| **************************** |
| What's New In Python 3.3 |
| **************************** |
| |
| :Author: Raymond Hettinger |
| :Release: |release| |
| :Date: |today| |
| |
| .. Rules for maintenance: |
| |
| * Anyone can add text to this document. Do not spend very much time |
| on the wording of your changes, because your text will probably |
| get rewritten to some degree. |
| |
| * The maintainer will go through Misc/NEWS periodically and add |
| changes; it's therefore more important to add your changes to |
| Misc/NEWS than to this file. |
| |
| * This is not a complete list of every single change; completeness |
| is the purpose of Misc/NEWS. Some changes I consider too small |
| or esoteric to include. If such a change is added to the text, |
| I'll just remove it. (This is another reason you shouldn't spend |
| too much time on writing your addition.) |
| |
| * If you want to draw your new text to the attention of the |
| maintainer, add 'XXX' to the beginning of the paragraph or |
| section. |
| |
| * It's OK to just add a fragmentary note about a change. For |
| example: "XXX Describe the transmogrify() function added to the |
| socket module." The maintainer will research the change and |
| write the necessary text. |
| |
| * You can comment out your additions if you like, but it's not |
| necessary (especially when a final release is some months away). |
| |
| * Credit the author of a patch or bugfix. Just the name is |
| sufficient; the e-mail address isn't necessary. |
| |
| * It's helpful to add the bug/patch number as a comment: |
| |
| XXX Describe the transmogrify() function added to the socket |
| module. |
| (Contributed by P.Y. Developer in :issue:`12345`.) |
| |
| This saves the maintainer the effort of going through the Mercurial log |
| when researching a change. |
| |
| This article explains the new features in Python 3.3, compared to 3.2. |
| |
| |
| .. pep-3118-update: |
| |
| PEP 3118: New memoryview implementation and buffer protocol documentation |
| ========================================================================= |
| |
| :issue:`10181` - memoryview bug fixes and features. |
| Written by Stefan Krah. |
| |
| The new memoryview implementation comprehensively fixes all ownership and |
| lifetime issues of dynamically allocated fields in the Py_buffer struct |
| that led to multiple crash reports. Additionally, several functions that |
| crashed or returned incorrect results for non-contiguous or multi-dimensional |
| input have been fixed. |
| |
| The memoryview object now has a PEP-3118 compliant getbufferproc() |
| that checks the consumer's request type. Many new features have been |
| added, most of them work in full generality for non-contiguous arrays |
| and arrays with suboffsets. |
| |
| The documentation has been updated, clearly spelling out responsibilities |
| for both exporters and consumers. Buffer request flags are grouped into |
| basic and compound flags. The memory layout of non-contiguous and |
| multi-dimensional NumPy-style arrays is explained. |
| |
| Features |
| -------- |
| |
| * All native single character format specifiers in struct module syntax |
| (optionally prefixed with '@') are now supported. |
| |
| * With some restrictions, the cast() method allows changing of format and |
| shape of C-contiguous arrays. |
| |
| * Multi-dimensional list representations are supported for any array type. |
| |
| * Multi-dimensional comparisons are supported for any array type. |
| |
| * All array types are hashable if the exporting object is hashable |
| and the view is read-only. (Contributed by Antoine Pitrou in |
| :issue:`13411`) |
| |
| |
| * Arbitrary slicing of any 1-D arrays type is supported. For example, it |
| is now possible to reverse a memoryview in O(1) by using a negative step. |
| |
| API changes |
| ----------- |
| |
| * The maximum number of dimensions is officially limited to 64. |
| |
| * The representation of empty shape, strides and suboffsets is now |
| an empty tuple instead of None. |
| |
| * Accessing a memoryview element with format 'B' (unsigned bytes) |
| now returns an integer (in accordance with the struct module syntax). |
| For returning a bytes object the view must be cast to 'c' first. |
| |
| * For further changes see `Build and C API Changes`_ and `Porting C code`_ . |
| |
| .. _pep-393: |
| |
| PEP 393: Flexible String Representation |
| ======================================= |
| |
| The Unicode string type is changed to support multiple internal |
| representations, depending on the character with the largest Unicode ordinal |
| (1, 2, or 4 bytes) in the represented string. This allows a space-efficient |
| representation in common cases, but gives access to full UCS-4 on all |
| systems. For compatibility with existing APIs, several representations may |
| exist in parallel; over time, this compatibility should be phased out. |
| |
| On the Python side, there should be no downside to this change. |
| |
| On the C API side, PEP 393 is fully backward compatible. The legacy API |
| should remain available at least five years. Applications using the legacy |
| API will not fully benefit of the memory reduction, or - worse - may use |
| a bit more memory, because Python may have to maintain two versions of each |
| string (in the legacy format and in the new efficient storage). |
| |
| Functionality |
| ------------- |
| |
| Changes introduced by :pep:`393` are the following: |
| |
| * Python now always supports the full range of Unicode codepoints, including |
| non-BMP ones (i.e. from ``U+0000`` to ``U+10FFFF``). The distinction between |
| narrow and wide builds no longer exists and Python now behaves like a wide |
| build, even under Windows. |
| |
| * With the death of narrow builds, the problems specific to narrow builds have |
| also been fixed, for example: |
| |
| * :func:`len` now always returns 1 for non-BMP characters, |
| so ``len('\U0010FFFF') == 1``; |
| |
| * surrogate pairs are not recombined in string literals, |
| so ``'\uDBFF\uDFFF' != '\U0010FFFF'``; |
