Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +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 |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 14 | get rewritten. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 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 | |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 50 | This article explains the new features in Python 3.2 as compared to 3.1. It |
| 51 | focuses on a few highlights and gives a few examples. For full details, see the |
| 52 | :source:`Misc/NEWS <Misc/NEWS>` file. |
Raymond Hettinger | 2c1ecc3 | 2010-12-07 09:55:02 +0000 | [diff] [blame] | 53 | |
Raymond Hettinger | 6778fa9 | 2010-12-21 20:09:55 +0000 | [diff] [blame] | 54 | .. seealso:: |
| 55 | |
| 56 | :pep:`392` - Python 3.2 Release Schedule |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 57 | |
Martin v. Löwis | 932e49e | 2010-12-04 13:49:32 +0000 | [diff] [blame] | 58 | PEP 384: Defining a Stable ABI |
Martin v. Löwis | 4d0d471 | 2010-12-03 20:14:31 +0000 | [diff] [blame] | 59 | ============================== |
| 60 | |
| 61 | In the past, extension modules built for one Python version were often |
| 62 | not usable with other Python versions. Particularly on Windows, every |
| 63 | feature release of Python required rebuilding all extension modules that |
| 64 | one wanted to use. This requirement was the result of the free access to |
| 65 | Python interpreter internals that extension modules could use. |
| 66 | |
| 67 | With Python 3.2, an alternative approach becomes available: extension |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 68 | modules which restrict themselves to a limited API (by defining |
Martin v. Löwis | 4d0d471 | 2010-12-03 20:14:31 +0000 | [diff] [blame] | 69 | Py_LIMITED_API) cannot use many of the internals, but are constrained |
| 70 | to a set of API functions that are promised to be stable for several |
| 71 | releases. As a consequence, extension modules built for 3.2 in that |
| 72 | mode will also work with 3.3, 3.4, and so on. Extension modules that |
| 73 | make use of details of memory structures can still be built, but will |
| 74 | need to be recompiled for every feature release. |
| 75 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 76 | .. seealso:: |
| 77 | |
Georg Brandl | 65b2eb9 | 2010-12-05 11:42:38 +0000 | [diff] [blame] | 78 | :pep:`384` - Defining a Stable ABI |
Raymond Hettinger | 2c1ecc3 | 2010-12-07 09:55:02 +0000 | [diff] [blame] | 79 | PEP written by Martin von Löwis. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 80 | |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 81 | PEP 389: Argparse Command Line Parsing Module |
| 82 | ============================================= |
| 83 | |
| 84 | A new module for command line parsing, :mod:`argparse`, was introduced to |
| 85 | overcome the limitations of :mod:`optparse` which did not provide support for |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 86 | positional arguments (not just options), subcommands, required options and other |
Raymond Hettinger | 413abbc | 2010-12-05 07:06:47 +0000 | [diff] [blame] | 87 | common patterns of specifying and validating options. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 88 | |
| 89 | This module has already has wide-spread success in the community as a |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 90 | third-party module. Being more fully featured than its predecessor, the |
| 91 | :mod:`argparse` module is now the preferred module for command-line processing. |
| 92 | The older module is still being kept available because of the substantial amount |
| 93 | of legacy code that depends on it. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 94 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 95 | Here's an annotated example parser showing features like limiting results to a |
| 96 | set of choices, specifying a *metavar* in the help screen, validating that one |
Raymond Hettinger | 68f1e8d | 2010-12-07 09:24:30 +0000 | [diff] [blame] | 97 | or more positional arguments is present, and making a required option:: |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 98 | |
| 99 | import argparse |
| 100 | parser = argparse.ArgumentParser( |
| 101 | description = 'Manage servers', # main description for help |
| 102 | epilog = 'Tested on Solaris and Linux') # displayed after help |
| 103 | parser.add_argument('action', # argument name |
| 104 | choices = ['deploy', 'start', 'stop'], # one of four allowed values |
| 105 | help = 'action on each target') # help msg |
| 106 | parser.add_argument('targets', |
| 107 | metavar = 'HOSTNAME', # var name used in help msg |
| 108 | nargs = '+', # require 1 or more targets |
| 109 | help = 'url for target machines') # help msg explanation |
| 110 | parser.add_argument('-u', '--user', # -u or --user option |
| 111 | required = True, # make this a required argument |
| 112 | help = 'login as user') |
| 113 | |
| 114 | Example of calling the parser on a command string:: |
| 115 | |
| 116 | >>> cmd = 'deploy sneezy.example.com sleepy.example.com -u skycaptain' |
| 117 | >>> result = parser.parse_args(cmd.split()) |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 118 | >>> result.action |
| 119 | 'deploy' |
| 120 | >>> result.targets |
| 121 | ['sneezy.example.com', 'sleepy.example.com'] |
| 122 | >>> result.user |
| 123 | 'skycaptain' |
| 124 | |
| 125 | Example of the parser's automatically generated help:: |
| 126 | |
| 127 | >>> parser.parse_args('-h'.split()) |
| 128 | |
Raymond Hettinger | 3fcf002 | 2010-12-08 01:13:53 +0000 | [diff] [blame] | 129 | usage: manage_cloud.py [-h] -u USER |
| 130 | {deploy,start,stop} HOSTNAME [HOSTNAME ...] |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 131 | |
| 132 | Manage servers |
| 133 | |
| 134 | positional arguments: |
| 135 | {deploy,start,stop} action on each target |
| 136 | HOSTNAME url for target machines |
| 137 | |
| 138 | optional arguments: |
| 139 | -h, --help show this help message and exit |
| 140 | -u USER, --user USER login as user |
| 141 | |
| 142 | Tested on Solaris and Linux |
| 143 | |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 144 | An especially nice :mod:`argparse` feature is the ability to define subparsers, |
| 145 | each with their own argument patterns and help displays:: |
| 146 | |
| 147 | import argparse |
| 148 | parser = argparse.ArgumentParser(prog='HELM') |
| 149 | subparsers = parser.add_subparsers() |
| 150 | |
| 151 | parser_l = subparsers.add_parser('launch', help='Launch Control') # first subgroup |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 152 | parser_l.add_argument('-m', '--missiles', action='store_true') |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 153 | parser_l.add_argument('-t', '--torpedos', action='store_true') |
| 154 | |
Raymond Hettinger | 3094ed8 | 2010-12-18 09:41:32 +0000 | [diff] [blame] | 155 | parser_m = subparsers.add_parser('move', help='Move Vessel', # second subgroup |
| 156 | aliases=('steer', 'turn')) # equivalent names |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 157 | parser_m.add_argument('-c', '--course', type=int, required=True) |
| 158 | parser_m.add_argument('-s', '--speed', type=int, default=0) |
| 159 | |
| 160 | $ ./helm.py --help # top level help (launch and move) |
| 161 | $ ./helm.py launch --help # help for launch options |
| 162 | $ ./helm.py launch --missiles # set missiles=True and torpedos=False |
Raymond Hettinger | 3094ed8 | 2010-12-18 09:41:32 +0000 | [diff] [blame] | 163 | $ ./helm.py steer --course 180 --speed 5 # set movement parameters |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 164 | |
| 165 | .. seealso:: |
| 166 | |
| 167 | :pep:`389` - New Command Line Parsing Module |
| 168 | PEP written by Steven Bethard. |
| 169 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 170 | :ref:`upgrading-optparse-code` for details on the differences from |
| 171 | :mod:`optparse`. |
| 172 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 173 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 174 | PEP 391: Dictionary Based Configuration for Logging |
| 175 | ==================================================== |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 176 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 177 | The :mod:`logging` module provided two kinds of configuration, one style with |
| 178 | function calls for each option or another style driven by an external file saved |
| 179 | in a :mod:`ConfigParser` format. Those options did not provide the flexibility |
Georg Brandl | 9e75cad | 2010-09-06 06:45:47 +0000 | [diff] [blame] | 180 | to create configurations from JSON or YAML files, nor did they support |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 181 | incremental configuration, which is needed for specifying logger options from a |
| 182 | command line. |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 183 | |
| 184 | To support a more flexible style, the module now offers |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 185 | :func:`logging.config.dictConfig` for specifying logging configuration with |
| 186 | plain Python dictionaries. The configuration options include formatters, |
| 187 | handlers, filters, and loggers. Here's a working example of a configuration |
| 188 | dictionary:: |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 189 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 190 | {"version": 1, |
| 191 | "formatters": {"brief": {"format": "%(levelname)-8s: %(name)-15s: %(message)s"}, |
| 192 | "full": {"format": "%(asctime)s %(name)-15s %(levelname)-8s %(message)s"}, |
| 193 | }, |
| 194 | "handlers": {"console": { |
| 195 | "class": "logging.StreamHandler", |
| 196 | "formatter": "brief", |
| 197 | "level": "INFO", |
| 198 | "stream": "ext://sys.stdout"}, |
| 199 | "console_priority": { |
| 200 | "class": "logging.StreamHandler", |
| 201 | "formatter": "full", |
| 202 | "level": "ERROR", |
| 203 | "stream": "ext://sys.stderr"}, |
| 204 | }, |
| 205 | "root": {"level": "DEBUG", "handlers": ["console", "console_priority"]}} |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 206 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 207 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 208 | If that dictionary is stored in a file called :file:`conf.json`, it can loaded |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 209 | and called with code like this:: |
| 210 | |
| 211 | >>> import logging.config |
| 212 | >>> logging.config.dictConfig(json.load(open('conf.json', 'rb'))) |
| 213 | >>> logging.info("Transaction completed normally") |
| 214 | >>> logging.critical("Abnormal termination") |
| 215 | |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 216 | .. seealso:: |
| 217 | |
| 218 | :pep:`391` - Dictionary Based Configuration for Logging |
| 219 | PEP written by Vinay Sajip. |
| 220 | |
Georg Brandl | 97b20da | 2010-11-16 15:15:29 +0000 | [diff] [blame] | 221 | PEP 3148: The ``concurrent.futures`` module |
| 222 | ============================================ |
| 223 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 224 | Code for creating and managing concurrency is being collected in a new toplevel |
| 225 | namespace, *concurrent*. Its first member is a *futures* package which provides |
| 226 | a uniform high level interface for managing threads and processes. |
| 227 | |
| 228 | The design for :mod:`concurrent.futures` was inspired by |
| 229 | *java.util.concurrent.package*. In that model, a running call and its result |
| 230 | are represented by a :class:`~concurrent.futures.Future` object which abstracts |
| 231 | features common to threads, processes, and remote procedure calls. That object |
| 232 | supports status checks (running or done), timeouts, cancellations, adding |
Raymond Hettinger | 24a0941 | 2010-12-08 06:50:02 +0000 | [diff] [blame] | 233 | callbacks, and access to results or exceptions. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 234 | |
| 235 | The primary offering of the new module is a pair of executor classes for |
| 236 | launching and managing calls. The goal of the executors is to make it easier to |
| 237 | use existing tools for making parallel calls. They save the effort needed to |
| 238 | setup a pool of resources, launch the calls, create a results queue, add |
| 239 | time-out handling, and limit the total number of threads, processes, or remote |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 240 | procedure calls. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 241 | |
| 242 | Ideally, each application should share a single executor across multiple |
| 243 | components so that process and thread limits can be centrally managed. This |
| 244 | solves the design challenge that arises when each component has its own |
| 245 | competing strategy for resource management. |
| 246 | |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 247 | Both classes share a common interface with three methods: |
| 248 | :meth:`~concurrent.futures.Executor.submit` for scheduling a callable and |
