Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1 | **************************** |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 2 | What's New In Python 3.2 |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 3 | **************************** |
| 4 | |
| 5 | :Author: Raymond Hettinger |
| 6 | :Release: |release| |
| 7 | :Date: |today| |
| 8 | |
| 9 | .. $Id$ |
| 10 | Rules for maintenance: |
| 11 | |
| 12 | * Anyone can add text to this document. Do not spend very much time |
| 13 | on the wording of your changes, because your text will probably |
| 14 | get rewritten to some degree. |
| 15 | |
| 16 | * The maintainer will go through Misc/NEWS periodically and add |
| 17 | changes; it's therefore more important to add your changes to |
| 18 | Misc/NEWS than to this file. |
| 19 | |
| 20 | * This is not a complete list of every single change; completeness |
| 21 | is the purpose of Misc/NEWS. Some changes I consider too small |
| 22 | or esoteric to include. If such a change is added to the text, |
| 23 | I'll just remove it. (This is another reason you shouldn't spend |
| 24 | too much time on writing your addition.) |
| 25 | |
| 26 | * If you want to draw your new text to the attention of the |
| 27 | maintainer, add 'XXX' to the beginning of the paragraph or |
| 28 | section. |
| 29 | |
| 30 | * It's OK to just add a fragmentary note about a change. For |
| 31 | example: "XXX Describe the transmogrify() function added to the |
| 32 | socket module." The maintainer will research the change and |
| 33 | write the necessary text. |
| 34 | |
| 35 | * You can comment out your additions if you like, but it's not |
| 36 | necessary (especially when a final release is some months away). |
| 37 | |
| 38 | * Credit the author of a patch or bugfix. Just the name is |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 39 | sufficient; the e-mail address isn't necessary. It's helpful to |
| 40 | add the issue number: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 41 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 42 | XXX Describe the transmogrify() function added to the socket |
| 43 | module. |
| 44 | |
| 45 | (Contributed by P.Y. Developer; :issue:`12345`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 46 | |
| 47 | This saves the maintainer the effort of going through the SVN log |
| 48 | when researching a change. |
| 49 | |
| 50 | This article explains the new features in Python 3.2, compared to 3.1. |
| 51 | |
| 52 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 53 | PEP 391: Dictionary Based Configuration for Logging |
| 54 | ==================================================== |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 55 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 56 | The :mod:`logging` module provided two kinds of configuration, one style with |
| 57 | function calls for each option or another style driven by an external file saved |
| 58 | in a :mod:`ConfigParser` format. Those options did not provide the flexibility |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame^] | 59 | to create configurations from JSON or YAML files, nor did they not support |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 60 | incremental configuration, which is needed for specifying logger options from a |
| 61 | command line. |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 62 | |
| 63 | To support a more flexible style, the module now offers |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 64 | :func:`logging.config.dictConfig` for specifying logging configuration with |
| 65 | plain Python dictionaries. The configuration options include formatters, |
| 66 | handlers, filters, and loggers. Here's a working example of a configuration |
| 67 | dictionary:: |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 68 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 69 | {"version": 1, |
| 70 | "formatters": {"brief": {"format": "%(levelname)-8s: %(name)-15s: %(message)s"}, |
| 71 | "full": {"format": "%(asctime)s %(name)-15s %(levelname)-8s %(message)s"}, |
| 72 | }, |
| 73 | "handlers": {"console": { |
| 74 | "class": "logging.StreamHandler", |
| 75 | "formatter": "brief", |
| 76 | "level": "INFO", |
| 77 | "stream": "ext://sys.stdout"}, |
| 78 | "console_priority": { |
| 79 | "class": "logging.StreamHandler", |
| 80 | "formatter": "full", |
| 81 | "level": "ERROR", |
| 82 | "stream": "ext://sys.stderr"}, |
| 83 | }, |
| 84 | "root": {"level": "DEBUG", "handlers": ["console", "console_priority"]}} |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 85 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 86 | |
| 87 | If that dictionary is stored in a file called "conf.json", it can loaded |
| 88 | and called with code like this:: |
| 89 | |
| 90 | >>> import logging.config |
| 91 | >>> logging.config.dictConfig(json.load(open('conf.json', 'rb'))) |