| |
| * indexing or slicing non-BMP characters returns the expected value, |
| so ``'\U0010FFFF'[0]`` now returns ``'\U0010FFFF'`` and not ``'\uDBFF'``; |
| |
| * all other functions in the standard library now correctly handle |
| non-BMP codepoints. |
| |
| * The value of :data:`sys.maxunicode` is now always ``1114111`` (``0x10FFFF`` |
| in hexadecimal). The :c:func:`PyUnicode_GetMax` function still returns |
| either ``0xFFFF`` or ``0x10FFFF`` for backward compatibility, and it should |
| not be used with the new Unicode API (see :issue:`13054`). |
| |
| * The :file:`./configure` flag ``--with-wide-unicode`` has been removed. |
| |
| Performance and resource usage |
| ------------------------------ |
| |
| The storage of Unicode strings now depends on the highest codepoint in the string: |
| |
| * pure ASCII and Latin1 strings (``U+0000-U+00FF``) use 1 byte per codepoint; |
| |
| * BMP strings (``U+0000-U+FFFF``) use 2 bytes per codepoint; |
| |
| * non-BMP strings (``U+10000-U+10FFFF``) use 4 bytes per codepoint. |
| |
| The net effect is that for most applications, memory usage of string |
| storage should decrease significantly - especially compared to former |
| wide unicode builds - as, in many cases, strings will be pure ASCII |
| even in international contexts (because many strings store non-human |
| language data, such as XML fragments, HTTP headers, JSON-encoded data, |
| etc.). We also hope that it will, for the same reasons, increase CPU |
| cache efficiency on non-trivial applications. The memory usage of |
| Python 3.3 is two to three times smaller than Python 3.2, and a little |
| bit better than Python 2.7, on a Django benchmark (see the PEP for |
| details). |
| |
| |
| PEP 3151: Reworking the OS and IO exception hierarchy |
| ===================================================== |
| |
| :pep:`3151` - Reworking the OS and IO exception hierarchy |
| PEP written and implemented by Antoine Pitrou. |
| |
| The hierarchy of exceptions raised by operating system errors is now both |
| simplified and finer-grained. |
| |
| You don't have to worry anymore about choosing the appropriate exception |
| type between :exc:`OSError`, :exc:`IOError`, :exc:`EnvironmentError`, |
| :exc:`WindowsError`, :exc:`mmap.error`, :exc:`socket.error` or |
| :exc:`select.error`. All these exception types are now only one: |
| :exc:`OSError`. The other names are kept as aliases for compatibility |
| reasons. |
| |
| Also, it is now easier to catch a specific error condition. Instead of |
| inspecting the ``errno`` attribute (or ``args[0]``) for a particular |
| constant from the :mod:`errno` module, you can catch the adequate |
| :exc:`OSError` subclass. The available subclasses are the following: |
| |
| * :exc:`BlockingIOError` |
| * :exc:`ChildProcessError` |
| * :exc:`ConnectionError` |
| * :exc:`FileExistsError` |
| * :exc:`FileNotFoundError` |
| * :exc:`InterruptedError` |
| * :exc:`IsADirectoryError` |
| * :exc:`NotADirectoryError` |
| * :exc:`PermissionError` |
| * :exc:`ProcessLookupError` |
| * :exc:`TimeoutError` |
| |
| And the :exc:`ConnectionError` itself has finer-grained subclasses: |
| |
| * :exc:`BrokenPipeError` |
| * :exc:`ConnectionAbortedError` |
| * :exc:`ConnectionRefusedError` |
| * :exc:`ConnectionResetError` |
| |
| Thanks to the new exceptions, common usages of the :mod:`errno` can now be |
| avoided. For example, the following code written for Python 3.2:: |
| |
| from errno import ENOENT, EACCES, EPERM |
| |
| try: |
| with open("document.txt") as f: |
| content = f.read() |
| except IOError as err: |
| if err.errno == ENOENT: |
| print("document.txt file is missing") |
| elif err.errno in (EACCES, EPERM): |
| print("You are not allowed to read document.txt") |
| else: |
| raise |
| |
| can now be written without the :mod:`errno` import and without manual |
| inspection of exception attributes:: |
| |
| try: |
| with open("document.txt") as f: |
| content = f.read() |
| except FileNotFoundError: |
| print("document.txt file is missing") |
| except PermissionError: |
| print("You are not allowed to read document.txt") |
| |
| |
| PEP 380: Syntax for Delegating to a Subgenerator |
| ================================================ |
| |
| :pep:`380` - Syntax for Delegating to a Subgenerator |
| PEP written by Greg Ewing. |
| |
| PEP 380 adds the ``yield from`` expression, allowing a generator to delegate |
| part of its operations to another generator. This allows a section of code |
| containing 'yield' to be factored out and placed in another generator. |
| Additionally, the subgenerator is allowed to return with a value, and the |
| value is made available to the delegating generator. |
| |
| While designed primarily for use in delegating to a subgenerator, the ``yield |
| from`` expression actually allows delegation to arbitrary subiterators. |
| |
| For simple iterators, ``yield from iterable`` is essentially just a shortened |
| form of ``for item in iterable: yield item``:: |
| |
| >>> def g(x): |
| ... yield from range(x, 0, -1) |
| ... yield from range(x) |
| ... |
| >>> list(g(5)) |
| [5, 4, 3, 2, 1, 0, 1, 2, 3, 4] |
| |
| However, unlike an ordinary loop, ``yield from`` allows subgenerators to |
| receive sent and thrown values directly from the calling scope, and |
| return a final value to the outer generator:: |
| |
| >>> def accumulate(start=0): |
| ... tally = start |
| ... while 1: |
| ... next = yield |
| ... if next is None: |
| ... return tally |
| ... tally += next |
| ... |
| >>> def gather_tallies(tallies, start=0): |
| ... while 1: |
| ... tally = yield from accumulate() |
| ... tallies.append(tally) |
| ... |
| >>> tallies = [] |
| >>> acc = gather_tallies(tallies) |
| >>> next(acc) # Ensure the accumulator is ready to accept values |
| >>> for i in range(10): |
| ... acc.send(i) |
| ... |
| >>> acc.send(None) # Finish the first tally |
| >>> for i in range(5): |
| ... acc.send(i) |
| ... |
| >>> acc.send(None) # Finish the second tally |
| >>> tallies |
| [45, 10] |
| |
| The main principle driving this change is to allow even generators that are |
