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Delta Between Two Patch Sets: Doc/whatsnew/3.3.rst

Issue 11682: PEP 380 reference implementation for 3.3
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LEFTRIGHT
1 **************************** 1 ****************************
2 What's New In Python 3.3 2 What's New In Python 3.3
3 **************************** 3 ****************************
4 4
5 :Author: Raymond Hettinger 5 :Author: Raymond Hettinger
6 :Release: |release| 6 :Release: |release|
7 :Date: |today| 7 :Date: |today|
8 8
9 .. $Id$ 9 .. Rules for maintenance:
10 Rules for maintenance:
11 10
12 * Anyone can add text to this document. Do not spend very much time 11 * Anyone can add text to this document. Do not spend very much time
13 on the wording of your changes, because your text will probably 12 on the wording of your changes, because your text will probably
14 get rewritten to some degree. 13 get rewritten to some degree.
15 14
16 * The maintainer will go through Misc/NEWS periodically and add 15 * The maintainer will go through Misc/NEWS periodically and add
17 changes; it's therefore more important to add your changes to 16 changes; it's therefore more important to add your changes to
18 Misc/NEWS than to this file. 17 Misc/NEWS than to this file.
19 18
20 * This is not a complete list of every single change; completeness 19 * This is not a complete list of every single change; completeness
(...skipping 12 matching lines...) Expand all
33 write the necessary text. 32 write the necessary text.
34 33
35 * You can comment out your additions if you like, but it's not 34 * You can comment out your additions if you like, but it's not
36 necessary (especially when a final release is some months away). 35 necessary (especially when a final release is some months away).
37 36
38 * Credit the author of a patch or bugfix. Just the name is 37 * Credit the author of a patch or bugfix. Just the name is
39 sufficient; the e-mail address isn't necessary. 38 sufficient; the e-mail address isn't necessary.
40 39
41 * It's helpful to add the bug/patch number as a comment: 40 * It's helpful to add the bug/patch number as a comment:
42 41
43 % Patch 12345
44 XXX Describe the transmogrify() function added to the socket 42 XXX Describe the transmogrify() function added to the socket
45 module. 43 module.
46 (Contributed by P.Y. Developer.) 44 (Contributed by P.Y. Developer in :issue:`12345`.)
47 45
48 This saves the maintainer the effort of going through the SVN log 46 This saves the maintainer the effort of going through the Mercurial log
49 when researching a change. 47 when researching a change.
50 48
51 This article explains the new features in Python 3.3, compared to 3.2. 49 This article explains the new features in Python 3.3, compared to 3.2.
52 50
53 51
54 PEP XXX: Stub 52 .. _pep-393:
55 ============= 53
54 PEP 393: Flexible String Representation
55 =======================================
56
57 The Unicode string type is changed to support multiple internal
58 representations, depending on the character with the largest Unicode ordinal
59 (1, 2, or 4 bytes) in the represented string. This allows a space-efficient
60 representation in common cases, but gives access to full UCS-4 on all
61 systems. For compatibility with existing APIs, several representations may
62 exist in parallel; over time, this compatibility should be phased out.
63
64 On the Python side, there should be no downside to this change.
65
66 On the C API side, PEP 393 is fully backward compatible. The legacy API
67 should remain available at least five years. Applications using the legacy
68 API will not fully benefit of the memory reduction, or - worse - may use
69 a bit more memory, because Python may have to maintain two versions of each
70 string (in the legacy format and in the new efficient storage).
71
72 Functionality
73 -------------
74
75 Changes introduced by :pep:`393` are the following:
76
77 * Python now always supports the full range of Unicode codepoints, including
78 non-BMP ones (i.e. from ``U+0000`` to ``U+10FFFF``). The distinction between
79 narrow and wide builds no longer exists and Python now behaves like a wide
80 build, even under Windows.
81
82 * With the death of narrow builds, the problems specific to narrow builds have
83 also been fixed, for example:
84
85 * :func:`len` now always returns 1 for non-BMP characters,
86 so ``len('\U0010FFFF') == 1``;
87
88 * surrogate pairs are not recombined in string literals,
89 so ``'\uDBFF\uDFFF' != '\U0010FFFF'``;
90
91 * indexing or slicing non-BMP characters returns the expected value,
92 so ``'\U0010FFFF'[0]`` now returns ``'\U0010FFFF'`` and not ``'\uDBFF'``;
93
94 * all other functions in the standard library now correctly handle
95 non-BMP codepoints.
96
97 * The value of :data:`sys.maxunicode` is now always ``1114111`` (``0x10FFFF``
98 in hexadecimal). The :c:func:`PyUnicode_GetMax` function still returns
99 either ``0xFFFF`` or ``0x10FFFF`` for backward compatibility, and it should
100 not be used with the new Unicode API (see :issue:`13054`).
101
102 * The :file:`./configure` flag ``--with-wide-unicode`` has been removed.
103
104 Performance and resource usage
105 ------------------------------
106
107 The storage of Unicode strings now depends on the highest codepoint in the strin g:
108
109 * pure ASCII and Latin1 strings (``U+0000-U+00FF``) use 1 byte per codepoint;
110
111 * BMP strings (``U+0000-U+FFFF``) use 2 bytes per codepoint;
112
113 * non-BMP strings (``U+10000-U+10FFFF``) use 4 bytes per codepoint.
114
115 The net effect is that for most applications, memory usage of string storage
116 should decrease significantly - especially compared to former wide unicode
117 builds - as, in many cases, strings will be pure ASCII even in international
118 contexts (because many strings store non-human language data, such as XML
119 fragments, HTTP headers, JSON-encoded data, etc.). We also hope that it
120 will, for the same reasons, increase CPU cache efficiency on non-trivial
121 applications.
