2003-07-30 16:14:09 -03:00
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\documentclass{howto}
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\usepackage{distutils}
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% $Id$
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\title{What's New in Python 2.4}
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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 2.4. No release date
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for Python 2.4 has been set; expect that this will happen in 2004.
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While Python 2.3 was primarily a library development release, Python
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2.4 may extend the core language and interpreter in
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as-yet-undetermined ways.
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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 2.4.
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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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%======================================================================
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\section{Other Language Changes}
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Here are all of the changes that Python 2.4 makes to the core Python
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language.
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\begin{itemize}
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2003-10-21 09:31:16 -03:00
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\item The \method{sort()} method of lists gained three keyword
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arguments, \var{cmp}, \var{key}, and \var{reverse}. These arguments
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make some common usages of \method{sort()} simpler. All are optional.
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\var{cmp} is the same as the previous single argument to
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\method{sort()}; if provided, the value should be a comparison
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function that takes two arguments and returns -1, 0, or +1 depending
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on how the arguments compare.
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\var{key} should be a single-argument function that takes a list
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element and returns a comparison key for the element. The list is
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then sorted using the comparison keys. The following example sorts a list
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case-insensitively:
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\begin{verbatim}
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>>> L = ['A', 'b', 'c', 'D']
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>>> L.sort() # Case-sensitive sort
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>>> L
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['A', 'D', 'b', 'c']
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>>> L.sort(key=lambda x: x.lower())
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>>> L
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['A', 'b', 'c', 'D']
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>>> L.sort(cmp=lambda x,y: cmp(x.lower(), y.lower()))
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>>> L
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['A', 'b', 'c', 'D']
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\end{verbatim}
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The last example, which uses the \var{cmp} parameter, is the old way
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to perform a case-insensitive sort. It works, but is slower than
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using a \var{key} parameter. Using \var{key} results in calling the
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\method{lower()} method once for each element in the list while using
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\var{cmp} will call the method twice for each comparison.
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The \var{reverse} parameter should have a Boolean value. If the value is
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\constant{True}, the list will be sorted into reverse order. Instead
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of \code{L.sort() ; L.reverse()}, you can now write
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\code{L.sort(reverse=True)}.
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2003-07-30 16:14:09 -03:00
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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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\item Optimizations should be described here.
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\end{itemize}
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The net result of the 2.4 optimizations is that Python 2.4 runs the
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pystone benchmark around XX\% faster than Python 2.3 and YY\% faster
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than Python 2.2.
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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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2003-08-13 20:11:04 -03:00
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\item The \module{curses} modules now supports the ncurses extension
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\function{use_default_colors()}. On platforms where the terminal
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supports transparency, this makes it possible to use a transparent background.
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(Contributed by J\"org Lehmann.)
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2003-07-30 16:14:09 -03:00
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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 CVS change
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logs finds there were XXX patches applied and YYY bugs fixed between
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Python 2.3 and 2.4. 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 2.4}
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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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2003-09-20 12:52:21 -03:00
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\item dircache.listdir now passes exceptions to the caller,
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instead of returning empty lists.
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2003-07-30 16:14:09 -03:00
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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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