mirror of https://github.com/python/cpython
More updates to whatsnew3.2
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Raymond Hettinger
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@ -53,22 +53,18 @@ This article explains the new features in Python 3.2, compared to 3.1.
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PEP 391: Dictionary Based Configuration for Logging
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====================================================
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The :mod:`logging` module had two ways of configuring the module, either by calling
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functions for each option or by reading an external file saved in a :mod:`ConfigParser`
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format. Those options did not provide the flexibility to create configurations
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from JSON or YAML files and they did not support incremental configuration, which
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is needed for specifying logger options from a command line.
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The :mod:`logging` module provided two kinds of configuration, one style with
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function calls for each option or another style driven by an external file saved
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in a :mod:`ConfigParser` format. Those options did not provide the flexibility
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to create configurations from JSON or YAML files, nor they did not support
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incremental configuration, which is needed for specifying logger options from a
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command line.
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To support a more flexible style, the module now offers
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:func:`logging.config.dictConfig` to use dictionaries to specify logger
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configuration (including formatters, handlers, filters, and loggers). For
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example:
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>>> import logging.config
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>>> logging.config.dictConfig(json.load(open('log.cfg', 'rb')))
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The above fragment configures logging from a JSON-encoded dictionary stored in a
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file called "log.cfg". Here's a working example of a configuration dictionary::
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:func:`logging.config.dictConfig` for specifying logging configuration with
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plain Python dictionaries. The configuration options include formatters,
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handlers, filters, and loggers. Here's a working example of a configuration
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dictionary::
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{"version": 1,
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"formatters": {"brief": {"format": "%(levelname)-8s: %(name)-15s: %(message)s"},
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@ -87,6 +83,15 @@ file called "log.cfg". Here's a working example of a configuration dictionary::
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},
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"root": {"level": "DEBUG", "handlers": ["console", "console_priority"]}}
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If that dictionary is stored in a file called "conf.json", it can loaded
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and called with code like this::
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>>> import logging.config
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>>> logging.config.dictConfig(json.load(open('conf.json', 'rb')))
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>>> logging.info("Transaction completed normally")
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>>> logging.critical("Abnormal termination")
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.. seealso::
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:pep:`391` - Dictionary Based Configuration for Logging
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@ -119,16 +124,16 @@ aspects that are visible to the programmer:
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* Imported modules now have a :attr:`__cached__` attribute which stores the name
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of the actual file that was imported:
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>>> import collections
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>>> collections.__cached__
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'c:/py32/lib/__pycache__/collections.cpython-32.pyc'
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>>> import collections
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>>> collections.__cached__
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'c:/py32/lib/__pycache__/collections.cpython-32.pyc'
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* The tag that is unique to each interpreter is accessible from the :mod:`imp`
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module:
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>>> import imp
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>>> imp.get_tag()
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'cpython-32'
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>>> import imp
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>>> imp.get_tag()
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'cpython-32'
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* Scripts that try to deduce source filename from the imported file now need to
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be smarter. It is no longer sufficient to simply strip the "c" from a ".pyc"
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@ -199,10 +204,10 @@ Some smaller changes made to the core Python language are:
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caused confusion and is no longer needed now that the shortest possible
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:func:`repr` is displayed by default:
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>>> repr(math.pi)
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'3.141592653589793'
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>>> str(math.pi)
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'3.141592653589793'
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>>> repr(math.pi)
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'3.141592653589793'
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>>> str(math.pi)
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'3.141592653589793'
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(Proposed and implemented by Mark Dickinson; :issue:`9337`.)
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@ -218,8 +223,22 @@ Some smaller changes made to the core Python language are:
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* The :mod:`abc` module now supports :func:`~abc.abstractclassmethod` and
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:func:`~abc.abstractstaticmethod`.
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(:issue:`5867`.)
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(Patch submitted by Daniel Urban; :issue:`5867`.)
