Curtin; :issue:`2846`.)
-
-* New attribute: the :mod:`hashlib` module now has an :attr:`~hashlib.hashlib.algorithms`
- attribute containing a tuple naming the supported algorithms.
- In Python 2.7, ``hashlib.algorithms`` contains
- ``('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512')``.
- (Contributed by Carl Chenet; :issue:`7418`.)
-
-* The default :class:`~httplib.HTTPResponse` class used by the :mod:`httplib` module now
- supports buffering, resulting in much faster reading of HTTP responses.
- (Contributed by Kristján Valur Jónsson; :issue:`4879`.)
-
- The :class:`~httplib.HTTPConnection` and :class:`~httplib.HTTPSConnection` classes
- now support a *source_address* parameter, a ``(host, port)`` 2-tuple
- giving the source address that will be used for the connection.
- (Contributed by Eldon Ziegler; :issue:`3972`.)
-
-* The :mod:`ihooks` module now supports relative imports. Note that
- :mod:`ihooks` is an older module for customizing imports,
- superseded by the :mod:`imputil` module added in Python 2.0.
- (Relative import support added by Neil Schemenauer.)
-
- .. revision 75423
-
-* The :mod:`imaplib` module now supports IPv6 addresses.
- (Contributed by Derek Morr; :issue:`1655`.)
-
-* New function: the :mod:`inspect` module's :func:`~inspect.getcallargs`
- takes a callable and its positional and keyword arguments,
- and figures out which of the callable's parameters will receive each argument,
- returning a dictionary mapping argument names to their values. For example::
-
- >>> from inspect import getcallargs
- >>> def f(a, b=1, *pos, **named):
- ... pass
- >>> getcallargs(f, 1, 2, 3)
- {'a': 1, 'b': 2, 'pos': (3,), 'named': {}}
- >>> getcallargs(f, a=2, x=4)
- {'a': 2, 'b': 1, 'pos': (), 'named': {'x': 4}}
- >>> getcallargs(f)
- Traceback (most recent call last):
- ...
- TypeError: f() takes at least 1 argument (0 given)
-
- Contributed by George Sakkis; :issue:`3135`.
-
-* Updated module: 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 being performed. 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`.) The :meth:`~io.IOBase.truncate` method now preserves the
- file position; previously it would change the file position to the
- end of the new file. (Fixed by Pascal Chambon; :issue:`6939`.)
-
-* New function: ``itertools.compress(data, selectors)`` takes two
- iterators. Elements of *data* are returned if the corresponding
- value in *selectors* is true::
-
- itertools.compress('ABCDEF', [1,0,1,0,1,1]) =>
- A, C, E, F
-
- .. maybe here is better to use >>> list(itertools.compress(...)) instead
-
- New function: ``itertools.combinations_with_replacement(iter, r)``
- returns all the possible *r*-length combinations of elements from the
- iterable *iter*. Unlike :func:`~itertools.combinations`, individual elements
- can be repeated in the generated combinations::
-
- itertools.combinations_with_replacement('abc', 2) =>
- ('a', 'a'), ('a', 'b'), ('a', 'c'),
- ('b', 'b'), ('b', 'c'), ('c', 'c')
-
- Note that elements are treated as unique depending on their position
- in the input, not their actual values.
-
- The :func:`itertools.count` function now has a *step* argument that
- allows incrementing by values other than 1. :func:`~itertools.count` also
- now allows keyword arguments, and using non-integer values such as
- floats or :class:`~decimal.Decimal` instances. (Implemented by Raymond
- Hettinger; :issue:`5032`.)
-
- :func:`itertools.combinations` and :func:`itertools.product`
- previously raised :exc:`ValueError` for values of *r* larger than
- the input iterable. This was deemed a specification error, so they
- now return an empty iterator. (Fixed by Raymond Hettinger; :issue:`4816`.)
-
-* Updated module: The :mod:`json` module was upgraded to version 2.0.9 of the
- simplejson package, which includes a C extension that makes
- encoding and decoding faster.
- (Contributed by Bob Ippolito; :issue:`4136`.)
-
- To support the new :class:`collections.OrderedDict` type, :func:`json.load`
- now has an optional *object_pairs_hook* parameter that will be called
- with any object literal that decodes to a list of pairs.
- (Contributed by Raymond Hettinger; :issue:`5381`.)
-
-* The :mod:`mailbox` module's :class:`Maildir` class now records the
- timestamp on the directories it reads, and only re-reads them if the
- modification time has subsequently changed. This improves
- performance by avoiding unneeded directory scans. (Fixed by
- A.M. Kuchling and Antoine Pitrou; :issue:`1607951`, :issue:`6896`.)
-
-* New functions: the :mod:`math` module gained
- :func:`~math.erf` and :func:`~math.erfc` for the error function and the complementary error function,
- :func:`~math.expm1` which computes ``e**x - 1`` with more precision than
- using :func:`~math.exp` and subtracting 1,
- :func:`~math.gamma` for the Gamma function, and
- :func:`~math.lgamma` for the natural log of the 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 :class:`~multiprocessing.Pool` class, which controls a pool of worker processes,
- now has an optional *maxtasksperchild* parameter. Worker processes
- will perform the specified number of tasks and then exit, causing the
- :class:`~multiprocessing.Pool` to start a new worker. This is useful if tasks may leak
- memory or other resources, or if some tasks will cause the worker to
- become very large.
- (Contributed by Charles Cazabon; :issue:`6963`.)
-
-* The :mod:`nntplib` module now supports IPv6 addresses.
- (Contributed by Derek Morr; :issue:`1664`.)
-
-* New functions: the :mod:`os` module wraps the following POSIX system
- calls: :func:`~os.getresgid` and :func:`~os.getresuid`, which return the
- real, effective, and saved GIDs and UIDs;
- :func:`~os.setresgid` and :func:`~os.setresuid`, which set
- real, effective, and saved GIDs and UIDs to new values;
- :func:`~os.initgroups`, which initialize the group access list
- for the current process. (GID/UID functions
- contributed by Travis H.; :issue:`6508`. Support for initgroups added
- by Jean-Paul Calderone; :issue:`7333`.)
