diff options
Diffstat (limited to 'Doc/whatsnew')
| -rw-r--r-- | Doc/whatsnew/3.0.rst | 585 |
1 files changed, 296 insertions, 289 deletions
diff --git a/Doc/whatsnew/3.0.rst b/Doc/whatsnew/3.0.rst index 9592d80..c195f53 100644 --- a/Doc/whatsnew/3.0.rst +++ b/Doc/whatsnew/3.0.rst @@ -4,8 +4,6 @@ .. XXX Add trademark info for Apple, Microsoft. -.. XXX Remove duplicates; just put info in the most relevant section. - :Author: Guido van Rossum :Release: |release| :Date: |today| @@ -132,112 +130,6 @@ Note: :func:`print` function calls, so this is mostly a non-issue for larger projects. -Text Vs. Data Instead Of Unicode Vs. 8-bit ------------------------------------------- - -Everything you thought you knew about binary data and Unicode has -changed: - -XXX HIRO - -* Python 3.0 uses the concepts of *text* and (binary) *data* instead - of Unicode strings and 8-bit strings. All text is Unicode; however - *encoded* Unicode is represented as binary data. The type used to - hold text is :class:`str`, the type used to hold data is - :class:`bytes`. The difference is that any attempt to mix text and - data in Python 3.0 raises a TypeError exception, whereas if you were - to mix Unicode and 8-bit strings in Python 2.x, you would only get - an exception if the 8-bit string contained non-ASCII values. As a - consequence, pretty much all code that uses Unicode, encodings or - binary data most likely has to change. The change is for the - better, as in the 2.x world there were numerous bugs having to do - with mixing encoded and unencoded text. - -* You no longer use ``u"..."`` literals for Unicode text. However, - you must use ``b"..."`` literals for binary data. - -* Files opened as text files (still the default mode for :func:`open`) - always use an encoding to map between strings (in memory) and bytes - (on disk). Binary files (opened with a ``b`` in the mode argument) - always use bytes in memory. This means that if a file is opened - using an incorrect mode or encoding, I/O will likely fail. It also - means that even Unix users will have to specify the correct mode - (text or binary) when opening a file. There is a platform-dependent - default encoding, which on Unixy platforms can be set with the - ``LANG`` environment variable (and sometimes also with some other - platform-specific locale-related environment variables). In many - cases, but not all, the system default is UTF-8; you should never - count on this default. Any application reading or writing more than - pure ASCII text should probably have a way to override the encoding. - -* 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. - -* Filenames are passed to and returned from APIs as (Unicode) strings. - This can present platform-specific problems because on some - platforms filenames are arbitrary byte strings. (On the other hand - on Windows, filenames are natively stored as Unicode.) As a - work-around, most APIs (e.g. :func:`open` and many functions in the - :mod:`os` module) that take filenames accept :class:`bytes` objects - as well as strings, and a few APIs have a way to ask for a - :class:`bytes` return value: :func:`os.listdir` returns a - :class:`bytes` instance if the argument is a :class:`bytes` - instance, and :func:`os.getcwdu` returns the current working - directory as a :class:`bytes` instance. - -* Some system APIs like :data:`os.environ` and :data:`sys.argv` can - also present problems when the bytes made available by the system is - not interpretable using the default encoding. Setting the ``LANG`` - variable and rerunning the program is probably the best approach. - -* All backslashes in raw strings are interpreted literally. This - means that ``'\U'`` and ``'\u'`` escapes in raw strings are not - treated specially. - -XXX Deal with dupes below - -* There is only one text string type; its name is :class:`str` but its - behavior and implementation are like :class:`unicode` in 2.x. - -* The :class:`basestring` superclass has been removed. The ``2to3`` - tool (see below) 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 - it is decoded). 