122
123 .. The memory usage of Python 3.3 is two to three times smaller than Python 3.2,
124 and a little bit better than Python 2.7, on a `Django benchmark
125 <http://mail.python.org/pipermail/python-dev/2011-September/113714.html>`_.
126 XXX The result should be moved in the PEP and a link to the PEP should
127 be added here.
128
129
130 PEP 3151: Reworking the OS and IO exception hierarchy
131 =====================================================
132
133 :pep:`3151` - Reworking the OS and IO exception hierarchy
134 PEP written and implemented by Antoine Pitrou.
135
136 The hierarchy of exceptions raised by operating system errors is now both
137 simplified and finer-grained.
138
139 You don't have to worry anymore about choosing the appropriate exception
140 type between :exc:`OSError`, :exc:`IOError`, :exc:`EnvironmentError`,
141 :exc:`WindowsError`, :exc:`mmap.error`, :exc:`socket.error` or
142 :exc:`select.error`. All these exception types are now only one:
143 :exc:`OSError`. The other names are kept as aliases for compatibility
144 reasons.
145
146 Also, it is now easier to catch a specific error condition. Instead of
147 inspecting the ``errno`` attribute (or ``args[0]``) for a particular
148 constant from the :mod:`errno` module, you can catch the adequate
149 :exc:`OSError` subclass. The available subclasses are the following:
150
151 * :exc:`BlockingIOError`
152 * :exc:`ChildProcessError`
153 * :exc:`ConnectionError`
154 * :exc:`FileExistsError`
155 * :exc:`FileNotFoundError`
156 * :exc:`InterruptedError`
157 * :exc:`IsADirectoryError`
158 * :exc:`NotADirectoryError`
159 * :exc:`PermissionError`
160 * :exc:`ProcessLookupError`
161 * :exc:`TimeoutError`
162
163 And the :exc:`ConnectionError` itself has finer-grained subclasses:
164
165 * :exc:`BrokenPipeError`
166 * :exc:`ConnectionAbortedError`
167 * :exc:`ConnectionRefusedError`
168 * :exc:`ConnectionResetError`
169
170 Thanks to the new exceptions, common usages of the :mod:`errno` can now be
171 avoided. For example, the following code written for Python 3.2::
172
173 from errno import ENOENT, EACCES, EPERM
174
175 try:
176 with open("document.txt") as f:
177 content = f.read()
178 except IOError as err:
179 if err.errno == ENOENT:
180 print("document.txt file is missing")
181 elif err.errno in (EACCES, EPERM):
182 print("You are not allowed to read document.txt")
183 else:
184 raise
185
186 can now be written without the :mod:`errno` import and without manual
187 inspection of exception attributes::
188
189 try:
190 with open("document.txt") as f:
191 content = f.read()
192 except FileNotFoundError:
193 print("document.txt file is missing")
194 except PermissionError:
195 print("You are not allowed to read document.txt")
56 196
57 197
58 PEP 380: Syntax for Delegating to a Subgenerator 198 PEP 380: Syntax for Delegating to a Subgenerator
59 ================================================ 199 ================================================
60 200
61 PEP 380 adds the ``yield from`` expression, allowing a generator to delegate 201 PEP 380 adds the ``yield from`` expression, allowing a generator to delegate
62 part of its operations to another generator. This allows a section of code 202 part of its operations to another generator. This allows a section of code
63 containing 'yield' to be factored out and placed in another generator. 203 containing 'yield' to be factored out and placed in another generator.
64 Additionally, the subgenerator is allowed to return with a value, and the 204 Additionally, the subgenerator is allowed to return with a value, and the
65 value is made available to the delegating generator. 205 value is made available to the delegating generator.
66
67 While designed primarily for use in delegating to a subgenerator, the ``yield 206 While designed primarily for use in delegating to a subgenerator, the ``yield
68 from`` expression actually allows delegation to arbitrary subiterators. 207 from`` expression actually allows delegation to arbitrary subiterators.
69 208
70 (Implementation by Greg Ewing and Renauld Blanch) 209 (Implementation by Greg Ewing, integrated into 3.3 by Renaud Blanch, Ryan
210 Kelly and Nick Coghlan, documentation by Zbigniew Jędrzejewski-Szmek and
211 Nick Coghlan)
212
213
214 PEP 3155: Qualified name for classes and functions
215 ==================================================
216
217 :pep:`3155` - Qualified name for classes and functions
218 PEP written and implemented by Antoine Pitrou.
219
220 Functions and class objects have a new ``__qualname__`` attribute representing
221 the "path" from the module top-level to their definition. For global functions
222 and classes, this is the same as ``__name__``. For other functions and classes,
223 it provides better information about where they were actually defined, and
224 how they might be accessible from the global scope.
225
226 Example with (non-bound) methods::
227 >>> class C:
228 ... def meth(self):
229 ... pass
230 >>> C.meth.__name__
231 'meth'
232 >>> C.meth.__qualname__
233 'C.meth'
234
235 Example with nested classes::
236
237 >>> class C:
238 ... class D:
239 ... def meth(self):
240 ... pass
241 ...
242 >>> C.D.__name__
243 'D'
244 >>> C.D.__qualname__
245 'C.D'
246 >>> C.D.meth.__name__
247 'meth'
248 >>> C.D.meth.__qualname__
249 'C.D.meth'
250
251 Example with nested functions::
252
253 >>> def outer():
254 ... def inner():
255 ... pass
256 ... return inner
257 ...