| 92 | >>> logging.info("Transaction completed normally") |
| 93 | >>> logging.critical("Abnormal termination") |
| 94 | |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 95 | .. seealso:: |
| 96 | |
| 97 | :pep:`391` - Dictionary Based Configuration for Logging |
| 98 | PEP written by Vinay Sajip. |
| 99 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 100 | |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 101 | PEP 3147: PYC Repository Directories |
| 102 | ===================================== |
| 103 | |
| 104 | Python's scheme for caching bytecode in *.pyc* files did not work well in |
| 105 | environments with multiple python interpreters. If one interpreter encountered |
| 106 | a cached file created by another interpreter, it would recompile the source and |
| 107 | overwrite the cached file, thus losing the benefits of caching. |
| 108 | |
| 109 | The issue of "pyc fights" has become more pronounced as it has become |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 110 | commonplace for Linux distributions to ship with multiple versions of Python. |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 111 | These conflicts also arise with CPython alternatives such as Unladen Swallow. |
| 112 | |
| 113 | To solve this problem, Python's import machinery has been extended to use |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 114 | distinct filenames for each interpreter. Instead of Python 3.2 and Python 3.3 and |
| 115 | Unladen Swallow each competing for a file called "mymodule.pyc", they will now |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 116 | look for "mymodule.cpython-32.pyc", "mymodule.cpython-33.pyc", and |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 117 | "mymodule.unladen10.pyc". And to prevent all of these new files from |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 118 | cluttering source directories, the *pyc* files are now collected in a |
| 119 | "__pycache__" directory stored under the package directory. |
| 120 | |
| 121 | Aside from the filenames and target directories, the new scheme has a few |
| 122 | aspects that are visible to the programmer: |
| 123 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 124 | * Imported modules now have a :attr:`__cached__` attribute which stores the name |
| 125 | of the actual file that was imported: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 126 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 127 | >>> import collections |
| 128 | >>> collections.__cached__ |
| 129 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 130 | |
| 131 | * The tag that is unique to each interpreter is accessible from the :mod:`imp` |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 132 | module: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 133 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 134 | >>> import imp |
| 135 | >>> imp.get_tag() |
| 136 | 'cpython-32' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 137 | |
| 138 | * Scripts that try to deduce source filename from the imported file now need to |
| 139 | be smarter. It is no longer sufficient to simply strip the "c" from a ".pyc" |
| 140 | filename. Instead, use the new functions in the :mod:`imp` module: |
| 141 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 142 | >>> imp.source_from_cache('c:/py32/lib/__pycache__/collections.cpython-32.pyc') |
| 143 | 'c:/py32/lib/collections.py' |
| 144 | >>> imp.cache_from_source('c:/py32/lib/collections.py') |
| 145 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 146 | |
| 147 | * The :mod:`py_compile` and :mod:`compileall` modules have been updated to |
| 148 | reflect the new naming convention and target directory. |
| 149 | |
| 150 | .. seealso:: |
| 151 | |
| 152 | :pep:`3147` - PYC Repository Directories |
| 153 | PEP written by Barry Warsaw. |
| 154 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 155 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 156 | PEP 3149 ABI Version Tagged .so Files |
| 157 | ===================================== |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 158 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 159 | The PYC repository directory allows multiple bytecode cache files to be |
| 160 | co-located. This PEP implements a similar mechanism for shared object files by |
| 161 | giving them a common directory and distinct names for each version. |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 162 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 163 | The common directory is "pyshared" and the file names are made distinct by |
| 164 | identifying the Python implementation (such as CPython, PyPy, Jython, etc.), the |
| 165 | major and minor version numbers, and optional build flags (such as "d" for |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 166 | debug, "m" for pymalloc, "u" for wide-unicode). For an arbitrary package "foo", |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 167 | you may see these files when the distribution package is installed:: |
