Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 1 | **************************** |
| 2 | What's New In Python 3.6 |
| 3 | **************************** |
| 4 | |
| 5 | :Release: |release| |
| 6 | :Date: |today| |
| 7 | |
| 8 | .. Rules for maintenance: |
| 9 | |
| 10 | * Anyone can add text to this document. Do not spend very much time |
| 11 | on the wording of your changes, because your text will probably |
| 12 | get rewritten to some degree. |
| 13 | |
| 14 | * The maintainer will go through Misc/NEWS periodically and add |
| 15 | changes; it's therefore more important to add your changes to |
| 16 | Misc/NEWS than to this file. |
| 17 | |
| 18 | * This is not a complete list of every single change; completeness |
| 19 | is the purpose of Misc/NEWS. Some changes I consider too small |
| 20 | or esoteric to include. If such a change is added to the text, |
| 21 | I'll just remove it. (This is another reason you shouldn't spend |
| 22 | too much time on writing your addition.) |
| 23 | |
| 24 | * If you want to draw your new text to the attention of the |
| 25 | maintainer, add 'XXX' to the beginning of the paragraph or |
| 26 | section. |
| 27 | |
| 28 | * It's OK to just add a fragmentary note about a change. For |
| 29 | example: "XXX Describe the transmogrify() function added to the |
| 30 | socket module." The maintainer will research the change and |
| 31 | write the necessary text. |
| 32 | |
| 33 | * You can comment out your additions if you like, but it's not |
| 34 | necessary (especially when a final release is some months away). |
| 35 | |
| 36 | * Credit the author of a patch or bugfix. Just the name is |
| 37 | sufficient; the e-mail address isn't necessary. |
| 38 | |
| 39 | * It's helpful to add the bug/patch number as a comment: |
| 40 | |
| 41 | XXX Describe the transmogrify() function added to the socket |
| 42 | module. |
| 43 | (Contributed by P.Y. Developer in :issue:`12345`.) |
| 44 | |
| 45 | This saves the maintainer the effort of going through the Mercurial log |
| 46 | when researching a change. |
| 47 | |
| 48 | This article explains the new features in Python 3.6, compared to 3.5. |
| 49 | |
| 50 | For full details, see the :source:`Misc/NEWS` file. |
| 51 | |
| 52 | .. note:: |
| 53 | |
| 54 | Prerelease users should be aware that this document is currently in draft |
| 55 | form. It will be updated substantially as Python 3.6 moves towards release, |
| 56 | so it's worth checking back even after reading earlier versions. |
| 57 | |
| 58 | |
| 59 | Summary -- Release highlights |
| 60 | ============================= |
| 61 | |
| 62 | .. This section singles out the most important changes in Python 3.6. |
| 63 | Brevity is key. |
| 64 | |
Martin Panter | bc1ee46 | 2016-02-13 00:41:37 +0000 | [diff] [blame] | 65 | * PEP 498: :ref:`Formatted string literals <whatsnew-fstrings>` |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 66 | |
| 67 | .. PEP-sized items next. |
| 68 | |
| 69 | .. _pep-4XX: |
| 70 | |
| 71 | .. PEP 4XX: Virtual Environments |
| 72 | .. ============================= |
| 73 | |
| 74 | |
| 75 | .. (Implemented by Foo Bar.) |
| 76 | |
| 77 | .. .. seealso:: |
| 78 | |
| 79 | :pep:`4XX` - Python Virtual Environments |
| 80 | PEP written by Carl Meyer |
| 81 | |
| 82 | |
Victor Stinner | 34be807 | 2016-03-14 12:04:26 +0100 | [diff] [blame] | 83 | New Features |
| 84 | ============ |
| 85 | |
Martin Panter | bc1ee46 | 2016-02-13 00:41:37 +0000 | [diff] [blame] | 86 | .. _whatsnew-fstrings: |
| 87 | |
| 88 | PEP 498: Formatted string literals |
| 89 | ---------------------------------- |
| 90 | |
| 91 | Formatted string literals are a new kind of string literal, prefixed |
| 92 | with ``'f'``. They are similar to the format strings accepted by |