258 >>> outer().__name__
259 'inner'
260 >>> outer().__qualname__
261 'outer.<locals>.inner'
262
263 The string representation of those objects is also changed to include the
264 new, more precise information::
265
266 >>> str(C.D)
267 "<class '__main__.C.D'>"
268 >>> str(C.D.meth)
269 '<function C.D.meth at 0x7f46b9fe31e0>'
71 270
72 271
73 Other Language Changes 272 Other Language Changes
74 ====================== 273 ======================
75 274
76 Some smaller changes made to the core Python language are: 275 Some smaller changes made to the core Python language are:
77 276
78 * Stub 277 * Added support for Unicode name aliases and named sequences.
79 278 Both :func:`unicodedata.lookup()` and ``'\N{...}'`` now resolve name aliases,
80 279 and :func:`unicodedata.lookup()` resolves named sequences too.
81 New, Improved, and Deprecated Modules 280
82 ===================================== 281 (Contributed by Ezio Melotti in :issue:`12753`)
83 282
84 * Stub 283 * Equality comparisons on :func:`range` objects now return a result reflecting
284 the equality of the underlying sequences generated by those range objects.
285
286 (:issue:`13021`)
287
288 * The ``count()``, ``find()``, ``rfind()``, ``index()`` and ``rindex()``
289 methods of :class:`bytes` and :class:`bytearray` objects now accept an
290 integer between 0 and 255 as their first argument.
291
292 (:issue:`12170`)
293
294 * Memoryview objects are now hashable when the underlying object is hashable.
295
296 (Contributed by Antoine Pitrou in :issue:`13411`)
297
298
299 New and Improved Modules
300 ========================
301
302 array
303 -----
304
305 The :mod:`array` module supports the :c:type:`long long` type using ``q`` and
306 ``Q`` type codes.
307
308 (Contributed by Oren Tirosh and Hirokazu Yamamoto in :issue:`1172711`)
309
85 310
86 codecs 311 codecs
87 ------ 312 ------
313
314 The :mod:`~encodings.mbcs` codec has be rewritten to handle correclty
315 ``replace`` and ``ignore`` error handlers on all Windows versions. The
316 :mod:`~encodings.mbcs` codec is now supporting all error handlers, instead of
317 only ``replace`` to encode and ``ignore`` to decode.
318
319 A new Windows-only codec has been added: ``cp65001`` (:issue:`13216`). It is
320 the Windows code page 65001 (Windows UTF-8, ``CP_UTF8``). For example, it is
321 used by ``sys.stdout`` if the console output code page is set to cp65001 (e.g.
322 using ``chcp 65001`` command).
88 323
89 Multibyte CJK decoders now resynchronize faster. They only ignore the first 324 Multibyte CJK decoders now resynchronize faster. They only ignore the first
90 byte of an invalid byte sequence. For example, ``b'\xff\n'.decode('gb2312', 325 byte of an invalid byte sequence. For example, ``b'\xff\n'.decode('gb2312',
91 'replace')`` now returns a ``\n`` after the replacement character. 326 'replace')`` now returns a ``\n`` after the replacement character.
92 327
93 (:issue:`12016`) 328 (:issue:`12016`)
94 329
95 Don't reset incremental encoders of CJK codecs at each call to their encode() 330 Don't reset incremental encoders of CJK codecs at each call to their encode()
96 method anymore. For example:: 331 method anymore. For example::
97 332
98 $ ./python -q 333 $ ./python -q
99 >>> import codecs 334 >>> import codecs
100 >>> encoder = codecs.getincrementalencoder('hz')('strict') 335 >>> encoder = codecs.getincrementalencoder('hz')('strict')
101 >>> b''.join(encoder.encode(x) for x in '\u52ff\u65bd\u65bc\u4eba\u3002 Bye. ') 336 >>> b''.join(encoder.encode(x) for x in '\u52ff\u65bd\u65bc\u4eba\u3002 Bye. ')
102 b'~{NpJ)l6HK!#~} Bye.' 337 b'~{NpJ)l6HK!#~} Bye.'
103 338
104 This example gives ``b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~} Bye.'`` with older Python 339 This example gives ``b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~} Bye.'`` with older Python
105 versions. 340 versions.
106 341
107 (:issue:`12100`) 342 (:issue:`12100`)
108 343
344 The ``unicode_internal`` codec has been deprecated.
345
346 crypt
347 -----
348
349 Addition of salt and modular crypt format and the :func:`~crypt.mksalt`
350 function to the :mod:`crypt` module.
351
352 (:issue:`10924`)
353
354 curses
355 ------
356
357 * If the :mod:`curses` module is linked to the ncursesw library, use Unicode
358 functions when Unicode strings or characters are passed (e.g.
359 :c:func:`waddwstr`), and bytes functions otherwise (e.g. :c:func:`waddstr`).
360 * Use the locale encoding instead of ``utf-8`` to encode Unicode strings.
361 * :class:`curses.window` has a new :attr:`curses.window.encoding` attribute.
362 * The :class:`curses.window` class has a new :meth:`~curses.window.get_wch`
363 method to get a wide character
364 * The :mod:`curses` module has a new :meth:`~curses.unget_wch` function to
365 push a wide character so the next :meth:`~curses.window.get_wch` will return
366 it
367
368 (Contributed by Iñigo Serna in :issue:`6755`)
369
370 abc
371 ---
372
373 Improved support for abstract base classes containing descriptors composed with
374 abstract methods. The recommended approach to declaring abstract descriptors is
375 now to provide :attr:`__isabstractmethod__` as a dynamically updated
376 property. The built-in descriptors have been updated accordingly.
377
378 * :class:`abc.abstractproperty` has been deprecated, use :class:`property`
379 with :func:`abc.abstractmethod` instead.
380 * :class:`abc.abstractclassmethod` has been deprecated, use
381 :class:`classmethod` with :func:`abc.abstractmethod` instead.
382 * :class:`abc.abstractstaticmethod` has been deprecated, use
383 :class:`staticmethod` with :func:`abc.abstractmethod` instead.