| 168 | |
| 169 | /usr/share/pyshared/foo.cpython-32m.so |
| 170 | /usr/share/pyshared/foo.cpython-33md.so |
| 171 | |
| 172 | In Python itself, the tags are accessible from functions in the :mod:`sysconfig` |
| 173 | module:: |
| 174 | |
| 175 | >>> import sysconfig |
| 176 | >>> sysconfig.get_config_var('SOABI') # find the version tag |
| 177 | 'cpython-32mu' |
| 178 | >>> sysconfig.get_config_var('SO') # find the full filename extension |
| 179 | 'cpython-32mu.so' |
| 180 | |
| 181 | .. seealso:: |
| 182 | |
| 183 | :pep:`3149` - ABI Version Tagged .so Files |
| 184 | PEP written by Barry Warsaw. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 185 | |
| 186 | |
| 187 | Other Language Changes |
| 188 | ====================== |
| 189 | |
| 190 | Some smaller changes made to the core Python language are: |
| 191 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 192 | * The :func:`hasattr` function used to catch and suppress any Exception. Now, |
| 193 | it only catches :exc:`AttributeError`. Under the hood, :func:`hasattr` works |
| 194 | by calling :func:`getattr` and throwing away the results. This is necessary |
| 195 | because dynamic attribute creation is possible using :meth:`__getattribute__` |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 196 | or :meth:`__getattr__`. If :func:`hasattr` were to just scan instance and class |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 197 | dictionaries it would miss the dynmaic methods and make it difficult to |
| 198 | implement proxy objects. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 199 | |
| 200 | (Discovered by Yury Selivanov and fixed by Benjamin Peterson; :issue:`9666`.) |
| 201 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 202 | * The :func:`str` of a float or complex number is now the same as its |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 203 | :func:`repr`. Previously, the :func:`str` form was shorter but that just |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 204 | caused confusion and is no longer needed now that the shortest possible |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 205 | :func:`repr` is displayed by default: |
Raymond Hettinger | bb734c6 | 2010-09-05 05:56:44 +0000 | [diff] [blame] | 206 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 207 | >>> repr(math.pi) |
| 208 | '3.141592653589793' |
| 209 | >>> str(math.pi) |
| 210 | '3.141592653589793' |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 211 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 212 | (Proposed and implemented by Mark Dickinson; :issue:`9337`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 213 | |
Raymond Hettinger | 6e8fe97 | 2010-09-05 06:13:47 +0000 | [diff] [blame] | 214 | * The :func:`functools.wraps` decorator now adds a :attr:`__wrapped__` attribute |
| 215 | pointing to the original callable function. This allows wrapped functions to |
| 216 | be introspected. It also copies :attr:`__annotations__` if defined. And now |
| 217 | it also gracefully skips over missing attributes such as :attr:`__doc__` which |
| 218 | might not be defined for the wrapped callable. |
| 219 | |
| 220 | (By Nick Coghlan and Terrence Cole; :issue:`9567`, :issue:`3445`, and |
| 221 | :issue:`8814`.) |
| 222 | |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame^] | 223 | * The :mod:`abc` module now supports :func:`abstractclassmethod` and |
| 224 | :func:`abstractstaticmethod`. |
Raymond Hettinger | 6e8fe97 | 2010-09-05 06:13:47 +0000 | [diff] [blame] | 225 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 226 | (Patch submitted by Daniel Urban; :issue:`5867`.) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 227 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 228 | * A warning message will now get printed at interpreter shutdown if the |
| 229 | :data:`gc.garbage` list isn't empty. This is meant to make the programmer |
| 230 | aware that their code contains object finalization issues. |
| 231 | |
| 232 | (Added by Antoine Pitrou; :issue:`477863`.) |
| 233 | |
| 234 | * Mark Dickinson crafted an elegant and efficient scheme for assuring that |
| 235 | different numeric datatypes will have the same hash value whenever their |
| 236 | actual values are equal:: |
| 237 | |
| 238 | >>> assert hash(Fraction(3, 2)) == hash(1.5) == \ |
| 239 | hash(Decimal("1.5")) == hash(complex(1.5, 0)) |
| 240 | |
| 241 | (See :issue:`8188`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 242 | |
| 243 | New, Improved, and Deprecated Modules |
| 244 | ===================================== |
| 245 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 246 | * The :mod:`functools` module includes a new decorator for caching function |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 247 | calls. :func:`functools.lru_cache` can save repeated queries to an external |
