guido.van.rossum
2008-12-02 22:34:15 UTC
Author: guido.van.rossum
Date: Tue Dec 2 23:34:15 2008
New Revision: 67479
Log:
Another checkpoint. More XXXes added...
Also add some labels to 2.6.rst and howto/unicode.rst so I can refer
to them. (Somehow a label named 'module-contextlib' couldn't be
referenced -- why???)
Modified:
python/branches/py3k/Doc/howto/unicode.rst
python/branches/py3k/Doc/whatsnew/2.6.rst
python/branches/py3k/Doc/whatsnew/3.0.rst
Modified: python/branches/py3k/Doc/howto/unicode.rst
==============================================================================
--- python/branches/py3k/Doc/howto/unicode.rst (original)
+++ python/branches/py3k/Doc/howto/unicode.rst Tue Dec 2 23:34:15 2008
@@ -1,3 +1,5 @@
+.. _unicode-howto:
+
*****************
Unicode HOWTO
*****************
Modified: python/branches/py3k/Doc/whatsnew/2.6.rst
==============================================================================
--- python/branches/py3k/Doc/whatsnew/2.6.rst (original)
+++ python/branches/py3k/Doc/whatsnew/2.6.rst Tue Dec 2 23:34:15 2008
@@ -1,3 +1,5 @@
+.. _whats-new-in-2.6:
+
****************************
What's New in Python 2.6
****************************
@@ -244,6 +246,8 @@
The underlying reStructuredText parser and toolset.
+.. _pep-0343:
+
PEP 343: The 'with' statement
=============================
@@ -424,7 +428,7 @@
# return False
-.. _module-contextlib:
+.. _new-module-contextlib:
The contextlib module
---------------------
Modified: python/branches/py3k/Doc/whatsnew/3.0.rst
==============================================================================
--- python/branches/py3k/Doc/whatsnew/3.0.rst (original)
+++ python/branches/py3k/Doc/whatsnew/3.0.rst Tue Dec 2 23:34:15 2008
@@ -2,9 +2,9 @@
What's New In Python 3.0
****************************
-.. XXX add trademark info for Apple, Microsoft, SourceForge.
+.. XXX Add trademark info for Apple, Microsoft.
-.. XXX turn all PEP references into :pep:`NNN` markup.
+.. XXX Remove duplicates; just put info in the most relevant section.
:Author: Guido van Rossum
:Release: |release|
@@ -53,11 +53,12 @@
when researching a change.
This article explains the new features in Python 3.0, compared to 2.6.
-Python 3.0 is the first ever *intentionally incompatible* release.
-There are more changes than in a typical release, and more that are
-important for all Python users. Nevertheless, after digesting the
-changes, you'll find that Python really hasn't changed all that much
--- by and large, we're merely fixing well-known annoyances and warts.
+Python 3.0, also known as "Python 3000" or "Py3k", is the first ever
+*intentionally incompatible* release. There are more changes than in
+a typical release, and more that are important for all Python users.
+Nevertheless, after digesting the changes, you'll find that Python
+really hasn't changed all that much -- by and large, we're merely
+fixing well-known annoyances and warts.
This article doesn't attempt to provide a complete specification of
the new features, but instead provides a convenient overview. For
@@ -79,16 +80,15 @@
Common Stumbling Blocks
=======================
-This section briefly lists a few changes that are more likely to trip
-people up, without necessarily raising obvious errors. Most issues
-are explained in more detail in later sections.
+This section lists those few changes that are most likely to trip you
+up if you're used to Python 2.5.
Print Is A Function
-------------------
-The ``print`` statement has been replaced with a :func:`print` function,
-with keyword arguments to replace most of the special syntax of the
-old ``print`` statement (PEP 3105). Examples::
+The :keyword:`print` statement has been replaced with a :func:`print`
+function, with keyword arguments to replace most of the special syntax
+of the old :keyword:`print` statement (:pep:`3105`). Examples::
Old: print "The answer is", 2*2
New: print("The answer is", 2*2)
@@ -116,7 +116,7 @@
Note:
* The :func:`print` function doesn't support the "softspace" feature of
- the old ``print`` statement. For example, in Python 2.x,
+ the old :keyword:`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")`` writes ``"A\n B\n"``.
@@ -125,14 +125,16 @@
``print(x)`` instead!
* When using the ``2to3`` source-to-source conversion tool, all
- ``print`` statements are automatically converted to :func:`print`
- function calls, so this is mostly a non-issue for larger projects.
+ :keyword:`print` statements are automatically converted to
+ :func:`print` function calls, so this is mostly a non-issue for
+ larger projects.
Text Strings Vs. Bytes
----------------------
Everything you thought you knew about binary data and Unicode has
-changed:
+changed. There's a longer section below; here's a summary of the
+changes:
* Python 3.0 uses *strings* and *bytes* instead of *Unicode strings*
and *8-bit strings*. The difference is that any attempt to mix
@@ -157,10 +159,12 @@
reading or writing more than pure ASCII text should probably have a
way to override the encoding.
-* XXX More below?
+* The builtin :class:`basestring` abstract type was removed. Use
+ :class:`str` instead. The :class:`str` and :class:`bytes` types
+ don't have functionality enough in common to warrant a shared base
+ class.
-* See also the *Unicode HOWTO*. (XXX How to make this a link?)
- (XXX Move to longer section below?)
+* See also the :ref:`unicode-howto`, which was updated for Python 3.0.
Views And Interators Instead Of Lists
-------------------------------------
@@ -219,15 +223,13 @@
Integers
--------
-* We unified the :class:`int` and :class:`long` types. All integers
- are now of type :class:`int`.
-
-* ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior.
- (The latter syntax has existed for years, at least since Python 2.2.)
+* :pep:`0237`: :class:`long` renamed to :class:`int`. That is, there
+ is only one built-in integral type, named :class:`int`; but it
+ behaves mostly like the old :class:`long` type.
* The :func:`repr` of a long integer doesn't include the trailing ``L``
anymore, so code that unconditionally strips that character will
- chop off the last digit instead.
+ chop off the last digit instead. (Use :func:`str` instead.)
* The :data:`sys.maxint` constant was removed, since there is no
longer a limit to the value of ints. However, :data:`sys.maxsize`
@@ -236,7 +238,9 @@
and is typically the same as :data:`sys.maxint` in previous releases
on the same platform (assuming the same build options).
-* XXX More below?
+* ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior.
+ (The latter syntax has existed for years, at least since Python 2.2.)
+ See :pep:`0238`.
Overview Of Syntactic Changes
@@ -245,35 +249,42 @@
This section gives a brief overview of every *syntactic* change.
Several of these are discussed at greater length later.
-XXX Did I get everything?
-
Additions
---------
* Function argument and return value annotations (see below). XXX
-* A lone ``*`` in a formal parameter list implies that any following
- arguments *must* be specified in keyword form. (XXX Didn't this make
- it into 2.6 as well?)
+* :pep:`3102`: Keyword-only arguments. Named parameters occurring
+ after ``*args`` in the parameter list *must* be specified using
+ keyword syntax in the call. You can also use a bare ``*`` in the
+ parameter list to indicate that you don't accept a variable-length
+ argument list, but you do have keyword-only arguments.
* Keyword arguments are allowed after the list of base classes in a
class definition. This is used by the new convention for specifying
a metaclass, but can be used for other purposes as well, as long as
the metaclass supports it.
-* Tuple-unpacking assignment now has a *wildcard* syntax, e.g.::
+* :pep:`3104`: :keyword:`nonlocal` statement. Using ``nonlocal x``
+ you can now assign directly to a variable in an outer (but
+ non-global) scope. :keyword:`nonlocal` is a new reserved word.
+
+* :pep:`3132`: Extended Iterable Unpacking. You can now write things
+ like ``a, b, *rest = some_sequence``. And even ``*rest, a =
+ stuff``. The ``rest`` object is always a (possibly empty) list; the
+ right-hand side may be any iterable. Example::
- (a, b, *rest) = range(5)
+ (a, *rest, b) = range(5)
- This sets *a* to 0, *b* to 1, and \*rest to ``[2, 3, 4]``.
+ This sets *a* to ``0``, *b* to ``4``, and \*rest to ``[1, 2, 3]``.