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. - -* Like :class:`str`, the :class:`bytes` type is immutable. There is a - separate *mutable* type to hold buffered binary data, - :class:`bytearray`. Nearly all APIs that accept :class:`bytes` also - accept :class:`bytearray`. The mutable API is based on - :class:`collections.MutableSequence`. - -* :pep:`3138`: The :func:`repr` of a string no longer escapes - non-ASCII characters. It still escapes control characters and code - points with non-printable status in the Unicode standard, however. - -* :pep:`3120`: The default source encoding is now UTF-8. - -* :pep:`3131`: Non-ASCII letters are now allowed in 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 compatible, but completely reimplemented (currently largely - in Python). Also, binary files use bytes instead of strings. - -* The :mod:`StringIO` and :mod:`cStringIO` modules are gone. Instead, - import :class:`io.StringIO` or :class:`io.BytesIO`, for text and - data respectively. - -* See also the :ref:`unicode-howto`, which was updated for Python 3.0. - Views And Iterators Instead Of Lists ------------------------------------- @@ -277,12 +169,13 @@ Python 3.0 has simplified the rules for ordering comparisons: elements must be comparable to each other. Note that this does not apply to the ``==`` and ``!=`` operators: objects of different uncomparable types always compare unequal to each other, and an - object always compares equal to itself (i.e., ``x is y`` implies ``x - = y``; this is true even for ``NaN``). + object always compares equal to itself (i.e., ``x is y`` implies + ``x == y``; this is true even for *NaN*). -* :meth:`builtin.sorted` and :meth:`list.sort` no longer accept the *cmp* - argument providing a comparison function. Use the *key* argument - instead. N.B. the *key* and *reverse* arguments are now "keyword-only". +* :meth:`builtin.sorted` and :meth:`list.sort` no longer accept the + *cmp* argument providing a comparison function. Use the *key* + argument instead. N.B. the *key* and *reverse* arguments are now + "keyword-only". * The :func:`cmp` function is gone, and the :meth:`__cmp__` special method is no longer supported. Use :meth:`__lt__` for sorting, @@ -316,6 +209,115 @@ Integers * Octal literals are no longer of the form ``0720``; use ``0o720`` instead. +Text Vs. Data Instead Of Unicode Vs. 8-bit +------------------------------------------ + +Everything you thought you knew about binary data and Unicode has +changed. + +* Python 3.0 uses the concepts of *text* and (binary) *data* instead + of Unicode strings and 8-bit strings. All text is Unicode; however + *encoded* Unicode is represented as binary data. The type used to + hold text is :class:`str`, the type used to hold data is + :class:`bytes`. The biggest difference with the 2.x situation is + that any attempt to mix text and data in Python 3.0 raises + :ext:`TypeError`, whereas if you were to mix Unicode and 8-bit + strings in Python 2.x, it would work if the 8-bit string happened to + contain only 7-bit (ASCII) bytes, but you would get + :ext:`UnicodeDecodeError` if it contained non-ASCII values. This + value-specific behavior has caused numerous sad faces over the + years. + +* As a consequence of this change in philosophy, pretty much all code + that uses Unicode, encodings or binary data most likely has to + change. The change is for the better, as in the 2.x world there + were numerous bugs having to do with mixing encoded and unencoded + text. To be prepared in Python 2.x, start using :class:`unicode` + for all unencoded text, and :class:`str` for binary or encoded data + only. Then the ``2to3`` tool will do most of the work for you. + +* You can no longer use ``u"..."`` literals for Unicode text. + However, you must use ``b"..."`` literals for binary data. + +* As the :class:`str` and :class:`bytes` types cannot be mixed, you + must always explicitly convert between them. Use :meth:`str.encode` + to go from :class:`str` to :class:`bytes`, and :meth:`bytes.decode` + to go from :class:`bytes` to :class:`str`. You can also use + ``bytes(s, encoding=...)`` and ``str(b, encoding=...)