[Python-checkins] python/dist/src/Doc/whatsnew whatsnew24.tex,, whatsnew25.tex,,

jhylton@users.sourceforge.net jhylton at users.sourceforge.net
Sun Oct 16 07:24:32 CEST 2005

Update of /cvsroot/python/python/dist/src/Doc/whatsnew
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv27718/Doc/whatsnew

Modified Files:
      Tag: ast-branch
	whatsnew24.tex whatsnew25.tex 
Log Message:
Merge head to branch (for the last time)

Index: whatsnew24.tex
RCS file: /cvsroot/python/python/dist/src/Doc/whatsnew/whatsnew24.tex,v
retrieving revision
retrieving revision
diff -u -d -r1.127.2.1 -r1.127.2.2
--- whatsnew24.tex	7 Jan 2005 06:57:40 -0000
+++ whatsnew24.tex	16 Oct 2005 05:23:58 -0000
@@ -18,8 +18,8 @@
-This article explains the new features in Python 2.4, released on
-November~30, 2004.
+This article explains the new features in Python 2.4.1, released on
+March~30, 2005.
 Python 2.4 is a medium-sized release.  It doesn't introduce as many
 changes as the radical Python 2.2, but introduces more features than
@@ -379,9 +379,11 @@
 by Kevin D. Smith, Jim Jewett, and Skip Montanaro.  Several people
 wrote patches implementing function decorators, but the one that was
 actually checked in was patch \#979728, written by Mark Russell.}
-% XXX add link to decorators module in Wiki
+{This Wiki page contains several examples of decorators.}
@@ -1039,7 +1041,7 @@
 \item The inner loops for list and tuple slicing
  were optimized and now run about one-third faster.  The inner loops
- for dictionaries were also optimized , resulting in performance boosts for
+ for dictionaries were also optimized, resulting in performance boosts for
  \method{keys()}, \method{values()}, \method{items()},
  \method{iterkeys()}, \method{itervalues()}, and \method{iteritems()}.
  (Contributed by Raymond Hettinger.)
@@ -1426,6 +1428,12 @@
 Python 2.4's regular expression engine can match this pattern without
+\item The \module{signal} module now performs tighter error-checking
+on the parameters to the \function{signal.signal()} function.  For
+example, you can't set a handler on the \constant{SIGKILL} signal;
+previous versions of Python would quietly accept this, but 2.4 will
+raise a \exception{RuntimeError} exception.
 \item Two new functions were added to the \module{socket} module.
 \function{socketpair()} returns a pair of connected sockets and
 \function{getservbyport(\var{port})} looks up the service name for a
@@ -1705,6 +1713,11 @@
   now return  an empty list instead of raising a \exception{TypeError}
   exception if called with no arguments.
+\item You can no longer compare the \class{date} and \class{datetime}
+  instances provided by the \module{datetime} module.  Two 
+  instances of different classes will now always be unequal, and 
+  relative comparisons (\code{<}, \code{>}) will raise a \exception{TypeError}.
 \item \function{dircache.listdir()} now passes exceptions to the caller
       instead of returning empty lists.
@@ -1724,8 +1737,10 @@
 \item \constant{None} is now a constant; code that binds a new value to 
 the name \samp{None} is now a syntax error.
-% signal module now raises a RuntimeError on insane calls - e.g. setting a 
-% handler on SIGKILL
+\item The \function{signals.signal()} function now raises a
+\exception{RuntimeError} exception for certain illegal values;
+previously these errors would pass silently.  For example, you can no
+longer set a handler on the \constant{SIGKILL} signal.
@@ -1735,7 +1750,8 @@
 The author would like to thank the following people for offering
 suggestions, corrections and assistance with various drafts of this
-article: Koray Can, Hye-Shik Chang, Michael Dyck, Raymond Hettinger, 
-Brian Hurt, Hamish Lawson, Fredrik Lundh, Sean Reifschneider.
+article: Koray Can, Hye-Shik Chang, Michael Dyck, Raymond Hettinger,
+Brian Hurt, Hamish Lawson, Fredrik Lundh, Sean Reifschneider,
+Sadruddin Rejeb.

Index: whatsnew25.tex
RCS file: /cvsroot/python/python/dist/src/Doc/whatsnew/whatsnew25.tex,v
retrieving revision
retrieving revision
diff -u -d -r1.4.2.1 -r1.4.2.2
--- whatsnew25.tex	7 Jan 2005 06:57:41 -0000
+++ whatsnew25.tex	16 Oct 2005 05:23:58 -0000
@@ -1,5 +1,6 @@
 % $Id$
@@ -26,8 +27,229 @@
+\section{PEP 309: Partial Function Application}
-% Large, PEP-level features and changes should be described here.