* Dictionary comprehensions: ``{k: v for k, v in stuff}`` means the
same thing as ``dict(stuff)`` but is more flexible.
* Set literals, e.g. ``{1, 2}``. Note that ``{}`` is an empty
- dictionary; use ``set()`` for an empty set. Set comprehensions
- are also supported; ``{x for x in stuff}`` means the same thing
- as ``set(stuff)`` but is more flexible.
+ dictionary; use ``set()`` for an empty set. Set comprehensions are
+ also supported; ``{x for x in stuff}`` means the same thing as
+ ``set(stuff)`` but is more flexible.
* New octal literals, e.g. ``0o720`` (already in 2.6). The old octal
literals (``0720``) are gone.
@@ -286,118 +297,169 @@
-------
* New :keyword:`raise` statement syntax: ``raise [expr [from expr]]``.
+ Also note that string exceptions are no longer legal (:pep:`0352`).
-* New keywords: :keyword:`as`, :keyword:`with` (already in 2.6),
- :keyword:`None` (partially enforced in 2.6), :keyword:`True`,
- :keyword:`False` (these were built-ins previously), and
- :keyword:`nonlocal` (for the new ``nonlocal`` statement).
-
-* Change from ``except exc, var:`` to ``except exc as var:``. XXX
-
-* *Very* subtle changes in the syntax for list comprehensions,
- generator expressions, :keyword:`lambda expression and :keyword:`if`
- expressions. For example, this is valid in Python 2.6::
-
- [ x for x in lambda: True, lambda: False if x() ]
+* :keyword:`as` and :keyword:`with` are now reserved words. (Since
+ 2.6, actually.)
- In Python 3.0 you'll have to add parentheses, like this::
-
- [ x for x in (lambda: True, lambda: False) if x() ]
-
-* The *ellipsis* (``...``) can be used as an atomic expression anywhere.
- (Previously it was only allowed in slices.)
+* :keyword:`True`, :keyword:`False`, and :keyword:`None` are reserved
+ words. (2.6 partially enforced the restrictions on :keyword:`None`
+ already.)
+
+* Change from :keyword:`except` *exc*, *var* to
+ :keyword:`except` *exc* :keyword:`as` *var*. See :pep:`3110`.
+
+* List comprehensions no longer support the syntactic form
+ ``[... for var in item1, item2, ...]``. Use
+ ``[... for var in (item1, item2, ...)]`` instead.
+ Also note that list comprehensions have different semantics: they
+ are closer to syntactic sugar for a generator expression inside a
+ :func:`list` constructor, and in particular the loop control
+ variables are no longer leaked into the surrounding scope.
+
+* The *ellipsis* (``...``) can be used as an atomic expression
+ anywhere. (Previously it was only allowed in slices.) Also, it
+ *must* now be spelled as ``...``. (Previously it could also be
+ spelled as ``. . .``, by a mere accident of the grammar.)
Removals
--------
-* Tuple parameter unpacking removed. XXX
+* :pep:`3113`: Tuple parameter unpacking removed. You can no longer
+ write ``def foo(a, (b, c)): ...``.
+ Use ``def foo(a, b_c): b, c = b_c`` instead.
-* Removal of backticks. XXX
+* Removed backticks (use :func:`repr` instead).
-* Removal of ``<>``. Use ``!=`` instead. XXX
+* Removed ``<>`` (use ``!=`` instead).
* Removed keyword: :func:`exec` is no longer a keyword; it remains as
a function. (Fortunately the function syntax was also accepted in
- 2.x.)
+ 2.x.) Also note that :func:`exec` no longer takes a stream argument;
+ instead of ``exec(f)`` you can use ``exec(f.read())``.
* Integer literals no longer support a trailing ``l`` or ``L``.
* String literals no longer support a leading ``u`` or ``U``.
-* The *ellipsis* must now be spelled as ``...``; previously it could
- (by a mere accident of the grammar) also be spelled as ``. . .``.
+* The :keyword:`from` *module* :keyword:`import` ``*`` syntax is only
+ allowed at the module level, no longer inside functions.
+
+* The only acceptable syntax for relative imports is :keyword:`from`
+ ``.``[*module*] :keyword:`import` *name*; :keyword:`import` forms
+ not starting with ``.`` are always interpreted as absolute imports.
+ (:pep:`0328`)
+
Changes Already Present In Python 2.6
=====================================
-This section reminds the reader of new features that were originally
-designed for Python 3.0 but that were already introduced in Python
-2.6. The descriptions in "What's New in Python 2.6" should be
+Since many users presumably make the jump straight from Python 2.5 to
+Python 3.0, this section reminds the reader of new features that were
+originally designed for Python 3.0 but that were back-ported to Python
+2.6. The corresponding sections in :ref:`whats-new-in-2.6` should be
consulted for longer descriptions.
-XXX How to cross-link?
+* :ref:`pep-0343`. The :keyword:`with` statement is now a standard
+ feature and no longer needs to be imported from the ``__future__``.
+ Also check out :ref:`new-26-context-managers` and
+ :ref:`new-module-contextlib`.
+
+* :ref:`pep-0366`. This enhances the usefulness of the :option:`-m`
+ option when the referenced module lives in a package.
+
+* :ref:`pep-0370`.
+
+* :ref:`pep-0371`.
+
+* :ref:`pep-3101`. Note: the 2.6 description mentions the
+ :meth:`format` method for both 8-bit and Unicode strings. In 3.0,
+ only the :class:`str` type (text strings with Unicode support)
+ supports this method; the :class:`bytes` type does not. The plan is
+ to eventually make this the only API for string formatting, and to
+ start deprecating the ``%`` operator in Python 3.1.
+
+* :ref:`pep-3105`. This is now a standard feature and no longer needs
+ to be imported from :mod:`__future__`.
+
+* :ref:`pep-3110`. The :keyword:`except` *exc* :keyword:`as` *var*
+ syntax is now standard and :keyword:`except` *exc*, *var* is no
+ longer supported. (Of course, the :keyword:`as` *var* part is still
+ optional.)
+
+* :ref:`pep-3112`. The ``b"..."`` string literal notation (and its
+ variants like ``b'...'``, ``b"""..."""``, and ``br"..."``) now
+ produces a literal of type :class:`bytes`. More about
+ :class:`bytes` below.
+
+* :ref:`pep-3116`. The :mod:`io` module is now the standard way of
+ doing file I/O, and the initial values of :data:`sys.stdin`,
+ :data:`sys.stdout` and :data:`sys.stderr` are now instances of
+ :class:`io.TextIOBase`. The builtin :func:`open` function is now an
+ alias for :func:`io.open` and has additional keyword arguments
+ *encoding*, *errors*, *newline* and *closefd*. Also note that an
+ invalid *mode* argument now raises :exc:`ValueError`, not
+ :exc:`IOError`.
+
+* :ref:`pep-3118`. The old builtin :func:`buffer` is now really gone;
+ the new builtin :func:`memoryview` provides (mostly) similar
+ functionality.
+
+* :ref:`pep-3119`. The :mod:`abc` module and the ABCs defined in the
+ :mod:`collections` module plays a slightly more prominent role in
+ the language now, and builtin collection types like :class:`dict`
+ and :class:`list` conform to the :class:`collections.MutableMapping`
+ and :class:`collections.MutableSequence` ABC, respectively.
+
+* :ref:`pep-3127`. As mentioned above, the new octal literal
+ notation is the only one supported, and binary literals have been
+ added.
+
+* :ref:`pep-3129`. This speaks for itself.
+
+* :ref:`pep-3141`. The :mod:`numbers` module is another new use of
+ ABCs, defining Python's "numeric tower". Also note the new
+ :mod:`fractions` module.
-* PEP 343: The :keyword:`with` statement is now a standard feature and
- no longer needs to be imported from the ``__future__``.
-* PEP 366: Explicit relative imports from a main module inside a package.
- This enhances the usefulness of the :option:`-m` option.
+Library Changes
+===============
-* PEP 370: Per-user ``site-packages`` directory.
+XXX Brief overview of what's changed in the library.
-* PEP 371: The ``multiprocessing`` package. XXX Did anything change here?
+* :pep:`3108`: stdlib reorganization.
