At the moment

./python -q
>>> import sys; sys.version
'3.3.0a1+'
...
./python3.2
'3.2.3rc1'
...
./python2.7
'3.2.3rc1'

• New faulthandler module.

This module contains functions to dump Python tracebacks explicitly, on a fault, after a timeout, or on a user signal. Call faulthandler.enable() to install fault handlers for the SIGSEGV, SIGFPE, SIGABRT, SIGBUS, and SIGILL signals.

• It is version 3.3 and was contributed by Victor Stinner.

http://blog.python.org/2011/05/new-faulthandler-module-in-python-33.html

• The newly-added lzma module provides data compression and decompression using the LZMA algorithm, including support for the .xz and .lzma file formats.

• lzma compression is usually better than bz2.

• Per Øyvind Karlsen, Nadeem Vawda and others.

• http://en.wikipedia.org/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm

• http://bugs.python.org/issue6715

• http://docs.python.org/dev/library/lzma.html#examples

• bz2.BZ2File can now read from and write to arbitrary file-like objects, by means of its constructor’s fileobj argument. (Nadeem Vawda)

• bz2.BZ2File and bz2.decompress() can now decompress multi-stream inputs. bz2.BZ2File can now also be used to create this type of file, using the 'a' (append) mode. (Nir Aides)

• http://bugs.python.org/issue5863

• http://bugs.python.org/issue1625

• Behavior is similar to bunzip2 utility. Like gzip, you can concatenate two bzip2 files.

• bzip2 -c /etc/passwd >/tmp/pass.bz2

• bzip2 -c /etc/passwd >>/tmp/pass.bz2

• bunzip2 will output both parts, generating two copies of the file.

• So nothing needs to be done on compression, but uncompression needs to look for another chunk of compressed data after finishing one chunk.

• sendfile() function which provides an efficent “zero-copy” way for copying data from one file (or socket) descriptor to another. ( Ross Lagerwall and Giampaolo Rodola')

• Use of sendfile instead of send provides 1.5x speed up!

• fwalk() function similar to walk() except that it also yields file descriptors referring to the directories visited. (Interesting!)

• Since 3.2 - The os module provides two new functions, fsencode() and fsdecode(), for encoding and decoding filenames based on file-system encoding.

• http://code.google.com/p/pyftpdlib/issues/detail?id=152#c5

• distutils module is called packaging, helper functions for building, packaging, distributing and installing additional projects into a Python installation.

• distutils is still provided in the standard library, but users are encouraged to transition to packaging.

• New features from packaging will be available under distutils2 in PyPI.

http://docs.python.org/dev/library/packaging.html#module-packaging

• signal.signal() and signal.siginterrupt() raise an OSError, instead of a RuntimeError: OSError has an errno attribute.

• signal module has functions such as pthread_sigmask , pthread_kill, sigpending, sigwait, sigwaitinfo.

• Jean-Paul Calderone, Antoine Pitrou and others.

http://docs.python.org/dev/library/signal.html man sigprocmask man pthread_sigmask man sigwait man sigwaitinfo

• The socket class now supports the PF_CAN protocol family. (Matthias Fuchs, Tiago Gonçalves) - Control Area Network Bus Drivers.

• The socket class now supports the PF_RDS protocol family - Reliable High performance, low latency reliable connectioness protocol for delivering datagrams.

• RAND_bytes(): generate cryptographically strong pseudo-random bytes.

• RAND_pseudo_bytes(): generate pseudo-random bytes. (Both by Victor Stinner)

• Query the SSL compression algorithm used by an SSL socket, thanks to its new compression() method. You can also supress Compression. ( Antoine Pitrou)

• http://bugs.python.org/issue13634

• The sys module has a new thread_info struct sequence holding informations about the thread implementation.

>>> sys.thread_info
sys.thread_info(name='pthread', lock='semaphore', version='NPTL 2.13')

• The Request class, now accepts a method argument used by get_method() to determine what HTTP method should be used. For example, this will send a 'HEAD' request.