| designed to be used with the ``send`` and ``throw`` methods to be split into |
| multiple subgenerators as easily as a single large function can be split into |
| multiple subfunctions. |
| |
| (Implementation by Greg Ewing, integrated into 3.3 by Renaud Blanch, Ryan |
| Kelly and Nick Coghlan, documentation by Zbigniew Jędrzejewski-Szmek and |
| Nick Coghlan) |
| |
| |
| PEP 409: Suppressing exception context |
| ====================================== |
| |
| :pep:`409` - Suppressing exception context |
| PEP written by Ethan Furman, implemented by Ethan Furman and Nick Coghlan. |
| |
| PEP 409 introduces new syntax that allows the display of the chained |
| exception context to be disabled. This allows cleaner error messages in |
| applications that convert between exception types:: |
| |
| >>> class D: |
| ... def __init__(self, extra): |
| ... self._extra_attributes = extra |
| ... def __getattr__(self, attr): |
| ... try: |
| ... return self._extra_attributes[attr] |
| ... except KeyError: |
| ... raise AttributeError(attr) from None |
| ... |
| >>> D({}).x |
| Traceback (most recent call last): |
| File "<stdin>", line 1, in <module> |
| File "<stdin>", line 8, in __getattr__ |
| AttributeError: x |
| |
| Without the ``from None`` suffix to suppress the cause, the original |
| exception would be displayed by default:: |
| |
| >>> class C: |
| ... def __init__(self, extra): |
| ... self._extra_attributes = extra |
| ... def __getattr__(self, attr): |
| ... try: |
| ... return self._extra_attributes[attr] |
| ... except KeyError: |
| ... raise AttributeError(attr) |
| ... |
| >>> C({}).x |
| Traceback (most recent call last): |
| File "<stdin>", line 6, in __getattr__ |
| KeyError: 'x' |
| |
| During handling of the above exception, another exception occurred: |
| |
| Traceback (most recent call last): |
| File "<stdin>", line 1, in <module> |
| File "<stdin>", line 8, in __getattr__ |
| AttributeError: x |
| |
| No debugging capability is lost, as the original exception context remains |
| available if needed (for example, if an intervening library has incorrectly |
| suppressed valuable underlying details):: |
| |
| >>> try: |
| ... D({}).x |
| ... except AttributeError as exc: |
| ... print(repr(exc.__context__)) |
| ... |
| KeyError('x',) |
| |
| |
| PEP 414: Explicit Unicode literals |
| ====================================== |
| |
| :pep:`414` - Explicit Unicode literals |
| PEP written by Armin Ronacher. |
| |
| To ease the transition from Python 2 for Unicode aware Python applications |
| that make heavy use of Unicode literals, Python 3.3 once again supports the |
| "``u``" prefix for string literals. This prefix has no semantic significance |
| in Python 3, it is provided solely to reduce the number of purely mechanical |
| changes in migrating to Python 3, making it easier for developers to focus on |
| the more significant semantic changes (such as the stricter default |
| separation of binary and text data). |
| |
| |
| PEP 3155: Qualified name for classes and functions |
| ================================================== |
| |
| :pep:`3155` - Qualified name for classes and functions |
| PEP written and implemented by Antoine Pitrou. |
| |
| Functions and class objects have a new ``__qualname__`` attribute representing |
| the "path" from the module top-level to their definition. For global functions |
| and classes, this is the same as ``__name__``. For other functions and classes, |
| it provides better information about where they were actually defined, and |
| how they might be accessible from the global scope. |
| |
| Example with (non-bound) methods:: |
| |
| >>> class C: |
| ... def meth(self): |
| ... pass |
| >>> C.meth.__name__ |
| 'meth' |
| >>> C.meth.__qualname__ |
| 'C.meth' |
| |
| Example with nested classes:: |
| |
| >>> class C: |
| ... class D: |
| ... def meth(self): |
| ... pass |
| ... |
| >>> C.D.__name__ |
| 'D' |
| >>> C.D.__qualname__ |
| 'C.D' |
| >>> C.D.meth.__name__ |
| 'meth' |
| >>> C.D.meth.__qualname__ |
| 'C.D.meth' |
| |
| Example with nested functions:: |
| |
| >>> def outer(): |
| ... def inner(): |
| ... pass |
| ... return inner |
| ... |
| >>> outer().__name__ |
| 'inner' |
| >>> outer().__qualname__ |
| 'outer.<locals>.inner' |
| |
| The string representation of those objects is also changed to include the |
| new, more precise information:: |
| |
| >>> str(C.D) |
| "<class '__main__.C.D'>" |
| >>> str(C.D.meth) |
| '<function C.D.meth at 0x7f46b9fe31e0>' |
| |
| |
| Other Language Changes |
| ====================== |
| |
| Some smaller changes made to the core Python language are: |
| |
| * Added support for Unicode name aliases and named sequences. |
| Both :func:`unicodedata.lookup()` and ``'\N{...}'`` now resolve name aliases, |
| and :func:`unicodedata.lookup()` resolves named sequences too. |
| |
| (Contributed by Ezio Melotti in :issue:`12753`) |
| |
| * Equality comparisons on :func:`range` objects now return a result reflecting |
| the equality of the underlying sequences generated by those range objects. |
| |
| (:issue:`13201`) |
| |
| * The ``count()``, ``find()``, ``rfind()``, ``index()`` and ``rindex()`` |
| methods of :class:`bytes` and :class:`bytearray` objects now accept an |
| integer between 0 and 255 as their first argument. |
| |
| (:issue:`12170`) |
| |
| * A dict lookup now raises a :exc:`RuntimeError` if the dict is modified during |
| the lookup. If you implement your own comparison function for objects used |
| as dict keys and the dict is shared by multiple threads, access to the dict |
| should be protected by a lock. |
| |
| (:issue:`14205`) |
| |
| * New methods have been added to :class:`list` and :class:`bytearray`: |
| ``copy()`` and ``clear()``. |
| |
| (:issue:`10516`) |
| |
| New and Improved Modules |
| ======================== |
| |
| abc |
| --- |
| |
| Improved support for abstract base classes containing descriptors composed with |
| abstract methods. The recommended approach to declaring abstract descriptors is |