-* PEP 3101: Advanced string formatting. Note: the 2.6 description
- mentions the :method:`format` method for both 8-bit and Unicode
- strings. In 3.0, only the :class:`str` type (text strings with
- Unicode support) supports this method; the :class:`bytes` type does
- not.
+* Killed :mod:`sets`. Use the builtin :func:`set` function.
-* PEP 3105: Print as a function. This is now a standard feature and
- no longer needs to be imported from the ``__future__``.
+* XXX macfs, new, reconvert, stringold, xmllib, pcre, pypcre, strop
-* PEP 3110: Exception-handling changes. The ``except exc as var:``
- syntax is now standard and ``except exc, var:`` is no longer supported.
- (Of course, the ``as var`` part is still optional.)
+* XXX :pep:`4`
-* PEP 3112: Byte literals. The ``b"..."`` string literal notation
- (and its variants like ``b'...'``, ``b"""...""", and ``br'...`'')
- now produces a literal of type :class:`bytes`. More about :class:`bytes`
- below.
+* XXX lib-old: Para, addpack, cmp, cmpcache, codehack, dircmp, dump,
+ find, fmt, grep, lockfile, newdir, ni, packmail, poly, rand,
+ statcache, tb, tzparse, util, whatsound, whrandom, zmod
-* PEP 3116: New I/O library. The :module:`io` module is now the
- standard way of doing file I/O, and the initial values of
- ``sys.stdin``, ``sys.stdout`` and ``sys.stderr`` are now instances
- of :class:`io.TextIOBase`. The builtin :func:`open` function is
- now an alias for ``io.open`` and has additional keyword arguments:
- ``encoding``, ``errors``, ``newline`` and ``closefd``.
+* XXX Removed sys.exitfunc
-* PEP 3118: Revised buffer protocol. The old builtin
- :function:`buffer` is no more; the new builtin
- :function:`memoryview` provides (mostly) similar functionality.
+* XXX Removed sys.exc_clear
-* PEP 3119: Abstract Base Classes (ABCs). These play a slightly more
- prominent role in the language now, and builtin collection types like
- :class:`dict` and :class:`list` conform to the :class:`Mapping` and
- :class:`Sequence` protocol, correspondingly.
+* XXX Removed sys.exc_type, exc_value, exc_traceback. (sys.last_type
+ etc. remain.)
-* PEP 3127: Integer literal suport and syntax. As mentioned above,
- the new octal literal notation is the only one supported, and binary
- literals have been added.
+* XXX array.read, array.write
-* PEP 3129: Class decorators. This speaks for itself.
+* XXX operator.sequenceIncludes
-* PEP 3141: A type hierarchy for numbers. This is another new use of
- ABCs, defining Python's "numeric tower".
+* XXX thread.acquire_lock and thread.release_lock
-* XXX More.
+* XXX UserXXX -> XXXMixin?
+* XXX removed random.jumpahead API
-Library Changes
-===============
+* XXX cookie module revamps
-XXX Brief overview of what's changed in the library.
+* XXX heapq revamp
Strings And Bytes
@@ -411,25 +473,30 @@
* The :class:`basestring` superclass has been removed. The ``2to3`` tool
replaces every occurrence of :class:`basestring` with :class:`str`.
-* PEP 3137: There is a new type, :class:`bytes`, to represent binary data (and
- encoded text, which is treated as binary data until you decide to decode it).
- The :class:`str` and :class:`bytes` types cannot be mixed; you must always
- explicitly convert between them, using the :meth:`str.encode` (str -> bytes)
- or :meth:`bytes.decode` (bytes -> str) methods.
+* :pep:`3137`: There is a new type, :class:`bytes`, to represent
+ binary data (and encoded text, which is treated as binary data until
+ you decide to decode it). The :class:`str` and :class:`bytes` types
+ cannot be mixed; you must always explicitly convert between them,
+ using the :meth:`str.encode` (str -> bytes) or :meth:`bytes.decode`
+ (bytes -> str) methods.
+
+.. XXX add bytearray
* All backslashes in raw strings are interpreted literally. This means that
``'\U'`` and ``'\u'`` escapes in raw strings are not treated specially.
-.. XXX add bytearray
+* :pep:`3138`: :func:`repr` of a string no longer escapes all
+ non-ASCII characters. XXX
-* PEP 3112: Bytes literals, e.g. ``b"abc"``, create :class:`bytes` instances.
+* :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 remains
+* :pep:`3131`: Non-ASCII identifiers. (However, the standard library remains
ASCII-only with the exception of contributor names in 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 Python). Also,
binary files use bytes instead of strings.
@@ -438,8 +505,8 @@
-PEP 3101: A New Approach To String Formatting
-=============================================
+:pep:`3101`: A New Approach To String Formatting
+================================================
* A new system for built-in string formatting operations replaces the
``%`` string formatting operator. (However, the ``%`` operator is
@@ -449,8 +516,8 @@
.. XXX expand this
-PEP 3106: Revamping dict :meth:`dict.keys`, :meth:`dict.items` and :meth:`dict.values`
-======================================================================================
+:pep:`3106`: Revamping dict :meth:`dict.keys`, :meth:`dict.items` and :meth:`dict.values`
+=========================================================================================
.. XXX expand this (but note that the "pitfalls" section currently has
.. XXX more detail :-)
@@ -463,8 +530,8 @@
referred to as *dictionary views*.
-PEP 3107: Function Annotations
-==============================
+:pep:`3107`: Function Annotations
+=================================
.. XXX expand this
@@ -474,7 +541,7 @@
Exception Stuff
===============
-* PEP 352: All exceptions must be derived (directly or indirectly)
+* :pep:`0352`: All exceptions must be derived (directly or indirectly)
from :exc:`BaseException`. This is the root of the exception
hierarchy. Most exceptions should actually be derived from
:exc:`Exception`. This is not a new recommendation, but the
@@ -487,13 +554,13 @@
* Dropping sequence behavior (slicing!) and :attr:`message` attribute of
exception instances.
-* PEP 3109: Raising exceptions. You must now use ``raise Exception(args)``
+* :pep:`3109`: Raising exceptions. You must now use ``raise Exception(args)``
instead of ``raise Exception, args``.
-* PEP 3110: Catching exceptions. You must now use ``except SomeException as
+* :pep:`3110`: Catching exceptions. You must now use ``except SomeException as
identifier:`` instead of ``except Exception, identifier:``
-* PEP 3134: Exception chaining.
+* :pep:`3134`: Exception chaining. XXX
* A few exception messages are improved when Windows fails to load an extension
module. For example, ``error code 193`` is now ``%1 is not a valid Win32
@@ -505,110 +572,105 @@
* Classic classes are gone.
-* PEP 3115: New Metaclass Syntax.
+* :pep:`3115`: New Metaclass Syntax.
-* PEP 3119: Abstract Base Classes (ABCs); ``@abstractmethod`` and
+* :pep:`3119`: Abstract Base Classes (ABCs); ``@abstractmethod`` and
``@abstractproperty`` decorators; collection ABCs.
-* PEP 3129: Class decorators.
+* :pep:`3129`: Class decorators.
-* PEP 3141: Numeric ABCs.
+* :pep:`3141`: Numeric ABCs.
Other Language Changes
======================
-Here are most of the changes that Python 3.0 makes to the core Python
-language and built-in functions.
-
-* Removed backticks (use :func:`repr` instead).
-
-* Removed ``<>`` (use ``!=`` instead).
+* Moved :func:`intern` to :func:`sys.intern`.
* ``!=`` now returns the opposite of ``==``, unless ``==`` returns
``NotImplemented``.
-* :keyword:`as` and :keyword:`with` are keywords.
-
-* ``True``, ``False``, and ``None`` are keywords.
-
-* PEP 237: :class:`long` renamed to :class:`int`. That is, there is only one
- built-in integral type, named :class:`int`; but it behaves like the old
- :class:`long` type, with the exception that the literal suffix ``L`` is
- neither supported by the parser nor produced by :func:`repr` anymore.
- :data:`sys.maxint` was also removed since the int type has no maximum value
- anymore. Use :data:`sys.maxsize` instead.
- XXX Is this a dupe from the intro section on integers?
-
-* PEP 238: int division returns a float.
-
-* The ordering operators behave differently: for example, ``x < y`` where ``x``
- and ``y`` have incompatible types raises :exc:`TypeError` instead of returning
- a pseudo-random boolean.
