209 lines
6.3 KiB
TeX
209 lines
6.3 KiB
TeX
\documentclass{howto}
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\usepackage{distutils}
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% $Id$
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\title{What's New in Python 2.6}
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\release{0.0}
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\author{A.M. Kuchling}
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\authoraddress{\email{amk@amk.ca}}
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\begin{document}
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\maketitle
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\tableofcontents
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This article explains the new features in Python 2.6. No release date
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for Python 2.6 has been set; it will probably be released in late 2007.
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% Compare with previous release in 2 - 3 sentences here.
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This article doesn't attempt to provide a complete specification of
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the new features, but instead provides a convenient overview. For
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full details, you should refer to the documentation for Python 2.6.
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% add hyperlink when the documentation becomes available online.
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If you want to understand the complete implementation and design
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rationale, refer to the PEP for a particular new feature.
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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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\section{Other Language Changes}
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Here are all of the changes that Python 2.6 makes to the core Python
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language.
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\begin{itemize}
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% Bug 1569356
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\item An obscure change: when you use the the \function{locals()}
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function inside a \keyword{class} statement, the resulting dictionary
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no longer returns free variables. (Free variables, in this case, are
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variables referred to in the \keyword{class} statement
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that aren't attributes of the class.)
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\end{itemize}
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%======================================================================
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\subsection{Optimizations}
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\begin{itemize}
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% Patch 1624059
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\item Internally, a bit is now set in type objects to indicate some of
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the standard built-in types. This speeds up checking if an object is
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a subclass of one of these types. (Contributed by Neal Norwitz.)
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\end{itemize}
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The net result of the 2.6 optimizations is that Python 2.6 runs the
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pystone benchmark around XX\% faster than Python 2.5.
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%======================================================================
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\section{New, Improved, and Deprecated Modules}
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As usual, Python's standard library received a number of enhancements and
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bug fixes. Here's a partial list of the most notable changes, sorted
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alphabetically by module name. Consult the
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\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
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details.
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\begin{itemize}
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\item New data type in the \module{collections} module:
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\class{NamedTuple(\var{typename}, \var{fieldnames})} is a factory function that
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creates subclasses of the standard tuple whose fields are accessible
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by name as well as index. For example:
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\begin{verbatim}
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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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\end{verbatim}
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(Contributed by Raymond Hettinger.)
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\item New function in the \module{heapq} module:
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\function{merge(iter1, iter2, ...)}
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takes any number of iterables that return data
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\emph{in sorted order},
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and
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returns a new iterator that returns the contents of
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all the iterators, also in sorted order. For example:
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\begin{verbatim}
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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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\end{verbatim}
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(Contributed by Raymond Hettinger.)
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\item New function in the \module{itertools} module:
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\function{izip_longest(iter1, iter2, ...\optional{, fillvalue})}
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makes tuples from each of the elements; if some of the iterables
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are shorter than others, the missing values
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are set to \var{fillvalue}. For example:
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\begin{verbatim}
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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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\end{verbatim}
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(Contributed by Raymond Hettinger.)
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% Patch #1490190
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\item New functions in the \module{posix} module: \function{chflags()}
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and \function{lchflags()} are wrappers for the corresponding system
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calls (where they're available). Constants for the flag values are
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defined in the \module{stat} module; some possible values include
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\constant{UF_IMMUTABLE} to signal the file may not be changed and
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\constant{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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\item The \module{smtplib} module now supports SMTP over
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SSL thanks to the addition of the \class{SMTP_SSL} class.
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This class supports an interface identical to the existing \class{SMTP}
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class. (Contributed by Monty Taylor.)
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\item The \module{test.test_support} module now contains a
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\function{EnvironmentVarGuard} context manager that
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supports temporarily changing environment variables and
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automatically restores them to their old values.
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(Contributed by Brett Cannon.)
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\end{itemize}
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%======================================================================
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% whole new modules get described in \subsections here
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% ======================================================================
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\section{Build and C API Changes}
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Changes to Python's build process and to the C API include:
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\begin{itemize}
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\item Detailed changes are listed here.
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\end{itemize}
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%======================================================================
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\subsection{Port-Specific Changes}
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Platform-specific changes go here.
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%======================================================================
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\section{Other Changes and Fixes \label{section-other}}
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As usual, there were a bunch of other improvements and bugfixes
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scattered throughout the source tree. A search through the change
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logs finds there were XXX patches applied and YYY bugs fixed between
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Python 2.5 and 2.6. Both figures are likely to be underestimates.
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Some of the more notable changes are:
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\begin{itemize}
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\item Details go here.
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\end{itemize}
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%======================================================================
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\section{Porting to Python 2.6}
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This section lists previously described changes that may require
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changes to your code:
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\begin{itemize}
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\item Everything is all in the details!
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\end{itemize}
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%======================================================================
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\section{Acknowledgements \label{acks}}
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The author would like to thank the following people for offering
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suggestions, corrections and assistance with various drafts of this
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article: .
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\end{document}
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