mirror of
https://github.com/python/cpython.git
synced 2024-11-30 18:51:15 +01:00
139 lines
4.9 KiB
ReStructuredText
139 lines
4.9 KiB
ReStructuredText
****************************
|
|
What's New In Python 3.1
|
|
****************************
|
|
|
|
.. XXX Add trademark info for Apple, Microsoft.
|
|
|
|
:Author: No one so far
|
|
: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. (Note: I didn't get to this for 3.0.
|
|
GvR.)
|
|
|
|
* 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. (Due to time
|
|
constraints I haven't managed to do this for 3.0. GvR.)
|
|
|
|
* It's helpful to add the bug/patch number as a comment:
|
|
|
|
% Patch 12345
|
|
XXX Describe the transmogrify() function added to the socket
|
|
module.
|
|
(Contributed by P.Y. Developer.)
|
|
|
|
This saves the maintainer the effort of going through the SVN log
|
|
when researching a change. (Again, I didn't get to this for 3.0.
|
|
GvR.)
|
|
|
|
This article explains the new features in Python 3.1, compared to 3.0.
|
|
|
|
.. 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?
|
|
.. sets module deprecated
|
|
.. ======================================================================
|
|
|
|
|
|
Other Language Changes
|
|
======================
|
|
|
|
Some smaller changes made to the core Python language are:
|
|
|
|
* The :func:`int` type 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`.)
|
|
|
|
* Integers are now stored internally either in base 2**15 or in base
|
|
2**30, the base being determined at build time. Previously, they
|
|
were always stored in base 2**15. Using base 2**30 gives
|
|
significant performance improvements on 64-bit machines, but
|
|
benchmark results on 32-bit machines have been mixed. Therefore,
|
|
the default is to use base 2**30 on 64-bit machines and base 2**15
|
|
on 32-bit machines; on Unix, there's a new configure option
|
|
--enable-big-digits that can be used to override this default.
|
|
|
|
Apart from the performance improvements this change should be
|
|
invisible to end users, with one exception: for testing and
|
|
debugging purposes there's a new structseq ``sys.int_info`` that
|
|
provides information about the internal format, giving the number of
|
|
bits per digit and the size in bytes of the C type used to store
|
|
each digit::
|
|
|
|
>>> import sys
|
|
>>> sys.int_info
|
|
sys.int_info(bits_per_digit=30, sizeof_digit=4)
|
|
|
|
|
|
(Contributed by Mark Dickinson; :issue:`4258`.)
|
|
|
|
|
|
.. ======================================================================
|
|
|
|
|
|
Optimizations
|
|
-------------
|
|
|
|
Major performance enhancements have been added:
|
|
|
|
* The new I/O library (as defined in :pep:`3116`) was mostly written in
|
|
Python and quickly proved to be a problematic bottleneck in Python 3.0.
|
|
In Python 3.1, the I/O library has been entirely rewritten in C and is
|
|
2 to 20 times faster depending on the task at hand. The pure Python
|
|
version is still available for experimentation purposes through
|
|
the ``_pyio`` module.
|
|
|
|
(Contributed by Amaury Forgeot d'Arc and Antoine Pitrou.)
|
|
|
|
* A new configure flag, ``--with-computed-gotos``, enables a faster opcode
|
|
dispatch mechanism on compilers which support it. Speedups of up to 20%
|
|
have been observed, depending on the system and compiler.
|
|
|
|
(Contributed by Antoine Pitrou, :issue:`4753`.)
|
|
|
|
|
|
.. ======================================================================
|