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Update whatsnew document to use specific markup for identifiers, thus enabling cross-linking.

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Georg Brandl 2008-02-02 10:44:37 +00:00
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@ -79,7 +79,7 @@ and fast errors; it's the subtle behavioral changes in code that
remains syntactically valid that trips people up. I'm also omitting remains syntactically valid that trips people up. I'm also omitting
changes to rarely used features.) changes to rarely used features.)
* The ``print`` statement has been replaced with a ``print()`` function, * The ``print`` statement has been replaced with a :func:`print` function,
with keyword arguments to replace most of the special syntax of the with keyword arguments to replace most of the special syntax of the
old ``print`` statement (PEP 3105). Examples:: old ``print`` statement (PEP 3105). Examples::
@ -106,9 +106,9 @@ changes to rarely used features.)
There are <4294967296> possibilities! There are <4294967296> possibilities!
Notes about the ``print()`` function: Notes about the :func:`print` function:
* The ``print()`` function doesn't support the "softspace" feature of * The :func:`print` function doesn't support the "softspace" feature of
the old ``print`` statement. For example, in Python 2.x, the old ``print`` statement. For example, in Python 2.x,
``print "A\n", "B"`` would write ``"A\nB\n"``; but in Python 3.0, ``print "A\n", "B"`` would write ``"A\nB\n"``; but in Python 3.0,
``print("A\n", "B")`` writes ``"A\n B\n"``. ``print("A\n", "B")`` writes ``"A\n B\n"``.
@ -118,7 +118,7 @@ changes to rarely used features.)
``print(x)`` instead! ``print(x)`` instead!
* When using the ``2to3`` source-to-source conversion tool, all * When using the ``2to3`` source-to-source conversion tool, all
``print`` statements are autmatically converted to ``print()`` ``print`` statements are autmatically converted to :func:`print`
function calls, so this is mostly a non-issue for larger projects. function calls, so this is mostly a non-issue for larger projects.
* Python 3.0 uses strings and bytes instead of the Unicode strings and * Python 3.0 uses strings and bytes instead of the Unicode strings and
@ -131,19 +131,19 @@ changes to rarely used features.)
that if a file is opened using an incorrect mode or encoding, I/O that if a file is opened using an incorrect mode or encoding, I/O
will likely fail. will likely fail.
* ``map()`` and ``filter()`` return iterators. A quick fix is e.g. * :func:`map` and :func:`filter` return iterators. A quick fix is e.g.
``list(map(...))``, but a better fix is often to use a list ``list(map(...))``, but a better fix is often to use a list
comprehension (especially when the original code uses ``lambda``). comprehension (especially when the original code uses :keyword:`lambda`).
Particularly tricky is ``map()`` invoked for the side effects of the Particularly tricky is :func:`map` invoked for the side effects of the
function; the correct transformation is to use a for-loop. function; the correct transformation is to use a for-loop.
* ``dict`` methods ``.keys()``, ``.items()`` and ``.values()`` return * :class:`dict` methods :meth:`dict.keys`, :meth:`dict.items` and
views instead of lists. For example, this no longer works: :meth:`dict.values` return views instead of lists. For example, this no
``k = d.keys(); k.sort()``. Use ``k = sorted(d)`` instead. longer works: ``k = d.keys(); k.sort()``. Use ``k = sorted(d)`` instead.
* ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior. * ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior.
* The ``repr()`` of a long integer doesn't include the trailing ``L`` * The :func:`repr` of a long integer doesn't include the trailing ``L``
anymore, so code that unconditionally strips that character will anymore, so code that unconditionally strips that character will
chop off the last digit instead. chop off the last digit instead.
@ -151,32 +151,33 @@ changes to rarely used features.)
Strings and Bytes Strings and Bytes
================= =================
* There is only one string type; its name is ``str`` but its behavior * There is only one string type; its name is :class:`str` but its behavior and
and implementation are more like ``unicode`` in 2.x. implementation are like :class:`unicode` in 2.x.
* The ``basestring`` superclass has been removed. The ``2to3`` tool * The :class:`basestring` superclass has been removed. The ``2to3`` tool
replaces every occurence of ``basestring`` with ``str``. replaces every occurence of :class:`basestring` with :class:`str`.