| 249 | returning a :class:`~concurrent.futures.Future` object; |
| 250 | :meth:`~concurrent.futures.Executor.map` for scheduling many asynchronous calls |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 251 | at a time, and :meth:`~concurrent.futures.Executor.shutdown` for freeing |
| 252 | resources. The class is a :term:`context manager` and can be used within a |
| 253 | :keyword:`with` statement to assure that resources are automatically released |
| 254 | when currently pending futures are done executing. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 255 | |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 256 | A simple of example of :class:`~concurrent.futures.ThreadPoolExecutor` is a |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 257 | launch of four parallel threads for copying files:: |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 258 | |
| 259 | import shutil |
| 260 | with ThreadPoolExecutor(max_workers=4) as e: |
| 261 | e.submit(shutil.copy, 'src1.txt', 'dest1.txt') |
| 262 | e.submit(shutil.copy, 'src2.txt', 'dest2.txt') |
| 263 | e.submit(shutil.copy, 'src3.txt', 'dest3.txt') |
| 264 | e.submit(shutil.copy, 'src3.txt', 'dest4.txt') |
| 265 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 266 | .. seealso:: |
| 267 | |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 268 | :pep:`3148` - Futures -- Execute Computations Asynchronously |
Andrew M. Kuchling | 42877fe | 2010-12-15 02:37:01 +0000 | [diff] [blame] | 269 | PEP written by Brian Quinlan. |
Georg Brandl | 97b20da | 2010-11-16 15:15:29 +0000 | [diff] [blame] | 270 | |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 271 | :ref:`Code for Threaded Parallel URL reads<threadpoolexecutor-example>`, an |
| 272 | example using threads to fetch multiple web pages in parallel. |
| 273 | |
| 274 | :ref:`Code for computing prime numbers in |
| 275 | parallel<processpoolexecutor-example>`, an example demonstrating |
| 276 | :class:`~concurrent.futures.ProcessPoolExecutor`. |
| 277 | |
| 278 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 279 | |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 280 | PEP 3147: PYC Repository Directories |
| 281 | ===================================== |
| 282 | |
David Malcolm | 778645a | 2010-12-07 00:32:04 +0000 | [diff] [blame] | 283 | Python's scheme for caching bytecode in *.pyc* files did not work well in |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 284 | environments with multiple python interpreters. If one interpreter encountered |
| 285 | a cached file created by another interpreter, it would recompile the source and |
| 286 | overwrite the cached file, thus losing the benefits of caching. |
| 287 | |
| 288 | 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] | 289 | commonplace for Linux distributions to ship with multiple versions of Python. |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 290 | These conflicts also arise with CPython alternatives such as Unladen Swallow. |
| 291 | |
| 292 | 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] | 293 | distinct filenames for each interpreter. Instead of Python 3.2 and Python 3.3 and |
| 294 | 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] | 295 | look for "mymodule.cpython-32.pyc", "mymodule.cpython-33.pyc", and |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 296 | "mymodule.unladen10.pyc". And to prevent all of these new files from |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 297 | cluttering source directories, the *pyc* files are now collected in a |
| 298 | "__pycache__" directory stored under the package directory. |
| 299 | |
| 300 | Aside from the filenames and target directories, the new scheme has a few |
| 301 | aspects that are visible to the programmer: |
| 302 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 303 | * Imported modules now have a :attr:`__cached__` attribute which stores the name |
| 304 | of the actual file that was imported: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 305 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 306 | >>> import collections |
| 307 | >>> collections.__cached__ |
| 308 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 309 | |
| 310 | * 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] | 311 | module: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 312 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 313 | >>> import imp |
| 314 | >>> imp.get_tag() |
| 315 | 'cpython-32' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 316 | |
| 317 | * Scripts that try to deduce source filename from the imported file now need to |
| 318 | be smarter. It is no longer sufficient to simply strip the "c" from a ".pyc" |
| 319 | filename. Instead, use the new functions in the :mod:`imp` module: |
| 320 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 321 | >>> imp.source_from_cache('c:/py32/lib/__pycache__/collections.cpython-32.pyc') |
| 322 | 'c:/py32/lib/collections.py' |
| 323 | >>> imp.cache_from_source('c:/py32/lib/collections.py') |
| 324 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 325 | |
| 326 | * The :mod:`py_compile` and :mod:`compileall` modules have been updated to |
| 327 | reflect the new naming convention and target directory. |
| 328 | |
| 329 | .. seealso:: |
| 330 | |
| 331 | :pep:`3147` - PYC Repository Directories |
| 332 | PEP written by Barry Warsaw. |
| 333 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 334 | |
Georg Brandl | 3ad4675 | 2010-12-05 07:59:29 +0000 | [diff] [blame] | 335 | PEP 3149: ABI Version Tagged .so Files |
| 336 | ====================================== |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 337 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 338 | The PYC repository directory allows multiple bytecode cache files to be |
| 339 | co-located. This PEP implements a similar mechanism for shared object files by |
| 340 | giving them a common directory and distinct names for each version. |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 341 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 342 | The common directory is "pyshared" and the file names are made distinct by |
| 343 | identifying the Python implementation (such as CPython, PyPy, Jython, etc.), the |
| 344 | 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] | 345 | 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] | 346 | you may see these files when the distribution package is installed:: |
| 347 | |
| 348 | /usr/share/pyshared/foo.cpython-32m.so |
| 349 | /usr/share/pyshared/foo.cpython-33md.so |
| 350 | |
| 351 | In Python itself, the tags are accessible from functions in the :mod:`sysconfig` |
| 352 | module:: |
| 353 | |
| 354 | >>> import sysconfig |
| 355 | >>> sysconfig.get_config_var('SOABI') # find the version tag |
| 356 | 'cpython-32mu' |
| 357 | >>> sysconfig.get_config_var('SO') # find the full filename extension |
| 358 | 'cpython-32mu.so' |
| 359 | |
| 360 | .. seealso:: |
| 361 | |
| 362 | :pep:`3149` - ABI Version Tagged .so Files |
| 363 | PEP written by Barry Warsaw. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 364 | |
| 365 | |
| 366 | Other Language Changes |
| 367 | ====================== |
| 368 | |
| 369 | Some smaller changes made to the core Python language are: |
| 370 | |
Raymond Hettinger | e5e1a98 | 2010-12-05 08:35:21 +0000 | [diff] [blame] | 371 | * String formatting for :func:`format` and :meth:`str.format` gained new |
| 372 | capabilities for the format character **#**. Previously, for integers in |
| 373 | binary, octal, or hexadecimal, it caused the output to be prefixed with '0b', |
| 374 | '0o', or '0x' respectively. Now it can also handle floats, complex, and |
| 375 | Decimal, causing the output to always have a decimal point even when no digits |
| 376 | follow it. |
Raymond Hettinger | e5e728b | 2010-12-05 06:35:16 +0000 | [diff] [blame] | 377 | |
| 378 | >>> format(20, '#o') |
| 379 | '0o24' |
| 380 | >>> format(12.34, '#5.0f') |
| 381 | ' 12.' |
| 382 | |
| 383 | (Suggested by Mark Dickinson and implemented by Eric Smith in :issue:`7094`.) |
Raymond Hettinger | 43b5a85 | 2010-12-05 04:04:21 +0000 | [diff] [blame] | 384 | |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 385 | * The interpreter can now be started with a quiet option, ``-q``, to suppress |
| 386 | the copyright and version information in an interactive mode. |
| 387 | |
| 388 | (Contributed by Marcin Wojdyr in issue:`1772833`). |
| 389 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 390 | * The :func:`hasattr` function used to catch and suppress any Exception. Now, |
| 391 | it only catches :exc:`AttributeError`. Under the hood, :func:`hasattr` works |
| 392 | by calling :func:`getattr` and throwing away the results. This is necessary |
| 393 | because dynamic attribute creation is possible using :meth:`__getattribute__` |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 394 | or :meth:`__getattr__`. If :func:`hasattr` were to just scan instance and class |
Éric Araujo | cc6aac6 | 2010-09-07 21:35:35 +0000 | [diff] [blame] | 395 | dictionaries it would miss the dynamic methods and make it difficult to |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 396 | implement proxy objects. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 397 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 398 | (Discovered by Yury Selivanov and fixed by Benjamin Peterson; :issue:`9666`.) |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 399 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 400 | * 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] | 401 | :func:`repr`. Previously, the :func:`str` form was shorter but that just |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 402 | caused confusion and is no longer needed now that the shortest possible |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 403 | :func:`repr` is displayed by default: |
Raymond Hettinger | bb734c6 | 2010-09-05 05:56:44 +0000 | [diff] [blame] | 404 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 405 | >>> repr(math.pi) |
| 406 | '3.141592653589793' |
| 407 | >>> str(math.pi) |
| 408 | '3.141592653589793' |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 409 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 410 | (Proposed and implemented by Mark Dickinson; :issue:`9337`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 411 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 412 | * :class:`memoryview` objects now have a :meth:`~memoryview.release()` method |
| 413 | and they also now support the context manager protocol. This allows timely |
| 414 | release of any resources that were acquired when requesting a buffer from the |
| 415 | original object. |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 416 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 417 | >>> with memoryview(b'abcdefgh') as v: |
| 418 | ... print(v.tolist()) |
| 419 | ... |
| 420 | [97, 98, 99, 100, 101, 102, 103, 104] |
| 421 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 422 | (Added by Antoine Pitrou; :issue:`9757`.) |
| 423 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 424 | |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 425 | * Previously it was illegal to delete a name from the local namespace if it |
| 426 | occurs as a free variable in a nested block:: |
| 427 | |
| 428 | >>> def outer(x): |
| 429 | ... def inner(): |
| 430 | ... return x |
| 431 | ... inner() |
| 432 | ... del x |
| 433 | |
| 434 | This is now allowed. Remember that the target of an :keyword:`except` clause |
| 435 | is cleared, so this code which used to work with Python 2.6, raised a |
| 436 | :exc:`SyntaxError` with Python 3.1 and now works again:: |
| 437 | |
| 438 | >>> def f(): |
| 439 | ... def print_error(): |
| 440 | ... print(e) |
| 441 | ... try: |
| 442 | ... something |
| 443 | ... except Exception as e: |
| 444 | ... print_error() |
| 445 | ... # implicit "del e" here |
| 446 | |
| 447 | (See :issue:`4617`.) |
| 448 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 449 | * The internal :c:type:`structsequence` tool now creates subclasses of tuple. |
| 450 | This means that C generated structures like those returned by :func:`os.stat`, |
| 451 | :func:`time.gmtime`, and :func:`sys.version_info` now work like a |
| 452 | :term:`named tuple` and are more interoperable with functions and methods that |
| 453 | expect a tuple as an argument. The is a big step forward in making the C |
| 454 | structures as flexible as their pure Python counterparts. |
| 455 | |
| 456 | (Suggested by Arfrever Frehtes Taifersar Arahesis and implemented |
| 457 | by Benjamin Peterson in :issue:`8413`.) |
| 458 | |
| 459 | * Warnings are now easier control. An :envvar:`PYTHONWARNINGS` environment |
| 460 | variable is now available as an alternative to using ``-W`` at the command |
| 461 | line. |
| 462 | |
| 463 | (Suggested by Barry Warsaw and implemented by Philip Jenvey in :issue:`7301`.) |
