792 lines
32 KiB
ReStructuredText
792 lines
32 KiB
ReStructuredText
****************************
|
|
What's New In Python 3.2
|
|
****************************
|
|
|
|
: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 issue number:
|
|
|
|
XXX Describe the transmogrify() function added to the socket
|
|
module.
|
|
|
|
(Contributed by P.Y. Developer; :issue:`12345`.)
|
|
|
|
This saves the maintainer the effort of going through the SVN log
|
|
when researching a change.
|
|
|
|
This article explains the new features in Python 3.2, compared to 3.1.
|
|
|
|
PEP 384: Defining a Stable ABI
|
|
==============================
|
|
|
|
In the past, extension modules built for one Python version were often
|
|
not usable with other Python versions. Particularly on Windows, every
|
|
feature release of Python required rebuilding all extension modules that
|
|
one wanted to use. This requirement was the result of the free access to
|
|
Python interpreter internals that extension modules could use.
|
|
|
|
With Python 3.2, an alternative approach becomes available: extension
|
|
modules with restrict themselves to a limited API (by defining
|
|
Py_LIMITED_API) cannot use many of the internals, but are constrained
|
|
to a set of API functions that are promised to be stable for several
|
|
releases. As a consequence, extension modules built for 3.2 in that
|
|
mode will also work with 3.3, 3.4, and so on. Extension modules that
|
|
make use of details of memory structures can still be built, but will
|
|
need to be recompiled for every feature release.
|
|
|
|
|
|
PEP 391: Dictionary Based Configuration for Logging
|
|
====================================================
|
|
|
|
The :mod:`logging` module provided two kinds of configuration, one style with
|
|
function calls for each option or another style driven by an external file saved
|
|
in a :mod:`ConfigParser` format. Those options did not provide the flexibility
|
|
to create configurations from JSON or YAML files, nor did they support
|
|
incremental configuration, which is needed for specifying logger options from a
|
|
command line.
|
|
|
|
To support a more flexible style, the module now offers
|
|
:func:`logging.config.dictConfig` for specifying logging configuration with
|
|
plain Python dictionaries. The configuration options include formatters,
|
|
handlers, filters, and loggers. Here's a working example of a configuration
|
|
dictionary::
|
|
|
|
{"version": 1,
|
|
"formatters": {"brief": {"format": "%(levelname)-8s: %(name)-15s: %(message)s"},
|
|
"full": {"format": "%(asctime)s %(name)-15s %(levelname)-8s %(message)s"},
|
|
},
|
|
"handlers": {"console": {
|
|
"class": "logging.StreamHandler",
|
|
"formatter": "brief",
|
|
"level": "INFO",
|
|
"stream": "ext://sys.stdout"},
|
|
"console_priority": {
|
|
"class": "logging.StreamHandler",
|
|
"formatter": "full",
|
|
"level": "ERROR",
|
|
"stream": "ext://sys.stderr"},
|
|
},
|
|
"root": {"level": "DEBUG", "handlers": ["console", "console_priority"]}}
|
|
|
|
|
|
If that dictionary is stored in a file called "conf.json", it can loaded
|
|
and called with code like this::
|
|
|
|
>>> import logging.config
|
|
>>> logging.config.dictConfig(json.load(open('conf.json', 'rb')))
|
|
>>> logging.info("Transaction completed normally")
|
|
>>> logging.critical("Abnormal termination")
|
|
|
|
.. seealso::
|
|
|
|
:pep:`391` - Dictionary Based Configuration for Logging
|
|
PEP written by Vinay Sajip.
|
|
|
|
PEP 3148: The ``concurrent.futures`` module
|
|
============================================
|
|
|
|
.. (Stub section)
|
|
|
|
|
|
PEP 3147: PYC Repository Directories
|
|
=====================================
|
|
|
|
Python's scheme for caching bytecode in *.pyc* files did not work well in
|
|
environments with multiple python interpreters. If one interpreter encountered
|
|
a cached file created by another interpreter, it would recompile the source and
|
|
overwrite the cached file, thus losing the benefits of caching.
|
|
|
|
The issue of "pyc fights" has become more pronounced as it has become
|
|
commonplace for Linux distributions to ship with multiple versions of Python.
|
|
These conflicts also arise with CPython alternatives such as Unladen Swallow.