>>> urlopen(Request('http://www.python.org', method='HEAD'))

• The parse.urlparse() function now supports IPv6 addresses as described in RFC 2732

• request.urlopen can take POST which can be an iterable.

• http.client.HTTPSConnection, urllib.request.HTTPSHandler and 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.

• argparse will be the future and optparse will slowly be deprecated.

• Support for positional args, sub-commands, 'required options', pattern for specifying and validating options.

• argparse has the ability to define subparsers, each with their own argument patterns and help displays:

import argparse

parser = argparse.ArgumentParser(
            description = 'Manage servers',         # main description for help
            epilog = 'Tested on Solaris and Linux') # displayed after help
parser.add_argument('action',                       # argument name
            choices = ['deploy', 'start', 'stop'],  # three allowed values
            help = 'action on each target')         # help msg
parser.add_argument('targets',
            metavar = 'HOSTNAME',                   # var name used in help msg
            nargs = '+',                            # require one or more targets
            help = 'url for target machines')       # help msg explanation
parser.add_argument('-u', '--user',                 # -u or --user option
            required = True,                        # make it a required argument
            help = 'login as user')

print(parser.parse_args('-h'.split()))

• The logging documentation has been augmented by a basic tutorial, an advanced tutorial, and a cookbook of logging recipes.

• logging.config.dictConfig() - logging configuration with plain Python dictionaries.

with open('conf.json', 'r') as f:
        conf = json.load(f)
logging.config.dictConfig(conf)

• Code for creating and managing concurrency is being collected in a new top-level namespace, concurrent

• first package is futures high level interface for managing threads and processes.

• Inspired by java.utils.concurrent and Future Object.

• status checks (running or done), timeouts, cancellations, adding callbacks, and access to results or exceptions

The primary offering of the new module is a pair of executor classes
for launching and managing calls. The goal of the executors is to make
it easier to use existing tools for making parallel calls. They save
the effort needed to setup a pool of resources, launch the calls,
create a results queue, add time-out handling, and limit the total
number of threads, processes, or remote procedure calls.

Ideally, each application should share a single executor across
multiple components so that process and thread limits can be centrally
managed. This solves the design challenge that arises when each
component has its own competing strategy for resource management.

Both classes share a common interface with three methods: submit() for
scheduling a callable and returning a Future object; map() for
scheduling many asynchronous calls at a time, and shutdown() for
freeing resources. The class is a context manager and can be used in a
with statement to assure that resources are automatically released when
currently pending futures are done executing.

• The functools module includes a new decorator for caching function calls. functools.lru_cache() can save repeated queries to an external resource whenever the results are expected to be the same.

>>> import functools
>>> @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]
...
>>> get_phone_number(name)        # cached lookup

• We have cache stats

>>> get_phone_number.cache_info()
CacheInfo(hits=4805, misses=980, maxsize=300, currsize=300)

• OMG! Way to get unwrapped function.

>>> get_phone_number = get_phone_number.__wrapped__    # uncached function

• functools.total_ordering - rich comparison methods, a new decorator functools.total_ordering() will use a existing equality and inequality methods to fill in the remaining methods.

@total_ordering
class Student:
    def __eq__(self, other):
        return ((self.lastname.lower(), self.firstname.lower()) ==
                (other.lastname.lower(), other.firstname.lower()))
    def __lt__(self, other):
        return ((self.lastname.lower(), self.firstname.lower()) <
                (other.lastname.lower(), other.firstname.lower()))

• Magic happens.

>>> from itertools import accumulate
>>> list(accumulate([8, 2, 50]))
[8, 10, 60]

• The collections.Counter class now has two forms of in-place subtraction, the existing -= operator for saturating subtraction and the new subtract() method for regular subtraction

• http://en.wikipedia.org/wiki/Saturation_arithmetic If the result of an operation is greater than the maximum it is set ("clamped") to the maximum, while if it is below the minimum it is clamped to the minimum.

