mirror of https://github.com/python/cpython
2193 lines
89 KiB
Plaintext
2193 lines
89 KiB
Plaintext
+++++++++++
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Python News
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+++++++++++
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(editors: check NEWS.help for information about editing NEWS using ReST.)
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What's New in Python 2.3 alpha 1?
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=================================
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*XXX Release date: DD-MMM-2002 XXX*
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Type/class unification and new-style classes
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--------------------------------------------
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- Assignment to __class__ is disallowed if either the old and the new
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class is a statically allocated type object (such as defined by an
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extension module). This prevents anomalies like 2.__class__ = bool.
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- New-style object creation and deallocation have been sped up
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significantly; they are now faster than classic instance creation
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and deallocation.
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- The __slots__ variable can now mention "private" names, and the
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right thing will happen (e.g. __slots__ = ["__foo"]).
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- The built-ins slice() and buffer() are now callable types. The
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types classobj (formerly class), code, function, instance, and
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instancemethod (formerly instance-method), which have no built-in
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names but are accessible through the types module, are now also
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callable. The type dict-proxy is renamed to dictproxy.
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- Cycles going through the __class__ link of a new-style instance are
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now detected by the garbage collector.
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- Classes using __slots__ are now properly garbage collected.
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[SF bug 519621]
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- Tightened the __slots__ rules: a slot name must be a valid Python
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identifier.
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- The constructor for the module type now requires a name argument and
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takes an optional docstring argument. Previously, this constructor
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ignored its arguments. As a consequence, deriving a class from a
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module (not from the module type) is now illegal; previously this
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created an unnamed module, just like invoking the module type did.
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[SF bug 563060]
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- A new type object, 'basestring', is added. This is a common base type
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for 'str' and 'unicode', and can be used instead of
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types.StringTypes, e.g. to test whether something is "a string":
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isinstance(x, basestring) is True for Unicode and 8-bit strings. This
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is an abstract base class and cannot be instantiated directly.
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- Changed new-style class instantiation so that when C's __new__
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method returns something that's not a C instance, its __init__ is
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not called. [SF bug #537450]
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- Fixed super() to work correctly with class methods. [SF bug #535444]
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- If you try to pickle an instance of a class that has __slots__ but
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doesn't define or override __getstate__, a TypeError is now raised.
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This is done by adding a bozo __getstate__ to the class that always
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raises TypeError. (Before, this would appear to be pickled, but the
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state of the slots would be lost.)
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Core and builtins
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-----------------
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- Unicode file name processing for Windows (PEP 277) is implemented.
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All platforms now have an os.path.supports_unicode_filenames attribute,
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which is set to True on Windows NT/2000/XP, and False elsewhere.
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- Codec error handling callbacks (PEP 293) are implemented.
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Error handling in unicode.encode or str.decode can now be customized.
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- A subtle change to the semantics of the built-in function intern():
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interned strings are no longer immortal. You must keep a reference
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to the return value intern() around to get the benefit.
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- Use of 'None' as a variable, argument or attribute name now
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issues a SyntaxWarning. In the future, None may become a keyword.
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- SET_LINENO is gone. co_lnotab is now consulted to determine when to
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call the trace function. C code that accessed f_lineno should call
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PyCode_Addr2Line instead (f_lineno is still there, but not kept up
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to date).
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- There's a new warning category, FutureWarning. This is used to warn
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about a number of situations where the value or sign of an integer
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result will change in Python 2.4 as a result of PEP 237 (integer
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unification). The warnings implement stage B0 mentioned in that
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PEP. The warnings are about the following situations:
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- Octal and hex literals without 'L' prefix in the inclusive range
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[0x80000000..0xffffffff]; these are currently negative ints, but
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in Python 2.4 they will be positive longs with the same bit
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pattern.
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- Left shifts on integer values that cause the outcome to lose
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bits or have a different sign than the left operand. To be
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precise: x<<n where this currently doesn't yield the same value
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as long(x)<<n; in Python 2.4, the outcome will be long(x)<<n.
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- Conversions from ints to string that show negative values as
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unsigned ints in the inclusive range [0x80000000..0xffffffff];
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this affects the functions hex() and oct(), and the string
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formatting codes %u, %o, %x, and %X. In Python 2.4, these will
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show signed values (e.g. hex(-1) currently returns "0xffffffff";
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in Python 2.4 it will return "-0x1").
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- The bits manipulated under the cover by sys.setcheckinterval() have
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been changed. Both the check interval and the ticker used to be
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per-thread values. They are now just a pair of global variables. In
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addition, the default check interval was boosted from 10 to 100
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bytecode instructions. This may have some effect on systems that
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relied on the old default value. In particular, in multi-threaded
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applications which try to be highly responsive, response time will
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increase by some (perhaps imperceptible) amount.
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- When multiplying very large integers, a version of the so-called
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Karatsuba algorithm is now used. This is most effective if the
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inputs have roughly the same size. If they both have about N digits,
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Karatsuba multiplication has O(N**1.58) runtime (the exponent is
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log_base_2(3)) instead of the previous O(N**2). Measured results may
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be better or worse than that, depending on platform quirks. Besides
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the O() improvement in raw instruction count, the Karatsuba algorithm
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appears to have much better cache behavior on extremely large integers
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(starting in the ballpark of a million bits). Note that this is a
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simple implementation, and there's no intent here to compete with,
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e.g., GMP. It gives a very nice speedup when it applies, but a package
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devoted to fast large-integer arithmetic should run circles around it.
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- u'%c' will now raise a ValueError in case the argument is an
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integer outside the valid range of Unicode code point ordinals.
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- The tempfile module has been overhauled for enhanced security. The
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mktemp() function is now deprecated; new, safe replacements are
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mkstemp() (for files) and mkdtemp() (for directories), and the
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higher-level functions NamedTemporaryFile() and TemporaryFile().
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Use of some global variables in this module is also deprecated; the
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new functions have keyword arguments to provide the same
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functionality. All Lib, Tools and Demo modules that used the unsafe
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interfaces have been updated to use the safe replacements. Thanks
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to Zack Weinberg!
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- When x is an object whose class implements __mul__ and __rmul__,
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1.0*x would correctly invoke __rmul__, but 1*x would erroneously
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invoke __mul__. This was due to the sequence-repeat code in the int
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type. This has been fixed now.
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- Previously, "str1 in str2" required str1 to be a string of length 1.
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This restriction has been relaxed to allow str1 to be a string of
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any length. Thus "'el' in 'hello world'" returns True now.
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- File objects are now their own iterators. For a file f, iter(f) now
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returns f (unless f is closed), and f.next() is similar to
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f.readline() when EOF is not reached; however, f.next() uses a
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readahead buffer that messes up the file position, so mixing
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f.next() and f.readline() (or other methods) doesn't work right.
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Calling f.seek() drops the readahead buffer, but other operations
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don't. It so happens that this gives a nice additional speed boost
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to "for line in file:"; the xreadlines method and corresponding
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module are now obsolete. Thanks to Oren Tirosh!
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- Encoding declarations (PEP 263, phase 1) have been implemented. A
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comment of the form "# -*- coding: <encodingname> -*-" in the first
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or second line of a Python source file indicates the encoding.
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- list.sort() has a new implementation. While cross-platform results
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may vary, and in data-dependent ways, this is much faster on many
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kinds of partially ordered lists than the previous implementation,
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and reported to be just as fast on randomly ordered lists on
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several major platforms. This sort is also stable (if A==B and A
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precedes B in the list at the start, A precedes B after the sort too),
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although the language definition does not guarantee stability. A
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potential drawback is that list.sort() may require temp space of
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len(list)*2 bytes (``*4`` on a 64-bit machine). It's therefore possible
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for list.sort() to raise MemoryError now, even if a comparison function
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does not. See <http://www.python.org/sf/587076> for full details.
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- All standard iterators now ensure that, once StopIteration has been
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raised, all future calls to next() on the same iterator will also
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raise StopIteration. There used to be various counterexamples to
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this behavior, which could caused confusion or subtle program
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breakage, without any benefits. (Note that this is still an
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iterator's responsibility; the iterator framework does not enforce
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this.)
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- Ctrl+C handling on Windows has been made more consistent with
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other platforms. KeyboardInterrupt can now reliably be caught,
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and Ctrl+C at an interactive prompt no longer terminates the
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process under NT/2k/XP (it never did under Win9x). Ctrl+C will
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interrupt time.sleep() in the main thread, and any child processes
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created via the popen family (on win2k; we can't make win9x work
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reliably) are also interrupted (as generally happens on for Linux/Unix.)
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[SF bugs 231273, 439992 and 581232]
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- sys.getwindowsversion() has been added on Windows. This
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returns a tuple with information about the version of Windows
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currently running.
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- Slices and repetitions of buffer objects now consistently return
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a string. Formerly, strings would be returned most of the time,
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but a buffer object would be returned when the repetition count
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was one or when the slice range was all inclusive.
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- Unicode objects in sys.path are no longer ignored but treated
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as directory names.
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- Fixed string.startswith and string.endswith builtin methods
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so they accept negative indices. [SF bug 493951]
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- Fixed a bug with a continue inside a try block and a yield in the
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finally clause. [SF bug 567538]
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- Most builtin sequences now support "extended slices", i.e. slices
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with a third "stride" parameter. For example, "hello world"[::-1]
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gives "dlrow olleh".
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- A new warning PendingDeprecationWarning was added to provide
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direction on features which are in the process of being deprecated.
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The warning will not be printed by default. To see the pending
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deprecations, use -Walways::PendingDeprecationWarning::
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as a command line option or warnings.filterwarnings() in code.
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- Deprecated features of xrange objects have been removed as
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promised. The start, stop, and step attributes and the tolist()
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method no longer exist. xrange repetition and slicing have been
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removed.
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- New builtin function enumerate(x), from PEP 279. Example:
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enumerate("abc") is an iterator returning (0,"a"), (1,"b"), (2,"c").
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The argument can be an arbitrary iterable object.
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- The assert statement no longer tests __debug__ at runtime. This means
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that assert statements cannot be disabled by assigning a false value
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to __debug__.
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- A method zfill() was added to str and unicode, that fills a numeric
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string to the left with zeros. For example,
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"+123".zfill(6) -> "+00123".
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- Complex numbers supported divmod() and the // and % operators, but
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these make no sense. Since this was documented, they're being
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deprecated now.
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- String and unicode methods lstrip(), rstrip() and strip() now take
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an optional argument that specifies the characters to strip. For
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example, "Foo!!!?!?!?".rstrip("?!") -> "Foo".
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- Added a new dict method pop(key). This removes and returns the
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value corresponding to key. [SF patch #539949]
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- A new built-in type, bool, has been added, as well as built-in
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names for its two values, True and False. Comparisons and sundry
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other operations that return a truth value have been changed to
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return a bool instead. Read PEP 285 for an explanation of why this
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is backward compatible.
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- Fixed two bugs reported as SF #535905: under certain conditions,
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deallocating a deeply nested structure could cause a segfault in the
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garbage collector, due to interaction with the "trashcan" code;
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access to the current frame during destruction of a local variable
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could access a pointer to freed memory.
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- The optional object allocator ("pymalloc") has been enabled by
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default. The recommended practice for memory allocation and
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deallocation has been streamlined. A header file is included,
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Misc/pymemcompat.h, which can be bundled with 3rd party extensions
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and lets them use the same API with Python versions from 1.5.2
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onwards.
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- PyErr_Display will provide file and line information for all exceptions
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that have an attribute print_file_and_line, not just SyntaxErrors.
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- The UTF-8 codec will now encode and decode Unicode surrogates
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correctly and without raising exceptions for unpaired ones.