+The \module{functional} module is intended to contain tools for
+functional-style programming.  Currently it only contains
+\class{partial}, but new functions will probably be added in future
+versions of Python.
+For programs written in a functional style, it can be useful to
+construct variants of existing functions that have some of the
+parameters filled in.  Consider a Python function \code{f(a, b, c)};
+you could create a new function \code{g(b, c)} that was equivalent to
+\code{f(1, b, c)}.  This is called ``partial function application'',
+and is provided by the \class{partial} class in the new
+\module{functional} module.
+The constructor for \class{partial} takes the arguments
+\code{(\var{function}, \var{arg1}, \var{arg2}, ...
+\var{kwarg1}=\var{value1}, \var{kwarg2}=\var{value2})}.  The resulting
+object is callable, so you can just call it to invoke \var{function}
+with the filled-in arguments.
+Here's a small but realistic example:
+import functional
+def log (message, subsystem):
+    "Write the contents of 'message' to the specified subsystem."
+    print '%s: %s' % (subsystem, message)
+    ...
+server_log = functional.partial(log, subsystem='server')
+Here's another example, from a program that uses PyGTk.  Here a
+context-sensitive pop-up menu is being constructed dynamically.  The
+callback provided for the menu option is a partially applied version
+of the \method{open_item()} method, where the first argument has been
+class Application:
+    def open_item(self, path):
+       ...
+    def init (self):
+        open_func = functional.partial(self.open_item, item_path)
+        popup_menu.append( ("Open", open_func, 1) )
+\seepep{309}{Partial Function Application}{PEP proposed and written by
+Peter Harris; implemented by Hye-Shik Chang, with adaptations by
+Raymond Hettinger.}
+\section{PEP 314: Metadata for Python Software Packages v1.1}
+Some simple dependency support was added to Distutils.  The
+\function{setup()} function now has \code{requires},\code{provides},
+and \code{obsoletes}.  When you build a source distribution using the
+\code{sdist} command, the dependency information will be recorded in
+the \file{PKG-INFO} file.  
+Another new keyword is \code{download_url}, which should be set to a
+URL for the package's source code.  This means it's now possible to
+look up an entry in the package index, determine the dependencies for
+a package, and download the required packages.  
+% XXX put example here
+\seepep{314}{Metadata for Python Software Packages v1.1}{PEP proposed
+and written by A.M. Kuchling, Richard Jones, and Fred Drake; 
+implemented by Richard Jones and Fred Drake.}
+\section{PEP 342: New Generator Features}
+As introduced in Python 2.3, generators only produce output; once a
+generator's code was invoked to create an iterator, there's no way to
+pass new parameters into the function when its execution is resumed.
+Hackish solutions to this include making the generator's code look at
+a global variable and then changing the global variable's value, or
+passing in some mutable object that callers then modify.  Python
+2.5 adds the ability to pass values \emph{into} a generator.
+To refresh your memory of basic generators, here's a simple example:
+def counter (maximum):
+    i = 0
+    while i < maximum:
+        yield i
+	i += 1
+When you call \code{counter(10)}, the result is an iterator that
+returns the values from 0 up to 9.  On encountering the
+\keyword{yield} statement, the iterator returns the provided value and
+suspends the function's execution, preserving the local variables.
+Execution resumes on the following call to the iterator's 
+\method{next()} method, picking up after the \keyword{yield}.
+In Python 2.3, \keyword{yield} was a statement; it didn't return any
+value.  In 2.5, \keyword{yield} is now an expression, returning a
+value that can be assigned to a variable or otherwise operated on:
+val = (yield i)
+I recommend that you always put parentheses around a \keyword{yield}
+expression when you're doing something with the returned value, as in
+the above example.  The parentheses aren't always necessary, but it's
+easier to always add them instead of having to remember when they're
+needed.  The exact rules are that a \keyword{yield}-expression must
+always be parenthesized except when it occurs at the top-level
+expression on the right-hand side of an assignment, meaning
+you can to write \code{val = yield i} but \code{val = (yield i) + 12}.
+Values are sent into a generator by calling its
+\method{send(\var{value})} method.  The generator's code is then
+resumed and the \keyword{yield} expression produces \var{value}.
+If the regular \method{next()} method is called, the \keyword{yield} 
+returns \constant{None}.