| 93 | :meth:`str.format`. They contain replacement fields surrounded by |
| 94 | curly braces. The replacement fields are expressions, which are |
| 95 | evaluated at run time, and then formatted using the :func:`format` protocol. |
| 96 | |
| 97 | >>> name = "Fred" |
| 98 | >>> f"He said his name is {name}." |
| 99 | 'He said his name is Fred.' |
| 100 | |
| 101 | See :pep:`498` and the main documentation at :ref:`f-strings`. |
| 102 | |
| 103 | |
Victor Stinner | 34be807 | 2016-03-14 12:04:26 +0100 | [diff] [blame] | 104 | PYTHONMALLOC environment variable |
| 105 | --------------------------------- |
| 106 | |
| 107 | The new :envvar:`PYTHONMALLOC` environment variable allows to set the Python |
| 108 | memory allocators and/or install debug hooks. |
| 109 | |
| 110 | It is now possible to install debug hooks on Python memory allocators on Python |
| 111 | compiled in release mode using ``PYTHONMALLOC=debug``. Effects of debug hooks: |
| 112 | |
| 113 | * Newly allocated memory is filled with the byte ``0xCB`` |
| 114 | * Freed memory is filled with the byte ``0xDB`` |
| 115 | * Detect violations of Python memory allocator API. For example, |
| 116 | :c:func:`PyObject_Free` called on a memory block allocated by |
| 117 | :c:func:`PyMem_Malloc`. |
| 118 | * Detect write before the start of the buffer (buffer underflow) |
| 119 | * Detect write after the end of the buffer (buffer overflow) |
Victor Stinner | c4aec36 | 2016-03-14 22:26:53 +0100 | [diff] [blame] | 120 | * Check that the :term:`GIL <global interpreter lock>` is held when allocator |
Victor Stinner | c2fc568 | 2016-03-18 11:04:31 +0100 | [diff] [blame] | 121 | functions of :c:data:`PYMEM_DOMAIN_OBJ` (ex: :c:func:`PyObject_Malloc`) and |
| 122 | :c:data:`PYMEM_DOMAIN_MEM` (ex: :c:func:`PyMem_Malloc`) domains are called. |
| 123 | |
Victor Stinner | 9b46a57 | 2016-03-18 15:10:43 +0100 | [diff] [blame] | 124 | Checking if the GIL is held is also a new feature of Python 3.6. |
Victor Stinner | 34be807 | 2016-03-14 12:04:26 +0100 | [diff] [blame] | 125 | |
| 126 | See the :c:func:`PyMem_SetupDebugHooks` function for debug hooks on Python |
| 127 | memory allocators. |
| 128 | |
| 129 | It is now also possible to force the usage of the :c:func:`malloc` allocator of |
| 130 | the C library for all Python memory allocations using ``PYTHONMALLOC=malloc``. |
| 131 | It helps to use external memory debuggers like Valgrind on a Python compiled in |
| 132 | release mode. |
| 133 | |
Victor Stinner | 0611c26 | 2016-03-15 22:22:13 +0100 | [diff] [blame] | 134 | On error, the debug hooks on Python memory allocators now use the |
| 135 | :mod:`tracemalloc` module to get the traceback where a memory block was |
| 136 | allocated. |
| 137 | |
| 138 | Example of fatal error on buffer overflow using |
| 139 | ``python3.6 -X tracemalloc=5`` (store 5 frames in traces):: |
| 140 | |
| 141 | Debug memory block at address p=0x7fbcd41666f8: API 'o' |
| 142 | 4 bytes originally requested |
| 143 | The 7 pad bytes at p-7 are FORBIDDENBYTE, as expected. |
| 144 | The 8 pad bytes at tail=0x7fbcd41666fc are not all FORBIDDENBYTE (0xfb): |
| 145 | at tail+0: 0x02 *** OUCH |
| 146 | at tail+1: 0xfb |
| 147 | at tail+2: 0xfb |
| 148 | at tail+3: 0xfb |
| 149 | at tail+4: 0xfb |
| 150 | at tail+5: 0xfb |
| 151 | at tail+6: 0xfb |
| 152 | at tail+7: 0xfb |
| 153 | The block was made by call #1233329 to debug malloc/realloc. |
| 154 | Data at p: 1a 2b 30 00 |
| 155 | |
| 156 | Memory block allocated at (most recent call first): |
| 157 | File "test/test_bytes.py", line 323 |
| 158 | File "unittest/case.py", line 600 |
| 159 | File "unittest/case.py", line 648 |
| 160 | File "unittest/suite.py", line 122 |