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* A warning message will now get printed at interpreter shutdown if the
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:data:`gc.garbage` list isn't empty. This is meant to make the programmer
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aware that their code contains object finalization issues.
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(Added by Antoine Pitrou; :issue:`477863`.)
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* Mark Dickinson crafted an elegant and efficient scheme for assuring that
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different numeric datatypes will have the same hash value whenever their
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actual values are equal::
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>>> assert hash(Fraction(3, 2)) == hash(1.5) == \
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hash(Decimal("1.5")) == hash(complex(1.5, 0))
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(See :issue:`8188`.)
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New, Improved, and Deprecated Modules
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=====================================
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@ -263,26 +282,28 @@ New, Improved, and Deprecated Modules
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* The :class:`ftplib.FTP` class now supports the context manager protocol to
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unconditionally consume :exc:`socket.error` exceptions and to close the FTP
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connection when done:
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connection when done::
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>>> from ftplib import FTP
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>>> with FTP("ftp1.at.proftpd.org") as ftp:
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... ftp.login()
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... ftp.dir()
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...
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'230 Anonymous login ok, restrictions apply.'
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dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .
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dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 ..
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dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS
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dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora
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>>> from ftplib import FTP
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>>> with FTP("ftp1.at.proftpd.org") as ftp:
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... ftp.login()
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... ftp.dir()
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...
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'230 Anonymous login ok, restrictions apply.'
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dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .
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dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 ..
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dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS
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dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora
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(Contributed by Tarek Ziadé and Giampaolo Rodolà; :issue:`4972`.)
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Other file-like objects such as :class:`mmap.mmap` and :func:`fileinput.input`
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also grew auto-closing context managers::
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* A warning message will now get printed at interpreter shutdown if the
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:data:`gc.garbage` list isn't empty. This is meant to make the programmer
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aware that their code contains object finalization issues.
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with fileinput.input(files=('log1.txt', 'log2.txt')) as f:
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for line in f:
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process(line)
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(Added by Antoine Pitrou; :issue:`477863`.)
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(Contributed by Tarek Ziadé and Giampaolo Rodolà in :issue:`4972`, and
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by Georg Brandl in :issue:`8046` and :issue:`1286`.)
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* The :mod:`os` module now has the :const:`ST_RDONLY` and :const:`ST_NOSUID`
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constants, for use with the :func:`~os.statvfs` function.
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@ -395,15 +416,39 @@ Multi-threading
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argument. (Contributed by Torsten Landschoff; :issue:`850728`.)
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.. Optimizations
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=============
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Optimizations
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=============
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Major performance enhancements have been added:
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A number of small performance enhancements have been added:
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* Stub
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* JSON decoding performance is improved and memory consumption is reduced
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whenever the same string is repeated for multiple keys.
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(Contributed by Antoine Pitrou; :issue:`7451`.)
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Filenames and unicode
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- Python's peephole optimizer now recognizes patterns such ``x in {1, 2, 3}`` as
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being a test for membership in a set of constants. The optimizer recasts the
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:class:`set` as a :class:`frozenset` and stores the pre-built constant.
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Now that the speed penalty is gone, it is practical to start writing
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membership tests using set-notation. This style is both semantically clear
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and operationally fast::
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extension = name.rpartition('.')[2]
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if extension in {'xml', 'html', 'xhtml', 'css'}:
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handle(name)
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(Patch and additional tests by Dave Malcolm; :issue:`6690`).
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* The fast-search algorithm in stringlib is now used by the :meth:`split`,
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:meth:`rsplit`, :meth:`splitlines` and :meth:`replace` methods on
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:class:`bytes`, :class:`bytearray` and :class:`str` objects. Likewise, the
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algorithm is also used by :meth:`rfind`, :meth:`rindex`, :meth:`rsplit` and
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:meth:`rpartition`.
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(Patch by Florent Xicluna in :issue:`7622` and :issue:`7462`.)
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Filenames and Unicode
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=====================
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The filesystem encoding can be specified by setting the
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