|
|
|
|
To solve this problem, Python's import machinery has been extended to use
|
|
distinct filenames for each interpreter. Instead of Python 3.2 and Python 3.3 and
|
|
Unladen Swallow each competing for a file called "mymodule.pyc", they will now
|
|
look for "mymodule.cpython-32.pyc", "mymodule.cpython-33.pyc", and
|
|
"mymodule.unladen10.pyc". And to prevent all of these new files from
|
|
cluttering source directories, the *pyc* files are now collected in a
|
|
"__pycache__" directory stored under the package directory.
|
|
|
|
Aside from the filenames and target directories, the new scheme has a few
|
|
aspects that are visible to the programmer:
|
|
|
|
* Imported modules now have a :attr:`__cached__` attribute which stores the name
|
|
of the actual file that was imported:
|
|
|
|
>>> import collections
|
|
>>> collections.__cached__
|
|
'c:/py32/lib/__pycache__/collections.cpython-32.pyc'
|
|
|
|
* The tag that is unique to each interpreter is accessible from the :mod:`imp`
|
|
module:
|
|
|
|
>>> import imp
|
|
>>> imp.get_tag()
|
|
'cpython-32'
|
|
|
|
* Scripts that try to deduce source filename from the imported file now need to
|
|
be smarter. It is no longer sufficient to simply strip the "c" from a ".pyc"
|
|
filename. Instead, use the new functions in the :mod:`imp` module:
|
|
|
|
>>> imp.source_from_cache('c:/py32/lib/__pycache__/collections.cpython-32.pyc')
|
|
'c:/py32/lib/collections.py'
|
|
>>> imp.cache_from_source('c:/py32/lib/collections.py')
|
|
'c:/py32/lib/__pycache__/collections.cpython-32.pyc'
|
|
|
|
* The :mod:`py_compile` and :mod:`compileall` modules have been updated to
|
|
reflect the new naming convention and target directory.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`3147` - PYC Repository Directories
|
|
PEP written by Barry Warsaw.
|
|
|
|
|
|
PEP 3149 ABI Version Tagged .so Files
|
|
=====================================
|
|
|
|
The PYC repository directory allows multiple bytecode cache files to be
|
|
co-located. This PEP implements a similar mechanism for shared object files by
|
|
giving them a common directory and distinct names for each version.
|
|
|
|
The common directory is "pyshared" and the file names are made distinct by
|
|
identifying the Python implementation (such as CPython, PyPy, Jython, etc.), the
|
|
major and minor version numbers, and optional build flags (such as "d" for
|
|
debug, "m" for pymalloc, "u" for wide-unicode). For an arbitrary package "foo",
|
|
you may see these files when the distribution package is installed::
|
|
|
|
/usr/share/pyshared/foo.cpython-32m.so
|
|
/usr/share/pyshared/foo.cpython-33md.so
|
|
|
|
In Python itself, the tags are accessible from functions in the :mod:`sysconfig`
|
|
module::
|
|
|
|
>>> import sysconfig
|
|
>>> sysconfig.get_config_var('SOABI') # find the version tag
|
|
'cpython-32mu'
|
|
>>> sysconfig.get_config_var('SO') # find the full filename extension
|
|
'cpython-32mu.so'
|
|
|
|
.. seealso::
|
|
|
|
:pep:`3149` - ABI Version Tagged .so Files
|
|
PEP written by Barry Warsaw.
|
|
|
|
|
|
Email 5.1
|
|
=========
|
|
|
|
The email package is extended to be able to parse and generate email messages
|
|
in bytes format.
|
|
|
|
* New functions :func:`~email.message_from_bytes` and
|
|
:func:`~email.message_from_binary_file`, and new classes
|
|
:class:`~email.parser.BytesFeedParser` and :class:`~email.parser.BytesParser`
|
|
allow binary message data to be parsed into model objects.
|
|
|
|
* Given bytes input to the model, :meth:`~email.message.Message.get_payload`
|
|
will by default decode a message body that has a
|
|
:mailheader:`Content-Transfer-Encoding` of ``8bit`` using the charset
|
|
specified in the MIME headers and return the resulting string.
|
|
|
|
* Given bytes input to the model, :class:`~email.generator.Generator` will
|
|
convert message bodies that have a :mailheader:`Content-Transfer-Encoding` of
|
|
8bit to instead have a 7bit Content-Transfer-Encoding.
|
|
|
|
* New class :class:`~email.generator.BytesGenerator` produces bytes
|
|
as output, preserving any unchanged non-ASCII data that was
|
|
present in the input used to build the model, including message bodies
|
|
with a :mailheader:`Content-Transfer-Encoding` of 8bit.
