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ReStructuredText
415 lines
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ReStructuredText
****************************
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What's New In Python 3.5
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****************************
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:Release: |release|
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:Date: |today|
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.. Rules for maintenance:
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* Anyone can add text to this document. Do not spend very much time
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on the wording of your changes, because your text will probably
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get rewritten to some degree.
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* The maintainer will go through Misc/NEWS periodically and add
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changes; it's therefore more important to add your changes to
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Misc/NEWS than to this file.
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* This is not a complete list of every single change; completeness
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is the purpose of Misc/NEWS. Some changes I consider too small
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or esoteric to include. If such a change is added to the text,
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I'll just remove it. (This is another reason you shouldn't spend
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too much time on writing your addition.)
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* If you want to draw your new text to the attention of the
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maintainer, add 'XXX' to the beginning of the paragraph or
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section.
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* It's OK to just add a fragmentary note about a change. For
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example: "XXX Describe the transmogrify() function added to the
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socket module." The maintainer will research the change and
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write the necessary text.
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* You can comment out your additions if you like, but it's not
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necessary (especially when a final release is some months away).
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* Credit the author of a patch or bugfix. Just the name is
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sufficient; the e-mail address isn't necessary.
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* It's helpful to add the bug/patch number as a comment:
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XXX Describe the transmogrify() function added to the socket
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module.
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(Contributed by P.Y. Developer in :issue:`12345`.)
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This saves the maintainer the effort of going through the Mercurial log
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when researching a change.
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This article explains the new features in Python 3.5, compared to 3.4.
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For full details, see the :source:`Misc/NEWS` file.
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.. note:: Prerelease users should be aware that this document is currently in
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draft form. It will be updated substantially as Python 3.5 moves towards
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release, so it's worth checking back even after reading earlier versions.
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.. seealso::
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:pep:`478` - Python 3.5 Release Schedule
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Summary -- Release highlights
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=============================
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.. This section singles out the most important changes in Python 3.3.
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Brevity is key.
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New syntax features:
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* None yet.
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New library modules:
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* None yet.
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New built-in features:
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* None yet.
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Implementation improvements:
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* When the ``LC_TYPE`` locale is the POSIX locale (``C`` locale),
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:py:data:`sys.stdin` and :py:data:`sys.stdout` are now using the
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``surrogateescape`` error handler, instead of the ``strict`` error handler
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(:issue:`19977`).
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Significantly Improved Library Modules:
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* None yet.
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Security improvements:
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* None yet.
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Please read on for a comprehensive list of user-facing changes.
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.. PEP-sized items next.
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.. _pep-4XX:
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.. PEP 4XX: Virtual Environments
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.. =============================
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.. (Implemented by Foo Bar.)
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.. .. seealso::
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:pep:`4XX` - Python Virtual Environments
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PEP written by Carl Meyer
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Other Language Changes
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======================
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Some smaller changes made to the core Python language are:
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* None yet.
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New Modules
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===========
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.. module name
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.. -----------
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* None yet.
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Improved Modules
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================
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code
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----
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* The :func:`code.InteractiveInterpreter.showtraceback` method now prints
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the full chained traceback, just like the interactive interpreter
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(contributed by Claudiu.Popa in :issue:`17442`).
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compileall
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----------
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* :func:`compileall.compile_dir` and :mod:`compileall`'s command-line interface
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can now do parallel bytecode compilation.
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(Contributed by Claudiu Popa in :issue:`16104`).
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doctest
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-------
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* :func:`doctest.DocTestSuite` returns an empty :class:`unittest.TestSuite` if
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*module* contains no docstrings instead of raising :exc:`ValueError`
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(contributed by Glenn Jones in :issue:`15916`).
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glob
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----
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* :func:`~glob.iglob` and :func:`~glob.glob` now support recursive search in
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subdirectories using the "``**``" pattern.
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(Contributed by Serhiy Storchaka in :issue:`13968`.)
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imaplib
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-------
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* :class:`IMAP4` now supports the context management protocol. When used in a
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:keyword:`with` statement, the IMAP4 ``LOGOUT`` command will be called
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automatically at the end of the block. (Contributed by Tarek Ziadé and
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Serhiy Storchaka in :issue:`4972`).
