[Python-checkins] r80870 - python/trunk/Doc/whatsnew/2.7.rst
andrew.kuchling
python-checkins at python.org
Thu May 6 16:14:09 CEST 2010
Author: andrew.kuchling
Date: Thu May 6 16:14:09 2010
New Revision: 80870
Log:
Describe ElementTree 1.3; rearrange new-module sections; describe dict views as sets; small edits and items
Modified:
python/trunk/Doc/whatsnew/2.7.rst
Modified: python/trunk/Doc/whatsnew/2.7.rst
==============================================================================
--- python/trunk/Doc/whatsnew/2.7.rst (original)
+++ python/trunk/Doc/whatsnew/2.7.rst Thu May 6 16:14:09 2010
@@ -8,10 +8,11 @@
.. Fix accents on Kristjan Valur Jonsson, Fuerstenau
-.. Big jobs: ElementTree 1.3, pep 391
+.. Big jobs: pep 391
.. hyperlink all the methods & functions.
.. T_STRING_INPLACE not described in main docs
+.. XXX "Format String Syntax" in string.rst could use many more examples.
.. $Id$
Rules for maintenance:
@@ -238,8 +239,6 @@
comma-formatting mechanism isn't as general as the :mod:`locale`
module, but it's easier to use.
-.. XXX "Format String Syntax" in string.rst could use many more examples.
-
.. seealso::
:pep:`378` - Format Specifier for Thousands Separator
@@ -366,7 +365,7 @@
.. rev79293
-* :class:`Logger` instances gained a :meth:`getChild` that retrieves a
+* :class:`Logger` instances gained a :meth:`getChild` method that retrieves a
descendant logger using a relative path. For example,
once you retrieve a logger by doing ``log = getLogger('app')``,
calling ``log.getChild('network.listen')`` is equivalent to
@@ -388,8 +387,6 @@
are different in Python 3.x. They return an object called a :dfn:`view`
instead of a fully materialized list.
-.. Views can be iterated over, but they also behave like sets. XXX not working.
-
It's not possible to change the return values of :meth:`keys`,
:meth:`values`, and :meth:`items` in Python 2.7 because too much code
would break. Instead the 3.x versions were added under the new names
@@ -403,6 +400,16 @@
>>> d.viewkeys()
dict_keys([0, 130, 10, 140, 20, 150, 30, ..., 250])
+Views can be iterated over, but they also behave like sets. The ``&``
+operator performs intersection, and ``|`` performs a union::
+
+ >>> d1 = dict((i*10, chr(65+i)) for i in range(26))
+ >>> d2 = dict((i**.5, i) for i in range(1000))
+ >>> d1.viewkeys() & d2.viewkeys()
+ set([0.0, 10.0, 20.0, 30.0])
+ >>> d1.viewkeys() | range(0, 30)
+ set([0, 1, 130, 3, 4, 5, 6, ..., 120, 250])
+
The view keeps track of the dictionary and its contents change as the
dictionary is modified::
@@ -940,6 +947,11 @@
length as the read-only :attr:`~collections.deque.maxlen` attribute.
(Both features added by Raymond Hettinger.)
+* Deprecated function: :func:`contextlib.nested`, which allows
+ handling more than one context manager with a single :keyword:`with`
+ statement, has been deprecated, because :keyword:`with` supports
+ multiple context managers syntactically now.
+
* The :mod:`copy` module's :func:`~copy.deepcopy` function will now
correctly copy bound instance methods. (Implemented by
Robert Collins; :issue:`1515`.)
@@ -1437,9 +1449,9 @@
management protocol, so you can write ``with zipfile.ZipFile(...) as f: ...``.
(Contributed by Brian Curtin; :issue:`5511`.)
- :mod:`zipfile` now supports archiving empty directories and
+ :mod:`zipfile` now also supports archiving empty directories and
extracts them correctly. (Fixed by Kuba Wieczorek; :issue:`4710`.)
- Reading files out of an archive is now faster, and interleaving
+ Reading files out of an archive is faster, and interleaving
:meth:`~zipfile.ZipFile.read` and :meth:`~zipfile.ZipFile.readline` now works correctly.
(Contributed by Nir Aides; :issue:`7610`.)
@@ -1453,6 +1465,47 @@
:issue:`6003`.)
+.. ======================================================================
+.. whole new modules get described in subsections here
+
+
+.. _importlib-section:
+
+New module: importlib
+------------------------------
+
+Python 3.1 includes the :mod:`importlib` package, a re-implementation
+of the logic underlying Python's :keyword:`import` statement.