384
385 (Contributed by Darren Dale in :issue:`11610`)
386
109 faulthandler 387 faulthandler
110 ------------ 388 ------------
111 389
112 New module: :mod:`faulthandler`. 390 New module: :mod:`faulthandler`.
113 391
114 * :envvar:`PYTHONFAULTHANDLER` 392 * :envvar:`PYTHONFAULTHANDLER`
115 * :option:`-X` ``faulthandler`` 393 * :option:`-X` ``faulthandler``
394
395 time
396 ----
397
398 * The :mod:`time` module has new :func:`~time.clock_getres` and
399 :func:`~time.clock_gettime` functions and ``CLOCK_xxx`` constants.
400 :func:`~time.clock_gettime` can be used with :data:`time.CLOCK_MONOTONIC` to
401 get a monotonic clock.
402
403 (Contributed by Victor Stinner in :issue:`10278`)
404
405
406 ftplib
407 ------
408
409 The :class:`~ftplib.FTP_TLS` class now provides a new
410 :func:`~ftplib.FTP_TLS.ccc` function to revert control channel back to
411 plaintext. This can be useful to take advantage of firewalls that know how to
412 handle NAT with non-secure FTP without opening fixed ports.
413
414 (Contributed by Giampaolo Rodolà in :issue:`12139`)
415
416
417 imaplib
418 -------
419
420 The :class:`~imaplib.IMAP4_SSL` constructor now accepts an SSLContext
421 parameter to control parameters of the secure channel.
422
423 (Contributed by Sijin Joseph in :issue:`8808`)
424
425
426 io
427 --
428
429 The :func:`~io.open` function has a new ``'x'`` mode that can be used to create
430 a new file, and raise a :exc:`FileExistsError` if the file already exists.
431
432 (Contributed by David Townshend in :issue:`12760`)
433
434
435 lzma
436 ----
437
438 The newly-added :mod:`lzma` module provides data compression and decompression
439 using the LZMA algorithm, including support for the ``.xz`` and ``.lzma``
440 file formats.
441
442 (Contributed by Nadeem Vawda and Per Øyvind Karlsen in :issue:`6715`)
116 443
117 444
118 math 445 math
119 ---- 446 ----
120 447
121 The :mod:`math` module has a new function: 448 The :mod:`math` module has a new function:
122 449
123 * :func:`~math.log2`: return the base-2 logarithm of *x* 450 * :func:`~math.log2`: return the base-2 logarithm of *x*
124 (Written by Mark Dickinson in :issue:`11888`). 451 (Written by Mark Dickinson in :issue:`11888`).
125 452
126 453
127 nntplib 454 nntplib
128 ------- 455 -------
129 456
130 The :class:`nntplib.NNTP` class now supports the context manager protocol to 457 The :class:`nntplib.NNTP` class now supports the context manager protocol to
131 unconditionally consume :exc:`socket.error` exceptions and to close the NNTP 458 unconditionally consume :exc:`socket.error` exceptions and to close the NNTP
132 connection when done:: 459 connection when done::
133 460
134 >>> from nntplib import NNTP 461 >>> from nntplib import NNTP
135 >>> with nntplib.NNTP('news.gmane.org') as n: 462 >>> with NNTP('news.gmane.org') as n:
136 ... n.group('gmane.comp.python.committers') 463 ... n.group('gmane.comp.python.committers')
137 ... 464 ...
138 ('211 1454 1 1454 gmane.comp.python.committers', '1454', '1', '1454', 'gmane.c omp.python.committers') 465 ('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.py thon.committers')
139 >>> 466 >>>
140 467
141 (Contributed by Giampaolo Rodolà in :issue:`9795`) 468 (Contributed by Giampaolo Rodolà in :issue:`9795`)
142 469
143 470
144 os 471 os
145 -- 472 --
146 473
147 * The :mod:`os` module has a new :func:`~os.pipe2` function that makes it 474 * The :mod:`os` module has a new :func:`~os.pipe2` function that makes it
148 possible to create a pipe with :data:`~os.O_CLOEXEC` or 475 possible to create a pipe with :data:`~os.O_CLOEXEC` or
(...skipping 10 matching lines...) Expand all
159 486
160 (Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.) 487 (Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.)
161 488
162 * The :mod:`os` module has two new functions: :func:`~os.getpriority` and 489 * The :mod:`os` module has two new functions: :func:`~os.getpriority` and
163 :func:`~os.setpriority`. They can be used to get or set process 490 :func:`~os.setpriority`. They can be used to get or set process
164 niceness/priority in a fashion similar to :func:`os.nice` but extended to all 491 niceness/priority in a fashion similar to :func:`os.nice` but extended to all
165 processes instead of just the current one. 492 processes instead of just the current one.
166 493
167 (Patch submitted by Giampaolo Rodolà in :issue:`10784`.) 494 (Patch submitted by Giampaolo Rodolà in :issue:`10784`.)