-
- The :func:`os.fork` function now re-initializes the import lock in
- the child process; this fixes problems on Solaris when :func:`~os.fork`
- is called from a thread. (Fixed by Zsolt Cserna; :issue:`7242`.)
-
-* In the :mod:`os.path` module, the :func:`~os.path.normpath` and
- :func:`~os.path.abspath` functions now preserve Unicode; if their input path
- is a Unicode string, the return value is also a Unicode string.
- (:meth:`~os.path.normpath` fixed by Matt Giuca in :issue:`5827`;
- :meth:`~os.path.abspath` fixed by Ezio Melotti in :issue:`3426`.)
-
-* 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`.)
-
-* The :mod:`re` module's :func:`~re.split`, :func:`~re.sub`, and :func:`~re.subn`
- now accept an optional *flags* argument, for consistency with the
- other functions in the module. (Added by Gregory P. Smith.)
-
-* New function: :func:`~runpy.run_path` in the :mod:`runpy` module
- will execute the code at a provided *path* argument. *path* can be
- the path of a Python source file (:file:`example.py`), a compiled
- bytecode file (:file:`example.pyc`), a directory
- (:file:`./package/`), or a zip archive (:file:`example.zip`). If a
- directory or zip path is provided, it will be added to the front of
- ``sys.path`` and the module :mod:`__main__` will be imported. It's
- expected that the directory or zip contains a :file:`__main__.py`;
- if it doesn't, some other :file:`__main__.py` might be imported from
- a location later in ``sys.path``. This makes more of the machinery
- of :mod:`runpy` available to scripts that want to mimic the way
- Python's command line processes an explicit path name.
- (Added by Nick Coghlan; :issue:`6816`.)
-
-* New function: in the :mod:`shutil` module, :func:`~shutil.make_archive`
- takes a filename, archive type (zip or tar-format), and a directory
- path, and creates an archive containing the directory's contents.
- (Added by Tarek Ziadé.)
-
- :mod:`shutil`'s :func:`~shutil.copyfile` and :func:`~shutil.copytree`
- functions now raise a :exc:`~shutil.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`.)
-
-* The :mod:`signal` module no longer re-installs the signal handler
- unless this is truly necessary, which fixes a bug that could make it
- impossible to catch the EINTR signal robustly. (Fixed by
- Charles-Francois Natali; :issue:`8354`.)
-
-* New functions: in the :mod:`site` module, three new functions
- return various site- and user-specific paths.
- :func:`~site.getsitepackages` returns a list containing all
- global site-packages directories,
- :func:`~site.getusersitepackages` returns the path of the user's
- site-packages directory, and
- :func:`~site.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 Ziadé; :issue:`6693`.)
-
- The :mod:`site` module now reports exceptions occurring
- when the :mod:`sitecustomize` module is imported, and will no longer
- catch and swallow the :exc:`KeyboardInterrupt` exception. (Fixed by
- Victor Stinner; :issue:`3137`.)
-
-* The :func:`~socket.create_connection` function
- gained a *source_address* parameter, a ``(host, port)`` 2-tuple
- giving the source address that will be used for the connection.
- (Contributed by Eldon Ziegler; :issue:`3972`.)
-
- The :meth:`~socket.socket.recv_into` and :meth:`~socket.socket.recvfrom_into`
- methods will now write into objects that support the buffer API, most usefully
- the :class:`bytearray` and :class:`memoryview` objects. (Implemented by
- Antoine Pitrou; :issue:`8104`.)
-
-* The :mod:`SocketServer` module's :class:`~SocketServer.TCPServer` class now
- supports socket timeouts and disabling the Nagle algorithm.
- The :attr:`~SocketServer.TCPServer.disable_nagle_algorithm` class attribute
- defaults to 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.
- The :attr:`~SocketServer.TCPServer.timeout` class attribute can hold
- a timeout in seconds that will be applied to the request socket; if
- no request is received within that time, :meth:`handle_timeout`
- will be called and :meth:`handle_request` will return.
- (Contributed by Kristján Valur Jónsson; :issue:`6192` and :issue:`6267`.)
-
-* Updated module: the :mod:`sqlite3` module has been updated to
- version 2.6.0 of the `pysqlite package <http://code.google.com/p/pysqlite/>`__. Version 2.6.0 includes a number of bugfixes, and adds
- the ability to load SQLite extensions from shared libraries.
- Call the ``enable_load_extension(True)`` method to enable extensions,
- and then call :meth:`~sqlite3.Connection.load_extension` to load a particular shared library.
- (Updated by Gerhard Häring.)
-
-* The :mod:`ssl` module's :class:`ssl.SSLSocket` objects now support the
- buffer API, which fixed a test suite failure (fix by Antoine Pitrou;
- :issue:`7133`) and automatically set
- OpenSSL's :cmacro:`SSL_MODE_AUTO_RETRY`, which will prevent an error
- code being returned from :meth:`recv` operations that trigger an SSL
- renegotiation (fix by Antoine Pitrou; :issue:`8222`).
-
- The :func:`ssl.wrap_socket` constructor function now takes a
- *ciphers* argument that's a string listing the encryption algorithms
- to be allowed; the format of the string is described
- `in the OpenSSL documentation
- <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`__.
- (Added by Antoine Pitrou; :issue:`8322`.)
-
- Another change makes the extension load all of OpenSSL's ciphers and
- digest algorithms so that they're all available. Some SSL
- certificates couldn't be verified, reporting an "unknown algorithm"
- error. (Reported by Beda Kosata, and fixed by Antoine Pitrou;
- :issue:`8484`.)
-
- The version of OpenSSL being used is now available as the module
- attributes :data:`ssl.OPENSSL_VERSION` (a string),
- :data:`ssl.OPENSSL_VERSION_INFO` (a 5-tuple), and
- :data:`ssl.OPENSSL_VERSION_NUMBER` (an integer). (Added by Antoine
- Pitrou; :issue:`8321`.)
-
-* 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`.) The :func:`~struct.pack` function will also
- attempt to use :meth:`__index__` to convert and pack non-integers
- before trying the :meth:`__int__` method or reporting an error.