| 464 | |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 465 | * A new warning category, :exc:`ResourceWarning`, has been added. It is |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 466 | emitted when potential issues with resource consumption or cleanup |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 467 | are detected. It is silenced by default in normal release builds, but |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 468 | can be enabled through the means provided by the :mod:`warnings` |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 469 | module, or on the command line. |
| 470 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 471 | A :exc:`ResourceWarning` is issued at interpreter shutdown if the |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 472 | :data:`gc.garbage` list isn't empty. This is meant to make the programmer |
| 473 | aware that their code contains object finalization issues. |
| 474 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 475 | A :exc:`ResourceWarning` is also issued when a :term:`file object` is destroyed |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 476 | without having been explicitly closed. While the deallocator for such |
| 477 | object ensures it closes the underlying operating system resource |
| 478 | (usually, a file descriptor), the delay in deallocating the object could |
| 479 | produce various issues, especially under Windows. Here is an example |
| 480 | of enabling the warning from the command line:: |
| 481 | |
Raymond Hettinger | 673ccf2 | 2010-12-07 09:37:11 +0000 | [diff] [blame] | 482 | $ ./python -q -Wdefault |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 483 | >>> f = open("foo", "wb") |
| 484 | >>> del f |
| 485 | __main__:1: ResourceWarning: unclosed file <_io.BufferedWriter name='foo'> |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 486 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 487 | (Added by Antoine Pitrou and Georg Brandl in :issue:`10093` and :issue:`477863`.) |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 488 | |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 489 | * :class:`range` objects now support *index* and *count* methods. This is part |
| 490 | of an effort to make more objects fully implement the |
| 491 | :class:`collections.Sequence` :term:`abstract base class`. As a result, the |
| 492 | language will have a more uniform API. In addition, :class:`range` objects |
| 493 | now support slicing and negative indices. This makes *range* more |
Raymond Hettinger | 2ffa671 | 2010-12-08 10:18:21 +0000 | [diff] [blame] | 494 | interoperable with lists:: |
| 495 | |
| 496 | >>> range(0, 100, 2).count(10) |
| 497 | 1 |
| 498 | >>> range(0, 100, 2).index(10) |
| 499 | 5 |
| 500 | >>> range(0, 100, 2)[5] |
| 501 | 10 |
| 502 | >>> range(0, 100, 2)[0:5] |
| 503 | range(0, 10, 2) |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 504 | |
| 505 | (Contributed by Daniel Stuzback in :issue:`9213` and by Alexander Belopolsky |
| 506 | in :issue:`2690`.) |
Nick Coghlan | 37ee850 | 2010-12-03 14:26:13 +0000 | [diff] [blame] | 507 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 508 | * The :func:`callable` builtin function from Py2.x was resurrected. It provides |
Raymond Hettinger | b87ba26 | 2010-12-06 04:31:40 +0000 | [diff] [blame] | 509 | a concise, readable alternative to using an :term:`abstract base class` in an |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 510 | expression like ``isinstance(x, collections.Callable)``: |
| 511 | |
| 512 | >>> callable(max) |
| 513 | True |
| 514 | >>> callable(20) |
| 515 | False |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 516 | |
| 517 | (See :issue:`10518`.) |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 518 | |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 519 | * Python's import mechanism can now load module installed in directories with |
| 520 | non-ASCII characters in the path name. |
| 521 | |
| 522 | (Required extensive work by Victor Stinner in :issue:`9425`.) |
| 523 | |
| 524 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 525 | New, Improved, and Deprecated Modules |
| 526 | ===================================== |
| 527 | |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 528 | Python's standard library has undergone significant maintenance efforts and |
| 529 | quality improvements. |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 530 | |
| 531 | The biggest news for Python 3.2 is that the :mod:`email` package and |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 532 | :mod:`nntplib` modules now work correctly with the bytes/text model in Python 3. |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 533 | For the first time, there is correct handling of inputs with mixed encodings. |
| 534 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 535 | Throughout the standard library, there has been more careful attention to |
| 536 | encodings and text versus bytes issues. In particular, interactions with the |
| 537 | operating system are now better able to pass non-ASCII data using the Windows |
| 538 | mcbs encoding, locale aware encodings, or UTF-8. |
| 539 | |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 540 | Another significant win is the addition of substantially better support for |
| 541 | *SSL* connections and security certificates. |
| 542 | |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 543 | In addition, more functions and classes now have a :term:`context manager` to |
| 544 | support convenient and reliable resource clean-up using the |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 545 | :keyword:`with`-statement. |
| 546 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 547 | email |
| 548 | ----- |
| 549 | |
| 550 | The usability of the :mod:`email` package in Python 3 has been mostly fixed by |
| 551 | the extensive efforts of R. David Murray. The problem was that emails are |
| 552 | typically read and stored in the form of :class:`bytes` rather than :class:`str` |
| 553 | text, and they may contain multiple encodings within a single email. So, the |
| 554 | email package had to be extended to parse and generate email messages in bytes |
| 555 | format. |
| 556 | |
| 557 | * New functions :func:`~email.message_from_bytes` and |
| 558 | :func:`~email.message_from_binary_file`, and new classes |
| 559 | :class:`~email.parser.BytesFeedParser` and :class:`~email.parser.BytesParser` |
| 560 | allow binary message data to be parsed into model objects. |
| 561 | |
| 562 | * Given bytes input to the model, :meth:`~email.message.Message.get_payload` |
| 563 | will by default decode a message body that has a |
| 564 | :mailheader:`Content-Transfer-Encoding` of *8bit* using the charset |
| 565 | specified in the MIME headers and return the resulting string. |
| 566 | |
| 567 | * Given bytes input to the model, :class:`~email.generator.Generator` will |
| 568 | convert message bodies that have a :mailheader:`Content-Transfer-Encoding` of |
| 569 | *8bit* to instead have a *7bit* :mailheader:`Content-Transfer-Encoding`. |
| 570 | |
| 571 | * A new class :class:`~email.generator.BytesGenerator` produces bytes as output, |
| 572 | preserving any unchanged non-ASCII data that was present in the input used to |
| 573 | build the model, including message bodies with a |
| 574 | :mailheader:`Content-Transfer-Encoding` of *8bit*. |
| 575 | |
| 576 | * The :mod:`smtplib` :class:`~smtplib.SMTP` class now accepts a byte string |
| 577 | for the *msg* argument to the :meth:`~smtplib.SMTP.sendmail` method, |
| 578 | and a new method, :meth:`~smtplib.SMTP.send_message` accepts a |
| 579 | :class:`~email.message.Message` object and can optionally obtain the |
| 580 | *from_addr* and *to_addrs* addresses directly from the object. |
| 581 | |
| 582 | .. XXX Update before 3.2rc1 to reflect all of the latest work and add examples. |
| 583 | |
| 584 | (Proposed and implemented by R. David Murray, :issue:`4661` and :issue:`10321`.) |
| 585 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 586 | elementtree |
| 587 | ----------- |
| 588 | |
Georg Brandl | 5d53fdd | 2010-12-18 11:58:12 +0000 | [diff] [blame] | 589 | The :mod:`xml.etree.ElementTree` package and its :mod:`xml.etree.cElementTree` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 590 | counterpart have been updated to version 1.3. |
| 591 | |
| 592 | Several new and useful functions and methods have been added: |
| 593 | |
| 594 | * :func:`xml.etree.ElementTree.fromstringlist` which builds an XML document |
| 595 | from a sequence of fragments |
| 596 | * :func:`xml.etree.ElementTree.register_namespace` for registering a global |
| 597 | namespace prefix |
| 598 | * :func:`xml.etree.ElementTree.tostringlist` for string representation |
| 599 | including all sublists |
| 600 | * :meth:`xml.etree.ElementTree.Element.extend` for appending a sequence of zero |
| 601 | or more elements |
| 602 | * :meth:`xml.etree.ElementTree.Element.iterfind` searches an element and |
| 603 | subelements |
| 604 | * :meth:`xml.etree.ElementTree.Element.itertext` creates a text iterator over |
| 605 | an element and its sub-elements |
| 606 | * :meth:`xml.etree.ElementTree.TreeBuilder.end` closes the current element |
| 607 | * :meth:`xml.etree.ElementTree.TreeBuilder.doctype` handles a doctype |
| 608 | declaration |
| 609 | |
| 610 | Two methods have been deprecated: |
| 611 | |
| 612 | * :meth:`xml.etree.ElementTree.getchildren` use ``list(elem)`` instead. |
| 613 | * :meth:`xml.etree.ElementTree.getiterator` use ``Element.iter`` instead. |
| 614 | |
| 615 | For details of the update, see `Introducing ElementTree |
| 616 | <http://effbot.org/zone/elementtree-13-intro.htm>`_ on Fredrik Lundh's website. |
| 617 | |
Antoine Pitrou | 12de8ac | 2010-12-16 13:33:56 +0000 | [diff] [blame] | 618 | (Contributed by Florent Xicluna and Fredrik Lundh, :issue:`6472`.) |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 619 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 620 | functools |
| 621 | --------- |
| 622 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 623 | * The :mod:`functools` module includes a new decorator for caching function |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 624 | calls. :func:`functools.lru_cache` can save repeated queries to an external |
| 625 | resource whenever the results are expected to be the same. |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 626 | |
Raymond Hettinger | 86f9613 | 2010-08-06 23:23:49 +0000 | [diff] [blame] | 627 | For example, adding a caching decorator to a database query function can save |
| 628 | database accesses for popular searches:: |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 629 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 630 | @functools.lru_cache(maxsize=300) |
| 631 | def get_phone_number(name): |
| 632 | c = conn.cursor() |
| 633 | c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,)) |
| 634 | return c.fetchone()[0] |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 635 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 636 | >>> for name in user_requests: |
Raymond Hettinger | 7496b41 | 2010-11-30 19:15:45 +0000 | [diff] [blame] | 637 | ... get_phone_number(name) # cached lookup |
| 638 | |
| 639 | To help with choosing an effective cache size, the wrapped function is |
| 640 | instrumented for tracking cache statistics: |
| 641 | |
Raymond Hettinger | 5e20bab | 2010-11-30 07:13:04 +0000 | [diff] [blame] | 642 | >>> get_phone_number.cache_info() |
Raymond Hettinger | 7496b41 | 2010-11-30 19:15:45 +0000 | [diff] [blame] | 643 | CacheInfo(hits=4805, misses=980, maxsize=300, currsize=300) |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 644 | |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 645 | 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] | 646 | cleared with: |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 647 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 648 | >>> get_phone_number.cache_clear() |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 649 | |
Raymond Hettinger | 6e35394 | 2010-12-04 23:42:12 +0000 | [diff] [blame] | 650 | (Contributed by Raymond Hettinger and incorporating design ideas from |
Raymond Hettinger | b87ba26 | 2010-12-06 04:31:40 +0000 | [diff] [blame] | 651 | Jim Baker, Miki Tebeka, and Nick Coghlan.) |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 652 | |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 653 | * The :func:`functools.wraps` decorator now adds a :attr:`__wrapped__` attribute |
| 654 | pointing to the original callable function. This allows wrapped functions to |
| 655 | be introspected. It also copies :attr:`__annotations__` if defined. And now |
| 656 | it also gracefully skips over missing attributes such as :attr:`__doc__` which |
Raymond Hettinger | 5eb6390 | 2010-12-09 23:43:34 +0000 | [diff] [blame] | 657 | might not be defined for the wrapped callable. |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 658 | |
| 659 | (By Nick Coghlan and Terrence Cole; :issue:`9567`, :issue:`3445`, and |
| 660 | :issue:`8814`.) |
