cpython/Misc/NEWS

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Python News
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(editors: check NEWS.help for information about editing NEWS using ReST.)

What's New in Python 3.0a4?
===========================

*Release date: XX-XXX-2008*

Core and Builtins
-----------------

- Bug #2301: Don't try decoding the source code into the original
  encoding for syntax errors.

Extension Modules
-----------------

- The dl module was removed, use the ctypes module instead.

- Use wchar_t functions in _locale module.

Library
-------

- The class distutils.commands.build_py.build_py_2to3 can be used
  as a build_py replacement to automatically run 2to3 on modules
  that are going to be installed.

- A new pickle protocol (protocol 3) is added with explicit support
  for bytes.  This is the default protocol.  It intentionally cannot
  be unpickled by Python 2.x.

- When a pickle written by Python 2.x contains an (8-bit) str
  instance, this is now decoded to a (Unicode) str instance.  The
  encoding used to do this defaults to ASCII, but can be overridden
  via two new keyword arguments to the Unpickler class.  Previously
  this would create bytes instances, which is usually wrong: str
  instances are often used to pickle attribute names etc., and text is
  more common than binary data anyway.

- Default to ASCII as the locale.getpreferredencoding, if the POSIX
  system doesn't support CODESET and LANG isn't set or doesn't
  allow deduction of an encoding.

- Issue #1202: zlib.crc32 and zlib.adler32 now return an unsigned value.

- Issue #719888: Updated tokenize to use a bytes API. generate_tokens has been
  renamed tokenize and now works with bytes rather than strings. A new
  detect_encoding function has been added for determining source file encoding
  according to PEP-0263. Token sequences returned by tokenize always start
  with an ENCODING token which specifies the encoding used to decode the file.
  This token is used to encode the output of untokenize back to bytes.

What's New in Python 3.0a3?
===========================

*Release date: 29-Feb-2008*

Core and Builtins
-----------------

- Issue #2282: io.TextIOWrapper was not overriding seekable() from io.IOBase.

- Issue #2115: Important speedup in setting __slot__ attributes.  Also 
  prevent a possible crash: an Abstract Base Class would try to access a slot 
  on a registered virtual subclass.

- Fixed repr() and str() of complex numbers with infinity or nan as real or
  imaginary part.

- Clear all free list during a gc.collect() of the highest generation in order
  to allow pymalloc to free more arenas. Python may give back memory to the
  OS earlier.

- Issue #2045: Fix an infinite recursion triggered when printing a subclass of
  collections.defaultdict, if its default_factory is set to a bound method.

- Fixed a minor memory leak in dictobject.c. The content of the free
  list was not freed on interpreter shutdown.

- Limit free list of method and builtin function objects to 256 entries
  each.

- Patch #1953: Added ``sys._compact_freelists()`` and the C API functions
  ``PyInt_CompactFreeList`` and ``PyFloat_CompactFreeList``
  to compact the internal free lists of pre-allocted ints and floats.

- Bug #1983: Fixed return type of fork(), fork1() and forkpty() calls.
  Python expected the return type int but the fork familie returns pi_t.

- Issue #1678380: Fix a bug that identifies 0j and -0j when they appear
  in the same code unit.

- Issue #2025 :  Add tuple.count() and tuple.index() methods to comply with
  the collections.Sequence API.

- Fixed multiple reinitialization of the Python interpreter. The small int
  list in longobject.c has caused a seg fault during the third finalization.

- Issue #1973: bytes.fromhex('') raises SystemError

- Issue #1771: remove cmp parameter from sorted() and list.sort()

- Issue #1969: split and rsplit in bytearray are inconsistent

- map() and no longer accepts None for the first argument.
  Use zip() instead.

- Issue #1769: Now int("- 1") is not allowed any more.

- Object/longobject.c: long(float('nan')) raises an OverflowError instead
  of returning 0.

- Issue #1762972: __file__ points to the source file instead of the pyc/pyo
  file if the py file exists.

- Issue #1393: object_richcompare() returns NotImplemented instead of
  False if the objects aren't equal, to give the other side a chance.

- Issue #1692: Interpreter was not displaying location of SyntaxError.

- Improve some exception messages when Windows fails to load an extension
  module. Now we get for example '%1 is not a valid Win32 application' instead
  of 'error code 193'.  Also use Unicode strings to deal with non-English
  locales.

