Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1 | **************************** |
| 2 | What's New In Python 3.4 |
| 3 | **************************** |
| 4 | |
Georg Brandl | 3b80d34 | 2012-10-28 13:37:54 +0100 | [diff] [blame] | 5 | .. :Author: Someone <email> |
| 6 | (uncomment if there is a principal author) |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 7 | |
| 8 | .. Rules for maintenance: |
| 9 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 10 | * Anyone can add text to this document, but the maintainer reserves the |
| 11 | right to rewrite any additions. In particular, for obscure or esoteric |
| 12 | features, the maintainer may reduce any addition to a simple reference to |
| 13 | the new documentation rather than explaining the feature inline. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 14 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 15 | * While the maintainer will periodically go through Misc/NEWS |
| 16 | and add changes, it's best not to rely on this. We know from experience |
| 17 | that any changes that aren't in the What's New documentation around the |
| 18 | time of the original release will remain largely unknown to the community |
| 19 | for years, even if they're added later. We also know from experience that |
| 20 | other priorities can arise, and the maintainer will run out of time to do |
| 21 | updates - in such cases, end users will be much better served by partial |
| 22 | notifications that at least give a hint about new features to |
| 23 | investigate. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 24 | |
| 25 | * This is not a complete list of every single change; completeness |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 26 | is the purpose of Misc/NEWS. The What's New should focus on changes that |
| 27 | are visible to Python *users* and that *require* a feature release (i.e. |
| 28 | most bug fixes should only be recorded in Misc/NEWS) |
| 29 | |
| 30 | * PEPs should not be marked Final until they have an entry in What's New. |
| 31 | A placeholder entry that is just a section header and a link to the PEP |
| 32 | (e.g ":pep:`397` has been implemented") is acceptable. If a PEP has been |
| 33 | implemented and noted in What's New, don't forget to mark it as Final! |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 34 | |
| 35 | * If you want to draw your new text to the attention of the |
| 36 | maintainer, add 'XXX' to the beginning of the paragraph or |
| 37 | section. |
| 38 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 39 | * It's OK to add just a very brief note about a change. For |
| 40 | example: "The :ref:`~socket.transmogrify()` function was added to the |
| 41 | :mod:`socket` module." The maintainer will research the change and |
| 42 | write the necessary text (if appropriate). The advantage of doing this |
| 43 | is that even if no more descriptive text is ever added, readers will at |
| 44 | least have a notification that the new feature exists and a link to the |
| 45 | relevant documentation. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 46 | |
| 47 | * You can comment out your additions if you like, but it's not |
| 48 | necessary (especially when a final release is some months away). |
| 49 | |
| 50 | * Credit the author of a patch or bugfix. Just the name is |
| 51 | sufficient; the e-mail address isn't necessary. |
| 52 | |
| 53 | * It's helpful to add the bug/patch number as a comment: |
| 54 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 55 | The :ref:`~socket.transmogrify()` function was added to the |
| 56 | :mod:`socket` module. (Contributed by P.Y. Developer in :issue:`12345`.) |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 57 | |
| 58 | This saves the maintainer the effort of going through the Mercurial log |
| 59 | when researching a change. |
| 60 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 61 | * Cross referencing tip: :ref:`mod.attr` will display as ``mod.attr``, |
| 62 | while :ref:`~mod.attr` will display as ``attr``. |
| 63 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 64 | This article explains the new features in Python 3.4, compared to 3.3. |
| 65 | |
Nick Coghlan | 03074fd | 2012-09-30 18:51:53 +0530 | [diff] [blame] | 66 | .. Python 3.4 was released on TBD. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 67 | |
Ezio Melotti | 25bbe5e | 2012-11-17 19:30:48 +0200 | [diff] [blame] | 68 | For full details, see the |
| 69 | `changelog <http://docs.python.org/3.4/whatsnew/changelog.html>`_. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 70 | |
| 71 | .. note:: Prerelease users should be aware that this document is currently in |
| 72 | draft form. It will be updated substantially as Python 3.4 moves towards |
| 73 | release, so it's worth checking back even after reading earlier versions. |
| 74 | |
| 75 | |
| 76 | .. seealso:: |
| 77 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 78 | :pep:`429` - Python 3.4 Release Schedule |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 79 | |
| 80 | |
| 81 | Summary -- Release highlights |
| 82 | ============================= |
| 83 | |
Kristjan Valur Jonsson | a1e8244 | 2013-03-26 13:56:14 +0000 | [diff] [blame] | 84 | .. This section singles out the most important changes in Python 3.4. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 85 | Brevity is key. |
| 86 | |
| 87 | New syntax features: |
| 88 | |
R David Murray | e0f7a78 | 2013-12-20 16:04:29 -0500 | [diff] [blame] | 89 | * No new syntax features were added in Python 3.4. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 90 | |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 91 | New expected features for Python implementations: |
| 92 | |
R David Murray | 6879066 | 2013-12-23 11:17:51 -0500 | [diff] [blame] | 93 | * :ref:`pip should always be "available" <whatsnew-pep-453>` (:pep:`453`). |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 94 | * :ref:`Make newly created file descriptors non-inheritable <whatsnew-pep-446>` |
| 95 | (:pep:`446`). |
| 96 | * command line option for :ref:`isolated mode <using-on-misc-options>`, |
| 97 | (:issue:`16499`). |
R David Murray | 8d85678 | 2013-12-23 10:28:57 -0500 | [diff] [blame] | 98 | * :ref:`improvements in the handling of codecs <codec-handling-improvements>` |
| 99 | that are not text encodings (multiple issues). |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 100 | * :ref:`A ModuleSpec Type <whatsnew-pep-451>` for the Import System |
R David Murray | e9b74d4 | 2013-12-22 21:05:04 -0500 | [diff] [blame] | 101 | (:pep:`451`). (Affects importer authors.) |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 102 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 103 | New library modules: |
| 104 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 105 | * :mod:`asyncio`: :ref:`New provisional API for asynchronous IO |
| 106 | <whatsnew-asyncio>` (:pep:`3156`). |
| 107 | * :mod:`ensurepip`: :ref:`Bootstrapping the pip installer <whatsnew-ensurepip>` |
| 108 | (:pep:`453`). |
| 109 | * :mod:`enum`: :ref:`Support for enumeration types <whatsnew-enum>` |
| 110 | (:pep:`435`). |
| 111 | * :mod:`pathlib`: :ref:`Object-oriented filesystem paths <whatsnew-pathlib>` |
| 112 | (:pep:`428`). |
R David Murray | f9976e7 | 2013-12-23 10:32:02 -0500 | [diff] [blame] | 113 | * :mod:`selectors`: :ref:`High-level and efficient I/O multiplexing |
| 114 | <whatsnew-selectors>`, built upon the :mod:`select` module primitives (part |
| 115 | of :pep:`3156`). |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 116 | * :mod:`statistics`: A basic :ref:`numerically stable statistics library |
| 117 | <whatsnew-statistics>` (:pep:`450`). |
| 118 | * :mod:`tracemalloc`: :ref:`Trace Python memory allocations |
| 119 | <whatsnew-tracemalloc>` (:pep:`454`). |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 120 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 121 | Significantly Improved Library Modules: |
| 122 | |
R David Murray | 0a10216 | 2013-12-20 15:00:54 -0500 | [diff] [blame] | 123 | * :ref:`Single-dispatch generic functions <whatsnew-singledispatch>` in |
R David Murray | 8d85678 | 2013-12-23 10:28:57 -0500 | [diff] [blame] | 124 | :mod:`functools` (:pep:`443`). |
| 125 | * New :mod:`pickle` :ref:`protocol 4 <whatsnew-protocol-4>` (:pep:`3154`). |
| 126 | * :ref:`SHA-3 (Keccak) support <whatsnew-sha3>` for :mod:`hashlib` |
| 127 | (:issue:`16113`). |
| 128 | * :ref:`TLSv1.1 and TLSv1.2 support <whatsnew-tls-11-12>` for :mod:`ssl` |
| 129 | (:issue:`16692`). |
R David Murray | ac18622 | 2013-12-20 17:23:57 -0500 | [diff] [blame] | 130 | * :mod:`multiprocessing` now has :ref:`an option to avoid using os.fork |
| 131 | on Unix <whatsnew-multiprocessing-no-fork>` (:issue:`8713`). |
R David Murray | 6adb454 | 2013-12-20 13:10:43 -0500 | [diff] [blame] | 132 | * :mod:`email` has a new submodule, :mod:`~email.contentmanager`, and |
| 133 | a new :mod:`~email.message.Message` subclass |
R David Murray | 26b80cfd | 2013-12-20 17:26:52 -0500 | [diff] [blame] | 134 | (:class:`~email.contentmanager.EmailMessage`) that :ref:`simplify MIME |
R David Murray | 8d85678 | 2013-12-23 10:28:57 -0500 | [diff] [blame] | 135 | handling <whatsnew_email_contentmanager>` (:issue:`18891`). |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 136 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 137 | CPython implementation improvements: |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 138 | |
R David Murray | a93ca97 | 2013-12-22 14:10:21 -0500 | [diff] [blame] | 139 | * :ref:`Safe object finalization <whatsnew-pep-442>` (:pep:`442`). |