+:mod:`importlib` is useful for implementors of Python interpreters and
+to users who wish to write new importers that can participate in the
+import process. Python 2.7 doesn't contain the complete
+:mod:`importlib` package, but instead has a tiny subset that contains
+a single function, :func:`~importlib.import_module`.
+
+``import_module(name, package=None)`` imports a module. *name* is
+a string containing the module or package's name. It's possible to do
+relative imports by providing a string that begins with a ``.``
+character, such as ``..utils.errors``. For relative imports, the
+*package* argument must be provided and is the name of the package that
+will be used as the anchor for
+the relative import. :func:`~importlib.import_module` both inserts the imported
+module into ``sys.modules`` and returns the module object.
+
+Here are some examples::
+
+ >>> from importlib import import_module
+ >>> anydbm = import_module('anydbm') # Standard absolute import
+ >>> anydbm
+ <module 'anydbm' from '/p/python/Lib/anydbm.py'>
+ >>> # Relative import
+ >>> sysconfig = import_module('..sysconfig', 'distutils.command')
+ >>> sysconfig
+ <module 'distutils.sysconfig' from '/p/python/Lib/distutils/sysconfig.pyc'>
+
+:mod:`importlib` was implemented by Brett Cannon and introduced in
+Python 3.1.
+
+
New module: sysconfig
---------------------------------
@@ -1482,15 +1535,26 @@
renamed by Tarek Ziadé.
-Updated module: ElementTree 1.3
----------------------------------
+ttk: Themed Widgets for Tk
+--------------------------
-XXX write this.
+Tcl/Tk 8.5 includes a set of themed widgets that re-implement basic Tk
+widgets but have a more customizable appearance and can therefore more
+closely resemble the native platform's widgets. This widget
+set was originally called Tile, but was renamed to Ttk (for "themed Tk")
+on being added to Tcl/Tck release 8.5.
-.. ======================================================================
-.. whole new modules get described in subsections here
+XXX write a brief discussion and an example here.
+
+The :mod:`ttk` module was written by Guilherme Polo and added in
+:issue:`2983`. An alternate version called ``Tile.py``, written by
+Martin Franklin and maintained by Kevin Walzer, was proposed for
+inclusion in :issue:`2618`, but the authors argued that Guilherme
+Polo's work was more comprehensive.
+.. _unittest-section:
+
Unit Testing Enhancements
---------------------------------
@@ -1668,67 +1732,91 @@
module is imported or used.
-.. _importlib-section:
-
-importlib: Importing Modules
-------------------------------
-
-Python 3.1 includes the :mod:`importlib` package, a re-implementation
-of the logic underlying Python's :keyword:`import` statement.
-:mod:`importlib` is useful for implementors of Python interpreters and
-to users who wish to write new importers that can participate in the
-import process. Python 2.7 doesn't contain the complete
-:mod:`importlib` package, but instead has a tiny subset that contains
-a single function, :func:`~importlib.import_module`.
-
-``import_module(name, package=None)`` imports a module. *name* is
-a string containing the module or package's name. It's possible to do
-relative imports by providing a string that begins with a ``.``
-character, such as ``..utils.errors``. For relative imports, the
-*package* argument must be provided and is the name of the package that
-will be used as the anchor for
-the relative import. :func:`~importlib.import_module` both inserts the imported
-module into ``sys.modules`` and returns the module object.
-
-Here are some examples::
-
- >>> from importlib import import_module
- >>> anydbm = import_module('anydbm') # Standard absolute import
- >>> anydbm
- <module 'anydbm' from '/p/python/Lib/anydbm.py'>
- >>> # Relative import
- >>> sysconfig = import_module('..sysconfig', 'distutils.command')
- >>> sysconfig
- <module 'distutils.sysconfig' from '/p/python/Lib/distutils/sysconfig.pyc'>
-
-:mod:`importlib` was implemented by Brett Cannon and introduced in
-Python 3.1.
-
-
-ttk: Themed Widgets for Tk
---------------------------
-
-Tcl/Tk 8.5 includes a set of themed widgets that re-implement basic Tk
-widgets but have a more customizable appearance and can therefore more
-closely resemble the native platform's widgets. This widget
-set was originally called Tile, but was renamed to Ttk (for "themed Tk")
-on being added to Tcl/Tck release 8.5.
-
-XXX write a brief discussion and an example here.
-
-The :mod:`ttk` module was written by Guilherme Polo and added in
-:issue:`2983`. An alternate version called ``Tile.py``, written by
-Martin Franklin and maintained by Kevin Walzer, was proposed for
-inclusion in :issue:`2618`, but the authors argued that Guilherme
-Polo's work was more comprehensive.