| now to provide :attr:`__isabstractmethod__` as a dynamically updated |
| property. The built-in descriptors have been updated accordingly. |
| |
| * :class:`abc.abstractproperty` has been deprecated, use :class:`property` |
| with :func:`abc.abstractmethod` instead. |
| * :class:`abc.abstractclassmethod` has been deprecated, use |
| :class:`classmethod` with :func:`abc.abstractmethod` instead. |
| * :class:`abc.abstractstaticmethod` has been deprecated, use |
| :class:`staticmethod` with :func:`abc.abstractmethod` instead. |
| |
| (Contributed by Darren Dale in :issue:`11610`) |
| |
| array |
| ----- |
| |
| The :mod:`array` module supports the :c:type:`long long` type using ``q`` and |
| ``Q`` type codes. |
| |
| (Contributed by Oren Tirosh and Hirokazu Yamamoto in :issue:`1172711`) |
| |
| |
| bz2 |
| --- |
| |
| The :mod:`bz2` module has been rewritten from scratch. In the process, several |
| new features have been added: |
| |
| * :class:`bz2.BZ2File` can now read from and write to arbitrary file-like |
| objects, by means of its constructor's *fileobj* argument. |
| |
| (Contributed by Nadeem Vawda in :issue:`5863`) |
| |
| * :class:`bz2.BZ2File` and :func:`bz2.decompress` can now decompress |
| multi-stream inputs (such as those produced by the :program:`pbzip2` tool). |
| :class:`bz2.BZ2File` can now also be used to create this type of file, using |
| the ``'a'`` (append) mode. |
| |
| (Contributed by Nir Aides in :issue:`1625`) |
| |
| * :class:`bz2.BZ2File` now implements all of the :class:`io.BufferedIOBase` API, |
| except for the :meth:`detach` and :meth:`truncate` methods. |
| |
| |
| codecs |
| ------ |
| |
| The :mod:`~encodings.mbcs` codec has been rewritten to handle correctly |
| ``replace`` and ``ignore`` error handlers on all Windows versions. The |
| :mod:`~encodings.mbcs` codec now supports all error handlers, instead of only |
| ``replace`` to encode and ``ignore`` to decode. |
| |
| A new Windows-only codec has been added: ``cp65001`` (:issue:`13216`). It is the |
| Windows code page 65001 (Windows UTF-8, ``CP_UTF8``). For example, it is used |
| by ``sys.stdout`` if the console output code page is set to cp65001 (e.g., using |
| ``chcp 65001`` command). |
| |
| Multibyte CJK decoders now resynchronize faster. They only ignore the first |
| byte of an invalid byte sequence. For example, ``b'\xff\n'.decode('gb2312', |
| 'replace')`` now returns a ``\n`` after the replacement character. |
| |
| (:issue:`12016`) |
| |
| Incremental CJK codec encoders are no longer reset at each call to their |
| encode() methods. For example:: |
| |
| $ ./python -q |
| >>> import codecs |
| >>> encoder = codecs.getincrementalencoder('hz')('strict') |
| >>> b''.join(encoder.encode(x) for x in '\u52ff\u65bd\u65bc\u4eba\u3002 Bye.') |
| b'~{NpJ)l6HK!#~} Bye.' |
| |
| This example gives ``b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~} Bye.'`` with older Python |
| versions. |
| |
| (:issue:`12100`) |
| |
| The ``unicode_internal`` codec has been deprecated. |
| |
| crypt |
| ----- |
| |
| Addition of salt and modular crypt format and the :func:`~crypt.mksalt` |
| function to the :mod:`crypt` module. |
| |
| (:issue:`10924`) |
| |
| curses |
| ------ |
| |
| * If the :mod:`curses` module is linked to the ncursesw library, use Unicode |
| functions when Unicode strings or characters are passed (e.g. |
| :c:func:`waddwstr`), and bytes functions otherwise (e.g. :c:func:`waddstr`). |
| * Use the locale encoding instead of ``utf-8`` to encode Unicode strings. |
| * :class:`curses.window` has a new :attr:`curses.window.encoding` attribute. |
| * The :class:`curses.window` class has a new :meth:`~curses.window.get_wch` |
| method to get a wide character |
| * The :mod:`curses` module has a new :meth:`~curses.unget_wch` function to |
| push a wide character so the next :meth:`~curses.window.get_wch` will return |
| it |
| |
| (Contributed by Iñigo Serna in :issue:`6755`) |
| |
| decimal |
| ------- |
| |
| :issue:`7652` - integrate fast native decimal arithmetic. |
| C-module and libmpdec written by Stefan Krah. |
| |
| The new C version of the decimal module integrates the high speed libmpdec |
| library for arbitrary precision correctly-rounded decimal floating point |
| arithmetic. libmpdec conforms to IBM's General Decimal Arithmetic Specification. |
| |
| Performance gains range from 10x for database applications to 80x for |
| numerically intensive applications. These numbers are expected gains |
| for standard precisions used in decimal floating point arithmetic. Since |
| the precision is user configurable, the exact figures may vary. For example, |
| in integer bignum arithmetic the differences can be significantly higher. |
| |
| The following table is meant as an illustration. Benchmarks are available |
| at http://www.bytereef.org/mpdecimal/quickstart.html. |
| |
| +---------+-------------+--------------+-------------+ |
| | | decimal.py | _decimal | speedup | |
| +=========+=============+==============+=============+ |
| | pi | 42.75s | 0.58s | 74x | |
| +---------+-------------+--------------+-------------+ |
| | telco | 172.19s | 5.68s | 30x | |
| +---------+-------------+--------------+-------------+ |
| | psycopg | 3.57s | 0.29s | 12x | |
| +---------+-------------+--------------+-------------+ |
| |
| Features |
| ~~~~~~~~ |
| |
| * The :exc:`~decimal.FloatOperation` signal optionally enables stricter |
| semantics for mixing floats and Decimals. |
| |
| * If Python is compiled without threads, the C version automatically |
| disables the expensive thread local context machinery. In this case, |
| the variable :data:`~decimal.HAVE_THREADS` is set to False. |
| |
| API changes |
| ~~~~~~~~~~~ |
| |
| * The C module has the following context limits, depending on the machine |
| architecture: |
| |
| +-------------------+---------------------+------------------------------+ |
| | | 32-bit | 64-bit | |
| +===================+=====================+==============================+ |
| | :const:`MAX_PREC` | :const:`425000000` | :const:`999999999999999999` | |