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- Universal newlines (PEP 278) is implemented. Briefly, using 'U'
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instead of 'r' when opening a text file for reading changes the line
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ending convention so that any of '\r', '\r\n', and '\n' is
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recognized (even mixed in one file); all three are converted to
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'\n', the standard Python line end character.
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- file.xreadlines() now raises a ValueError if the file is closed:
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Previously, an xreadlines object was returned which would raise
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a ValueError when the xreadlines.next() method was called.
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- sys.exit() inadvertently allowed more than one argument.
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An exception will now be raised if more than one argument is used.
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Extension modules
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-----------------
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- readline now dynamically adjusts its input/output stream if
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sys.stdin/stdout changes.
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- The _tkinter module (and hence Tkinter) has dropped support for
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Tcl/Tk 8.0 and 8.1. Only Tcl/Tk versions 8.2, 8.3 and 8.4 are
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supported.
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- cPickle.BadPickleGet is now a class.
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- The time stamps in os.stat_result are floating point numbers
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after stat_float_times has been called.
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- If the size passed to mmap.mmap() is larger than the length of the
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file on non-Windows platforms, a ValueError is raised. [SF bug 585792]
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- The xreadlines module is slated for obsolescence.
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- The strptime function in the time module is now always available (a
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Python implementation is used when the C library doesn't define it).
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- The 'new' module is no longer an extension, but a Python module that
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only exists for backwards compatibility. Its contents are no longer
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functions but callable type objects.
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- The bsddb.*open functions can now take 'None' as a filename.
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This will create a temporary in-memory bsddb that won't be
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written to disk.
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- posix.lchown, posix.killpg, posix.mknod, and posix.getpgid have been
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added where available.
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- The locale module now exposes the C library's gettext interface.
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- A security hole ("double free") was found in zlib-1.1.3, a popular
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third party compression library used by some Python modules. The
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hole was quickly plugged in zlib-1.1.4, and the Windows build of
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Python now ships with zlib-1.1.4.
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- pwd, grp, and resource return enhanced tuples now, with symbolic
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field names.
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- array.array is now a type object. A new format character
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'u' indicates Py_UNICODE arrays. For those, .tounicode and
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.fromunicode methods are available. Arrays now support __iadd__
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and __imul__.
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- dl now builds on every system that has dlfcn.h. Failure in case
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of sizeof(int)!=sizeof(long)!=sizeof(void*) is delayed until dl.open
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is called.
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- signal.sigpending, signal.sigprocmask and signal.sigsuspend have
|
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been added where available.
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- The sys module acquired a new attribute, api_version, which evaluates
|
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to the value of the PYTHON_API_VERSION macro with which the
|
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interpreter was compiled.
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Library
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-------
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||
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- xml.sax.saxutils.unescape has been added, to replace entity references
|
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with their entity value.
|
||
|
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- Queue.Queue.{put,get} now support an optional timeout argument.
|
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|
||
- Various features of Tk 8.4 are exposed in Tkinter.py. The multiple
|
||
option of tkFileDialog is exposed as function askopenfile{,name}s.
|
||
|
||
- Various configure methods of Tkinter have been stream-lined, so that
|
||
tag_configure, image_configure, window_configure now return a
|
||
dictionary when invoked with no argument.
|
||
|
||
- Importing the readline module now no longer has the side effect of
|
||
calling setlocale(LC_CTYPE, ""). The initial "C" locale, or
|
||
whatever locale is explicitly set by the user, is preserved. If you
|
||
want repr() of 8-bit strings in your preferred encoding to preserve
|
||
all printable characters of that encoding, you have to add the
|
||
following code to your $PYTHONSTARTUP file or to your application's
|
||
main():
|
||
|
||
import locale
|
||
locale.setlocale(locale.LC_CTYPE, "")
|
||
|
||
- shutil.move was added. shutil.copytree now reports errors as an
|
||
exception at the end, instead of printing error messages.
|
||
|
||
- Encoding name normalization was generalized to not only
|
||
replace hyphens with underscores, but also all other non-alphanumeric
|
||
characters (with the exception of the dot which is used for Python
|
||
package names during lookup). The aliases.py mapping was updated
|
||
to the new standard.
|
||
|
||
- mimetypes has two new functions: guess_all_extensions() which
|
||
returns a list of all known extensions for a mime type, and
|
||
add_type() which adds one mapping between a mime type and
|
||
an extension to the database.
|
||
|
||
- New module: sets, defines the class Set that implements a mutable
|
||
set type using the keys of a dict to represent the set. There's
|
||
also a class ImmutableSet which is useful when you need sets of sets
|
||
or when you need to use sets as dict keys, and a class BaseSet which
|
||
is the base class of the two. (This is not documented yet, but
|
||
help(sets) gives a wealth of information.)
|
||
|
||
- Added operator.pow(a,b) which is equivalent to a**b.
|
||
|
||
- random.randrange(-sys.maxint-1, sys.maxint) no longer raises
|
||
OverflowError. That is, it now accepts any combination of 'start'
|
||
and 'stop' arguments so long as each is in the range of Python's
|
||
bounded integers.
|
||
|
||
- New "algorithms" module: heapq, implements a heap queue. Thanks to
|
||
Kevin O'Connor for the code and Fran<61>ois Pinard for an entertaining
|
||
write-up explaining the theory and practical uses of heaps.
|
||
|
||
- New encoding for the Palm OS character set: palmos.
|
||
|
||
- binascii.crc32() and the zipfile module had problems on some 64-bit
|
||
platforms. These have been fixed. On a platform with 8-byte C longs,
|
||
crc32() now returns a signed-extended 4-byte result, so that its value
|
||
as a Python int is equal to the value computed a 32-bit platform.
|
||
|
||
- xml.dom.minidom.toxml and toprettyxml now take an optional encoding
|
||
argument.
|
||
|
||
- Some fixes in the copy module: when an object is copied through its
|
||
__reduce__ method, there was no check for a __setstate__ method on
|
||
the result [SF patch 565085]; deepcopy should treat instances of
|
||
custom metaclasses the same way it treats instances of type 'type'
|
||
[SF patch 560794].
|
||
|
||
- Sockets now support timeout mode. After s.settimeout(T), where T is
|
||
a float expressing seconds, subsequent operations raise an exception
|
||
if they cannot be completed within T seconds. To disable timeout
|
||
mode, use s.settimeout(None). There's also a module function,
|
||
socket.setdefaulttimeout(T), which sets the default for all sockets
|
||
created henceforth.
|
||
|
||
- getopt.gnu_getopt was added. This supports GNU-style option
|
||
processing, where options can be mixed with non-option arguments.
|
||
|
||
- Stop using strings for exceptions. String objects used for
|
||
exceptions are now classes deriving from Exception. The objects
|
||
changed were: Tkinter.TclError, bdb.BdbQuit, macpath.norm_error,
|
||
tabnanny.NannyNag, and xdrlib.Error.
|
||
|
||
- Constants BOM_UTF8, BOM_UTF16, BOM_UTF16_LE, BOM_UTF16_BE,
|
||
BOM_UTF32, BOM_UTF32_LE and BOM_UTF32_BE that represent the Byte
|
||
Order Mark in UTF-8, UTF-16 and UTF-32 encodings for little and
|
||
big endian systems were added to the codecs module. The old names
|
||
BOM32_* and BOM64_* were off by a factor of 2.
|
||
|
||
- Added conversion functions math.degrees() and math.radians().
|
||
|
||
- ftplib.retrlines() now tests for callback is None rather than testing
|
||
for False. Was causing an error when given a callback object which
|
||
was callable but also returned len() as zero. The change may
|
||
create new breakage if the caller relied on the undocumented behavior
|
||
and called with callback set to [] or some other False value not
|
||
identical to None.
|
||
|
||
- random.gauss() uses a piece of hidden state used by nothing else,
|
||
and the .seed() and .whseed() methods failed to reset it. In other
|
||
words, setting the seed didn't completely determine the sequence of
|
||
results produced by random.gauss(). It does now. Programs repeatedly
|
||
mixing calls to a seed method with calls to gauss() may see different
|
||
results now.
|
||
|
||
- The pickle.Pickler class grew a clear_memo() method to mimic that
|
||
provided by cPickle.Pickler.
|
||
|
||
- difflib's SequenceMatcher class now does a dynamic analysis of
|
||
which elements are so frequent as to constitute noise. For
|
||
comparing files as sequences of lines, this generally works better
|
||
than the IS_LINE_JUNK function, and function ndiff's linejunk
|
||
argument defaults to None now as a result. A happy benefit is
|
||
that SequenceMatcher may run much faster now when applied
|
||
to large files with many duplicate lines (for example, C program
|
||
text with lots of repeated "}" and "return NULL;" lines).
|
||
|
||
- New Text.dump() method in Tkinter module.
|
||
|
||
- New distutils commands for building packagers were added to
|
||
support pkgtool on Solaris and swinstall on HP-UX.
|
||
|
||
- distutils now has a new abstract binary packager base class
|
||
command/bdist_packager, which simplifies writing packagers.
|
||
This will hopefully provide the missing bits to encourage
|
||
people to submit more packagers, e.g. for Debian, FreeBSD
|
||
and other systems.
|
||
|
||
- The UTF-16, -LE and -BE stream readers now raise a
|
||
NotImplementedError for all calls to .readline(). Previously, they
|
||
used to just produce garbage or fail with an encoding error --
|
||
UTF-16 is a 2-byte encoding and the C lib's line reading APIs don't
|
||
work well with these.
|
||
|
||
- compileall now supports quiet operation.
|
||
|
||
- The BaseHTTPServer now implements optional HTTP/1.1 persistent
|
||
connections.
|
||
|
||
- socket module: the SSL support was broken out of the main
|
||
_socket module C helper and placed into a new _ssl helper
|
||
which now gets imported by socket.py if available and working.
|
||
|
||
- encodings package: added aliases for all supported IANA character
|
||
sets
|
||
|
||
- ftplib: to safeguard the user's privacy, anonymous login will use
|
||
"anonymous@" as default password, rather than the real user and host
|
||
name.
|
||
|
||
- webbrowser: tightened up the command passed to os.system() so that
|
||
arbitrary shell code can't be executed because a bogus URL was
|
||
passed in.
|
||
|
||
- gettext.translation has an optional fallback argument, and
|
||
gettext.find an optional all argument. Translations will now fallback
|
||
on a per-message basis.
|
||
|
||
- distutils bdist commands now offer a --skip-build option.
|
||
|
||
- warnings.warn now accepts a Warning instance as first argument.
|
||
|
||
- The xml.sax.expatreader.ExpatParser class will no longer create
|
||
circular references by using itself as the locator that gets passed
|
||
to the content handler implementation. [SF bug #535474]
|
||
|
||
- The email.Parser.Parser class now properly parses strings regardless
|
||
of their line endings, which can be any of \r, \n, or \r\n (CR, LF,
|
||
or CRLF). Also, the Header class's constructor default arguments
|
||
has changed slightly so that an explicit maxlinelen value is always
|
||
honored.
|
||
|
||
Tools/Demos
|
||
-----------
|
||
|
||
- The SGI demos (Demo/sgi) have been removed. Nobody thought they
|
||
were interesting any more. (The SGI library modules and extensions
|
||
are still there; it is believed that at least some of these are
|
||
still used and useful.)
|
||
|
||
- IDLE supports the new encoding declarations (PEP 263); it can also
|
||
deal with legacy 8-bit files if they use the locale's encoding. It
|
||
allows non-ASCII strings in the interactive shell and executes them
|
||
in the locale's encoding.
|
||
|
||
- freeze.py now produces binaries which can import shared modules,
|
||
unlike before when this failed due to missing symbol exports in
|
||
the generated binary.
|
||
|
||
Build
|
||
-----
|
||
|
||
- The fpectl module is not built by default; it's dangerous or useless
|
||
except in the hands of experts.