|
|
|
|
(Proposed and implemented by R. David Murray, :issue:`4661`.)
|
|
|
|
|
|
Other Language Changes
|
|
======================
|
|
|
|
Some smaller changes made to the core Python language are:
|
|
|
|
* The :func:`hasattr` function used to catch and suppress any Exception. Now,
|
|
it only catches :exc:`AttributeError`. Under the hood, :func:`hasattr` works
|
|
by calling :func:`getattr` and throwing away the results. This is necessary
|
|
because dynamic attribute creation is possible using :meth:`__getattribute__`
|
|
or :meth:`__getattr__`. If :func:`hasattr` were to just scan instance and class
|
|
dictionaries it would miss the dynamic methods and make it difficult to
|
|
implement proxy objects.
|
|
|
|
(Discovered by Yury Selivanov and fixed by Benjamin Peterson; :issue:`9666`.)
|
|
|
|
* The :func:`str` of a float or complex number is now the same as its
|
|
:func:`repr`. Previously, the :func:`str` form was shorter but that just
|
|
caused confusion and is no longer needed now that the shortest possible
|
|
:func:`repr` is displayed by default:
|
|
|
|
>>> repr(math.pi)
|
|
'3.141592653589793'
|
|
>>> str(math.pi)
|
|
'3.141592653589793'
|
|
|
|
(Proposed and implemented by Mark Dickinson; :issue:`9337`.)
|
|
|
|
* :class:`memoryview` objects now have a :meth:`release()` method and support
|
|
the context manager protocol. This allows timely release of any resources
|
|
that were acquired when requesting a buffer from the original object.
|
|
|
|
(Added by Antoine Pitrou; :issue:`9757`.)
|
|
|
|
* Mark Dickinson crafted an elegant and efficient scheme for assuring that
|
|
different numeric datatypes will have the same hash value whenever their
|
|
actual values are equal::
|
|
|
|
>>> assert hash(Fraction(3, 2)) == hash(1.5) == \
|
|
hash(Decimal("1.5")) == hash(complex(1.5, 0))
|
|
|
|
(See :issue:`8188`.)
|
|
|
|
* Previously it was illegal to delete a name from the local namespace if it
|
|
occurs as a free variable in a nested block::
|
|
|
|
>>> def outer(x):
|
|
... def inner():
|
|
... return x
|
|
... inner()
|
|
... del x
|
|
|
|
This is now allowed. Remember that the target of an :keyword:`except` clause
|
|
is cleared, so this code which used to work with Python 2.6, raised a
|
|
:exc:`SyntaxError` with Python 3.1 and now works again::
|
|
|
|
>>> def f():
|
|
... def print_error():
|
|
... print(e)
|
|
... try:
|
|
... something
|
|
... except Exception as e:
|
|
... print_error()
|
|
... # implicit "del e" here
|
|
|
|
(See :issue:`4617`.)
|
|
|
|
* A new warning category, :exc:`ResourceWarning`, has been added. It is
|
|
emitted when certain potential issues with resource consumption or cleanup
|
|
are detected. It is silenced by default in normal release builds, but
|
|
can be easily enabled through the means provided by the :mod:`warnings`
|
|
module, or on the command line.
|
|
|
|
:exc:`ResourceWarning` is issued at interpreter shutdown if the
|
|
:data:`gc.garbage` list isn't empty. This is meant to make the programmer
|
|
aware that their code contains object finalization issues.
|
|
|
|
(Added by Antoine Pitrou and Georg Brandl; :issue:`477863`.)
|
|
|
|
:exc:`ResourceWarning` is also issued when a :term:`file object` is destroyed
|
|
without having been explicitly closed. While the deallocator for such
|
|
object ensures it closes the underlying operating system resource
|
|
(usually, a file descriptor), the delay in deallocating the object could
|
|
produce various issues, especially under Windows. Here is an example
|
|
of enabling the warning from the command line::
|
|
|
|
$ ./python -Wdefault
|
|
Python 3.2a3+ (py3k, Nov 5 2010, 22:58:04)
|
|
[GCC 4.4.3] on linux2
|
|
Type "help", "copyright", "credits" or "license" for more information.
|
|
>>> f = open("foo", "wb")
|
|
>>> del f
|
|
__main__:1: ResourceWarning: unclosed file <_io.BufferedWriter name='foo'>
|
|
>>>
|
|
|
|
(Added by Antoine Pitrou, :issue:`10093`.)