| 248 | resource whenever the results are expected to be the same. |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 249 | |
Raymond Hettinger | 86f9613 | 2010-08-06 23:23:49 +0000 | [diff] [blame] | 250 | For example, adding a caching decorator to a database query function can save |
| 251 | database accesses for popular searches:: |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 252 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 253 | @functools.lru_cache(maxsize=300) |
| 254 | def get_phone_number(name): |
| 255 | c = conn.cursor() |
| 256 | c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,)) |
| 257 | return c.fetchone()[0] |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 258 | |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 259 | To help with choosing an effective cache size, the wrapped function is |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 260 | instrumented with two attributes *cache_hits* and *cache_misses*: |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 261 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 262 | >>> for name in user_requests: |
| 263 | ... get_phone_number(name) |
| 264 | >>> print(get_phone_number.cache_hits, get_phone_number.cache_misses) |
| 265 | 4805 980 |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 266 | |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 267 | If the phonelist table gets updated, the outdated contents of the cache can be |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 268 | cleared with: |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 269 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 270 | >>> get_phone_number.cache_clear() |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 271 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 272 | (Contributed by Raymond Hettinger.) |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 273 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 274 | * The previously deprecated :func:`contextlib.nested` function has been removed |
| 275 | in favor of a plain :keyword:`with` statement which can accept multiple |
| 276 | context managers. The latter technique is faster (because it is built-in), |
| 277 | and it does a better job finalizing multiple context managers when one of them |
| 278 | raises an exception. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 279 | |
| 280 | (Contributed by Georg Brandl and Mattias Brändström; |
| 281 | `appspot issue 53094 <http://codereview.appspot.com/53094>`_.) |
| 282 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 283 | * The :class:`ftplib.FTP` class now supports the context manager protocol to |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 284 | unconditionally consume :exc:`socket.error` exceptions and to close the FTP |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 285 | connection when done:: |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 286 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 287 | >>> from ftplib import FTP |
| 288 | >>> with FTP("ftp1.at.proftpd.org") as ftp: |
| 289 | ... ftp.login() |
| 290 | ... ftp.dir() |
| 291 | ... |
| 292 | '230 Anonymous login ok, restrictions apply.' |
| 293 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 . |
| 294 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .. |
| 295 | dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS |
| 296 | dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 297 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 298 | Other file-like objects such as :class:`mmap.mmap` and :func:`fileinput.input` |
| 299 | also grew auto-closing context managers:: |
Giampaolo Rodolà | bd576b7 | 2010-05-10 14:53:29 +0000 | [diff] [blame] | 300 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 301 | with fileinput.input(files=('log1.txt', 'log2.txt')) as f: |
| 302 | for line in f: |
| 303 | process(line) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 304 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 305 | (Contributed by Tarek Ziadé and Giampaolo Rodolà in :issue:`4972`, and |
| 306 | by Georg Brandl in :issue:`8046` and :issue:`1286`.) |
Antoine Pitrou | 696e035 | 2010-08-08 22:18:46 +0000 | [diff] [blame] | 307 | |
Andrew M. Kuchling | 4ea04a3 | 2010-08-18 22:30:34 +0000 | [diff] [blame] | 308 | * The :mod:`os` module now has the :const:`ST_RDONLY` and :const:`ST_NOSUID` |
| 309 | constants, for use with the :func:`~os.statvfs` function. |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 310 | |
Andrew M. Kuchling | 4ea04a3 | 2010-08-18 22:30:34 +0000 | [diff] [blame] | 311 | (Patch by Adam Jackson; :issue:`7647`.) |
| 312 | |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 313 | * The :func:`shutil.copytree` function has two new options: |