• All these features were added by Raymond Hettinger

>>> tally = Counter(dogs=5, cat=3)
>>> tally -= Counter(dogs=2, cats=8)    # saturating subtraction
>>> tally
Counter({'dogs': 3})

>>> tally = Counter(dogs=5, cats=3)
>>> tally.subtract(dogs=2, cats=8)      # regular subtraction
>>> tally
Counter({'dogs': 3, 'cats': -5})

• improvements supporting test discovery for packages, easier experimentation at the interactive prompt

python -m unittest discover -s my_proj_dir -p _test.py

• Interactivity!

>>> TestCase().assertEqual(pow(2, 3), 8)

• 3.2 onwards

• Multiple implementations can refer to their own .pyc files.

• mymodule.cpython-32.pyc, mymodule.cpython-33.pyc, and mymodule.unladen10.pyc

• pyc files are now collected in a __pycache__ directory stored under the package directory

• Imported modules now have a __cached__ attribute which stores the name of the actual file that was imported

• tag that is unique to each interpreter is accessible from the imp module

• Well Intentioned Upgrade for WSGI to support Python3.

• Informational PEP clarifies how bytes/text issues are to be handled by the WGSI protocol

• str.format_map

• It can take dictionaries from defaultdict, shelve, ConfigParser, dbm.

>>> import shelve
>>> d = shelve.open('tmp.shl')
>>> 'The {project_name} status is {status} as of {date}'.format_map(d)
'The testing project status is green as of February 15, 2011'

>>> class PlaceholderDict(dict):
        def __missing__(self, key):
            return '<{}>'.format(key)
>>> 'Hello {name}, welcome to {location}'.format_map(PlaceholderDict())
'Hello <name>, welcome to <location>'

• The threading module has a new Barrier synchronization class for making multiple threads wait until all of them have reached a common barrier point.

from threading import Barrier, Thread

def get_votes(site):
    ballots = conduct_election(site)
    all_polls_closed.wait()        # do not count until all polls are closed
    totals = summarize(ballots)
    publish(site, totals)

all_polls_closed = Barrier(len(sites))
for site in sites:
    Thread(target=get_votes, args=(site,)).start()

• The ast.literal_eval() function serves as a secure alternative to the builtin eval() function which is easily abused.

>>> from ast import literal_eval
>>> request = "{'req': 3, 'func': 'pow', 'args': (2, 0.5)}"
>>> literal_eval(request)
{'args': (2, 0.5), 'req': 3, 'func': 'pow'}

>>> request = "os.system('do something harmful')"
>>> literal_eval(request)
Traceback (most recent call last):
  ...
ValueError: malformed node or string: <_ast.Call object at 0x101739a10>

• array module takes long long type.

• shutil.disk_usage() - total, used and free disk space statistics.

• DeprecationWarning and its descendants are now ignored unless otherwise requested, preventing users from seeing warnings triggered by an application.

• Previous Python 2.x releases had DeprecationWarning ON by default. Now, since the path to upgrade is 3.x, those have been silenced unless explictly requested.

• You can re-enable display of DeprecationWarning messages by running Python with the -Wdefault (short form: -Wd) switch, or by setting the PYTHONWARNINGS environment variable to "default" (or "d") before running Python.

• 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 with statement.

• A new version of the io library, rewritten in C for performance.

• The ordered-dictionary type described in PEP 372

• The new "," format specifier for Thousands Separator PEP 378

• The memoryview object and this is further improved in 3.3

• A small subset of the importlib module and full version of importlib will be in place in 3.3

• viewkeys(), viewvalues(), and viewitems() return an object called views.

http://stackoverflow.com/questions/340850/python-3-0-dict-methods-return-views-why

• http://docs.python.org/whatsnew/2.7.html#new-and-improved-modules

• 2.7.x is the maintained bug fix release. All bug reports which have been reported have found it's way to 2.7.x

• Only new features do not make it to 2.7.

• It's a stable release which can you to upgrade to Python 3.x

• http://docs.python.org/dev/whatsnew/3.3.html

• http://docs.python.org/dev/whatsnew/3.2.html

• http://docs.python.org/dev/whatsnew/2.7.html

• Misc/NEWS file.

print('{0} {1}'.format('Thank',' you!'))

• Presentation - http://bit.ly/pycon2012stdlib