|
|
|
|
.. XXX: Issues #9213 and #2690 make the objects returned by range()
|
|
more sequence like in accordance with their registration as
|
|
implementing the Sequence ABC
|
|
|
|
|
|
New, Improved, and Deprecated Modules
|
|
=====================================
|
|
|
|
* XXX mention :mod:`argparse`.
|
|
|
|
* The :mod:`functools` module includes a new decorator for caching function
|
|
calls. :func:`functools.lru_cache` can save repeated queries to an external
|
|
resource whenever the results are expected to be the same.
|
|
|
|
For example, adding a caching decorator to a database query function can save
|
|
database accesses for popular searches::
|
|
|
|
@functools.lru_cache(maxsize=300)
|
|
def get_phone_number(name):
|
|
c = conn.cursor()
|
|
c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,))
|
|
return c.fetchone()[0]
|
|
|
|
>>> for name in user_requests:
|
|
... get_phone_number(name) # cached lookup
|
|
|
|
To help with choosing an effective cache size, the wrapped function is
|
|
instrumented for tracking cache statistics:
|
|
|
|
>>> get_phone_number.cache_info()
|
|
CacheInfo(hits=4805, misses=980, maxsize=300, currsize=300)
|
|
|
|
If the phonelist table gets updated, the outdated contents of the cache can be
|
|
cleared with:
|
|
|
|
>>> get_phone_number.cache_clear()
|
|
|
|
(Contributed by Raymond Hettinger.)
|
|
|
|
* The :func:`functools.wraps` decorator now adds a :attr:`__wrapped__` attribute
|
|
pointing to the original callable function. This allows wrapped functions to
|
|
be introspected. It also copies :attr:`__annotations__` if defined. And now
|
|
it also gracefully skips over missing attributes such as :attr:`__doc__` which
|
|
might not be defined for the wrapped callable.
|
|
|
|
(By Nick Coghlan and Terrence Cole; :issue:`9567`, :issue:`3445`, and
|
|
:issue:`8814`.)
|
|
|
|
* The :mod:`nntplib` module gets a revamped implementation with better
|
|
bytes / unicode semantics as well as more practical APIs. These improvements
|
|
break compatibility with the nntplib version in Python 3.1, which was
|
|
partly dysfunctional in itself.
|
|
|
|
(Contributed by Antoine Pitrou in :issue:`9360`)
|
|
|
|
* The :mod:`abc` module now supports :func:`~abc.abstractclassmethod` and
|
|
:func:`~abc.abstractstaticmethod`.
|
|
|
|
(Patch submitted by Daniel Urban; :issue:`5867`.)
|
|
|
|
* The previously deprecated :func:`contextlib.nested` function has been removed
|
|
in favor of a plain :keyword:`with` statement which can accept multiple
|
|
context managers. The latter technique is faster (because it is built-in),
|
|
and it does a better job finalizing multiple context managers when one of them
|
|
raises an exception.
|
|
|
|
(Contributed by Georg Brandl and Mattias Brändström;
|
|
`appspot issue 53094 <http://codereview.appspot.com/53094>`_.)
|
|
|
|
* The :class:`ftplib.FTP` class now supports the context manager protocol to
|
|
unconditionally consume :exc:`socket.error` exceptions and to close the FTP
|
|
connection when done::
|
|
|
|
>>> from ftplib import FTP
|
|
>>> with FTP("ftp1.at.proftpd.org") as ftp:
|
|
... ftp.login()
|
|
... ftp.dir()
|
|
...
|
|
'230 Anonymous login ok, restrictions apply.'
|
|
dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .
|
|
dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 ..
|
|
dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS
|
|
dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora
|
|
|
|
Other file-like objects such as :class:`mmap.mmap` and :func:`fileinput.input`
|
|
also grew auto-closing context managers::
|
|
|
|
with fileinput.input(files=('log1.txt', 'log2.txt')) as f:
|
|
for line in f:
|
|
process(line)
|
|
|
|
(Contributed by Tarek Ziadé and Giampaolo Rodolà in :issue:`4972`, and
|
|
by Georg Brandl in :issue:`8046` and :issue:`1286`.)
|
|
|
|
* :class:`gzip.GzipFile` now implements the :class:`io.BufferedIOBase` ABC
|
|
(except for ``truncate()``), has a :meth:`~gzip.GzipFile.peek` method,
|
|
and supports unseekable as well as zero-padded file objects.