| 314 | |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame^] | 315 | * *ignore_dangling_symlinks*: when ``symlinks=False`` so that the function |
| 316 | copies the file pointed to by the symlink, not the symlink itself. This |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 317 | option will silence the error raised if the file doesn't exist. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 318 | |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame^] | 319 | * *copy_function*: is a callable that will be used to copy files. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 320 | :func:`shutil.copy2` is used by default. |
| 321 | |
| 322 | (Contributed by Tarek Ziadé.) |
| 323 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 324 | * Socket objects now have a :meth:`~socket.socket.detach()` method which puts |
| 325 | the socket into closed state without actually closing the underlying file |
| 326 | descriptor. The latter can then be reused for other purposes. |
Antoine Pitrou | e43f9d0 | 2010-08-08 23:24:50 +0000 | [diff] [blame] | 327 | |
| 328 | (Added by Antoine Pitrou; :issue:`8524`.) |
| 329 | |
Raymond Hettinger | d881f31 | 2010-09-05 08:54:32 +0000 | [diff] [blame] | 330 | * The :mod:`sqlite3` module has two new capabilities. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 331 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 332 | The :attr:`Connection.in_transit` attribute is true if there is an active |
| 333 | transaction for uncommitted changes. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 334 | |
Raymond Hettinger | d881f31 | 2010-09-05 08:54:32 +0000 | [diff] [blame] | 335 | The :meth:`Connection.enable_load_extension` and |
| 336 | :meth:`Connection.load_extension` methods allows you to load SQLite extensions |
| 337 | from ".so" files. One well-known extension is the fulltext-search extension |
| 338 | distributed with SQLite. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 339 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 340 | (Contributed by R. David Murray and Shashwat Anand; :issue:`8845`.) |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 341 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 342 | * The :mod:`ssl` module has a new class, :class:`~ssl.SSLContext` which serves |
| 343 | as a container for various persistent SSL data, such as protocol settings, |
| 344 | certificates, private keys, and various other options. The |
| 345 | :meth:`~ssl.SSLContext.wrap_socket` method allows to create an SSL socket from |
| 346 | such an SSL context. (Added by Antoine Pitrou; :issue:`8550`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 347 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 348 | The :func:`ssl.wrap_socket` constructor function now takes a *ciphers* |
| 349 | argument that's a string listing the encryption algorithms to be allowed; the |
| 350 | format of the string is described `in the OpenSSL documentation |
| 351 | <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`__. (Added |
| 352 | by Antoine Pitrou; :issue:`8322`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 353 | |
| 354 | Various options have been added to the :mod:`ssl` module, such as |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 355 | :data:`~ssl.OP_NO_SSLv2` which allows to force disabling of the insecure and |
| 356 | obsolete SSLv2 protocol. (Added by Antoine Pitrou; :issue:`4870`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 357 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 358 | Another change makes the extension load all of OpenSSL's ciphers and digest |
| 359 | algorithms so that they're all available. Some SSL certificates couldn't be |
| 360 | verified, reporting an "unknown algorithm" error. (Reported by Beda Kosata, |
| 361 | and fixed by Antoine Pitrou; :issue:`8484`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 362 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 363 | The version of OpenSSL being used is now available as the module attributes |
| 364 | :data:`ssl.OPENSSL_VERSION` (a string), :data:`ssl.OPENSSL_VERSION_INFO` (a |
| 365 | 5-tuple), and :data:`ssl.OPENSSL_VERSION_NUMBER` (an integer). (Added by |
| 366 | Antoine Pitrou; :issue:`8321`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 367 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 368 | * The previously deprecated :func:`string.maketrans` function has been removed |
| 369 | in favor of the static methods, :meth:`bytes.maketrans` and |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 370 | :meth:`bytearray.maketrans`. This change solves the confusion around which |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 371 | types were supported by the :mod:`string` module. Now, :class:`str`, |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 372 | :class:`bytes`, and :class:`bytearray` each have their own **maketrans** and |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 373 | **translate** methods with intermediate translation tables of the appropriate |