* PEP 3137: There is a new type, ``bytes``, to represent binary data * PEP 3137: There is a new type, :class:`bytes`, to represent binary data (and
(and encoded text, which is treated as binary data until you decide encoded text, which is treated as binary data until you decide to decode it).
to decode it). The ``str`` and ``bytes`` types cannot be mixed; you The :class:`str` and :class:`bytes` types cannot be mixed; you must always
must always explicitly convert between them, using the ``.encode()`` explicitly convert between them, using the :meth:`str.encode` (str -> bytes)
(str -> bytes) or ``.decode()`` (bytes -> str) methods. or :meth:`bytes.decode` (bytes -> str) methods.
* PEP 3112: Bytes literals. E.g. b"abc". .. XXX add bytearray
* PEP 3112: Bytes literals, e.g. ``b"abc"``, create :class:`bytes` instances.
* PEP 3120: UTF-8 default source encoding. * PEP 3120: UTF-8 default source encoding.
* PEP 3131: Non-ASCII identifiers. (However, the standard library * PEP 3131: Non-ASCII identifiers. (However, the standard library remains
remains ASCII-only with the exception of contributor names in ASCII-only with the exception of contributor names in comments.)
comments.)
* PEP 3116: New I/O Implementation. The API is nearly 100% backwards * PEP 3116: New I/O Implementation. The API is nearly 100% backwards
compatible, but completely reimplemented (currently mostly in compatible, but completely reimplemented (currently mostly in Python). Also,
Python). Also, binary files use bytes instead of strings. binary files use bytes instead of strings.
* The ``StringIO`` and ``cStringIO`` modules are gone. Instead, * The :mod:`StringIO` and :mod:`cStringIO` modules are gone. Instead, import
import ``StringIO`` or ``BytesIO`` from the ``io`` module. :class:`io.StringIO` or :class:`io.BytesIO`.
PEP 3101: A New Approach to String Formatting PEP 3101: A New Approach to String Formatting
@ -184,20 +185,20 @@ PEP 3101: A New Approach to String Formatting
.. XXX expand this .. XXX expand this
* A new system for built-in string formatting operations replaces * A new system for built-in string formatting operations replaces the ``%``
the ``%`` string formatting operator. string formatting operator.
PEP 3106: Revamping dict ``.keys()``, ``.items()`` and ``.values()`` PEP 3106: Revamping dict :meth:`dict.keys`, :meth:`dict.items` and :meth:`dict.values`
==================================================================== ======================================================================================
.. XXX expand this .. XXX expand this
* The ``.iterkeys()``, ``.itervalues()`` and ``.iteritems()`` methods * The :meth:`dict.iterkeys`, :meth:`dict.itervalues` and :meth:`dict.iteritems`
have been removed. methods have been removed.
* ``.keys()``, ``.values()`` and ``.items()`` return objects with set * :meth:`dict.keys`, :meth:`dict.values` and :meth:`dict.items` return objects
behavior that reference the underlying dict. with set behavior that reference the underlying dict.
PEP 3107: Function Annotations PEP 3107: Function Annotations
@ -205,33 +206,31 @@ PEP 3107: Function Annotations
.. XXX expand this .. XXX expand this
* A standardized way of annotating a function's parameters and return * A standardized way of annotating a function's parameters and return values.
values.
Exception Stuff Exception Stuff
=============== ===============
* PEP 352: Exceptions must derive from BaseException. This is the * PEP 352: Exceptions must derive from :exc:`BaseException`. This is the root
root of the exception hierarchy. of the exception hierarchy.
* StandardException was removed (already in 2.6). * :exc:`StandardError` was removed (already in 2.6).
* Dropping sequence behavior (slicing!) and ``.message`` attribute of * Dropping sequence behavior (slicing!) and :attr:`message` attribute of
exception instances. exception instances.
* PEP 3109: Raising exceptions. You must now use ``raise * PEP 3109: Raising exceptions. You must now use ``raise Exception(args)``
Exception(args)`` instead of ``raise Exception, args``. instead of ``raise Exception, args``.
* PEP 3110: Catching exceptions. * PEP 3110: Catching exceptions.
* PEP 3134: Exception chaining. (The ``__context__`` feature from the * PEP 3134: Exception chaining. (The :attr:`__context__` feature from the PEP
PEP hasn't been implemented yet in 3.0a1.) hasn't been implemented yet in 3.0a2.)