- (Changed by Mark Dickinson; :issue:`8300`.)
-
-* New function: the :mod:`subprocess` module's
- :func:`~subprocess.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
- error, or raises a :exc:`~subprocess.CalledProcessError` exception otherwise.
-
- ::
-
- >>> subprocess.check_output(['df', '-h', '.'])
- 'Filesystem Size Used Avail Capacity Mounted on\n
- /dev/disk0s2 52G 49G 3.0G 94% /\n'
-
- >>> subprocess.check_output(['df', '-h', '/bogus'])
- ...
- subprocess.CalledProcessError: Command '['df', '-h', '/bogus']' returned non-zero exit status 1
-
- (Contributed by Gregory P. Smith.)
-
- The :mod:`subprocess` module will now retry its internal system calls
- on receiving an :const:`EINTR` signal. (Reported by several people; final
- patch by Gregory P. Smith in :issue:`1068268`.)
-
-* New function: :func:`~symtable.is_declared_global` in the :mod:`symtable` module
- returns true for variables that are explicitly declared to be global,
- false for ones that are implicitly global.
- (Contributed by Jeremy Hylton.)
-
-* The :mod:`syslog` module will now use the value of ``sys.argv[0]`` as the
- identifier instead of the previous default value of ``'python'``.
- (Changed by Sean Reifschneider; :issue:`8451`.)
-
-* The ``sys.version_info`` value is now a named tuple, with attributes
- named :attr:`major`, :attr:`minor`, :attr:`micro`,
- :attr:`releaselevel`, and :attr:`serial`. (Contributed by Ross
- Light; :issue:`4285`.)
-
- :func:`sys.getwindowsversion` also returns a named tuple,
- with attributes named :attr:`major`, :attr:`minor`, :attr:`build`,
- :attr:`platform`, :attr:`service_pack`, :attr:`service_pack_major`,
- :attr:`service_pack_minor`, :attr:`suite_mask`, and
- :attr:`product_type`. (Contributed by Brian Curtin; :issue:`7766`.)
-
-* The :mod:`tarfile` module's default error handling has changed, to
- no longer suppress fatal errors. The default error level was previously 0,
- which meant that errors would only result in a message being written to the
- debug log, but because the debug log is not activated by default,
- these errors go unnoticed. The default error level is now 1,
- which raises an exception if there's an error.
- (Changed by Lars Gustäbel; :issue:`7357`.)
-
- :mod:`tarfile` now supports filtering the :class:`~tarfile.TarInfo`
- objects being added to a tar file. When you call :meth:`~tarfile.TarFile.add`,
- you may supply an optional *filter* argument
- that's a callable. The *filter* callable will be passed the
- :class:`~tarfile.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 Gustäbel; :issue:`6856`.)
- The :class:`~tarfile.TarFile` class also now supports the context manager protocol.
- (Added by Lars Gustäbel; :issue:`7232`.)
-
-* The :meth:`~threading.Event.wait` method of the :class:`threading.Event` class
- now returns the internal flag on exit. This means the method will usually
- return true because :meth:`~threading.Event.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 Tim Lesher; :issue:`1674032`.)
-
-* The Unicode database provided by the :mod:`unicodedata` module is
- now used internally to determine which characters are numeric,
- whitespace, or represent line breaks. The database also
- includes information from the :file:`Unihan.txt` data file (patch
- by Anders Chrigström and Amaury Forgeot d'Arc; :issue:`1571184`)
- and has been updated to version 5.2.0 (updated by
- Florent Xicluna; :issue:`8024`).
-
-* The :mod:`urlparse` module's :func:`~urlparse.urlsplit` now handles
- unknown URL schemes in a fashion compliant with :rfc:`3986`: if the
- URL is of the form ``"<something>://..."``, the text before the
- ``://`` is treated as the scheme, even if it's a made-up scheme that
- the module doesn't know about. This change may break code that
- worked around the old behaviour. For example, Python 2.6.4 or 2.5
- will return the following:
-
- >>> import urlparse
- >>> urlparse.urlsplit('invented://host/filename?query')
- ('invented', '', '//host/filename?query', '', '')
-
- Python 2.7 (and Python 2.6.5) will return:
-
- >>> import urlparse
- >>> urlparse.urlsplit('invented://host/filename?query')
- ('invented', 'host', '/filename?query', '', '')
-
- (Python 2.7 actually produces slightly different output, since it
- returns a named tuple instead of a standard tuple.)
-
- The :mod:`urlparse` module also supports IPv6 literal addresses as defined by
- :rfc:`2732` (contributed by Senthil Kumaran; :issue:`2987`). ::
-
- >>> urlparse.urlparse('http://[1080::8:800:200C:417A]/foo')
- ParseResult(scheme='http', netloc='[1080::8:800:200C:417A]',
- path='/foo', params='', query='', fragment='')
-
-* New class: the :class:`~weakref.WeakSet` class in the :mod:`weakref`
- module is a set that only holds weak references to its elements; elements
- will be removed once there are no references pointing to them.
- (Originally implemented in Python 3.x by Raymond Hettinger, and backported
- to 2.7 by Michael Foord.)
-
-* The ElementTree library, :mod:`xml.etree`, no longer escapes
- ampersands and angle brackets when outputting an XML processing
- instruction (which looks like ``<?xml-stylesheet href="#style1"?>``)
- or comment (which looks like ``<!-- comment -->``).
- (Patch by Neil Muller; :issue:`2746`.)
-
-* The XML-RPC client and server, provided by the :mod:`xmlrpclib` and
- :mod:`SimpleXMLRPCServer` modules, have improved performance by
- supporting HTTP/1.1 keep-alive and by optionally using gzip encoding
- to compress the XML being exchanged. The gzip compression is
- controlled by the :attr:`encode_threshold` attribute of
- :class:`SimpleXMLRPCRequestHandler`, which contains a size in bytes;
- responses larger than this will be compressed.
- (Contributed by Kristján Valur Jónsson; :issue:`6267`.)