-
-* :meth:`__getslice__` and friends killed. The syntax ``a[i:j]`` now translates
- to ``a.__getitem__(slice(i, j))`` (or :meth:`__setitem__` or
- :meth:`__delitem__`, depending on context).
-
-* PEP 3102: Keyword-only arguments. Named parameters occurring after ``*args``
- in the parameter list *must* be specified using keyword syntax in the call.
- You can also use a bare ``*`` in the parameter list to indicate that you don't
- accept a variable-length argument list, but you do have keyword-only
- arguments.
-
-* PEP 3104: :keyword:`nonlocal` statement. Using ``nonlocal x`` you can now
- assign directly to a variable in an outer (but non-global) scope.
-
-* PEP 3111: :func:`raw_input` renamed to :func:`input`. That is, the new
- :func:`input` function reads a line from :data:`sys.stdin` and returns it with
- the trailing newline stripped. It raises :exc:`EOFError` if the input is
- terminated prematurely. To get the old behavior of :func:`input`, use
- ``eval(input())``.
-
-* :func:`xrange` renamed to :func:`range`, so :func:`range` will no longer
- produce a list but an iterable yielding integers when iterated over.
-
-* PEP 3113: Tuple parameter unpacking removed. You can no longer write ``def
- foo(a, (b, c)): ...``. Use ``def foo(a, b_c): b, c = b_c`` instead.
-
-* PEP 3114: ``.next()`` renamed to :meth:`__next__`, new builtin :func:`next` to
- call the :meth:`__next__` method on an object.
-
-* PEP 3127: New octal literals; binary literals and :func:`bin`. Instead of
- ``0666``, you write ``0o666``. The :func:`oct` function is modified
- accordingly. Also, ``0b1010`` equals 10, and ``bin(10)`` returns
- ``"0b1010"``. ``0666`` is now a :exc:`SyntaxError`.
-
-* PEP 3132: Extended Iterable Unpacking. You can now write things like ``a, b,
- *rest = some_sequence``. And even ``*rest, a = stuff``. The ``rest`` object
- is always a list; the right-hand side may be any iterable.
-
-* PEP 3135: New :func:`super`. You can now invoke :func:`super` without
- arguments and the right class and instance will automatically be chosen. With
- arguments, its behavior is unchanged.
+* The concept of "unbound methods" was removed from the language.
+ When referencing a method as a class attribute, you now get a plain
+ function object.
+
+* :meth:`__getslice__`, :meth:`__setslice__` and :meth:`__delslice__`
+ were killed. The syntax ``a[i:j]`` now translates to
+ ``a.__getitem__(slice(i, j))`` (or :meth:`__setitem__` or
+ :meth:`__delitem__`, when used as an assignment or deletion target,
+ respectively).
+
+* :pep:`3111`: :func:`raw_input` renamed to :func:`input`. That is,
+ the new :func:`input` function reads a line from :data:`sys.stdin`
+ and returns it with the trailing newline stripped. It raises
+ :exc:`EOFError` if the input is terminated prematurely. To get the
+ old behavior of :func:`input`, use ``eval(input())``.
+
+* :func:`xrange` renamed to :func:`range`, so :func:`range` will no
+ longer produce a list but an iterable yielding integers when
+ iterated over. XXX dupe
+
+* :pep:`3114`: ``.next()`` renamed to :meth:`__next__`, new builtin
+ :func:`next` to call the :meth:`__next__` method on an object.
+
+* :pep:`3135`: New :func:`super`. You can now invoke :func:`super`
+ without arguments and the right class and instance will
+ automatically be chosen. With arguments, its behavior is unchanged.
* :func:`zip`, :func:`map` and :func:`filter` return iterators.
* :data:`string.letters` and its friends (:data:`string.lowercase` and
- :data:`string.uppercase`) are gone. Use :data:`string.ascii_letters`
- etc. instead.
+ :data:`string.uppercase`) are gone. Use
+ :data:`string.ascii_letters` etc. instead. (The reason for the
+ removal is that :data:string.letters` and friends had
+ locale-specific behavior, which is a bad idea for such
+ attractively-named global "constants".)
+
+* Removed: :func:`apply`. Instead of ``apply(f, args)`` use
+ ``f(*args)``.
+
+* Removed :func:`callable`. Instead of ``callable(f)`` you can use
+ ``hasattr(f, '__call__')``. The :func:`operator.isCallable` function
+ is also gone.
+
+* Removed :func:`coerce`. This function no longer serves a purpose
+ now that classic classes are gone.
+
+* Removed :func:`execfile`. Instead of ``execfile(fn)`` use
+ ``exec(open(fn).read())``.
-* Removed: :func:`apply`, :func:`callable`, :func:`coerce`, :func:`execfile`,
- :func:`file`, :func:`reduce`, :func:`reload`.
+* Removed :class:`file`. Use :func:`open`.
-* Removed: :meth:`dict.has_key` -- use the ``in`` operator instead.
+* Removed :func:`reduce`. Use :func:`functools.reduce` if you really
+ need it; however, 99 percent of the time an explicit :keyword:`for`
+ loop is more readable.
-* :func:`exec` is now a function.
+* Removed :func:`reload`. Use :func:`imp.reload`.
-* The :meth:`__oct__` and :meth:`__hex__` special methods are removed --
- :func:`oct` and :func:`hex` use :meth:`__index__` now to convert the argument
- to an integer.
+* Removed. :meth:`dict.has_key` -- use the :keyword:`in` operator
+ instead.
-* Support is removed for :attr:`__members__` and :attr:`__methods__`.
+* The :meth:`__oct__` and :meth:`__hex__` special methods are removed
+ -- :func:`oct` and :func:`hex` use :meth:`__index__` now to convert
+ the argument to an integer.
-* Renamed the boolean conversion C-level slot and method: ``nb_nonzero`` is now
- ``nb_bool`` and :meth:`__nonzero__` is now :meth:`__bool__`.
+* Removed support for :attr:`__members__` and :attr:`__methods__`.
+* Renamed the boolean conversion C-level slot and method:
+ ``nb_nonzero`` is now ``nb_bool`` and :meth:`__nonzero__` is now
+ :meth:`__bool__`.
+
+* Renamed module :mod:`__builtin__` to :mod:`builtins` (removing the
+ underscores, adding an 's'). The :data:`__builtins__` variable
+ found in most global namespaces is unchanged. To modify a builtin,
+ you should use :mod:`builtins`, not :data:`__builtins__`!
+
+* Renamed function attributes :attr:`func_whatever` to
+ :attr:`__whatever__`. XXX list every single one.
+
+* Removed :exc:`StandardError`.
+
+* Removed METH_OLDARGS and WITH_CYCLE_GC. XXX more.
.. ======================================================================
@@ -616,11 +678,11 @@
Optimizations
-------------
-* Detailed changes are listed here.
-
The net result of the 3.0 generalizations is that Python 3.0 runs the
-pystone benchmark around a third slower than Python 2.5. There's room
-for improvement, but it will happen after 3.0 is released!
+pystone benchmark around 10% slower than Python 2.5. Most likely the
+biggest cause is the removal of special-casing for small integers.
+There's room for improvement, but it will happen after 3.0 is
+released!
.. ======================================================================
@@ -668,11 +730,11 @@
Changes to Python's build process and to the C API include:
-* PEP 3118: New Buffer API.
+* :pep:`3118`: New Buffer API. XXX
-* PEP 3121: Extension Module Initialization & Finalization.
+* :pep:`3121`: Extension Module Initialization & Finalization. XXX
-* PEP 3123: Making :cmacro:`PyObject_HEAD` conform to standard C.
+* :pep:`3123`: Making :cmacro:`PyObject_HEAD` conform to standard C. XXX
* No more C API support for restricted execution.
@@ -689,8 +751,9 @@
Port-Specific Changes
---------------------
-Platform-specific changes go here.
+XXX Platform-specific changes go here.
+* XXX BeOS, RISCOS, Irix, Tru64 support
.. ======================================================================
@@ -705,9 +768,9 @@
logs finds there were XXX patches applied and YYY bugs fixed between
Python 2.6 and 3.0. Both figures are likely to be underestimates.
-Some of the more notable changes are:
+XXX Some of the more notable changes are:
-* Details go here.
+* XXX Details go here.