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imghdr
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------
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* :func:`~imghdr.what` now recognizes the `OpenEXR <http://www.openexr.com>`_
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format (contributed by Martin vignali and Cladui Popa in :issue:`20295`).
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importlib
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---------
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* :class:`importlib.util.LazyLoader` allows for the lazy loading of modules in
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applications where startup time is paramount (contributed by Brett Cannon in
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:issue:`17621`).
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* :func:`importlib.abc.InspectLoader.source_to_code` is now a
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static method to make it easier to work with source code in a string.
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With a module object that you want to initialize you can then use
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``exec(code, module.__dict__)`` to execute the code in the module.
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* :func:`importlib.util.module_from_spec` is now the preferred way to create a
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new module. Compared to :class:`types.ModuleType`, this new function will set
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the various import-controlled attributes based on the passed-in spec object.
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inspect
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-------
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* :class:`inspect.Signature` and :class:`inspect.Parameter` are now
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picklable and hashable (contributed by Yury Selivanov in :issue:`20726`
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and :issue:`20334`).
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* New class method :meth:`inspect.Signature.from_callable`, which makes
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subclassing of :class:`~inspect.Signature` easier (contributed
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by Yury Selivanov and Eric Snow in :issue:`17373`).
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ipaddress
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---------
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* :class:`ipaddress.IPv4Network` and :class:`ipaddress.IPv6Network` now
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accept an ``(address, netmask)`` tuple argument, so as to easily construct
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network objects from existing addresses (contributed by Peter Moody
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and Antoine Pitrou in :issue:`16531`).
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os
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--
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* :class:`os.stat_result` now has a :attr:`~os.stat_result.st_file_attributes`
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attribute on Windows (contributed by Ben Hoyt in :issue:`21719`).
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re
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--
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* Number of capturing groups in regular expression is no longer limited by 100.
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(Contributed by Serhiy Storchaka in :issue:`22437`.)
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shutil
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------
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* :func:`~shutil.move` now accepts a *copy_function* argument, allowing,
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for example, :func:`~shutil.copy` to be used instead of the default
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:func:`~shutil.copy2` if there is a need to ignore metadata. (Contributed by
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Claudiu Popa in :issue:`19840`.)
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signal
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------
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* Different constants of :mod:`signal` module are now enumeration values using
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the :mod:`enum` module. This allows meaningful names to be printed during
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debugging, instead of integer “magic numbers”. (contributed by Giampaolo
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Rodola' in :issue:`21076`)
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smtpd
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-----
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* Both :class:`~smtpd.SMTPServer` and :class:`smtpd.SMTPChannel` now accept a
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*decode_data* keyword to determine if the DATA portion of the SMTP
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transaction is decoded using the ``utf-8`` codec or is instead provided to
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:meth:`~smtpd.SMTPServer.process_message` as a byte string. The default
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is ``True`` for backward compatibility reasons, but will change to ``False``
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in Python 3.6. (Contributed by Maciej Szulik in :issue:`19662`.)
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* It is now possible to provide, directly or via name resolution, IPv6
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addresses in the :class:`~smtpd.SMTPServer` constructor, and have it
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successfully connect. (Contributed by Milan Oberkirch in :issue:`14758`.)
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* :mod:`~smtpd.SMTPServer` now supports :rfc:`6531` via the *enable_SMTPUTF8*
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constructor argument and a user-provided
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:meth:`~smtpd.SMTPServer.process_smtputf8_message` method.
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smtplib
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-------
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* A new :meth:`~smtplib.SMTP.auth` method provides a convenient way to
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implement custom authentication mechanisms (contributed by Milan Oberkirch in
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:issue:`15014`).
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sndhdr
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------
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* :func:`~sndhdr.what` and :func:`~sndhdr.whathdr` now return
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:func:`~collections.namedtuple` \s (contributed by Claudiu Popa in
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:issue:`18615`).
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socket
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------
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* New :meth:`socket.socket.sendfile` method allows to send a file over a socket
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by using high-performance :func:`os.sendfile` function on UNIX resulting in
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uploads being from 2x to 3x faster than when using plain
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:meth:`socket.socket.send`.
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(contributed by Giampaolo Rodola' in :issue:`17552`)
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time
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----
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* The :func:`time.monotonic` function is now always available. (Contributed by
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Victor Stinner in :issue:`22043`.)