-
-* The :mod:`zipfile` module's :class:`~zipfile.ZipFile` now supports the context
- management protocol, so you can write ``with zipfile.ZipFile(...) as f:``.
- (Contributed by Brian Curtin; :issue:`5511`.)
-
- :mod:`zipfile` now also supports archiving empty directories and
- extracts them correctly. (Fixed by Kuba Wieczorek; :issue:`4710`.)
- Reading files out of an archive is faster, and interleaving
- :meth:`~zipfile.ZipFile.read` and :meth:`~zipfile.ZipFile.readline` now works correctly.
- (Contributed by Nir Aides; :issue:`7610`.)
-
- The :func:`~zipfile.is_zipfile` function now
- accepts a file object, in addition to the path names accepted in earlier
- versions. (Contributed by Gabriel Genellina; :issue:`4756`.)
-
- The :meth:`~zipfile.ZipFile.writestr` method now has an optional *compress_type* parameter
- that lets you override the default compression method specified in the
- :class:`~zipfile.ZipFile` constructor. (Contributed by Ronald Oussoren;
- :issue:`6003`.)
-
-
-.. ======================================================================
-.. whole new modules get described in subsections here
-
-
-.. _importlib-section:
-
-New module: importlib
-------------------------------
-
-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 users 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:`~importlib.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:`~importlib.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
- >>> file_util = import_module('..file_util', 'distutils.command')
- >>> file_util
- <module 'distutils.file_util' from '/python/Lib/distutils/file_util.pyc'>
-
-:mod:`importlib` was implemented by Brett Cannon and introduced in
-Python 3.1.
-
-
-New module: sysconfig
----------------------------------
-
-The :mod:`sysconfig` module has been pulled out of the Distutils
-package, becoming a new top-level module in its own right.
-:mod:`sysconfig` provides functions for getting information about
-Python's build process: compiler switches, installation paths, the
-platform name, and whether Python is running from its source
-directory.
-
-Some of the functions in the module are:
-
-* :func:`~sysconfig.get_config_var` returns variables from Python's
- Makefile and the :file:`pyconfig.h` file.
-* :func:`~sysconfig.get_config_vars` returns a dictionary containing
- all of the configuration variables.
-* :func:`~sysconfig.getpath` returns the configured path for
- a particular type of module: the standard library,
- site-specific modules, platform-specific modules, etc.
-* :func:`~sysconfig.is_python_build` returns true if you're running a
- binary from a Python source tree, and false otherwise.
-
-Consult the :mod:`sysconfig` documentation for more details and for
-a complete list of functions.
-
-The Distutils package and :mod:`sysconfig` are now maintained by Tarek
-Ziadé, who has also started a Distutils2 package (source repository at
-http://hg.python.org/distutils2/) for developing a next-generation
-version of Distutils.
-
-
-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.
-
-To learn more, read the :mod:`ttk` module documentation. You may also
-wish to read the Tcl/Tk manual page describing the
-Ttk theme engine, available at
-http://www.tcl.tk/man/tcl8.5/TkCmd/ttk_intro.htm. Some
-screenshots of the Python/Ttk code in use are at
-http://code.google.com/p/python-ttk/wiki/Screenshots.
-
-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.
-
-
-.. _unittest-section:
-
-Updated module: unittest
----------------------------------
-
-The :mod:`unittest` module was greatly enhanced; many
-new features were added. Most of these features were implemented
-by Michael Foord, unless otherwise noted. The enhanced version of
-the module is downloadable separately for use with Python versions 2.4 to 2.6,
-packaged as the :mod:`unittest2` package, from
-http://pypi.python.org/pypi/unittest2.
-
-When used from the command line, the module can automatically discover
-tests. It's not as fancy as `py.test <http://pytest.org>`__ or
-`nose <http://code.google.com/p/python-nose/>`__, but provides a simple way
-to run tests kept within a set of package directories. For example,
-the following command will search the :file:`test/` subdirectory for
-any importable test files named ``test*.py``::
-
- python -m unittest discover -s test
-
-Consult the :mod:`unittest` module documentation for more details.
-(Developed in :issue:`6001`.)
-
-The :func:`main` function supports some other new options:
-
-* :option:`-b` or :option:`--buffer` will buffer the standard output
- and standard error streams during each test. If the test passes,
- any resulting output will be discarded; on failure, the buffered
- output will be displayed.
-
-* :option:`-c` or :option:`--catch` will cause the control-C interrupt
- to be handled more gracefully. Instead of interrupting the test
- process immediately, the currently running test will be completed
- and then the partial results up to the interruption will be reported.
- If you're impatient, a second press of control-C will cause an immediate
- interruption.
-
- This control-C handler tries to avoid causing problems when the code
- being tested or the tests being run have defined a signal handler of
- their own, by noticing that a signal handler was already set and
- calling it. If this doesn't work for you, there's a
- :func:`removeHandler` decorator that can be used to mark tests that
- should have the control-C handling disabled.
-
-* :option:`-f` or :option:`--failfast` makes
- test execution stop immediately when a test fails instead of
- continuing to execute further tests. (Suggested by Cliff Dyer and
- implemented by Michael Foord; :issue:`8074`.)
-
-The progress messages 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:`~unittest.SkipTest` exception to skip a
-test (:issue:`1034053`).
-
-The error messages for :meth:`~unittest.TestCase.assertEqual`,
-:meth:`~unittest.TestCase.assertTrue`, and :meth:`~unittest.TestCase.assertFalse`
-failures now provide more information. If you set the
-:attr:`~unittest.TestCase.longMessage` attribute of your :class:`~unittest.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:`~unittest.TestCase.assertRaises` method now
-returns a context handler when called without providing a callable
-object to run. For example, you can write this::
-
- with self.assertRaises(KeyError):
- {}['foo']
-
-(Implemented by Antoine Pitrou; :issue:`4444`.)
-
-.. rev 78774
-
-Module- and class-level setup and teardown fixtures are now supported.