- Issue #1587: Added instancemethod wrapper for PyCFunctions. The Python C API
  has gained a new type *PyInstanceMethod_Type* and the functions
  *PyInstanceMethod_Check(o)*, *PyInstanceMethod_New(func)* and
  *PyInstanceMethod_Function(im)*.

- Constants gc.DEBUG_OBJECT and gc.DEBUG_INSTANCE have been removed from the
  gc module; gc.DEBUG_COLLECTABLE or gc.DEBUG_UNCOLLECTABLE are now enough to
  print the corresponding list of objects considered by the garbage collector.

- Issue #1573: Improper use of the keyword-only syntax makes the parser crash.

- Issue #1564: The set implementation should special-case PyUnicode instead
  of PyString.

- Patch #1031213: Decode source line in SyntaxErrors back to its
  original source encoding.

- inspect.getsource() includes the decorators again.

- Bug #1713: posixpath.ismount() claims symlink to a mountpoint is a
  mountpoint.

- Fix utf-8-sig incremental decoder, which didn't recognise a BOM when the
  first chunk fed to the decoder started with a BOM, but was longer than 3
  bytes.


Extension Modules
-----------------

- Code for itertools ifilter(), imap(), and izip() moved to bultins and
  renamed to filter(), map(), and zip().  Also, renamed izip_longest()
  to zip_longest() and ifilterfalse() to filterfalse().

- Issue #1762972: Readded the reload() function as imp.reload()

- Bug #2111: mmap segfaults when trying to write a block opened with PROT_READ

- #2063: correct order of utime and stime in os.times() result on Windows.


Library
-------

- Weakref dictionaries now inherit from MutableMapping.
  XXX their API still needs to be modernized (i.e. eliminate the iter methods).

- Created new UserDict class in collections module.  This one inherits from and
  complies with the MutableMapping ABC.  Also, moved UserString and UserList
  to the collections module.  The MutableUserString class was removed.

- Removed UserDict.DictMixin.  Replaced all its uses with
  collections.MutableMapping.

- Issue #1703: getpass() should flush after writing prompt.

- Issue #1585: IDLE uses non-existent xrange() function.

- Issue #1578: Problems in win_getpass.

Build
-----

- Renamed --enable-unicode configure flag to --with-wide-unicode, since
  Unicode strings can't be disabled anymore.


C API
-----

- Issue #1629: Renamed Py_Size, Py_Type and Py_Refcnt to Py_SIZE,
  Py_TYPE and Py_REFCNT.

- New API PyImport_ImportModuleNoBlock(), works like PyImport_ImportModule()
  but won't block on the import lock (returning an error instead).


What's New in Python 3.0a2?
===========================

*Release date: 07-Dec-2007*

(Note: this list is incomplete.)

Core and Builtins
-----------------

- str8 now has the same construction signature as bytes.

- Comparisons between str and str8 now return False/True for ==/!=.  sqlite3
  returns str8 when recreating on object from it's __conform__ value.  The
  struct module returns str8 for all string-related formats.  This was true
  before this change, but becomes more apparent thanks to string comparisons
  always being False.

- Replaced `PyFile_FromFile()` with `PyFile_FromFd(fd, name. mode, buffer, 
  encoding, newline)`

- Fixed `imp.find_module()` to obey the -*- coding: -*- header.

- Changed `__file__` and `co_filename` to unicode. The path names are decoded
  with `Py_FileSystemDefaultEncoding` and a new API method 
  `PyUnicode_DecodeFSDefault(char*)` was added.

- io.open() and _fileio.FileIO have grown a new argument closefd. A false
  value disables the closing of the file descriptor.

- Added a new option -b to issues warnings (-bb for errors) about certain
  operations between bytes/buffer and str like str(b'') and comparsion.

- The standards streams sys.stdin, stdout and stderr may be None when the
  when the C runtime library returns an invalid file descriptor for the
  streams (fileno(stdin) < 0). For now this happens only for Windows GUI
  apps and scripts started with `pythonw.exe`.

- Added PCbuild9 directory for VS 2008.

- Renamed structmember.h WRITE_RESTRICTED to PY_WRITE_RESTRICTED to work
  around a name clash with VS 2008 on Windows.