168 495
496 * "at" functions (:issue:`4761`):
497
498 * :func:`~os.faccessat`
499 * :func:`~os.fchmodat`
500 * :func:`~os.fchownat`
501 * :func:`~os.fstatat`
502 * :func:`~os.futimesat`
503 * :func:`~os.futimesat`
504 * :func:`~os.linkat`
505 * :func:`~os.mkdirat`
506 * :func:`~os.mkfifoat`
507 * :func:`~os.mknodat`
508 * :func:`~os.openat`
509 * :func:`~os.readlinkat`
510 * :func:`~os.renameat`
511 * :func:`~os.symlinkat`
512 * :func:`~os.unlinkat`
513 * :func:`~os.utimensat`
514 * :func:`~os.utimensat`
515
516 * extended attributes (:issue:`12720`):
517
518 * :func:`~os.fgetxattr`
519 * :func:`~os.flistxattr`
520 * :func:`~os.fremovexattr`
521 * :func:`~os.fsetxattr`
522 * :func:`~os.getxattr`
523 * :func:`~os.lgetxattr`
524 * :func:`~os.listxattr`
525 * :func:`~os.llistxattr`
526 * :func:`~os.lremovexattr`
527 * :func:`~os.lsetxattr`
528 * :func:`~os.removexattr`
529 * :func:`~os.setxattr`
530
531 * Scheduler functions (:issue:`12655`):
532
533 * :func:`~os.sched_get_priority_max`
534 * :func:`~os.sched_get_priority_min`
535 * :func:`~os.sched_getaffinity`
536 * :func:`~os.sched_getparam`
537 * :func:`~os.sched_getscheduler`
538 * :func:`~os.sched_rr_get_interval`
539 * :func:`~os.sched_setaffinity`
540 * :func:`~os.sched_setparam`
541 * :func:`~os.sched_setscheduler`
542 * :func:`~os.sched_yield`
543
544 * Add some extra posix functions to the os module (:issue:`10812`):
545
546 * :func:`~os.fexecve`
547 * :func:`~os.futimens`
548 * :func:`~os.futimens`
549 * :func:`~os.futimes`
550 * :func:`~os.futimes`
551 * :func:`~os.lockf`
552 * :func:`~os.lutimes`
553 * :func:`~os.lutimes`
554 * :func:`~os.posix_fadvise`
555 * :func:`~os.posix_fallocate`
556 * :func:`~os.pread`
557 * :func:`~os.pwrite`
558 * :func:`~os.readv`
559 * :func:`~os.sync`
560 * :func:`~os.truncate`
561 * :func:`~os.waitid`
562 * :func:`~os.writev`
563
564 * Other new functions:
565
566 * :func:`~os.fdlistdir` (:issue:`10755`)
567 * :func:`~os.getgrouplist` (:issue:`9344`)
568
169 569
170 packaging 570 packaging
171 --------- 571 ---------
172 572
173 :mod:`distutils` has undergone additions and refactoring under a new name, 573 :mod:`distutils` has undergone additions and refactoring under a new name,
174 :mod:`packaging`, to allow developers to break backward compatibility. 574 :mod:`packaging`, to allow developers to break backward compatibility.
175 :mod:`distutils` is still provided in the standard library, but users are 575 :mod:`distutils` is still provided in the standard library, but users are
176 encouraged to transition to :mod:`packaging`. For older versions of Python, a 576 encouraged to transition to :mod:`packaging`. For older versions of Python, a
177 backport compatible with 2.4+ and 3.1+ will be made available on PyPI under the 577 backport compatible with 2.4+ and 3.1+ will be made available on PyPI under the
178 name :mod:`distutils2`. 578 name :mod:`distutils2`.
179 579
180 .. TODO add examples and howto to the packaging docs and link to them 580 .. TODO add examples and howto to the packaging docs and link to them
181 581
182 582
183 pydoc 583 pydoc
184 ----- 584 -----
185 585
186 The Tk GUI and the :func:`~pydoc.serve` function have been removed from the 586 The Tk GUI and the :func:`~pydoc.serve` function have been removed from the
187 :mod:`pydoc` module: ``pydoc -g`` and :func:`~pydoc.serve` have been deprecated 587 :mod:`pydoc` module: ``pydoc -g`` and :func:`~pydoc.serve` have been deprecated
188 in Python 3.2. 588 in Python 3.2.
189 589
190 590
191 sys 591 sys
192 --- 592 ---
193 593
194 * The :mod:`sys` module has a new :func:`~sys.thread_info` :term:`struct 594 * The :mod:`sys` module has a new :data:`~sys.thread_info` :term:`struct
195 sequence` holding informations about the thread implementation. 595 sequence` holding informations about the thread implementation.
196 596
197 (:issue:`11223`) 597 (:issue:`11223`)
198 598
199 599
200 signal 600 signal
201 ------ 601 ------
202 602
203 * The :mod:`signal` module has new functions: 603 * The :mod:`signal` module has new functions:
204 604
205 * :func:`~signal.pthread_sigmask`: fetch and/or change the signal mask of the 605 * :func:`~signal.pthread_sigmask`: fetch and/or change the signal mask of the
206 calling thread (Contributed by Jean-Paul Calderone in :issue:`8407`) ; 606 calling thread (Contributed by Jean-Paul Calderone in :issue:`8407`) ;
207 * :func:`~signal.pthread_kill`: send a signal to a thread ; 607 * :func:`~signal.pthread_kill`: send a signal to a thread ;
208 * :func:`~signal.sigpending`: examine pending functions ; 608 * :func:`~signal.sigpending`: examine pending functions ;
209 * :func:`~signal.sigwait`: wait a signal. 609 * :func:`~signal.sigwait`: wait a signal.
210 * :func:`~signal.sigwaitinfo`: wait for a signal, returning detailed 610 * :func:`~signal.sigwaitinfo`: wait for a signal, returning detailed
211 information about it. 611 information about it.
212 * :func:`~signal.sigtimedwait`: like :func:`~signal.sigwaitinfo` but with a 612 * :func:`~signal.sigtimedwait`: like :func:`~signal.sigwaitinfo` but with a
213 timeout. 613 timeout.
214 614
215 * The signal handler writes the signal number as a single byte instead of 615 * The signal handler writes the signal number as a single byte instead of
216 a nul byte into the wakeup file descriptor. So it is possible to wait more 616 a nul byte into the wakeup file descriptor. So it is possible to wait more
217 than one signal and know which signals were raised. 617 than one signal and know which signals were raised.