|
|
|
|
(Contributed by Antoine Pitrou, Nir Aides and Brian Curtin in :issue:`9962`,
|
|
:issue:`1675951`, :issue:`7471` and :issue:`2846`.)
|
|
|
|
The :mod:`gzip` module also gains the :func:`~gzip.compress` and
|
|
:func:`~gzip.decompress` functions for easier in-memory compression and
|
|
decompression.
|
|
|
|
(Contributed by Anand B. Pillai in :issue:`3488`.)
|
|
|
|
* The :mod:`os` module now has the :const:`ST_RDONLY` and :const:`ST_NOSUID`
|
|
constants, for use with the :func:`~os.statvfs` function.
|
|
|
|
(Patch by Adam Jackson; :issue:`7647`.)
|
|
|
|
* :func:`os.getppid` is now supported on Windows. Note that it will continue to
|
|
return the same pid even after the parent process has exited.
|
|
|
|
(Patch by Jon Anglin; :issue:`6394`.)
|
|
|
|
* The :func:`shutil.copytree` function has two new options:
|
|
|
|
* *ignore_dangling_symlinks*: when ``symlinks=False`` so that the function
|
|
copies the file pointed to by the symlink, not the symlink itself. This
|
|
option will silence the error raised if the file doesn't exist.
|
|
|
|
* *copy_function*: is a callable that will be used to copy files.
|
|
:func:`shutil.copy2` is used by default.
|
|
|
|
(Contributed by Tarek Ziadé.)
|
|
|
|
* Socket objects now have a :meth:`~socket.socket.detach()` method which puts
|
|
the socket into closed state without actually closing the underlying file
|
|
descriptor. The latter can then be reused for other purposes.
|
|
|
|
(Added by Antoine Pitrou; :issue:`8524`.)
|
|
|
|
* The :mod:`sqlite3` module has two new capabilities.
|
|
|
|
The :attr:`Connection.in_transit` attribute is true if there is an active
|
|
transaction for uncommitted changes.
|
|
|
|
The :meth:`Connection.enable_load_extension` and
|
|
:meth:`Connection.load_extension` methods allows you to load SQLite extensions
|
|
from ".so" files. One well-known extension is the fulltext-search extension
|
|
distributed with SQLite.
|
|
|
|
(Contributed by R. David Murray and Shashwat Anand; :issue:`8845`.)
|
|
|
|
* The :mod:`ssl` module has a new class, :class:`~ssl.SSLContext` which serves
|
|
as a container for various persistent SSL data, such as protocol settings,
|
|
certificates, private keys, and various other options. The
|
|
:meth:`~ssl.SSLContext.wrap_socket` method allows to create an SSL socket from
|
|
such an SSL context. (Added by Antoine Pitrou; :issue:`8550`.)
|
|
|
|
A new function, :func:`ssl.match_hostname`, helps implement server identity
|
|
verification for higher-level protocols by implementing the rules of
|
|
HTTPS (from :rfc:`2818`), which are also suitable for other protocols.
|
|
(Added by Antoine Pitrou, :issue:`1589`).
|
|
|
|
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`.)
|
|
|
|
When linked against a recent enough version of OpenSSL, the :mod:`ssl`
|
|
module now supports the Server Name Indication extension to the TLS
|
|
protocol, allowing for several "virtual hosts" using different certificates
|
|
on a single IP/port. This extension is only supported in client mode,
|
|
and is activated by passing the *server_hostname* argument to
|
|
:meth:`SSLContext.wrap_socket`.
|
|
(Added by Antoine Pitrou, :issue:`5639`.)
|
|
|
|
Various options have been added to the :mod:`ssl` module, such as
|
|
:data:`~ssl.OP_NO_SSLv2` which allows to force disabling of the insecure and
|
|
obsolete SSLv2 protocol. (Added by Antoine Pitrou; :issue:`4870`.)
|
|
|
|
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`.)
|
|
|
|
* :class:`http.client.HTTPSConnection`, :class:`urllib.request.HTTPSHandler`
|
|
and :func:`urllib.request.urlopen` now take optional arguments to allow for
|
|
server certificate checking against a set of Certificate Authorities,
|
|
as recommended in public uses of HTTPS.
|
|
(Added by Antoine Pitrou, :issue:`9003`.)