| 661 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 662 | * To help write classes with rich comparison methods, a new decorator |
| 663 | :func:`functools.total_ordering` will use a existing equality and inequality |
| 664 | methods to fill-in the remaining methods. |
| 665 | |
| 666 | For example, supplying *__eq__* and *__lt__* will enable |
| 667 | :func:`~functools.total_ordering` to fill-in *__le__*, *__gt__* and *__ge__*:: |
| 668 | |
| 669 | @total_ordering |
| 670 | class Student: |
| 671 | def __eq__(self, other): |
| 672 | return ((self.lastname.lower(), self.firstname.lower()) == |
| 673 | (other.lastname.lower(), other.firstname.lower())) |
| 674 | def __lt__(self, other): |
| 675 | return ((self.lastname.lower(), self.firstname.lower()) < |
| 676 | (other.lastname.lower(), other.firstname.lower())) |
| 677 | |
| 678 | (Contributed by Raymond Hettinger.) |
| 679 | |
Raymond Hettinger | f35a34c | 2010-12-22 09:11:54 +0000 | [diff] [blame^] | 680 | .. XXX clarify what the example does |
| 681 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 682 | * To aid in porting programs from Python 2, the :func:`~functools.cmp_to_key` |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 683 | function converts an old-style comparison function to |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 684 | modern :term:`key function`: |
| 685 | |
| 686 | >>> # locale-aware sort order |
| 687 | >>> sorted(iterable, key=cmp_to_key(locale.strcoll)) |
| 688 | |
| 689 | For sorting examples and a brief sorting tutorial, see the `Sorting HowTo |
| 690 | <http://wiki.python.org/moin/HowTo/Sorting/>`_ tutorial. |
| 691 | |
| 692 | (Contributed by Raymond Hettinger.) |
| 693 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 694 | itertools |
| 695 | --------- |
| 696 | |
Raymond Hettinger | 673ccf2 | 2010-12-07 09:37:11 +0000 | [diff] [blame] | 697 | * The :mod:`itertools` module has a new :func:`~itertools.accumulate` function |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 698 | modeled on APL's *scan* operator and on Numpy's *accumulate* function: |
Raymond Hettinger | 6e35394 | 2010-12-04 23:42:12 +0000 | [diff] [blame] | 699 | |
| 700 | >>> list(accumulate(8, 2, 50)) |
| 701 | [8, 10, 60] |
| 702 | |
| 703 | >>> prob_dist = [0.1, 0.4, 0.2, 0.3] |
| 704 | >>> list(accumulate(prob_dist)) # cumulative probability distribution |
| 705 | [0.1, 0.5, 0.7, 1.0] |
| 706 | |
| 707 | For an example using :func:`~itertools.accumulate`, see the :ref:`examples for |
| 708 | the random module <random-examples>`. |
| 709 | |
| 710 | (Contributed by Raymond Hettinger and incorporating design suggestions |
| 711 | from Mark Dickinson.) |
| 712 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 713 | collections |
| 714 | ----------- |
| 715 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 716 | * The :class:`collections.Counter` class now has two forms of in-place |
| 717 | subtraction, the existing *-=* operator for `saturating subtraction |
| 718 | <http://en.wikipedia.org/wiki/Saturation_arithmetic>`_ and the new |
| 719 | :meth:`~collections.Counter.subtract` method for regular subtraction. The |
| 720 | former is suitable for `multisets <http://en.wikipedia.org/wiki/Multiset>`_ |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 721 | which only have positive counts, and the latter is more suitable for use cases |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 722 | that allow negative counts: |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 723 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 724 | >>> tally = Counter(dogs=5, cat=3) |
| 725 | >>> tally -= Counter(dogs=2, cats=8) # saturating subtraction |
| 726 | >>> tally |
| 727 | Counter({'dogs': 3}) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 728 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 729 | >>> tally = Counter(dogs=5, cats=3) |
| 730 | >>> tally.subtract(dogs=2, cats=8) # regular subtraction |
| 731 | >>> tally |
| 732 | Counter({'dogs': 3, 'cats': -5}) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 733 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 734 | (Contributed by Raymond Hettinger.) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 735 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 736 | * The :class:`collections.OrderedDict` class has a new method |
| 737 | :meth:`~collections.OrderedDict.move_to_end` which takes an existing key and |
| 738 | moves it to either the beginning or end of an ordered sequence. When the |
| 739 | dictionary sequence is being used as a queue, these operations correspond to |
| 740 | "move to the front of the line" or "move to the back of the line": |
| 741 | |
| 742 | >>> d = OrderedDict.fromkeys(['a', 'b', 'X', 'd', 'e']) |
| 743 | >>> list(d) |
| 744 | ['a', 'b', 'X', 'd', 'e'] |
| 745 | >>> d.move_to_end('X', last=True) |
| 746 | >>> list(d) |
| 747 | ['a', 'b', 'd', 'e', 'X'] |
| 748 | >>> d.move_to_end('X', last=False) |
| 749 | >>> list(d) |
| 750 | ['X', 'a', 'b', 'd', 'e'] |
| 751 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 752 | (Contributed by Raymond Hettinger.) |
| 753 | |
| 754 | * The :class:`collections.deque` grew two new methods :meth:`~collections.deque.count` |
| 755 | and :meth:`collections.deque.reverse` that make them more substitutable for |
| 756 | :class:`list` when needed: |
| 757 | |
| 758 | >>> d = deque('simsalabim') |
| 759 | >>> d.count('s') |
| 760 | 2 |
| 761 | >>> d.reverse() |
| 762 | >>> d |
| 763 | deque(['m', 'i', 'b', 'a', 'l', 'a', 's', 'm', 'i', 's']) |
| 764 | |
| 765 | (Contributed by Raymond Hettinger.) |
| 766 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 767 | datetime |
| 768 | -------- |
| 769 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 770 | * The :mod:`datetime` module has a new type :class:`~datetime.timezone` that |
| 771 | implements the :class:`~datetime.tzinfo` interface by returning a fixed UTC |
| 772 | offset and timezone name. This makes it easier to create timezone aware |
| 773 | datetime objects: |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 774 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 775 | >>> datetime.now(timezone.utc) |
| 776 | datetime.datetime(2010, 12, 8, 21, 4, 2, 923754, tzinfo=datetime.timezone.utc) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 777 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 778 | >>> datetime.strptime("01/01/2000 12:00 +0000", "%m/%d/%Y %H:%M %z") |
| 779 | datetime.datetime(2000, 1, 1, 12, 0, tzinfo=datetime.timezone.utc) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 780 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 781 | * Also, :class:`~datetime.timedelta` objects can now be multiplied by |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 782 | :class:`float` and divided by :class:`float` and :class:`int` objects. |
| 783 | |
| 784 | (Contributed by Alexander Belopolsky in :issue:`1289118`, :issue:`5094` and |
| 785 | :issue:`6641`.) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 786 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 787 | abc |
| 788 | --- |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 789 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 790 | The :mod:`abc` module now supports :func:`~abc.abstractclassmethod` and |
| 791 | :func:`~abc.abstractstaticmethod`. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 792 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 793 | These tools make it possible to define an :term:`Abstract Base Class` that |
| 794 | requires a particular :func:`classmethod` or :func:`staticmethod` to be |
| 795 | implemented. |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 796 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 797 | (Patch submitted by Daniel Urban; :issue:`5867`.) |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 798 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 799 | contextlib |
| 800 | ---------- |
| 801 | |
| 802 | There is a new and slightly mind-blowing tool |
| 803 | :class:`~contextlib.ContextDecorator` that is helpful for creating a |
| 804 | :term:`context manager` that does double-duty as a function decorator. |
| 805 | |
| 806 | As a convenience, this new functionality is used by |
| 807 | :func:`~contextlib.contextmanager` so that no extra effort is needed to support |
| 808 | both roles. |
| 809 | |
| 810 | The basic idea is that both context managers and function decorators can be used |
| 811 | for pre-action and post-action wrappers. Context managers wrap a group of |
| 812 | statements using the :keyword:`with`-statement, and function decorators wrap a |
| 813 | group of statements enclosed in a function. So, occasionally there is a need to |
| 814 | write a pre/post action wrapper that can be used in either role. |
| 815 | |
| 816 | For example, it is sometimes useful to wrap functions or groups of statements |
| 817 | with a logger that can track the time of entry and time of exit. Rather than |
| 818 | writing both a function decorator and a context manager for the task, the |
| 819 | :func:`~contextlib.contextmanager` provides both capabilities in a single |
| 820 | definition: |
| 821 | |
| 822 | >>> import logging |
| 823 | >>> logging.basicConfig(level=logging.INFO) |
| 824 | >>> @contextmanager |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 825 | ... def track_entry_and_exit(name): |
| 826 | ... logging.info('Entering: {}'.format(name)) |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 827 | ... yield |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 828 | ... logging.info('Exiting: {}'.format(name)) |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 829 | |
| 830 | Formerly, this would have only been usable as a context manager: |
| 831 | |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 832 | >>> with track_entry_and_exit('widget loader'): |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 833 | ... print('Some time consuming activity goes here') |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 834 | ... load_widget() |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 835 | |
| 836 | Now, it can be used as a decorator as well: |
| 837 | |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 838 | >>> @track_entry_and_exit('widget loader') |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 839 | ... def activity(): |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 840 | ... print('Some time consuming activity goes here') |
| 841 | ... load_widget() |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 842 | |
| 843 | Trying to fulfill two roles at once places some limitations on the technique. |
| 844 | Context managers normally have the flexibility to return an argument usable by |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 845 | the :keyword:`with`-statement, but there is no parallel for function decorators. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 846 | |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 847 | In the above example, there is not a clean way for the *track_entry_and_exit* |
| 848 | context manager does not have a way to return a logging instance for use in the |
| 849 | body of enclosed statements. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 850 | |
| 851 | (Contributed by Michael Foord in :issue:`9110`.) |
| 852 | |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 853 | decimal and fractions |
| 854 | --------------------- |
| 855 | |
| 856 | Mark Dickinson crafted an elegant and efficient scheme for assuring that |
| 857 | different numeric datatypes will have the same hash value whenever their actual |
| 858 | values are equal (:issue:`8188`):: |
| 859 | |
| 860 | >>> assert hash(Fraction(3, 2)) == hash(1.5) == \ |
| 861 | hash(Decimal("1.5")) == hash(complex(1.5, 0)) |
| 862 | |
| 863 | An early decision to limit the inter-operability of various numeric types has |
| 864 | been relaxed. It is still unsupported (and ill-advised) to to have implicit |
| 865 | mixing in arithmetic expressions such as ``Decimal('1.1') + float('1.1')`` |
| 866 | because the latter loses information in the process of constructing the binary |
| 867 | float. However, since existing floating point value can be converted losslessly |
| 868 | to either a decimal or rational representation, it makes sense to add them to |
| 869 | the constructor and to support mixed-type comparisons. |
| 870 | |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 871 | * The :class:`decimal.Decimal` constructor now accepts :class:`float` objects |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 872 | directly so there in no longer a need to use the :meth:`~decimal.Decimal.from_float` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 873 | method (:issue:`8257`). |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 874 | |
| 875 | * Mixed type comparisons are now fully supported so that |
| 876 | :class:`~decimal.Decimal` objects can be directly compared with :class:`float` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 877 | and :class:`fractions.Fraction` (:issue:`2531` and :issue:`8188`). |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 878 | |
