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Add various items
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Andrew M. Kuchling
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@ -88,8 +88,25 @@ Other Language Changes
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Some smaller changes made to the core Python language are:
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* The string :method:`format` method now supports automatic numbering
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of the replacement fields. This makes using :meth:`format`
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more closely resemble using ``%s`` formatting::
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>>> '{}:{}:{}'.format(2009, 04, 'Sunday')
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'2009:4:Sunday'
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>>> '{}:{}:{day}'.format(2009, 4, day='Sunday')
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'2009:4:Sunday'
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The auto-numbering takes the fields from left to right, so the first
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``{...}`` specifier will use the first argument to :meth:`format`,
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the next specifier will use the next argument, and so on. You can't
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mix auto-numbering and explicit numbering -- either number all of
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your specifier fields or none of them -- but you can mix
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auto-numbering and named fields, as in the second example above.
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(Contributed by XXX; :issue`5237`.)
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* The :func:`int` and :func:`long` types gained a ``bit_length``
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method that returns the number of bits necessary to represent
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'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' method that returns the number of bits necessary to represent
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its argument in binary::
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>>> n = 37
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@ -106,7 +123,7 @@ Some smaller changes made to the core Python language are:
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(Contributed by Fredrik Johansson and Victor Stinner; :issue:`3439`.)
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* The :class:`bytearray` type's :meth:`translate` method will
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now accept None as its first argument. (Fixed by Georg Brandl;
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now accept ``None`` as its first argument. (Fixed by Georg Brandl;
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:issue:`4759`.)
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.. ======================================================================
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@ -201,7 +218,7 @@ changes, or look through the Subversion logs for all the details.
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management protocol, so you can write ``with bz2.BZ2File(...) as f: ...``.
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(Contributed by Hagen Fuerstenau; :issue:`3860`.)
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* A new :class:`Counter` class in the :mod:`collections` module is
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* New class: the :class:`Counter` class in the :mod:`collections` module is
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useful for tallying data. :class:`Counter` instances behave mostly
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like dictionaries but return zero for missing keys instead of
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raising a :exc:`KeyError`::
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@ -236,7 +253,7 @@ changes, or look through the Subversion logs for all the details.
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Contributed by Raymond Hettinger; :issue:`1696199`.
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The :class:`namedtuple` class now has an optional *rename* parameter.
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If *rename* is True, field names that are invalid because they've
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If *rename* is true, field names that are invalid because they've
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been repeated or that aren't legal Python identifiers will be
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renamed to legal names that are derived from the field's
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position within the list of fields:
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@ -247,8 +264,13 @@ changes, or look through the Subversion logs for all the details.
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(Added by Raymond Hettinger; :issue:`1818`.)
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The :class:`deque` data type now exposes its maximum length as the
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read-only :attr:`maxlen` attribute. (Added by Raymond Hettinger.)
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* In Distutils, :func:`distutils.sdist.add_defaults` now uses
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*package_dir* and *data_files* to create the MANIFEST file.
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:mod:`distutils.sysconfig` will now read the :envvar:`AR`
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environment variable.
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It is no longer mandatory to store clear-text passwords in the
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:file:`.pypirc` file when registering and uploading packages to PyPI. As long
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@ -256,6 +278,12 @@ changes, or look through the Subversion logs for all the details.
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prompt for the password if not present. (Added by Tarek Ziade,
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based on an initial contribution by Nathan Van Gheem; :issue:`4394`.)
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A Distutils setup can now specify that a C extension is optional by
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setting the *optional* option setting to true. If this optional is
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supplied, failure to build the extension will not abort the build
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process, but instead simply not install the failing extension.
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(Contributed by XXX; :issue:`5583`.)
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* New method: the :class:`Decimal` class gained a
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:meth:`from_float` class method that performs an exact conversion
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of a floating-point number to a :class:`Decimal`.
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@ -267,8 +295,8 @@ changes, or look through the Subversion logs for all the details.
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``Decimal('0.1000000000000000055511151231257827021181583404541015625')``.
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(Implemented by Raymond Hettinger; :issue:`4796`.)
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* A new function in the :mod:`gc` module, :func:`is_tracked`, returns
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True if a given instance is tracked by the garbage collector, False
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* New function: the :mod:`gc` module's :func:`is_tracked` returns
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true if a given instance is tracked by the garbage collector, false
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otherwise. (Contributed by Antoine Pitrou; :issue:`4688`.)