R David Murray | ca79461 | 2013-12-22 14:05:11 -0500 | [diff] [blame] | 140 | * Leveraging :pep:`442`, :ref:`module globals are no longer set to None |
| 141 | during finalization <whatsnew-pep-442>`, in most cases (:issue:`18214`). |
R David Murray | a93ca97 | 2013-12-22 14:10:21 -0500 | [diff] [blame] | 142 | * :ref:`Configurable memory allocators <whatsnew-pep-445>` (:pep:`445`). |
| 143 | * :ref:`Secure and interchangeable hash algorithm <whatsnew-pep-456>` |
| 144 | (:pep:`456`). |
| 145 | * :ref:`Argument Clinic <whatsnew-pep-436>` (:pep:`436`). |
R David Murray | 8f7664a | 2013-12-22 20:40:11 -0500 | [diff] [blame] | 146 | * The :mod:`marshal` format has been made :ref:`more compact and efficient |
| 147 | <whatsnew-marshal-3>` (:issue:`16475`). |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 148 | |
R David Murray | 347f9c7 | 2013-12-23 21:30:06 -0500 | [diff] [blame] | 149 | Please read on for a comprehensive list of user-facing changes, including many |
| 150 | other smaller improvements, CPython optimizations, deprecations, and potential |
| 151 | porting issues. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 152 | |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 153 | |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 154 | New expected features for Python implementations |
| 155 | ================================================ |
| 156 | |
R David Murray | 6879066 | 2013-12-23 11:17:51 -0500 | [diff] [blame] | 157 | .. _whatsnew-pep-453: |
| 158 | |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 159 | PEP 453: Explicit bootstrapping of pip in Python installations |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 160 | -------------------------------------------------------------- |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 161 | |
| 162 | The new :mod:`ensurepip` module (defined in :pep:`453`) provides a standard |
| 163 | cross-platform mechanism to boostrap the pip installer into Python |
| 164 | installations and virtual environments. |
| 165 | |
Nick Coghlan | 7bc4b3b | 2013-11-23 11:59:40 +1000 | [diff] [blame] | 166 | The :mod:`venv` module and the :command:`pyvenv` utility make use of this |
| 167 | module to make ``pip`` readily available in virtual environments. When |
| 168 | using the command line interface, ``pip`` is installed by default, while |
| 169 | for the module API installation of ``pip`` must be requested explicitly. |
| 170 | |
| 171 | For CPython source builds on POSIX systems, the ``make install`` and |
| 172 | ``make altinstall`` commands bootstrap ``pip`` by default. This behaviour |
| 173 | can be controlled through configure options, and overridden through |
| 174 | Makefile options. |
| 175 | |
Ned Deily | 44a0db0 | 2013-11-22 22:39:09 -0800 | [diff] [blame] | 176 | On Windows and Mac OS X, the CPython installers now offer the option to |
| 177 | install ``pip`` along with CPython itself. |
Nick Coghlan | 7bc4b3b | 2013-11-23 11:59:40 +1000 | [diff] [blame] | 178 | |
R David Murray | 6879066 | 2013-12-23 11:17:51 -0500 | [diff] [blame] | 179 | As `discussed in the PEP`__, platform packagers may choose not to install |
| 180 | ``pip`` by default, as long as the command ``pip``, when invoked, provides |
| 181 | clear and simple directions on how to install ``pip`` on the platform. |
| 182 | |
| 183 | __ http://www.python.org/dev/peps/pep-0453/#recommendations-for-downstream-distributors |
| 184 | |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 185 | .. note:: |
| 186 | |
Nick Coghlan | 7bc4b3b | 2013-11-23 11:59:40 +1000 | [diff] [blame] | 187 | The implementation of PEP 453 is still a work in progress. Refer to |
| 188 | :issue:`19347` for the progress on additional steps: |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 189 | |
Nick Coghlan | 7bc4b3b | 2013-11-23 11:59:40 +1000 | [diff] [blame] | 190 | * Having the binary installers install ``pip`` by default |
| 191 | * Recommending the use of ``pip`` in the "Installing Python Module" |
| 192 | documentation. |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 193 | |
| 194 | .. seealso:: |
| 195 | |
| 196 | :pep:`453` - Explicit bootstrapping of pip in Python installations |
| 197 | PEP written by Donald Stufft and Nick Coghlan, implemented by |
Nick Coghlan | 7bc4b3b | 2013-11-23 11:59:40 +1000 | [diff] [blame] | 198 | Donald Stufft, Nick Coghlan, Martin von Löwis and Ned Deily. |
Nick Coghlan | d0cf063 | 2013-11-11 22:11:55 +1000 | [diff] [blame] | 199 | |
| 200 | |
R David Murray | f9909c2 | 2013-12-20 14:50:12 -0500 | [diff] [blame] | 201 | .. _whatsnew-pep-446: |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 202 | |
| 203 | PEP 446: Make newly created file descriptors non-inheritable |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 204 | ------------------------------------------------------------ |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 205 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 206 | :pep:`446` makes newly created file descriptors :ref:`non-inheritable |
Georg Brandl | 5642ff9 | 2013-09-15 10:37:57 +0200 | [diff] [blame] | 207 | <fd_inheritance>`. New functions and methods: |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 208 | |
| 209 | * :func:`os.get_inheritable`, :func:`os.set_inheritable` |
| 210 | * :func:`os.get_handle_inheritable`, :func:`os.set_handle_inheritable` |
| 211 | * :meth:`socket.socket.get_inheritable`, :meth:`socket.socket.set_inheritable` |
| 212 | |
Antoine Pitrou | 796564c | 2013-07-30 19:59:21 +0200 | [diff] [blame] | 213 | .. seealso:: |
| 214 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 215 | :pep:`446` - Make newly created file descriptors non-inheritable |
| 216 | PEP written and implemented by Victor Stinner. |
Antoine Pitrou | 796564c | 2013-07-30 19:59:21 +0200 | [diff] [blame] | 217 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 218 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 219 | .. _codec-handling-improvements: |
| 220 | |
| 221 | Improvements to codec handling |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 222 | ------------------------------ |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 223 | |
| 224 | Since it was first introduced, the :mod:`codecs` module has always been |
| 225 | intended to operate as a type-neutral dynamic encoding and decoding |
| 226 | system. However, its close coupling with the Python text model, especially |
| 227 | the type restricted convenience methods on the builtin :class:`str`, |
| 228 | :class:`bytes` and :class:`bytearray` types, has historically obscured that |
| 229 | fact. |
| 230 | |
| 231 | As a key step in clarifying the situation, the :meth:`codecs.encode` and |
| 232 | :meth:`codecs.decode` convenience functions are now properly documented in |
| 233 | Python 2.7, 3.3 and 3.4. These functions have existed in the :mod:`codecs` |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 234 | module (and have been covered by the regression test suite) since Python 2.4, |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 235 | but were previously only discoverable through runtime introspection. |
| 236 | |
| 237 | Unlike the convenience methods on :class:`str`, :class:`bytes` and |
| 238 | :class:`bytearray`, these convenience functions support arbitrary codecs |
| 239 | in both Python 2 and Python 3, rather than being limited to Unicode text |
| 240 | encodings (in Python 3) or ``basestring`` <-> ``basestring`` conversions |
| 241 | (in Python 2). |
| 242 | |
Nick Coghlan | 8afc8f6 | 2013-11-22 23:00:22 +1000 | [diff] [blame] | 243 | In Python 3.4, the interpreter is able to identify the known non-text |
| 244 | encodings provided in the standard library and direct users towards these |
| 245 | general purpose convenience functions when appropriate:: |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 246 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 247 | >>> b"abcdef".decode("hex") |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 248 | Traceback (most recent call last): |
| 249 | File "<stdin>", line 1, in <module> |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 250 | LookupError: 'hex' is not a text encoding; use codecs.decode() to handle arbitrary codecs |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 251 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 252 | >>> "hello".encode("rot13") |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 253 | Traceback (most recent call last): |
| 254 | File "<stdin>", line 1, in <module> |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 255 | LookupError: 'rot13' is not a text encoding; use codecs.encode() to handle arbitrary codecs |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 256 | |
| 257 | In a related change, whenever it is feasible without breaking backwards |
| 258 | compatibility, exceptions raised during encoding and decoding operations |
| 259 | will be wrapped in a chained exception of the same type that mentions the |
| 260 | name of the codec responsible for producing the error:: |
| 261 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 262 | >>> import codecs |
| 263 | |
| 264 | >>> codecs.decode(b"abcdefgh", "hex") |
Nick Coghlan | 8afc8f6 | 2013-11-22 23:00:22 +1000 | [diff] [blame] | 265 | binascii.Error: Non-hexadecimal digit found |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 266 | |
| 267 | The above exception was the direct cause of the following exception: |
| 268 | |
| 269 | Traceback (most recent call last): |