| 374 | type. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 375 | |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 376 | (Contributed by Georg Brandl; :issue:`5675`.) |
| 377 | |
Giampaolo Rodolà | 42382fe | 2010-08-17 16:09:53 +0000 | [diff] [blame] | 378 | * :class:`~poplib.POP3_SSL` class now accepts a *context* parameter, which is a |
| 379 | :class:`ssl.SSLContext` object allowing bundling SSL configuration options, |
| 380 | certificates and private keys into a single (potentially long-lived) |
| 381 | structure. |
| 382 | |
| 383 | (Contributed by Giampaolo Rodolà; :issue:`8807`.) |
| 384 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 385 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 386 | Multi-threading |
| 387 | =============== |
| 388 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 389 | * The mechanism for serializing execution of concurrently running Python threads |
| 390 | (generally known as the GIL or Global Interpreter Lock) has been rewritten. |
| 391 | Among the objectives were more predictable switching intervals and reduced |
| 392 | overhead due to lock contention and the number of ensuing system calls. The |
| 393 | notion of a "check interval" to allow thread switches has been abandoned and |
| 394 | replaced by an absolute duration expressed in seconds. This parameter is |
| 395 | tunable through :func:`sys.setswitchinterval()`. It currently defaults to 5 |
| 396 | milliseconds. |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 397 | |
| 398 | Additional details about the implementation can be read from a `python-dev |
| 399 | mailing-list message |
| 400 | <http://mail.python.org/pipermail/python-dev/2009-October/093321.html>`_ |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 401 | (however, "priority requests" as exposed in this message have not been kept |
| 402 | for inclusion). |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 403 | |
Georg Brandl | 5e73a81 | 2010-04-22 07:02:51 +0000 | [diff] [blame] | 404 | (Contributed by Antoine Pitrou.) |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 405 | |
Antoine Pitrou | 5bab508 | 2009-11-13 22:58:45 +0000 | [diff] [blame] | 406 | * Recursive locks (created with the :func:`threading.RLock` API) now benefit |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 407 | from a C implementation which makes them as fast as regular locks, and between |
| 408 | 10x and 15x faster than their previous pure Python implementation. |
Antoine Pitrou | 5bab508 | 2009-11-13 22:58:45 +0000 | [diff] [blame] | 409 | |
| 410 | (Contributed by Antoine Pitrou; :issue:`3001`.) |
| 411 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 412 | * Regular and recursive locks now accept an optional *timeout* argument to their |
| 413 | ``acquire`` method. (Contributed by Antoine Pitrou; :issue:`7316`.) |
| 414 | |
Antoine Pitrou | e95a9ff | 2010-05-04 23:31:41 +0000 | [diff] [blame] | 415 | Similarly, :meth:`threading.Semaphore.acquire` also gains a *timeout* |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 416 | argument. (Contributed by Torsten Landschoff; :issue:`850728`.) |
Antoine Pitrou | e95a9ff | 2010-05-04 23:31:41 +0000 | [diff] [blame] | 417 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 418 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 419 | Optimizations |
| 420 | ============= |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 421 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 422 | A number of small performance enhancements have been added: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 423 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 424 | * JSON decoding performance is improved and memory consumption is reduced |
| 425 | whenever the same string is repeated for multiple keys. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 426 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 427 | (Contributed by Antoine Pitrou; :issue:`7451`.) |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 428 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 429 | - Python's peephole optimizer now recognizes patterns such ``x in {1, 2, 3}`` as |
| 430 | being a test for membership in a set of constants. The optimizer recasts the |
| 431 | :class:`set` as a :class:`frozenset` and stores the pre-built constant. |
| 432 | |
| 433 | Now that the speed penalty is gone, it is practical to start writing |
| 434 | membership tests using set-notation. This style is both semantically clear |
| 435 | and operationally fast:: |
| 436 | |
| 437 | extension = name.rpartition('.')[2] |
| 438 | if extension in {'xml', 'html', 'xhtml', 'css'}: |
| 439 | handle(name) |
| 440 | |
| 441 | (Patch and additional tests by Dave Malcolm; :issue:`6690`). |
| 442 | |
| 443 | * The fast-search algorithm in stringlib is now used by the :meth:`split`, |