-Modules can contain :func:`~unittest.setUpModule` and :func:`~unittest.tearDownModule`
-functions. Classes can have :meth:`~unittest.TestCase.setUpClass` and
-:meth:`~unittest.TestCase.tearDownClass` methods that must be defined as class methods
-(using ``@classmethod`` or equivalent). These functions and
-methods are invoked when the test runner switches to a test case in a
-different module or class.
-
-The methods :meth:`~unittest.TestCase.addCleanup` and
-:meth:`~unittest.TestCase.doCleanups` were added.
-:meth:`~unittest.TestCase.addCleanup` lets you add cleanup functions that
-will be called unconditionally (after :meth:`~unittest.TestCase.setUp` if
-:meth:`~unittest.TestCase.setUp` fails, otherwise after :meth:`~unittest.TestCase.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:`~unittest.TestCase.assertIsNone` and :meth:`~unittest.TestCase.assertIsNotNone` take one
- expression and verify that the result is or is not ``None``.
-
-* :meth:`~unittest.TestCase.assertIs` and :meth:`~unittest.TestCase.assertIsNot`
- take two values and check whether the two values evaluate to the same object or not.
- (Added by Michael Foord; :issue:`2578`.)
-
-* :meth:`~unittest.TestCase.assertIsInstance` and
- :meth:`~unittest.TestCase.assertNotIsInstance` check whether
- the resulting object is an instance of a particular class, or of
- one of a tuple of classes. (Added by Georg Brandl; :issue:`7031`.)
-
-* :meth:`~unittest.TestCase.assertGreater`, :meth:`~unittest.TestCase.assertGreaterEqual`,
- :meth:`~unittest.TestCase.assertLess`, and :meth:`~unittest.TestCase.assertLessEqual` compare
- two quantities.
-
-* :meth:`~unittest.TestCase.assertMultiLineEqual` compares two strings, and if they're
- not equal, displays a helpful comparison that highlights the
- differences in the two strings. This comparison is now used by
- default when Unicode strings are compared with :meth:`~unittest.TestCase.assertEqual`.
-
-* :meth:`~unittest.TestCase.assertRegexpMatches` and
- :meth:`~unittest.TestCase.assertNotRegexpMatches` checks whether the
- first argument is a string matching or not matching the regular
- expression provided as the second argument (:issue:`8038`).
-
-* :meth:`~unittest.TestCase.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:`~unittest.TestCase.assertIn` and :meth:`~unittest.TestCase.assertNotIn`
- tests whether *first* is or is not in *second*.
-
-* :meth:`~unittest.TestCase.assertItemsEqual` tests whether two provided sequences
- contain the same elements.
-
-* :meth:`~unittest.TestCase.assertSetEqual` compares whether two sets are equal, and
- only reports the differences between the sets in case of error.
-
-* Similarly, :meth:`~unittest.TestCase.assertListEqual` and :meth:`~unittest.TestCase.assertTupleEqual`
- compare the specified types and explain any differences without necessarily
- printing their full values; these methods are now used by default
- when comparing lists and tuples using :meth:`~unittest.TestCase.assertEqual`.
- More generally, :meth:`~unittest.TestCase.assertSequenceEqual` compares two sequences
- and can optionally check whether both sequences are of a
- particular type.
-
-* :meth:`~unittest.TestCase.assertDictEqual` compares two dictionaries and reports the
- differences; it's now used by default when you compare two dictionaries
- using :meth:`~unittest.TestCase.assertEqual`. :meth:`~unittest.TestCase.assertDictContainsSubset` checks whether
- all of the key/value pairs in *first* are found in *second*.
-
-* :meth:`~unittest.TestCase.assertAlmostEqual` and :meth:`~unittest.TestCase.assertNotAlmostEqual` test
- whether *first* and *second* are approximately equal. This method
- can either round their difference to an optionally-specified number
- of *places* (the default is 7) and compare it to zero, or require
- the difference to be smaller than a supplied *delta* value.
-
-* :meth:`~unittest.TestLoader.loadTestsFromName` properly honors the
- :attr:`~unittest.TestLoader.suiteClass` attribute of
- the :class:`~unittest.TestLoader`. (Fixed by Mark Roddy; :issue:`6866`.)
-
-* A new hook lets you extend the :meth:`~unittest.TestCase.assertEqual` method to handle
- new data types. The :meth:`~unittest.TestCase.addTypeEqualityFunc` method takes a type
- object and a function. The function will be used 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 aren't matching, much as the new
- sequence comparison methods do.
-
-:func:`unittest.main` now takes an optional ``exit`` argument. If
-False, :func:`~unittest.main` doesn't call :func:`sys.exit`, allowing
-:func:`main` to be used from the interactive interpreter.
-(Contributed by J. Pablo Fernández; :issue:`3379`.)
-
-:class:`~unittest.TestResult` has new :meth:`~unittest.TestResult.startTestRun` and
-:meth:`~unittest.TestResult.stopTestRun` methods that are called immediately before
-and after a test run. (Contributed by Robert Collins; :issue:`5728`.)
-
-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 or used.
-
-.. seealso::
-
- http://www.voidspace.org.uk/python/articles/unittest2.shtml
- Describes the new features, how to use them, and the
- rationale for various design decisions. (By Michael Foord.)
-
-.. _elementtree-section:
-
-Updated module: ElementTree 1.3
----------------------------------
-
-The version of the ElementTree library included with Python was updated to
-version 1.3. Some of the new features are:
-
-* The various parsing functions now take a *parser* keyword argument
- giving an :class:`XMLParser` instance that will
- be used. This makes it possible to override the file's internal encoding::
-
- p = ET.XMLParser(encoding='utf-8')
- t = ET.XML("""<root/>""", parser=p)
-
- Errors in parsing XML now raise a :exc:`ParseError` exception, whose
- instances have a :attr:`position` attribute
- containing a (*line*, *column*) tuple giving the location of the problem.
-
-* ElementTree's code for converting trees to a string has been
- significantly reworked, making it roughly twice as fast in many
- cases. The :class:`ElementTree` :meth:`write` and :class:`Element`
- :meth:`write` methods now have a *method* parameter that can be
- "xml" (the default), "html", or "text". HTML mode will output empty
- elements as ``<empty></empty>`` instead of ``<empty/>``, and text
- mode will skip over elements and only output the text chunks. If
- you set the :attr:`tag` attribute of an element to ``None`` but
- leave its children in place, the element will be omitted when the
- tree is written out, so you don't need to do more extensive rearrangement
- to remove a single element.