| +-------------------+---------------------+------------------------------+ |
| | :const:`MAX_EMAX` | :const:`425000000` | :const:`999999999999999999` | |
| +-------------------+---------------------+------------------------------+ |
| | :const:`MIN_EMIN` | :const:`-425000000` | :const:`-999999999999999999` | |
| +-------------------+---------------------+------------------------------+ |
| |
| * In the context templates (:class:`~decimal.DefaultContext`, |
| :class:`~decimal.BasicContext` and :class:`~decimal.ExtendedContext`) |
| the magnitude of :attr:`~decimal.Context.Emax` and |
| :attr:`~decimal.Context.Emin` has changed to :const:`999999`. |
| |
| * The :class:`~decimal.Decimal` constructor in decimal.py does not observe |
| the context limits and converts values with arbitrary exponents or precision |
| exactly. Since the C version has internal limits, the following scheme is |
| used: If possible, values are converted exactly, otherwise |
| :exc:`~decimal.InvalidOperation` is raised and the result is NaN. In the |
| latter case it is always possible to use :meth:`~decimal.Context.create_decimal` |
| in order to obtain a rounded or inexact value. |
| |
| |
| * The power function in decimal.py is always correctly-rounded. In the |
| C version, it is defined in terms of the correctly-rounded |
| :meth:`~decimal.Decimal.exp` and :meth:`~decimal.Decimal.ln` functions, |
| but the final result is only "almost always correctly rounded". |
| |
| |
| * In the C version, the context dictionary containing the signals is a |
| :class:`~collections.abc.MutableMapping`. For speed reasons, |
| :attr:`~decimal.Context.flags` and :attr:`~decimal.Context.traps` always |
| refer to the same :class:`~collections.abc.MutableMapping` that the context |
| was initialized with. If a new signal dictionary is assigned, |
| :attr:`~decimal.Context.flags` and :attr:`~decimal.Context.traps` |
| are updated with the new values, but they do not reference the RHS |
| dictionary. |
| |
| |
| * Pickling a :class:`~decimal.Context` produces a different output in order |
| to have a common interchange format for the Python and C versions. |
| |
| |
| * The order of arguments in the :class:`~decimal.Context` constructor has been |
| changed to match the order displayed by :func:`repr`. |
| |
| |
| faulthandler |
| ------------ |
| |
| New module: :mod:`faulthandler`. |
| |
| * :envvar:`PYTHONFAULTHANDLER` |
| * :option:`-X` ``faulthandler`` |
| |
| ftplib |
| ------ |
| |
| The :class:`~ftplib.FTP_TLS` class now provides a new |
| :func:`~ftplib.FTP_TLS.ccc` function to revert control channel back to |
| plaintext. This can be useful to take advantage of firewalls that know how to |
| handle NAT with non-secure FTP without opening fixed ports. |
| |
| (Contributed by Giampaolo Rodolà in :issue:`12139`) |
| |
| |
| imaplib |
| ------- |
| |
| The :class:`~imaplib.IMAP4_SSL` constructor now accepts an SSLContext |
| parameter to control parameters of the secure channel. |
| |
| (Contributed by Sijin Joseph in :issue:`8808`) |
| |
| |
| io |
| -- |
| |
| The :func:`~io.open` function has a new ``'x'`` mode that can be used to |
| exclusively create a new file, and raise a :exc:`FileExistsError` if the file |
| already exists. It is based on the C11 'x' mode to fopen(). |
| |
| (Contributed by David Townshend in :issue:`12760`) |
| |
| |
| lzma |
| ---- |
| |
| The newly-added :mod:`lzma` module provides data compression and decompression |
| using the LZMA algorithm, including support for the ``.xz`` and ``.lzma`` |
| file formats. |
| |
| (Contributed by Nadeem Vawda and Per Øyvind Karlsen in :issue:`6715`) |
| |
| |
| math |
| ---- |
| |
| The :mod:`math` module has a new function: |
| |
| * :func:`~math.log2`: return the base-2 logarithm of *x* |
| (Written by Mark Dickinson in :issue:`11888`). |
| |
| |
| nntplib |
| ------- |
| |
| The :class:`nntplib.NNTP` class now supports the context manager protocol to |
| unconditionally consume :exc:`socket.error` exceptions and to close the NNTP |
| connection when done:: |
| |
| >>> from nntplib import NNTP |
| >>> with NNTP('news.gmane.org') as n: |
| ... n.group('gmane.comp.python.committers') |
| ... |
| ('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.python.committers') |
| >>> |
| |
| (Contributed by Giampaolo Rodolà in :issue:`9795`) |
| |
| |
| os |
| -- |
| |
| * The :mod:`os` module has a new :func:`~os.pipe2` function that makes it |
| possible to create a pipe with :data:`~os.O_CLOEXEC` or |
| :data:`~os.O_NONBLOCK` flags set atomically. This is especially useful to |
| avoid race conditions in multi-threaded programs. |
| |
| * The :mod:`os` module has a new :func:`~os.sendfile` function which provides |
| an efficent "zero-copy" way for copying data from one file (or socket) |
| descriptor to another. The phrase "zero-copy" refers to the fact that all of |
| the copying of data between the two descriptors is done entirely by the |
| kernel, with no copying of data into userspace buffers. :func:`~os.sendfile` |
| can be used to efficiently copy data from a file on disk to a network socket, |
| e.g. for downloading a file. |
| |
| (Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.) |
| |
| * The :mod:`os` module has two new functions: :func:`~os.getpriority` and |
| :func:`~os.setpriority`. They can be used to get or set process |
| niceness/priority in a fashion similar to :func:`os.nice` but extended to all |
| processes instead of just the current one. |
| |
| (Patch submitted by Giampaolo Rodolà in :issue:`10784`.) |
| |
| * The :mod:`os` module has a new :func:`~os.fwalk` function similar to |
| :func:`~os.walk` except that it also yields file descriptors referring to the |
| directories visited. This is especially useful to avoid symlink races. |
| |
| * "at" functions (:issue:`4761`): |
| |
| * :func:`~os.faccessat` |
| * :func:`~os.fchmodat` |
| * :func:`~os.fchownat` |
| * :func:`~os.fstatat` |
| * :func:`~os.futimesat` |
| * :func:`~os.linkat` |
| * :func:`~os.mkdirat` |
| * :func:`~os.mkfifoat` |
