[Python-checkins] r61222 - python/trunk/Doc/whatsnew/2.6.rst
andrew.kuchling
python-checkins at python.org
Tue Mar 4 02:50:33 CET 2008
Author: andrew.kuchling
Date: Tue Mar 4 02:50:32 2008
New Revision: 61222
Modified:
python/trunk/Doc/whatsnew/2.6.rst
Log:
Thesis night results: add various items
Modified: python/trunk/Doc/whatsnew/2.6.rst
==============================================================================
--- python/trunk/Doc/whatsnew/2.6.rst (original)
+++ python/trunk/Doc/whatsnew/2.6.rst Tue Mar 4 02:50:32 2008
@@ -450,6 +450,15 @@
.. ======================================================================
+.. _pep-3101:
+
+PEP 3101: Advanced String Formatting
+=====================================================
+
+XXX write this
+
+.. ======================================================================
+
.. _pep-3110:
PEP 3110: Exception-Handling Changes
@@ -544,6 +553,32 @@
.. ======================================================================
+.. _pep-3127:
+
+PEP 3127: Integer Literal Support and Syntax
+=====================================================
+
+XXX write this
+
+Python 3.0 changes the syntax for octal integer literals, and
+adds supports for binary integers: 0o instad of 0,
+and 0b for binary. Python 2.6 doesn't support this, but a bin()
+builtin was added, and
+
+
+New bin() built-in returns the binary form of a number.
+
+.. ======================================================================
+
+.. _pep-3129:
+
+PEP 3129: Class Decorators
+=====================================================
+
+XXX write this.
+
+.. ======================================================================
+
.. _pep-3141:
PEP 3141: A Type Hierarchy for Numbers
@@ -579,7 +614,9 @@
:class:`Rational` numbers derive from :class:`Real`, have
:attr:`numerator` and :attr:`denominator` properties, and can be
converted to floats. Python 2.6 adds a simple rational-number class,
-:class:`Fraction`, in the :mod:`fractions` module.
+:class:`Fraction`, in the :mod:`fractions` module. (It's called
+:class:`Fraction` instead of :class:`Rational` to avoid
+a name clash with :class:`numbers.Rational`.)
:class:`Integral` numbers derive from :class:`Rational`, and
can be shifted left and right with ``<<`` and ``>>``,
@@ -587,9 +624,9 @@
and can be used as array indexes and slice boundaries.
In Python 3.0, the PEP slightly redefines the existing built-ins
-:func:`math.floor`, :func:`math.ceil`, :func:`round`, and adds a new
-one, :func:`trunc`, that's been backported to Python 2.6.
-:func:`trunc` rounds toward zero, returning the closest
+:func:`round`, :func:`math.floor`, :func:`math.ceil`, and adds a new
+one, :func:`math.trunc`, that's been backported to Python 2.6.
+:func:`math.trunc` rounds toward zero, returning the closest
:class:`Integral` that's between the function's argument and zero.
.. seealso::
@@ -603,7 +640,7 @@
To fill out the hierarchy of numeric types, a rational-number class
has been added as the :mod:`fractions` module. Rational numbers are
-represented as a fraction; rational numbers can exactly represent
+represented as a fraction, and can exactly represent
numbers such as two-thirds that floating-point numbers can only
approximate.
@@ -692,7 +729,7 @@
A numerical nicety: when creating a complex number from two floats
on systems that support signed zeros (-0 and +0), the
- :func:`complex()` constructor will now preserve the sign
+ :func:`complex` constructor will now preserve the sign
of the zero.
.. Patch 1507
@@ -789,6 +826,15 @@
built-in types. This speeds up checking if an object is a subclass of one of
these types. (Contributed by Neal Norwitz.)
+* Unicode strings now uses faster code for detecting
+ whitespace and line breaks; this speeds up the :meth:`split` method
+ by about 25% and :meth:`splitlines` by 35%.
+ (Contributed by Antoine Pitrou.)
+
+* To reduce memory usage, the garbage collector will now clear internal
+ free lists when garbage-collecting the highest generation of objects.
+ This may return memory to the OS sooner.
+
The net result of the 2.6 optimizations is that Python 2.6 runs the pystone
benchmark around XX% faster than Python 2.5.
@@ -956,15 +1002,69 @@
can also be accessed as attributes.
(Contributed by Raymond Hettinger.)
-* A new function in the :mod:`itertools` module: ``izip_longest(iter1, iter2,
- ...[, fillvalue])`` makes tuples from each of the elements; if some of the
- iterables are shorter than others, the missing values are set to *fillvalue*.
- For example::
+ Some new functions in the module include
+ :func:`isgenerator`, :func:`isgeneratorfunction`,
+ and :func:`isabstract`.
+
+* The :mod:`itertools` module gained several new functions.
+
+ ``izip_longest(iter1, iter2, ...[, fillvalue])`` makes tuples from
+ each of the elements; if some of the iterables are shorter than
+ others, the missing values are set to *fillvalue*. For example::
itertools.izip_longest([1,2,3], [1,2,3,4,5]) ->
[(1, 1), (2, 2), (3, 3), (None, 4), (None, 5)]
- (Contributed by Raymond Hettinger.)