| 879 | Similar changes were made to :class:`fractions.Fraction` so that the |
| 880 | :meth:`~fractions.Fraction.from_float()` and :meth:`~fractions.Fraction.from_decimal` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 881 | methods are no longer needed (:issue:`8294`): |
| 882 | |
| 883 | >>> Decimal(1.1) |
| 884 | Decimal('1.100000000000000088817841970012523233890533447265625') |
| 885 | >>> Fraction(1.1) |
| 886 | Fraction(2476979795053773, 2251799813685248) |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 887 | |
| 888 | Another useful change for the :mod:`decimal` module is that the |
| 889 | :attr:`Context.clamp` attribute is now public. This is useful in creating |
| 890 | contexts that correspond to the decimal interchange formats specified in IEEE |
| 891 | 754 (see :issue:`8540`). |
| 892 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 893 | (Contributed by Mark Dickinson and Raymond Hettinger.) |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 894 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 895 | ftp |
| 896 | --- |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 897 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 898 | The :class:`ftplib.FTP` class now supports the context manager protocol to |
| 899 | unconditionally consume :exc:`socket.error` exceptions and to close the FTP |
| 900 | connection when done:: |
Giampaolo Rodolà | bd576b7 | 2010-05-10 14:53:29 +0000 | [diff] [blame] | 901 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 902 | >>> from ftplib import FTP |
| 903 | >>> with FTP("ftp1.at.proftpd.org") as ftp: |
| 904 | ... ftp.login() |
| 905 | ... ftp.dir() |
| 906 | ... |
| 907 | '230 Anonymous login ok, restrictions apply.' |
| 908 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 . |
| 909 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .. |
| 910 | dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS |
| 911 | dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 912 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 913 | Other file-like objects such as :class:`mmap.mmap` and :func:`fileinput.input` |
| 914 | also grew auto-closing context managers:: |
| 915 | |
| 916 | with fileinput.input(files=('log1.txt', 'log2.txt')) as f: |
| 917 | for line in f: |
| 918 | process(line) |
| 919 | |
| 920 | (Contributed by Tarek Ziadé and Giampaolo Rodolà in :issue:`4972`, and |
| 921 | by Georg Brandl in :issue:`8046` and :issue:`1286`.) |
Antoine Pitrou | 696e035 | 2010-08-08 22:18:46 +0000 | [diff] [blame] | 922 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 923 | .. XXX mention os.popen and subprocess.Popen auto-closing of fds |
Georg Brandl | 3ad4675 | 2010-12-05 07:59:29 +0000 | [diff] [blame] | 924 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 925 | gzip and zipfile |
| 926 | ---------------- |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 927 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 928 | :class:`gzip.GzipFile` now implements the :class:`io.BufferedIOBase` |
| 929 | :term:`abstract base class` (except for ``truncate()``). It also has a |
| 930 | :meth:`~gzip.GzipFile.peek` method and supports unseekable as well as |
| 931 | zero-padded file objects. |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 932 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 933 | The :mod:`gzip` module also gains the :func:`~gzip.compress` and |
| 934 | :func:`~gzip.decompress` functions for easier in-memory compression and |
| 935 | decompression. Keep in mind that text needs to be encoded in to :class:`bytes` |
| 936 | before compressing and decompressing: |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 937 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 938 | >>> s = 'Three shall be the number thou shalt count, ' |
| 939 | >>> s += 'and the number of the counting shall be three' |
| 940 | >>> b = s.encode() # convert to utf-8 |
| 941 | >>> len(b) |
| 942 | 89 |
| 943 | >>> c = gzip.compress(b) |
| 944 | >>> len(c) |
| 945 | 77 |
| 946 | >>> gzip.decompress(c).decode()[:42] # decompress and convert to text |
| 947 | 'Three shall be the number thou shalt count,' |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 948 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 949 | (Contributed by Anand B. Pillai in :issue:`3488`; and by Antoine Pitrou, Nir |
| 950 | Aides and Brian Curtin in :issue:`9962`, :issue:`1675951`, :issue:`7471` and |
| 951 | :issue:`2846`.) |
| 952 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 953 | Also, the :class:`zipfile.ZipExtFile` class was reworked internally to represent |
| 954 | files stored inside an archive. The new implementation is significantly faster |
| 955 | and can be wrapped in a :class:`io.BufferedReader` object for more speedups. It |
| 956 | also solves an issue where interleaved calls to *read* and *readline* gave the |
| 957 | wrong results. |
| 958 | |
| 959 | (Patch submitted by by Nir Aides in :issue:`7610`.) |
| 960 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 961 | shutil |
| 962 | ------ |
| 963 | |
| 964 | The :func:`shutil.copytree` function has two new options: |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 965 | |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame] | 966 | * *ignore_dangling_symlinks*: when ``symlinks=False`` so that the function |
| 967 | 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] | 968 | option will silence the error raised if the file doesn't exist. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 969 | |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame] | 970 | * *copy_function*: is a callable that will be used to copy files. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 971 | :func:`shutil.copy2` is used by default. |
| 972 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 973 | (Contributed by Tarek Ziadé.) |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 974 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 975 | sqlite3 |
| 976 | ------- |
Antoine Pitrou | e43f9d0 | 2010-08-08 23:24:50 +0000 | [diff] [blame] | 977 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 978 | The :mod:`sqlite3` module was updated to version 2.6.0. It has two new capabilities. |
Antoine Pitrou | e43f9d0 | 2010-08-08 23:24:50 +0000 | [diff] [blame] | 979 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 980 | * The :attr:`sqlite3.Connection.in_transit` attribute is true if there is an |
| 981 | active transaction for uncommitted changes. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 982 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 983 | * The :meth:`sqlite3.Connection.enable_load_extension` and |
| 984 | :meth:`sqlite3.Connection.load_extension` methods allows you to load SQLite |
| 985 | extensions from ".so" files. One well-known extension is the fulltext-search |
| 986 | extension distributed with SQLite. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 987 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 988 | (Contributed by R. David Murray and Shashwat Anand; :issue:`8845`.) |
| 989 | |
| 990 | socket |
| 991 | ------ |
| 992 | |
| 993 | The :mod:`socket` module has two new improvements. |
| 994 | |
| 995 | * Socket objects now have a :meth:`~socket.socket.detach()` method which puts |
| 996 | the socket into closed state without actually closing the underlying file |
| 997 | descriptor. The latter can then be reused for other purposes. |
| 998 | (Added by Antoine Pitrou; :issue:`8524`.) |
| 999 | |
| 1000 | * :func:`socket.create_connection` now supports the context manager protocol |
| 1001 | to unconditionally consume :exc:`socket.error` exceptions and to close the |
| 1002 | socket when done. |
| 1003 | (Contributed by Giampaolo Rodolà; :issue:`9794`.) |
| 1004 | |
| 1005 | ssl |
| 1006 | --- |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1007 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1008 | * The :mod:`ssl` module has a new class, :class:`~ssl.SSLContext` which serves |
| 1009 | as a container for various persistent SSL data, such as protocol settings, |
| 1010 | certificates, private keys, and various other options. The |
| 1011 | :meth:`~ssl.SSLContext.wrap_socket` method allows to create an SSL socket from |
| 1012 | such an SSL context. (Added by Antoine Pitrou; :issue:`8550`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1013 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1014 | * A new function, :func:`ssl.match_hostname`, helps implement server identity |
Antoine Pitrou | 0ee4c9f | 2010-10-08 16:46:17 +0000 | [diff] [blame] | 1015 | verification for higher-level protocols by implementing the rules of |
| 1016 | HTTPS (from :rfc:`2818`), which are also suitable for other protocols. |
| 1017 | (Added by Antoine Pitrou, :issue:`1589`). |
| 1018 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1019 | * The :func:`ssl.wrap_socket` constructor function now takes a *ciphers* |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1020 | argument that's a string listing the encryption algorithms to be allowed; the |
| 1021 | format of the string is described `in the OpenSSL documentation |
| 1022 | <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`__. (Added |
| 1023 | by Antoine Pitrou; :issue:`8322`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1024 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1025 | * When linked against a recent enough version of OpenSSL, the :mod:`ssl` |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 1026 | module now supports the Server Name Indication extension to the TLS |
| 1027 | protocol, allowing for several "virtual hosts" using different certificates |
| 1028 | on a single IP/port. This extension is only supported in client mode, |
| 1029 | and is activated by passing the *server_hostname* argument to |
| 1030 | :meth:`SSLContext.wrap_socket`. |
| 1031 | (Added by Antoine Pitrou, :issue:`5639`.) |
| 1032 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1033 | * Various options have been added to the :mod:`ssl` module, such as |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1034 | :data:`~ssl.OP_NO_SSLv2` which allows to force disabling of the insecure and |
| 1035 | obsolete SSLv2 protocol. (Added by Antoine Pitrou; :issue:`4870`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1036 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1037 | * Another change makes the extension load all of OpenSSL's ciphers and digest |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1038 | algorithms so that they're all available. Some SSL certificates couldn't be |
| 1039 | verified, reporting an "unknown algorithm" error. (Reported by Beda Kosata, |
| 1040 | and fixed by Antoine Pitrou; :issue:`8484`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1041 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1042 | * The version of OpenSSL being used is now available as the module attributes |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1043 | :data:`ssl.OPENSSL_VERSION` (a string), :data:`ssl.OPENSSL_VERSION_INFO` (a |
| 1044 | 5-tuple), and :data:`ssl.OPENSSL_VERSION_NUMBER` (an integer). (Added by |
| 1045 | Antoine Pitrou; :issue:`8321`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1046 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1047 | nntp |
| 1048 | ---- |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 1049 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1050 | The :mod:`nntplib` module has a revamped implementation with better bytes and |
| 1051 | unicode semantics as well as more practical APIs. These improvements break |
| 1052 | compatibility with the nntplib version in Python 3.1, which was partly |
| 1053 | dysfunctional in itself. |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 1054 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1055 | (Contributed by Antoine Pitrou in :issue:`9360`) |
| 1056 | |
| 1057 | certificates |
| 1058 | ------------ |
| 1059 | |
| 1060 | :class:`http.client.HTTPSConnection`, :class:`urllib.request.HTTPSHandler` |
| 1061 | and :func:`urllib.request.urlopen` now take optional arguments to allow for |
| 1062 | server certificate checking against a set of Certificate Authorities, |
| 1063 | as recommended in public uses of HTTPS. |
| 1064 | |
| 1065 | (Added by Antoine Pitrou, :issue:`9003`.) |
| 1066 | |
| 1067 | unittest |
| 1068 | -------- |
Antoine Pitrou | afb078d | 2010-11-05 22:18:28 +0000 | [diff] [blame] | 1069 | |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1070 | * The command-line call, ``python -m unittest`` can now accept file paths |
| 1071 | instead of module names for running specific tests (:issue:`10620`). The new |
| 1072 | test discovery can find tests within packages, locating any test importable |
| 1073 | from the top level directory. The top level directory can be specified with |
| 1074 | the `-t` option, a pattern for matching files with ``-p``, and a directory to |