| 270 | File "<stdin>", line 1, in <module> |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 271 | binascii.Error: decoding with 'hex' codec failed (Error: Non-hexadecimal digit found) |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 272 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 273 | >>> codecs.encode("hello", "bz2") |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 274 | TypeError: 'str' does not support the buffer interface |
| 275 | |
| 276 | The above exception was the direct cause of the following exception: |
| 277 | |
| 278 | Traceback (most recent call last): |
| 279 | File "<stdin>", line 1, in <module> |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 280 | TypeError: encoding with 'bz2' codec failed (TypeError: 'str' does not support the buffer interface) |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 281 | |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 282 | Finally, as the examples above show, these improvements have permitted |
| 283 | the restoration of the convenience aliases for the non-Unicode codecs that |
| 284 | were themselves restored in Python 3.2. This means that encoding binary data |
| 285 | to and from its hexadecimal representation (for example) can now be written |
| 286 | as:: |
| 287 | |
| 288 | >>> from codecs import encode, decode |
| 289 | >>> encode(b"hello", "hex") |
| 290 | b'68656c6c6f' |
| 291 | >>> decode(b"68656c6c6f", "hex") |
| 292 | b'hello' |
| 293 | |
| 294 | The binary and text transforms provided in the standard library are detailed |
| 295 | in :ref:`binary-transforms` and :ref:`text-transforms`. |
| 296 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 297 | (Contributed by Nick Coghlan in :issue:`7475`, , :issue:`17827`, |
Nick Coghlan | 9c1aed8 | 2013-11-23 11:13:36 +1000 | [diff] [blame] | 298 | :issue:`17828` and :issue:`19619`) |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 299 | |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 300 | .. _whatsnew-pep-451: |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 301 | |
| 302 | PEP 451: A ModuleSpec Type for the Import System |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 303 | ------------------------------------------------ |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 304 | |
R David Murray | f85b2a8 | 2013-12-22 21:06:13 -0500 | [diff] [blame] | 305 | :pep:`451` provides an encapsulation of the information about a module that the |
| 306 | import machinery will use to load it (that is, a module specification). This |
| 307 | helps simplify both the import implementation and several import-related APIs. |
| 308 | The change is also a stepping stone for `several future import-related |
| 309 | improvements`__. |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 310 | |
R David Murray | e9b74d4 | 2013-12-22 21:05:04 -0500 | [diff] [blame] | 311 | __ https://mail.python.org/pipermail/python-dev/2013-November/130111.html |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 312 | |
| 313 | The public-facing changes from the PEP are entirely backward-compatible. |
R David Murray | f85b2a8 | 2013-12-22 21:06:13 -0500 | [diff] [blame] | 314 | Furthermore, they should be transparent to everyone but importer authors. Key |
| 315 | finder and loader methods have been deprecated, but they will continue working. |
| 316 | New importers should use the new methods described in the PEP. Existing |
| 317 | importers should be updated to implement the new methods. |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 318 | |
Nick Coghlan | 8b097b4 | 2013-11-13 23:49:21 +1000 | [diff] [blame] | 319 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 320 | Other Language Changes |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 321 | ---------------------- |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 322 | |
| 323 | Some smaller changes made to the core Python language are: |
| 324 | |
Ezio Melotti | 34808e2 | 2013-10-12 16:36:13 +0300 | [diff] [blame] | 325 | * Unicode database updated to UCD version 6.3. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 326 | |
R David Murray | 9a2f139 | 2013-06-28 13:31:19 -0400 | [diff] [blame] | 327 | * :func:`min` and :func:`max` now accept a *default* argument that can be used |
| 328 | to specify the value they return if the iterable they are evaluating has no |
| 329 | elements. Contributed by Julian Berman in :issue:`18111`. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 330 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 331 | * Module objects are now :mod:`weakref`'able. |
| 332 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 333 | * Module ``__file__`` attributes (and related values) should now always |
| 334 | contain absolute paths by default, with the sole exception of |
| 335 | ``__main__.__file__`` when a script has been executed directly using |
| 336 | a relative path (Contributed by Brett Cannon in :issue:`18416`). |
| 337 | |
Serhiy Storchaka | 58cf607 | 2013-11-19 11:32:41 +0200 | [diff] [blame] | 338 | * Now all the UTF-\* codecs (except UTF-7) reject surrogates during both |
| 339 | encoding and decoding unless the ``surrogatepass`` error handler is used, |
| 340 | with the exception of the UTF-16 decoder that accepts valid surrogate pairs, |
| 341 | and the UTF-16 encoder that produces them while encoding non-BMP characters. |
| 342 | Contributed by Victor Stinner, Kang-Hao (Kenny) Lu and Serhiy Storchaka in |
| 343 | :issue:`12892`. |
| 344 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 345 | |
| 346 | New Modules |
| 347 | =========== |
| 348 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 349 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 350 | .. _whatsnew-asyncio: |
| 351 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 352 | asyncio |
| 353 | ------- |
| 354 | |
| 355 | The new :mod:`asyncio` module (defined in :pep:`3156`) provides a standard |
| 356 | pluggable event loop model for Python, providing solid asynchronous IO |
| 357 | support in the standard library, and making it easier for other event loop |
| 358 | implementations to interoperate with the standard library and each other. |
| 359 | |
| 360 | For Python 3.4, this module is considered a :term:`provisional API`. |
| 361 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 362 | .. seealso:: |
| 363 | |
| 364 | :pep:`3156` - Asynchronous IO Support Rebooted: the "asyncio" Module |
| 365 | PEP written and implementation led by Guido van Rossum. |
| 366 | |
R David Murray | 6879066 | 2013-12-23 11:17:51 -0500 | [diff] [blame] | 367 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 368 | .. _whatsnew-ensurepip: |
R David Murray | 6879066 | 2013-12-23 11:17:51 -0500 | [diff] [blame] | 369 | |
| 370 | ensurepip |
| 371 | --------- |
| 372 | |
| 373 | The new :mod:`ensurepip` module is the primary infrastructure for the |
| 374 | :pep:`453` implementation. In the normal course of events end users will not |
| 375 | need to interact with this module, but it can be used to manually bootstrap |
| 376 | ``pip`` if the automated bootstrapping into an installation or virtual |
| 377 | environment was declined. |
| 378 | |
| 379 | :mod:`ensurepip` includes a bundled copy of ``pip``, up-to-date as of the first |
| 380 | release candidate of the release of CPython with which it ships (this applies |
| 381 | to both maintenance releases and feature releases). ``ensurepip`` does not |
| 382 | access the internet. (If the installation has Internet access, it is of course |
| 383 | possible to upgrade ``pip`` to a release more recent than the bundled ``pip`` |
| 384 | by using the bundled ``pip`` command itself once it is installed.) |
| 385 | |
| 386 | The module is named *ensure*\ pip because if called when ``pip`` is already |
| 387 | installed, it does nothing. It also has an ``--upgrade`` option that will |
| 388 | cause it to install the bundled copy of ``pip`` if the existing installed |
| 389 | version of ``pip`` is older than the bundled copy. |
| 390 | |
| 391 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 392 | .. _whatsnew-enum: |
| 393 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 394 | enum |
| 395 | ---- |
| 396 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 397 | The new :mod:`enum` module (defined in :pep:`435`) provides a standard |
| 398 | implementation of enumeration types, allowing other modules (such as |
| 399 | :mod:`socket`) to provide more informative error messages and better |
| 400 | debugging support by replacing opaque integer constants with backwards |
| 401 | compatible enumeration values. |
| 402 | |
| 403 | .. seealso:: |
| 404 | |
| 405 | :pep:`435` - Adding an Enum type to the Python standard library |
| 406 | PEP written by Barry Warsaw, Eli Bendersky and Ethan Furman, |
| 407 | implemented by Ethan Furman. |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 408 | |
| 409 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 410 | .. _whatsnew-pathlib: |
| 411 | |
Antoine Pitrou | 31119e4 | 2013-11-22 17:38:12 +0100 | [diff] [blame] | 412 | pathlib |
| 413 | ------- |
| 414 | |
| 415 | The new :mod:`pathlib` module offers classes representing filesystem paths |
| 416 | with semantics appropriate for different operating systems. Path classes are |
| 417 | divided between *pure paths*, which provide purely computational operations |
| 418 | without I/O, and *concrete paths*, which inherit from pure paths but also |
| 419 | provide I/O operations. |
| 420 | |
| 421 | For Python 3.4, this module is considered a :term:`provisional API`. |
| 422 | |
| 423 | .. seealso:: |
| 424 | |