+ ``product(iter1, iter2, ..., [repeat=N])`` returns the Cartesian product
+ of the supplied iterables, a set of tuples containing
+ every possible combination of the elements returned from each iterable. ::
+
+ itertools.product([1,2,3], [4,5,6]) ->
+ [(1, 4), (1, 5), (1, 6),
+ (2, 4), (2, 5), (2, 6),
+ (3, 4), (3, 5), (3, 6)]
+
+ The optional *repeat* keyword argument is used for taking the
+ product of an iterable or a set of iterables with themselves,
+ repeated *N* times. With a single iterable argument, *N*-tuples
+ are returned::
+
+ itertools.product([1,2], repeat=3)) ->
+ [(1, 1, 1), (1, 1, 2), (1, 2, 1), (1, 2, 2),
+ (2, 1, 1), (2, 1, 2), (2, 2, 1), (2, 2, 2)]
+
+ With two iterables, *2N*-tuples are returned. ::
+
+ itertools(product([1,2], [3,4], repeat=2) ->
+ [(1, 3, 1, 3), (1, 3, 1, 4), (1, 3, 2, 3), (1, 3, 2, 4),
+ (1, 4, 1, 3), (1, 4, 1, 4), (1, 4, 2, 3), (1, 4, 2, 4),
+ (2, 3, 1, 3), (2, 3, 1, 4), (2, 3, 2, 3), (2, 3, 2, 4),
+ (2, 4, 1, 3), (2, 4, 1, 4), (2, 4, 2, 3), (2, 4, 2, 4)]
+
+ ``combinations(iter, r)`` returns combinations of length *r* from
+ the elements of *iterable*. ::
+
+ itertools.combinations('123', 2) ->
+ [('1', '2'), ('1', '3'), ('2', '3')]
+
+ itertools.combinations('123', 3) ->
+ [('1', '2', '3')]
+
+ itertools.combinations('1234', 3) ->
+ [('1', '2', '3'), ('1', '2', '4'), ('1', '3', '4'),
+ ('2', '3', '4')]
+
+ ``itertools.chain(*iterables)` is an existing function in
+ :mod:`itertools` that gained a new constructor.
+ ``itertools.chain.from_iterable(iterable)`` takes a single
+ iterable that should return other iterables. :func:`chain` will
+ then return all the elements of the first iterable, then
+ all the elements of the second, and so on. ::
+
+ chain.from_iterable([[1,2,3], [4,5,6]]) ->
+ [1, 2, 3, 4, 5, 6]
+
+ (All contributed by Raymond Hettinger.)
* The :mod:`macfs` module has been removed. This in turn required the
:func:`macostools.touched` function to be removed because it depended on the
@@ -975,7 +1075,7 @@
* :class:`mmap` objects now have a :meth:`rfind` method that finds
a substring, beginning at the end of the string and searching
backwards. The :meth:`find` method
- also gained a *end* parameter containing the index at which to stop
+ also gained an *end* parameter containing the index at which to stop
the forward search.
(Contributed by John Lenton.)
@@ -984,6 +1084,29 @@
triggers a warning message when Python is running in 3.0-warning
mode.
+* The :mod:`operator` module gained a
+ :func:`methodcaller` function that takes a name and an optional
+ set of arguments, returning a callable that will call
+ the named function on any arguments passed to it. For example::
+
+ >>> # Equivalent to lambda s: s.replace('old', 'new')
+ >>> replacer = operator.methodcaller('replace', 'old', 'new')
+ >>> replacer('old wine in old bottles')
+ 'new wine in new bottles'
+
+ (Contributed by Gregory Petrosyan.)
+
+ The :func:`attrgetter` function now accepts dotted names and performs
+ the corresponding attribute lookups::
+
+ >>> inst_name = operator.attrgetter('__class__.__name__')
+ >>> inst_name('')
+ 'str'
+ >>> inst_name(help)
+ '_Helper'
+
+ (Contributed by Scott Dial, after a suggestion by Barry Warsaw.)
+
* New functions in the :mod:`os` module include
``fchmod(fd, mode)``, ``fchown(fd, uid, gid)``,
and ``lchmod(path, mode)``, on operating systems that support these
@@ -1036,6 +1159,11 @@
.. Patch #1393667
+* The :mod:`pickletools` module now has an :func:`optimize` function
+ that takes a string containing a pickle and removes some unused
+ opcodes, returning a shorter pickle that contains the same data structure.
+ (Contributed by Raymond Hettinger.)
+
* New functions in the :mod:`posix` module: :func:`chflags` and :func:`lchflags`
are wrappers for the corresponding system calls (where they're available).
Constants for the flag values are defined in the :mod:`stat` module; some
@@ -1099,6 +1227,10 @@
.. % Patch 1583
+ The :func:`siginterrupt` function is now available from Python code,
+ and allows changing whether signals can interrupt system calls or not.
+ (Contributed by Ralf Schmitt.)
+
* The :mod:`smtplib` module now supports SMTP over SSL thanks to the
addition of the :class:`SMTP_SSL` class. This class supports an
interface identical to the existing :class:`SMTP` class. Both
@@ -1201,6 +1333,18 @@
.. Patch #1537850
+ A new class, :class:`SpooledTemporaryFile`, behaves like
+ a temporary file but stores its data in memory until a maximum size is
+ exceeded. On reaching that limit, the contents will be written to
+ an on-disk temporary file. (Contributed by Dustin J. Mitchell.)
+
+ The :class:`NamedTemporaryFile` and :class:`SpooledTemporaryFile` classes
+ both work as context managers, so you can write
+ ``with tempfile.NamedTemporaryFile() as tmp: ...``.
+ (Contributed by Alexander Belopolsky.)
+
+ .. Issue #2021
+
* The :mod:`test.test_support` module now contains a
:func:`EnvironmentVarGuard`
context manager that supports temporarily changing environment variables and
@@ -1415,6 +1559,12 @@
.. Patch 1530959
+* Several basic data types, such as integers and strings, maintain
+ internal free lists of objects that can be re-used. The data
+ structures for these free lists now follow a naming convention: the
+ variable is always named ``free_list``, the counter is always named
+ ``numfree``, and a macro :cmacro:`Py<typename>_MAXFREELIST` is
+ always defined.
.. ======================================================================
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