* A few exception messages are improved when Windows fails to load an * A few exception messages are improved when Windows fails to load an extension
extension module. For example, ``error code 193`` is now ``%1 is not module. For example, ``error code 193`` is now ``%1 is not a valid Win32
a valid Win32 application``. Strings now deal with non-English application``. Strings now deal with non-English locales.
locales.
New Class and Metaclass Stuff New Class and Metaclass Stuff
@ -255,101 +254,97 @@ Other Language Changes
Here are most of the changes that Python 3.0 makes to the core Python Here are most of the changes that Python 3.0 makes to the core Python
language and built-in functions. language and built-in functions.
* Removed backticks (use ``repr()`` instead). * Removed backticks (use :func:`repr` instead).
* Removed ``<>`` (use ``!=`` instead). * Removed ``<>`` (use ``!=`` instead).
* ``!=`` now returns the opposite of ``==``, unless ``==`` returns * ``!=`` now returns the opposite of ``==``, unless ``==`` returns
``NotImplemented``. ``NotImplemented``.
* ``as`` and ``with`` are keywords. * :keyword:`as` and :keyword:`with` are keywords.
* ``True``, ``False``, and ``None`` are keywords. * ``True``, ``False``, and ``None`` are keywords.
* PEP 237: ``long`` renamed to ``int``. That is, there is only one * PEP 237: :class:`long` renamed to :class:`int`. That is, there is only one
built-in integral type, named ``int``; but it behaves like the old built-in integral type, named :class:`int`; but it behaves like the old
``long`` type, with the exception that the literal suffix ``L`` is :class:`long` type, with the exception that the literal suffix ``L`` is
neither supported by the parser nor produced by ``repr()`` anymore. neither supported by the parser nor produced by :func:`repr` anymore.
``sys.maxint`` was also removed since the int type has no maximum :data:`sys.maxint` was also removed since the int type has no maximum value
value anymore. anymore.
* PEP 238: int division returns a float. * PEP 238: int division returns a float.
* The ordering operators behave differently: for example, ``x < y`` * The ordering operators behave differently: for example, ``x < y`` where ``x``
where ``x`` and ``y`` have incompatible types raises ``TypeError`` and ``y`` have incompatible types raises :exc:`TypeError` instead of returning
instead of returning a pseudo-random boolean. a pseudo-random boolean.
* ``__getslice__()`` and friends killed. The syntax ``a[i:j]`` now * :meth:`__getslice__` and friends killed. The syntax ``a[i:j]`` now translates
translates to ``a.__getitem__(slice(i, j))`` (or ``__setitem__`` to ``a.__getitem__(slice(i, j))`` (or :meth:`__setitem__` or
or ``__delitem__``, depending on context). :meth:`__delitem__`, depending on context).
* PEP 3102: Keyword-only arguments. Named parameters occurring after * PEP 3102: Keyword-only arguments. Named parameters occurring after ``*args``
``*args`` in the parameter list *must* be specified using keyword in the parameter list *must* be specified using keyword syntax in the call.
syntax in the call. You can also use a bare ``*`` in the parameter You can also use a bare ``*`` in the parameter list to indicate that you don't
list to indicate that you don't accept a variable-length argument accept a variable-length argument list, but you do have keyword-only
list, but you do have keyword-only arguments. arguments.
* PEP 3104: ``nonlocal`` statement. Using ``nonlocal x`` you can now * PEP 3104: :keyword:`nonlocal` statement. Using ``nonlocal x`` you can now
assign directly to a variable in an outer (but non-global) scope. assign directly to a variable in an outer (but non-global) scope.
* PEP 3111: ``raw_input()`` renamed to ``input()``. That is, the new * PEP 3111: :func:`raw_input` renamed to :func:`input`. That is, the new
``input()`` function reads a line from ``sys.stdin`` and returns it :func:`input` function reads a line from :data:`sys.stdin` and returns it with
with the trailing newline stripped. It raises ``EOFError`` if the the trailing newline stripped. It raises :exc:`EOFError` if the input is
input is terminated prematurely. To get the old behavior of terminated prematurely. To get the old behavior of :func:`input`, use
``input()``, use ``eval(input())``. ``eval(input())``.