| 425 | :pep:`428` - The pathlib module -- object-oriented filesystem paths |
| 426 | PEP written and implemented by Antoine Pitrou. |
| 427 | |
| 428 | |
R David Murray | f9976e7 | 2013-12-23 10:32:02 -0500 | [diff] [blame] | 429 | .. _whatsnew-selectors: |
| 430 | |
Charles-François Natali | 243d8d8 | 2013-09-04 19:02:49 +0200 | [diff] [blame] | 431 | selectors |
| 432 | --------- |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 433 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 434 | The new :mod:`selectors` module (created as part of implementing :pep:`3156`) |
| 435 | allows high-level and efficient I/O multiplexing, built upon the |
| 436 | :mod:`select` module primitives. |
| 437 | |
| 438 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 439 | .. _whatsnew-statistics: |
| 440 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 441 | statistics |
| 442 | ---------- |
| 443 | |
| 444 | The new :mod:`statistics` module (defined in :pep:`450`) offers some core |
| 445 | statistics functionality directly in the standard library. This module |
| 446 | supports calculation of the mean, median, mode, variance and standard |
| 447 | deviation of a data series. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 448 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 449 | .. seealso:: |
| 450 | |
| 451 | :pep:`450` - Adding A Statistics Module To The Standard Library |
| 452 | PEP written and implemented by Steven D'Aprano |
| 453 | |
R David Murray | 9217dad | 2013-12-23 21:08:28 -0500 | [diff] [blame] | 454 | .. _whatsnew-tracemalloc: |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 455 | |
Victor Stinner | d2736af | 2013-11-25 09:40:27 +0100 | [diff] [blame] | 456 | tracemalloc |
| 457 | ----------- |
| 458 | |
| 459 | The new :mod:`tracemalloc` module (defined in :pep:`454`) is a debug tool to |
| 460 | trace memory blocks allocated by Python. It provides the following information: |
| 461 | |
| 462 | * Traceback where an object was allocated |
| 463 | * Statistics on allocated memory blocks per filename and per line number: |
| 464 | total size, number and average size of allocated memory blocks |
| 465 | * Compute the differences between two snapshots to detect memory leaks |
| 466 | |
| 467 | .. seealso:: |
| 468 | |
| 469 | :pep:`454` - Add a new tracemalloc module to trace Python memory allocations |
| 470 | PEP written and implemented by Victor Stinner |
| 471 | |
| 472 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 473 | Improved Modules |
| 474 | ================ |
| 475 | |
R David Murray | 72420ff | 2013-12-24 10:46:44 -0500 | [diff] [blame^] | 476 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 477 | aifc |
| 478 | ---- |
| 479 | |
| 480 | The :meth:`~aifc.getparams` method now returns a namedtuple rather than a |
| 481 | plain tuple. (Contributed by Claudiu Popa in :issue:`17818`.) |
| 482 | |
| 483 | |
Serhiy Storchaka | eaea5e9 | 2013-10-19 21:10:46 +0300 | [diff] [blame] | 484 | audioop |
| 485 | ------- |
| 486 | |
| 487 | Added support for 24-bit samples (:issue:`12866`). |
| 488 | |
Serhiy Storchaka | 3062c9a | 2013-11-23 22:26:01 +0200 | [diff] [blame] | 489 | Added the :func:`~audioop.byteswap` function to convert big-endian samples |
| 490 | to little-endian and vice versa (:issue:`19641`). |
| 491 | |
Serhiy Storchaka | eaea5e9 | 2013-10-19 21:10:46 +0300 | [diff] [blame] | 492 | |
Nick Coghlan | d4fdbcc | 2013-11-14 00:24:31 +1000 | [diff] [blame] | 493 | base64 |
| 494 | ------ |
| 495 | |
| 496 | The encoding and decoding functions in :mod:`base64` now accept any |
| 497 | :term:`bytes-like object` in cases where it previously required a |
Georg Brandl | ed007d5 | 2013-11-24 16:09:26 +0100 | [diff] [blame] | 498 | :class:`bytes` or :class:`bytearray` instance (:issue:`17839`). |
Nick Coghlan | d4fdbcc | 2013-11-14 00:24:31 +1000 | [diff] [blame] | 499 | |
| 500 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 501 | colorsys |
| 502 | -------- |
| 503 | |
| 504 | The number of digits in the coefficients for the RGB --- YIQ conversions have |
| 505 | been expanded so that they match the FCC NTSC versions. The change in |
| 506 | results should be less than 1% and may better match results found elsewhere. |
| 507 | |
R David Murray | 8e37d5d | 2013-04-13 14:49:48 -0400 | [diff] [blame] | 508 | |
Nick Coghlan | b4534ae | 2013-10-13 23:23:08 +1000 | [diff] [blame] | 509 | contextlib |
| 510 | ---------- |
| 511 | |
Nick Coghlan | 240f86d | 2013-10-17 23:40:57 +1000 | [diff] [blame] | 512 | The new :class:`contextlib.suppress` context manager helps to clarify the |
| 513 | intent of code that deliberately suppresses exceptions from a single |
| 514 | statement. (Contributed by Raymond Hettinger in :issue:`15806` and |
| 515 | Zero Piraeus in :issue:`19266`) |
| 516 | |
Victor Stinner | 6633c39 | 2013-10-21 13:27:11 +0200 | [diff] [blame] | 517 | The new :func:`contextlib.redirect_stdout` context manager makes it easier |
Nick Coghlan | b4534ae | 2013-10-13 23:23:08 +1000 | [diff] [blame] | 518 | for utility scripts to handle inflexible APIs that don't provide any |
| 519 | options to retrieve their output as a string or direct it to somewhere |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 520 | other than :data:`sys.stdout`. In conjunction with :class:`io.StringIO`, |
| 521 | this context manager is also useful for checking expected output from |
| 522 | command line utilities. (Contribute by Raymond Hettinger in :issue:`15805`) |
| 523 | |
| 524 | The :mod:`contextlib` documentation has also been updated to include a |
| 525 | :ref:`discussion <single-use-reusable-and-reentrant-cms>` of the |
| 526 | differences between single use, reusable and reentrant context managers. |
Nick Coghlan | b4534ae | 2013-10-13 23:23:08 +1000 | [diff] [blame] | 527 | |
| 528 | |
Nick Coghlan | b39fd0c | 2013-05-06 23:59:20 +1000 | [diff] [blame] | 529 | dis |
| 530 | --- |
| 531 | |
Serhiy Storchaka | 98b28fd | 2013-10-13 23:12:09 +0300 | [diff] [blame] | 532 | The :mod:`dis` module is now built around an :class:`~dis.Instruction` class |
| 533 | that provides details of individual bytecode operations and a |
| 534 | :func:`~dis.get_instructions` iterator that emits the Instruction stream for a |
Nick Coghlan | b39fd0c | 2013-05-06 23:59:20 +1000 | [diff] [blame] | 535 | given piece of Python code. The various display tools in the :mod:`dis` |
| 536 | module have been updated to be based on these new components. |
| 537 | |
| 538 | The new :class:`dis.Bytecode` class provides an object-oriented API for |
| 539 | inspecting bytecode, both in human-readable form and for iterating over |
| 540 | instructions. |
| 541 | |
Nick Coghlan | 50c48b8 | 2013-11-23 00:57:00 +1000 | [diff] [blame] | 542 | (Contributed by Nick Coghlan, Ryan Kelly and Thomas Kluyver in :issue:`11816` |
| 543 | and Claudiu Popa in :issue:`17916`) |
Nick Coghlan | b39fd0c | 2013-05-06 23:59:20 +1000 | [diff] [blame] | 544 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 545 | |
R David Murray | 5a9d706 | 2012-11-21 15:09:21 -0500 | [diff] [blame] | 546 | doctest |
| 547 | ------- |
| 548 | |
R David Murray | 5707d50 | 2013-06-23 14:24:13 -0400 | [diff] [blame] | 549 | Added :data:`~doctest.FAIL_FAST` flag to halt test running as soon as the first |
| 550 | failure is detected. (Contributed by R. David Murray and Daniel Urban in |
| 551 | :issue:`16522`.) |
| 552 | |
| 553 | Updated the doctest command line interface to use :mod:`argparse`, and added |
| 554 | ``-o`` and ``-f`` options to the interface. ``-o`` allows doctest options to |
| 555 | be specified on the command line, and ``-f`` is a shorthand for ``-o |
| 556 | FAIL_FAST`` (to parallel the similar option supported by the :mod:`unittest` |
| 557 | CLI). (Contributed by R. David Murray in :issue:`11390`.) |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 558 | |
R David Murray | 8e37d5d | 2013-04-13 14:49:48 -0400 | [diff] [blame] | 559 | |
R David Murray | bb17d2b | 2013-08-09 16:15:28 -0400 | [diff] [blame] | 560 | email |
| 561 | ----- |
| 562 | |
| 563 | :meth:`~email.message.Message.as_string` now accepts a *policy* argument to |
| 564 | override the default policy of the message when generating a string |
| 565 | representation of it. This means that ``as_string`` can now be used in more |
| 566 | circumstances, instead of having to create and use a :mod:`~email.generator` in |
| 567 | order to pass formatting parameters to its ``flatten`` method. |
| 568 | |
| 569 | New method :meth:`~email.message.Message.as_bytes` added to produce a bytes |
| 570 | representation of the message in a fashion similar to how ``as_string`` |
| 571 | produces a string representation. It does not accept the *maxheaderlen* |
| 572 | argument, but does accept the *unixfrom* and *policy* arguments. The |
| 573 | :class:`~email.message.Message` :meth:`~email.message.Message.__bytes__` method |
| 574 | calls it, meaning that ``bytes(mymsg)`` will now produce the intuitive |
| 575 | result: a bytes object containing the fully formatted message. |
| 576 | |
| 577 | (Contributed by R. David Murray in :issue:`18600`.) |
| 578 | |
R David Murray | 26b80cfd | 2013-12-20 17:26:52 -0500 | [diff] [blame] | 579 | .. _whatsnew_email_contentmanager: |
| 580 | |
R David Murray | 3da240f | 2013-10-16 22:48:40 -0400 | [diff] [blame] | 581 | A pair of new subclasses of :class:`~email.message.Message` have been added, |
| 582 | along with a new sub-module, :mod:`~email.contentmanager`. All documentation |
| 583 | is currently in the new module, which is being added as part of the new |