| 161 | File "unittest/suite.py", line 84 |
| 162 | |
| 163 | Fatal Python error: bad trailing pad byte |
| 164 | |
| 165 | Current thread 0x00007fbcdbd32700 (most recent call first): |
| 166 | File "test/test_bytes.py", line 323 in test_hex |
| 167 | File "unittest/case.py", line 600 in run |
| 168 | File "unittest/case.py", line 648 in __call__ |
| 169 | File "unittest/suite.py", line 122 in run |
| 170 | File "unittest/suite.py", line 84 in __call__ |
| 171 | File "unittest/suite.py", line 122 in run |
| 172 | File "unittest/suite.py", line 84 in __call__ |
| 173 | ... |
| 174 | |
| 175 | (Contributed by Victor Stinner in :issue:`26516` and :issue:`26564`.) |
Victor Stinner | 34be807 | 2016-03-14 12:04:26 +0100 | [diff] [blame] | 176 | |
| 177 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 178 | Other Language Changes |
| 179 | ====================== |
| 180 | |
| 181 | * None yet. |
| 182 | |
| 183 | |
| 184 | New Modules |
| 185 | =========== |
| 186 | |
| 187 | * None yet. |
| 188 | |
| 189 | |
| 190 | Improved Modules |
| 191 | ================ |
| 192 | |
Brett Cannon | 9e080e0 | 2016-04-08 12:15:27 -0700 | [diff] [blame] | 193 | contextlib |
| 194 | ---------- |
| 195 | |
| 196 | The :class:`contextlib.AbstractContextManager` class has been added to |
| 197 | provide an abstract base class for context managers. It provides a |
| 198 | sensible default implementation for `__enter__()` which returns |
Martin Panter | 3872d62 | 2016-04-10 02:41:25 +0000 | [diff] [blame] | 199 | ``self`` and leaves `__exit__()` an abstract method. A matching |
Brett Cannon | 9e080e0 | 2016-04-08 12:15:27 -0700 | [diff] [blame] | 200 | class has been added to the :mod:`typing` module as |
| 201 | :class:`typing.ContextManager`. |
| 202 | (Contributed by Brett Cannon in :issue:`25609`.) |
| 203 | |
| 204 | |
Berker Peksag | b6c9572 | 2015-10-08 13:58:49 +0300 | [diff] [blame] | 205 | datetime |
| 206 | -------- |
| 207 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 208 | The :meth:`datetime.strftime() <datetime.datetime.strftime>` and |
| 209 | :meth:`date.strftime() <datetime.date.strftime>` methods now support ISO 8601 date |
Berker Peksag | b6c9572 | 2015-10-08 13:58:49 +0300 | [diff] [blame] | 210 | directives ``%G``, ``%u`` and ``%V``. |
| 211 | (Contributed by Ashley Anderson in :issue:`12006`.) |
| 212 | |
| 213 | |
Victor Stinner | 404cdc5 | 2016-03-23 10:39:17 +0100 | [diff] [blame] | 214 | faulthandler |
| 215 | ------------ |
| 216 | |
Serhiy Storchaka | b6a9c97 | 2016-04-17 09:39:28 +0300 | [diff] [blame^] | 217 | On Windows, the :mod:`faulthandler` module now installs a handler for Windows |
Victor Stinner | 404cdc5 | 2016-03-23 10:39:17 +0100 | [diff] [blame] | 218 | exceptions: see :func:`faulthandler.enable`. (Contributed by Victor Stinner in |
| 219 | :issue:`23848`.) |
| 220 | |
| 221 | |
Serhiy Storchaka | ffe96ae | 2016-02-11 13:21:30 +0200 | [diff] [blame] | 222 | os |
| 223 | -- |
| 224 | |
| 225 | A new :meth:`~os.scandir.close` method allows explicitly closing a |
| 226 | :func:`~os.scandir` iterator. The :func:`~os.scandir` iterator now |
| 227 | supports the :term:`context manager` protocol. If a :func:`scandir` |
| 228 | iterator is neither exhausted nor explicitly closed a :exc:`ResourceWarning` |
| 229 | will be emitted in its destructor. |
| 230 | (Contributed by Serhiy Storchaka in :issue:`25994`.) |
| 231 | |
| 232 | |
Serhiy Storchaka | 0d554d7 | 2015-10-10 22:42:18 +0300 | [diff] [blame] | 233 | pickle |
| 234 | ------ |
| 235 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 236 | Objects that need calling ``__new__`` with keyword arguments can now be pickled |
Serhiy Storchaka | 0d554d7 | 2015-10-10 22:42:18 +0300 | [diff] [blame] | 237 | using :ref:`pickle protocols <pickle-protocols>` older than protocol version 4. |