``, + respectively. + +* Like :class:`str`, the :class:`bytes` type is immutable. There is a + separate *mutable* type to hold buffered binary data, + :class:`bytearray`. Nearly all APIs that accept :class:`bytes` also + accept :class:`bytearray`. The mutable API is based on + :class:`collections.MutableSequence`. + +* All backslashes in raw string literals are interpreted literally. + This means that ``'\U'`` and ``'\u'`` escapes in raw strings are not + treated specially. For example, ``r'\u20ac'`` is a string of 6 + characters in Python 3.0, whereas in 2.6, ``ur'\u20ac'`` was the + single "euro" character. (Of course, this change only affects raw + string literals; the euro character is ``'\u20ac'`` in Python 3.0.) + +* 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. The ``2to3`` tool (see below) replaces every occurrence of + :class:`basestring` with :class:`str`. + +* Files opened as text files (still the default mode for :func:`open`) + always use an encoding to map between strings (in memory) and bytes + (on disk). Binary files (opened with a ``b`` in the mode argument) + always use bytes in memory. This means that if a file is opened + using an incorrect mode or encoding, I/O will likely fail loudly, + instead of silently producing incorrect data. It also means that + even Unix users will have to specify the correct mode (text or + binary) when opening a file. There is a platform-dependent default + encoding, which on Unixy platforms can be set with the ``LANG`` + environment variable (and sometimes also with some other + platform-specific locale-related environment variables). In many + cases, but not all, the system default is UTF-8; you should never + count on this default. Any application reading or writing more than + pure ASCII text should probably have a way to override the encoding. + There is no longer any need for using the encoding-aware streams + in the :mod:`codecs` module. + +* Filenames are passed to and returned from APIs as (Unicode) strings. + This can present platform-specific problems because on some + platforms filenames are arbitrary byte strings. (On the other hand, + on Windows filenames are natively stored as Unicode.) As a + work-around, most APIs (e.g. :func:`open` and many functions in the + :mod:`os` module) that take filenames accept :class:`bytes` objects + as well as strings, and a few APIs have a way to ask for a + :class:`bytes` return value. Thus, :func:`os.listdir` returns a + list of :class:`bytes` instances if the argument is a :class:`bytes` + instance, and :func:`os.getcwdu` returns the current working + directory as a :class:`bytes` instance. Note that when + :func:`os.listdir` returns a list of strings, filenames that + cannot be decoded properly are omitted rather than raising + :exc:`UnicodeError`. + +* Some system APIs like :data:`os.environ` and :data:`sys.argv` can + also present problems when the bytes made available by the system is + not interpretable using the default encoding. Setting the ``LANG`` + variable and rerunning the program is probably the best approach. + +* :pep:`3138`: The :func:`repr` of a string no longer escapes + non-ASCII characters. It still escapes control characters and code + points with non-printable status in the Unicode standard, however. + +* :pep:`3120`: The default source encoding is now UTF-8. + +* :pep:`3131`: Non-ASCII letters are now allowed in identifiers. + (However, the standard library remains ASCII-only with the exception + of contributor names in comments.) + +* The :mod:`StringIO` and :mod:`cStringIO` modules are gone. Instead, + import the :mod:`io` module and use :class:`io.StringIO` or + :class:`io.BytesIO` for text and data respectively. + +* See also the :ref:`unicode-howto`, which was updated for Python 3.0. + Overview Of Syntax Changes ========================== @@ -341,8 +343,8 @@ New Syntax * 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 (see :pep:`3115`), but can be used for other purposes as - well, as long as the metaclass supports it. + a metaclass (see next section), but can be used for other purposes + as well, as long as the metaclass supports it. * :pep:`3104`: :keyword:`nonlocal` statement. Using ``nonlocal x`` you can now assign directly to a variable in an outer (but @@ -376,8 +378,8 @@ New Syntax Changed Syntax -------------- -* New :keyword:`raise` statement syntax: ``raise [expr [from expr]]``. - Also note that string exceptions are no longer legal (:pep:`0352`). +* :pep:`3109` and :pep:`3134`: new :keyword:`raise` statement syntax: + ``raise [expr [from expr]]``. See below. * :keyword:`as` and :keyword:`with` are now reserved words. (Since 2.6, actually.) @@ -389,6 +391,22 @@ Changed Syntax * Change from :keyword:`except` *exc*, *var* to :keyword:`except` *exc* :keyword:`as` *var*. See :pep:`3110`. +* :pep:`3115`: New Metaclass Syntax. Instead of:: + + class C: + __metaclass__ = M + ... + + you must now use:: + + class C(metaclass=M): + ... + + The module-global :data:`__metaclass__` variable is no longer + supported. (It was a crutch to make it easier to default to + new-style classes without deriving every class from + :class:`object`.) + * List comprehensions no longer support the syntactic form ``[... for var in item1, item2, ...]