218 618
219 * :func:`signal.signal` and :func:`signal.siginterrupt` raise an OSError, 619 * :func:`signal.signal` and :func:`signal.siginterrupt` raise an OSError,
220 instead of a RuntimeError: OSError has an errno attribute. 620 instead of a RuntimeError: OSError has an errno attribute.
221 621
622 socket
623 ------
624
625 * The :class:`~socket.socket` class now exposes additional methods to process
626 ancillary data when supported by the underlying platform:
627
628 * :func:`~socket.socket.sendmsg`
629 * :func:`~socket.socket.recvmsg`
630 * :func:`~socket.socket.recvmsg_into`
631
632 (Contributed by David Watson in :issue:`6560`, based on an earlier patch by
633 Heiko Wundram)
634
635 * The :class:`~socket.socket` class now supports the PF_CAN protocol family
636 (http://en.wikipedia.org/wiki/Socketcan), on Linux
637 (http://lwn.net/Articles/253425).
638
639 (Contributed by Matthias Fuchs, updated by Tiago Gonçalves in :issue:`10141`)
640
641 * The :class:`~socket.socket` class now supports the PF_RDS protocol family
642 (http://en.wikipedia.org/wiki/Reliable_Datagram_Sockets and
643 http://oss.oracle.com/projects/rds/).
222 644
223 ssl 645 ssl
224 --- 646 ---
225 647
226 The :mod:`ssl` module has new functions: 648 * The :mod:`ssl` module has two new random generation functions:
227 649
228 * :func:`~ssl.RAND_bytes`: generate cryptographically strong 650 * :func:`~ssl.RAND_bytes`: generate cryptographically strong
229 pseudo-random bytes. 651 pseudo-random bytes.
230 * :func:`~ssl.RAND_pseudo_bytes`: generate pseudo-random bytes. 652 * :func:`~ssl.RAND_pseudo_bytes`: generate pseudo-random bytes.
231 653
232 654 (Contributed by Victor Stinner in :issue:`12049`)
233 ftplib 655
234 ------ 656 * The :mod:`ssl` module now exposes a finer-grained exception hierarchy
235 657 in order to make it easier to inspect the various kinds of errors.
236 The :class:`~ftplib.FTP_TLS` class now provides a new 658
237 :func:`~ftplib.FTP_TLS.ccc` function to revert control channel back to 659 (Contributed by Antoine Pitrou in :issue:`11183`)
238 plaintex. This can be useful to take advantage of firewalls that know how to 660
239 handle NAT with non-secure FTP without opening fixed ports. 661 * :meth:`~ssl.SSLContext.load_cert_chain` now accepts a *password* argument
240 662 to be used if the private key is encrypted.
241 (Contributed by Giampaolo Rodolà in :issue:`12139`) 663
664 (Contributed by Adam Simpkins in :issue:`12803`)
665
666 * Diffie-Hellman key exchange, both regular and Elliptic Curve-based, is
667 now supported through the :meth:`~ssl.SSLContext.load_dh_params` and
668 :meth:`~ssl.SSLContext.set_ecdh_curve` methods.
669
670 (Contributed by Antoine Pitrou in :issue:`13626` and :issue:`13627`)
671
672 * SSL sockets have a new :meth:`~ssl.SSLSocket.get_channel_binding` method
673 allowing the implementation of certain authentication mechanisms such as
674 SCRAM-SHA-1-PLUS.
675
676 (Contributed by Jacek Konieczny in :issue:`12551`)
677
678 * You can query the SSL compression algorithm used by an SSL socket, thanks
679 to its new :meth:`~ssl.SSLSocket.compression` method.
680
681 (Contributed by Antoine Pitrou in :issue:`13634`)
242 682
243 683
244 shutil 684 shutil
245 ------ 685 ------
246 686
247 The :mod:`shutil` module has a new :func:`~shutil.disk_usage` function providing total, 687 * The :mod:`shutil` module has these new fuctions:
248 used and free disk space statistics. 688
249 689 * :func:`~shutil.disk_usage`: provides total, used and free disk space
250 (Contributed by Giampaolo Rodolà in :issue:`12442`) 690 statistics. (Contributed by Giampaolo Rodolà in :issue:`12442`)
251 691 * :func:`~shutil.chown`: allows one to change user and/or group of the given
692 path also specifying the user/group names and not only their numeric
693 ids. (Contributed by Sandro Tosi in :issue:`12191`)
694
695 smtplib
696 -------
697
698 The :class:`~smtplib.SMTP_SSL` constructor and the :meth:`~smtplib.SMTP.starttls `
699 method now accept an SSLContext parameter to control parameters of the secure
700 channel.
701
702 (Contributed by Kasun Herath in :issue:`8809`)
703
704 urllib
705 ------
706
707 The :class:`~urllib.request.Request` class, now accepts a *method* argument
708 used by :meth:`~urllib.request.Request.get_method` to determine what HTTP method
709 should be used. For example, this will send a ``'HEAD'`` request::
710
711 >>> urlopen(Request('http://www.python.org', method='HEAD'))
712
713 (:issue:`1673007`)
714
715 sched
716 -----
717
718 * :meth:`~sched.scheduler.run` now accepts a *blocking* parameter which when
719 set to False makes the method execute the scheduled events due to expire
720 soonest (if any) and then return immediately.