.. ======================================================================
Date: Tue Dec 2 23:34:15 2008
New Revision: 67479
Log:
Another checkpoint. More XXXes added...
Also add some labels to 2.6.rst and howto/unicode.rst so I can refer
to them. (Somehow a label named 'module-contextlib' couldn't be
referenced -- why???)
Modified:
python/branches/py3k/Doc/howto/unicode.rst
python/branches/py3k/Doc/whatsnew/2.6.rst
python/branches/py3k/Doc/whatsnew/3.0.rst
Modified: python/branches/py3k/Doc/howto/unicode.rst
==============================================================================
--- python/branches/py3k/Doc/howto/unicode.rst (original)
+++ python/branches/py3k/Doc/howto/unicode.rst Tue Dec 2 23:34:15 2008
@@ -1,3 +1,5 @@
+.. _unicode-howto:
+
*****************
Unicode HOWTO
*****************
Modified: python/branches/py3k/Doc/whatsnew/2.6.rst
==============================================================================
--- python/branches/py3k/Doc/whatsnew/2.6.rst (original)
+++ python/branches/py3k/Doc/whatsnew/2.6.rst Tue Dec 2 23:34:15 2008
@@ -1,3 +1,5 @@
+.. _whats-new-in-2.6:
+
****************************
What's New in Python 2.6
****************************
@@ -244,6 +246,8 @@
The underlying reStructuredText parser and toolset.
+.. _pep-0343:
+
PEP 343: The 'with' statement
=============================
@@ -424,7 +428,7 @@
# return False
-.. _module-contextlib:
+.. _new-module-contextlib:
The contextlib module
---------------------
Modified: python/branches/py3k/Doc/whatsnew/3.0.rst
==============================================================================
--- python/branches/py3k/Doc/whatsnew/3.0.rst (original)
+++ python/branches/py3k/Doc/whatsnew/3.0.rst Tue Dec 2 23:34:15 2008
@@ -2,9 +2,9 @@
What's New In Python 3.0
****************************
-.. XXX add trademark info for Apple, Microsoft, SourceForge.
+.. XXX Add trademark info for Apple, Microsoft.
-.. XXX turn all PEP references into :pep:`NNN` markup.
+.. XXX Remove duplicates; just put info in the most relevant section.
:Author: Guido van Rossum
:Release: |release|
@@ -53,11 +53,12 @@
when researching a change.
This article explains the new features in Python 3.0, compared to 2.6.
-Python 3.0 is the first ever *intentionally incompatible* release.
-There are more changes than in a typical release, and more that are
-important for all Python users. Nevertheless, after digesting the
-changes, you'll find that Python really hasn't changed all that much
--- by and large, we're merely fixing well-known annoyances and warts.
+Python 3.0, also known as "Python 3000" or "Py3k", is the first ever
+*intentionally incompatible* release. There are more changes than in
+a typical release, and more that are important for all Python users.
+Nevertheless, after digesting the changes, you'll find that Python
+really hasn't changed all that much -- by and large, we're merely
+fixing well-known annoyances and warts.
This article doesn't attempt to provide a complete specification of
the new features, but instead provides a convenient overview. For
@@ -79,16 +80,15 @@
Common Stumbling Blocks
=======================
-This section briefly lists a few changes that are more likely to trip
-people up, without necessarily raising obvious errors. Most issues
-are explained in more detail in later sections.
+This section lists those few changes that are most likely to trip you
+up if you're used to Python 2.5.
Print Is A Function
-------------------
-The ``print`` statement has been replaced with a :func:`print` function,
-with keyword arguments to replace most of the special syntax of the
-old ``print`` statement (PEP 3105). Examples::
+The :keyword:`print` statement has been replaced with a :func:`print`
+function, with keyword arguments to replace most of the special syntax
+of the old :keyword:`print` statement (:pep:`3105`). Examples::
Old: print "The answer is", 2*2
New: print("The answer is", 2*2)
@@ -116,7 +116,7 @@
Note:
* The :func:`print` function doesn't support the "softspace" feature of
- the old ``print`` statement. For example, in Python 2.x,
+ the old :keyword:`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")`` writes ``"A\n B\n"``.
@@ -125,14 +125,16 @@
``print(x)`` instead!
* When using the ``2to3`` source-to-source conversion tool, all
- ``print`` statements are automatically converted to :func:`print`
- function calls, so this is mostly a non-issue for larger projects.
+ :keyword:`print` statements are automatically converted to
+ :func:`print` function calls, so this is mostly a non-issue for
+ larger projects.
Text Strings Vs. Bytes
----------------------
Everything you thought you knew about binary data and Unicode has
-changed:
+changed. There's a longer section below; here's a summary of the
+changes:
* Python 3.0 uses *strings* and *bytes* instead of *Unicode strings*
and *8-bit strings*. The difference is that any attempt to mix
@@ -157,10 +159,12 @@
reading or writing more than pure ASCII text should probably have a
way to override the encoding.
-* XXX More below?
+* The builtin :class:`basestring` abstract type was removed. Use
+ :class:`str` instead. The :class:`str` and :class:`bytes` types
+ don't have functionality enough in common to warrant a shared base
+ class.
-* See also the *Unicode HOWTO*. (XXX How to make this a link?)
- (XXX Move to longer section below?)
+* See also the :ref:`unicode-howto`, which was updated for Python 3.0.
Views And Interators Instead Of Lists
-------------------------------------
@@ -219,15 +223,13 @@
Integers
--------
-* We unified the :class:`int` and :class:`long` types. All integers
- are now of type :class:`int`.
-
-* ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior.
- (The latter syntax has existed for years, at least since Python 2.2.)
+* :pep:`0237`: :class:`long` renamed to :class:`int`. That is, there
+ is only one built-in integral type, named :class:`int`; but it
+ behaves mostly like the old :class:`long` type.
* The :func:`repr` of a long integer doesn't include the trailing ``L``
anymore, so code that unconditionally strips that character will
- chop off the last digit instead.
+ chop off the last digit instead. (Use :func:`str` instead.)
* The :data:`sys.maxint` constant was removed, since there is no
longer a limit to the value of ints. However, :data:`sys.maxsize`
@@ -236,7 +238,9 @@
and is typically the same as :data:`sys.maxint` in previous releases
on the same platform (assuming the same build options).
-* XXX More below?
+* ``1/2`` returns a float. Use ``1//2`` to get the truncating behavior.
+ (The latter syntax has existed for years, at least since Python 2.2.)
+ See :pep:`0238`.
Overview Of Syntactic Changes
@@ -245,35 +249,42 @@
This section gives a brief overview of every *syntactic* change.
Several of these are discussed at greater length later.
-XXX Did I get everything?
-
Additions
---------
* Function argument and return value annotations (see below). XXX
-* A lone ``*`` in a formal parameter list implies that any following
- arguments *must* be specified in keyword form. (XXX Didn't this make
- it into 2.6 as well?)
+* :pep:`3102`: Keyword-only arguments. Named parameters occurring
+ after ``*args`` in the parameter list *must* be specified using
+ keyword syntax in the call. You can also use a bare ``*`` in the
+ parameter list to indicate that you don't accept a variable-length
+ argument list, but you do have keyword-only arguments.
* Keyword arguments are allowed after the list of base classes in a
class definition. This is used by the new convention for specifying
a metaclass, but can be used for other purposes as well, as long as
the metaclass supports it.
-* Tuple-unpacking assignment now has a *wildcard* syntax, e.g.::
+* :pep:`3104`: :keyword:`nonlocal` statement. Using ``nonlocal x``
+ you can now assign directly to a variable in an outer (but
+ non-global) scope. :keyword:`nonlocal` is a new reserved word.
+
+* :pep:`3132`: Extended Iterable Unpacking. You can now write things
+ like ``a, b, *rest = some_sequence``. And even ``*rest, a =
+ stuff``. The ``rest`` object is always a (possibly empty) list; the
+ right-hand side may be any iterable. Example::
- (a, b, *rest) = range(5)
+ (a, *rest, b) = range(5)
- This sets *a* to 0, *b* to 1, and \*rest to ``[2, 3, 4]``.
+ This sets *a* to ``0``, *b* to ``4``, and \*rest to ``[1, 2, 3]``.