| 1075 | start discovery with ``-s``:: |
| 1076 | |
| 1077 | $ python -m unittest discover -s my_proj_dir -p '_test.py' |
| 1078 | |
| 1079 | (Contributed by Michael Foord.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1080 | |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1081 | * The :mod:`unittest` module has two new methods, |
| 1082 | :meth:`~unittest.TestCase.assertWarns` and |
| 1083 | :meth:`~unittest.TestCase.assertWarnsRegex` to check that a given warning type |
Raymond Hettinger | 413abbc | 2010-12-05 07:06:47 +0000 | [diff] [blame] | 1084 | is triggered by the code under test: |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1085 | |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1086 | >>> with self.assertWarns(DeprecationWarning): |
| 1087 | ... legacy_function('XYZ') |
Ezio Melotti | 2baf1a6 | 2010-11-22 12:56:58 +0000 | [diff] [blame] | 1088 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1089 | Another new method, :meth:`~unittest.TestCase.assertCountEqual` is used to |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 1090 | compare two iterables to determine if their element counts are equal (whether |
| 1091 | the same elements are present with the same number of occurrences regardless |
| 1092 | of order):: |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1093 | |
| 1094 | def test_anagram(self): |
| 1095 | self.assertCountEqual('algorithm', 'logarithm') |
| 1096 | |
| 1097 | A principal feature of the unittest module is an effort to produce meaningful |
| 1098 | diagnostics when a test fails. When possible the failure is recorded along |
| 1099 | with a diff of the output. This is especially helpful for analyzing log files |
| 1100 | of failed test runs. However, since diffs can sometime be voluminous, there is |
| 1101 | a new :attr:`~unittest.TestCase.maxDiff` attribute which sets maximum length of |
| 1102 | diffs. |
| 1103 | |
Raymond Hettinger | 68f1e8d | 2010-12-07 09:24:30 +0000 | [diff] [blame] | 1104 | In addition the naming in the module has undergone a number of clean-ups. For |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1105 | example, :meth:`~unittest.TestCase.assertRegex` is the new name for |
| 1106 | :meth:`~unittest.TestCase.assertRegexpMatches` which was misnamed because the |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1107 | test uses :func:`re.search`, not :func:`re.match`. Other methods using |
| 1108 | regular expressions are now named using short form "Regex" in preference |
| 1109 | to "Regexp" -- this matches the names used in other unittest implementations, |
| 1110 | matches Python's old name for the :mod:`re` module, and it has unambiguous |
| 1111 | camel-casing. |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1112 | |
| 1113 | To improve consistency, some of long-standing method aliases are being |
| 1114 | deprecated in favor of the preferred names: |
| 1115 | |
| 1116 | - replace :meth:`assert_` with :meth:`.assertTrue` |
| 1117 | - replace :meth:`assertEquals` with :meth:`.assertEqual` |
| 1118 | - replace :meth:`assertNotEquals` with :meth:`.assertNotEqual` |
| 1119 | - replace :meth:`assertAlmostEquals` with :meth:`.assertAlmostEqual` |
| 1120 | - replace :meth:`assertNotAlmostEquals` with :meth:`.assertNotAlmostEqual` |
| 1121 | |
| 1122 | Likewise, the ``TestCase.fail*`` methods deprecated in Python 3.1 are expected |
| 1123 | to be removed in Python 3.3. See also the :ref:`deprecated-aliases` section in |
| 1124 | the :mod:`unittest` documentation. |
Ezio Melotti | 2baf1a6 | 2010-11-22 12:56:58 +0000 | [diff] [blame] | 1125 | |
| 1126 | (Contributed by Ezio Melotti; :issue:`9424`.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1127 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1128 | random |
| 1129 | ------ |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1130 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1131 | The integer methods in the :mod:`random` module now do a better job of producing |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1132 | uniform distributions. Previously, they computed selections with |
| 1133 | ``int(n*random())`` which had a slight bias whenever *n* was not a power of two. |
| 1134 | Now, multiple selections are made from a range upto the next power of two and a |
| 1135 | selection is kept only when it falls within the range ``0 <= x < n``. The |
| 1136 | functions and methods affected are :func:`~random.randrange`, |
| 1137 | :func:`~random.randint`, :func:`~random.choice`, :func:`~random.shuffle` and |
| 1138 | :func:`~random.sample`. |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1139 | |
| 1140 | (Contributed by Raymond Hettinger; :issue:`9025`.) |
| 1141 | |
| 1142 | poplib |
| 1143 | ------ |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1144 | |
Giampaolo Rodolà | 42382fe | 2010-08-17 16:09:53 +0000 | [diff] [blame] | 1145 | * :class:`~poplib.POP3_SSL` class now accepts a *context* parameter, which is a |
| 1146 | :class:`ssl.SSLContext` object allowing bundling SSL configuration options, |
| 1147 | certificates and private keys into a single (potentially long-lived) |
| 1148 | structure. |
| 1149 | |
| 1150 | (Contributed by Giampaolo Rodolà; :issue:`8807`.) |
| 1151 | |
Giampaolo Rodolà | 977c707 | 2010-10-04 21:08:36 +0000 | [diff] [blame] | 1152 | * :class:`asyncore.dispatcher` now provides a |
| 1153 | :meth:`~asyncore.dispatcher.handle_accepted()` method |
| 1154 | returning a `(sock, addr)` pair which is called when a connection has actually |
| 1155 | been established with a new remote endpoint. This is supposed to be used as a |
| 1156 | replacement for old :meth:`~asyncore.dispatcher.handle_accept()` and avoids |
| 1157 | the user to call :meth:`~asyncore.dispatcher.accept()` directly. |
| 1158 | |
| 1159 | (Contributed by Giampaolo Rodolà; :issue:`6706`.) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1160 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1161 | tempfile |
| 1162 | -------- |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1163 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1164 | The :mod:`tempfile` module has a new context manager, |
| 1165 | :class:`~tempfile.TemporaryDirectory` which provides easy deterministic |
| 1166 | cleanup of temporary directories: |
Nick Coghlan | 543af75 | 2010-10-24 11:23:25 +0000 | [diff] [blame] | 1167 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1168 | >>> with tempfile.TemporaryDirectory() as tmpdirname: |
| 1169 | ... print 'created temporary directory', tmpdirname |
Nick Coghlan | 543af75 | 2010-10-24 11:23:25 +0000 | [diff] [blame] | 1170 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1171 | (Contributed by Neil Schemenauer and Nick Coghlan; :issue:`5178`.) |
Nick Coghlan | e0f0465 | 2010-11-21 03:44:04 +0000 | [diff] [blame] | 1172 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1173 | inspect |
| 1174 | ------- |
| 1175 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1176 | * The :mod:`inspect` module has a new function |
| 1177 | :func:`~inspect.getgeneratorstate` to easily identify the current state of a |
| 1178 | generator as one of ``GEN_CREATED``, ``GEN_RUNNING``, ``GEN_SUSPENDED`` or |
| 1179 | ``GEN_CLOSED``. (Contributed by Rodolpho Eckhardt and Nick Coghlan, |
| 1180 | :issue:`10220`.) |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1181 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1182 | * To support lookups without the possibility of activating a dynamic attribute, |
| 1183 | the :mod:`inspect` module has a new function, :func:`~inspect.getattr_static`. |
| 1184 | Unlike, :func:`hasattr`, this is a true read-only search, guaranteed not to |
| 1185 | change state while it is searching. (Contributed by Michael Foord.) |
Nick Coghlan | e0f0465 | 2010-11-21 03:44:04 +0000 | [diff] [blame] | 1186 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1187 | pydoc |
| 1188 | ----- |
Nick Coghlan | 7bb30b7 | 2010-12-03 09:29:11 +0000 | [diff] [blame] | 1189 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1190 | The :mod:`pydoc` module now provides a much improved Web server interface, |
| 1191 | as well as a new command-line option to automatically open a browser |
| 1192 | window to display that server. |
Nick Coghlan | 7bb30b7 | 2010-12-03 09:29:11 +0000 | [diff] [blame] | 1193 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1194 | (Contributed by Ron Adam; :issue:`2001`.) |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1195 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1196 | sysconfig |
| 1197 | --------- |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1198 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1199 | The new :mod:`sysconfig` module makes it straight-forward to discover |
| 1200 | installation paths and configuration variables which vary across platforms and |
| 1201 | installations. |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1202 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1203 | The module offers access simple access functions for platform and version |
| 1204 | information: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1205 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1206 | * :func:`~sysconfig.get_platform` returning values like *linux-i586* or |
| 1207 | *macosx-10.6-ppc*. |
| 1208 | * :func:`~sysconfig.get_python_version` returns a Python version string in |
| 1209 | the form, "3.2". |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1210 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1211 | It also provides access to the paths and variables corresponding to one of |
| 1212 | seven named schemes used by :mod:`distutils`. Those include *posix_prefix*, |
| 1213 | *posix_home*, *posix_user*, *nt*, *nt_user*, *os2*, *os2_home*: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1214 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1215 | * :func:`~sysconfig.get_paths` makes a dictionary containing installation paths |
| 1216 | for the current installation scheme. |
| 1217 | * :func:`~sysconfig.get_config_vars` returns a dictionary of platform specific |
| 1218 | variables. |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1219 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1220 | There is also a convenient command-line interface:: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1221 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1222 | C:\Python32>python -m sysconfig |
| 1223 | Platform: "win32" |
| 1224 | Python version: "3.2" |
| 1225 | Current installation scheme: "nt" |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1226 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1227 | Paths: |
| 1228 | data = "C:\Python32" |
Łukasz Langa | 79a06ed | 2010-12-17 22:05:46 +0000 | [diff] [blame] | 1229 | include = "C:\Python32\Include" |
| 1230 | platinclude = "C:\Python32\Include" |
| 1231 | platlib = "C:\Python32\Lib\site-packages" |
| 1232 | platstdlib = "C:\Python32\Lib" |
| 1233 | purelib = "C:\Python32\Lib\site-packages" |
| 1234 | scripts = "C:\Python32\Scripts" |
| 1235 | stdlib = "C:\Python32\Lib" |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1236 | |
| 1237 | Variables: |
| 1238 | BINDIR = "C:\Python32" |
Łukasz Langa | 79a06ed | 2010-12-17 22:05:46 +0000 | [diff] [blame] | 1239 | BINLIBDEST = "C:\Python32\Lib" |
| 1240 | EXE = ".exe" |
| 1241 | INCLUDEPY = "C:\Python32\Include" |
| 1242 | LIBDEST = "C:\Python32\Lib" |
| 1243 | SO = ".pyd" |
| 1244 | VERSION = "32" |
| 1245 | abiflags = "" |
| 1246 | base = "C:\Python32" |
| 1247 | exec_prefix = "C:\Python32" |
| 1248 | platbase = "C:\Python32" |
| 1249 | prefix = "C:\Python32" |
| 1250 | projectbase = "C:\Python32" |
| 1251 | py_version = "3.2" |
| 1252 | py_version_nodot = "32" |
| 1253 | py_version_short = "3.2" |
| 1254 | srcdir = "C:\Python32" |
| 1255 | userbase = "C:\Documents and Settings\Raymond\Application Data\Python" |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1256 | |
| 1257 | pdb |
| 1258 | --- |
| 1259 | |
| 1260 | The :mod:`pdb` debugger module gained a number of usability improvements: |
Raymond Hettinger | b5d7933 | 2010-12-07 02:04:56 +0000 | [diff] [blame] | 1261 | |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1262 | * :file:`pdb.py` now has a ``-c`` option that executes commands as given in a |
| 1263 | :file:`.pdbrc` script file. |
| 1264 | * A :file:`.pdbrc` script file can contain ``continue`` and ``next`` commands |
| 1265 | that continue debugging. |
| 1266 | * The :class:`Pdb` class constructor now accepts a *nosigint* argument. |
| 1267 | * new commands: ``l(list)``, ``ll(long list`` and ``source`` for |
| 1268 | listing source code. |
| 1269 | * new commands: ``display`` and ``undisplay`` for showing or hiding |
| 1270 | the value of an expression if it has changed. |
| 1271 | * new command: ``interact`` for starting an interactive interpreter containing |
| 1272 | the global and local names found in the current scope. |
| 1273 | * breakpoints can be cleared by breakpoint number |
