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 3.0a3?
===========================

*Release data: XX-XXX-2008*

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

- 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 #1580: New free format floating point representation based on 
  "Floating-Point Printer Sample Code", by Robert G. Burger. For example
  repr(11./5) now returns '2.2' instead of '2.2000000000000002'.

- 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


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


Library
-------

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

- Issue #1578: Problems in win_getpass


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
-----

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.)**