|
|
|
|
* Instances of :class:`unittest.TestCase` have two new methods
|
|
:meth:`~unittest.TestCase.assertWarns` and :meth:`~unittest.TestCase.assertWarnsRegexp`
|
|
to check that a given warning type was triggered by the code under test::
|
|
|
|
with self.assertWarns(DeprecationWarning):
|
|
legacy_function('XYZ')
|
|
|
|
* The following :class:`unittest.TestCase` methods are now deprecated:
|
|
* :meth:`assert_` (use :meth:`.assertTrue` instead);
|
|
* :meth:`assertEquals` (use :meth:`.assertEqual` instead);
|
|
* :meth:`assertNotEquals` (use :meth:`.assertNotEqual` instead);
|
|
* :meth:`assertAlmostEquals` (use :meth:`.assertAlmostEqual` instead);
|
|
* :meth:`assertNotAlmostEquals` (use :meth:`.assertNotAlmostEqual` instead);
|
|
|
|
The ``TestCase.fail*`` methods deprecated in Python 3.1 will be removed in
|
|
Python 3.3. See also the :ref:`deprecated-aliases` section in the
|
|
:mod:`unittest` documentation.
|
|
|
|
(Contributed by Ezio Melotti; :issue:`9424`.)
|
|
|
|
* The previously deprecated :func:`string.maketrans` function has been removed
|
|
in favor of the static methods, :meth:`bytes.maketrans` and
|
|
:meth:`bytearray.maketrans`. This change solves the confusion around which
|
|
types were supported by the :mod:`string` module. Now, :class:`str`,
|
|
:class:`bytes`, and :class:`bytearray` each have their own **maketrans** and
|
|
**translate** methods with intermediate translation tables of the appropriate
|
|
type.
|
|
|
|
(Contributed by Georg Brandl; :issue:`5675`.)
|
|
|
|
* :class:`~poplib.POP3_SSL` class now accepts a *context* parameter, which is a
|
|
:class:`ssl.SSLContext` object allowing bundling SSL configuration options,
|
|
certificates and private keys into a single (potentially long-lived)
|
|
structure.
|
|
|
|
(Contributed by Giampaolo Rodolà; :issue:`8807`.)
|
|
|
|
* :func:`socket.create_connection` now supports the context manager protocol
|
|
to unconditionally consume :exc:`socket.error` exceptions and to close the
|
|
socket when done.
|
|
|
|
(Contributed by Giampaolo Rodolà; :issue:`9794`.)
|
|
|
|
* :class:`asyncore.dispatcher` now provides a
|
|
:meth:`~asyncore.dispatcher.handle_accepted()` method
|
|
returning a `(sock, addr)` pair which is called when a connection has actually
|
|
been established with a new remote endpoint. This is supposed to be used as a
|
|
replacement for old :meth:`~asyncore.dispatcher.handle_accept()` and avoids
|
|
the user to call :meth:`~asyncore.dispatcher.accept()` directly.
|
|
|
|
(Contributed by Giampaolo Rodolà; :issue:`6706`.)
|
|
|
|
* The :mod:`tempfile` module has a new context manager,
|
|
:class:`~tempfile.TemporaryDirectory` which provides easy deterministic
|
|
cleanup of temporary directories.
|
|
|
|
(Contributed by Neil Schemenauer and Nick Coghlan; :issue:`5178`.)
|
|
|
|
* The :mod:`smtplib` :class:`~smtplib.SMTP` class now accepts a byte string
|
|
for the *msg* argument to the :meth:`~smtplib.SMTP.sendmail` method,
|
|
and a new method, :meth:`~smtplib.SMTP.send_message` accepts a
|
|
:class:`~email.message.Message` object and can optionally obtain the
|
|
*from_addr* and *to_addrs* addresses directly from the object.
|
|
|
|
(Contributed by R. David Murray, :issue:`10321`.)
|
|
|
|
* The :mod:`inspect` module has a new function :func:`getgenatorstate`
|
|
to easily identify the current state of a generator as one of
|
|
``GEN_CREATED``, ``GEN_RUNNING``, ``GEN_SUSPENDED`` or ``GEN_CLOSED``.
|
|
|
|
(Contributed by Rodolpho Eckhardt and Nick Coghlan, :issue:`10220`.)
|
|
|
|
.. XXX: Mention inspect.getattr_static (Michael Foord)
|
|
.. XXX: Mention urllib.parse changes
|
|
Issue 9873 (Nick Coghlan):
|
|
- ASCII byte sequence support in URL parsing
|
|
- named tuple for urldefrag return value
|
|
Issue 5468 (Dan Mahn) for urlencode:
|
|
- bytes input support
|
|
- non-UTF8 percent encoding of non-ASCII characters
|
|
Issue 2987 for IPv6 (RFC2732) support in urlparse
|
|
|
|
* The :mod:`pydoc` module now provides a much improved Web server interface,
|
|
as well as a new command-line option to automatically open a browser
|
|
window to display that server.