|
||
|
||
- The public Python C API will generally be declared using PyAPI_FUNC
|
||
and PyAPI_DATA macros, while Python extension module init functions
|
||
will be declared with PyMODINIT_FUNC. DL_EXPORT/DL_IMPORT macros
|
||
are deprecated.
|
||
|
||
- A bug was fixed that could cause COUNT_ALLOCS builds to segfault, or
|
||
get into infinite loops, when a new-style class got garbage-collected.
|
||
Unfortunately, to avoid this, the way COUNT_ALLOCS works requires
|
||
that new-style classes be immortal in COUNT_ALLOCS builds. Note that
|
||
COUNT_ALLOCS is not enabled by default, in either release or debug
|
||
builds, and that new-style classes are immortal only in COUNT_ALLOCS
|
||
builds.
|
||
|
||
- Compiling out the cyclic garbage collector is no longer an option.
|
||
The old symbol WITH_CYCLE_GC is now ignored, and Python.h arranges
|
||
that it's always defined (for the benefit of any extension modules
|
||
that may be conditionalizing on it). A bonus is that any extension
|
||
type participating in cyclic gc can choose to participate in the
|
||
Py_TRASHCAN mechanism now too; in the absence of cyclic gc, this used
|
||
to require editing the core to teach the trashcan mechanism about the
|
||
new type.
|
||
|
||
- According to Annex F of the current C standard,
|
||
|
||
The Standard C macro HUGE_VAL and its float and long double analogs,
|
||
HUGE_VALF and HUGE_VALL, expand to expressions whose values are
|
||
positive infinities.
|
||
|
||
Python only uses the double HUGE_VAL, and only to #define its own symbol
|
||
Py_HUGE_VAL. Some platforms have incorrect definitions for HUGE_VAL.
|
||
pyport.h used to try to worm around that, but the workarounds triggered
|
||
other bugs on other platforms, so we gave up. If your platform defines
|
||
HUGE_VAL incorrectly, you'll need to #define Py_HUGE_VAL to something
|
||
that works on your platform. The only instance of this I'm sure about
|
||
is on an unknown subset of Cray systems, described here:
|
||
|
||
http://www.cray.com/swpubs/manuals/SN-2194_2.0/html-SN-2194_2.0/x3138.htm
|
||
|
||
Presumably 2.3a1 breaks such systems. If anyone uses such a system, help!
|
||
|
||
- The configure option --without-doc-strings can be used to remove the
|
||
doc strings from the builtin functions and modules; this reduces the
|
||
size of the executable.
|
||
|
||
- The universal newlines option (PEP 278) is on by default. On Unix
|
||
it can be disabled by passing --without-universal-newlines to the
|
||
configure script. On other platforms, remove
|
||
WITH_UNIVERSAL_NEWLINES from pyconfig.h.
|
||
|
||
- On Unix, a shared libpython2.3.so can be created with --enable-shared.
|
||
|
||
- All uses of the CACHE_HASH, INTERN_STRINGS, and DONT_SHARE_SHORT_STRINGS
|
||
preprocessor symbols were eliminated. The internal decisions they
|
||
controlled stopped being experimental long ago.
|
||
|
||
- The tools used to build the documentation now work under Cygwin as
|
||
well as Unix.
|
||
|
||
- The bsddb and dbm module builds have been changed to try and avoid version
|
||
skew problems and disable linkage with Berkeley DB 1.85 unless the
|
||
installer knows what s/he's doing. See the section on building these
|
||
modules in the README file for details.
|
||
|
||
C API
|
||
-----
|
||
|
||
- The string object's layout has changed: the pointer member
|
||
ob_sinterned has been replaced by an int member ob_sstate. On some
|
||
platforms (e.g. most 64-bit systems) this may change the offset of
|
||
the ob_sval member, so as a precaution the API_VERSION has been
|
||
incremented. The apparently unused feature of "indirect interned
|
||
strings", supported by the ob_sinterned member, is gone. Interned
|
||
strings are now usually mortal; theres a new API,
|
||
PyString_InternImmortal() that creates immortal interned strings.
|
||
(The ob_sstate member can only take three values; however, while
|
||
making it a char saves a few bytes per string object on average, in
|
||
it also slowed things down a bit because ob_sval was no longer
|
||
aligned.)
|
||
|
||
- The Py_InitModule*() functions now accept NULL for the 'methods'
|
||
argument. Modules without global functions are becoming more common
|
||
now that factories can be types rather than functions.
|
||
|
||
- New C API PyUnicode_FromOrdinal() which exposes unichr() at C
|
||
level.
|
||
|
||
- New functions PyErr_SetExcFromWindowsErr() and
|
||
PyErr_SetExcFromWindowsErrWithFilename(). Similar to
|
||
PyErr_SetFromWindowsErrWithFilename() and
|
||
PyErr_SetFromWindowsErr(), but they allow to specify
|
||
the exception type to raise. Available on Windows.
|
||
|
||
- Py_FatalError() is now declared as taking a const char* argument. It
|
||
was previously declared without const. This should not affect working
|
||
code.
|
||
|
||
- Added new macro PySequence_ITEM(o, i) that directly calls
|
||
sq_item without rechecking that o is a sequence and without
|
||
adjusting for negative indices.
|
||
|
||
- PyRange_New() now raises ValueError if the fourth argument is not 1.
|
||
This is part of the removal of deprecated features of the xrange
|
||
object.
|
||
|
||
- PyNumber_Coerce() and PyNumber_CoerceEx() now also invoke the type's
|
||
coercion if both arguments have the same type but this type has the
|
||
CHECKTYPES flag set. This is to better support proxies.
|
||
|
||
- The type of tp_free has been changed from "``void (*)(PyObject *)``" to
|
||
"``void (*)(void *)``".
|
||
|
||
- PyObject_Del, PyObject_GC_Del are now functions instead of macros.
|
||
|
||
- A type can now inherit its metatype from its base type. Previously,
|
||
when PyType_Ready() was called, if ob_type was found to be NULL, it
|
||
was always set to &PyType_Type; now it is set to base->ob_type,
|
||
where base is tp_base, defaulting to &PyObject_Type.
|
||
|
||
- PyType_Ready() accidentally did not inherit tp_is_gc; now it does.
|
||
|
||
- The PyCore_* family of APIs have been removed.
|
||
|
||
- The "u#" parser marker will now pass through Unicode objects as-is
|
||
without going through the buffer API.
|
||
|
||
- The enumerators of cmp_op have been renamed to use the prefix ``PyCmp_``.
|
||
|
||
- An old #define of ANY as void has been removed from pyport.h. This
|
||
hasn't been used since Python's pre-ANSI days, and the #define has
|
||
been marked as obsolete since then. SF bug 495548 says it created
|
||
conflicts with other packages, so keeping it around wasn't harmless.
|
||
|
||
- Because Python's magic number scheme broke on January 1st, we decided
|
||
to stop Python development. Thanks for all the fish!
|
||
|
||
- Some of us don't like fish, so we changed Python's magic number
|
||
scheme to a new one. See Python/import.c for details.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
- AtheOS is now supported.
|
||
|
||
- the EMX runtime environment on OS/2 is now supported.
|
||
|
||
- GNU/Hurd is now supported.
|
||
|
||
Tests
|
||
-----
|
||
|
||
Yet to be written.
|
||
|
||
Windows
|
||
-------
|
||
|
||
- Sometimes the uninstall executable (UNWISE.EXE) vanishes. One cause
|
||
of that has been fixed in the installer (disabled Wise's "delete in-
|
||
use files" uninstall option).
|
||
|
||
- Fixed a bug in urllib's proxy handling in Windows. [SF bug #503031]
|
||
|
||
- The installer now installs Start menu shortcuts under (the local
|
||
equivalent of) "All Users" when doing an Admin install.
|
||
|
||
- file.truncate([newsize]) now works on Windows for all newsize values.
|
||
It used to fail if newsize didn't fit in 32 bits, reflecting a
|
||
limitation of MS _chsize (which is no longer used).
|
||
|
||
- os.waitpid() is now implemented for Windows, and can be used to block
|
||
until a specified process exits. This is similar to, but not exactly
|
||
the same as, os.waitpid() on POSIX systems. If you're waiting for
|
||
a specific process whose pid was obtained from one of the spawn()
|
||
functions, the same Python os.waitpid() code works across platforms.
|
||
See the docs for details. The docs were changed to clarify that
|
||
spawn functions return, and waitpid requires, a process handle on
|
||
Windows (not the same thing as a Windows process id).
|
||
|
||
- New tempfile.TemporaryFile implementation for Windows: this doesn't
|
||
need a TemporaryFileWrapper wrapper anymore, and should be immune
|
||
to a nasty problem: before 2.3, if you got a temp file on Windows, it
|
||
got wrapped in an object whose close() method first closed the
|
||
underlying file, then deleted the file. This usually worked fine.
|
||
However, the spawn family of functions on Windows create (at a low C
|
||
level) the same set of open files in the spawned process Q as were
|
||
open in the spawning process P. If a temp file f was among them, then
|
||
doing f.close() in P first closed P's C-level file handle on f, but Q's
|
||
C-level file handle on f remained open, so the attempt in P to delete f
|
||
blew up with a "Permission denied" error (Windows doesn't allow
|
||
deleting open files). This was surprising, subtle, and difficult to
|
||
work around.
|
||
|
||
- The os module now exports all the symbolic constants usable with the
|
||
low-level os.open() on Windows: the new constants in 2.3 are
|
||
O_NOINHERIT, O_SHORT_LIVED, O_TEMPORARY, O_RANDOM and O_SEQUENTIAL.
|
||
The others were also available in 2.2: O_APPEND, O_BINARY, O_CREAT,
|
||
O_EXCL, O_RDONLY, O_RDWR, O_TEXT, O_TRUNC and O_WRONLY. Contrary
|
||
to Microsoft docs, O_SHORT_LIVED does not seem to imply O_TEMPORARY
|
||
(so specify both if you want both; note that neither is useful unless
|
||
specified with O_CREAT too).
|
||
|
||
Mac
|
||
----
|
||
|
||
Yet to be written.
|
||
|
||
|
||
What's New in Python 2.2 final?
|
||
===============================
|
||
|
||
*Release date: 21-Dec-2001*
|
||
|
||
Type/class unification and new-style classes
|
||
--------------------------------------------
|
||
|
||
- pickle.py, cPickle: allow pickling instances of new-style classes
|
||
with a custom metaclass.
|
||
|
||
Core and builtins
|
||
-----------------
|
||
|
||
- weakref proxy object: when comparing, unwrap both arguments if both
|
||
are proxies.
|
||
|
||
Extension modules
|
||
-----------------
|
||
|
||
- binascii.b2a_base64(): fix a potential buffer overrun when encoding
|
||
very short strings.
|
||
|
||
- cPickle: the obscure "fast" mode was suspected of causing stack
|
||
overflows on the Mac. Hopefully fixed this by setting the recursion
|
||
limit much smaller. If the limit is too low (it only affects
|
||
performance), you can change it by defining PY_CPICKLE_FAST_LIMIT
|
||
when compiling cPickle.c (or in pyconfig.h).
|
||
|
||
Library
|
||
-------
|
||
|
||
- dumbdbm.py: fixed a dumb old bug (the file didn't get synched at
|
||
close or delete time).
|
||
|
||
- rfc822.py: fixed a bug where the address '<>' was converted to None
|
||
instead of an empty string (also fixes the email.Utils module).
|
||
|
||
- xmlrpclib.py: version 1.0.0; uses precision for doubles.
|
||
|
||
- test suite: the pickle and cPickle tests were not executing any code
|
||
when run from the standard regression test.