Nick Coghlan | 240f86d | 2013-10-17 23:40:57 +1000 | [diff] [blame] | 584 | :term:`provisional <provisional package>` email API. These classes provide a |
R David Murray | 3da240f | 2013-10-16 22:48:40 -0400 | [diff] [blame] | 585 | number of new methods that make extracting content from and inserting content |
| 586 | into email messages much easier. See the :mod:`~email.contentmanager` |
| 587 | documentation for details. |
| 588 | |
| 589 | These API additions complete the bulk of the work that was planned as part of |
| 590 | the email6 project. The currently provisional API is scheduled to become final |
| 591 | in Python 3.5 (possibly with a few minor additions in the area of error |
| 592 | handling). |
| 593 | |
| 594 | (Contributed by R. David Murray in :issue:`18891`.) |
| 595 | |
R David Murray | bb17d2b | 2013-08-09 16:15:28 -0400 | [diff] [blame] | 596 | |
Victor Stinner | 854ffcb | 2013-06-21 00:36:30 +0200 | [diff] [blame] | 597 | functools |
| 598 | --------- |
| 599 | |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 600 | The new :func:`~functools.partialmethod` descriptor bring partial argument |
| 601 | application to descriptors, just as :func:`~functools.partial` provides |
| 602 | for normal callables. The new descriptor also makes it easier to get |
| 603 | arbitrary callables (including :func:`~functools.partial` instances) |
| 604 | to behave like normal instance methods when included in a class definition. |
| 605 | |
| 606 | (Contributed by Alon Horev and Nick Coghlan in :issue:`4331`) |
| 607 | |
R David Murray | 0a10216 | 2013-12-20 15:00:54 -0500 | [diff] [blame] | 608 | .. _whatsnew-singledispatch: |
| 609 | |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 610 | The new :func:`~functools.singledispatch` decorator brings support for |
| 611 | single-dispatch generic functions to the Python standard library. Where |
| 612 | object oriented programming focuses on grouping multiple operations on a |
| 613 | common set of data into a class, a generic function focuses on grouping |
| 614 | multiple implementations of an operation that allows it to work with |
| 615 | *different* kinds of data. |
| 616 | |
| 617 | .. seealso:: |
| 618 | |
| 619 | :pep:`443` - Single-dispatch generic functions |
| 620 | PEP written and implemented by Łukasz Langa. |
Victor Stinner | 854ffcb | 2013-06-21 00:36:30 +0200 | [diff] [blame] | 621 | |
Nick Coghlan | e8c45d6 | 2013-07-28 20:00:01 +1000 | [diff] [blame] | 622 | |
Christian Heimes | e92ef13 | 2013-10-13 00:52:43 +0200 | [diff] [blame] | 623 | hashlib |
| 624 | ------- |
| 625 | |
| 626 | New :func:`hashlib.pbkdf2_hmac` function. |
Christian Heimes | e92ef13 | 2013-10-13 00:52:43 +0200 | [diff] [blame] | 627 | (Contributed by Christian Heimes in :issue:`18582`) |
| 628 | |
R David Murray | cde1a06 | 2013-12-20 16:33:52 -0500 | [diff] [blame] | 629 | .. _whatsnew-sha3: |
| 630 | |
| 631 | New :ref:`hash algorithms <hash-algorithms>` ``sah3_224()``, ``sha3_256()``, |
| 632 | ``sha3_384()``, and ``sha3_512()``. (Contributed by Christian Heimes in |
| 633 | :issue:`16113`.) |
| 634 | |
Christian Heimes | e92ef13 | 2013-10-13 00:52:43 +0200 | [diff] [blame] | 635 | |
Ezio Melotti | 250a06c | 2013-11-25 06:18:47 +0200 | [diff] [blame] | 636 | html |
| 637 | ---- |
| 638 | |
| 639 | Added a new :func:`html.unescape` function that converts HTML5 character |
| 640 | references to the corresponding Unicode characters. |
Ezio Melotti | 250a06c | 2013-11-25 06:18:47 +0200 | [diff] [blame] | 641 | (Contributed by Ezio Melotti in :issue:`2927`) |
| 642 | |
| 643 | Added a new *convert_charrefs* keyword argument to |
| 644 | :class:`~html.parser.HTMLParser` that, when ``True``, automatically converts |
| 645 | all character references. For backward-compatibility, its value defaults |
| 646 | to ``False``, but it will change to ``True`` in future versions, so you |
| 647 | are invited to set it explicitly and update your code to use this new feature. |
Ezio Melotti | 250a06c | 2013-11-25 06:18:47 +0200 | [diff] [blame] | 648 | (Contributed by Ezio Melotti in :issue:`13633`) |
| 649 | |
| 650 | The *strict* argument of :class:`~html.parser.HTMLParser` is now deprecated. |
Ezio Melotti | 250a06c | 2013-11-25 06:18:47 +0200 | [diff] [blame] | 651 | (Contributed by Ezio Melotti in :issue:`15114`) |
| 652 | |
| 653 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 654 | inspect |
| 655 | ------- |
| 656 | |
Nick Coghlan | f94a16b | 2013-09-22 22:46:49 +1000 | [diff] [blame] | 657 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 658 | The inspect module now offers a basic :ref:`command line interface |
| 659 | <inspect-module-cli>` to quickly display source code and other |
| 660 | information for modules, classes and functions. (Contributed by Claudiu Popa |
| 661 | and Nick Coghlan in :issue:`18626`) |
Nick Coghlan | f94a16b | 2013-09-22 22:46:49 +1000 | [diff] [blame] | 662 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 663 | :func:`~inspect.unwrap` makes it easy to unravel wrapper function chains |
| 664 | created by :func:`functools.wraps` (and any other API that sets the |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 665 | ``__wrapped__`` attribute on a wrapper function). (Contributed by |
| 666 | Daniel Urban, Aaron Iles and Nick Coghlan in :issue:`13266`) |
| 667 | |
| 668 | As part of the implementation of the new :mod:`enum` module, the |
| 669 | :mod:`inspect` module now has substantially better support for custom |
| 670 | ``__dir__`` methods and dynamic class attributes provided through |
| 671 | metaclasses (Contributed by Ethan Furman in :issue:`18929` and |
| 672 | :issue:`19030`) |
| 673 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 674 | |
R David Murray | 8f7664a | 2013-12-22 20:40:11 -0500 | [diff] [blame] | 675 | .. _whatsnew-marshal-3: |
| 676 | |
| 677 | marshal |
| 678 | ------- |
| 679 | |
| 680 | The default :mod:`marshal` version has been bumped to 3. The code implementing |
| 681 | the new version restores the Python2 behavior of recording only one copy of |
| 682 | interned strings and preserving the interning on deserialization, and extends |
| 683 | this "one copy" ability to any object type (including handling recursive |
| 684 | references). This reduces both the size of ``.pyc`` files and the amount of |
| 685 | memory a module occupies in memory when it is loaded from a ``.pyc`` (or |
| 686 | ``.pyo``) file. (Contributed by Kristján Valur Jónsson in :issue:`16475`.) |
| 687 | |
| 688 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 689 | mmap |
| 690 | ---- |
| 691 | |
| 692 | mmap objects can now be weakref'ed. |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 693 | (Contributed by Valerie Lambert in :issue:`4885`.) |
| 694 | |
| 695 | |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 696 | multiprocessing |
| 697 | --------------- |
| 698 | |
R David Murray | ac18622 | 2013-12-20 17:23:57 -0500 | [diff] [blame] | 699 | .. _whatsnew-multiprocessing-no-fork: |
| 700 | |
| 701 | On Unix, two new :ref:`start methods <multiprocessing-start-methods>` |
| 702 | (``spawn`` and ``forkserver``) have been added for starting processes using |
| 703 | :mod:`multiprocessing`. These make the mixing of processes with threads more |
| 704 | robust, and the ``spawn`` method matches the semantics that multiprocessing has |
| 705 | always used on Windows. (Contributed by Richard Oudkerk in :issue:`8713`). |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 706 | |
| 707 | Also, except when using the old *fork* start method, child processes |
R David Murray | ac18622 | 2013-12-20 17:23:57 -0500 | [diff] [blame] | 708 | will no longer inherit unneeded handles/file descriptors from their parents |
| 709 | (part of :issue:`8713`). |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 710 | |
Nick Coghlan | 9a76735 | 2013-12-17 22:17:26 +1000 | [diff] [blame] | 711 | :mod:`multiprocessing` now relies on :mod:`runpy` (which implements the |
| 712 | ``-m`` switch) to initialise ``__main__`` appropriately in child processes |
| 713 | when using the ``spawn`` or ``forkserver`` start methods. This resolves some |
| 714 | edge cases where combining multiprocessing, the ``-m`` command line switch |
| 715 | and explicit relative imports could cause obscure failures in child |
| 716 | processes. (Contributed by Nick Coghlan in :issue:`19946`) |
| 717 | |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 718 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 719 | os |
| 720 | -- |
| 721 | |
Georg Brandl | c6ebbef | 2013-09-16 04:03:12 +0200 | [diff] [blame] | 722 | New functions to get and set the :ref:`inheritable flag <fd_inheritance>` of a file |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 723 | descriptors or a Windows handle: |
| 724 | |
| 725 | * :func:`os.get_inheritable`, :func:`os.set_inheritable` |
| 726 | * :func:`os.get_handle_inheritable`, :func:`os.set_handle_inheritable` |
| 727 | |
| 728 | |
R David Murray | 78d692f | 2013-10-10 17:23:26 -0400 | [diff] [blame] | 729 | pdb |
| 730 | --- |
| 731 | |
| 732 | The ``print`` command has been removed from :mod:`pdb`, restoring access to the |
| 733 | ``print`` function. |
| 734 | |
| 735 | Rationale: Python2's ``pdb`` did not have a ``print`` command; instead, |
| 736 | entering ``print`` executed the ``print`` statement. In Python3 ``print`` was |
| 737 | mistakenly made an alias for the pdb :pdbcmd:`p` command. ``p``, however, |
| 738 | prints the ``repr`` of its argument, not the ``str`` like the Python2 ``print`` |
| 739 | command did. Worse, the Python3 ``pdb print`` command shadowed the Python3 |
