**************************** What's New In Python 3.3 **************************** :Author: Raymond Hettinger :Release: |release| :Date: |today| .. $Id$ 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 as a comment: % Patch 12345 XXX Describe the transmogrify() function added to the socket module. (Contributed by P.Y. Developer.) This saves the maintainer the effort of going through the SVN log when researching a change. This article explains the new features in Python 3.3, compared to 3.2. PEP XXX: Stub ============= Other Language Changes ====================== Some smaller changes made to the core Python language are: * Stub New, Improved, and Deprecated Modules ===================================== * Stub codecs ------ Multibyte CJK decoders now resynchronize faster. They only ignore the first byte of an invalid byte sequence. For example, ``b'\xff\n'.decode('gb2312', 'replace')`` now returns a ``\n`` after the replacement character. (:issue:`12016`) Don't reset incremental encoders of CJK codecs at each call to their encode() method anymore. For example:: $ ./python -q >>> import codecs >>> encoder = codecs.getincrementalencoder('hz')('strict') >>> b''.join(encoder.encode(x) for x in '\u52ff\u65bd\u65bc\u4eba\u3002 Bye.') b'~{NpJ)l6HK!#~} Bye.' This example gives ``b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~} Bye.'`` with older Python versions. (:issue:`12100`) curses ------ The :class:`curses.window` class has a new :class:`~curses.window.get_wch` method to a wide character. Patch by Iñigo Serna. (:issue:`6755`) faulthandler ------------ New module: :mod:`faulthandler`. * :envvar:`PYTHONFAULTHANDLER` * :option:`-X` ``faulthandler`` math ---- The :mod:`math` module has a new function: * :func:`~math.log2`: return the base-2 logarithm of *x* (Written by Mark Dickinson in :issue:`11888`). nntplib ------- The :class:`nntplib.NNTP` class now supports the context manager protocol to unconditionally consume :exc:`socket.error` exceptions and to close the NNTP connection when done:: >>> from nntplib import NNTP >>> with NNTP('news.gmane.org') as n: ... n.group('gmane.comp.python.committers') ... ('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.python.committers') >>> (Contributed by Giampaolo Rodolà in :issue:`9795`) os -- * The :mod:`os` module has a new :func:`~os.pipe2` function that makes it possible to create a pipe with :data:`~os.O_CLOEXEC` or :data:`~os.O_NONBLOCK` flags set atomically. This is especially useful to avoid race conditions in multi-threaded programs. * The :mod:`os` module has a new :func:`~os.sendfile` function which provides an efficent "zero-copy" way for copying data from one file (or socket) descriptor to another. The phrase "zero-copy" refers to the fact that all of the copying of data between the two descriptors is done entirely by the kernel, with no copying of data into userspace buffers. :func:`~os.sendfile` can be used to efficiently copy data from a file on disk to a network socket, e.g. for downloading a file. (Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.) * The :mod:`os` module has two new functions: :func:`~os.getpriority` and :func:`~os.setpriority`. They can be used to get or set process niceness/priority in a fashion similar to :func:`os.nice` but extended to all processes instead of just the current one. (Patch submitted by Giampaolo Rodolà in :issue:`10784`.) packaging --------- :mod:`distutils` has undergone additions and refactoring under a new name, :mod:`packaging`, to allow developers to break backward compatibility. :mod:`distutils` is still provided in the standard library, but users are encouraged to transition to :mod:`packaging`. For older versions of Python, a backport compatible with 2.4+ and 3.1+ will be made available on PyPI under the name :mod:`distutils2`. .. TODO add examples and howto to the packaging docs and link to them pydoc ----- The Tk GUI and the :func:`~pydoc.serve` function have been removed from the :mod:`pydoc` module: ``pydoc -g`` and :func:`~pydoc.serve` have been deprecated in Python 3.2. sys --- * The :mod:`sys` module has a new :func:`~sys.thread_info` :term:`struct sequence` holding informations about the thread implementation. (:issue:`11223`) signal ------ * The :mod:`signal` module has new functions: * :func:`~signal.pthread_sigmask`: fetch and/or change the signal mask of the calling thread (Contributed by Jean-Paul Calderone in :issue:`8407`) ; * :func:`~signal.pthread_kill`: send a signal to a thread ; * :func:`~signal.sigpending`: examine pending functions ; * :func:`~signal.sigwait`: wait a signal. * :func:`~signal.sigwaitinfo`: wait for a signal, returning detailed information about it. * :func:`~signal.sigtimedwait`: like :func:`~signal.sigwaitinfo` but with a timeout. * The signal handler writes the signal number as a single byte instead of a nul byte into the wakeup file descriptor. So it is possible to wait more than one signal and know which signals were raised. * :func:`signal.signal` and :func:`signal.siginterrupt` raise an OSError, instead of a RuntimeError: OSError has an errno attribute. ssl --- The :mod:`ssl` module has new functions: * :func:`~ssl.RAND_bytes`: generate cryptographically strong pseudo-random bytes. * :func:`~ssl.RAND_pseudo_bytes`: generate pseudo-random bytes. ftplib ------ The :class:`~ftplib.FTP_TLS` class now provides a new :func:`~ftplib.FTP_TLS.ccc` function to revert control channel back to plaintex. This can be useful to take advantage of firewalls that know how to handle NAT with non-secure FTP without opening fixed ports. (Contributed by Giampaolo Rodolà in :issue:`12139`) shutil ------ The :mod:`shutil` module has a new :func:`~shutil.disk_usage` function providing total, used and free disk space statistics. (Contributed by Giampaolo Rodolà in :issue:`12442`) Optimizations ============= Major performance enhancements have been added: * Stub Build and C API Changes ======================= Changes to Python's build process and to the C API include: * Stub Unsupported Operating Systems ============================= OS/2 and VMS are no longer supported due to the lack of a maintainer. Windows 2000 and Windows platforms which set ``COMSPEC`` to ``command.com`` are no longer supported due to maintenance burden. Porting to Python 3.3 ===================== This section lists previously described changes and other bugfixes that may require changes to your code: * Stub .. Issue #11591: When :program:`python` was started with :option:`-S`, ``import site`` will not add site-specific paths to the module search paths. In previous versions, it did. See changeset for doc changes in various files. Contributed by Carl Meyer with editions by Éric Araujo. .. Issue #10998: -Q command-line flags are related artifacts have been removed. Code checking sys.flags.division_warning will need updating. Contributed by Éric Araujo.