+Here's the previous example, modified to allow changing the value of
+the internal counter.
+def counter (maximum):
+    i = 0
+    while i < maximum:
+        val = (yield i)
+	# If value provided, change counter
+        if val is not None:
+            i = val
+	else:
+  	    i += 1
+And here's an example of changing the counter:
+>>> it = counter(10)
+>>> print it.next()
+>>> print it.next()
+>>> print it.send(8)
+>>> print it.next()
+>>> print it.next()
+Traceback (most recent call last):
+  File ``t.py'', line 15, in ?
+    print it.next()
+Because \keyword{yield} will often be returning \constant{None}, 
+you shouldn't just use its value in expressions unless you're sure 
+that only the \method{send()} method will be used.
+There are two other new methods on generators in addition to 
+  \item \method{throw(\var{type}, \var{value}=None,
+  \var{traceback}=None)} is used to raise an exception inside the
+  generator; the exception is raised by the \keyword{yield} expression
+  where the generator's execution is paused.
+  \item \method{close()} raises a new \exception{GeneratorExit}
+  exception inside the generator to terminate the iteration.  
+  On receiving this
+  exception, the generator's code must either raise
+  \exception{GeneratorExit} or \exception{StopIteration}; catching the 
+  exception and doing anything else is illegal and will trigger
+  a \exception{RuntimeError}.  \method{close()} will also be called by 
+  Python's garbage collection when the generator is garbage-collected.
+  If you need to run cleanup code in case of a \exception{GeneratorExit},
+  I suggest using a \code{try: ... finally:} suite instead of 
+  catching \exception{GeneratorExit}.
+The cumulative effect of these changes is to turn generators from
+one-way producers of information into both producers and consumers.
+Generators also become \emph{coroutines}, a more generalized form of
+subroutines; subroutines are entered at one point and exited at
+another point (the top of the function, and a \keyword{return
+statement}), but coroutines can be entered, exited, and resumed at
+many different points (the \keyword{yield} statements).science term
+\seepep{342}{Coroutines via Enhanced Generators}{PEP written by 
+Guido van Rossum and Phillip J. Eby;
+implemented by Phillip J. Eby.  Includes examples of 
+some fancier uses of generators as coroutines.}
+\seeurl{http://en.wikipedia.org/wiki/Coroutine}{The Wikipedia entry for 
+explanation of coroutines from a Perl point of view, written by Dan
@@ -40,7 +262,7 @@
 \item The \function{min()} and \function{max()} built-in functions
 gained a \code{key} keyword argument analogous to the \code{key}
-argument for \function{sort()}.  This argument supplies a function
+argument for \method{sort()}.  This argument supplies a function
 that takes a single argument and is called for every value in the list; 
 \function{min()}/\function{max()} will return the element with the 
 smallest/largest return value from this function.
@@ -56,6 +278,25 @@
 (Contributed by Steven Bethard and Raymond Hettinger.)
+\item Two new built-in functions, \function{any()} and
+\function{all()}, evaluate whether an iterator contains any true or
+false values.  \function{any()} returns \constant{True} if any value
+returned by the iterator is true; otherwise it will return
+\constant{False}.  \function{all()} returns \constant{True} only if
+all of the values returned by the iterator evaluate as being true.
+% XXX who added?
+\item The list of base classes in a class definition can now be empty.  
+As an example, this is now legal:
+class C():
+    pass
+(Implemented by Brett Cannon.)
@@ -64,7 +305,12 @@
-\item Optimizations should be described here.
+\item When they were introduced 
+in Python 2.4, the built-in \class{set} and \class{frozenset} types
+were built on top of Python's dictionary type.  
+In 2.5 the internal data structure has been customized for implementing sets,
+and as a result sets will use a third less memory and are somewhat faster.
+(Implemented by Raymond Hettinger.)
@@ -84,14 +330,116 @@
-\item Descriptions go here.
+% collections.deque now has .remove()
+% the cPickle module no longer accepts the deprecated None option in the
+% args tuple returned by __reduce__().
+% csv module improvements
+% datetime.datetime() now has a strptime class method which can be used to
+% create datetime object using a string and format.
+\item A new \module{hashlib} module has been added to replace the
+\module{md5} and \module{sha} modules.  \module{hashlib} adds support
+for additional secure hashes (SHA-224, SHA-256, SHA-384, and SHA-512).
+When available, the module uses OpenSSL for fast platform optimized
+implementations of algorithms.  The old \module{md5} and \module{sha}
+modules still exist as wrappers around hashlib to preserve backwards
+compatibility.  (Contributed by Gregory P. Smith.)