``. Use ``[... for var in (item1, item2, ...)]`` instead. @@ -430,6 +448,8 @@ Removed Syntax not starting with ``.`` are always interpreted as absolute imports. (:pep:`0328`) +* Classic classes are gone. + Changes Already Present In Python 2.6 ===================================== @@ -551,9 +571,10 @@ review: considered implementation details of the pure Python versions. Users should always import the standard version, which attempts to import the accelerated version and falls back to the pure Python - version. The :mod:`pickle` module received this treatment. The - :mod:`profile` module is on the list for 3.1. The :mod:`StringIO` - module has been turned into a class in the :mod:`io` module. + version. The :mod:`pickle` / :mod:`cPickle` pair received this + treatment. The :mod:`profile` module is on the list for 3.1. The + :mod:`StringIO` module has been turned into a class in the :mod:`io` + module. * Some related modules have been grouped into packages, and usually the submodule names have been simplified. The resulting new @@ -579,7 +600,8 @@ review: * :mod:`xmlrpc` (:mod:`xmlrpclib`, :mod:`DocXMLRPCServer`, :mod:`SimpleXMLRPCServer`). -Some other library changes (not covered by :pep:`3108`): +Some other changes to standard library moduled, not covered by +:pep:`3108`: * Killed :mod:`sets`. Use the builtin :func:`set` function. @@ -601,6 +623,28 @@ Some other library changes (not covered by :pep:`3108`): * Cleanup of the :mod:`random` module: removed the :func:`jumpahead` API. +* The :mod:`new` module is gone. + +* The functions :func:`os.tmpnam`, :func:`os.tempnam` and + :func:`os.tmpfile` have been removed in favor of the :mod:`tempfile` + module. + +* The :mod:`tokenize` module has been changed to work with bytes. The + main entry point is now :func:`tokenize.tokenize`, instead of + generate_tokens. + +* :data:`string.letters` and its friends (:data:`string.lowercase` and + :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".) + +* 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__`! + :pep:`3101`: A New Approach To String Formatting ================================================ @@ -612,81 +656,86 @@ Some other library changes (not covered by :pep:`3108`): scoop. -: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 :-) - -* The :meth:`dict.iterkeys`, :meth:`dict.itervalues` and :meth:`dict.iteritems` - methods have been removed. - -* :meth:`dict.keys`, :meth:`dict.values` and :meth:`dict.items` return objects - with set behavior that reference the underlying dict; these are often - referred to as *dictionary views*. +Changes To Exceptions +===================== - -Exception Stuff -=============== +The APIs for raising and catching exception have been cleaned up and +new powerful features added: * :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 + hierarchy. This is not new as a recommendation, but the *requirement* to inherit from :exc:`BaseException` is new. (Python 2.6 still allowed classic classes to be raised, and placed no - restriction on what you can catch.) - -* :exc:`StandardError` was removed (in 2.6, actually). - -* Dropping sequence behavior (slicing!) and :attr:`message` attribute of - exception instances. - -* :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 - identifier:`` instead of ``except Exception, identifier:`` - -* :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 - application``. Strings now deal with non-English locales. - - -New Class And Metaclass Stuff -============================= - -XXX Move to new syntax section??? - -* Classic classes are gone. - -* :pep:`3115`: New Metaclass Syntax. Instead of:: - - class C: - __metaclass__ = M - ... - - you now use:: - - class C(metaclass=M): - ... - - The module-global :data:`__metaclass__` variable is no longer supported. - (It was a crutch to make it easier to default to new-style classes - without deriving every class from :class:`object`.) - - -Other Language Changes -====================== - -* Moved :func:`intern` to :func:`sys.intern`. + restriction on what you can catch.) As a consequence, string + exceptions are finally truly and utterly dead. + +* Almost all exceptions should actually derive from :exc:`Exception`; + :exc:`BaseException` should only be used as a base class for + exceptions that should only be handled at the top level, such as + :exc:`SystemExit` or :exc:`KeyboardInterrupt`. The recommended + idiom for handling all exceptions except for this latter category is + to use :keyword:`except` :exc:`Exception`. + +* :exc:`StandardError` was removed (in 2.6 already). + +* Exceptions no longer behave as sequences. Use the :attr:`args` + attribute instead. + +* :pep:`3109`: Raising exceptions. You must now use :keyword:`raise` + *Exception*(*args*) instead of :keyword:`raise` *Exception*, *args*. + Additionally, you can no longer explicitly specify a traceback; + instead, if you *have* to do this, you can assign directly to the + :attr:`__traceback__` attribute (see below). + +* :pep:`3110`: Catching exceptions. You must now use + *:keyword:`except` SomeException* :keyword:`as` *variable* instead + *of :keyword:`except` *SomeException*, variable*. Moreover, the + *variable* is explicitly deleted when the :keyword:`except` block + is left. + +* :pep:`3134`: Exception chaining. There are two cases: implicit + chaining and explicit chaining. Implicit chaining happens when an + exception is raised in an :keyword:`except` or :keyword:`finally` + handler block. This usually happens due to a bug in the handler + block; we call this a *secondary* exception. In this case, the + original exception (that was being handled) is saved as the + :attr:`__context__` attribute of the secondary exception. + Explicit chaining is invoked with this syntax:: + + raise SecondaryException() from primary_exception + + (where *primary_exception* is any expression that produces an + exception object, probably an exception that was previously caught). + In this case, the primary exception is stored on the + :attr:`__cause__` attribute of the secondary exception. The + traceback printed when an unhandled exception occurs walks the chain + of :attr:`__cause__` and :attr:`__context__` attributes and prints a + separate traceback for each component of the chain, with the primary + exception at the top. (Java users may recognize this behavior. :-) + +* :pep:`3134`: Exception objects now store their traceback as the + :attr:`__traceback__` attribute. This means that an exception + object now contains all the information pertaining to an exception, + and there are fewer reasons to use :func:`sys.exc_info` (though the + latter is not removed). + +* 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 application``. Strings now deal with non-English + locales. + + +Miscellaneous Other Changes +=========================== + +Operators And Special Methods +----------------------------- * ``!=`` now returns the opposite of ``==``, unless ``==`` returns - ``NotImplemented``. + :data:`NotImplemented`. -* The concept of "unbound methods" was removed from the language. +* The concept of "unbound methods" has been removed from the language. When referencing a method as a class attribute, you now get a plain function object. @@ -696,27 +745,46 @@ Other Language Changes :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())``. +* :pep:`3114`: the standard :meth:`next` method has been renamed to + :meth:`__next__`. + +* 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 support for :attr:`__members__` and :attr:`__methods__`. + +* The function attributes named :attr:`func_X` have been renamed to + use the :data:`__X__` form, freeing up these names in the function + attribute namespace for user-defined attributes. To wit, + :attr:`func_closure`, :attr:`func_code`, :attr:`func_defaults`, + :attr:`func_dict`, :attr:`func_doc`, :attr:`func_globals`, + :attr:`func_name` were renamed to :attr:`__closure__`, + :attr:`__code__`, :attr:`__defaults__`, :attr:`__dict__`, + :attr:`__doc__`, :attr:`__globals__`, :attr:`__name__`, + respectively. -* :pep:`3114`: ``.next()`` renamed to :meth:`__next__`, new builtin - :func:`next` to call the :meth:`__next__` method on an object. +* :meth:`__nonzero__` is now :meth:`__bool__`. + +Builtins +-------- * :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. + without arguments and (assuming this is in a regular instance method + defined inside a :keyword:`class` statement) the right class and + instance will automatically be chosen. With arguments, the behavior + of :func:`super` is unchanged. -* :func:`zip`, :func:`map` and :func:`filter` return iterators. +* :pep:`3111`: :func:`raw_input` was 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())``. -* :data:`string.letters` and