| 238 | Protocol version 4 already supports this case. (Contributed by Serhiy |
| 239 | Storchaka in :issue:`24164`.) |
| 240 | |
| 241 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 242 | rlcompleter |
| 243 | ----------- |
Serhiy Storchaka | ab82422 | 2015-09-27 13:43:50 +0300 | [diff] [blame] | 244 | |
| 245 | Private and special attribute names now are omitted unless the prefix starts |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 246 | with underscores. A space or a colon is added after some completed keywords. |
Serhiy Storchaka | ab82422 | 2015-09-27 13:43:50 +0300 | [diff] [blame] | 247 | (Contributed by Serhiy Storchaka in :issue:`25011` and :issue:`25209`.) |
| 248 | |
Martin Panter | 6fe3926 | 2015-11-13 23:54:02 +0000 | [diff] [blame] | 249 | Names of most attributes listed by :func:`dir` are now completed. |
| 250 | Previously, names of properties and slots which were not yet created on |
| 251 | an instance were excluded. (Contributed by Martin Panter in :issue:`25590`.) |
| 252 | |
Serhiy Storchaka | ab82422 | 2015-09-27 13:43:50 +0300 | [diff] [blame] | 253 | |
Brett Cannon | 5f0507d | 2016-04-08 15:04:28 -0700 | [diff] [blame] | 254 | site |
| 255 | ---- |
| 256 | |
| 257 | When specifying paths to add to :attr:`sys.path` in a `.pth` file, |
| 258 | you may now specify file paths on top of directories (e.g. zip files). |
| 259 | (Contributed by Wolfgang Langner in :issue:`26587`). |
| 260 | |
| 261 | |
Martin Panter | 0cab9c1 | 2016-04-13 00:36:52 +0000 | [diff] [blame] | 262 | socketserver |
| 263 | ------------ |
| 264 | |
| 265 | Servers based on the :mod:`socketserver` module, including those |
| 266 | defined in :mod:`http.server`, :mod:`xmlrpc.server` and |
| 267 | :mod:`wsgiref.simple_server`, now support the :term:`context manager` |
| 268 | protocol. |
| 269 | (Contributed by Aviv Palivoda in :issue:`26404`.) |
| 270 | |
| 271 | |
R David Murray | 4f09806 | 2015-11-28 12:24:52 -0500 | [diff] [blame] | 272 | telnetlib |
| 273 | --------- |
| 274 | |
| 275 | :class:`~telnetlib.Telnet` is now a context manager (contributed by |
| 276 | Stéphane Wirtel in :issue:`25485`). |
| 277 | |
| 278 | |
Brett Cannon | 9e080e0 | 2016-04-08 12:15:27 -0700 | [diff] [blame] | 279 | typing |
| 280 | ------ |
| 281 | |
| 282 | The :class:`typing.ContextManager` class has been added for |
| 283 | representing :class:`contextlib.AbstractContextManager`. |
| 284 | (Contributed by Brett Cannon in :issue:`25609`.) |
| 285 | |
| 286 | |
Victor Stinner | 2c2a4e6 | 2016-03-11 22:17:48 +0100 | [diff] [blame] | 287 | unittest.mock |
| 288 | ------------- |
| 289 | |
| 290 | The :class:`~unittest.mock.Mock` class has the following improvements: |
| 291 | |
| 292 | * Two new methods, :meth:`Mock.assert_called() |
| 293 | <unittest.mock.Mock.assert_called>` and :meth:`Mock.assert_called_once() |
| 294 | <unittest.mock.Mock.assert_called_once>` to check if the mock object |
| 295 | was called. |
| 296 | (Contributed by Amit Saha in :issue:`26323`.) |
| 297 | |
| 298 | |
Berker Peksag | 960e848 | 2015-10-08 12:27:06 +0300 | [diff] [blame] | 299 | urllib.robotparser |
| 300 | ------------------ |
| 301 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 302 | :class:`~urllib.robotparser.RobotFileParser` now supports the ``Crawl-delay`` and |
Berker Peksag | 960e848 | 2015-10-08 12:27:06 +0300 | [diff] [blame] | 303 | ``Request-rate`` extensions. |
| 304 | (Contributed by Nikolay Bogoychev in :issue:`16099`.) |
| 305 | |
| 306 | |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 307 | warnings |
| 308 | -------- |
| 309 | |
| 310 | A new optional *source* parameter has been added to the |