| 740 | ``print`` function, making it inaccessible at the ``pdb`` prompt. |
| 741 | |
| 742 | (Contributed by Connor Osborn in :issue:`18764`.) |
| 743 | |
| 744 | |
R David Murray | 809487e | 2013-12-22 20:49:40 -0500 | [diff] [blame] | 745 | .. _whatsnew-protocol-4: |
| 746 | |
| 747 | Pickle |
| 748 | ------ |
| 749 | |
| 750 | protocol 4 |
| 751 | |
| 752 | :mod:`pickle` now supports (but does not use by default) a new pickle protocol, |
| 753 | protocol 4. This new protocol addresses a number of issues that were present |
| 754 | in previous protocols, such as the serialization of nested classes, very large |
| 755 | strings and containers, or classes whose :meth:`__new__` method takes |
| 756 | keyword-only arguments. It also provides some efficiency improvements. |
| 757 | |
| 758 | .. seealso:: |
| 759 | |
| 760 | :pep:`3154` - Pickle protocol 4 |
| 761 | PEP written by Antoine Pitrou and implemented by Alexandre Vassalotti. |
| 762 | |
| 763 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 764 | poplib |
| 765 | ------ |
| 766 | |
| 767 | New :meth:`~poplib.POP3.stls` method to switch a clear-text POP3 session into |
| 768 | an encrypted POP3 session. |
| 769 | |
| 770 | New :meth:`~poplib.POP3.capa` method to query the capabilities advertised by the |
| 771 | POP3 server. |
| 772 | |
| 773 | (Contributed by Lorenzo Catucci in :issue:`4473`.) |
| 774 | |
| 775 | |
Serhiy Storchaka | 7c411a4 | 2013-10-02 11:56:18 +0300 | [diff] [blame] | 776 | pprint |
| 777 | ------ |
| 778 | |
Christian Heimes | e1bfd3e | 2013-10-21 12:32:21 +0200 | [diff] [blame] | 779 | The :mod:`pprint` module now supports *compact* mode for formatting long |
Serhiy Storchaka | 7c411a4 | 2013-10-02 11:56:18 +0300 | [diff] [blame] | 780 | sequences (:issue:`19132`). |
| 781 | |
| 782 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 783 | pydoc |
| 784 | ----- |
| 785 | |
| 786 | While significant changes have not been made to :mod:`pydoc` directly, |
| 787 | its handling of custom ``__dir__`` methods and various descriptor |
| 788 | behaviours has been improved substantially by the underlying changes in |
| 789 | the :mod:`inspect` module. |
| 790 | |
| 791 | |
Serhiy Storchaka | 32eddc1 | 2013-11-23 23:20:30 +0200 | [diff] [blame] | 792 | re |
| 793 | -- |
| 794 | |
| 795 | Added :func:`re.fullmatch` function and :meth:`regex.fullmatch` method, |
| 796 | which anchor the pattern at both ends of the string to match. |
| 797 | (Contributed by Matthew Barnett in :issue:`16203`.) |
| 798 | |
Ezio Melotti | dd7e291 | 2013-11-25 23:20:20 +0200 | [diff] [blame] | 799 | The repr of :ref:`regex objects <re-objects>` now includes the pattern |
| 800 | and the flags; the repr of :ref:`match objects <match-objects>` now |
| 801 | includes the start, end, and the part of the string that matched. |
Ezio Melotti | dd7e291 | 2013-11-25 23:20:20 +0200 | [diff] [blame] | 802 | (Contributed by Serhiy Storchaka in :issue:`13592` and :issue:`17087`.) |
| 803 | |
| 804 | |
Christian Heimes | b7bd5df | 2013-10-22 11:21:54 +0200 | [diff] [blame] | 805 | resource |
| 806 | -------- |
| 807 | |
| 808 | New :func:`resource.prlimit` function and Linux specific constants. |
| 809 | (Contributed by Christian Heimes in :issue:`16595` and :issue:`19324`.) |
| 810 | |
R David Murray | 8e37d5d | 2013-04-13 14:49:48 -0400 | [diff] [blame] | 811 | smtplib |
| 812 | ------- |
| 813 | |
R David Murray | 8a34596 | 2013-04-14 06:46:35 -0400 | [diff] [blame] | 814 | :exc:`~smtplib.SMTPException` is now a subclass of :exc:`OSError`, which allows |
R David Murray | 8e37d5d | 2013-04-13 14:49:48 -0400 | [diff] [blame] | 815 | both socket level errors and SMTP protocol level errors to be caught in one |
| 816 | try/except statement by code that only cares whether or not an error occurred. |
| 817 | (:issue:`2118`). |
| 818 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 819 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 820 | socket |
| 821 | ------ |
| 822 | |
Georg Brandl | 5642ff9 | 2013-09-15 10:37:57 +0200 | [diff] [blame] | 823 | Socket objects have new methods to get or set their :ref:`inheritable flag |
| 824 | <fd_inheritance>`: |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 825 | |
| 826 | * :meth:`socket.socket.get_inheritable`, :meth:`socket.socket.set_inheritable` |
| 827 | |
Eli Bendersky | 34567ec | 2013-08-31 15:18:48 -0700 | [diff] [blame] | 828 | The ``socket.AF_*`` and ``socket.SOCK_*`` constants are enumeration values, |
| 829 | using the new :mod:`enum` module. This allows descriptive reporting during |
| 830 | debugging, instead of seeing integer "magic numbers". |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 831 | |
Christian Heimes | 24cd4cf | 2013-06-22 19:31:58 +0200 | [diff] [blame] | 832 | ssl |
| 833 | --- |
| 834 | |
R David Murray | 748bad2 | 2013-12-20 17:08:39 -0500 | [diff] [blame] | 835 | .. _whatsnew-tls-11-12: |
Christian Heimes | 24cd4cf | 2013-06-22 19:31:58 +0200 | [diff] [blame] | 836 | |
R David Murray | 748bad2 | 2013-12-20 17:08:39 -0500 | [diff] [blame] | 837 | :data:`~ssl.PROTOCOL_TLSv1_1` and :data:`~ssl.PROTOCOL_TLSv1_2` (TLSv1.1 and |
| 838 | TLSv1.2 support) have been added; support for these protocols is only available if |
| 839 | Python is linked with OpenSSL 1.0.1 or later. (Contributed by Michele Orrù and |
| 840 | Antoine Pitrou in :issue:`16692`) |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 841 | |
R David Murray | 748bad2 | 2013-12-20 17:08:39 -0500 | [diff] [blame] | 842 | New diagnostic functions :func:`~ssl.get_default_verify_paths`, |
| 843 | :meth:`~ssl.SSLContext.cert_store_stats` and |
| 844 | :meth:`~ssl.SSLContext.get_ca_certs` (Contributed by Christian Heimes |
| 845 | in :issue:`18143` and :issue:`18147`) |
Christian Heimes | 24cd4cf | 2013-06-22 19:31:58 +0200 | [diff] [blame] | 846 | |
R David Murray | 748bad2 | 2013-12-20 17:08:39 -0500 | [diff] [blame] | 847 | Add :func:`ssl.enum_cert_store` to retrieve certificates and CRL from Windows' |
| 848 | cert store. (Contributed by Christian Heimes in :issue:`17134`.) |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 849 | |
| 850 | Support for server-side SNI using the new |
| 851 | :meth:`ssl.SSLContext.set_servername_callback` method. |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 852 | (Contributed by Daniel Black in :issue:`8109`.) |
| 853 | |
| 854 | |
Antoine Pitrou | d6cbd34 | 2013-08-12 20:48:15 +0200 | [diff] [blame] | 855 | stat |
| 856 | ---- |
| 857 | |
| 858 | The :mod:`stat` module is now backed by a C implementation in :mod:`_stat`. A C |
| 859 | implementation is required as most of the values aren't standardized and |
| 860 | platform-dependent. (Contributed by Christian Heimes in :issue:`11016`.) |
| 861 | |
| 862 | The module supports new file types: door, event port and whiteout. |
| 863 | |
| 864 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 865 | struct |
| 866 | ------ |
| 867 | |
| 868 | Streaming struct unpacking using :func:`struct.iter_unpack`. |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 869 | (Contributed by Antoine Pitrou in :issue:`17804`.) |
| 870 | |
| 871 | |
Serhiy Storchaka | e06a896 | 2013-09-04 00:43:03 +0300 | [diff] [blame] | 872 | sunau |
| 873 | ----- |
| 874 | |
| 875 | The :meth:`~sunau.getparams` method now returns a namedtuple rather than a |
| 876 | plain tuple. (Contributed by Claudiu Popa in :issue:`18901`.) |
| 877 | |
Serhiy Storchaka | 34d2013 | 2013-09-05 17:01:53 +0300 | [diff] [blame] | 878 | :meth:`sunau.open` now supports the context manager protocol (:issue:`18878`). |
| 879 | |
Serhiy Storchaka | e06a896 | 2013-09-04 00:43:03 +0300 | [diff] [blame] | 880 | |
Andrew Kuchling | 173a157 | 2013-09-15 18:15:56 -0400 | [diff] [blame] | 881 | traceback |
| 882 | --------- |
| 883 | |
| 884 | A new :func:`traceback.clear_frames` function takes a traceback object |
| 885 | and clears the local variables in all of the frames it references, |
| 886 | reducing the amount of memory consumed (:issue:`1565525`). |
| 887 | |
| 888 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 889 | urllib |
| 890 | ------ |
| 891 | |
| 892 | Add support.for ``data:`` URLs in :mod:`urllib.request`. |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 893 | (Contributed by Mathias Panzenböck in :issue:`16423`.) |
| 894 | |
| 895 | |
| 896 | unittest |
| 897 | -------- |
| 898 | |
| 899 | Support for easy dynamically-generated subtests using the |
| 900 | :meth:`~unittest.TestCase.subTest` context manager. |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 901 | (Contributed by Antoine Pitrou in :issue:`16997`.) |
| 902 | |
R David Murray | 8e37d5d | 2013-04-13 14:49:48 -0400 | [diff] [blame] | 903 | |
R David Murray | 671cd32 | 2013-04-10 12:31:43 -0400 | [diff] [blame] | 904 | wave |
| 905 | ---- |
| 906 | |
| 907 | The :meth:`~wave.getparams` method now returns a namedtuple rather than a |
| 908 | plain tuple. (Contributed by Claudiu Popa in :issue:`17487`.) |
| 909 | |
R David Murray | c91d5ee | 2013-07-31 13:46:08 -0400 | [diff] [blame] | 910 | :meth:`wave.open` now supports the context manager protocol. (Contributed |
| 911 | by Claudiu Popa in :issue:`17616`.) |
| 912 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 913 | |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 914 | weakref |
| 915 | ------- |
| 916 | |
| 917 | New :class:`~weakref.WeakMethod` class simulates weak references to bound |
Nick Coghlan | be57ab8 | 2013-09-22 21:26:30 +1000 | [diff] [blame] | 918 | methods. (Contributed by Antoine Pitrou in :issue:`14631`.) |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 919 | |
