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237 lines
8.5 KiB
ReStructuredText
****************************
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What's New in Python 2.6
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****************************
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:Author: A.M. Kuchling
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:Release: |release|
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:Date: |today|
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.. % $Id: whatsnew26.tex 55963 2007-06-13 18:07:49Z guido.van.rossum $
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.. % Rules for maintenance:
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.. %
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.. % * Anyone can add text to this document. Do not spend very much time
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.. % on the wording of your changes, because your text will probably
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.. % get rewritten to some degree.
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.. %
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.. % * The maintainer will go through Misc/NEWS periodically and add
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.. % changes; it's therefore more important to add your changes to
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.. % Misc/NEWS than to this file.
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.. %
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.. % * This is not a complete list of every single change; completeness
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.. % is the purpose of Misc/NEWS. Some changes I consider too small
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.. % or esoteric to include. If such a change is added to the text,
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.. % I'll just remove it. (This is another reason you shouldn't spend
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.. % too much time on writing your addition.)
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.. %
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.. % * If you want to draw your new text to the attention of the
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.. % maintainer, add 'XXX' to the beginning of the paragraph or
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.. % section.
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.. %
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.. % * It's OK to just add a fragmentary note about a change. For
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.. % example: "XXX Describe the transmogrify() function added to the
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.. % socket module." The maintainer will research the change and
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.. % write the necessary text.
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.. %
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.. % * You can comment out your additions if you like, but it's not
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.. % necessary (especially when a final release is some months away).
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.. %
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.. % * Credit the author of a patch or bugfix. Just the name is
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.. % sufficient; the e-mail address isn't necessary.
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.. %
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.. % * It's helpful to add the bug/patch number as a comment:
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.. %
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.. % % Patch 12345
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.. % XXX Describe the transmogrify() function added to the socket
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.. % module.
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.. % (Contributed by P.Y. Developer.)
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.. %
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.. % This saves the maintainer the effort of going through the SVN log
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.. % when researching a change.
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This article explains the new features in Python 2.6. No release date for
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Python 2.6 has been set; it will probably be released in mid 2008.
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This article doesn't attempt to provide a complete specification of the new
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features, but instead provides a convenient overview. For full details, you
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should refer to the documentation for Python 2.6. If you want to understand the
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complete implementation and design rationale, refer to the PEP for a particular
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new feature.
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.. % Compare with previous release in 2 - 3 sentences here.
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.. % add hyperlink when the documentation becomes available online.
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.. % ======================================================================
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.. % Large, PEP-level features and changes should be described here.
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.. % Should there be a new section here for 3k migration?
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.. % Or perhaps a more general section describing module changes/deprecation?
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.. % sets module deprecated
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.. % ======================================================================
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Other Language Changes
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======================
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Here are all of the changes that Python 2.6 makes to the core Python language.
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* An obscure change: when you use the the :func:`locals` function inside a
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:keyword:`class` statement, the resulting dictionary no longer returns free
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variables. (Free variables, in this case, are variables referred to in the
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:keyword:`class` statement that aren't attributes of the class.)
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.. % ======================================================================
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Optimizations
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-------------
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* Internally, a bit is now set in type objects to indicate some of the standard
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built-in types. This speeds up checking if an object is a subclass of one of
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these types. (Contributed by Neal Norwitz.)
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The net result of the 2.6 optimizations is that Python 2.6 runs the pystone
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benchmark around XX% faster than Python 2.5.
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.. % ======================================================================
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New, Improved, and Deprecated Modules
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=====================================
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As usual, Python's standard library received a number of enhancements and bug
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fixes. Here's a partial list of the most notable changes, sorted alphabetically
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by module name. Consult the :file:`Misc/NEWS` file in the source tree for a more
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complete list of changes, or look through the CVS logs for all the details.
