cpython/Doc/whatsnew/2.7.rst

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****************************
What's New in Python 2.7
****************************
:Author: A.M. Kuchling (amk at amk.ca)
:Release: |release|
:Date: |today|
.. $Id$
Rules for maintenance:
* Anyone can add text to this document. Do not spend very much time
on the wording of your changes, because your text will probably
get rewritten to some degree.
* The maintainer will go through Misc/NEWS periodically and add
changes; it's therefore more important to add your changes to
Misc/NEWS than to this file.
* This is not a complete list of every single change; completeness
is the purpose of Misc/NEWS. Some changes I consider too small
or esoteric to include. If such a change is added to the text,
I'll just remove it. (This is another reason you shouldn't spend
too much time on writing your addition.)
* If you want to draw your new text to the attention of the
maintainer, add 'XXX' to the beginning of the paragraph or
section.
* It's OK to just add a fragmentary note about a change. For
example: "XXX Describe the transmogrify() function added to the
socket module." The maintainer will research the change and
write the necessary text.
* You can comment out your additions if you like, but it's not
necessary (especially when a final release is some months away).
* Credit the author of a patch or bugfix. Just the name is
sufficient; the e-mail address isn't necessary.
* It's helpful to add the bug/patch number in a parenthetical comment.
XXX Describe the transmogrify() function added to the socket
module.
(Contributed by P.Y. Developer; :issue:`12345`.)
This saves the maintainer some effort going through the SVN logs
when researching a change.
This article explains the new features in Python 2.7.
No release schedule has been decided yet for 2.7.
.. Compare with previous release in 2 - 3 sentences here.
add hyperlink when the documentation becomes available online.
.. ========================================================================
.. Large, PEP-level features and changes should be described here.
.. Should there be a new section here for 3k migration?
.. Or perhaps a more general section describing module changes/deprecation?
.. ========================================================================
Kristj<EFBFBD>n Valur J<>nsson, issue 4293
Py_AddPendingCall is now thread safe. This allows any worker thread
to submit notifications to the python main thread. This is particularly
useful for asynchronous IO operations.
Other Language Changes
======================
Some smaller changes made to the core Python language are:
* The :func:`int` and :func:`long` types gained a ``bit_length``
method that returns the number of bits necessary to represent
its argument in binary::
>>> n = 37
>>> bin(37)
'0b100101'
>>> n.bit_length()
6
>>> n = 2**123-1
>>> n.bit_length()
123
>>> (n+1).bit_length()
124
(Contributed by Fredrik Johansson and Victor Stinner; :issue:`3439`.)
.. ======================================================================
Optimizations
-------------
To be written.
.. ======================================================================
New, Improved, and Deprecated Modules
=====================================
As in every release, Python's standard library received a number of
enhancements and bug fixes. Here's a partial list of the most notable
changes, sorted alphabetically by module name. Consult the
:file:`Misc/NEWS` file in the source tree for a more complete list of
changes, or look through the Subversion logs for all the details.
* A new function in the :mod:`subprocess` module,
:func:`check_output`, runs a command with a specified set of arguments
and returns the command's output as a string if the command runs without
error, or raises a :exc:`CalledProcessError` exception otherwise.
::
>>> subprocess.check_output(['df', '-h', '.'])
'Filesystem Size Used Avail Capacity Mounted on\n
/dev/disk0s2 52G 49G 3.0G 94% /\n'
>>> subprocess.check_output(['df', '-h', '/bogus'])
...
subprocess.CalledProcessError: Command '['df', '-h', '/bogus']' returned non-zero exit status 1
(Contributed by Gregory P. Smith.)
* It is not mandatory anymore to store clear text passwords in the
:file:`.pypirc` file when registering and uploading packages to PyPI. As long
as the username is present in that file, the :mod:`distutils` package will
prompt for the password if not present. (Added by tarek, with the initial
contribution of Nathan Van Gheem; :issue:`4394`.)
.. ======================================================================
.. whole new modules get described in subsections here
.. ======================================================================
Build and C API Changes
=======================
Changes to Python's build process and to the C API include:
* If you use the :file:`.gdbinit` file provided with Python,
the "pyo" macro in the 2.7 version will now work when the thread being
debugged doesn't hold the GIL; the macro will now acquire it before printing.
(Contributed by haypo XXX; :issue:`3632`.)
.. ======================================================================
Port-Specific Changes: Windows
-----------------------------------
* The :mod:`msvcrt` module now contains some constants from
the :file:`crtassem.h` header file:
:data:`CRT_ASSEMBLY_VERSION`,
:data:`VC_ASSEMBLY_PUBLICKEYTOKEN`,
and :data:`LIBRARIES_ASSEMBLY_NAME_PREFIX`.
(Added by Martin von Loewis (XXX check); :issue:`4365`.)
.. ======================================================================
Port-Specific Changes: Mac OS X
-----------------------------------
.. ======================================================================
Porting to Python 2.7
=====================
This section lists previously described changes and other bugfixes
that may require changes to your code:
To be written.
.. ======================================================================
.. _acks27:
Acknowledgements
================
The author would like to thank the following people for offering
suggestions, corrections and assistance with various drafts of this
article: no one yet.