| **************************** |
| What's New in Python 2.6 |
| **************************** |
| |
| :Author: A.M. Kuchling |
| :Release: |release| |
| :Date: |today| |
| |
| .. % $Id: whatsnew26.tex 55963 2007-06-13 18:07:49Z guido.van.rossum $ |
| .. % 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 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. |
| |
| This article explains the new features in Python 2.6. No release date for |
| Python 2.6 has been set; it will probably be released in mid 2008. |
| |
| 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 2.6. If you want to understand the |
| complete implementation and design rationale, refer to the PEP for a particular |
| new feature. |
| |
| .. % 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 |
| ====================== |
| |
| Here are all of the changes that Python 2.6 makes to the core Python language. |
| |
| * The :func:`complex` constructor now accepts strings containing |
| parenthesized complex numbers, letting ``complex(repr(cmplx))`` |
| will now round-trip values. For example, ``complex('(3+4j)')`` |
| now returns the value (3+4j). |
| |
| .. % Patch 1491866 |
| |
| * The string :meth:`translate` method now accepts ``None`` as the |
| translation table parameter, which is treated as the identity |
| transformation. This makes it easier to carry out operations |
| that only delete characters. (Contributed by Bengt Richter.) |
| |
| .. % Patch 1193128 |
| |
| * An obscure change: when you use the the :func:`locals` function inside a |
| :keyword:`class` statement, the resulting dictionary no longer returns free |
| variables. (Free variables, in this case, are variables referred to in the |
| :keyword:`class` statement that aren't attributes of the class.) |
| |
| .. % ====================================================================== |
| |
| |
| Optimizations |
| ------------- |
| |
| * Internally, a bit is now set in type objects to indicate some of the standard |
| built-in types. This speeds up checking if an object is a subclass of one of |
| these types. (Contributed by Neal Norwitz.) |
| |
| The net result of the 2.6 optimizations is that Python 2.6 runs the pystone |
| benchmark around XX% faster than Python 2.5. |
| |
| .. % ====================================================================== |
| |
| |
| New, Improved, and Deprecated Modules |
| ===================================== |
| |
| As usual, 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 CVS logs for all the details. |
| |
| * A new data type in the :mod:`collections` module: :class:`NamedTuple(typename, |
| fieldnames)` is a factory function that creates subclasses of the standard tuple |
| whose fields are accessible by name as well as index. For example:: |
| |
| var_type = collections.NamedTuple('variable', |
| 'id name type size') |
| var = var_type(1, 'frequency', 'int', 4) |
| |
| print var[0], var.id # Equivalent |
| print var[2], var.type # Equivalent |
| |
| (Contributed by Raymond Hettinger.) |
| |
| * A new method in the :mod:`curses` module: for a window, :meth:`chgat` changes |
| the display characters for a certain number of characters on a single line. :: |
| |
| # Boldface text starting at y=0,x=21 |
| # and affecting the rest of the line. |
| stdscr.chgat(0,21, curses.A_BOLD) |
| |
| (Contributed by Fabian Kreutz.) |
| |
| * An optional ``timeout`` parameter was added to the |
| :class:`ftplib.FTP` class constructor as well as the :meth:`connect` |
| method, specifying a timeout measured in seconds. (Added by Facundo |
| Batista.) |
| |
| * The :func:`glob.glob` function can now return Unicode filenames if |
| a Unicode path was used and Unicode filenames are matched within the directory. |
| |
| .. % Patch #1001604 |
| |
| * The :mod:`gopherlib` module has been removed. |
| |
| * A new function in the :mod:`heapq` module: ``merge(iter1, iter2, ...)`` |
| takes any number of iterables that return data *in sorted order*, and returns |
| a new iterator that returns the contents of all the iterators, also in sorted |
| order. For example:: |
| |
| heapq.merge([1, 3, 5, 9], [2, 8, 16]) -> |
| [1, 2, 3, 5, 8, 9, 16] |
| |
| (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:: |
| |
| 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.) |
| |
| * The :mod:`macfs` module has been removed. This in turn required the |
| :func:`macostools.touched` function to be removed because it depended on the |
| :mod:`macfs` module. |
| |
| .. % Patch #1490190 |
| |
| * In the :mod:`os.path` module, the :func:`splitext` function |
| has been changed to not split on leading period characters. |
| This produces better results when operating on Unix's dot-files. |
| For example, ``os.path.splitext('.ipython')`` |
| now returns ``('.ipython', '')`` instead of ``('', '.ipython')``. |
| |
| .. % Bug #115886 |
| |
| A new function, :func:`relpath(path, start)` returns a relative path |
| from the ``start`` path, if it's supplied, or from the current |
| working directory to the destination ``path``. (Contributed by |
| Richard Barran.) |
| |
| .. % Patch 1339796 |
| |
| * 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 |
| possible values include :const:`UF_IMMUTABLE` to signal the file may not be |
| changed and :const:`UF_APPEND` to indicate that data can only be appended to the |
| file. (Contributed by M. Levinson.) |
| |
| * The :mod:`rgbimg` module has been removed. |
| |
| * 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 |
| class constructors also have an optional ``timeout`` parameter |
| that specifies a timeout for the initial connection attempt, measured in |
| seconds. |
| |
| An implementation of the LMTP protocol (:rfc:`2033`) was also added to |
| the module. LMTP is used in place of SMTP when transferring e-mail |
| between agents that don't manage a mail queue. |
| |
| (SMTP over SSL contributed by Monty Taylor; timeout parameter |
| added by Facundo Batista; LMTP implemented by Leif |
| Hedstrom.) |
| |
| .. % Patch #957003 |
| |
| * An optional ``timeout`` parameter was added to the |
| :class:`telnetlib.Telnet` class constructor, specifying a timeout |
| measured in seconds. (Added by Facundo Batista.) |
| |
| * The :mod:`test.test_support` module now contains a :func:`EnvironmentVarGuard` |
| context manager that supports temporarily changing environment variables and |
| automatically restores them to their old values. (Contributed by Brett Cannon.) |
| |
| * The :mod:`timeit` module now accepts callables as well as strings |
| for the statement being timed and for the setup code. |
| Two convenience functions were added for creating |
| :class:`Timer` instances: |
| ``repeat(stmt, setup, time, repeat, number)`` and |
| ``timeit(stmt, setup, time, number)`` create an instance and call |
| the corresponding method. (Contributed by Erik Demaine.) |
| |
| .. % Patch #1533909 |
| |
| .. % ====================================================================== |
| .. % 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: |
| |
| * Detailed changes are listed here. |
| |
| .. % ====================================================================== |
| |
| |
| Port-Specific Changes |
| --------------------- |
| |
| Platform-specific changes go here. |
| |
| .. % ====================================================================== |
| |
| |
| .. _section-other: |
| |
| Other Changes and Fixes |
| ======================= |
| |
| As usual, there were a bunch of other improvements and bugfixes scattered |
| throughout the source tree. A search through the change logs finds there were |
| XXX patches applied and YYY bugs fixed between Python 2.5 and 2.6. Both figures |
| are likely to be underestimates. |
| |
| Some of the more notable changes are: |
| |
| * Details go here. |
| |
| .. % ====================================================================== |
| |
| |
| Porting to Python 2.6 |
| ===================== |
| |
| This section lists previously described changes that may require changes to your |
| code: |
| |
| * Everything is all in the details! |
| |
| .. % ====================================================================== |
| |
| |
| .. _acks: |
| |
| Acknowledgements |
| ================ |
| |
| The author would like to thank the following people for offering suggestions, |
| corrections and assistance with various drafts of this article: . |
| |