- Unbound methods are gone for good. ClassObject.method returns an ordinary
  function object, instance.method still returns a bound method object.
  The API of bound methods is cleaned up, too. The im_class attribute is
  removed and im_func + im_self are renamed to __func__ and __self__. The
  factory PyMethod_New takes only func and instance as argument.

- intobject.h is no longer included by Python.h. The remains were moved
  to longobject.h. It still exists to define several aliases from PyInt_
  to PyLong_ functions.

- Removed sys.maxint, use sys.maxsize instead.


Extension Modules
-----------------

- The `hotshot` profiler has been removed; use `cProfile` instead.


Library
-------

- When loading an external file using testfile(), the passed-in encoding
  argument was being ignored if __loader__ is defined and forcing the source to
  be UTF-8.

- The methods `os.tmpnam()`, `os.tempnam()` and `os.tmpfile()` have been
  removed in favor of the tempfile module.

- Removed the 'new' module.

- Removed all types from the 'types' module that are easily accessable through
  builtins.


What's New in Python 3.0a1?
==========================

*Release date: 31-Aug-2007*

Core and Builtins
-----------------

- PEP 3131: Support non-ASCII identifiers.

- PEP 3120: Change default encoding to UTF-8.

- PEP 3123: Use proper C inheritance for PyObject.

- Removed the __oct__ and __hex__ special methods and added a bin()
  builtin function.

- PEP 3127: octal literals now start with "0o". Old-style octal literals
  are invalid. There are binary literals with a prefix of "0b".
  This also affects int(x, 0).

- None, True, False are now keywords.

- PEP 3119: isinstance() and issubclass() can be overridden.

- Remove BaseException.message.

- Remove tuple parameter unpacking (PEP 3113).

- Remove the f_restricted attribute from frames.  This naturally leads to the
  removal of PyEval_GetRestricted() and PyFrame_IsRestricted().

- PEP 3132 was accepted. That means that you can do ``a, *b = range(5)``
  to assign 0 to a and [1, 2, 3, 4] to b.

- range() now returns an iterator rather than a list.  Floats are not allowed.
  xrange() is no longer defined.

- Patch #1660500: hide iteration variable in list comps, add set comps
  and use common code to handle compilation of iterative expressions

- By default, != returns the opposite of ==, unless the latter returns
  NotImplemented.

- Patch #1680961: sys.exitfunc has been removed and replaced with a private
  C-level API.

- PEP 3115: new metaclasses: the metaclass is now specified as a
  keyword arg in the class statement, which can now use the full syntax of
  a parameter list. Also, the metaclass can implement a __prepare__ function
  which will be called to create the dictionary for the new class namespace.

- The long-deprecated argument "pend" of PyFloat_FromString() has been
  removed.

- The dir() function has been extended to call the __dir__() method on
  its argument, if it exists. If not, it will work like before. This allows
  customizing the output of dir() in the presence of a __getattr__().

- Removed support for __members__ and __methods__.

- Removed indexing/slicing on BaseException.

- input() became raw_input(): the name input() now implements the
  functionality formerly known as raw_input(); the name raw_input()
  is no longer defined.

- Classes listed in an 'except' clause must inherit from BaseException.

- PEP 3106: dict.iterkeys(), .iteritems(), .itervalues() are now gone;
  and .keys(), .items(), .values() return dict views, which behave
  like sets.

- PEP 3105: print is now a function.  Also (not in the PEP) the
  'softspace' attribute of files is now gone (since print() doesn't use
  it).  A side effect of this change is that you can get incomplete
  output lines in interactive sessions:

  >>> print(42, end="")
  42>>>

  We may be able to fix this after the I/O library rewrite.

- PEP 3102: keyword-only arguments.

- Int/Long unification is complete.  The 'long' built-in type
  and literals with trailing 'L' or 'l' have been removed.
  Performance may be sub-optimal (haven't really benchmarked).

- 'except E, V' must now be spelled as 'except E as V' and deletes V
  at the end of the except clause; V must be a simple name.

- Added function annotations per PEP 3107.

- Added nonlocal declaration from PEP 3104

  >>> def f(x):
  ...     def inc():
  ...         nonlocal x
  ...         x += 1
  ...         return x
  ...     return inc
  ...
  >>> inc = f(0)
  >>> inc()
  1
  >>> inc()
  2

- Moved intern() to sys.intern().