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* The :mod:`gzip` module's :class:`GzipFile` now supports the context
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@ -284,7 +312,7 @@ changes, or look through the Subversion logs for all the details.
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* New function: ``itertools.compress(*data*, *selectors*)`` takes two
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iterators. Elements of *data* are returned if the corresponding
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value in *selectors* is True::
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value in *selectors* is true::
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itertools.compress('ABCDEF', [1,0,1,0,1,1]) =>
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A, C, E, F
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@ -332,8 +360,12 @@ changes, or look through the Subversion logs for all the details.
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uses. You can now do ``help('<<')`` or ``help('@')``, for example.
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(Contributed by David Laban; :issue:`4739`.)
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* A new function in the :mod:`subprocess` module,
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:func:`check_output`, runs a command with a specified set of arguments
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* The :mod:`re` module's :func:`split`, :func:`sub`, and :func:`subn`
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now accept an optional *flags* argument, for consistency with the
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other functions in the module. (Added by Gregory P. Smith.)
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* New function: the :mod:`subprocess` module's
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:func:`check_output` runs a command with a specified set of arguments
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and returns the command's output as a string when the command runs without
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error, or raises a :exc:`CalledProcessError` exception otherwise.
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@ -349,13 +381,25 @@ changes, or look through the Subversion logs for all the details.
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(Contributed by Gregory P. Smith.)
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* New function: :func:`is_declared_global` in the :mod:`symtable` module
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returns true for variables that are explicitly declared to be global,
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false for ones that are implicitly global.
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(Contributed by Jeremy Hylton.)
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* The ``sys.version_info`` value is now a named tuple, with attributes
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named ``major``, ``minor``, ``micro``, ``releaselevel``, and ``serial``.
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(Contributed by Ross Light; :issue:`4285`.)
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* The :mod:`threading` module's :meth:`Event.wait` method now returns
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the internal flag on exit. This means the method will usually
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return true because :meth:`wait` is supposed to block until the
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internal flag becomes true. The return value will only be false if
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a timeout was provided and the operation timed out.
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(Contributed by XXX; :issue:`1674032`.)
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* The :mod:`unittest` module was enhanced in several ways.
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The progress messages will now print 'x' for expected failures
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and 'u' for unexpected successes when run in its verbose mode.
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The progress messages will now show 'x' for expected failures
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and 'u' for unexpected successes when run in verbose mode.
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(Contributed by Benjamin Peterson.)
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Test cases can raise the :exc:`SkipTest` exception to skip a test.
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(:issue:`1034053`.)
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@ -443,7 +487,37 @@ changes, or look through the Subversion logs for all the details.
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importlib: Importing Modules
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------------------------------
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XXX write this
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Python 3.1 includes the :mod:`importlib` package, a re-implementation
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of the logic underlying Python's :keyword:`import` statement.
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:mod:`importlib` is useful for implementors of Python interpreters and
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to user who wish to write new importers that can participate in the
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import process. Python 2.7 doesn't contain the complete
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:mod:`importlib` package, but instead has a tiny subset that contains
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a single function, :func:`import_module`.
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``import_module(*name*, *package*=None)`` imports a module. *name* is
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a string containing the module or package's name. It's possible to do
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relative imports by providing a string that begins with a ``.``
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character, such as ``..utils.errors``. For relative imports, the
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*package* argument must be provided and is the name of the package that
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will be used as the anchor for
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the relative import. :func:`import_module` both inserts the imported
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module into ``sys.modules`` and returns the module object.
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Here are some examples::
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>>> from importlib import import_module
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>>> anydbm = import_module('anydbm') # Standard absolute import
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>>> anydbm
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<module 'anydbm' from '/p/python/Lib/anydbm.py'>
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>>> # Relative import
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>>> sysconfig = import_module('..sysconfig', 'distutils.command')
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>>> sysconfig
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<module 'distutils.sysconfig' from '/p/python/Lib/distutils/sysconfig.pyc'>
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:mod:`importlib` was implemented by Brett Cannon and introduced in
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Python 3.1.
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ttk: Themed Widgets for Tk
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--------------------------
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