| 311 | :func:`warnings.warn_explicit` function: the destroyed object which emitted a |
| 312 | :exc:`ResourceWarning`. A *source* attribute has also been added to |
| 313 | :class:`warnings.WarningMessage` (contributed by Victor Stinner in |
| 314 | :issue:`26568` and :issue:`26567`). |
| 315 | |
| 316 | When a :exc:`ResourceWarning` warning is logged, the :mod:`tracemalloc` is now |
| 317 | used to try to retrieve the traceback where the detroyed object was allocated. |
| 318 | |
| 319 | Example with the script ``example.py``:: |
| 320 | |
Victor Stinner | ee803a8 | 2016-03-19 10:33:25 +0100 | [diff] [blame] | 321 | import warnings |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 322 | |
Victor Stinner | ee803a8 | 2016-03-19 10:33:25 +0100 | [diff] [blame] | 323 | def func(): |
| 324 | return open(__file__) |
| 325 | |
| 326 | f = func() |
| 327 | f = None |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 328 | |
| 329 | Output of the command ``python3.6 -Wd -X tracemalloc=5 example.py``:: |
| 330 | |
Victor Stinner | ee803a8 | 2016-03-19 10:33:25 +0100 | [diff] [blame] | 331 | example.py:7: ResourceWarning: unclosed file <_io.TextIOWrapper name='example.py' mode='r' encoding='UTF-8'> |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 332 | f = None |
| 333 | Object allocated at (most recent call first): |
Victor Stinner | ee803a8 | 2016-03-19 10:33:25 +0100 | [diff] [blame] | 334 | File "example.py", lineno 4 |
| 335 | return open(__file__) |
| 336 | File "example.py", lineno 6 |
| 337 | f = func() |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 338 | |
| 339 | The "Object allocated at" traceback is new and only displayed if |
Victor Stinner | ee803a8 | 2016-03-19 10:33:25 +0100 | [diff] [blame] | 340 | :mod:`tracemalloc` is tracing Python memory allocations and if the |
| 341 | :mod:`warnings` was already imported. |
Victor Stinner | 914cde8 | 2016-03-19 01:03:51 +0100 | [diff] [blame] | 342 | |
| 343 | |
Serhiy Storchaka | 503f908 | 2016-02-08 00:02:25 +0200 | [diff] [blame] | 344 | zipfile |
| 345 | ------- |
| 346 | |
| 347 | A new :meth:`ZipInfo.from_file() <zipfile.ZipInfo.from_file>` class method |
Martin Panter | 288ed03 | 2016-02-10 05:45:55 +0000 | [diff] [blame] | 348 | allows making a :class:`~zipfile.ZipInfo` instance from a filesystem file. |
Serhiy Storchaka | 503f908 | 2016-02-08 00:02:25 +0200 | [diff] [blame] | 349 | A new :meth:`ZipInfo.is_dir() <zipfile.ZipInfo.is_dir>` method can be used |
| 350 | to check if the :class:`~zipfile.ZipInfo` instance represents a directory. |
| 351 | (Contributed by Thomas Kluyver in :issue:`26039`.) |
| 352 | |
| 353 | |
Martin Panter | 1fe0d13 | 2016-02-10 10:06:36 +0000 | [diff] [blame] | 354 | zlib |
| 355 | ---- |
| 356 | |
| 357 | The :func:`~zlib.compress` function now accepts keyword arguments. |
| 358 | (Contributed by Aviv Palivoda in :issue:`26243`.) |
| 359 | |
| 360 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 361 | Optimizations |
| 362 | ============= |
| 363 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 364 | * The ASCII decoder is now up to 60 times as fast for error handlers |
Victor Stinner | ebcf9ed | 2015-10-14 10:10:00 +0200 | [diff] [blame] | 365 | ``surrogateescape``, ``ignore`` and ``replace`` (Contributed |
| 366 | by Victor Stinner in :issue:`24870`). |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 367 | |
Terry Jan Reedy | 6dc9ce1 | 2015-10-20 01:07:53 -0400 | [diff] [blame] | 368 | * The ASCII and the Latin1 encoders are now up to 3 times as fast for the |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 369 | error handler ``surrogateescape`` (Contributed by Victor Stinner in :issue:`25227`). |