| * :func:`~os.mknodat` |
| * :func:`~os.openat` |
| * :func:`~os.readlinkat` |
| * :func:`~os.renameat` |
| * :func:`~os.symlinkat` |
| * :func:`~os.unlinkat` |
| * :func:`~os.utimensat` |
| |
| * extended attributes (:issue:`12720`): |
| |
| * :func:`~os.fgetxattr` |
| * :func:`~os.flistxattr` |
| * :func:`~os.fremovexattr` |
| * :func:`~os.fsetxattr` |
| * :func:`~os.getxattr` |
| * :func:`~os.lgetxattr` |
| * :func:`~os.listxattr` |
| * :func:`~os.llistxattr` |
| * :func:`~os.lremovexattr` |
| * :func:`~os.lsetxattr` |
| * :func:`~os.removexattr` |
| * :func:`~os.setxattr` |
| |
| * Scheduler functions (:issue:`12655`): |
| |
| * :func:`~os.sched_get_priority_max` |
| * :func:`~os.sched_get_priority_min` |
| * :func:`~os.sched_getaffinity` |
| * :func:`~os.sched_getparam` |
| * :func:`~os.sched_getscheduler` |
| * :func:`~os.sched_rr_get_interval` |
| * :func:`~os.sched_setaffinity` |
| * :func:`~os.sched_setparam` |
| * :func:`~os.sched_setscheduler` |
| * :func:`~os.sched_yield` |
| |
| * Add some extra posix functions to the os module (:issue:`10812`): |
| |
| * :func:`~os.fexecve` |
| * :func:`~os.futimens` |
| * :func:`~os.futimes` |
| * :func:`~os.lockf` |
| * :func:`~os.lutimes` |
| * :func:`~os.posix_fadvise` |
| * :func:`~os.posix_fallocate` |
| * :func:`~os.pread` |
| * :func:`~os.pwrite` |
| * :func:`~os.readv` |
| * :func:`~os.sync` |
| * :func:`~os.truncate` |
| * :func:`~os.waitid` |
| * :func:`~os.writev` |
| |
| * Other new functions: |
| |
| * :func:`~os.flistdir` (:issue:`10755`) |
| * :func:`~os.getgrouplist` (:issue:`9344`) |
| |
| |
| packaging |
| --------- |
| |
| :mod:`distutils` has undergone additions and refactoring under a new name, |
| :mod:`packaging`, to allow developers to break backward compatibility. |
| :mod:`distutils` is still provided in the standard library, but users are |
| encouraged to transition to :mod:`packaging`. For older versions of Python, a |
| backport compatible with 2.4+ and 3.1+ will be made available on PyPI under the |
| name :mod:`distutils2`. |
| |
| .. TODO add examples and howto to the packaging docs and link to them |
| |
| |
| pdb |
| --- |
| |
| * Tab-completion is now available not only for command names, but also their |
| arguments. For example, for the ``break`` command, function and file names |
| are completed. (Contributed by Georg Brandl in :issue:`14210`) |
| |
| |
| pydoc |
| ----- |
| |
| The Tk GUI and the :func:`~pydoc.serve` function have been removed from the |
| :mod:`pydoc` module: ``pydoc -g`` and :func:`~pydoc.serve` have been deprecated |
| in Python 3.2. |
| |
| |
| sched |
| ----- |
| |
| * :meth:`~sched.scheduler.run` now accepts a *blocking* parameter which when |
| set to False makes the method execute the scheduled events due to expire |
| soonest (if any) and then return immediately. |
| This is useful in case you want to use the :class:`~sched.scheduler` in |
| non-blocking applications. (Contributed by Giampaolo Rodolà in :issue:`13449`) |
| |
| * :class:`~sched.scheduler` class can now be safely used in multi-threaded |
| environments. (Contributed by Josiah Carlson and Giampaolo Rodolà in |
| :issue:`8684`) |
| |
| * *timefunc* and *delayfunct* parameters of :class:`~sched.scheduler` class |
| constructor are now optional and defaults to :func:`time.time` and |
| :func:`time.sleep` respectively. (Contributed by Chris Clark in |
| :issue:`13245`) |
| |
| * :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs` |
| *argument* parameter is now optional. (Contributed by Chris Clark in |
| :issue:`13245`) |
| |
| * :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs` |
| now accept a *kwargs* parameter. (Contributed by Chris Clark in |
| :issue:`13245`) |
| |
| |
| shutil |
| ------ |
| |
| * The :mod:`shutil` module has these new fuctions: |
| |
| * :func:`~shutil.disk_usage`: provides total, used and free disk space |
| statistics. (Contributed by Giampaolo Rodolà in :issue:`12442`) |
| * :func:`~shutil.chown`: allows one to change user and/or group of the given |
| path also specifying the user/group names and not only their numeric |
| ids. (Contributed by Sandro Tosi in :issue:`12191`) |
| |
| |
| signal |
| ------ |
| |
| * The :mod:`signal` module has new functions: |
| |
| * :func:`~signal.pthread_sigmask`: fetch and/or change the signal mask of the |
| calling thread (Contributed by Jean-Paul Calderone in :issue:`8407`) ; |
| * :func:`~signal.pthread_kill`: send a signal to a thread ; |
| * :func:`~signal.sigpending`: examine pending functions ; |
| * :func:`~signal.sigwait`: wait a signal. |
| * :func:`~signal.sigwaitinfo`: wait for a signal, returning detailed |
| information about it. |
| * :func:`~signal.sigtimedwait`: like :func:`~signal.sigwaitinfo` but with a |
| timeout. |
| |
| * The signal handler writes the signal number as a single byte instead of |
| a nul byte into the wakeup file descriptor. So it is possible to wait more |
| than one signal and know which signals were raised. |
| |
| * :func:`signal.signal` and :func:`signal.siginterrupt` raise an OSError, |
| instead of a RuntimeError: OSError has an errno attribute. |
| |
| smtplib |
| ------- |
| |
| The :class:`~smtplib.SMTP_SSL` constructor and the :meth:`~smtplib.SMTP.starttls` |
| method now accept an SSLContext parameter to control parameters of the secure |
| channel. |
| |
| (Contributed by Kasun Herath in :issue:`8809`) |
| |
| |
| socket |
| ------ |
| |
| * The :class:`~socket.socket` class now exposes additional methods to process |
| ancillary data when supported by the underlying platform: |
| |
| * :func:`~socket.socket.sendmsg` |
| * :func:`~socket.socket.recvmsg` |
| * :func:`~socket.socket.recvmsg_into` |
| |
| (Contributed by David Watson in :issue:`6560`, based on an earlier patch by |
| Heiko Wundram) |
| |
| * The :class:`~socket.socket` class now supports the PF_CAN protocol family |
| (http://en.wikipedia.org/wiki/Socketcan), on Linux |
| (http://lwn.net/Articles/253425). |
| |
| (Contributed by Matthias Fuchs, updated by Tiago Gonçalves in :issue:`10141`) |
| |