|
||
|
||
Tools/Demos
|
||
-----------
|
||
|
||
Build
|
||
-----
|
||
|
||
C API
|
||
-----
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
Tests
|
||
-----
|
||
|
||
Windows
|
||
-------
|
||
|
||
- distutils package: fixed broken Windows installers (bdist_wininst).
|
||
|
||
- tempfile.py: prevent mysterious warnings when TemporaryFileWrapper
|
||
instances are deleted at process exit time.
|
||
|
||
- socket.py: prevent mysterious warnings when socket instances are
|
||
deleted at process exit time.
|
||
|
||
- posixmodule.c: fix a Windows crash with stat() of a filename ending
|
||
in backslash.
|
||
|
||
Mac
|
||
----
|
||
|
||
- The Carbon toolbox modules have been upgraded to Universal Headers
|
||
3.4, and experimental CoreGraphics and CarbonEvents modules have
|
||
been added. All only for framework-enabled MacOSX.
|
||
|
||
|
||
What's New in Python 2.2c1?
|
||
===========================
|
||
|
||
*Release date: 14-Dec-2001*
|
||
|
||
Type/class unification and new-style classes
|
||
--------------------------------------------
|
||
|
||
- Guido's tutorial introduction to the new type/class features has
|
||
been extensively updated. See
|
||
|
||
http://www.python.org/2.2/descrintro.html
|
||
|
||
That remains the primary documentation in this area.
|
||
|
||
- Fixed a leak: instance variables declared with __slots__ were never
|
||
deleted!
|
||
|
||
- The "delete attribute" method of descriptor objects is called
|
||
__delete__, not __del__. In previous releases, it was mistakenly
|
||
called __del__, which created an unfortunate overloading condition
|
||
with finalizers. (The "get attribute" and "set attribute" methods
|
||
are still called __get__ and __set__, respectively.)
|
||
|
||
- Some subtle issues with the super built-in were fixed:
|
||
|
||
(a) When super itself is subclassed, its __get__ method would still
|
||
return an instance of the base class (i.e., of super).
|
||
|
||
(b) super(C, C()).__class__ would return C rather than super. This
|
||
is confusing. To fix this, I decided to change the semantics of
|
||
super so that it only applies to code attributes, not to data
|
||
attributes. After all, overriding data attributes is not
|
||
supported anyway.
|
||
|
||
(c) The __get__ method didn't check whether the argument was an
|
||
instance of the type used in creation of the super instance.
|
||
|
||
- Previously, hash() of an instance of a subclass of a mutable type
|
||
(list or dictionary) would return some value, rather than raising
|
||
TypeError. This has been fixed. Also, directly calling
|
||
dict.__hash__ and list.__hash__ now raises the same TypeError
|
||
(previously, these were the same as object.__hash__).
|
||
|
||
- New-style objects now support deleting their __dict__. This is for
|
||
all intents and purposes equivalent to assigning a brand new empty
|
||
dictionary, but saves space if the object is not used further.
|
||
|
||
Core and builtins
|
||
-----------------
|
||
|
||
- -Qnew now works as documented in PEP 238: when -Qnew is passed on
|
||
the command line, all occurrences of "/" use true division instead
|
||
of classic division. See the PEP for details. Note that "all"
|
||
means all instances in library and 3rd-party modules, as well as in
|
||
your own code. As the PEP says, -Qnew is intended for use only in
|
||
educational environments with control over the libraries in use.
|
||
Note that test_coercion.py in the standard Python test suite fails
|
||
under -Qnew; this is expected, and won't be repaired until true
|
||
division becomes the default (in the meantime, test_coercion is
|
||
testing the current rules).
|
||
|
||
- complex() now only allows the first argument to be a string
|
||
argument, and raises TypeError if either the second arg is a string
|
||
or if the second arg is specified when the first is a string.
|
||
|
||
Extension modules
|
||
-----------------
|
||
|
||
- gc.get_referents was renamed to gc.get_referrers.
|
||
|
||
Library
|
||
-------
|
||
|
||
- Functions in the os.spawn() family now release the global interpreter
|
||
lock around calling the platform spawn. They should always have done
|
||
this, but did not before 2.2c1. Multithreaded programs calling
|
||
an os.spawn function with P_WAIT will no longer block all Python threads
|
||
until the spawned program completes. It's possible that some programs
|
||
relies on blocking, although more likely by accident than by design.
|
||
|
||
- webbrowser defaults to netscape.exe on OS/2 now.
|
||
|
||
- Tix.ResizeHandle exposes detach_widget, hide, and show.
|
||
|
||
- The charset alias windows_1252 has been added.
|
||
|
||
- types.StringTypes is a tuple containing the defined string types;
|
||
usually this will be (str, unicode), but if Python was compiled
|
||
without Unicode support it will be just (str,).
|
||
|
||
- The pulldom and minidom modules were synchronized to PyXML.
|
||
|
||
Tools/Demos
|
||
-----------
|
||
|
||
- A new script called Tools/scripts/google.py was added, which fires
|
||
off a search on Google.
|
||
|
||
Build
|
||
-----
|
||
|
||
- Note that release builds of Python should arrange to define the
|
||
preprocessor symbol NDEBUG on the command line (or equivalent).
|
||
In the 2.2 pre-release series we tried to define this by magic in
|
||
Python.h instead, but it proved to cause problems for extension
|
||
authors. The Unix, Windows and Mac builds now all define NDEBUG in
|
||
release builds via cmdline (or equivalent) instead. Ports to
|
||
other platforms should do likewise.
|
||
|
||
- It is no longer necessary to use --with-suffix when building on a
|
||
case-insensitive file system (such as Mac OS X HFS+). In the build
|
||
directory an extension is used, but not in the installed python.
|
||
|
||
C API
|
||
-----
|
||
|
||
- New function PyDict_MergeFromSeq2() exposes the builtin dict
|
||
constructor's logic for updating a dictionary from an iterable object
|
||
producing key-value pairs.
|
||
|
||
- PyArg_ParseTupleAndKeywords() requires that the number of entries in
|
||
the keyword list equal the number of argument specifiers. This
|
||
wasn't checked correctly, and PyArg_ParseTupleAndKeywords could even
|
||
dump core in some bad cases. This has been repaired. As a result,
|
||
PyArg_ParseTupleAndKeywords may raise RuntimeError in bad cases that
|
||
previously went unchallenged.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
Tests
|
||
-----
|
||
|
||
Windows
|
||
-------
|
||
|
||
Mac
|
||
----
|
||
|
||
- In unix-Python on Mac OS X (and darwin) sys.platform is now "darwin",
|
||
without any trailing digits.
|
||
|
||
- Changed logic for finding python home in Mac OS X framework Pythons.
|
||
Now sys.executable points to the executable again, in stead of to
|
||
the shared library. The latter is used only for locating the python
|
||
home.
|
||
|
||
|
||
What's New in Python 2.2b2?
|
||
===========================
|
||
|
||
*Release date: 16-Nov-2001*
|
||
|
||
Type/class unification and new-style classes
|
||
--------------------------------------------
|
||
|
||
- Multiple inheritance mixing new-style and classic classes in the
|
||
list of base classes is now allowed, so this works now:
|
||
|
||
class Classic: pass
|
||
class Mixed(Classic, object): pass
|
||
|
||
The MRO (method resolution order) for each base class is respected
|
||
according to its kind, but the MRO for the derived class is computed
|
||
using new-style MRO rules if any base class is a new-style class.
|
||
This needs to be documented.
|
||
|
||
- The new builtin dictionary() constructor, and dictionary type, have
|
||
been renamed to dict. This reflects a decade of common usage.
|
||
|
||
- dict() now accepts an iterable object producing 2-sequences. For
|
||
example, dict(d.items()) == d for any dictionary d. The argument,
|
||
and the elements of the argument, can be any iterable objects.
|
||
|
||
- New-style classes can now have a __del__ method, which is called
|
||
when the instance is deleted (just like for classic classes).
|
||
|
||
- Assignment to object.__dict__ is now possible, for objects that are
|
||
instances of new-style classes that have a __dict__ (unless the base
|
||
class forbids it).
|
||
|
||
- Methods of built-in types now properly check for keyword arguments
|
||
(formerly these were silently ignored). The only built-in methods
|
||
that take keyword arguments are __call__, __init__ and __new__.
|
||
|
||
- The socket function has been converted to a type; see below.
|
||
|
||
Core and builtins
|
||
-----------------
|
||
|
||
- Assignment to __debug__ raises SyntaxError at compile-time. This
|
||
was promised when 2.1c1 was released as "What's New in Python 2.1c1"
|
||
(see below) says.
|
||
|
||
- Clarified the error messages for unsupported operands to an operator
|
||
(like 1 + '').
|
||
|
||
Extension modules
|
||
-----------------
|
||
|
||
- mmap has a new keyword argument, "access", allowing a uniform way for
|
||
both Windows and Unix users to create read-only, write-through and
|
||
copy-on-write memory mappings. This was previously possible only on
|
||
Unix. A new keyword argument was required to support this in a
|
||
uniform way because the mmap() signatures had diverged across
|
||
platforms. Thanks to Jay T Miller for repairing this!
|
||
|
||
- By default, the gc.garbage list now contains only those instances in
|
||
unreachable cycles that have __del__ methods; in 2.1 it contained all
|
||
instances in unreachable cycles. "Instances" here has been generalized
|
||
to include instances of both new-style and old-style classes.
|
||
|
||
- The socket module defines a new method for socket objects,
|
||
sendall(). This is like send() but may make multiple calls to
|
||
send() until all data has been sent. Also, the socket function has
|
||
been converted to a subclassable type, like list and tuple (etc.)
|
||
before it; socket and SocketType are now the same thing.
|
||
|
||
- Various bugfixes to the curses module. There is now a test suite
|
||
for the curses module (you have to run it manually).
|
||
|
||
- binascii.b2a_base64 no longer places an arbitrary restriction of 57
|
||
bytes on its input.
|
||
|
||
Library
|
||
-------
|
||
|
||
- tkFileDialog exposes a Directory class and askdirectory
|
||
convenience function.
|
||
|
||
- Symbolic group names in regular expressions must be unique. For
|
||
example, the regexp r'(?P<abc>)(?P<abc>)' is not allowed, because a
|
||
single name can't mean both "group 1" and "group 2" simultaneously.
|
||
Python 2.2 detects this error at regexp compilation time;
|
||
previously, the error went undetected, and results were
|
||
unpredictable. Also in sre, the pattern.split(), pattern.sub(), and
|
||
pattern.subn() methods have been rewritten in C. Also, an
|
||
experimental function/method finditer() has been added, which works
|
||
like findall() but returns an iterator.
|
||
|
||
- Tix exposes more commands through the classes DirSelectBox,
|
||
DirSelectDialog, ListNoteBook, Meter, CheckList, and the
|
||
methods tix_addbitmapdir, tix_cget, tix_configure, tix_filedialog,
|
||
tix_getbitmap, tix_getimage, tix_option_get, and tix_resetoptions.
|
||
|
||
- Traceback objects are now scanned by cyclic garbage collection, so
|
||
cycles created by casual use of sys.exc_info() no longer cause
|
||
permanent memory leaks (provided garbage collection is enabled).
|
||
|
||
- os.extsep -- a new variable needed by the RISCOS support. It is the
|
||
separator used by extensions, and is '.' on all platforms except
|
||
RISCOS, where it is '/'. There is no need to use this variable
|
||
unless you have a masochistic desire to port your code to RISCOS.
|
||
|
||
- mimetypes.py has optional support for non-standard, but commonly
|
||
found types. guess_type() and guess_extension() now accept an
|
||
optional 'strict' flag, defaulting to true, which controls whether
|
||
recognize non-standard types or not. A few non-standard types we
|
||
know about have been added. Also, when run as a script, there are
|
||
new -l and -e options.