-
- Namespace handling has also been improved. All ``xmlns:<whatever>``
- declarations are now output on the root element, not scattered throughout
- the resulting XML. You can set the default namespace for a tree
- by setting the :attr:`default_namespace` attribute and can
- register new prefixes with :meth:`register_namespace`. In XML mode,
- you can use the true/false *xml_declaration* parameter to suppress the
- XML declaration.
-
-* New :class:`Element` method: :meth:`extend` appends the items from a
- sequence to the element's children. Elements themselves behave like
- sequences, so it's easy to move children from one element to
- another::
-
- from xml.etree import ElementTree as ET
-
- t = ET.XML("""<list>
- <item>1</item> <item>2</item> <item>3</item>
- </list>""")
- new = ET.XML('<root/>')
- new.extend(t)
-
- # Outputs <root><item>1</item>...</root>
- print ET.tostring(new)
-
-* New :class:`Element` method: :meth:`iter` yields the children of the
- element as a generator. It's also possible to write ``for child in
- elem:`` to loop over an element's children. The existing method
- :meth:`getiterator` is now deprecated, as is :meth:`getchildren`
- which constructs and returns a list of children.
-
-* New :class:`Element` method: :meth:`itertext` yields all chunks of
- text that are descendants of the element. For example::
-
- t = ET.XML("""<list>
- <item>1</item> <item>2</item> <item>3</item>
- </list>""")
-
- # Outputs ['\n ', '1', ' ', '2', ' ', '3', '\n']
- print list(t.itertext())
-
-* Deprecated: using an element as a Boolean (i.e., ``if elem:``) would
- return true if the element had any children, or false if there were
- no children. This behaviour is confusing -- ``None`` is false, but
- so is a childless element? -- so it will now trigger a
- :exc:`FutureWarning`. In your code, you should be explicit: write
- ``len(elem) != 0`` if you're interested in the number of children,
- or ``elem is not None``.
-
-Fredrik Lundh develops ElementTree and produced the 1.3 version;
-you can read his article describing 1.3 at
-http://effbot.org/zone/elementtree-13-intro.htm.
-Florent Xicluna updated the version included with
-Python, after discussions on python-dev and in :issue:`6472`.)
-
-.. ======================================================================
-
-
-Build and C API Changes
-=======================
-
-Changes to Python's build process and to the C API include:
-
-* The latest release of the GNU Debugger, GDB 7, can be `scripted
- using Python
- <http://sourceware.org/gdb/current/onlinedocs/gdb/Python.html>`__.
- When you begin debugging an executable program P, GDB will look for
- a file named ``P-gdb.py`` and automatically read it. Dave Malcolm
- contributed a :file:`python-gdb.py` that adds a number of
- commands useful when debugging Python itself. For example,
- ``py-up`` and ``py-down`` go up or down one Python stack frame,
- which usually corresponds to several C stack frames. ``py-print``
- prints the value of a Python variable, and ``py-bt`` prints the
- Python stack trace. (Added as a result of :issue:`8032`.)
-
-* If you use the :file:`.gdbinit` file provided with Python,
- 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
- worker thread submit notifications to the main Python thread. This
- is particularly useful for asynchronous IO operations.
- (Contributed by Kristján Valur Jónsson; :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 for 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:`PyErr_NewExceptionWithDoc` creates a new
- exception class, just as the existing :cfunc:`PyErr_NewException` does,
- but takes an extra ``char *`` argument containing the docstring for the
- new exception class. (Added by 'lekma' on the Python bug tracker;
- :issue:`7033`.)
-
-* 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 functions: :cfunc:`PyLong_AsLongAndOverflow` and
- :cfunc:`PyLong_AsLongLongAndOverflow` approximates a Python long
- integer as a C :ctype:`long` or :ctype:`long long`.
- If the number is too large to fit into
- the output type, an *overflow* flag is set and returned to the caller.
- (Contributed by Case Van Horsen; :issue:`7528` and :issue:`7767`.)
-
-* New function: stemming from the rewrite of string-to-float conversion,
- a new :cfunc:`PyOS_string_to_double` function was added. The old
- :cfunc:`PyOS_ascii_strtod` and :cfunc:`PyOS_ascii_atof` functions
- are now deprecated.
-
-* New function: :cfunc:`PySys_SetArgvEx` sets the value of
- ``sys.argv`` and can optionally update ``sys.path`` to include the
- directory containing the script named by ``sys.argv[0]`` depending
- on the value of an *updatepath* parameter.
-
- This function was added to close a security hole for applications
- that embed Python. The old function, :cfunc:`PySys_SetArgv`, would
- always update ``sys.path``, and sometimes it would add the current
- directory. This meant that, if you ran an application embedding
- Python in a directory controlled by someone else, attackers could
- put a Trojan-horse module in the directory (say, a file named
- :file:`os.py`) that your application would then import and run.
-
- If you maintain a C/C++ application that embeds Python, check
- whether you're calling :cfunc:`PySys_SetArgv` and carefully consider
- whether the application should be using :cfunc:`PySys_SetArgvEx`
- with *updatepath* set to false.
-
- Security issue reported as `CVE-2008-5983
- <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5983>`_;
- discussed in :issue:`5753`, and fixed by Antoine Pitrou.
-
-* 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.
-
-* Removed function: :cmacro:`PyEval_CallObject` is now only available
- as a macro. A function version was being kept around to preserve
- ABI linking compatibility, but that was in 1997; it can certainly be
- deleted by now. (Removed by Antoine Pitrou; :issue:`8276`.)
-
-* New format codes: the :cfunc:`PyFormat_FromString`,
- :cfunc:`PyFormat_FromStringV`, and :cfunc:`PyErr_Format` functions now
- accept ``%lld`` and ``%llu`` format codes for displaying
- C's :ctype:`long long` types.
- (Contributed by Mark Dickinson; :issue:`7228`.)