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* A new data type in the :mod:`collections` module: :class:`NamedTuple(typename,
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fieldnames)` is a factory function that creates subclasses of the standard tuple
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whose fields are accessible by name as well as index. For example::
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var_type = collections.NamedTuple('variable',
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'id name type size')
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var = var_type(1, 'frequency', 'int', 4)
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print var[0], var.id # Equivalent
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print var[2], var.type # Equivalent
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(Contributed by Raymond Hettinger.)
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* A new method in the :mod:`curses` module: for a window, :meth:`chgat` changes
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the display characters for a certain number of characters on a single line. ::
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# Boldface text starting at y=0,x=21
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# and affecting the rest of the line.
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stdscr.chgat(0,21, curses.A_BOLD)
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(Contributed by Fabian Kreutz.)
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* The :func:`glob.glob` function can now return Unicode filenames if
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a Unicode path was used and Unicode filenames are matched within the directory.
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.. % Patch #1001604
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* The :mod:`gopherlib` module has been removed.
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* A new function in the :mod:`heapq` module: ``merge(iter1, iter2, ...)``
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takes any number of iterables that return data *in sorted order*, and returns
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a new iterator that returns the contents of all the iterators, also in sorted
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order. For example::
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heapq.merge([1, 3, 5, 9], [2, 8, 16]) ->
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[1, 2, 3, 5, 8, 9, 16]
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(Contributed by Raymond Hettinger.)
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* A new function in the :mod:`itertools` module: ``izip_longest(iter1, iter2,
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...[, fillvalue])`` makes tuples from each of the elements; if some of the
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iterables are shorter than others, the missing values are set to *fillvalue*.
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For example::
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itertools.izip_longest([1,2,3], [1,2,3,4,5]) ->
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[(1, 1), (2, 2), (3, 3), (None, 4), (None, 5)]
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(Contributed by Raymond Hettinger.)
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* The :mod:`macfs` module has been removed. This in turn required the
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:func:`macostools.touched` function to be removed because it depended on the
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:mod:`macfs` module.
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.. % Patch #1490190
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* New functions in the :mod:`posix` module: :func:`chflags` and :func:`lchflags`
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are wrappers for the corresponding system calls (where they're available).
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Constants for the flag values are defined in the :mod:`stat` module; some
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possible values include :const:`UF_IMMUTABLE` to signal the file may not be
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changed and :const:`UF_APPEND` to indicate that data can only be appended to the
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file. (Contributed by M. Levinson.)
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* The :mod:`rgbimg` module has been removed.
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* The :mod:`smtplib` module now supports SMTP over SSL thanks to the addition
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of the :class:`SMTP_SSL` class. This class supports an interface identical to
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the existing :class:`SMTP` class. (Contributed by Monty Taylor.)
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* The :mod:`test.test_support` module now contains a :func:`EnvironmentVarGuard`
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context manager that supports temporarily changing environment variables and
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automatically restores them to their old values. (Contributed by Brett Cannon.)
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.. % ======================================================================
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.. % whole new modules get described in \subsections here
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.. % ======================================================================
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Build and C API Changes
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=======================
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Changes to Python's build process and to the C API include:
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* Detailed changes are listed here.
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.. % ======================================================================
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Port-Specific Changes
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---------------------
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Platform-specific changes go here.
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.. % ======================================================================
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.. _section-other:
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Other Changes and Fixes
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=======================
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As usual, there were a bunch of other improvements and bugfixes scattered
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throughout the source tree. A search through the change logs finds there were
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XXX patches applied and YYY bugs fixed between Python 2.5 and 2.6. Both figures
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are likely to be underestimates.
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Some of the more notable changes are:
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* Details go here.
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.. % ======================================================================
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Porting to Python 2.6
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=====================
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This section lists previously described changes that may require changes to your
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code:
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* Everything is all in the details!
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.. % ======================================================================
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.. _acks:
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Acknowledgements
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================
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The author would like to thank the following people for offering suggestions,
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corrections and assistance with various drafts of this article: .
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