|
||
|
||
- statcache is now deprecated.
|
||
|
||
- email.Utils.formatdate() now produces the preferred RFC 2822 style
|
||
dates with numeric timezones (it used to produce obsolete dates
|
||
hard coded to "GMT" timezone). An optional 'localtime' flag is
|
||
added to produce dates in the local timezone, with daylight savings
|
||
time properly taken into account.
|
||
|
||
- In pickle and cPickle, instead of masking errors in load() by
|
||
transforming them into SystemError, we let the original exception
|
||
propagate out. Also, implement support for __safe_for_unpickling__
|
||
in pickle, as it already was supported in cPickle.
|
||
|
||
Tools/Demos
|
||
-----------
|
||
|
||
Build
|
||
-----
|
||
|
||
- The dbm module is built using libdb1 if available. The bsddb module
|
||
is built with libdb3 if available.
|
||
|
||
- Misc/Makefile.pre.in has been removed by BDFL pronouncement.
|
||
|
||
C API
|
||
-----
|
||
|
||
- New function PySequence_Fast_GET_SIZE() returns the size of a non-
|
||
NULL result from PySequence_Fast(), more quickly than calling
|
||
PySequence_Size().
|
||
|
||
- New argument unpacking function PyArg_UnpackTuple() added.
|
||
|
||
- New functions PyObject_CallFunctionObjArgs() and
|
||
PyObject_CallMethodObjArgs() have been added to make it more
|
||
convenient and efficient to call functions and methods from C.
|
||
|
||
- PyArg_ParseTupleAndKeywords() no longer masks errors, so it's
|
||
possible that this will propagate errors it didn't before.
|
||
|
||
- New function PyObject_CheckReadBuffer(), which returns true if its
|
||
argument supports the single-segment readable buffer interface.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
- We've finally confirmed that this release builds on HP-UX 11.00,
|
||
*with* threads, and passes the test suite.
|
||
|
||
- Thanks to a series of patches from Michael Muller, Python may build
|
||
again under OS/2 Visual Age C++.
|
||
|
||
- Updated RISCOS port by Dietmar Schwertberger.
|
||
|
||
Tests
|
||
-----
|
||
|
||
- Added a test script for the curses module. It isn't run automatically;
|
||
regrtest.py must be run with '-u curses' to enable it.
|
||
|
||
Windows
|
||
-------
|
||
|
||
Mac
|
||
----
|
||
|
||
- PythonScript has been moved to unsupported and is slated to be
|
||
removed completely in the next release.
|
||
|
||
- It should now be possible to build applets that work on both OS9 and
|
||
OSX.
|
||
|
||
- The core is now linked with CoreServices not Carbon; as a side
|
||
result, default 8bit encoding on OSX is now ASCII.
|
||
|
||
- Python should now build on OSX 10.1.1
|
||
|
||
|
||
What's New in Python 2.2b1?
|
||
===========================
|
||
|
||
*Release date: 19-Oct-2001*
|
||
|
||
Type/class unification and new-style classes
|
||
--------------------------------------------
|
||
|
||
- New-style classes are now always dynamic (except for built-in and
|
||
extension types). There is no longer a performance penalty, and I
|
||
no longer see another reason to keep this baggage around. One relic
|
||
remains: the __dict__ of a new-style class is a read-only proxy; you
|
||
must set the class's attribute to modify it. As a consequence, the
|
||
__defined__ attribute of new-style types no longer exists, for lack
|
||
of need: there is once again only one __dict__ (although in the
|
||
future a __cache__ may be resurrected with a similar function, if I
|
||
can prove that it actually speeds things up).
|
||
|
||
- C.__doc__ now works as expected for new-style classes (in 2.2a4 it
|
||
always returned None, even when there was a class docstring).
|
||
|
||
- doctest now finds and runs docstrings attached to new-style classes,
|
||
class methods, static methods, and properties.
|
||
|
||
Core and builtins
|
||
-----------------
|
||
|
||
- A very subtle syntactical pitfall in list comprehensions was fixed.
|
||
For example: [a+b for a in 'abc', for b in 'def']. The comma in
|
||
this example is a mistake. Previously, this would silently let 'a'
|
||
iterate over the singleton tuple ('abc',), yielding ['abcd', 'abce',
|
||
'abcf'] rather than the intended ['ad', 'ae', 'af', 'bd', 'be',
|
||
'bf', 'cd', 'ce', 'cf']. Now, this is flagged as a syntax error.
|
||
Note that [a for a in <singleton>] is a convoluted way to say
|
||
[<singleton>] anyway, so it's not like any expressiveness is lost.
|
||
|
||
- getattr(obj, name, default) now only catches AttributeError, as
|
||
documented, rather than returning the default value for all
|
||
exceptions (which could mask bugs in a __getattr__ hook, for
|
||
example).
|
||
|
||
- Weak reference objects are now part of the core and offer a C API.
|
||
A bug which could allow a core dump when binary operations involved
|
||
proxy reference has been fixed. weakref.ReferenceError is now a
|
||
built-in exception.
|
||
|
||
- unicode(obj) now behaves more like str(obj), accepting arbitrary
|
||
objects, and calling a __unicode__ method if it exists.
|
||
unicode(obj, encoding) and unicode(obj, encoding, errors) still
|
||
require an 8-bit string or character buffer argument.
|
||
|
||
- isinstance() now allows any object as the first argument and a
|
||
class, a type or something with a __bases__ tuple attribute for the
|
||
second argument. The second argument may also be a tuple of a
|
||
class, type, or something with __bases__, in which case isinstance()
|
||
will return true if the first argument is an instance of any of the
|
||
things contained in the second argument tuple. E.g.
|
||
|
||
isinstance(x, (A, B))
|
||
|
||
returns true if x is an instance of A or B.
|
||
|
||
Extension modules
|
||
-----------------
|
||
|
||
- thread.start_new_thread() now returns the thread ID (previously None).
|
||
|
||
- binascii has now two quopri support functions, a2b_qp and b2a_qp.
|
||
|
||
- readline now supports setting the startup_hook and the
|
||
pre_event_hook, and adds the add_history() function.
|
||
|
||
- os and posix supports chroot(), setgroups() and unsetenv() where
|
||
available. The stat(), fstat(), statvfs() and fstatvfs() functions
|
||
now return "pseudo-sequences" -- the various fields can now be
|
||
accessed as attributes (e.g. os.stat("/").st_mtime) but for
|
||
backwards compatibility they also behave as a fixed-length sequence.
|
||
Some platform-specific fields (e.g. st_rdev) are only accessible as
|
||
attributes.
|
||
|
||
- time: localtime(), gmtime() and strptime() now return a
|
||
pseudo-sequence similar to the os.stat() return value, with
|
||
attributes like tm_year etc.
|
||
|
||
- Decompression objects in the zlib module now accept an optional
|
||
second parameter to decompress() that specifies the maximum amount
|
||
of memory to use for the uncompressed data.
|
||
|
||
- optional SSL support in the socket module now exports OpenSSL
|
||
functions RAND_add(), RAND_egd(), and RAND_status(). These calls
|
||
are useful on platforms like Solaris where OpenSSL does not
|
||
automatically seed its PRNG. Also, the keyfile and certfile
|
||
arguments to socket.ssl() are now optional.
|
||
|
||
- posixmodule (and by extension, the os module on POSIX platforms) now
|
||
exports O_LARGEFILE, O_DIRECT, O_DIRECTORY, and O_NOFOLLOW.
|
||
|
||
Library
|
||
-------
|
||
|
||
- doctest now excludes functions and classes not defined by the module
|
||
being tested, thanks to Tim Hochberg.
|
||
|
||
- HotShot, a new profiler implemented using a C-based callback, has
|
||
been added. This substantially reduces the overhead of profiling,
|
||
but it is still quite preliminary. Support modules and
|
||
documentation will be added in upcoming releases (before 2.2 final).
|
||
|
||
- profile now produces correct output in situations where an exception
|
||
raised in Python is cleared by C code (e.g. hasattr()). This used
|
||
to cause wrong output, including spurious claims of recursive
|
||
functions and attribution of time spent to the wrong function.
|
||
|
||
The code and documentation for the derived OldProfile and HotProfile
|
||
profiling classes was removed. The code hasn't worked for years (if
|
||
you tried to use them, they raised exceptions). OldProfile
|
||
intended to reproduce the behavior of the profiler Python used more
|
||
than 7 years ago, and isn't interesting anymore. HotProfile intended
|
||
to provide a faster profiler (but producing less information), and
|
||
that's a worthy goal we intend to meet via a different approach (but
|
||
without losing information).
|
||
|
||
- Profile.calibrate() has a new implementation that should deliver
|
||
a much better system-specific calibration constant. The constant can
|
||
now be specified in an instance constructor, or as a Profile class or
|
||
instance variable, instead of by editing profile.py's source code.
|
||
Calibration must still be done manually (see the docs for the profile
|
||
module).
|
||
|
||
Note that Profile.calibrate() must be overriden by subclasses.
|
||
Improving the accuracy required exploiting detailed knowledge of
|
||
profiler internals; the earlier method abstracted away the details
|
||
and measured a simplified model instead, but consequently computed
|
||
a constant too small by a factor of 2 on some modern machines.
|
||
|
||
- quopri's encode and decode methods take an optional header parameter,
|
||
which indicates whether output is intended for the header 'Q'
|
||
encoding.
|
||
|
||
- The SocketServer.ThreadingMixIn class now closes the request after
|
||
finish_request() returns. (Not when it errors out though.)
|
||
|
||
- The nntplib module's NNTP.body() method has grown a 'file' argument
|
||
to allow saving the message body to a file.
|
||
|
||
- The email package has added a class email.Parser.HeaderParser which
|
||
only parses headers and does not recurse into the message's body.
|
||
Also, the module/class MIMEAudio has been added for representing
|
||
audio data (contributed by Anthony Baxter).
|
||
|
||
- ftplib should be able to handle files > 2GB.
|
||
|
||
- ConfigParser.getboolean() now also interprets TRUE, FALSE, YES, NO,
|
||
ON, and OFF.
|
||
|
||
- xml.dom.minidom NodeList objects now support the length attribute
|
||
and item() method as required by the DOM specifications.
|
||
|
||
Tools/Demos
|
||
-----------
|
||
|
||
- Demo/dns was removed. It no longer serves any purpose; a package
|
||
derived from it is now maintained by Anthony Baxter, see
|
||
http://PyDNS.SourceForge.net.
|
||
|
||
- The freeze tool has been made more robust, and two new options have
|
||
been added: -X and -E.
|
||
|
||
Build
|
||
-----
|
||
|
||
- configure will use CXX in LINKCC if CXX is used to build main() and
|
||
the system requires to link a C++ main using the C++ compiler.
|
||
|
||
C API
|
||
-----
|
||
|
||
- The documentation for the tp_compare slot is updated to require that
|
||
the return value must be -1, 0, 1; an arbitrary number <0 or >0 is
|
||
not correct. This is not yet enforced but will be enforced in
|
||
Python 2.3; even later, we may use -2 to indicate errors and +2 for
|
||
"NotImplemented". Right now, -1 should be used for an error return.
|
||
|
||
- PyLong_AsLongLong() now accepts int (as well as long) arguments.
|
||
Consequently, PyArg_ParseTuple's 'L' code also accepts int (as well
|
||
as long) arguments.
|
||
|
||
- PyThread_start_new_thread() now returns a long int giving the thread
|
||
ID, if one can be calculated; it returns -1 for error, 0 if no
|
||
thread ID is calculated (this is an incompatible change, but only
|
||
the thread module used this API). This code has only really been
|
||
tested on Linux and Windows; other platforms please beware (and
|
||
report any bugs or strange behavior).