+.. _elementtree-section:
+Updated module: ElementTree 1.3
+---------------------------------
-Deprecations and Removals
-=========================
+The version of the ElementTree library included with Python was updated to
+version 1.3. Some of the new features in ElementTree 1.3 are:
-* :func:`contextlib.nested`, which allows handling more than one context manager
- with one :keyword:`with` statement, has been deprecated; :keyword:`with`
- supports multiple context managers syntactically now.
+* The various parsing functions now take a *parser* keyword argument
+ that can be used to provide an :class:`XMLParser` instance that will
+ be used. This makes it possible to override the file's internal encoding:
+
+ p = ET.XMLParser(encoding='utf-8')
+ t = ET.XML("""<root/>""", parser=p)
+
+ Errors in parsing XML now raise a :exc:`ParseError` exception.
+ Instances of :exc:`ParseError` have a :attr:`position` attribute
+ containing a (*line*, *column*) tuple giving the location of the problem.
+
+* ElementTree's code for converting trees to a string has been
+ significantly reworked, making it roughly twice as fast in many
+ cases. The :class:`ElementTree` :meth:`write` and :class:`Element`
+ :meth:`write` methods now have a *method* parameter that can be
+ "xml" (the default), "html", or "text". HTML mode will output empty
+ elements as ``<empty></empty>`` instead of ``<empty/>``, and text
+ mode will skip over elements and only output the text chunks. If
+ you set the :attr:`tag` attribute of an element to ``None`` but
+ leaves its children in place, the element will be omitted when the
+ tree is written out, so you don't need to do more extensive rearrangement
+ to remove a single element.
+
+ Namespace aspects have also been improved. All the ``xmlns:<whatever>``
+ declarations are now put on the root element and not scattered throughout
+ the resulting output. You can set the default namespace for a tree
+ by setting the :attr:`default_namespace` attribute and can
+ register new prefixes with :meth:`regsiter_namespace`. In XML mode,
+ you can use the true/false *xml_declaration* parameter to suppress the
+ XML declaration.
+
+* New :class:`Element` method: :meth:`extend` appends the items from a
+ sequence to the element's children. Elements themselves behave like
+ sequences, so it's easy to move children from one element to
+ another::
+
+ from xml.etree import ElementTree as ET
+
+ t = ET.XML("""<list>
+ <item>1</item> <item>2</item> <item>3</item>
+ </list>""")
+ new = ET.XML('<root/>')
+ new.extend(t)
+
+ # Outputs <root><item>1</item>...</root>
+ print ET.tostring(new)
+
+* New :class:`Element` method: :meth:`iter` yields the children of the
+ element as a generator. It's also possible to write ``for child in
+ elem: ...`` to loop over an element's children. The existing method
+ :meth:`getiterator` is now deprecated. :meth:`getchildren` is
+ another similar method that constructs and returns a list of
+ children; it's also deprecated.
+
+* New :class:`Element` method: :meth:`itertext` yields all chunks of
+ text that are descendants of the element. For example::
+
+ t = ET.XML("""<list>
+ <item>1</item> <item>2</item> <item>3</item>
+ </list>""")
+
+ # Outputs ['\n ', '1', ' ', '2', ' ', '3', '\n']
+ print list(t.itertext())
+
+* Deprecated: using an element as a Boolean (i.e., ``if elem: ...``)
+ would return true if the element had any children, or false if
+ there were no children. This behaviour will eventually change or be removed
+ because it's confusing (``None`` is false, but so is a childless element?),
+ so it will now trigger a :exc:`FutureWarning`. In your code,
+ you should be explicit: write ``len(elem) != 0`` if you're interested in
+ the number of children, or ``elem is not None`` Instead,
+
+Fredrik Lundh develops ElementTree and produced the 1.3 version;
+you can read his article describing 1.3 at
+http://effbot.org/zone/elementtree-13-intro.htm.
+Florent Xicluna updated the version included with
+Python, after discussions on python-dev and in :issue:`6472`.)
.. ======================================================================
@@ -1988,6 +2076,11 @@
This section lists previously described changes and other bugfixes
that may require changes to your code:
+* The :func:`range` function processes its arguments more
+ consistently; it will now call :meth:`__int__` on non-float,
+ non-integer arguments that are supplied to it. (Fixed by Alexander
+ Belopolsky; :issue:`1533`.)
+
* The string :meth:`format` method changed the default precision used
for floating-point and complex numbers from 6 decimal
places to 12, which matches the precision used by :func:`str`.
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