Raymond Hettinger | b5d7933 | 2010-12-07 02:04:56 +0000 | [diff] [blame] | 1274 | |
Georg Brandl | 101234b | 2010-12-18 11:53:25 +0000 | [diff] [blame] | 1275 | (Contributed by Georg Brandl, Antonio Cuni and Ilya Sandler.) |
| 1276 | |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1277 | configparser |
| 1278 | ------------ |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1279 | |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1280 | The :mod:`configparser` module was modified to improve usability and |
| 1281 | predictability of the default parser and its supported INI syntax. The old |
| 1282 | :class:`ConfigParser` class was removed in favor of :class:`SafeConfigParser` |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1283 | which has in turn been renamed to :class:`~configparser.ConfigParser`. Support |
| 1284 | for inline comments is now turned off by default and section or option |
| 1285 | duplicates are not allowed in a single configuration source. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1286 | |
| 1287 | Config parsers gained a new API based on the mapping protocol:: |
| 1288 | |
| 1289 | >>> parser = ConfigParser() |
| 1290 | >>> parser.read_string(""" |
| 1291 | ... [DEFAULT] |
| 1292 | ... monty = python |
| 1293 | ... |
| 1294 | ... [phrases] |
| 1295 | ... the = who |
| 1296 | ... full = metal jacket |
| 1297 | ... """) |
| 1298 | >>> parser['phrases']['full'] |
| 1299 | 'metal jacket' |
| 1300 | >>> section = parser['phrases'] |
| 1301 | >>> section['the'] |
| 1302 | 'who' |
| 1303 | >>> section['british'] = '%(the)s %(full)s %(monty)s!' |
| 1304 | >>> parser['phrases']['british'] |
| 1305 | 'who metal jacket python!' |
| 1306 | >>> 'british' in section |
| 1307 | True |
| 1308 | |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1309 | The new API is implemented on top of the classical API so custom parser |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1310 | subclasses should be able to use it without modifications. |
| 1311 | |
| 1312 | The INI file structure accepted by config parsers can now be customized. Users |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1313 | can specify alternative option/value delimiters and comment prefixes, change the |
| 1314 | name of the *DEFAULT* section or switch the interpolation syntax. Along with |
| 1315 | support for pluggable interpolation, an additional interpolation handler |
| 1316 | :class:`~configparser.ExtendedInterpolation` was introduced:: |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1317 | |
| 1318 | >>> parser = ConfigParser(interpolation=ExtendedInterpolation()) |
| 1319 | >>> parser.read_dict({'buildout': {'directory': '/home/ambv/zope9'}, |
| 1320 | ... 'custom': {'prefix': '/usr/local'}}) |
| 1321 | >>> parser.read_string(""" |
| 1322 | ... [buildout] |
| 1323 | ... parts = |
| 1324 | ... zope9 |
| 1325 | ... instance |
| 1326 | ... find-links = |
| 1327 | ... ${buildout:directory}/downloads/dist |
| 1328 | ... |
| 1329 | ... [zope9] |
| 1330 | ... recipe = plone.recipe.zope9install |
| 1331 | ... location = /opt/zope |
| 1332 | ... |
| 1333 | ... [instance] |
| 1334 | ... recipe = plone.recipe.zope9instance |
| 1335 | ... zope9-location = ${zope9:location} |
| 1336 | ... zope-conf = ${custom:prefix}/etc/zope.conf |
| 1337 | ... """) |
| 1338 | >>> parser['buildout']['find-links'] |
| 1339 | '\n/home/ambv/zope9/downloads/dist' |
| 1340 | >>> parser['instance']['zope-conf'] |
| 1341 | '/usr/local/etc/zope.conf' |
| 1342 | >>> instance = parser['instance'] |
| 1343 | >>> instance['zope-conf'] |
| 1344 | '/usr/local/etc/zope.conf' |
| 1345 | >>> instance['zope9-location'] |
| 1346 | '/opt/zope' |
| 1347 | |
| 1348 | A number of smaller features were also introduced, like support for specifying |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1349 | encoding in read operations, specifying fallback values for get-functions, or |
| 1350 | reading directly from dictionaries and strings. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1351 | |
| 1352 | (All changes contributed by Łukasz Langa.) |
| 1353 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1354 | .. XXX: Mention urllib.parse changes |
| 1355 | Issue 9873 (Nick Coghlan): |
| 1356 | - ASCII byte sequence support in URL parsing |
| 1357 | - named tuple for urldefrag return value |
| 1358 | Issue 5468 (Dan Mahn) for urlencode: |
| 1359 | - bytes input support |
| 1360 | - non-UTF8 percent encoding of non-ASCII characters |
| 1361 | Issue 2987 for IPv6 (RFC2732) support in urlparse |
Raymond Hettinger | 202717d | 2010-12-16 10:06:11 +0000 | [diff] [blame] | 1362 | .. XXX: Any updates to the WSGI bytes versus text problem? |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1363 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1364 | Multi-threading |
| 1365 | =============== |
| 1366 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1367 | * The mechanism for serializing execution of concurrently running Python threads |
| 1368 | (generally known as the GIL or Global Interpreter Lock) has been rewritten. |
| 1369 | Among the objectives were more predictable switching intervals and reduced |
| 1370 | overhead due to lock contention and the number of ensuing system calls. The |
| 1371 | notion of a "check interval" to allow thread switches has been abandoned and |
| 1372 | replaced by an absolute duration expressed in seconds. This parameter is |
| 1373 | tunable through :func:`sys.setswitchinterval()`. It currently defaults to 5 |
| 1374 | milliseconds. |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1375 | |
| 1376 | Additional details about the implementation can be read from a `python-dev |
| 1377 | mailing-list message |
| 1378 | <http://mail.python.org/pipermail/python-dev/2009-October/093321.html>`_ |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1379 | (however, "priority requests" as exposed in this message have not been kept |
| 1380 | for inclusion). |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1381 | |
Georg Brandl | 5e73a81 | 2010-04-22 07:02:51 +0000 | [diff] [blame] | 1382 | (Contributed by Antoine Pitrou.) |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1383 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1384 | * Regular and recursive locks now accept an optional *timeout* argument to their |
Raymond Hettinger | 09e4ebb | 2010-09-06 19:55:51 +0000 | [diff] [blame] | 1385 | :meth:`acquire` method. (Contributed by Antoine Pitrou; :issue:`7316`.) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1386 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1387 | * Similarly, :meth:`threading.Semaphore.acquire` also gained a *timeout* |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1388 | argument. (Contributed by Torsten Landschoff; :issue:`850728`.) |
Antoine Pitrou | e95a9ff | 2010-05-04 23:31:41 +0000 | [diff] [blame] | 1389 | |
Antoine Pitrou | 810023d | 2010-12-15 22:59:16 +0000 | [diff] [blame] | 1390 | * Regular and recursive lock acquisitions can now be interrupted by signals on |
| 1391 | platforms using pthreads. This means that Python programs that deadlock while |
| 1392 | acquiring locks can be successfully killed by repeatedly sending SIGINT to the |
Georg Brandl | eebb252 | 2010-12-18 12:01:15 +0000 | [diff] [blame] | 1393 | process (by pressing :kbd:`Ctrl+C` in most shells). |
Antoine Pitrou | 810023d | 2010-12-15 22:59:16 +0000 | [diff] [blame] | 1394 | (Contributed by Reid Kleckner; :issue:`8844`.) |
| 1395 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1396 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 1397 | Optimizations |
| 1398 | ============= |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1399 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 1400 | A number of small performance enhancements have been added: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1401 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1402 | * Python's peephole optimizer now recognizes patterns such ``x in {1, 2, 3}`` as |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 1403 | being a test for membership in a set of constants. The optimizer recasts the |
| 1404 | :class:`set` as a :class:`frozenset` and stores the pre-built constant. |
| 1405 | |
| 1406 | Now that the speed penalty is gone, it is practical to start writing |
| 1407 | membership tests using set-notation. This style is both semantically clear |
| 1408 | and operationally fast:: |
| 1409 | |
| 1410 | extension = name.rpartition('.')[2] |
| 1411 | if extension in {'xml', 'html', 'xhtml', 'css'}: |
| 1412 | handle(name) |
| 1413 | |
| 1414 | (Patch and additional tests by Dave Malcolm; :issue:`6690`). |
| 1415 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1416 | * Serializing and unserializing data using the :mod:`pickle` module is now |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1417 | several times faster. |
| 1418 | |
| 1419 | (Contributed by Alexandre Vassalotti, Antoine Pitrou |
Antoine Pitrou | ff150f2 | 2010-10-22 21:41:05 +0000 | [diff] [blame] | 1420 | and the Unladen Swallow team in :issue:`9410` and :issue:`3873`.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1421 | |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1422 | * The `Timsort algorithm <http://en.wikipedia.org/wiki/Timsort>`_ used in |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 1423 | :meth:`list.sort` and :func:`sorted` now runs faster and uses less memory |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1424 | when called with a :term:`key function`. Previously, every element of |
| 1425 | a list was wrapped with a temporary object that remembered the key value |
| 1426 | associated with each element. Now, an array of keys and values are |
| 1427 | sorted in parallel. This save the memory consumed by the sort wrappers, |
| 1428 | and it saves time lost from during comparisons which where delegated |
| 1429 | by the sort wrappers. |
| 1430 | |
| 1431 | (Patch by Daniel Stuzback in :issue:`9915`.) |
| 1432 | |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1433 | * JSON decoding performance is improved and memory consumption is reduced |
Raymond Hettinger | 413abbc | 2010-12-05 07:06:47 +0000 | [diff] [blame] | 1434 | whenever the same string is repeated for multiple keys. Also, JSON encoding |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1435 | now uses the C speedups when the ``sort_keys`` argument is true. |
| 1436 | |
| 1437 | (Contributed by Antoine Pitrou in :issue:`7451` and by Raymond Hettinger and |
| 1438 | Antoine Pitrou in :issue:`10314`.) |
| 1439 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1440 | * Recursive locks (created with the :func:`threading.RLock` API) now benefit |
| 1441 | from a C implementation which makes them as fast as regular locks, and between |
| 1442 | 10x and 15x faster than their previous pure Python implementation. |
| 1443 | |
| 1444 | (Contributed by Antoine Pitrou; :issue:`3001`.) |
| 1445 | |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1446 | * The fast-search algorithm in stringlib is now used by the :meth:`split`, |
| 1447 | :meth:`rsplit`, :meth:`splitlines` and :meth:`replace` methods on |
| 1448 | :class:`bytes`, :class:`bytearray` and :class:`str` objects. Likewise, the |
| 1449 | algorithm is also used by :meth:`rfind`, :meth:`rindex`, :meth:`rsplit` and |
| 1450 | :meth:`rpartition`. |
| 1451 | |
| 1452 | (Patch by Florent Xicluna in :issue:`7622` and :issue:`7462`.) |
| 1453 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1454 | |
| 1455 | * String to integer conversions now work two "digits" at a time, reducing the |
| 1456 | number of division and modulo operations. |
| 1457 | |
| 1458 | (:issue:`6713` by Gawain Bolton, Mark Dickinson, and Victor Stinner.) |
| 1459 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 1460 | There were several other minor optimizations. Set differencing now runs faster |
| 1461 | when one operand is much larger than the other (Patch by Andress Bennetts in |
| 1462 | :issue:`8685`). The :meth:`array.repeat` method has a faster implementation |
| 1463 | (:issue:`1569291` by Alexander Belopolsky). The :class:`BaseHTTPRequestHandler` |
| 1464 | has more efficient buffering (:issue:`3709` by Andrew Schaaf). The |
| 1465 | multi-argument form of :func:`operator.attrgetter` now function runs slightly |
| 1466 | faster (:issue:`10160` by Christos Georgiou). And :class:`ConfigParser` loads |
| 1467 | multi-line arguments a bit faster (:issue:`7113` by Łukasz Langa). |
| 1468 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1469 | |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1470 | Unicode |
| 1471 | ======= |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 1472 | |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1473 | Python has been updated to Unicode 6.0.0. The new features of the |
| 1474 | Unicode Standard that will affect Python users include: |
| 1475 | |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1476 | * addition of 2,088 characters, including over 1,000 additional |
| 1477 | symbols—chief among them the additional emoji symbols, which are |