Nick Coghlan | be57ab8 | 2013-09-22 21:26:30 +1000 | [diff] [blame] | 920 | New :class:`~weakref.finalize` class makes it possible to register a callback |
| 921 | to be invoked when an object is garbage collected, without needing to |
| 922 | carefully manage the lifecycle of the weak reference itself. (Contributed by |
| 923 | Richard Oudkerk in :issue:`15528`) |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 924 | |
| 925 | |
| 926 | xml.etree |
| 927 | --------- |
| 928 | |
| 929 | Add an event-driven parser for non-blocking applications, |
Eli Bendersky | b586934 | 2013-08-30 05:51:20 -0700 | [diff] [blame] | 930 | :class:`~xml.etree.ElementTree.XMLPullParser`. |
Eli Bendersky | b586934 | 2013-08-30 05:51:20 -0700 | [diff] [blame] | 931 | (Contributed by Antoine Pitrou in :issue:`17741`.) |
Antoine Pitrou | f89aa9a | 2013-08-12 20:46:47 +0200 | [diff] [blame] | 932 | |
Christian Tismer | 59202e5 | 2013-10-21 03:59:23 +0200 | [diff] [blame] | 933 | |
| 934 | zipfile.PyZipfile |
| 935 | ----------------- |
| 936 | |
| 937 | Add a filter function to ignore some packages (tests for instance), |
| 938 | :meth:`~zipfile.PyZipFile.writepy`. |
Christian Tismer | 59202e5 | 2013-10-21 03:59:23 +0200 | [diff] [blame] | 939 | (Contributed by Christian Tismer in :issue:`19274`.) |
| 940 | |
| 941 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 942 | CPython Implementation Changes |
| 943 | ============================== |
| 944 | |
| 945 | |
R David Murray | c16dfe1 | 2013-12-21 12:32:10 -0500 | [diff] [blame] | 946 | .. _whatsnew-pep-445: |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 947 | |
| 948 | PEP 445: Customization of CPython memory allocators |
| 949 | --------------------------------------------------- |
| 950 | |
| 951 | :pep:`445` adds new C level interfaces to customize memory allocation in |
| 952 | the CPython interpreter. |
| 953 | |
| 954 | .. seealso:: |
| 955 | |
| 956 | :pep:`445` - Add new APIs to customize Python memory allocators |
| 957 | PEP written and implemented by Victor Stinner. |
| 958 | |
| 959 | |
R David Murray | c16dfe1 | 2013-12-21 12:32:10 -0500 | [diff] [blame] | 960 | .. _whatsnew-pep-442: |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 961 | |
| 962 | PEP 442: Safe object finalization |
| 963 | --------------------------------- |
| 964 | |
| 965 | :pep:`442` removes the current limitations and quirks of object finalization |
| 966 | in CPython. With it, objects with :meth:`__del__` methods, as well as |
| 967 | generators with :keyword:`finally` clauses, can be finalized when they are |
| 968 | part of a reference cycle. |
| 969 | |
| 970 | As part of this change, module globals are no longer forcibly set to |
| 971 | :const:`None` during interpreter shutdown in most cases, instead relying |
R David Murray | ca79461 | 2013-12-22 14:05:11 -0500 | [diff] [blame] | 972 | on the normal operation of the cyclic garbage collector. This avoids a |
| 973 | whole class of interpreter-shutdown-time errors, usually involving |
| 974 | ``__del__`` methods, that have plagued Python since the cyclic GC |
| 975 | was first introduced. |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 976 | |
| 977 | .. seealso:: |
| 978 | |
| 979 | :pep:`442` - Safe object finalization |
| 980 | PEP written and implemented by Antoine Pitrou. |
| 981 | |
| 982 | |
R David Murray | c16dfe1 | 2013-12-21 12:32:10 -0500 | [diff] [blame] | 983 | .. _whatsnew-pep-456: |
| 984 | |
| 985 | PEP 456: Secure and Interchangeable Hash Algorithm |
| 986 | -------------------------------------------------- |
| 987 | |
| 988 | :pep:`456` follows up on earlier security fix work done on Python's hash |
| 989 | algorithm to address certain DOS attacks to which public facing APIs backed by |
| 990 | dictionary lookups may be subject. (See :issue:`14621` for the start of the |
| 991 | current round of improvements.) The PEP unifies CPython's hash code to make it |
| 992 | easier for a packager to substitute a different hash algorithm, and switches |
| 993 | Python's default implementation to a SipHash implementation on platforms that |
| 994 | have a 64 bit data type. Any performance differences in comparison with the |
| 995 | older FNV algorithm are trivial. |
| 996 | |
| 997 | The PEP adds additional fields to the :func:`sys.hash_info` struct sequence to |
| 998 | describe the hash algorithm in use by the currently executing binary. Otherwise, |
| 999 | the PEP does not alter any existing CPython APIs. |
| 1000 | |
| 1001 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 1002 | Other build and C API changes |
| 1003 | ----------------------------- |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1004 | |
| 1005 | Changes to Python's build process and to the C API include: |
| 1006 | |
Nick Coghlan | 7d270ee | 2013-10-17 22:35:35 +1000 | [diff] [blame] | 1007 | * The new :c:func:`Py_SetStandardStreamEncoding` pre-initialization API |
| 1008 | allows applications embedding the CPython interpreter to reliably force |
| 1009 | a particular encoding and error handler for the standard streams |
| 1010 | (Contributed by Bastien Montagne and Nick Coghlan in :issue:`16129`) |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1011 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 1012 | * Most Python C APIs that don't mutate string arguments are now correctly |
| 1013 | marked as accepting ``const char *`` rather than ``char *`` (Contributed |
| 1014 | by Serhiy Storchaka in :issue:`1772673`). |
| 1015 | |
R David Murray | 2aa9d52 | 2013-12-22 13:57:45 -0500 | [diff] [blame] | 1016 | .. _whatsnew-pep-436: |
| 1017 | |
Nick Coghlan | 0acceb7 | 2013-10-20 13:22:21 +1000 | [diff] [blame] | 1018 | * "Argument Clinic" (:pep:`436`) is now part of the CPython build process |
| 1019 | and can be used to simplify the process of defining and maintaining |
| 1020 | accurate signatures for builtins and standard library extension modules |
| 1021 | implemented in C. |
| 1022 | |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 1023 | .. note:: |
| 1024 | The Argument Clinic PEP is not fully up to date with the state of the |
| 1025 | implementation. This has been deemed acceptable by the release manager |
| 1026 | and core development team in this case, as Argument Clinic will not |
| 1027 | be made available as a public API for third party use in Python 3.4. |
| 1028 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1029 | |
R David Murray | bcaaecf | 2013-12-23 21:23:36 -0500 | [diff] [blame] | 1030 | Other improvements |
| 1031 | ================== |
| 1032 | |
| 1033 | * Tab-completion is now enabled by default in the interactive interpreter. |
| 1034 | (Contributed by Antoine Pitrou and Éric Araujo in :issue:`5845`.) |
| 1035 | |
| 1036 | * Invoking the Python interpreter with ``--version`` now outputs the version to |
| 1037 | standard output instead of standard error (:issue:`18338`). Similar changes |
| 1038 | were made to :mod:`argparse` (:issue:`18920`) and other modules that have |
| 1039 | script-like invocation capabilities (:issue:`18922`). |
| 1040 | |
R David Murray | 72420ff | 2013-12-24 10:46:44 -0500 | [diff] [blame^] | 1041 | * The CPython Windows installer now adds ``.py`` to the :envvar:`PATHEXT` |
| 1042 | variable when extensions are registered, allowing users to run a python |
| 1043 | script at the windows command prompt by just typing its name without the |
| 1044 | ``.py`` extension. (Contributed by Paul Moore in :issue:`18569`.) |
| 1045 | |
R David Murray | bcaaecf | 2013-12-23 21:23:36 -0500 | [diff] [blame] | 1046 | |
| 1047 | Optimizations |
| 1048 | ============= |
| 1049 | |
| 1050 | Major performance enhancements have been added: |
| 1051 | |
| 1052 | * The UTF-32 decoder is now 3x to 4x faster. |
| 1053 | |
| 1054 | * The cost of hash collisions for sets is now reduced. Each hash table |
| 1055 | probe now checks a series of consecutive, adjacent key/hash pairs before |
| 1056 | continuing to make random probes through the hash table. This exploits |
| 1057 | cache locality to make collision resolution less expensive. |
| 1058 | |
| 1059 | The collision resolution scheme can be described as a hybrid of linear |
| 1060 | probing and open addressing. The number of additional linear probes |
| 1061 | defaults to nine. This can be changed at compile-time by defining |
| 1062 | LINEAR_PROBES to be any value. Set LINEAR_PROBES=0 to turn-off |
| 1063 | linear probing entirely. |
| 1064 | |
| 1065 | (Contributed by Raymond Hettinger in :issue:`18771`.) |
| 1066 | |
| 1067 | * The interpreter starts about 30% faster. A couple of measures lead to the |
| 1068 | speedup. The interpreter loads fewer modules on startup, e.g. the :mod:`re`, |
| 1069 | :mod:`collections` and :mod:`locale` modules and their dependencies are no |
| 1070 | longer imported by default. The marshal module has been improved to load |
| 1071 | compiled Python code faster. |
| 1072 | |
| 1073 | (Contributed by Antoine Pitrou, Christian Heimes and Victor Stinner in |
| 1074 | :issue:`19219`, :issue:`19218`, :issue:`19209`, :issue:`19205` and |
| 1075 | :issue:`9548`) |
| 1076 | |
| 1077 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1078 | Deprecated |
| 1079 | ========== |
| 1080 | |
| 1081 | Unsupported Operating Systems |
| 1082 | ----------------------------- |
| 1083 | |
Victor Stinner | f3fd13b | 2013-08-04 10:30:57 +0200 | [diff] [blame] | 1084 | * OS/2 |
Victor Stinner | f3fd13b | 2013-08-04 10:30:57 +0200 | [diff] [blame] | 1085 | * Windows 2000 |