-
-* 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 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`.)
-
-* The :cfunc:`Py_Finalize` function now calls the internal
- :func:`threading._shutdown` function; this prevents some exceptions from
- being raised when an interpreter shuts down.
- (Patch by Adam Olsen; :issue:`1722344`.)
-
-* When using the :ctype:`PyMemberDef` structure to define attributes
- of a type, Python will no longer let you try to delete or set a
- :const:`T_STRING_INPLACE` attribute.
-
- .. rev 79644
-
-* Global symbols defined by the :mod:`ctypes` module are now prefixed
- with ``Py``, or with ``_ctypes``. (Implemented by Thomas
- Heller; :issue:`3102`.)
-
-* New configure option: the :option:`--with-system-expat` switch allows
- building the :mod:`pyexpat` module to use the system Expat library.
- (Contributed by Arfrever Frehtes Taifersar Arahesis; :issue:`7609`.)
-
-* New configure option: the
- :option:`--with-valgrind` option will now disable the pymalloc
- allocator, which is difficult for the Valgrind memory-error detector
- to analyze correctly.
- Valgrind will therefore be better at detecting memory leaks and
- overruns. (Contributed by James Henstridge; :issue:`2422`.)
-
-* New configure option: you can now supply an empty string to
- :option:`--with-dbmliborder=` in order to disable all of the various
- DBM modules. (Added by Arfrever Frehtes Taifersar Arahesis;
- :issue:`6491`.)
-
-* 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`.)
-
- :program:`configure` also now sets a :envvar:`LDCXXSHARED` Makefile
- variable for supporting C++ linking. (Contributed by Arfrever
- Frehtes Taifersar Arahesis; :issue:`1222585`.)
-
-* 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`.)
-
-
-.. _whatsnew27-capsules:
-
-Capsules
--------------------
-
-Python 3.1 adds a new C datatype, :ctype:`PyCapsule`, for providing a
-C API to an extension module. A capsule is essentially the holder of
-a C ``void *`` pointer, and is made available as a module attribute; for
-example, the :mod:`socket` module's API is exposed as ``socket.CAPI``,
-and :mod:`unicodedata` exposes ``ucnhash_CAPI``. Other extensions
-can import the module, access its dictionary to get the capsule
-object, and then get the ``void *`` pointer, which will usually point
-to an array of pointers to the module's various API functions.
-
-There is an existing data type already used for this,
-:ctype:`PyCObject`, but it doesn't provide type safety. Evil code
-written in pure Python could cause a segmentation fault by taking a
-:ctype:`PyCObject` from module A and somehow substituting it for the
-:ctype:`PyCObject` in module B. Capsules know their own name,
-and getting the pointer requires providing the name::
-
- void *vtable;
-
- if (!PyCapsule_IsValid(capsule, "mymodule.CAPI") {
- PyErr_SetString(PyExc_ValueError, "argument type invalid");
- return NULL;
- }
-
- vtable = PyCapsule_GetPointer(capsule, "mymodule.CAPI");
-
-You are assured that ``vtable`` points to whatever you're expecting.
-If a different capsule was passed in, :cfunc:`PyCapsule_IsValid` would
-detect the mismatched name and return false. Refer to
-:ref:`using-capsules` for more information on using these objects.
-
-Python 2.7 now uses capsules internally to provide various
-extension-module APIs, but the :cfunc:`PyCObject_AsVoidPtr` was
-modified to handle capsules, preserving compile-time compatibility
-with the :ctype:`CObject` interface. Use of
-:cfunc:`PyCObject_AsVoidPtr` will signal a
-:exc:`PendingDeprecationWarning`, which is silent by default.
-
-Implemented in Python 3.1 and backported to 2.7 by Larry Hastings;
-discussed in :issue:`5630`.
-
-
-.. ======================================================================
-
-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 :mod:`_winreg` module for accessing the registry now implements
- the :func:`CreateKeyEx` and :func:`DeleteKeyEx` functions, extended
- versions of previously-supported functions that take several extra
- arguments. The :func:`DisableReflectionKey`,
- :func:`EnableReflectionKey`, and :func:`QueryReflectionKey` were also
- tested and documented.
- (Implemented by Brian Curtin: :issue:`7347`.)
-
-* The new :cfunc:`_beginthreadex` API is used to start threads, and
- the native thread-local storage functions are now used.
- (Contributed by Kristján Valur Jónsson; :issue:`3582`.)
-
-* The :func:`os.kill` function now works on Windows. The signal value
- can be the constants :const:`CTRL_C_EVENT`,
- :const:`CTRL_BREAK_EVENT`, or any integer. The first two constants
- will send Control-C and Control-Break keystroke events to
- subprocesses; any other value will use the :cfunc:`TerminateProcess`
- API. (Contributed by Miki Tebeka; :issue:`1220212`.)
-
-* The :func:`os.listdir` function now correctly fails
- for an empty path. (Fixed by Hirokazu Yamamoto; :issue:`5913`.)
-
-* The :mod:`mimelib` module will now read the MIME database from
- the Windows registry when initializing.
- (Patch by Gabriel Genellina; :issue:`4969`.)
-
-.. ======================================================================
-
-Port-Specific Changes: Mac OS X
------------------------------------
-
-* 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`.)
-
-Port-Specific Changes: FreeBSD
------------------------------------
-
-* FreeBSD 7.1's :const:`SO_SETFIB` constant, used with
- :func:`~socket.getsockopt`/:func:`~socket.setsockopt` to select an
- alternate routing table, is now available in the :mod:`socket`
- module. (Added by Kyle VanderBeek; :issue:`8235`.)
-
-Other Changes and Fixes
-=======================
-
-* Two benchmark scripts, :file:`iobench` and :file:`ccbench`, were
- added to the :file:`Tools` directory. :file:`iobench` measures the
- speed of the built-in file I/O objects returned by :func:`open`
- while performing various operations, and :file:`ccbench` is a
- concurrency benchmark that tries to measure computing throughput,
- thread switching latency, and IO processing bandwidth when
- performing several tasks using a varying number of threads.