* Dictionary comprehensions: ``{k: v for k, v in stuff}`` means the
same thing as ``dict(stuff)`` but is more flexible.
* Set literals, e.g. ``{1, 2}``. Note that ``{}`` is an empty
- dictionary; use ``set()`` for an empty set. Set comprehensions
- are also supported; ``{x for x in stuff}`` means the same thing
- as ``set(stuff)`` but is more flexible.
+ dictionary; use ``set()`` for an empty set. Set comprehensions are
+ also supported; ``{x for x in stuff}`` means the same thing as
+ ``set(stuff)`` but is more flexible.
* New octal literals, e.g. ``0o720`` (already in 2.6). The old octal
literals (``0720``) are gone.
@@ -286,118 +297,169 @@
-------
* New :keyword:`raise` statement syntax: ``raise [expr [from expr]]``.
+ Also note that string exceptions are no longer legal (:pep:`0352`).
-* New keywords: :keyword:`as`, :keyword:`with` (already in 2.6),
- :keyword:`None` (partially enforced in 2.6), :keyword:`True`,
- :keyword:`False` (these were built-ins previously), and
- :keyword:`nonlocal` (for the new ``nonlocal`` statement).
-
-* Change from ``except exc, var:`` to ``except exc as var:``. XXX
-
-* *Very* subtle changes in the syntax for list comprehensions,
- generator expressions, :keyword:`lambda expression and :keyword:`if`
- expressions. For example, this is valid in Python 2.6::
-
- [ x for x in lambda: True, lambda: False if x() ]
+* :keyword:`as` and :keyword:`with` are now reserved words. (Since
+ 2.6, actually.)
- In Python 3.0 you'll have to add parentheses, like this::
-
- [ x for x in (lambda: True, lambda: False) if x() ]
-
-* The *ellipsis* (``...``) can be used as an atomic expression anywhere.
- (Previously it was only allowed in slices.)
+* :keyword:`True`, :keyword:`False`, and :keyword:`None` are reserved
+ words. (2.6 partially enforced the restrictions on :keyword:`None`
+ already.)
+
+* Change from :keyword:`except` *exc*, *var* to
+ :keyword:`except` *exc* :keyword:`as` *var*. See :pep:`3110`.
+
+* List comprehensions no longer support the syntactic form
+ ``[... for var in item1, item2, ...]``. Use
+ ``[... for var in (item1, item2, ...)]`` instead.
+ Also note that list comprehensions have different semantics: they
+ are closer to syntactic sugar for a generator expression inside a
+ :func:`list` constructor, and in particular the loop control
+ variables are no longer leaked into the surrounding scope.
+
+* The *ellipsis* (``...``) can be used as an atomic expression
+ anywhere. (Previously it was only allowed in slices.) Also, it
+ *must* now be spelled as ``...``. (Previously it could also be
+ spelled as ``. . .``, by a mere accident of the grammar.)
Removals
--------
-* Tuple parameter unpacking removed. XXX
+* :pep:`3113`: Tuple parameter unpacking removed. You can no longer
+ write ``def foo(a, (b, c)): ...``.
+ Use ``def foo(a, b_c): b, c = b_c`` instead.
-* Removal of backticks. XXX
+* Removed backticks (use :func:`repr` instead).
-* Removal of ``<>``. Use ``!=`` instead. XXX
+* Removed ``<>`` (use ``!=`` instead).
* Removed keyword: :func:`exec` is no longer a keyword; it remains as
a function. (Fortunately the function syntax was also accepted in
- 2.x.)
+ 2.x.) Also note that :func:`exec` no longer takes a stream argument;
+ instead of ``exec(f)`` you can use ``exec(f.read())``.
* Integer literals no longer support a trailing ``l`` or ``L``.
* String literals no longer support a leading ``u`` or ``U``.
-* The *ellipsis* must now be spelled as ``...``; previously it could
- (by a mere accident of the grammar) also be spelled as ``. . .``.
+* The :keyword:`from` *module* :keyword:`import` ``*`` syntax is only
+ allowed at the module level, no longer inside functions.
+
+* The only acceptable syntax for relative imports is :keyword:`from`
+ ``.``[*module*] :keyword:`import` *name*; :keyword:`import` forms
+ not starting with ``.`` are always interpreted as absolute imports.
+ (:pep:`0328`)
+
Changes Already Present In Python 2.6
=====================================
-This section reminds the reader of new features that were originally
-designed for Python 3.0 but that were already introduced in Python
-2.6. The descriptions in "What's New in Python 2.6" should be
+Since many users presumably make the jump straight from Python 2.5 to
+Python 3.0, this section reminds the reader of new features that were
+originally designed for Python 3.0 but that were back-ported to Python
+2.6. The corresponding sections in :ref:`whats-new-in-2.6` should be
consulted for longer descriptions.
-XXX How to cross-link?
+* :ref:`pep-0343`. The :keyword:`with` statement is now a standard
+ feature and no longer needs to be imported from the ``__future__``.
+ Also check out :ref:`new-26-context-managers` and
+ :ref:`new-module-contextlib`.
+
+* :ref:`pep-0366`. This enhances the usefulness of the :option:`-m`
+ option when the referenced module lives in a package.
+
+* :ref:`pep-0370`.
+
+* :ref:`pep-0371`.
+
+* :ref:`pep-3101`. Note: the 2.6 description mentions the
+ :meth:`format` method for both 8-bit and Unicode strings. In 3.0,
+ only the :class:`str` type (text strings with Unicode support)
+ supports this method; the :class:`bytes` type does not. The plan is
+ to eventually make this the only API for string formatting, and to
+ start deprecating the ``%`` operator in Python 3.1.
+
+* :ref:`pep-3105`. This is now a standard feature and no longer needs
+ to be imported from :mod:`__future__`.
+
+* :ref:`pep-3110`. The :keyword:`except` *exc* :keyword:`as` *var*
+ syntax is now standard and :keyword:`except` *exc*, *var* is no
+ longer supported. (Of course, the :keyword:`as` *var* part is still
+ optional.)
+
+* :ref:`pep-3112`. The ``b"..."`` string literal notation (and its
+ variants like ``b'...'``, ``b"""..."""``, and ``br"..."``) now
+ produces a literal of type :class:`bytes`. More about
+ :class:`bytes` below.
+
+* :ref:`pep-3116`. The :mod:`io` module is now the standard way of
+ doing file I/O, and the initial values of :data:`sys.stdin`,
+ :data:`sys.stdout` and :data:`sys.stderr` are now instances of
+ :class:`io.TextIOBase`. The builtin :func:`open` function is now an
+ alias for :func:`io.open` and has additional keyword arguments
+ *encoding*, *errors*, *newline* and *closefd*. Also note that an
+ invalid *mode* argument now raises :exc:`ValueError`, not
+ :exc:`IOError`.
+
+* :ref:`pep-3118`. The old builtin :func:`buffer` is now really gone;
+ the new builtin :func:`memoryview` provides (mostly) similar
+ functionality.
+
+* :ref:`pep-3119`. The :mod:`abc` module and the ABCs defined in the
+ :mod:`collections` module plays a slightly more prominent role in
+ the language now, and builtin collection types like :class:`dict`
+ and :class:`list` conform to the :class:`collections.MutableMapping`
+ and :class:`collections.MutableSequence` ABC, respectively.
+
+* :ref:`pep-3127`. As mentioned above, the new octal literal
+ notation is the only one supported, and binary literals have been
+ added.
+
+* :ref:`pep-3129`. This speaks for itself.
+
+* :ref:`pep-3141`. The :mod:`numbers` module is another new use of
+ ABCs, defining Python's "numeric tower". Also note the new
+ :mod:`fractions` module.
-* PEP 343: The :keyword:`with` statement is now a standard feature and
- no longer needs to be imported from the ``__future__``.
-* PEP 366: Explicit relative imports from a main module inside a package.
- This enhances the usefulness of the :option:`-m` option.
+Library Changes
+===============
-* PEP 370: Per-user ``site-packages`` directory.
+XXX Brief overview of what's changed in the library.
-* PEP 371: The ``multiprocessing`` package. XXX Did anything change here?
+* :pep:`3108`: stdlib reorganization.
-* PEP 3101: Advanced string formatting. Note: the 2.6 description
- mentions the :method:`format` method for both 8-bit and Unicode
- strings. In 3.0, only the :class:`str` type (text strings with
- Unicode support) supports this method; the :class:`bytes` type does
- not.