| * The :class:`~socket.socket` class now supports the PF_RDS protocol family |
| (http://en.wikipedia.org/wiki/Reliable_Datagram_Sockets and |
| http://oss.oracle.com/projects/rds/). |
| |
| |
| ssl |
| --- |
| |
| * The :mod:`ssl` module has two new random generation functions: |
| |
| * :func:`~ssl.RAND_bytes`: generate cryptographically strong |
| pseudo-random bytes. |
| * :func:`~ssl.RAND_pseudo_bytes`: generate pseudo-random bytes. |
| |
| (Contributed by Victor Stinner in :issue:`12049`) |
| |
| * The :mod:`ssl` module now exposes a finer-grained exception hierarchy |
| in order to make it easier to inspect the various kinds of errors. |
| |
| (Contributed by Antoine Pitrou in :issue:`11183`) |
| |
| * :meth:`~ssl.SSLContext.load_cert_chain` now accepts a *password* argument |
| to be used if the private key is encrypted. |
| |
| (Contributed by Adam Simpkins in :issue:`12803`) |
| |
| * Diffie-Hellman key exchange, both regular and Elliptic Curve-based, is |
| now supported through the :meth:`~ssl.SSLContext.load_dh_params` and |
| :meth:`~ssl.SSLContext.set_ecdh_curve` methods. |
| |
| (Contributed by Antoine Pitrou in :issue:`13626` and :issue:`13627`) |
| |
| * SSL sockets have a new :meth:`~ssl.SSLSocket.get_channel_binding` method |
| allowing the implementation of certain authentication mechanisms such as |
| SCRAM-SHA-1-PLUS. |
| |
| (Contributed by Jacek Konieczny in :issue:`12551`) |
| |
| * You can query the SSL compression algorithm used by an SSL socket, thanks |
| to its new :meth:`~ssl.SSLSocket.compression` method. |
| |
| (Contributed by Antoine Pitrou in :issue:`13634`) |
| |
| |
| sys |
| --- |
| |
| * The :mod:`sys` module has a new :data:`~sys.thread_info` :term:`struct |
| sequence` holding informations about the thread implementation. |
| |
| (:issue:`11223`) |
| |
| |
| time |
| ---- |
| |
| The :mod:`time` module has new functions: |
| |
| * :func:`~time.clock_getres` and :func:`~time.clock_gettime` functions and |
| ``CLOCK_xxx`` constants. |
| * :func:`~time.steady`. |
| |
| (Contributed by Victor Stinner in :issue:`10278`) |
| |
| |
| urllib |
| ------ |
| |
| The :class:`~urllib.request.Request` class, now accepts a *method* argument |
| used by :meth:`~urllib.request.Request.get_method` to determine what HTTP method |
| should be used. For example, this will send a ``'HEAD'`` request:: |
| |
| >>> urlopen(Request('http://www.python.org', method='HEAD')) |
| |
| (:issue:`1673007`) |
| |
| |
| Optimizations |
| ============= |
| |
| Major performance enhancements have been added: |
| |
| * Thanks to the :pep:`393`, some operations on Unicode strings has been optimized: |
| |
| * the memory footprint is divided by 2 to 4 depending on the text |
| * encode an ASCII string to UTF-8 doesn't need to encode characters anymore, |
| the UTF-8 representation is shared with the ASCII representation |
| * the UTF-8 encoder has been optimized |
| * repeating a single ASCII letter and getting a substring of a ASCII strings |
| is 4 times faster |
| |
| |
| Build and C API Changes |
| ======================= |
| |
| Changes to Python's build process and to the C API include: |
| |
| * New :pep:`3118` related function: |
| |
| * :c:func:`PyMemoryView_FromMemory` |
| |
| * The :pep:`393` added new Unicode types, macros and functions: |
| |
| * High-level API: |
| |
| * :c:func:`PyUnicode_CopyCharacters` |
| * :c:func:`PyUnicode_FindChar` |
| * :c:func:`PyUnicode_GetLength`, :c:macro:`PyUnicode_GET_LENGTH` |
| * :c:func:`PyUnicode_New` |
| * :c:func:`PyUnicode_Substring` |
| * :c:func:`PyUnicode_ReadChar`, :c:func:`PyUnicode_WriteChar` |
| |
| * Low-level API: |
| |
| * :c:type:`Py_UCS1`, :c:type:`Py_UCS2`, :c:type:`Py_UCS4` types |
| * :c:type:`PyASCIIObject` and :c:type:`PyCompactUnicodeObject` structures |
| * :c:macro:`PyUnicode_READY` |
| * :c:func:`PyUnicode_FromKindAndData` |
| * :c:func:`PyUnicode_AsUCS4`, :c:func:`PyUnicode_AsUCS4Copy` |
| * :c:macro:`PyUnicode_DATA`, :c:macro:`PyUnicode_1BYTE_DATA`, |
| :c:macro:`PyUnicode_2BYTE_DATA`, :c:macro:`PyUnicode_4BYTE_DATA` |
| * :c:macro:`PyUnicode_KIND` with :c:type:`PyUnicode_Kind` enum: |
| :c:data:`PyUnicode_WCHAR_KIND`, :c:data:`PyUnicode_1BYTE_KIND`, |
| :c:data:`PyUnicode_2BYTE_KIND`, :c:data:`PyUnicode_4BYTE_KIND` |
| * :c:macro:`PyUnicode_READ`, :c:macro:`PyUnicode_READ_CHAR`, :c:macro:`PyUnicode_WRITE` |
| * :c:macro:`PyUnicode_MAX_CHAR_VALUE` |
| |
| |
| |
| Deprecated |
| ========== |
| |
| Unsupported Operating Systems |
| ----------------------------- |
| |
| OS/2 and VMS are no longer supported due to the lack of a maintainer. |
| |
| Windows 2000 and Windows platforms which set ``COMSPEC`` to ``command.com`` |
| are no longer supported due to maintenance burden. |
| |
| |
| Deprecated Python modules, functions and methods |
| ------------------------------------------------ |
| |
| * The :mod:`distutils` modules has been deprecated. Use the new |
| :mod:`packaging` module instead. |
| * The ``unicode_internal`` codec has been deprecated because of the |
| :pep:`393`, use UTF-8, UTF-16 (``utf-16-le`` or ``utf-16-be``), or UTF-32 |
| (``utf-32-le`` or ``utf-32-be``) |
| * :meth:`ftplib.FTP.nlst` and :meth:`ftplib.FTP.dir`: use |
| :meth:`ftplib.FTP.mlsd` |
| * :func:`platform.popen`: use the :mod:`subprocess` module. Check especially |
| the :ref:`subprocess-replacements` section. |
| * :issue:`13374`: The Windows bytes API has been deprecated in the :mod:`os` |
| module. Use Unicode filenames, instead of bytes filenames, to not depend on |
| the ANSI code page anymore and to support any filename. |
| * :issue:`13988`: The :mod:`xml.etree.cElementTree` module is deprecated. The |
| accelerator is used automatically whenever available. |
| |
| |
| Deprecated functions and types of the C API |
| ------------------------------------------- |
| |
| The :c:type:`Py_UNICODE` has been deprecated by the :pep:`393` and will be |
| removed in Python 4. All functions using this type are deprecated: |
| |
| Unicode functions and methods using :c:type:`Py_UNICODE` and |
| :c:type:`Py_UNICODE*` types: |