Victor Stinner | c3713e9 | 2015-09-29 12:32:13 +0200 | [diff] [blame] | 370 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 371 | * The UTF-8 encoder is now up to 75 times as fast for error handlers |
Victor Stinner | ebcf9ed | 2015-10-14 10:10:00 +0200 | [diff] [blame] | 372 | ``ignore``, ``replace``, ``surrogateescape``, ``surrogatepass`` (Contributed |
| 373 | by Victor Stinner in :issue:`25267`). |
Victor Stinner | 01ada39 | 2015-10-01 21:54:51 +0200 | [diff] [blame] | 374 | |
Martin Panter | fad4b60 | 2015-11-14 01:29:17 +0000 | [diff] [blame] | 375 | * The UTF-8 decoder is now up to 15 times as fast for error handlers |
Victor Stinner | ebcf9ed | 2015-10-14 10:10:00 +0200 | [diff] [blame] | 376 | ``ignore``, ``replace`` and ``surrogateescape`` (Contributed |
| 377 | by Victor Stinner in :issue:`25301`). |
| 378 | |
| 379 | * ``bytes % args`` is now up to 2 times faster. (Contributed by Victor Stinner |
| 380 | in :issue:`25349`). |
| 381 | |
| 382 | * ``bytearray % args`` is now between 2.5 and 5 times faster. (Contributed by |
| 383 | Victor Stinner in :issue:`25399`). |
Victor Stinner | 1d65d91 | 2015-10-05 13:43:50 +0200 | [diff] [blame] | 384 | |
Victor Stinner | 2bf8993 | 2015-10-14 11:25:33 +0200 | [diff] [blame] | 385 | * Optimize :meth:`bytes.fromhex` and :meth:`bytearray.fromhex`: they are now |
| 386 | between 2x and 3.5x faster. (Contributed by Victor Stinner in :issue:`25401`). |
| 387 | |
Victor Stinner | fac3956 | 2016-03-21 10:38:58 +0100 | [diff] [blame] | 388 | * Optimize ``bytes.replace(b'', b'.')`` and ``bytearray.replace(b'', b'.')``: |
| 389 | up to 80% faster. (Contributed by Josh Snider in :issue:`26574`). |
| 390 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 391 | |
| 392 | Build and C API Changes |
| 393 | ======================= |
| 394 | |
Martin Panter | b4ce1fc | 2015-11-30 03:18:29 +0000 | [diff] [blame] | 395 | * New :c:func:`Py_FinalizeEx` API which indicates if flushing buffered data |
| 396 | failed (:issue:`5319`). |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 397 | |
| 398 | |
| 399 | Deprecated |
| 400 | ========== |
| 401 | |
Yury Selivanov | 7a21911 | 2015-05-28 17:10:29 -0400 | [diff] [blame] | 402 | New Keywords |
| 403 | ------------ |
| 404 | |
Yury Selivanov | 62f27b5 | 2015-08-03 14:57:21 -0400 | [diff] [blame] | 405 | ``async`` and ``await`` are not recommended to be used as variable, class, |
| 406 | function or module names. Introduced by :pep:`492` in Python 3.5, they will |
| 407 | become proper keywords in Python 3.7. |
Yury Selivanov | 7a21911 | 2015-05-28 17:10:29 -0400 | [diff] [blame] | 408 | |
| 409 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 410 | Deprecated Python modules, functions and methods |
| 411 | ------------------------------------------------ |
| 412 | |
Brett Cannon | 9e080e0 | 2016-04-08 12:15:27 -0700 | [diff] [blame] | 413 | * :meth:`importlib.machinery.SourceFileLoader.load_module` and |
| 414 | :meth:`importlib.machinery.SourcelessFileLoader.load_module` are now |
| 415 | deprecated. They were the only remaining implementations of |
Brett Cannon | eae3079 | 2015-12-28 17:55:27 -0800 | [diff] [blame] | 416 | :meth:`importlib.abc.Loader.load_module` in :mod:`importlib` that had not |
| 417 | been deprecated in previous versions of Python in favour of |
| 418 | :meth:`importlib.abc.Loader.exec_module`. |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 419 | |
| 420 | |
| 421 | Deprecated functions and types of the C API |
| 422 | ------------------------------------------- |
| 423 | |
| 424 | * None yet. |
| 425 | |
| 426 | |
| 427 | Deprecated features |
| 428 | ------------------- |
| 429 | |
Brett Cannon | 9b63868 | 2015-10-16 15:14:27 -0700 | [diff] [blame] | 430 | * The ``pyvenv`` script has been deprecated in favour of ``python3 -m venv``. |