|
|
|
|
(Contributed by Ron Adam; :issue:`2001`.)
|
|
|
|
Multi-threading
|
|
===============
|
|
|
|
* The mechanism for serializing execution of concurrently running Python threads
|
|
(generally known as the GIL or Global Interpreter Lock) has been rewritten.
|
|
Among the objectives were more predictable switching intervals and reduced
|
|
overhead due to lock contention and the number of ensuing system calls. The
|
|
notion of a "check interval" to allow thread switches has been abandoned and
|
|
replaced by an absolute duration expressed in seconds. This parameter is
|
|
tunable through :func:`sys.setswitchinterval()`. It currently defaults to 5
|
|
milliseconds.
|
|
|
|
Additional details about the implementation can be read from a `python-dev
|
|
mailing-list message
|
|
<http://mail.python.org/pipermail/python-dev/2009-October/093321.html>`_
|
|
(however, "priority requests" as exposed in this message have not been kept
|
|
for inclusion).
|
|
|
|
(Contributed by Antoine Pitrou.)
|
|
|
|
* Recursive locks (created with the :func:`threading.RLock` API) now benefit
|
|
from a C implementation which makes them as fast as regular locks, and between
|
|
10x and 15x faster than their previous pure Python implementation.
|
|
|
|
(Contributed by Antoine Pitrou; :issue:`3001`.)
|
|
|
|
* Regular and recursive locks now accept an optional *timeout* argument to their
|
|
:meth:`acquire` method. (Contributed by Antoine Pitrou; :issue:`7316`.)
|
|
|
|
Similarly, :meth:`threading.Semaphore.acquire` also gains a *timeout*
|
|
argument. (Contributed by Torsten Landschoff; :issue:`850728`.)
|
|
|
|
|
|
Optimizations
|
|
=============
|
|
|
|
A number of small performance enhancements have been added:
|
|
|
|
* JSON decoding performance is improved and memory consumption is reduced
|
|
whenever the same string is repeated for multiple keys.
|
|
|
|
(Contributed by Antoine Pitrou; :issue:`7451`.)
|
|
|
|
* JSON encoding now uses the C speedups also when the ``sort_keys`` argument
|
|
is true.
|
|
|
|
(Contributed by Raymond Hettinger and Antoine Pitrou, :issue:`10314`.)
|
|
|
|
* Python's peephole optimizer now recognizes patterns such ``x in {1, 2, 3}`` as
|
|
being a test for membership in a set of constants. The optimizer recasts the
|
|
:class:`set` as a :class:`frozenset` and stores the pre-built constant.
|
|
|
|
Now that the speed penalty is gone, it is practical to start writing
|
|
membership tests using set-notation. This style is both semantically clear
|
|
and operationally fast::
|
|
|
|
extension = name.rpartition('.')[2]
|
|
if extension in {'xml', 'html', 'xhtml', 'css'}:
|
|
handle(name)
|
|
|
|
(Patch and additional tests by Dave Malcolm; :issue:`6690`).
|
|
|
|
* The fast-search algorithm in stringlib is now used by the :meth:`split`,
|
|
:meth:`rsplit`, :meth:`splitlines` and :meth:`replace` methods on
|
|
:class:`bytes`, :class:`bytearray` and :class:`str` objects. Likewise, the
|
|
algorithm is also used by :meth:`rfind`, :meth:`rindex`, :meth:`rsplit` and
|
|
:meth:`rpartition`.
|
|
|
|
(Patch by Florent Xicluna in :issue:`7622` and :issue:`7462`.)
|
|
|
|
* Serializing and unserializing data using the :mod:`pickle` module is now
|
|
several times faster. (Contributed by Alexandre Vassalotti, Antoine Pitrou
|
|
and the Unladen Swallow team in :issue:`9410` and :issue:`3873`.)