+* Killed :mod:`sets`. Use the builtin :func:`set` function.
-* PEP 3105: Print as a function. This is now a standard feature and
- no longer needs to be imported from the ``__future__``.
+* XXX macfs, new, reconvert, stringold, xmllib, pcre, pypcre, strop
-* PEP 3110: Exception-handling changes. The ``except exc as var:``
- syntax is now standard and ``except exc, var:`` is no longer supported.
- (Of course, the ``as var`` part is still optional.)
+* XXX :pep:`4`
-* PEP 3112: Byte literals. The ``b"..."`` string literal notation
- (and its variants like ``b'...'``, ``b"""...""", and ``br'...`'')
- now produces a literal of type :class:`bytes`. More about :class:`bytes`
- below.
+* XXX lib-old: Para, addpack, cmp, cmpcache, codehack, dircmp, dump,
+ find, fmt, grep, lockfile, newdir, ni, packmail, poly, rand,
+ statcache, tb, tzparse, util, whatsound, whrandom, zmod
-* PEP 3116: New I/O library. The :module:`io` module is now the
- standard way of doing file I/O, and the initial values of
- ``sys.stdin``, ``sys.stdout`` and ``sys.stderr`` are now instances
- of :class:`io.TextIOBase`. The builtin :func:`open` function is
- now an alias for ``io.open`` and has additional keyword arguments:
- ``encoding``, ``errors``, ``newline`` and ``closefd``.
+* XXX Removed sys.exitfunc
-* PEP 3118: Revised buffer protocol. The old builtin
- :function:`buffer` is no more; the new builtin
- :function:`memoryview` provides (mostly) similar functionality.
+* XXX Removed sys.exc_clear
-* PEP 3119: Abstract Base Classes (ABCs). These play a slightly more
- prominent role in the language now, and builtin collection types like
- :class:`dict` and :class:`list` conform to the :class:`Mapping` and
- :class:`Sequence` protocol, correspondingly.
+* XXX Removed sys.exc_type, exc_value, exc_traceback. (sys.last_type
+ etc. remain.)
-* PEP 3127: Integer literal suport and syntax. As mentioned above,
- the new octal literal notation is the only one supported, and binary
- literals have been added.
+* XXX array.read, array.write
-* PEP 3129: Class decorators. This speaks for itself.
+* XXX operator.sequenceIncludes
-* PEP 3141: A type hierarchy for numbers. This is another new use of
- ABCs, defining Python's "numeric tower".
+* XXX thread.acquire_lock and thread.release_lock
-* XXX More.
+* XXX UserXXX -> XXXMixin?
+* XXX removed random.jumpahead API
-Library Changes
-===============
+* XXX cookie module revamps
-XXX Brief overview of what's changed in the library.
+* XXX heapq revamp
Strings And Bytes
@@ -411,25 +473,30 @@
* The :class:`basestring` superclass has been removed. The ``2to3`` tool
replaces every occurrence of :class:`basestring` with :class:`str`.
-* PEP 3137: There is a new type, :class:`bytes`, to represent binary data (and
- encoded text, which is treated as binary data until you decide to decode it).
- The :class:`str` and :class:`bytes` types cannot be mixed; you must always
- explicitly convert between them, using the :meth:`str.encode` (str -> bytes)
- or :meth:`bytes.decode` (bytes -> str) methods.
+* :pep:`3137`: There is a new type, :class:`bytes`, to represent
+ binary data (and encoded text, which is treated as binary data until
+ you decide to decode it). The :class:`str` and :class:`bytes` types
+ cannot be mixed; you must always explicitly convert between them,
+ using the :meth:`str.encode` (str -> bytes) or :meth:`bytes.decode`
+ (bytes -> str) methods.
+
+.. XXX add bytearray
* All backslashes in raw strings are interpreted literally. This means that
``'\U'`` and ``'\u'`` escapes in raw strings are not treated specially.
-.. XXX add bytearray
+* :pep:`3138`: :func:`repr` of a string no longer escapes all
+ non-ASCII characters. XXX
-* PEP 3112: Bytes literals, e.g. ``b"abc"``, create :class:`bytes` instances.
+* :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 remains
+* :pep:`3131`: Non-ASCII identifiers. (However, the standard library remains
ASCII-only with the exception of contributor names in 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 Python). Also,
binary files use bytes instead of strings.
@@ -438,8 +505,8 @@
-PEP 3101: A New Approach To String Formatting
-=============================================
+:pep:`3101`: A New Approach To String Formatting
+================================================
* A new system for built-in string formatting operations replaces the
``%`` string formatting operator. (However, the ``%`` operator is
@@ -449,8 +516,8 @@
.. XXX expand this
-PEP 3106: Revamping dict :meth:`dict.keys`, :meth:`dict.items` and :meth:`dict.values`
-======================================================================================
+:pep:`3106`: Revamping dict :meth:`dict.keys`, :meth:`dict.items` and :meth:`dict.values`
+=========================================================================================
.. XXX expand this (but note that the "pitfalls" section currently has
.. XXX more detail :-)
@@ -463,8 +530,8 @@
referred to as *dictionary views*.
-PEP 3107: Function Annotations
-==============================
+:pep:`3107`: Function Annotations
+=================================
.. XXX expand this
@@ -474,7 +541,7 @@
Exception Stuff
===============
-* PEP 352: All exceptions must be derived (directly or indirectly)
+* :pep:`0352`: All exceptions must be derived (directly or indirectly)
from :exc:`BaseException`. This is the root of the exception
hierarchy. Most exceptions should actually be derived from
:exc:`Exception`. This is not a new recommendation, but the
@@ -487,13 +554,13 @@
* Dropping sequence behavior (slicing!) and :attr:`message` attribute of
exception instances.
-* PEP 3109: Raising exceptions. You must now use ``raise Exception(args)``
+* :pep:`3109`: Raising exceptions. You must now use ``raise Exception(args)``
instead of ``raise Exception, args``.
-* PEP 3110: Catching exceptions. You must now use ``except SomeException as
+* :pep:`3110`: Catching exceptions. You must now use ``except SomeException as
identifier:`` instead of ``except Exception, identifier:``
-* PEP 3134: Exception chaining.
+* :pep:`3134`: Exception chaining. XXX
* A few exception messages are improved when Windows fails to load an extension
module. For example, ``error code 193`` is now ``%1 is not a valid Win32
@@ -505,110 +572,105 @@
* Classic classes are gone.
-* PEP 3115: New Metaclass Syntax.
+* :pep:`3115`: New Metaclass Syntax.
-* PEP 3119: Abstract Base Classes (ABCs); ``@abstractmethod`` and
+* :pep:`3119`: Abstract Base Classes (ABCs); ``@abstractmethod`` and
``@abstractproperty`` decorators; collection ABCs.
-* PEP 3129: Class decorators.
+* :pep:`3129`: Class decorators.
-* PEP 3141: Numeric ABCs.
+* :pep:`3141`: Numeric ABCs.
Other Language Changes
======================
-Here are most of the changes that Python 3.0 makes to the core Python
-language and built-in functions.
-
-* Removed backticks (use :func:`repr` instead).
-
-* Removed ``<>`` (use ``!=`` instead).
+* Moved :func:`intern` to :func:`sys.intern`.
* ``!=`` now returns the opposite of ``==``, unless ``==`` returns
``NotImplemented``.
-* :keyword:`as` and :keyword:`with` are keywords.
-
-* ``True``, ``False``, and ``None`` are keywords.
-
-* PEP 237: :class:`long` renamed to :class:`int`. That is, there is only one
- built-in integral type, named :class:`int`; but it behaves like the old
- :class:`long` type, with the exception that the literal suffix ``L`` is
- neither supported by the parser nor produced by :func:`repr` anymore.
- :data:`sys.maxint` was also removed since the int type has no maximum value
- anymore. Use :data:`sys.maxsize` instead.
- XXX Is this a dupe from the intro section on integers?
-
-* PEP 238: int division returns a float.
-
-* The ordering operators behave differently: for example, ``x < y`` where ``x``
- and ``y`` have incompatible types raises :exc:`TypeError` instead of returning
- a pseudo-random boolean.