Christian Heimes | af01f66 | 2013-12-21 16:19:10 +0100 | [diff] [blame] | 1086 | * VMS |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1087 | |
| 1088 | |
| 1089 | Deprecated Python modules, functions and methods |
| 1090 | ------------------------------------------------ |
| 1091 | |
Terry Jan Reedy | 2b6c26e | 2013-03-21 19:36:26 -0400 | [diff] [blame] | 1092 | * :meth:`difflib.SequenceMatcher.isbjunk` and |
Andrew Kuchling | 0d0813a | 2013-06-15 13:29:09 -0400 | [diff] [blame] | 1093 | :meth:`difflib.SequenceMatcher.isbpopular` were removed: use ``x in sm.bjunk`` and |
| 1094 | ``x in sm.bpopular``, where *sm* is a :class:`~difflib.SequenceMatcher` object. |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1095 | |
Brett Cannon | 82b3d6a | 2013-06-14 22:37:11 -0400 | [diff] [blame] | 1096 | * :func:`importlib.util.module_for_loader` is pending deprecation. Using |
| 1097 | :func:`importlib.util.module_to_load` and |
| 1098 | :meth:`importlib.abc.Loader.init_module_attrs` allows subclasses of a loader |
| 1099 | to more easily customize module loading. |
| 1100 | |
Brett Cannon | e4f41de | 2013-06-16 13:13:40 -0400 | [diff] [blame] | 1101 | * The :mod:`imp` module is pending deprecation. To keep compatibility with |
| 1102 | Python 2/3 code bases, the module's removal is currently not scheduled. |
| 1103 | |
Brett Cannon | 1448ecf | 2013-10-04 11:38:59 -0400 | [diff] [blame] | 1104 | * The :mod:`formatter` module is pending deprecation and is slated for removal |
| 1105 | in Python 3.6. |
| 1106 | |
Christian Heimes | 634919a | 2013-11-20 17:23:06 +0100 | [diff] [blame] | 1107 | * MD5 as default digestmod for :mod:`hmac` is deprecated. Python 3.6 will |
| 1108 | require an explicit digest name or constructor as *digestmod* argument. |
| 1109 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1110 | |
| 1111 | Deprecated functions and types of the C API |
| 1112 | ------------------------------------------- |
| 1113 | |
Victor Stinner | 3dd263f | 2013-10-23 18:54:43 +0200 | [diff] [blame] | 1114 | * The ``PyThreadState.tick_counter`` field has been removed: its value was |
| 1115 | meaningless since Python 3.2 ("new GIL"). |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1116 | |
| 1117 | |
| 1118 | Deprecated features |
| 1119 | ------------------- |
| 1120 | |
Antoine Pitrou | 3b2f0f0 | 2013-10-25 21:39:26 +0200 | [diff] [blame] | 1121 | * The site module adding a "site-python" directory to sys.path, if it |
| 1122 | exists, is deprecated (:issue:`19375`). |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1123 | |
| 1124 | |
R David Murray | 72420ff | 2013-12-24 10:46:44 -0500 | [diff] [blame^] | 1125 | Removed |
| 1126 | ======= |
| 1127 | |
| 1128 | * The unmaintained ``Misc/TextMate`` and ``Misc/vim`` directories have been |
| 1129 | removed (see the devguide__ for what to use instead). |
| 1130 | |
| 1131 | __ http://docs.python.org/devguide |
| 1132 | |
| 1133 | |
Benjamin Peterson | 88f3b23 | 2012-10-04 12:45:10 -0400 | [diff] [blame] | 1134 | Porting to Python 3.4 |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1135 | ===================== |
| 1136 | |
Victor Stinner | 774b2e0 | 2013-12-13 14:33:01 +0100 | [diff] [blame] | 1137 | Changes in the Python API |
| 1138 | ------------------------- |
| 1139 | |
Georg Brandl | b80f511 | 2012-09-30 09:11:58 +0200 | [diff] [blame] | 1140 | This section lists previously described changes and other bugfixes |
| 1141 | that may require changes to your code. |
| 1142 | |
Brett Cannon | 777622b | 2013-04-09 17:03:10 -0400 | [diff] [blame] | 1143 | * The ABCs defined in :mod:`importlib.abc` now either raise the appropriate |
| 1144 | exception or return a default value instead of raising |
| 1145 | :exc:`NotImplementedError` blindly. This will only affect code calling |
| 1146 | :func:`super` and falling through all the way to the ABCs. For compatibility, |
| 1147 | catch both :exc:`NotImplementedError` or the appropriate exception as needed. |
Brett Cannon | 4c14b5d | 2013-05-04 13:56:58 -0400 | [diff] [blame] | 1148 | |
| 1149 | * The module type now initializes the :attr:`__package__` and :attr:`__loader__` |
| 1150 | attributes to ``None`` by default. To determine if these attributes were set |
| 1151 | in a backwards-compatible fashion, use e.g. |
Brett Cannon | 3dc48d6 | 2013-05-28 18:35:54 -0400 | [diff] [blame] | 1152 | ``getattr(module, '__loader__', None) is not None``. |
| 1153 | |
| 1154 | * :meth:`importlib.util.module_for_loader` now sets ``__loader__`` and |
| 1155 | ``__package__`` unconditionally to properly support reloading. If this is not |
| 1156 | desired then you will need to set these attributes manually. You can use |
Brett Cannon | 028d512 | 2013-05-31 18:02:11 -0400 | [diff] [blame] | 1157 | :func:`importlib.util.module_to_load` for module management. |
Brett Cannon | 3e0651b | 2013-05-31 23:18:39 -0400 | [diff] [blame] | 1158 | |
| 1159 | * Import now resets relevant attributes (e.g. ``__name__``, ``__loader__``, |
| 1160 | ``__package__``, ``__file__``, ``__cached__``) unconditionally when reloading. |
| 1161 | |
Brett Cannon | 1448ecf | 2013-10-04 11:38:59 -0400 | [diff] [blame] | 1162 | * Frozen packages no longer set ``__path__`` to a list containing the package |
| 1163 | name but an empty list instead. Determing if a module is a package should be |
| 1164 | done using ``hasattr(module, '__path__')``. |
Brett Cannon | 8f5ac51 | 2013-06-12 23:29:18 -0400 | [diff] [blame] | 1165 | |
Brett Cannon | 33915eb | 2013-06-14 18:33:00 -0400 | [diff] [blame] | 1166 | * :func:`py_compile.compile` now raises :exc:`FileExistsError` if the file path |
| 1167 | it would write to is a symlink or a non-regular file. This is to act as a |
| 1168 | warning that import will overwrite those files with a regular file regardless |
| 1169 | of what type of file path they were originally. |
Brett Cannon | f4375ef | 2013-06-16 18:05:54 -0400 | [diff] [blame] | 1170 | |
| 1171 | * :meth:`importlib.abc.SourceLoader.get_source` no longer raises |
| 1172 | :exc:`ImportError` when the source code being loaded triggers a |
| 1173 | :exc:`SyntaxError` or :exc:`UnicodeDecodeError`. As :exc:`ImportError` is |
| 1174 | meant to be raised only when source code cannot be found but it should, it was |
| 1175 | felt to be over-reaching/overloading of that meaning when the source code is |
| 1176 | found but improperly structured. If you were catching ImportError before and |
| 1177 | wish to continue to ignore syntax or decoding issues, catch all three |
Victor Stinner | 84e33c8 | 2013-06-21 00:31:55 +0200 | [diff] [blame] | 1178 | exceptions now. |
Nick Coghlan | 24c05bc | 2013-07-15 21:13:08 +1000 | [diff] [blame] | 1179 | |
| 1180 | * :func:`functools.update_wrapper` and :func:`functools.wraps` now correctly |
Nick Coghlan | 367df12 | 2013-10-27 01:57:34 +1000 | [diff] [blame] | 1181 | set the ``__wrapped__`` attribute to the function being wrapper, even if |
| 1182 | that function also had its ``__wrapped__`` attribute set. This means |
| 1183 | ``__wrapped__`` attributes now correctly link a stack of decorated |
| 1184 | functions rather than every ``__wrapped__`` attribute in the chain |
| 1185 | referring to the innermost function. Introspection libraries that |
| 1186 | assumed the previous behaviour was intentional can use |
| 1187 | :func:`inspect.unwrap` to access the first function in the chain that has |
| 1188 | no ``__wrapped__`` attribute. |
Victor Stinner | 2fe9bac | 2013-10-10 16:18:20 +0200 | [diff] [blame] | 1189 | |
Georg Brandl | 0f5bff2 | 2013-10-19 17:46:38 +0200 | [diff] [blame] | 1190 | * :class:`importlib.machinery.PathFinder` now passes on the current working |
Brett Cannon | 27e27f7 | 2013-10-18 11:39:04 -0400 | [diff] [blame] | 1191 | directory to objects in :data:`sys.path_hooks` for the empty string. This |
| 1192 | results in :data:`sys.path_importer_cache` never containing ``''``, thus |
| 1193 | iterating through :data:`sys.path_importer_cache` based on :data:`sys.path` |
| 1194 | will not find all keys. A module's ``__file__`` when imported in the current |
| 1195 | working directory will also now have an absolute path, including when using |
| 1196 | ``-m`` with the interpreter (this does not influence when the path to a file |
| 1197 | is specified on the command-line). |
Victor Stinner | 2748bc7 | 2013-12-13 10:57:04 +0100 | [diff] [blame] | 1198 | |
Victor Stinner | 774b2e0 | 2013-12-13 14:33:01 +0100 | [diff] [blame] | 1199 | Changes in the C API |
| 1200 | -------------------- |
| 1201 | |
| 1202 | * :c:func:`PyErr_SetImportError` now sets :exc:`TypeError` when its **msg** |
| 1203 | argument is not set. Previously only ``NULL`` was returned with no exception |
| 1204 | set. |
| 1205 | |
| 1206 | * The result of the :c:data:`PyOS_ReadlineFunctionPointer` callback must |
| 1207 | now be a string allocated by :c:func:`PyMem_RawMalloc` or |
| 1208 | :c:func:`PyMem_RawRealloc`, or *NULL* if an error occurred, instead of a |
| 1209 | string allocated by :c:func:`PyMem_Malloc` or :c:func:`PyMem_Realloc`. |
| 1210 | |
| 1211 | * :c:func:`PyThread_set_key_value` now always set the value. In Python |
Victor Stinner | 2748bc7 | 2013-12-13 10:57:04 +0100 | [diff] [blame] | 1212 | 3.3, the function did nothing if the key already exists (if the current |
| 1213 | value is a non-NULL pointer). |
| 1214 | |
Victor Stinner | 774b2e0 | 2013-12-13 14:33:01 +0100 | [diff] [blame] | 1215 | * The ``f_tstate`` (thread state) field of the :c:type:`PyFrameObject` |
| 1216 | structure has been removed to fix a bug: see :issue:`14432` for the |
| 1217 | rationale. |
| 1218 | |