its friends (:data:`string.lowercase` and - :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".) +* A new builtin :func:`next` was added to call the :meth:`__next__` + method on an object. + +* Moved :func:`intern` to :func:`sys.intern`. * Removed: :func:`apply`. Instead of ``apply(f, args)`` use ``f(*args)``. @@ -742,110 +810,49 @@ Other Language Changes * Removed. :meth:`dict.has_key` -- use the :keyword:`in` operator instead. -* 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 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. - -.. ====================================================================== - - -Optimizations -------------- - -The net result of the 3.0 generalizations is that Python 3.0 runs the -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! - .. ====================================================================== -New, Improved, And Deprecated Modules -===================================== - -As usual, Python's standard library received a number of enhancements and bug -fixes. Here's a partial list of the most notable changes, sorted alphabetically -by module name. Consult the :file:`Misc/NEWS` file in the source tree for a more -complete list of changes, or look through the Subversion logs for all the -details. - -* The :mod:`cPickle` module is gone. Use :mod:`pickle` instead. Eventually - we'll have a transparent accelerator module. - -* The :mod:`imageop` module is gone. - -* The :mod:`audiodev`, :mod:`Bastion`, :mod:`bsddb185`, :mod:`exceptions`, - :mod:`linuxaudiodev`, :mod:`md5`, :mod:`MimeWriter`, :mod:`mimify`, - :mod:`popen2`, :mod:`rexec`, :mod:`sets`, :mod:`sha`, :mod:`stringold`, - :mod:`strop`, :mod:`sunaudiodev`, :mod:`timing`, and :mod:`xmllib` modules are - gone. - -* The :mod:`bsddb` module is gone. It is being maintained externally - with its own release schedule better mirroring that of BerkeleyDB. - See http://www.jcea.es/programacion/pybsddb.htm. - -* The :mod:`new` module is gone. - -* The functions :func:`os.tmpnam`, :func:`os.tempnam` and :func:`os.tmpfile` - have been removed in favor of the :mod:`tempfile` module. - -* The :mod:`tokenize` module has been changed to work with bytes. The main - entry point is now :func:`tokenize.tokenize`, instead of generate_tokens. - -.. ====================================================================== -.. whole new modules get described in subsections here - -.. ====================================================================== - - -Build And C API Changes +Build and C API Changes ======================= -Changes to Python's build process and to the C API include: +Due to time constraints, here is a *very* incomplete list of changes +to the C API. + +* Support for several platforms was dropped, including but not limited + to Mac OS 9, BeOS, RISCOS, Irix, and Tru64. -* :pep:`3118`: New Buffer API. XXX +* :pep:`3118`: New Buffer API. -* :pep:`3121`: Extension Module Initialization & Finalization. XXX +* :pep:`3121`: Extension Module Initialization & Finalization. -* :pep:`3123`: Making :cmacro:`PyObject_HEAD` conform to standard C. XXX +* :pep:`3123`: Making :cmacro:`PyObject_HEAD` conform to standard C. * No more C API support for restricted execution. -* :cfunc:`PyNumber_Coerce`, :cfunc:`PyNumber_CoerceEx`, :cfunc:`PyMember_Get`, - and :cfunc:`PyMember_Set` C APIs are removed. +* :cfunc:`PyNumber_Coerce`, :cfunc:`PyNumber_CoerceEx`, + :cfunc:`PyMember_Get`, and :cfunc:`PyMember_Set` C APIs are removed. * New C API :cfunc:`PyImport_ImportModuleNoBlock`, works like - :cfunc:`PyImport_ImportModule` but won't block on the import lock (returning - an error instead). + :cfunc:`PyImport_ImportModule` but won't block on the import lock + (returning an error instead). -.. ====================================================================== +* Renamed the boolean conversion C-level slot and method: + ``nb_nonzero`` is now ``nb_bool``. +* Removed ``METH_OLDARGS`` and ``WITH_CYCLE_GC`` from the C API. + +.. ====================================================================== -Port-Specific Changes ---------------------- -XXX Platform-specific changes go here. +Performance +=========== -* XXX BeOS, RISCOS, Irix, Tru64 support +The net result of the 3.0 generalizations is that Python 3.0 runs the +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! .. ====================================================================== |