| 431 | This prevents confusion as to what Python interpreter ``pyvenv`` is |
| 432 | connected to and thus what Python interpreter will be used by the virtual |
Brett Cannon | 63b8505 | 2016-01-15 13:33:03 -0800 | [diff] [blame] | 433 | environment. (Contributed by Brett Cannon in :issue:`25154`.) |
| 434 | |
| 435 | * When performing a relative import, falling back on ``__name__`` and |
| 436 | ``__path__`` from the calling module when ``__spec__`` or |
| 437 | ``__package__`` are not defined now raises an :exc:`ImportWarning`. |
| 438 | (Contributed by Rose Ames in :issue:`25791`.) |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 439 | |
| 440 | |
Martin Panter | 7e3a91a | 2016-02-10 04:40:48 +0000 | [diff] [blame] | 441 | Deprecated Python behavior |
| 442 | -------------------------- |
| 443 | |
| 444 | * Raising the :exc:`StopIteration` exception inside a generator will now generate a |
| 445 | :exc:`DeprecationWarning`, and will trigger a :exc:`RuntimeError` in Python 3.7. |
| 446 | See :ref:`whatsnew-pep-479` for details. |
| 447 | |
| 448 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 449 | Removed |
| 450 | ======= |
| 451 | |
| 452 | API and Feature Removals |
| 453 | ------------------------ |
| 454 | |
Yury Selivanov | 5661316 | 2015-07-23 17:51:34 +0300 | [diff] [blame] | 455 | * ``inspect.getmoduleinfo()`` was removed (was deprecated since CPython 3.3). |
Yury Selivanov | 6dfbc5d | 2015-07-23 17:49:00 +0300 | [diff] [blame] | 456 | :func:`inspect.getmodulename` should be used for obtaining the module |
| 457 | name for a given path. |
| 458 | |
Senthil Kumaran | 613065b | 2016-01-17 20:12:16 -0800 | [diff] [blame] | 459 | * ``traceback.Ignore`` class and ``traceback.usage``, ``traceback.modname``, |
| 460 | ``traceback.fullmodname``, ``traceback.find_lines_from_code``, |
| 461 | ``traceback.find_lines``, ``traceback.find_strings``, |
| 462 | ``traceback.find_executable_lines`` methods were removed from the |
| 463 | :mod:`traceback` module. They were undocumented methods deprecated since |
| 464 | Python 3.2 and equivalent functionality is available from private methods. |
| 465 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 466 | |
| 467 | Porting to Python 3.6 |
| 468 | ===================== |
| 469 | |
| 470 | This section lists previously described changes and other bugfixes |
| 471 | that may require changes to your code. |
| 472 | |
| 473 | Changes in the Python API |
| 474 | ------------------------- |
| 475 | |
Victor Stinner | f3914eb | 2016-01-20 12:16:21 +0100 | [diff] [blame] | 476 | * The format of the ``co_lnotab`` attribute of code objects changed to support |
| 477 | negative line number delta. By default, Python does not emit bytecode with |
| 478 | negative line number delta. Functions using ``frame.f_lineno``, |
| 479 | ``PyFrame_GetLineNumber()`` or ``PyCode_Addr2Line()`` are not affected. |
| 480 | Functions decoding directly ``co_lnotab`` should be updated to use a signed |
| 481 | 8-bit integer type for the line number delta, but it's only required to |
| 482 | support applications using negative line number delta. See |
| 483 | ``Objects/lnotab_notes.txt`` for the ``co_lnotab`` format and how to decode |
| 484 | it, and see the :pep:`511` for the rationale. |
| 485 | |
Brett Cannon | 1e3c3e9 | 2015-12-27 13:17:04 -0800 | [diff] [blame] | 486 | * The functions in the :mod:`compileall` module now return booleans instead |
| 487 | of ``1`` or ``0`` to represent success or failure, respectively. Thanks to |
| 488 | booleans being a subclass of integers, this should only be an issue if you |
| 489 | were doing identity checks for ``1`` or ``0``. See :issue:`25768`. |
| 490 | |