721 This is useful in case you want to use the :class:`~sched.scheduler` in
722 non-blocking applications. (Contributed by Giampaolo Rodolà in :issue:`13449` )
723
724 * :class:`~sched.scheduler` class can now be safely used in multi-threaded
725 environments. (Contributed by Josiah Carlson and Giampaolo Rodolà in
726 :issue:`8684`)
727
728 * *timefunc* and *delayfunct* parameters of :class:`~sched.scheduler` class
729 constructor are now optional and defaults to :func:`time.time` and
730 :func:`time.sleep` respectively. (Contributed by Chris Clark in
731 :issue:`13245`)
732
733 * :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs`
734 *argument* parameter is now optional. (Contributed by Chris Clark in
735 :issue:`13245`)
736
737 * :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs`
738 now accept a *kwargs* parameter. (Contributed by Chris Clark in
739 :issue:`13245`)
252 740
253 Optimizations 741 Optimizations
254 ============= 742 =============
255 743
256 Major performance enhancements have been added: 744 Major performance enhancements have been added:
257 745
258 * Stub 746 * Thanks to the :pep:`393`, some operations on Unicode strings has been optimize d:
747
748 * the memory footprint is divided by 2 to 4 depending on the text
749 * encode an ASCII string to UTF-8 doesn't need to encode characters anymore,
750 the UTF-8 representation is shared with the ASCII representation
751 * the UTF-8 encoder has been optimized
752 * repeating a single ASCII letter and getting a substring of a ASCII strings
753 is 4 times faster
259 754
260 755
261 Build and C API Changes 756 Build and C API Changes
262 ======================= 757 =======================
263 758
264 Changes to Python's build process and to the C API include: 759 Changes to Python's build process and to the C API include:
265 760
266 * Stub 761 * The :pep:`393` added new Unicode types, macros and functions:
267 762
763 * High-level API:
764
765 * :c:func:`PyUnicode_CopyCharacters`
766 * :c:func:`PyUnicode_FindChar`
767 * :c:func:`PyUnicode_GetLength`, :c:macro:`PyUnicode_GET_LENGTH`
768 * :c:func:`PyUnicode_New`
769 * :c:func:`PyUnicode_Substring`
770 * :c:func:`PyUnicode_ReadChar`, :c:func:`PyUnicode_WriteChar`
771
772 * Low-level API:
773
774 * :c:type:`Py_UCS1`, :c:type:`Py_UCS2`, :c:type:`Py_UCS4` types
775 * :c:type:`PyASCIIObject` and :c:type:`PyCompactUnicodeObject` structures
776 * :c:macro:`PyUnicode_READY`
777 * :c:func:`PyUnicode_FromKindAndData`
778 * :c:func:`PyUnicode_AsUCS4`, :c:func:`PyUnicode_AsUCS4Copy`
779 * :c:macro:`PyUnicode_DATA`, :c:macro:`PyUnicode_1BYTE_DATA`,
780 :c:macro:`PyUnicode_2BYTE_DATA`, :c:macro:`PyUnicode_4BYTE_DATA`
781 * :c:macro:`PyUnicode_KIND` with :c:type:`PyUnicode_Kind` enum:
782 :c:data:`PyUnicode_WCHAR_KIND`, :c:data:`PyUnicode_1BYTE_KIND`,
783 :c:data:`PyUnicode_2BYTE_KIND`, :c:data:`PyUnicode_4BYTE_KIND`
784 * :c:macro:`PyUnicode_READ`, :c:macro:`PyUnicode_READ_CHAR`, :c:macro:`PyUni code_WRITE`
785 * :c:macro:`PyUnicode_MAX_CHAR_VALUE`
786
787
788
789 Deprecated
790 ==========
268 791
269 Unsupported Operating Systems 792 Unsupported Operating Systems
270 ============================= 793 -----------------------------
271 794
272 OS/2 and VMS are no longer supported due to the lack of a maintainer. 795 OS/2 and VMS are no longer supported due to the lack of a maintainer.
273 796
274 Windows 2000 and Windows platforms which set ``COMSPEC`` to ``command.com`` 797 Windows 2000 and Windows platforms which set ``COMSPEC`` to ``command.com``
275 are no longer supported due to maintenance burden. 798 are no longer supported due to maintenance burden.
276 799
277 800
801 Deprecated Python modules, functions and methods
802 ------------------------------------------------
803
804 * The :mod:`packaging` module replaces the :mod:`distutils` module
805 * The ``unicode_internal`` codec has been deprecated because of the
806 :pep:`393`, use UTF-8, UTF-16 (``utf-16-le`` or ``utf-16-le``), or UTF-32
807 (``utf-32-le`` or ``utf-32-le``)
808 * :meth:`ftplib.FTP.nlst` and :meth:`ftplib.FTP.dir`: use
809 :meth:`ftplib.FTP.mlsd`
810 * :func:`platform.popen`: use the :mod:`subprocess` module. Check especially
811 the :ref:`subprocess-replacements` section.
812 * :issue:`13374`: The Windows bytes API has been deprecated in the :mod:`os`
813 module. Use Unicode filenames, instead of bytes filenames, to not depend on
814 the ANSI code page anymore and to support any filename.