| |
| * :c:macro:`PyUnicode_FromUnicode`: use :c:func:`PyUnicode_FromWideChar` or |
| :c:func:`PyUnicode_FromKindAndData` |
| * :c:macro:`PyUnicode_AS_UNICODE`, :c:func:`PyUnicode_AsUnicode`, |
| :c:func:`PyUnicode_AsUnicodeAndSize`: use :c:func:`PyUnicode_AsWideCharString` |
| * :c:macro:`PyUnicode_AS_DATA`: use :c:macro:`PyUnicode_DATA` with |
| :c:macro:`PyUnicode_READ` and :c:macro:`PyUnicode_WRITE` |
| * :c:macro:`PyUnicode_GET_SIZE`, :c:func:`PyUnicode_GetSize`: use |
| :c:macro:`PyUnicode_GET_LENGTH` or :c:func:`PyUnicode_GetLength` |
| * :c:macro:`PyUnicode_GET_DATA_SIZE`: use |
| ``PyUnicode_GET_LENGTH(str) * PyUnicode_KIND(str)`` (only work on ready |
| strings) |
| * :c:func:`PyUnicode_AsUnicodeCopy`: use :c:func:`PyUnicode_AsUCS4Copy` or |
| :c:func:`PyUnicode_AsWideCharString` |
| * :c:func:`PyUnicode_GetMax` |
| |
| |
| Functions and macros manipulating Py_UNICODE* strings: |
| |
| * :c:macro:`Py_UNICODE_strlen`: use :c:func:`PyUnicode_GetLength` or |
| :c:macro:`PyUnicode_GET_LENGTH` |
| * :c:macro:`Py_UNICODE_strcat`: use :c:func:`PyUnicode_CopyCharacters` or |
| :c:func:`PyUnicode_FromFormat` |
| * :c:macro:`Py_UNICODE_strcpy`, :c:macro:`Py_UNICODE_strncpy`, |
| :c:macro:`Py_UNICODE_COPY`: use :c:func:`PyUnicode_CopyCharacters` or |
| :c:func:`PyUnicode_Substring` |
| * :c:macro:`Py_UNICODE_strcmp`: use :c:func:`PyUnicode_Compare` |
| * :c:macro:`Py_UNICODE_strncmp`: use :c:func:`PyUnicode_Tailmatch` |
| * :c:macro:`Py_UNICODE_strchr`, :c:macro:`Py_UNICODE_strrchr`: use |
| :c:func:`PyUnicode_FindChar` |
| * :c:macro:`Py_UNICODE_FILL`: use :c:func:`PyUnicode_Fill` |
| * :c:macro:`Py_UNICODE_MATCH` |
| |
| Encoders: |
| |
| * :c:func:`PyUnicode_Encode`: use :c:func:`PyUnicode_AsEncodedObject` |
| * :c:func:`PyUnicode_EncodeUTF7` |
| * :c:func:`PyUnicode_EncodeUTF8`: use :c:func:`PyUnicode_AsUTF8` or |
| :c:func:`PyUnicode_AsUTF8String` |
| * :c:func:`PyUnicode_EncodeUTF32` |
| * :c:func:`PyUnicode_EncodeUTF16` |
| * :c:func:`PyUnicode_EncodeUnicodeEscape:` use |
| :c:func:`PyUnicode_AsUnicodeEscapeString` |
| * :c:func:`PyUnicode_EncodeRawUnicodeEscape:` use |
| :c:func:`PyUnicode_AsRawUnicodeEscapeString` |
| * :c:func:`PyUnicode_EncodeLatin1`: use :c:func:`PyUnicode_AsLatin1String` |
| * :c:func:`PyUnicode_EncodeASCII`: use :c:func:`PyUnicode_AsASCIIString` |
| * :c:func:`PyUnicode_EncodeCharmap` |
| * :c:func:`PyUnicode_TranslateCharmap` |
| * :c:func:`PyUnicode_EncodeMBCS`: use :c:func:`PyUnicode_AsMBCSString` or |
| :c:func:`PyUnicode_EncodeCodePage` (with ``CP_ACP`` code_page) |
| * :c:func:`PyUnicode_EncodeDecimal`, |
| :c:func:`PyUnicode_TransformDecimalToASCII` |
| |
| |
| Porting to Python 3.3 |
| ===================== |
| |
| This section lists previously described changes and other bugfixes |
| that may require changes to your code. |
| |
| Porting Python code |
| ------------------- |
| |
| .. XXX add a point about hash randomization and that it's always on in 3.3 |
| |
| * :issue:`14205`: A dict lookup now raises a :exc:`RuntimeError` if the dict is |
| modified during the lookup. If you implement your own comparison function for |
| objects used as dict keys and the dict is shared by multiple threads, access |
| to the dict should be protected by a lock. |
| |
| * :issue:`12326`: On Linux, sys.platform doesn't contain the major version |
| anymore. It is now always 'linux', instead of 'linux2' or 'linux3' depending |
| on the Linux version used to build Python. Replace sys.platform == 'linux2' |
| with sys.platform.startswith('linux'), or directly sys.platform == 'linux' if |
| you don't need to support older Python versions. |
| |
| * :issue:`13847`, :issue:`14180`: :mod:`time` and :mod:`datetime`: |
| :exc:`OverflowError` is now raised instead of :exc:`ValueError` if a |
| timestamp is out of range. :exc:`OSError` is now raised if C functions |
| :c:func:`gmtime` or :c:func:`localtime` failed. |
| |
| Porting C code |
| -------------- |
| |
| * In the course of changes to the buffer API the undocumented |
| :c:member:`~Py_buffer.smalltable` member of the |
| :c:type:`Py_buffer` structure has been removed and the |
| layout of the :c:type:`PyMemoryViewObject` has changed. |
| |
| All extensions relying on the relevant parts in ``memoryobject.h`` |
| or ``object.h`` must be rebuilt. |
| |
| * Due to :ref:`PEP 393 <pep-393>`, the :c:type:`Py_UNICODE` type and all |
| functions using this type are deprecated (but will stay available for |
| at least five years). If you were using low-level Unicode APIs to |
| construct and access unicode objects and you want to benefit of the |
| memory footprint reduction provided by the PEP 393, you have to convert |
| your code to the new :doc:`Unicode API <../c-api/unicode>`. |
| |
| However, if you only have been using high-level functions such as |
| :c:func:`PyUnicode_Concat()`, :c:func:`PyUnicode_Join` or |
| :c:func:`PyUnicode_FromFormat()`, your code will automatically take |
| advantage of the new unicode representations. |
| |
| Building C extensions |
| --------------------- |
| |
| * The range of possible file names for C extensions has been narrowed. |
| Very rarely used spellings have been suppressed: under POSIX, files |
| named ``xxxmodule.so``, ``xxxmodule.abi3.so`` and |
| ``xxxmodule.cpython-*.so`` are no longer recognized as implementing |
| the ``xxx`` module. If you had been generating such files, you have |
| to switch to the other spellings (i.e., remove the ``module`` string |
| from the file names). |
| |
| (implemented in :issue:`14040`.) |
| |
| |
| Other issues |
| ------------ |
| |
| .. Issue #11591: When :program:`python` was started with :option:`-S`, |
| ``import site`` will not add site-specific paths to the module search |
| paths. In previous versions, it did. See changeset for doc changes in |
| various files. Contributed by Carl Meyer with editions by Éric Araujo. |
| |
| .. Issue #10998: the -Q command-line flag and related artifacts have been |
| removed. Code checking sys.flags.division_warning will need updating. |
| Contributed by Éric Araujo. |