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wsgiref
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-------
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* *headers* parameter of :class:`wsgiref.headers.Headers` is now optional.
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(Contributed by Pablo Torres Navarrete and SilentGhost in :issue:`5800`.)
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xmlrpc
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------
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* :class:`xmlrpc.client.ServerProxy` is now a :term:`context manager`
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(contributed by Claudiu Popa in :issue:`20627`).
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Optimizations
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=============
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The following performance enhancements have been added:
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* Construction of ``bytes(int)`` (filled by zero bytes) is faster and use less
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memory for large objects. ``calloc()`` is used instead of ``malloc()`` to
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allocate memory for these objects.
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* Some operations on :class:`~ipaddress.IPv4Network` and
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:class:`~ipaddress.IPv6Network` have been massively sped up, such as
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:meth:`~ipaddress.IPv4Network.subnets`, :meth:`~ipaddress.IPv4Network.supernet`,
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:func:`~ipaddress.summarize_address_range`, :func:`~ipaddress.collapse_addresses`.
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The speed up can range from 3x to 15x.
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(:issue:`21486`, :issue:`21487`, :issue:`20826`)
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Build and C API Changes
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=======================
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Changes to Python's build process and to the C API include:
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* New ``calloc`` functions:
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* :c:func:`PyMem_RawCalloc`
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* :c:func:`PyMem_Calloc`
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* :c:func:`PyObject_Calloc`
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* :c:func:`_PyObject_GC_Calloc`
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Deprecated
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==========
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Unsupported Operating Systems
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-----------------------------
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* None yet.
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Deprecated Python modules, functions and methods
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------------------------------------------------
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* The :mod:`formatter` module has now graduated to full deprecation and is still
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slated for removal in Python 3.6.
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* :mod:`smtpd` has in the past always decoded the DATA portion of email
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messages using the ``utf-8`` codec. This can now be controlled by the new
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*decode_data* keyword to :class:`~smtpd.SMTPServer`. The default value is
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``True``, but this default is deprecated. Specify the *decode_data* keyword
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with an appropriate value to avoid the deprecation warning.
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Deprecated functions and types of the C API
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-------------------------------------------
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* None yet.
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Deprecated features
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-------------------
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* None yet.
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Removed
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=======
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* The ``__version__`` attribute has been dropped from the email package. The
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email code hasn't been shipped separately from the stdlib for a long time,
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and the ``__version__`` string was not updated in the last few releases.
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Porting to Python 3.5
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=====================
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This section lists previously described changes and other bugfixes
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that may require changes to your code.
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Changes in the Python API
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-------------------------
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* Before Python 3.5, a :class:`datetime.time` object was considered to be false
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if it represented midnight in UTC. This behavior was considered obscure and
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error-prone and has been removed in Python 3.5. See :issue:`13936` for full
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details.
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* :meth:`ssl.SSLSocket.send()` now raises either :exc:`ssl.SSLWantReadError`
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or :exc:`ssl.SSLWantWriteError` on a non-blocking socket if the operation
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would block. Previously, it would return 0. See :issue:`20951`.
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* The ``__name__`` attribute of generator is now set from the function name,
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instead of being set from the code name. Use ``gen.gi_code.co_name`` to
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retrieve the code name. Generators also have a new ``__qualname__``
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attribute, the qualified name, which is now used for the representation
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of a generator (``repr(gen)``). See :issue:`21205`.
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* The deprecated "strict" mode and argument of :class:`~html.parser.HTMLParser`,
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:meth:`HTMLParser.error`, and the :exc:`HTMLParserError` exception have been
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removed (contributed by Ezio Melotti in :issue:`15114`).
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The *convert_charrefs* argument of :class:`~html.parser.HTMLParser` is
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now ``True`` by default (contributed by Berker Peksag in :issue:`21047`).
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* Although it is not formally part of the API, it is worth noting for porting
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purposes (ie: fixing tests) that error messages that were previously of the
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form "'sometype' does not support the buffer protocol" are now of the form "a
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bytes-like object is required, not 'sometype'" (contributed by Ezio Melotti
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in :issue:`16518`).
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Changes in the C API
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--------------------
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* The :c:type:`PyMemAllocator` structure was renamed to
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:c:type:`PyMemAllocatorEx` and a new ``calloc`` field was added.
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