|
||
|
||
- PyUnicode_FromEncodedObject() no longer accepts Unicode objects as
|
||
input.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
Tests
|
||
-----
|
||
|
||
Windows
|
||
-------
|
||
|
||
- Installer: If you install IDLE, and don't disable file-extension
|
||
registration, a new "Edit with IDLE" context (right-click) menu entry
|
||
is created for .py and .pyw files.
|
||
|
||
- The signal module now supports SIGBREAK on Windows, thanks to Steven
|
||
Scott. Note that SIGBREAK is unique to Windows. The default SIGBREAK
|
||
action remains to call Win32 ExitProcess(). This can be changed via
|
||
signal.signal(). For example::
|
||
|
||
# Make Ctrl+Break raise KeyboardInterrupt, like Python's default Ctrl+C
|
||
# (SIGINT) behavior.
|
||
import signal
|
||
signal.signal(signal.SIGBREAK, signal.default_int_handler)
|
||
|
||
try:
|
||
while 1:
|
||
pass
|
||
except KeyboardInterrupt:
|
||
# We get here on Ctrl+C or Ctrl+Break now; if we had not changed
|
||
# SIGBREAK, only on Ctrl+C (and Ctrl+Break would terminate the
|
||
# program without the possibility for any Python-level cleanup).
|
||
print "Clean exit"
|
||
|
||
|
||
What's New in Python 2.2a4?
|
||
===========================
|
||
|
||
*Release date: 28-Sep-2001*
|
||
|
||
Type/class unification and new-style classes
|
||
--------------------------------------------
|
||
|
||
- pydoc and inspect are now aware of new-style classes;
|
||
e.g. help(list) at the interactive prompt now shows proper
|
||
documentation for all operations on list objects.
|
||
|
||
- Applications using Jim Fulton's ExtensionClass module can now safely
|
||
be used with Python 2.2. In particular, Zope 2.4.1 now works with
|
||
Python 2.2 (as well as with Python 2.1.1). The Demo/metaclass
|
||
examples also work again. It is hoped that Gtk and Boost also work
|
||
with 2.2a4 and beyond. (If you can confirm this, please write
|
||
webmaster@python.org; if there are still problems, please open a bug
|
||
report on SourceForge.)
|
||
|
||
- property() now takes 4 keyword arguments: fget, fset, fdel and doc.
|
||
These map to read-only attributes 'fget', 'fset', 'fdel', and '__doc__'
|
||
in the constructed property object. fget, fset and fdel weren't
|
||
discoverable from Python in 2.2a3. __doc__ is new, and allows to
|
||
associate a docstring with a property.
|
||
|
||
- Comparison overloading is now more completely implemented. For
|
||
example, a str subclass instance can properly be compared to a str
|
||
instance, and it can properly overload comparison. Ditto for most
|
||
other built-in object types.
|
||
|
||
- The repr() of new-style classes has changed; instead of <type
|
||
'M.Foo'> a new-style class is now rendered as <class 'M.Foo'>,
|
||
*except* for built-in types, which are still rendered as <type
|
||
'Foo'> (to avoid upsetting existing code that might parse or
|
||
otherwise rely on repr() of certain type objects).
|
||
|
||
- The repr() of new-style objects is now always <Foo object at XXX>;
|
||
previously, it was sometimes <Foo instance at XXX>.
|
||
|
||
- For new-style classes, what was previously called __getattr__ is now
|
||
called __getattribute__. This method, if defined, is called for
|
||
*every* attribute access. A new __getattr__ hook more similar to the
|
||
one in classic classes is defined which is called only if regular
|
||
attribute access raises AttributeError; to catch *all* attribute
|
||
access, you can use __getattribute__ (for new-style classes). If
|
||
both are defined, __getattribute__ is called first, and if it raises
|
||
AttributeError, __getattr__ is called.
|
||
|
||
- The __class__ attribute of new-style objects can be assigned to.
|
||
The new class must have the same C-level object layout as the old
|
||
class.
|
||
|
||
- The builtin file type can be subclassed now. In the usual pattern,
|
||
"file" is the name of the builtin type, and file() is a new builtin
|
||
constructor, with the same signature as the builtin open() function.
|
||
file() is now the preferred way to open a file.
|
||
|
||
- Previously, __new__ would only see sequential arguments passed to
|
||
the type in a constructor call; __init__ would see both sequential
|
||
and keyword arguments. This made no sense whatsoever any more, so
|
||
now both __new__ and __init__ see all arguments.
|
||
|
||
- Previously, hash() applied to an instance of a subclass of str or
|
||
unicode always returned 0. This has been repaired.
|
||
|
||
- Previously, an operation on an instance of a subclass of an
|
||
immutable type (int, long, float, complex, tuple, str, unicode),
|
||
where the subtype didn't override the operation (and so the
|
||
operation was handled by the builtin type), could return that
|
||
instance instead a value of the base type. For example, if s was of
|
||
a str subclass type, s[:] returned s as-is. Now it returns a str
|
||
with the same value as s.
|
||
|
||
- Provisional support for pickling new-style objects has been added.
|
||
|
||
Core
|
||
----
|
||
|
||
- file.writelines() now accepts any iterable object producing strings.
|
||
|
||
- PyUnicode_FromEncodedObject() now works very much like
|
||
PyObject_Str(obj) in that it tries to use __str__/tp_str
|
||
on the object if the object is not a string or buffer. This
|
||
makes unicode() behave like str() when applied to non-string/buffer
|
||
objects.
|
||
|
||
- PyFile_WriteObject now passes Unicode objects to the file's write
|
||
method. As a result, all file-like objects which may be the target
|
||
of a print statement must support Unicode objects, i.e. they must
|
||
at least convert them into ASCII strings.
|
||
|
||
- Thread scheduling on Solaris should be improved; it is no longer
|
||
necessary to insert a small sleep at the start of a thread in order
|
||
to let other runnable threads be scheduled.
|
||
|
||
Library
|
||
-------
|
||
|
||
- StringIO.StringIO instances and cStringIO.StringIO instances support
|
||
read character buffer compatible objects for their .write() methods.
|
||
These objects are converted to strings and then handled as such
|
||
by the instances.
|
||
|
||
- The "email" package has been added. This is basically a port of the
|
||
mimelib package <http://sf.net/projects/mimelib> with API changes
|
||
and some implementations updated to use iterators and generators.
|
||
|
||
- difflib.ndiff() and difflib.Differ.compare() are generators now. This
|
||
restores the ability of Tools/scripts/ndiff.py to start producing output
|
||
before the entire comparison is complete.
|
||
|
||
- StringIO.StringIO instances and cStringIO.StringIO instances support
|
||
iteration just like file objects (i.e. their .readline() method is
|
||
called for each iteration until it returns an empty string).
|
||
|
||
- The codecs module has grown four new helper APIs to access
|
||
builtin codecs: getencoder(), getdecoder(), getreader(),
|
||
getwriter().
|
||
|
||
- SimpleXMLRPCServer: a new module (based upon SimpleHTMLServer)
|
||
simplifies writing XML RPC servers.
|
||
|
||
- os.path.realpath(): a new function that returns the absolute pathname
|
||
after interpretation of symbolic links. On non-Unix systems, this
|
||
is an alias for os.path.abspath().
|
||
|
||
- operator.indexOf() (PySequence_Index() in the C API) now works with any
|
||
iterable object.
|
||
|
||
- smtplib now supports various authentication and security features of
|
||
the SMTP protocol through the new login() and starttls() methods.
|
||
|
||
- hmac: a new module implementing keyed hashing for message
|
||
authentication.
|
||
|
||
- mimetypes now recognizes more extensions and file types. At the
|
||
same time, some mappings not sanctioned by IANA were removed.
|
||
|
||
- The "compiler" package has been brought up to date to the state of
|
||
Python 2.2 bytecode generation. It has also been promoted from a
|
||
Tool to a standard library package. (Tools/compiler still exists as
|
||
a sample driver.)
|
||
|
||
Tools
|
||
-----
|
||
|
||
Build
|
||
-----
|
||
|
||
- Large file support (LFS) is now automatic when the platform supports
|
||
it; no more manual configuration tweaks are needed. On Linux, at
|
||
least, it's possible to have a system whose C library supports large
|
||
files but whose kernel doesn't; in this case, large file support is
|
||
still enabled but doesn't do you any good unless you upgrade your
|
||
kernel or share your Python executable with another system whose
|
||
kernel has large file support.
|
||
|
||
- The configure script now supplies plausible defaults in a
|
||
cross-compilation environment. This doesn't mean that the supplied
|
||
values are always correct, or that cross-compilation now works
|
||
flawlessly -- but it's a first step (and it shuts up most of
|
||
autoconf's warnings about AC_TRY_RUN).
|
||
|
||
- The Unix build is now a bit less chatty, courtesy of the parser
|
||
generator. The build is completely silent (except for errors) when
|
||
using "make -s", thanks to a -q option to setup.py.
|
||
|
||
C API
|
||
-----
|
||
|
||
- The "structmember" API now supports some new flag bits to deny read
|
||
and/or write access to attributes in restricted execution mode.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
- Compaq's iPAQ handheld, running the "familiar" Linux distribution
|
||
(http://familiar.handhelds.org).
|
||
|
||
Tests
|
||
-----
|
||
|
||
- The "classic" standard tests, which work by comparing stdout to
|
||
an expected-output file under Lib/test/output/, no longer stop at
|
||
the first mismatch. Instead the test is run to completion, and a
|
||
variant of ndiff-style comparison is used to report all differences.
|
||
This is much easier to understand than the previous style of reporting.
|
||
|
||
- The unittest-based standard tests now use regrtest's test_main()
|
||
convention, instead of running as a side-effect of merely being
|
||
imported. This allows these tests to be run in more natural and
|
||
flexible ways as unittests, outside the regrtest framework.
|
||
|
||
- regrtest.py is much better integrated with unittest and doctest now,
|
||
especially in regard to reporting errors.
|
||
|
||
Windows
|
||
-------
|
||
|
||
- Large file support now also works for files > 4GB, on filesystems
|
||
that support it (NTFS under Windows 2000). See "What's New in
|
||
Python 2.2a3" for more detail.
|
||
|
||
|
||
What's New in Python 2.2a3?
|
||
===========================
|
||
|
||
*Release Date: 07-Sep-2001*
|
||
|
||
Core
|
||
----
|
||
|
||
- Conversion of long to float now raises OverflowError if the long is too
|
||
big to represent as a C double.
|
||
|
||
- The 3-argument builtin pow() no longer allows a third non-None argument
|
||
if either of the first two arguments is a float, or if both are of
|
||
integer types and the second argument is negative (in which latter case
|
||
the arguments are converted to float, so this is really the same
|
||
restriction).
|
||
|
||
- The builtin dir() now returns more information, and sometimes much
|
||
more, generally naming all attributes of an object, and all attributes
|
||
reachable from the object via its class, and from its class's base
|
||
classes, and so on from them too. Example: in 2.2a2, dir([]) returned
|
||
an empty list. In 2.2a3,
|
||
|
||
>>> dir([])
|
||
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__',
|
||
'__eq__', '__ge__', '__getattr__', '__getitem__', '__getslice__',
|
||
'__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__le__',
|
||
'__len__', '__lt__', '__mul__', '__ne__', '__new__', '__repr__',
|
||
'__rmul__', '__setattr__', '__setitem__', '__setslice__', '__str__',
|
||
'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove',
|
||
'reverse', 'sort']
|
||
|
||
dir(module) continues to return only the module's attributes, though.