-
-* :meth:`__getslice__` and friends killed. The syntax ``a[i:j]`` now translates
- to ``a.__getitem__(slice(i, j))`` (or :meth:`__setitem__` or
- :meth:`__delitem__`, depending on context).
-
-* PEP 3102: Keyword-only arguments. Named parameters occurring after ``*args``
- in the parameter list *must* be specified using keyword syntax in the call.
- You can also use a bare ``*`` in the parameter list to indicate that you don't
- accept a variable-length argument list, but you do have keyword-only
- arguments.
-
-* PEP 3104: :keyword:`nonlocal` statement. Using ``nonlocal x`` you can now
- assign directly to a variable in an outer (but non-global) scope.
-
-* PEP 3111: :func:`raw_input` renamed to :func:`input`. That is, the new
- :func:`input` function reads a line from :data:`sys.stdin` and returns it with
- the trailing newline stripped. It raises :exc:`EOFError` if the input is
- terminated prematurely. To get the old behavior of :func:`input`, use
- ``eval(input())``.
-
-* :func:`xrange` renamed to :func:`range`, so :func:`range` will no longer
- produce a list but an iterable yielding integers when iterated over.
-
-* PEP 3113: Tuple parameter unpacking removed. You can no longer write ``def
- foo(a, (b, c)): ...``. Use ``def foo(a, b_c): b, c = b_c`` instead.
-
-* PEP 3114: ``.next()`` renamed to :meth:`__next__`, new builtin :func:`next` to
- call the :meth:`__next__` method on an object.
-
-* PEP 3127: New octal literals; binary literals and :func:`bin`. Instead of
- ``0666``, you write ``0o666``. The :func:`oct` function is modified
- accordingly. Also, ``0b1010`` equals 10, and ``bin(10)`` returns
- ``"0b1010"``. ``0666`` is now a :exc:`SyntaxError`.
-
-* PEP 3132: Extended Iterable Unpacking. You can now write things like ``a, b,
- *rest = some_sequence``. And even ``*rest, a = stuff``. The ``rest`` object
- is always a list; the right-hand side may be any iterable.
-
-* PEP 3135: New :func:`super`. You can now invoke :func:`super` without
- arguments and the right class and instance will automatically be chosen. With
- arguments, its behavior is unchanged.
+* The concept of "unbound methods" was removed from the language.
+ When referencing a method as a class attribute, you now get a plain
+ function object.
+
+* :meth:`__getslice__`, :meth:`__setslice__` and :meth:`__delslice__`
+ were killed. The syntax ``a[i:j]`` now translates to
+ ``a.__getitem__(slice(i, j))`` (or :meth:`__setitem__` or
+ :meth:`__delitem__`, when used as an assignment or deletion target,
+ respectively).
+
+* :pep:`3111`: :func:`raw_input` renamed to :func:`input`. That is,
+ the new :func:`input` function reads a line from :data:`sys.stdin`
+ and returns it with the trailing newline stripped. It raises
+ :exc:`EOFError` if the input is terminated prematurely. To get the
+ old behavior of :func:`input`, use ``eval(input())``.
+
+* :func:`xrange` renamed to :func:`range`, so :func:`range` will no
+ longer produce a list but an iterable yielding integers when
+ iterated over. XXX dupe
+
+* :pep:`3114`: ``.next()`` renamed to :meth:`__next__`, new builtin
+ :func:`next` to call the :meth:`__next__` method on an object.
+
+* :pep:`3135`: New :func:`super`. You can now invoke :func:`super`
+ without arguments and the right class and instance will
+ automatically be chosen. With arguments, its behavior is unchanged.
* :func:`zip`, :func:`map` and :func:`filter` return iterators.
* :data:`string.letters` and its friends (:data:`string.lowercase` and
- :data:`string.uppercase`) are gone. Use :data:`string.ascii_letters`
- etc. instead.
+ :data:`string.uppercase`) are gone. Use
+ :data:`string.ascii_letters` etc. instead. (The reason for the
+ removal is that :data:string.letters` and friends had
+ locale-specific behavior, which is a bad idea for such
+ attractively-named global "constants".)
+
+* Removed: :func:`apply`. Instead of ``apply(f, args)`` use
+ ``f(*args)``.
+
+* Removed :func:`callable`. Instead of ``callable(f)`` you can use
+ ``hasattr(f, '__call__')``. The :func:`operator.isCallable` function
+ is also gone.
+
+* Removed :func:`coerce`. This function no longer serves a purpose
+ now that classic classes are gone.
+
+* Removed :func:`execfile`. Instead of ``execfile(fn)`` use
+ ``exec(open(fn).read())``.
-* Removed: :func:`apply`, :func:`callable`, :func:`coerce`, :func:`execfile`,
- :func:`file`, :func:`reduce`, :func:`reload`.
+* Removed :class:`file`. Use :func:`open`.
-* Removed: :meth:`dict.has_key` -- use the ``in`` operator instead.
+* Removed :func:`reduce`. Use :func:`functools.reduce` if you really
+ need it; however, 99 percent of the time an explicit :keyword:`for`
+ loop is more readable.
-* :func:`exec` is now a function.
+* Removed :func:`reload`. Use :func:`imp.reload`.
-* The :meth:`__oct__` and :meth:`__hex__` special methods are removed --
- :func:`oct` and :func:`hex` use :meth:`__index__` now to convert the argument
- to an integer.
+* Removed. :meth:`dict.has_key` -- use the :keyword:`in` operator
+ instead.
-* Support is removed for :attr:`__members__` and :attr:`__methods__`.
+* The :meth:`__oct__` and :meth:`__hex__` special methods are removed
+ -- :func:`oct` and :func:`hex` use :meth:`__index__` now to convert
+ the argument to an integer.
-* Renamed the boolean conversion C-level slot and method: ``nb_nonzero`` is now
- ``nb_bool`` and :meth:`__nonzero__` is now :meth:`__bool__`.
+* Removed support for :attr:`__members__` and :attr:`__methods__`.
+* Renamed the boolean conversion C-level slot and method:
+ ``nb_nonzero`` is now ``nb_bool`` and :meth:`__nonzero__` is now
+ :meth:`__bool__`.
+
+* Renamed module :mod:`__builtin__` to :mod:`builtins` (removing the
+ underscores, adding an 's'). The :data:`__builtins__` variable
+ found in most global namespaces is unchanged. To modify a builtin,
+ you should use :mod:`builtins`, not :data:`__builtins__`!
+
+* Renamed function attributes :attr:`func_whatever` to
+ :attr:`__whatever__`. XXX list every single one.
+
+* Removed :exc:`StandardError`.
+
+* Removed METH_OLDARGS and WITH_CYCLE_GC. XXX more.
.. ======================================================================
@@ -616,11 +678,11 @@
Optimizations
-------------
-* Detailed changes are listed here.
-
The net result of the 3.0 generalizations is that Python 3.0 runs the
-pystone benchmark around a third slower than Python 2.5. There's room
-for improvement, but it will happen after 3.0 is released!
+pystone benchmark around 10% slower than Python 2.5. Most likely the
+biggest cause is the removal of special-casing for small integers.
+There's room for improvement, but it will happen after 3.0 is
+released!
.. ======================================================================
@@ -668,11 +730,11 @@
Changes to Python's build process and to the C API include:
-* PEP 3118: New Buffer API.
+* :pep:`3118`: New Buffer API. XXX
-* PEP 3121: Extension Module Initialization & Finalization.
+* :pep:`3121`: Extension Module Initialization & Finalization. XXX
-* PEP 3123: Making :cmacro:`PyObject_HEAD` conform to standard C.
+* :pep:`3123`: Making :cmacro:`PyObject_HEAD` conform to standard C. XXX
* No more C API support for restricted execution.
@@ -689,8 +751,9 @@
Port-Specific Changes
---------------------
-Platform-specific changes go here.
+XXX Platform-specific changes go here.
+* XXX BeOS, RISCOS, Irix, Tru64 support
.. ======================================================================
@@ -705,9 +768,9 @@
logs finds there were XXX patches applied and YYY bugs fixed between
Python 2.6 and 3.0. Both figures are likely to be underestimates.
-Some of the more notable changes are:
+XXX Some of the more notable changes are:
-* Details go here.
+* XXX Details go here.
.. ======================================================================