* ``xrange()`` renamed to ``range()``. * :func:`xrange` renamed to :func:`range`.
* PEP 3113: Tuple parameter unpacking removed. You can no longer write * PEP 3113: Tuple parameter unpacking removed. You can no longer write ``def
``def foo(a, (b, c)): ...``. Use ``def foo(a, b_c): b, c = b_c`` foo(a, (b, c)): ...``. Use ``def foo(a, b_c): b, c = b_c`` instead.
instead.
* PEP 3114: ``.next()`` renamed to ``.__next__()``, new builtin * PEP 3114: ``.next()`` renamed to :meth:`__next__`, new builtin :func:`next` to
``next()`` to call the ``__next__()`` method on an object. call the :meth:`__next__` method on an object.
* PEP 3127: New octal literals; binary literals and ``bin()``. * PEP 3127: New octal literals; binary literals and :func:`bin`. Instead of
Instead of ``0666``, you write ``0o666``. The oct() function is ``0666``, you write ``0o666``. The :func:`oct` function is modified
modified accordingly. Also, ``0b1010`` equals 10, and ``bin(10)`` accordingly. Also, ``0b1010`` equals 10, and ``bin(10)`` returns
returns ``"0b1010"``. ``0666`` is now a ``SyntaxError``. ``"0b1010"``. ``0666`` is now a :exc:`SyntaxError`.
* PEP 3132: Extended Iterable Unpacking. You can now write things * PEP 3132: Extended Iterable Unpacking. You can now write things like ``a, b,
like ``a, b, *rest = some_sequence``. And even ``*rest, a = *rest = some_sequence``. And even ``*rest, a = stuff``. The ``rest`` object
stuff``. The ``rest`` object is always a list; the right-hand is always a list; the right-hand side may be any iterable.
side may be any iterable.
* PEP 3135: New ``super()``. You can now invoke ``super()`` without * PEP 3135: New :func:`super`. You can now invoke :func:`super` without
arguments and the right class and instance will automatically be arguments and the right class and instance will automatically be chosen. With
chosen. With arguments, its behavior is unchanged. arguments, its behavior is unchanged.
* ``zip()``, ``map()`` and ``filter()`` return iterators. * :func:`zip`, :func:`map` and :func:`filter` return iterators.
* ``string.letters`` and its friends (``.lowercase`` and * :data:`string.letters` and its friends (:data:`string.lowercase` and
``.uppercase``) are gone. Use ``string.ascii_letters`` :data:`string.uppercase`) are gone. Use :data:`string.ascii_letters`
etc. instead. etc. instead.
* Removed: ``apply()``, ``callable()``, ``coerce()``, ``execfile()``, * Removed: :func:`apply`, :func:`callable`, :func:`coerce`, :func:`execfile`,
``file()``, ``reduce()``, ``reload()``. :func:`file`, :func:`reduce`, :func:`reload`.
* Removed: ``dict.has_key()``. * Removed: :meth:`dict.has_key`.
* ``exec`` is now a function. * :func:`exec` is now a function.
* There is a new free format floating point representation, which is * There is a new free format floating point representation, which is based on
based on "Floating-Point Printer Sample Code", by Robert G. Burger. "Floating-Point Printer Sample Code", by Robert G. Burger. ``repr(11./5)``
``repr(11./5)`` now returns ``2.2`` instead of ``2.2000000000000002``. now returns ``2.2`` instead of ``2.2000000000000002``.
* The ``__oct__()`` and ``__hex__()`` special methods are removed -- * The :meth:`__oct__` and :meth:`__hex__` special methods are removed --
``oct()`` and ``hex()`` use ``__index__()`` now to convert the :func:`oct` and :func:`hex` use :meth:`__index__` now to convert the argument
argument to an integer. to an integer.
* There is now a ``bin()`` builtin function. * Support is removed for :attr:`__members__` and :attr:`__methods__`.
* Support is removed for ``__members__`` and ``__methods__``. * Renamed the boolean conversion C-level slot and method: ``nb_nonzero`` is now
``nb_bool`` and :meth:`__nonzero__` is now :meth:`__bool__`.
* ``nb_nonzero`` is now ``nb_bool`` and ``__nonzero__`` is now * Removed :data:`sys.maxint`. Use :data:`sys.maxsize`.