|
|
|
|
|
|
Unicode
|
|
=======
|
|
|
|
Python has been updated to Unicode 6.0.0. The new features of the
|
|
Unicode Standard that will affect Python users include:
|
|
|
|
* adds 2,088 characters, including over 1,000 additional symbols—chief
|
|
among them the additional emoji symbols, which are especially
|
|
important for mobile phones;
|
|
|
|
* corrects character properties for existing characters including
|
|
|
|
- a general category change to two Kannada characters (U+0CF1,
|
|
U+0CF2), which has the effect of making them newly eligible for
|
|
inclusion in identifiers;
|
|
|
|
- a general category change to one New Tai Lue numeric character
|
|
(U+19DA), which would have the effect of disqualifying it from
|
|
inclusion in identifiers unless grandfathering measures are in place
|
|
for the defining identifier syntax.
|
|
|
|
The :mod:`os` module has two new functions: :func:`~os.fsencode` and
|
|
:func:`~os.fsdecode`. Add :data:`os.environb`: bytes version of
|
|
:data:`os.environ`, :func:`os.getenvb` function and
|
|
:data:`os.supports_bytes_environ` constant.
|
|
|
|
``'mbcs'`` encoding doesn't ignore the error handler argument any more. By
|
|
default (strict mode), it raises an UnicodeDecodeError on undecodable byte
|
|
sequence and UnicodeEncodeError on unencodable character. To get the ``'mbcs'``
|
|
encoding of Python 3.1, use ``'ignore'`` error handler to decode and
|
|
``'replace'`` error handler to encode. ``'mbcs'`` supports ``'strict'`` and
|
|
``'ignore'`` error handlers for decoding, and ``'strict'`` and ``'replace'``
|
|
for encoding.
|
|
|
|
On Mac OS X, Python uses ``'utf-8'`` to decode the command line arguments,
|
|
instead of the locale encoding (which is ISO-8859-1 if the ``LANG`` environment
|
|
variable is not set).
|
|
|
|
By default, tarfile uses ``'utf-8'`` encoding on Windows (instead of
|
|
``'mbcs'``), and the ``'surrogateescape'`` error handler on all operating
|
|
systems.
|
|
|
|
|
|
.. IDLE
|
|
====
|
|
|
|
* Stub
|
|
|
|
|
|
Build and C API Changes
|
|
=======================
|
|
|
|
Changes to Python's build process and to the C API include:
|
|
|
|
* The C functions that access the Unicode Database now accept and return
|
|
characters from the full Unicode range, even on narrow unicode builds
|
|
(Py_UNICODE_TOLOWER, Py_UNICODE_ISDECIMAL, and others). A visible difference
|
|
in Python is that :func:`unicodedata.numeric` now returns the correct value
|
|
for large code points, and :func:`repr` may consider more characters as
|
|
printable.
|
|
|
|
(Reported by Bupjoe Lee and fixed by Amaury Forgeot D'Arc; :issue:`5127`.)
|
|
|
|
* Computed gotos are now enabled by default on supported compilers (which are
|
|
detected by the configure script). They can still be disabled selectively by
|
|
specifying ``--without-computed-gotos``.
|
|
|
|
(Contributed by Antoine Pitrou; :issue:`9203`.)
|
|
|
|
* The option ``--with-wctype-functions`` was removed. The built-in unicode
|
|
database is now used for all functions.
|
|
|
|
(Contributed by Amaury Forgeot D'Arc; :issue:`9210`.)
|
|
|
|
* Hash values are now values of a new type, Py_hash_t, which is defined to
|
|
be the same size as a pointer. Previously they were of type long, which
|
|
on some 64-bit operating systems is still only 32 bits long.
|
|
|
|
(Contributed by Benjamin Peterson; :issue:`9778`.)
|
|
|
|
|
|
Porting to Python 3.2
|
|
=====================
|
|
|
|
This section lists previously described changes and other bugfixes that may
|
|
require changes to your code:
|
|
|
|
* The :mod:`nntplib` module was reworked extensively, meaning that its APIs
|
|
are often incompatible with the 3.1 APIs.
|
|
|
|
* :class:`bytearray` objects cannot be used any more as filenames: convert them
|
|
to :class:`bytes`.
|
|
|
|
* PyArg_Parse*() functions:
|
|
|
|
* "t#" format has been removed: use "s#" or "s*" instead
|
|
* "w" and "w#" formats has been removed: use "w*" instead
|
|
|
|
* The :c:type:`PyCObject` type, deprecated in 3.1, has been removed. To wrap
|
|
opaque C pointers in Python objects, the :c:type:`PyCapsule` API should be used
|
|
instead; the new type has a well-defined interface for passing typing safety
|
|
information and a less complicated signature for calling a destructor.
|
|
|
|
* Remove sys.setfilesystemencoding() function: it was broken by design.
|