- exec is now a function.

- Renamed nb_nonzero to nb_bool and __nonzero__ to __bool__.

- Classic classes are a thing of the past.  All classes are new style.

- Exceptions *must* derive from BaseException.

- Integer division always returns a float.  The -Q option is no more.
  All the following are gone:
   * PyNumber_Divide and PyNumber_InPlaceDivide
   * __div__, __rdiv__, and __idiv__
   * nb_divide, nb_inplace_divide
   * operator.div, operator.idiv, operator.__div__, operator.__idiv__
  (Only __truediv__ and __floordiv__ remain, not sure how to handle them
   if we want to re-use __div__ and friends.  If we do, it will make
   it harder to write code for both 2.x and 3.x.)

- 'as' and 'with' are keywords.

- Absolute import is the default behavior for 'import foo' etc.

- Removed support for syntax:
  backticks (ie, `x`), <>

- Removed these Python builtins:
  apply(), callable(), coerce(), execfile(), file(), reduce(), reload()

- Removed these Python methods:
  {}.has_key

- Removed these opcodes:
  BINARY_DIVIDE, INPLACE_DIVIDE, UNARY_CONVERT

- Remove C API support for restricted execution.

- zip(), map() and filter() now return iterators, behaving like their
  itertools counterparts. This also affect map()'s behavior on
  sequences of unequal length -- it now stops after the shortest one
  is exhausted.

- Additions:
  set literals, set comprehensions, ellipsis literal.

- Added class decorators per PEP 3129.


Extension Modules
-----------------

- Remove the imageop module.  Obsolete long with its unit tests becoming
  useless from the removal of rgbimg and imgfile.

- Removed these attributes from Python modules:
  * operator module: div, idiv, __div__, __idiv__, isCallable, sequenceIncludes
  * sys module: exc_clear(), exc_type, exc_value, exc_traceback


Library
-------

- Remove the compiler package.  Use of the _ast module and (an eventual)
  AST -> bytecode mechanism.

- Removed these modules:
  * audiodev, Bastion, bsddb185, exceptions, linuxaudiodev,
    md5, MimeWriter, mimify, popen2,
    rexec, sets, sha, stringold, strop, sunaudiodev, timing, xmllib.

- Moved these modules to Tools/Demos:
  * toaiff

- Remove obsolete IRIX modules: al/AL, cd/CD, cddb, cdplayer, cl/CL, DEVICE,
  ERRNO, FILE, fl/FL, flp, fm, GET, gl/GL, GLWS, IN, imgfile, IOCTL, jpeg,
  panel, panelparser, readcd, sgi, sv/SV, torgb, WAIT.

- Remove obsolete functions:
  * commands.getstatus(), os.popen*,

- Remove functions in the string module that are also string methods;
  Remove string.{letters, lowercase, uppercase}.

- Remove support for long obsolete platforms: plat-aix3, plat-irix5.

- Remove xmlrpclib.SlowParser.  It was based on xmllib.

- Patch #1680961: atexit has been reimplemented in C.

- Add new codecs for UTF-32, UTF-32-LE and UTF-32-BE.


Build
-----

C API
-----

- Removed these Python slots:
  __coerce__, __div__, __idiv__, __rdiv__

- Removed these C APIs:
  PyNumber_Coerce(), PyNumber_CoerceEx(), PyMember_Get, PyMember_Set

- Removed these C slots/fields:
  nb_divide, nb_inplace_divide

- Removed these macros:
  staticforward, statichere, PyArg_GetInt, PyArg_NoArgs, _PyObject_Del

- Removed these typedefs:
  intargfunc, intintargfunc, intobjargproc, intintobjargproc,
  getreadbufferproc, getwritebufferproc, getsegcountproc, getcharbufferproc,
  memberlist


Tests
-----

- Removed test.testall as test.regrtest replaces it.


Documentation
-------------

Mac
---

- The cfmfile was removed.


Platforms
---------

- Support for BeOS and AtheOS was removed (according to PEP 11).

- Support for RiscOS, Irix, Tru64 was removed (alledgedly).


Tools/Demos
-----------

**(For information about older versions, consult the HISTORY file.)**