``__bool__``.
* Removed ``sys.maxint``. Use ``sys.maxsize``.
.. ====================================================================== .. ======================================================================
@ -360,10 +355,10 @@ Optimizations
* Detailed changes are listed here. * Detailed changes are listed here.
The net result of the 3.0 generalizations is that Python 3.0 runs the The net result of the 3.0 generalizations is that Python 3.0 runs the pystone
pystone benchmark around 33% slower than Python 2.5. There's room for benchmark around 33% slower than Python 2.5. There's room for improvement; we
improvement; we expect to be optimizing string and integer operations expect to be optimizing string and integer operations significantly before the
significantly before the final 3.0 release! final 3.0 release!
.. ====================================================================== .. ======================================================================
@ -371,26 +366,27 @@ significantly before the final 3.0 release!
New, Improved, and Deprecated Modules New, Improved, and Deprecated Modules
===================================== =====================================
As usual, Python's standard library received a number of enhancements As usual, Python's standard library received a number of enhancements and bug
and bug fixes. Here's a partial list of the most notable changes, fixes. Here's a partial list of the most notable changes, sorted alphabetically
sorted alphabetically by module name. Consult the :file:`Misc/NEWS` by module name. Consult the :file:`Misc/NEWS` file in the source tree for a more
file in the source tree for a more complete list of changes, or look complete list of changes, or look through the Subversion logs for all the
through the Subversion logs for all the details. details.
* The ``cPickle`` module is gone. Use ``pickle`` instead. Eventually * The :mod:`cPickle` module is gone. Use :mod:`pickle` instead. Eventually
we'll have a transparent accelerator module. we'll have a transparent accelerator module.
* The ``imageop`` module is gone. * The :mod:`imageop` module is gone.
* The ``audiodev``, ``Bastion``, ``bsddb185``, ``exceptions``, * The :mod:`audiodev`, :mod:`Bastion`, :mod:`bsddb185`, :mod:`exceptions`,
``linuxaudiodev``, ``md5``, ``MimeWriter``, ``mimify``, ``popen2``, :mod:`linuxaudiodev`, :mod:`md5`, :mod:`MimeWriter`, :mod:`mimify`,
``rexec``, ``sets``, ``sha``, ``stringold``, ``strop``, ``sunaudiodev``, :mod:`popen2`, :mod:`rexec`, :mod:`sets`, :mod:`sha`, :mod:`stringold`,
``timing``, and ``xmllib`` modules are gone. :mod:`strop`, :mod:`sunaudiodev`, :mod:`timing`, and :mod:`xmllib` modules are
gone.
* The ``new`` module is gone. * The :mod:`new` module is gone.
* The methods ``os.tmpnam()``, ``os.tempnam()`` and ``os.tmpfile()`` have * The functions :func:`os.tmpnam`, :func:`os.tempnam` and :func:`os.tmpfile`
been removed in favor of the ``tempfile`` module. have been removed in favor of the :mod:`tempfile` module.
.. ====================================================================== .. ======================================================================
.. whole new modules get described in subsections here .. whole new modules get described in subsections here
@ -407,15 +403,15 @@ Changes to Python's build process and to the C API include:
* PEP 3121: Extension Module Initialization & Finalization. * PEP 3121: Extension Module Initialization & Finalization.
* PEP 3123: Making ``PyObject_HEAD`` conform to standard C. * PEP 3123: Making :cmacro:`PyObject_HEAD` conform to standard C.
* No more C API support for restricted execution. * No more C API support for restricted execution.
* ``PyNumber_Coerce()``, ``PyNumber_CoerceEx()``, ``PyMember_Get``, * :cfunc:`PyNumber_Coerce`, :cfunc:`PyNumber_CoerceEx`, :cfunc:`PyMember_Get`,
and ``PyMember_Set`` C APIs are removed. and :cfunc:`PyMember_Set` C APIs are removed.
* New C API ``PyImport_ImportModuleNoBlock()``, works like * New C API :cfunc:`PyImport_ImportModuleNoBlock`, works like
``PyImport_ImportModule()`` but won't block on the import lock (returning :cfunc:`PyImport_ImportModule` but won't block on the import lock (returning
an error instead). an error instead).
.. ====================================================================== .. ======================================================================