| 444 | :meth:`rsplit`, :meth:`splitlines` and :meth:`replace` methods on |
| 445 | :class:`bytes`, :class:`bytearray` and :class:`str` objects. Likewise, the |
| 446 | algorithm is also used by :meth:`rfind`, :meth:`rindex`, :meth:`rsplit` and |
| 447 | :meth:`rpartition`. |
| 448 | |
| 449 | (Patch by Florent Xicluna in :issue:`7622` and :issue:`7462`.) |
| 450 | |
| 451 | Filenames and Unicode |
Victor Stinner | e8d5145 | 2010-08-19 01:05:19 +0000 | [diff] [blame] | 452 | ===================== |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 453 | |
| 454 | The filesystem encoding can be specified by setting the |
Éric Araujo | 358b63a | 2010-08-18 22:35:23 +0000 | [diff] [blame] | 455 | :envvar:`PYTHONFSENCODING` environment variable before running the interpreter. |
Victor Stinner | 9802b39 | 2010-08-19 11:36:43 +0000 | [diff] [blame] | 456 | The value is an encoding name, e.g. ``iso-8859-1``. This variable is not |
| 457 | available (ignored) on Windows and Mac OS X: the filesystem encoding is pinned |
| 458 | to ``'mbcs'`` on Windows and ``'utf-8'`` on Mac OS X. |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 459 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 460 | The :mod:`os` module has two new functions: :func:`~os.fsencode` and |
| 461 | :func:`~os.fsdecode`. |
Victor Stinner | e8d5145 | 2010-08-19 01:05:19 +0000 | [diff] [blame] | 462 | |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 463 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 464 | .. IDLE |
| 465 | ==== |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 466 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 467 | * Stub |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 468 | |
| 469 | |
| 470 | Build and C API Changes |
| 471 | ======================= |
| 472 | |
| 473 | Changes to Python's build process and to the C API include: |
| 474 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 475 | * The C functions that access the Unicode Database now accept and return |
| 476 | characters from the full Unicode range, even on narrow unicode builds |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 477 | (Py_UNICODE_TOLOWER, Py_UNICODE_ISDECIMAL, and others). A visible difference |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 478 | in Python is that :func:`unicodedata.numeric` now returns the correct value |
| 479 | for large code points, and :func:`repr` may consider more characters as |
| 480 | printable. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 481 | |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 482 | (Reported by Bupjoe Lee and fixed by Amaury Forgeot D'Arc; :issue:`5127`.) |
| 483 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 484 | * Computed gotos are now enabled by default on supported compilers (which are |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame^] | 485 | detected by the configure script). They can still be disabled selectively by |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 486 | specifying ``--without-computed-gotos``. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 487 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 488 | (Contributed by Antoine Pitrou; :issue:`9203`.) |
| 489 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 490 | |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 491 | Porting to Python 3.2 |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 492 | ===================== |
| 493 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 494 | This section lists previously described changes and other bugfixes that may |
| 495 | require changes to your code: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 496 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 497 | * :class:`bytearray` objects cannot be used anymore as filenames: convert them |
| 498 | to :class:`bytes`. |
Victor Stinner | dcb2403 | 2010-04-22 12:08:36 +0000 | [diff] [blame] | 499 | |
Victor Stinner | 25e8ec4 | 2010-06-25 00:02:38 +0000 | [diff] [blame] | 500 | * PyArg_Parse*() functions: |
Victor Stinner | 3dcb5ac | 2010-06-08 22:54:19 +0000 | [diff] [blame] | 501 | |
Victor Stinner | 25e8ec4 | 2010-06-25 00:02:38 +0000 | [diff] [blame] | 502 | * "t#" format has been removed: use "s#" or "s*" instead |
| 503 | * "w" and "w#" formats has been removed: use "w*" instead |
| 504 | |
Amaury Forgeot d'Arc | 661730e | 2010-09-03 22:43:08 +0000 | [diff] [blame] | 505 | * The :ctype:`PyCObject` type, deprecated in 3.1, has been removed. To wrap |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 506 | opaque C pointers in Python objects, the :ctype:`PyCapsule` API should be used |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 507 | instead; the new type has a well-defined interface for passing typing safety |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 508 | information and a less complicated signature for calling a destructor. |