815
816
817 Deprecated functions and types of the C API
818 -------------------------------------------
819
820 The :c:type:`Py_UNICODE` has been deprecated by the :pep:`393` and will be
821 removed in Python 4. All functions using this type are deprecated:
822
823 Unicode functions and methods using :c:type:`Py_UNICODE` and
824 :c:type:`Py_UNICODE*` types:
825
826 * :c:macro:`PyUnicode_FromUnicode`: use :c:func:`PyUnicode_FromWideChar` or
827 :c:func:`PyUnicode_FromKindAndData`
828 * :c:macro:`PyUnicode_AS_UNICODE`, :c:func:`PyUnicode_AsUnicode`,
829 :c:func:`PyUnicode_AsUnicodeAndSize`: use :c:func:`PyUnicode_AsWideCharString `
830 * :c:macro:`PyUnicode_AS_DATA`: use :c:macro:`PyUnicode_DATA` with
831 :c:macro:`PyUnicode_READ` and :c:macro:`PyUnicode_WRITE`
832 * :c:macro:`PyUnicode_GET_SIZE`, :c:func:`PyUnicode_GetSize`: use
833 :c:macro:`PyUnicode_GET_LENGTH` or :c:func:`PyUnicode_GetLength`
834 * :c:macro:`PyUnicode_GET_DATA_SIZE`: use
835 ``PyUnicode_GET_LENGTH(str) * PyUnicode_KIND(str)`` (only work on ready
836 strings)
837 * :c:func:`PyUnicode_AsUnicodeCopy`: use :c:func:`PyUnicode_AsUCS4Copy` or
838 :c:func:`PyUnicode_AsWideCharString`
839 * :c:func:`PyUnicode_GetMax`
840
841
842 Functions and macros manipulating Py_UNICODE* strings:
843
844 * :c:macro:`Py_UNICODE_strlen`: use :c:func:`PyUnicode_GetLength` or
845 :c:macro:`PyUnicode_GET_LENGTH`
846 * :c:macro:`Py_UNICODE_strcat`: use :c:func:`PyUnicode_CopyCharacters` or
847 :c:func:`PyUnicode_FromFormat`
848 * :c:macro:`Py_UNICODE_strcpy`, :c:macro:`Py_UNICODE_strncpy`,
849 :c:macro:`Py_UNICODE_COPY`: use :c:func:`PyUnicode_CopyCharacters` or
850 :c:func:`PyUnicode_Substring`
851 * :c:macro:`Py_UNICODE_strcmp`: use :c:func:`PyUnicode_Compare`
852 * :c:macro:`Py_UNICODE_strncmp`: use :c:func:`PyUnicode_Tailmatch`
853 * :c:macro:`Py_UNICODE_strchr`, :c:macro:`Py_UNICODE_strrchr`: use
854 :c:func:`PyUnicode_FindChar`
855 * :c:macro:`Py_UNICODE_FILL`: use :c:func:`PyUnicode_Fill`
856 * :c:macro:`Py_UNICODE_MATCH`
857
858 Encoders:
859
860 * :c:func:`PyUnicode_Encode`: use :c:func:`PyUnicode_AsEncodedObject`
861 * :c:func:`PyUnicode_EncodeUTF7`
862 * :c:func:`PyUnicode_EncodeUTF8`: use :c:func:`PyUnicode_AsUTF8` or
863 :c:func:`PyUnicode_AsUTF8String`
864 * :c:func:`PyUnicode_EncodeUTF32`
865 * :c:func:`PyUnicode_EncodeUTF16`
866 * :c:func:`PyUnicode_EncodeUnicodeEscape:` use
867 :c:func:`PyUnicode_AsUnicodeEscapeString`
868 * :c:func:`PyUnicode_EncodeRawUnicodeEscape:` use
869 :c:func:`PyUnicode_AsRawUnicodeEscapeString`
870 * :c:func:`PyUnicode_EncodeLatin1`: use :c:func:`PyUnicode_AsLatin1String`
871 * :c:func:`PyUnicode_EncodeASCII`: use :c:func:`PyUnicode_AsASCIIString`
872 * :c:func:`PyUnicode_EncodeCharmap`
873 * :c:func:`PyUnicode_TranslateCharmap`
874 * :c:func:`PyUnicode_EncodeMBCS`: use :c:func:`PyUnicode_AsMBCSString` or
875 :c:func:`PyUnicode_EncodeCodePage` (with ``CP_ACP`` code_page)
876 * :c:func:`PyUnicode_EncodeDecimal`,
877 :c:func:`PyUnicode_TransformDecimalToASCII`
878
879
278 Porting to Python 3.3 880 Porting to Python 3.3
279 ===================== 881 =====================
280 882
281 This section lists previously described changes and other bugfixes 883 This section lists previously described changes and other bugfixes
282 that may require changes to your code: 884 that may require changes to your code.
283 885
284 * Stub 886 Porting Python code
285 887 -------------------
888
889 * :issue:`12326`: On Linux, sys.platform doesn't contain the major version
890 anymore. It is now always 'linux', instead of 'linux2' or 'linux3' depending
891 on the Linux version used to build Python. Replace sys.platform == 'linux2'
892 with sys.platform.startswith('linux'), or directly sys.platform == 'linux' if
893 you don't need to support older Python versions.
894
895 Porting C code
896 --------------
897
898 * Due to :ref:`PEP 393 <pep-393>`, the :c:type:`Py_UNICODE` type and all
899 functions using this type are deprecated (but will stay available for
900 at least five years). If you were using low-level Unicode APIs to
901 construct and access unicode objects and you want to benefit of the
902 memory footprint reduction provided by the PEP 393, you have to convert
903 your code to the new :doc:`Unicode API <../c-api/unicode>`.
904
905 However, if you only have been using high-level functions such as
906 :c:func:`PyUnicode_Concat()`, :c:func:`PyUnicode_Join` or
907 :c:func:`PyUnicode_FromFormat()`, your code will automatically take
908 advantage of the new unicode representations.
909
910 Other issues
911 ------------
286 912
287 .. Issue #11591: When :program:`python` was started with :option:`-S`, 913 .. Issue #11591: When :program:`python` was started with :option:`-S`,
288 ``import site`` will not add site-specific paths to the module search 914 ``import site`` will not add site-specific paths to the module search
289 paths. In previous versions, it did. See changeset for doc changes in 915 paths. In previous versions, it did. See changeset for doc changes in
290 various files. Contributed by Carl Meyer with editions by Éric Araujo. 916 various files. Contributed by Carl Meyer with editions by Éric Araujo.
291 917
292 .. Issue #10998: -Q command-line flags are related artifacts have been 918 .. Issue #10998: the -Q command-line flag and related artifacts have been
293 removed. Code checking sys.flags.division_warning will need updating. 919 removed. Code checking sys.flags.division_warning will need updating.
294 Contributed by Éric Araujo. 920 Contributed by Éric Araujo.
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