|
||
|
||
- Overflowing operations on plain ints now return a long int rather
|
||
than raising OverflowError. This is a partial implementation of PEP
|
||
237. You can use -Wdefault::OverflowWarning to enable a warning for
|
||
this situation, and -Werror::OverflowWarning to revert to the old
|
||
OverflowError exception.
|
||
|
||
- A new command line option, -Q<arg>, is added to control run-time
|
||
warnings for the use of classic division. (See PEP 238.) Possible
|
||
values are -Qold, -Qwarn, -Qwarnall, and -Qnew. The default is
|
||
-Qold, meaning the / operator has its classic meaning and no
|
||
warnings are issued. Using -Qwarn issues a run-time warning about
|
||
all uses of classic division for int and long arguments; -Qwarnall
|
||
also warns about classic division for float and complex arguments
|
||
(for use with fixdiv.py).
|
||
[Note: the remainder of this item (preserved below) became
|
||
obsolete in 2.2c1 -- -Qnew has global effect in 2.2] ::
|
||
|
||
Using -Qnew is questionable; it turns on new division by default, but
|
||
only in the __main__ module. You can usefully combine -Qwarn or
|
||
-Qwarnall and -Qnew: this gives the __main__ module new division, and
|
||
warns about classic division everywhere else.
|
||
|
||
- Many built-in types can now be subclassed. This applies to int,
|
||
long, float, str, unicode, and tuple. (The types complex, list and
|
||
dictionary can also be subclassed; this was introduced earlier.)
|
||
Note that restrictions apply when subclassing immutable built-in
|
||
types: you can only affect the value of the instance by overloading
|
||
__new__. You can add mutable attributes, and the subclass instances
|
||
will have a __dict__ attribute, but you cannot change the "value"
|
||
(as implemented by the base class) of an immutable subclass instance
|
||
once it is created.
|
||
|
||
- The dictionary constructor now takes an optional argument, a
|
||
mapping-like object, and initializes the dictionary from its
|
||
(key, value) pairs.
|
||
|
||
- A new built-in type, super, has been added. This facilitates making
|
||
"cooperative super calls" in a multiple inheritance setting. For an
|
||
explanation, see http://www.python.org/2.2/descrintro.html#cooperation
|
||
|
||
- A new built-in type, property, has been added. This enables the
|
||
creation of "properties". These are attributes implemented by
|
||
getter and setter functions (or only one of these for read-only or
|
||
write-only attributes), without the need to override __getattr__.
|
||
See http://www.python.org/2.2/descrintro.html#property
|
||
|
||
- The syntax of floating-point and imaginary literals has been
|
||
liberalized, to allow leading zeroes. Examples of literals now
|
||
legal that were SyntaxErrors before:
|
||
|
||
00.0 0e3 0100j 07.5 00000000000000000008.
|
||
|
||
- An old tokenizer bug allowed floating point literals with an incomplete
|
||
exponent, such as 1e and 3.1e-. Such literals now raise SyntaxError.
|
||
|
||
Library
|
||
-------
|
||
|
||
- telnetlib includes symbolic names for the options, and support for
|
||
setting an option negotiation callback.
|
||
|
||
- The new C standard no longer requires that math libraries set errno to
|
||
ERANGE on overflow. For platform libraries that exploit this new
|
||
freedom, Python's overflow-checking was wholly broken. A new overflow-
|
||
checking scheme attempts to repair that, but may not be reliable on all
|
||
platforms (C doesn't seem to provide anything both useful and portable
|
||
in this area anymore).
|
||
|
||
- Asynchronous timeout actions are available through the new class
|
||
threading.Timer.
|
||
|
||
- math.log and math.log10 now return sensible results for even huge
|
||
long arguments. For example, math.log10(10 ** 10000) ~= 10000.0.
|
||
|
||
- A new function, imp.lock_held(), returns 1 when the import lock is
|
||
currently held. See the docs for the imp module.
|
||
|
||
- pickle, cPickle and marshal on 32-bit platforms can now correctly read
|
||
dumps containing ints written on platforms where Python ints are 8 bytes.
|
||
When read on a box where Python ints are 4 bytes, such values are
|
||
converted to Python longs.
|
||
|
||
- In restricted execution mode (using the rexec module), unmarshalling
|
||
code objects is no longer allowed. This plugs a security hole.
|
||
|
||
- unittest.TestResult instances no longer store references to tracebacks
|
||
generated by test failures. This prevents unexpected dangling references
|
||
to objects that should be garbage collected between tests.
|
||
|
||
Tools
|
||
-----
|
||
|
||
- Tools/scripts/fixdiv.py has been added which can be used to fix
|
||
division operators as per PEP 238.
|
||
|
||
Build
|
||
-----
|
||
|
||
- If you are an adventurous person using Mac OS X you may want to look at
|
||
Mac/OSX. There is a Makefile there that will build Python as a real Mac
|
||
application, which can be used for experimenting with Carbon or Cocoa.
|
||
Discussion of this on pythonmac-sig, please.
|
||
|
||
C API
|
||
-----
|
||
|
||
- New function PyObject_Dir(obj), like Python __builtin__.dir(obj).
|
||
|
||
- Note that PyLong_AsDouble can fail! This has always been true, but no
|
||
callers checked for it. It's more likely to fail now, because overflow
|
||
errors are properly detected now. The proper way to check::
|
||
|
||
double x = PyLong_AsDouble(some_long_object);
|
||
if (x == -1.0 && PyErr_Occurred()) {
|
||
/* The conversion failed. */
|
||
}
|
||
|
||
- The GC API has been changed. Extensions that use the old API will still
|
||
compile but will not participate in GC. To upgrade an extension
|
||
module:
|
||
|
||
- rename Py_TPFLAGS_GC to PyTPFLAGS_HAVE_GC
|
||
|
||
- use PyObject_GC_New or PyObject_GC_NewVar to allocate objects and
|
||
PyObject_GC_Del to deallocate them
|
||
|
||
- rename PyObject_GC_Init to PyObject_GC_Track and PyObject_GC_Fini
|
||
to PyObject_GC_UnTrack
|
||
|
||
- remove PyGC_HEAD_SIZE from object size calculations
|
||
|
||
- remove calls to PyObject_AS_GC and PyObject_FROM_GC
|
||
|
||
- Two new functions: PyString_FromFormat() and PyString_FromFormatV().
|
||
These can be used safely to construct string objects from a
|
||
sprintf-style format string (similar to the format string supported
|
||
by PyErr_Format()).
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
- Stephen Hansen contributed patches sufficient to get a clean compile
|
||
under Borland C (Windows), but he reports problems running it and ran
|
||
out of time to complete the port. Volunteers? Expect a MemoryError
|
||
when importing the types module; this is probably shallow, and
|
||
causing later failures too.
|
||
|
||
Tests
|
||
-----
|
||
|
||
Windows
|
||
-------
|
||
|
||
- Large file support is now enabled on Win32 platforms as well as on
|
||
Win64. This means that, for example, you can use f.tell() and f.seek()
|
||
to manipulate files larger than 2 gigabytes (provided you have enough
|
||
disk space, and are using a Windows filesystem that supports large
|
||
partitions). Windows filesystem limits: FAT has a 2GB (gigabyte)
|
||
filesize limit, and large file support makes no difference there.
|
||
FAT32's limit is 4GB, and files >= 2GB are easier to use from Python now.
|
||
NTFS has no practical limit on file size, and files of any size can be
|
||
used from Python now.
|
||
|
||
- The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
|
||
points to command.com (patch from Brian Quinlan).
|
||
|
||
|
||
What's New in Python 2.2a2?
|
||
===========================
|
||
|
||
*Release Date: 22-Aug-2001*
|
||
|
||
Build
|
||
-----
|
||
|
||
- Tim Peters developed a brand new Windows installer using Wise 8.1,
|
||
generously donated to us by Wise Solutions.
|
||
|
||
- configure supports a new option --enable-unicode, with the values
|
||
ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
|
||
type and supporting code is completely removed from the interpreter.
|
||
|
||
- A new configure option --enable-framework builds a Mac OS X framework,
|
||
which "make frameworkinstall" will install. This provides a starting
|
||
point for more mac-like functionality, join pythonmac-sig@python.org
|
||
if you are interested in helping.
|
||
|
||
- The NeXT platform is no longer supported.
|
||
|
||
- The 'new' module is now statically linked.
|
||
|
||
Tools
|
||
-----
|
||
|
||
- The new Tools/scripts/cleanfuture.py can be used to automatically
|
||
edit out obsolete future statements from Python source code. See
|
||
the module docstring for details.
|
||
|
||
Tests
|
||
-----
|
||
|
||
- regrtest.py now knows which tests are expected to be skipped on some
|
||
platforms, allowing to give clearer test result output. regrtest
|
||
also has optional --use/-u switch to run normally disabled tests
|
||
which require network access or consume significant disk resources.
|
||
|
||
- Several new tests in the standard test suite, with special thanks to
|
||
Nick Mathewson.
|
||
|
||
Core
|
||
----
|
||
|
||
- The floor division operator // has been added as outlined in PEP
|
||
238. The / operator still provides classic division (and will until
|
||
Python 3.0) unless "from __future__ import division" is included, in
|
||
which case the / operator will provide true division. The operator
|
||
module provides truediv() and floordiv() functions. Augmented
|
||
assignment variants are included, as are the equivalent overloadable
|
||
methods and C API methods. See the PEP for a full discussion:
|
||
<http://python.sf.net/peps/pep-0238.html>
|
||
|
||
- Future statements are now effective in simulated interactive shells
|
||
(like IDLE). This should "just work" by magic, but read Michael
|
||
Hudson's "Future statements in simulated shells" PEP 264 for full
|
||
details: <http://python.sf.net/peps/pep-0264.html>.
|
||
|
||
- The type/class unification (PEP 252-253) was integrated into the
|
||
trunk and is not so tentative any more (the exact specification of
|
||
some features is still tentative). A lot of work has done on fixing
|
||
bugs and adding robustness and features (performance still has to
|
||
come a long way).
|
||
|
||
- Warnings about a mismatch in the Python API during extension import
|
||
now use the Python warning framework (which makes it possible to
|
||
write filters for these warnings).
|
||
|
||
- A function's __dict__ (aka func_dict) will now always be a
|
||
dictionary. It used to be possible to delete it or set it to None,
|
||
but now both actions raise TypeErrors. It is still legal to set it
|
||
to a dictionary object. Getting func.__dict__ before any attributes
|
||
have been assigned now returns an empty dictionary instead of None.
|
||
|
||
- A new command line option, -E, was added which disables the use of
|
||
all environment variables, or at least those that are specifically
|
||
significant to Python. Usually those have a name starting with
|
||
"PYTHON". This was used to fix a problem where the tests fail if
|
||
the user happens to have PYTHONHOME or PYTHONPATH pointing to an
|
||
older distribution.
|
||
|
||
Library
|
||
-------
|
||
|
||
- New class Differ and new functions ndiff() and restore() in difflib.py.
|
||
These package the algorithms used by the popular Tools/scripts/ndiff.py,
|
||
for programmatic reuse.
|
||
|
||
- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
|
||
value using the minimal quoting required for the value; more
|
||
reliable than using xml.sax.saxutils.escape() for attribute values.
|
||
|
||
- Readline completion support for cmd.Cmd was added.
|
||
|
||
- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
|
||
|
||
- Added function threading.BoundedSemaphore()
|
||
|
||
- Added Ka-Ping Yee's cgitb.py module.
|
||
|
||
- The 'new' module now exposes the CO_xxx flags.
|
||
|
||
- The gc module offers the get_referents function.
|
||
|
||
New platforms
|
||
-------------
|
||
|
||
C API
|
||
-----
|
||
|
||
- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
|
||
which provide a cross-platform implementations for the
|
||
relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
|
||
the standard sprintf() and vsprintf() C lib APIs, these versions
|
||
apply bounds checking on the used buffer which enhances protection
|
||
against buffer overruns.
