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Write summary of the 2.7 release; rewrite the future section some more; 

mention PYTHONWARNINGS env. var; tweak some examples for readability.

And with this commit, the "What's New" is done... except for a
complete read-through to polish the text, and fixing any reported errors,
but those tasks can easily wait until after beta2.
This commit is contained in:
Andrew M. Kuchling 2010-05-08 15:39:46 +00:00
parent dac6aeb43c
commit 0efe18ab0c
1 changed files with 39 additions and 15 deletions
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54
Doc/whatsnew/2.7.rst
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@ -6,12 +6,10 @@
:Release: |release|
:Date: |today|
.. Big jobs: pep 391 example
.. 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.
.. "Format String Syntax" in string.rst could use many more examples.
.. $Id$
Rules for maintenance:
@ -58,8 +56,27 @@ This article explains the new features in Python 2.7. The final
release of 2.7 is currently scheduled for July 2010; the detailed
schedule is described in :pep:`373`.
.. Compare with previous release in 2 - 3 sentences here.
add hyperlink when the documentation becomes available online.
Python 2.7 is planned to be the last of the 2.x releases, so we worked
on making it a good release for the long term. To help with porting
to Python 3, several new features from the Python 3.x series have been
included in 2.7.
Numeric handling has been improved in many ways, both for
floating-point numbers and for the :class:`Decimal` class. There are
some useful additions to the standard library, such as a greatly
enhanced :mod:`unittest` module, the :mod:`argparse` module for
parsing command-line options, convenient ordered-dictionary and
:class:`Counter` classes in the :mod:`collections` module, and many
other improvements.
This article doesn't attempt to provide a complete specification of
the new features, but instead provides a convenient overview. For
full details, you should refer to the documentation for Python 2.7 at
http://docs.python.org. If you want to understand the rationale for
the design and implementation, refer to the PEP for a particular new
feature or the issue on http://bugs.python.org in which a change was
discussed. Whenever possible, "What's New in Python" links to the
bug/patch item for each change.
.. _whatsnew27-python31:
@ -76,15 +93,16 @@ Two consequences of the long-term significance of 2.7 are:
* It's very likely the 2.7 release will have a longer period of
maintenance compared to earlier 2.x versions. Python 2.7 will
continue to be maintained while the transition to 3.x continues.
Maintenance releases for Python 2.7 will probably be made for 5
years.
continue to be maintained while the transition to 3.x continues, and
the developers are planning to support Python 2.7 with bug-fix
releases beyond the typical two years.
* A policy decision was made to silence warnings only of interest to
developers by default. :exc:`DeprecationWarning` and its
descendants are now ignored unless otherwise requested, preventing
users from seeing warnings triggered by an application. (Carried
out in :issue:`7319`.)
users from seeing warnings triggered by an application. This change
was also made in the branch that will become Python 3.2. (Discussed
on stdlib-sig and carried out in :issue:`7319`.)
In previous releases, :exc:`DeprecationWarning` messages were
enabled by default, providing Python developers with a clear
@ -100,8 +118,10 @@ Two consequences of the long-term significance of 2.7 are:
You can re-enable display of :exc:`DeprecationWarning` messages by
running Python with the :option:`-Wdefault` (short form:
:option:`-Wd`) switch, or you can add
``warnings.simplefilter('default')`` to your code.
:option:`-Wd`) switch, or by setting the :envvar:`PYTHONWARNINGS`
environment variable to ``"default"`` or ``"d"``) before running
Python. Python code can also re-enable them
by calling ``warnings.simplefilter('default')``.
Python 3.1 Features
@ -114,6 +134,9 @@ for migrating to the 3.x series.
A partial list of 3.1 features that were backported to 2.7:
* The syntax for set literals (``{1,2,3}`` is a mutable set).
* Dictionary and set comprehensions (``{ i: i*2 for i in range(3)}``).
* Multiple context managers in
* A new version of the :mod:`io` library, rewritten in C for performance.
* The ordered-dictionary type described in :ref:`pep-0372`.
* The new format specifier described in :ref:`pep-0378`.
@ -602,9 +625,9 @@ Some smaller changes made to the core Python language are:
3.x, generalizing list/generator comprehensions to use
the literal syntax for sets and dictionaries.
>>> {x:x*x for x in range(6)}
>>> {x: x*x for x in range(6)}
{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
>>> {'a'*x for x in range(6)}
>>> {('a'*x) for x in range(6)}
set(['', 'a', 'aa', 'aaa', 'aaaa', 'aaaaa'])
Backported by Alexandre Vassalotti; :issue:`2333`.
@ -2368,5 +2391,6 @@ Acknowledgements
The author would like to thank the following people for offering
suggestions, corrections and assistance with various drafts of this
article: Nick Coghlan, Ryan Lovett, R. David Murray, Hugh Secker-Walker.
article: Nick Coghlan, Philip Jenvey, Ryan Lovett, R. David Murray,
Hugh Secker-Walker.