Robert Collins | dfa95c9 | 2015-08-10 09:53:30 +1200 | [diff] [blame] | 491 | * Reading the :attr:`~urllib.parse.SplitResult.port` attribute of |
| 492 | :func:`urllib.parse.urlsplit` and :func:`~urllib.parse.urlparse` results |
| 493 | now raises :exc:`ValueError` for out-of-range values, rather than |
| 494 | returning :const:`None`. See :issue:`20059`. |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 495 | |
Brett Cannon | c0d91af | 2015-10-16 12:21:37 -0700 | [diff] [blame] | 496 | * The :mod:`imp` module now raises a :exc:`DeprecationWarning` instead of |
| 497 | :exc:`PendingDeprecationWarning`. |
| 498 | |
Martin Panter | 28a465c | 2015-11-14 12:52:08 +0000 | [diff] [blame] | 499 | * The following modules have had missing APIs added to their :attr:`__all__` |
Martin Panter | e8afd01 | 2016-01-16 07:01:46 +0000 | [diff] [blame] | 500 | attributes to match the documented APIs: :mod:`calendar`, :mod:`csv`, |
Martin Panter | dcfebb3 | 2016-04-01 06:55:55 +0000 | [diff] [blame] | 501 | :mod:`~xml.etree.ElementTree`, :mod:`enum`, |
| 502 | :mod:`fileinput`, :mod:`ftplib`, :mod:`logging`, |
Martin Panter | 528619b | 2016-04-16 23:42:37 +0000 | [diff] [blame] | 503 | :mod:`optparse`, :mod:`subprocess`, :mod:`tarfile`, :mod:`threading` and |
Martin Panter | 28a465c | 2015-11-14 12:52:08 +0000 | [diff] [blame] | 504 | :mod:`wave`. This means they will export new symbols when ``import *`` |
| 505 | is used. See :issue:`23883`. |
| 506 | |
Brett Cannon | 849113a | 2016-01-22 15:25:50 -0800 | [diff] [blame] | 507 | * When performing a relative import, if ``__package__`` does not compare equal |
| 508 | to ``__spec__.parent`` then :exc:`ImportWarning` is raised. |
| 509 | (Contributed by Brett Cannon in :issue:`25791`.) |
Brett Cannon | 63b8505 | 2016-01-15 13:33:03 -0800 | [diff] [blame] | 510 | |
Brett Cannon | 9fa8126 | 2016-01-22 16:39:02 -0800 | [diff] [blame] | 511 | * When a relative import is performed and no parent package is known, then |
| 512 | :exc:`ImportError` will be raised. Previously, :exc:`SystemError` could be |
Martin Panter | d9108d1 | 2016-02-21 08:49:56 +0000 | [diff] [blame] | 513 | raised. (Contributed by Brett Cannon in :issue:`18018`.) |
| 514 | |
| 515 | * Servers based on the :mod:`socketserver` module, including those |
| 516 | defined in :mod:`http.server`, :mod:`xmlrpc.server` and |
| 517 | :mod:`wsgiref.simple_server`, now only catch exceptions derived |
| 518 | from :exc:`Exception`. Therefore if a request handler raises |
| 519 | an exception like :exc:`SystemExit` or :exc:`KeyboardInterrupt`, |
| 520 | :meth:`~socketserver.BaseServer.handle_error` is no longer called, and |
| 521 | the exception will stop a single-threaded server. (Contributed by |
| 522 | Martin Panter in :issue:`23430`.) |
Brett Cannon | 9fa8126 | 2016-01-22 16:39:02 -0800 | [diff] [blame] | 523 | |
Berker Peksag | 3c3d7f4 | 2016-03-19 11:44:17 +0200 | [diff] [blame] | 524 | * :func:`spwd.getspnam` now raises a :exc:`PermissionError` instead of |
| 525 | :exc:`KeyError` if the user doesn't have privileges. |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 526 | |
Martin Panter | 50ab1a3 | 2016-04-11 00:38:12 +0000 | [diff] [blame] | 527 | * The :meth:`socket.socket.close` method now raises an exception if |
| 528 | an error (e.g. EBADF) was reported by the underlying system call. |
| 529 | See :issue:`26685`. |
| 530 | |
Yury Selivanov | d1da507 | 2015-05-27 22:09:10 -0400 | [diff] [blame] | 531 | Changes in the C API |
| 532 | -------------------- |
| 533 | |
Martin Panter | b4ce1fc | 2015-11-30 03:18:29 +0000 | [diff] [blame] | 534 | * :c:func:`Py_Exit` (and the main interpreter) now override the exit status |
| 535 | with 120 if flushing buffered data failed. See :issue:`5319`. |