|
||
|
||
- Unicode APIs now use name mangling to assure that mixing interpreters
|
||
and extensions using different Unicode widths is rendered next to
|
||
impossible. Trying to import an incompatible Unicode-aware extension
|
||
will result in an ImportError. Unicode extensions writers must make
|
||
sure to check the Unicode width compatibility in their extensions by
|
||
using at least one of the mangled Unicode APIs in the extension.
|
||
|
||
- Two new flags METH_NOARGS and METH_O are available in method definition
|
||
tables to simplify implementation of methods with no arguments and a
|
||
single untyped argument. Calling such methods is more efficient than
|
||
calling corresponding METH_VARARGS methods. METH_OLDARGS is now
|
||
deprecated.
|
||
|
||
Windows
|
||
-------
|
||
|
||
- "import module" now compiles module.pyw if it exists and nothing else
|
||
relevant is found.
|
||
|
||
|
||
What's New in Python 2.2a1?
|
||
===========================
|
||
|
||
*Release date: 18-Jul-2001*
|
||
|
||
Core
|
||
----
|
||
|
||
- TENTATIVELY, a large amount of code implementing much of what's
|
||
described in PEP 252 (Making Types Look More Like Classes) and PEP
|
||
253 (Subtyping Built-in Types) was added. This will be released
|
||
with Python 2.2a1. Documentation will be provided separately
|
||
through http://www.python.org/2.2/. The purpose of releasing this
|
||
with Python 2.2a1 is to test backwards compatibility. It is
|
||
possible, though not likely, that a decision is made not to release
|
||
this code as part of 2.2 final, if any serious backwards
|
||
incompatibilities are found during alpha testing that cannot be
|
||
repaired.
|
||
|
||
- Generators were added; this is a new way to create an iterator (see
|
||
below) using what looks like a simple function containing one or
|
||
more 'yield' statements. See PEP 255. Since this adds a new
|
||
keyword to the language, this feature must be enabled by including a
|
||
future statement: "from __future__ import generators" (see PEP 236).
|
||
Generators will become a standard feature in a future release
|
||
(probably 2.3). Without this future statement, 'yield' remains an
|
||
ordinary identifier, but a warning is issued each time it is used.
|
||
(These warnings currently don't conform to the warnings framework of
|
||
PEP 230; we intend to fix this in 2.2a2.)
|
||
|
||
- The UTF-16 codec was modified to be more RFC compliant. It will now
|
||
only remove BOM characters at the start of the string and then
|
||
only if running in native mode (UTF-16-LE and -BE won't remove a
|
||
leading BMO character).
|
||
|
||
- Strings now have a new method .decode() to complement the already
|
||
existing .encode() method. These two methods provide direct access
|
||
to the corresponding decoders and encoders of the registered codecs.
|
||
|
||
To enhance the usability of the .encode() method, the special
|
||
casing of Unicode object return values was dropped (Unicode objects
|
||
were auto-magically converted to string using the default encoding).
|
||
|
||
Both methods will now return whatever the codec in charge of the
|
||
requested encoding returns as object, e.g. Unicode codecs will
|
||
return Unicode objects when decoding is requested ("<22><><EFBFBD>".decode("latin-1")
|
||
will return u"<22><><EFBFBD>"). This enables codec writer to create codecs
|
||
for various simple to use conversions.
|
||
|
||
New codecs were added to demonstrate these new features (the .encode()
|
||
and .decode() columns indicate the type of the returned objects):
|
||
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|Name | .encode() | .decode() | Description |
|
||
+=========+===========+===========+=============================+
|
||
|uu | string | string | UU codec (e.g. for email) |
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|base64 | string | string | base64 codec |
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|quopri | string | string | quoted-printable codec |
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|zlib | string | string | zlib compression |
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|hex | string | string | 2-byte hex codec |
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|rot-13 | string | Unicode | ROT-13 Unicode charmap codec|
|
||
+---------+-----------+-----------+-----------------------------+
|
||
|
||
- Some operating systems now support the concept of a default Unicode
|
||
encoding for file system operations. Notably, Windows supports 'mbcs'
|
||
as the default. The Macintosh will also adopt this concept in the medium
|
||
term, although the default encoding for that platform will be other than
|
||
'mbcs'.
|
||
|
||
On operating system that support non-ASCII filenames, it is common for
|
||
functions that return filenames (such as os.listdir()) to return Python
|
||
string objects pre-encoded using the default file system encoding for
|
||
the platform. As this encoding is likely to be different from Python's
|
||
default encoding, converting this name to a Unicode object before passing
|
||
it back to the Operating System would result in a Unicode error, as Python
|
||
would attempt to use its default encoding (generally ASCII) rather than
|
||
the default encoding for the file system.
|
||
|
||
In general, this change simply removes surprises when working with
|
||
Unicode and the file system, making these operations work as you expect,
|
||
increasing the transparency of Unicode objects in this context.
|
||
See [????] for more details, including examples.
|
||
|
||
- Float (and complex) literals in source code were evaluated to full
|
||
precision only when running from a .py file; the same code loaded from a
|
||
.pyc (or .pyo) file could suffer numeric differences starting at about the
|
||
12th significant decimal digit. For example, on a machine with IEEE-754
|
||
floating arithmetic,
|
||
|
||
x = 9007199254740992.0
|
||
print long(x)
|
||
|
||
printed 9007199254740992 if run directly from .py, but 9007199254740000
|
||
if from a compiled (.pyc or .pyo) file. This was due to marshal using
|
||
str(float) instead of repr(float) when building code objects. marshal
|
||
now uses repr(float) instead, which should reproduce floats to full
|
||
machine precision (assuming the platform C float<->string I/O conversion
|
||
functions are of good quality).
|
||
|
||
This may cause floating-point results to change in some cases, and
|
||
usually for the better, but may also cause numerically unstable
|
||
algorithms to break.
|
||
|
||
- The implementation of dicts suffers fewer collisions, which has speed
|
||
benefits. However, the order in which dict entries appear in dict.keys(),
|
||
dict.values() and dict.items() may differ from previous releases for a
|
||
given dict. Nothing is defined about this order, so no program should
|
||
rely on it. Nevertheless, it's easy to write test cases that rely on the
|
||
order by accident, typically because of printing the str() or repr() of a
|
||
dict to an "expected results" file. See Lib/test/test_support.py's new
|
||
sortdict(dict) function for a simple way to display a dict in sorted
|
||
order.
|
||
|
||
- Many other small changes to dicts were made, resulting in faster
|
||
operation along the most common code paths.
|
||
|
||
- Dictionary objects now support the "in" operator: "x in dict" means
|
||
the same as dict.has_key(x).
|
||
|
||
- The update() method of dictionaries now accepts generic mapping
|
||
objects. Specifically the argument object must support the .keys()
|
||
and __getitem__() methods. This allows you to say, for example,
|
||
{}.update(UserDict())
|
||
|
||
- Iterators were added; this is a generalized way of providing values
|
||
to a for loop. See PEP 234. There's a new built-in function iter()
|
||
to return an iterator. There's a new protocol to get the next value
|
||
from an iterator using the next() method (in Python) or the
|
||
tp_iternext slot (in C). There's a new protocol to get iterators
|
||
using the __iter__() method (in Python) or the tp_iter slot (in C).
|
||
Iterating (i.e. a for loop) over a dictionary generates its keys.
|
||
Iterating over a file generates its lines.
|
||
|
||
- The following functions were generalized to work nicely with iterator
|
||
arguments::
|
||
|
||
map(), filter(), reduce(), zip()
|
||
list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
|
||
max(), min()
|
||
join() method of strings
|
||
extend() method of lists
|
||
'x in y' and 'x not in y' (PySequence_Contains() in C API)
|
||
operator.countOf() (PySequence_Count() in C API)
|
||
right-hand side of assignment statements with multiple targets, such as ::
|
||
x, y, z = some_iterable_object_returning_exactly_3_values
|
||
|
||
- Accessing module attributes is significantly faster (for example,
|
||
random.random or os.path or yourPythonModule.yourAttribute).
|
||
|
||
- Comparing dictionary objects via == and != is faster, and now works even
|
||
if the keys and values don't support comparisons other than ==.
|
||
|
||
- Comparing dictionaries in ways other than == and != is slower: there were
|
||
insecurities in the dict comparison implementation that could cause Python
|
||
to crash if the element comparison routines for the dict keys and/or
|
||
values mutated the dicts. Making the code bulletproof slowed it down.
|
||
|
||
- Collisions in dicts are resolved via a new approach, which can help
|
||
dramatically in bad cases. For example, looking up every key in a dict
|
||
d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
|
||
faster now. Thanks to Christian Tismer for pointing out the cause and
|
||
the nature of an effective cure (last December! better late than never).
|
||
|
||
- repr() is much faster for large containers (dict, list, tuple).
|
||
|
||
|
||
Library
|
||
-------
|
||
|
||
- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
|
||
were added to the string module. These a locale-independent
|
||
constants, unlike letters, lowercase, and uppercase. These are now
|
||
use in appropriate locations in the standard library.
|
||
|
||
- The flags used in dlopen calls can now be configured using
|
||
sys.setdlopenflags and queried using sys.getdlopenflags.
|
||
|
||
- Fredrik Lundh's xmlrpclib is now a standard library module. This
|
||
provides full client-side XML-RPC support. In addition,
|
||
Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
|
||
one asyncore-based). Thanks to Eric Raymond for the documentation.
|
||
|
||
- The xrange() object is simplified: it no longer supports slicing,
|
||
repetition, comparisons, efficient 'in' checking, the tolist()
|
||
method, or the start, stop and step attributes. See PEP 260.
|
||
|
||
- A new function fnmatch.filter to filter lists of file names was added.
|
||
|
||
- calendar.py uses month and day names based on the current locale.
|
||
|
||
- strop is now *really* obsolete (this was announced before with 1.6),
|
||
and issues DeprecationWarning when used (except for the four items
|
||
that are still imported into string.py).
|
||
|
||
- Cookie.py now sorts key+value pairs by key in output strings.
|
||
|
||
- pprint.isrecursive(object) didn't correctly identify recursive objects.
|
||
Now it does.
|
||
|
||
- pprint functions now much faster for large containers (tuple, list, dict).
|
||
|
||
- New 'q' and 'Q' format codes in the struct module, corresponding to C
|
||
types "long long" and "unsigned long long" (on Windows, __int64). In
|
||
native mode, these can be used only when the platform C compiler supports
|
||
these types (when HAVE_LONG_LONG is #define'd by the Python config
|
||
process), and then they inherit the sizes and alignments of the C types.
|
||
In standard mode, 'q' and 'Q' are supported on all platforms, and are
|
||
8-byte integral types.
|
||
|
||
- The site module installs a new built-in function 'help' that invokes
|
||
pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
|
||
it displays a message reminding the user to use 'help()' or
|
||
'help(object)'.
|
||
|
||
Tests
|
||
-----
|
||
|
||
- New test_mutants.py runs dict comparisons where the key and value
|
||
comparison operators mutate the dicts randomly during comparison. This
|
||
rapidly causes Python to crash under earlier releases (not for the faint
|
||
of heart: it can also cause Win9x to freeze or reboot!).
|
||
|
||
- New test_pprint.py verifies that pprint.isrecursive() and
|
||
pprint.isreadable() return sensible results. Also verifies that simple
|
||
cases produce correct output.
|
||
|
||
C API
|
||
-----
|
||
|
||
- Removed the unused last_is_sticky argument from the internal
|
||
_PyTuple_Resize(). If this affects you, you were cheating.
|
||
|
||
----
|
||
|
||
**(For information about older versions, consult the HISTORY file.)**
|