+\item The \function{nsmallest()} and 
+\function{nlargest()} functions in the \module{heapq} module 
+now support a \code{key} keyword argument similar to the one
+provided by the \function{min()}/\function{max()} functions
+and the \method{sort()} methods.  For example:
+>>> import heapq
+>>> L = ["short", 'medium', 'longest', 'longer still']
+>>> heapq.nsmallest(2, L)  # Return two lowest elements, lexicographically
+['longer still', 'longest']
+>>> heapq.nsmallest(2, L, key=len)   # Return two shortest elements
+['short', 'medium']
+(Contributed by Raymond Hettinger.)
+\item The \function{itertools.islice()} function now accepts
+\code{None} for the start and step arguments.  This makes it more
+compatible with the attributes of slice objects, so that you can now write
+the following:
+s = slice(5)     # Create slice object
+itertools.islice(iterable, s.start, s.stop, s.step)
+(Contributed by Raymond Hettinger.)
+\item The \module{operator} module's \function{itemgetter()} 
+and \function{attrgetter()} functions now support multiple fields.  
+A call such as \code{operator.attrgetter('a', 'b')}
+will return a function 
+that retrieves the \member{a} and \member{b} attributes.  Combining 
+this new feature with the \method{sort()} method's \code{key} parameter 
+lets you easily sort lists using multiple fields.
+% XXX who added?
+\item The \module{os} module underwent a number of changes.  The
+\member{stat_float_times} variable now defaults to true, meaning that
+\function{os.stat()} will now return time values as floats.  (This
+doesn't necessarily mean that \function{os.stat()} will return times
+that are precise to fractions of a second; not all systems support
+such precision.)
+Constants named \member{os.SEEK_SET}, \member{os.SEEK_CUR}, and
+\member{os.SEEK_END} have been added; these are the parameters to the
+\function{os.lseek()} function.  Two new constants for locking are
+\member{os.O_SHLOCK} and \member{os.O_EXLOCK}.
+On FreeBSD, the \function{os.stat()} function now returns 
+times with nanosecond resolution, and the returned object
+now has \member{st_gen} and \member{st_birthtime}.
+The \member{st_flags} member is also available, if the platform supports it.
+% XXX patch 1180695, 1212117
+\item New module: \module{spwd} provides functions for accessing the
+shadow password database on systems that support it.  
+% XXX give example
+\item The \class{TarFile} class in the \module{tarfile} module now has
+an \method{extractall()} method that extracts all members from the
+archive into the current working directory.  It's also possible to set
+a different directory as the extraction target, and to unpack only a
+subset of the archive's members.  
+A tarfile's compression can be autodetected by 
+using the mode \code{'r|*'}.
+% patch 918101
+(Contributed by Lars Gust\"abel.)
+\item The \module{xmlrpclib} module now supports returning 
+      \class{datetime} objects for the XML-RPC date type.  Supply 
+      \code{use_datetime=True} to the \function{loads()} function
+      or the \class{Unmarshaller} class to enable this feature.
+% XXX patch 1120353
 % whole new modules get described in \subsections here
+% XXX new distutils features: upload
 % ======================================================================
 \section{Build and C API Changes}
@@ -100,8 +448,15 @@
-\item The \cfunction{PyRange_New()} function was removed.  It was never documented,
-never used in the core code, and had dangerously lax error checking.  
+\item The built-in set types now have an official C API.  Call
+\cfunction{PySet_New()} and \cfunction{PyFrozenSet_New()} to create a
+new set, \cfunction{PySet_Add()} and \cfunction{PySet_Discard()} to
+add and remove elements, and \cfunction{PySet_Contains} and
+\cfunction{PySet_Size} to examine the set's state.
+\item The \cfunction{PyRange_New()} function was removed.  It was
+never documented, never used in the core code, and had dangerously lax
+error checking.
@@ -137,7 +492,24 @@
-\item Everything is all in the details!
+\item Some old deprecated modules (\module{statcache}, \module{tzparse},
+      \module{whrandom})  have been moved to \file{Lib/lib-old}.
+You can get access to these modules  again by adding the directory 
+to your \code{sys.path}:
+import os
+from distutils import sysconfig
+lib_dir = sysconfig.get_python_lib(standard_lib=True)
+old_dir = os.path.join(lib_dir, 'lib-old')
+Doing so is discouraged, however; it's better to update any code that
+still uses these modules.
+% the pickle module no longer uses the deprecated bin parameter.

More information about the Python-checkins mailing list