-
-* The :file:`Tools/i18n/msgfmt.py` script now understands plural
- forms in :file:`.po` files. (Fixed by Martin von Löwis;
- :issue:`5464`.)
-
-* 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 reports the seed that was used
- (Added by Collin Winter.)
-
-* Another :file:`regrtest.py` switch is :option:`-j`, which
- takes an integer specifying how many tests run in parallel. This
- 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 can also be used
- with a new :option:`-F` switch that runs selected tests in a loop
- until they fail. (Added by Antoine Pitrou; :issue:`7312`.)
-
-* When executed as a script, the :file:`py_compile.py` module now
- accepts ``'-'`` as an argument, which will read standard input for
- the list of filenames to be compiled. (Contributed by Piotr
- Ożarowski; :issue:`8233`.)
-
-.. ======================================================================
-
-Porting to Python 2.7
-=====================
-
-This section lists previously described changes and other bugfixes
-that may require changes to your code:
-
-* The :func:`range` function processes its arguments more
- consistently; it will now call :meth:`__int__` on non-float,
- non-integer arguments that are supplied to it. (Fixed by Alexander
- Belopolsky; :issue:`1533`.)
-
-* The string :meth:`format` method changed the default precision used
- for floating-point and complex numbers 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
- affects new-style classes (derived from :class:`object`) and C extension
- types. (:issue:`6101`.)
-
-* Due to a bug in Python 2.6, the *exc_value* parameter to
- :meth:`__exit__` methods was often the string representation of the
- exception, not an instance. This was fixed in 2.7, so *exc_value*
- will be an instance as expected. (Fixed by Florent Xicluna;
- :issue:`7853`.)
-
-* When a restricted set of attributes were set using ``__slots__``,
- deleting an unset attribute would not raise :exc:`AttributeError`
- as you would expect. Fixed by Benjamin Peterson; :issue:`7604`.)
-
-In the standard library:
-
-* Operations with :class:`datetime` instances that resulted in a year
- falling outside the supported range didn't always raise
- :exc:`OverflowError`. Such errors are now checked more carefully
- and will now raise the exception. (Reported by Mark Leander, patch
- by Anand B. Pillai and Alexander Belopolsky; :issue:`7150`.)
-
-* 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`.)
-
- Comparisons involving a signaling NaN value (or ``sNAN``) now signal
- :const:`InvalidOperation` instead of silently returning a true or
- false value depending on the comparison operator. Quiet NaN values
- (or ``NaN``) are now hashable. (Fixed by Mark Dickinson;
- :issue:`7279`.)
-
-* The ElementTree library, :mod:`xml.etree`, no longer escapes
- ampersands and angle brackets when outputting an XML processing
- instruction (which looks like `<?xml-stylesheet href="#style1"?>`)
- or comment (which looks like `<!-- comment -->`).
- (Patch by Neil Muller; :issue:`2746`.)
-
-* The :meth:`readline` method of :class:`StringIO` objects now does
- nothing when a negative length is requested, as other file-like
- objects do. (:issue:`7348`).
-
-* The :mod:`syslog` module will now use the value of ``sys.argv[0]`` as the
- identifier instead of the previous default value of ``'python'``.
- (Changed by Sean Reifschneider; :issue:`8451`.)
-
-* The :mod:`tarfile` module's default error handling has changed, to
- no longer suppress fatal errors. The default error level was previously 0,
- which meant that errors would only result in a message being written to the
- debug log, but because the debug log is not activated by default,
- these errors go unnoticed. The default error level is now 1,
- which raises an exception if there's an error.
- (Changed by Lars Gustäbel; :issue:`7357`.)
-
-* The :mod:`urlparse` module's :func:`~urlparse.urlsplit` now handles
- unknown URL schemes in a fashion compliant with :rfc:`3986`: if the
- URL is of the form ``"<something>://..."``, the text before the
- ``://`` is treated as the scheme, even if it's a made-up scheme that
- the module doesn't know about. This change may break code that
- worked around the old behaviour. For example, Python 2.6.4 or 2.5
- will return the following:
-
- >>> import urlparse
- >>> urlparse.urlsplit('invented://host/filename?query')
- ('invented', '', '//host/filename?query', '', '')
-
- Python 2.7 (and Python 2.6.5) will return:
-
- >>> import urlparse
- >>> urlparse.urlsplit('invented://host/filename?query')
- ('invented', 'host', '/filename?query', '', '')
-
- (Python 2.7 actually produces slightly different output, since it
- returns a named tuple instead of a standard tuple.)
-
-For C extensions:
-
-* C extensions that use integer format codes with the ``PyArg_Parse*``
- family of functions will now raise a :exc:`TypeError` exception
- instead of triggering a :exc:`DeprecationWarning` (:issue:`5080`).
-
-* Use the new :cfunc:`PyOS_string_to_double` function instead of the old
- :cfunc:`PyOS_ascii_strtod` and :cfunc:`PyOS_ascii_atof` functions,
- which are now deprecated.
-
-For applications that embed Python:
-
-* The :cfunc:`PySys_SetArgvEx` function was added, letting
- applications close a security hole when the existing
- :cfunc:`PySys_SetArgv` function was used. Check whether you're
- calling :cfunc:`PySys_SetArgv` and carefully consider whether the
- application should be using :cfunc:`PySys_SetArgvEx` with
- *updatepath* set to false.
-
-.. ======================================================================
-
-
-.. _acks27:
-
-Acknowledgements
-================
-
-The author would like to thank the following people for offering
-suggestions, corrections and assistance with various drafts of this
-article: Nick Coghlan, Philip Jenvey, Ryan Lovett, R. David Murray,
-Hugh Secker-Walker.
-
Modified: python/branches/release31-maint/Doc/whatsnew/index.rst
==============================================================================
--- python/branches/release31-maint/Doc/whatsnew/index.rst (original)
+++ python/branches/release31-maint/Doc/whatsnew/index.rst Sun Jul 11 12:41:44 2010
@@ -13,7 +13,6 @@
3.1.rst
3.0.rst
- 2.7.rst
2.6.rst
2.5.rst
2.4.rst
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