| 1478 | especially important for mobile phones; |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1479 | |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1480 | * changes to character properties for existing characters including |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1481 | |
Raymond Hettinger | c74d518 | 2010-12-02 01:38:25 +0000 | [diff] [blame] | 1482 | - a general category change to two Kannada characters (U+0CF1, |
| 1483 | U+0CF2), which has the effect of making them newly eligible for |
| 1484 | inclusion in identifiers; |
| 1485 | |
| 1486 | - a general category change to one New Tai Lue numeric character |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1487 | (U+19DA), which has the effect of disqualifying it from |
| 1488 | inclusion in identifiers. |
| 1489 | |
| 1490 | For more information, see `Unicode Character Database Changes |
| 1491 | <http://www.unicode.org/versions/Unicode6.0.0/#Database_Changes>`_ |
| 1492 | at the `Unicode Consortium <http://www.unicode.org/>`_ web site. |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1493 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 1494 | The :mod:`os` module has two new functions: :func:`~os.fsencode` and |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1495 | :func:`~os.fsdecode`. Add :data:`os.environb`: bytes version of |
| 1496 | :data:`os.environ`, :func:`os.getenvb` function and |
| 1497 | :data:`os.supports_bytes_environ` constant. |
Victor Stinner | e8d5145 | 2010-08-19 01:05:19 +0000 | [diff] [blame] | 1498 | |
Georg Brandl | 326c57d | 2010-11-26 12:10:06 +0000 | [diff] [blame] | 1499 | ``'mbcs'`` encoding doesn't ignore the error handler argument any more. By |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1500 | default (strict mode), it raises an UnicodeDecodeError on undecodable byte |
| 1501 | sequence and UnicodeEncodeError on unencodable character. To get the ``'mbcs'`` |
| 1502 | encoding of Python 3.1, use ``'ignore'`` error handler to decode and |
| 1503 | ``'replace'`` error handler to encode. ``'mbcs'`` supports ``'strict'`` and |
| 1504 | ``'ignore'`` error handlers for decoding, and ``'strict'`` and ``'replace'`` |
| 1505 | for encoding. |
| 1506 | |
| 1507 | On Mac OS X, Python uses ``'utf-8'`` to decode the command line arguments, |
| 1508 | instead of the locale encoding (which is ISO-8859-1 if the ``LANG`` environment |
| 1509 | variable is not set). |
| 1510 | |
| 1511 | By default, tarfile uses ``'utf-8'`` encoding on Windows (instead of |
| 1512 | ``'mbcs'``), and the ``'surrogateescape'`` error handler on all operating |
| 1513 | systems. |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1514 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1515 | * Added the *cp720* Arabic DOS encoding (:issue:`1616979`). |
| 1516 | |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 1517 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1518 | Documentation |
| 1519 | ============= |
| 1520 | |
| 1521 | The documentation continues to be improved. |
| 1522 | |
| 1523 | A table of quick links has been added to the top of lengthy sections such as |
| 1524 | :ref:`built-in-funcs`. In the case of :mod:`itertools`, the links are |
| 1525 | accompanied by tables of cheatsheet-style summaries to provide an overview and |
| 1526 | memory jog without having to read all of the docs. |
| 1527 | |
| 1528 | In some cases, the pure python source code can be helpful adjunct to the docs, |
| 1529 | so now some modules feature quick links to the latest version of the source |
| 1530 | code. For example, the :mod:`functools` module documentation has a quick link |
| 1531 | at the top labeled :source:`functools Python source code <Lib/functools.py>`. |
| 1532 | |
| 1533 | The docs now contain more examples and recipes. In particular, :mod:`re` module |
| 1534 | has an extensive section, :ref:`re-examples`. Likewise, the :mod:`itertools` |
| 1535 | module continues to be updated with new :ref:`itertools-recipes`. |
| 1536 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 1537 | The :mod:`datetime` module now has an auxiliary implementation in pure Python. |
| 1538 | No functionality was changed. This just provides an easier-to-read |
| 1539 | alternate implementation. (Contributed by Alexander Belopolsky.) |
| 1540 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1541 | |
| 1542 | IDLE |
| 1543 | ==== |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1544 | |
Georg Brandl | cc9d237 | 2010-12-10 19:22:11 +0000 | [diff] [blame] | 1545 | * The format menu now has an option to clean-up source files by stripping |
| 1546 | trailing whitespace (:issue:`5150`). |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1547 | |
| 1548 | |
| 1549 | Build and C API Changes |
| 1550 | ======================= |
| 1551 | |
| 1552 | Changes to Python's build process and to the C API include: |
| 1553 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1554 | * The C functions that access the Unicode Database now accept and return |
| 1555 | characters from the full Unicode range, even on narrow unicode builds |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1556 | (Py_UNICODE_TOLOWER, Py_UNICODE_ISDECIMAL, and others). A visible difference |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1557 | in Python is that :func:`unicodedata.numeric` now returns the correct value |
| 1558 | for large code points, and :func:`repr` may consider more characters as |
| 1559 | printable. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1560 | |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1561 | (Reported by Bupjoe Lee and fixed by Amaury Forgeot D'Arc; :issue:`5127`.) |
| 1562 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1563 | * Computed gotos are now enabled by default on supported compilers (which are |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame] | 1564 | detected by the configure script). They can still be disabled selectively by |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1565 | specifying ``--without-computed-gotos``. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1566 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1567 | (Contributed by Antoine Pitrou; :issue:`9203`.) |
| 1568 | |
Amaury Forgeot d'Arc | feb7307 | 2010-09-12 22:42:57 +0000 | [diff] [blame] | 1569 | * The option ``--with-wctype-functions`` was removed. The built-in unicode |
| 1570 | database is now used for all functions. |
| 1571 | |
| 1572 | (Contributed by Amaury Forgeot D'Arc; :issue:`9210`.) |
| 1573 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1574 | * Hash values are now values of a new type, :c:type:`Py_hash_t`, which is |
| 1575 | defined to be the same size as a pointer. Previously they were of type long, |
| 1576 | which on some 64-bit operating systems is still only 32 bits long. As a |
| 1577 | result of this fix, :class:`set` and :class:`dict` can now hold more than |
| 1578 | ``2**32`` entries on builds with 64-bit pointers (previously, they could grow |
| 1579 | to that size but their performance degraded catastrophically). |
Skip Montanaro | 961aaf5 | 2010-10-17 22:22:24 +0000 | [diff] [blame] | 1580 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1581 | (Suggested by Raymond Hettinger and implemented by Benjamin Peterson; |
| 1582 | :issue:`9778`.) |
| 1583 | |
| 1584 | * A new macro :c:macro:`Py_VA_COPY` copies the state of the variable argument |
| 1585 | list. It is equivalent to C99 *va_copy* but available on all python platforms |
| 1586 | (:issue:`2443`). |
| 1587 | |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 1588 | * A new C API function :c:func:`PySys_SetArgvEx` allows an embedded |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1589 | interpreter to set sys.argv without also modifying :attr:`sys.path` |
| 1590 | (:issue:`5753`). |
| 1591 | |
| 1592 | * :c:macro:`PyEval_CallObject` is now only available in macro form. The |
| 1593 | function declaration, which was kept for backwards compatibility reasons, is |
| 1594 | now removed -- the macro was introduced in 1997 (:issue:`8276`). |
| 1595 | |
| 1596 | * The is a new function :c:func:`PyLong_AsLongLongAndOverflow` which |
| 1597 | is analogous to :c:func:`PyLong_AsLongAndOverflow`. The both serve to |
| 1598 | convert Python :class:`int` into a native fixed-width type while providing |
| 1599 | detection of cases where the conversion won't fit (:issue:`7767`). |
| 1600 | |
| 1601 | * The :c:func:`PyUnicode_CompareWithASCIIString` now returns *not equal* |
| 1602 | if the Python string in *NUL* terminated. |
| 1603 | |
| 1604 | * There is a new function :c:func:`PyErr_NewExceptionWithDoc` that is |
| 1605 | like :c:func:`PyErr_NewException` but allows a docstring to be specified. |
| 1606 | This lets C exceptions have the same self-documenting capabilities as |
| 1607 | their pure Python counterparts (:issue:`7033`). |
| 1608 | |
| 1609 | * When compiled with the ``--with-valgrind`` option, the pymalloc |
| 1610 | allocator will be automatically disabled when running under Valgrind. This |
| 1611 | gives improved memory leak detection when running under Valgrind, while taking |
| 1612 | advantage of pymalloc at other times (:issue:`2422`). |
| 1613 | |
| 1614 | * Removed the "O?" format from the *PyArg_Parse* functions. The format is no |
| 1615 | longer used and it had never been documented (:issue:`8837`). |
| 1616 | |
| 1617 | There were a number of other small changes to the C-API. See the |
| 1618 | :file:`Misc/NEWS` file for a complete list. |
Skip Montanaro | 961aaf5 | 2010-10-17 22:22:24 +0000 | [diff] [blame] | 1619 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1620 | |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 1621 | Porting to Python 3.2 |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1622 | ===================== |
| 1623 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1624 | This section lists previously described changes and other bugfixes that may |
| 1625 | require changes to your code: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1626 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1627 | * The :mod:`configparser` module has a number of clean-ups. The major change is |
| 1628 | to replace the old :class:`ConfigParser` class with long-standing preferred |
| 1629 | alternative :class:`SafeConfigParser`. In addition there are a number of |
| 1630 | smaller incompatibilites: |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1631 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1632 | * The interpolation syntax is now validated on |
| 1633 | :meth:`~configparser.ConfigParser.get` and |
| 1634 | :meth:`~configparser.ConfigParser.set` operations. In the default |
| 1635 | interpolation scheme, only two tokens with percent signs are valid: ``%(name)s`` |
| 1636 | and ``%%``, the latter being an escaped percent sign. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1637 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1638 | * The :meth:`~configparser.ConfigParser.set` and |
| 1639 | :meth:`~configparser.ConfigParser.add_section` methods now verify that |
| 1640 | values are actual strings. Formerly, unsupported types could be introduced |
| 1641 | unintentionally. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1642 | |
Raymond Hettinger | 2b8861f | 2010-12-18 11:20:52 +0000 | [diff] [blame] | 1643 | * Duplicate sections or options from a single source now raise either |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1644 | :exc:`~configparser.DuplicateSectionError` or |
| 1645 | :exc:`~configparser.DuplicateOptionError`. Formerly, duplicates would |
| 1646 | silently overwrite a previous entry. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1647 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1648 | * Inline comments are now disabled by default so now the **;** character |
| 1649 | can be safely used in values. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1650 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1651 | * Comments now can be indented. Consequently, for **;** or **#** to appear at |
| 1652 | the start of a line in multiline values, it has to be interpolated. This |
Raymond Hettinger | 2b8861f | 2010-12-18 11:20:52 +0000 | [diff] [blame] | 1653 | keeps comment prefix characters in values from being mistaken as comments. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1654 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1655 | * ``""`` is now a valid value and is no longer automatically converted to an |
| 1656 | empty string. For empty strings, use ``"option ="`` in a line. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1657 | |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 1658 | * The :mod:`nntplib` module was reworked extensively, meaning that its APIs |
| 1659 | are often incompatible with the 3.1 APIs. |
| 1660 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1661 | * :class:`bytearray` objects can no longer be used as filenames; instead, |
| 1662 | they should be converted to :class:`bytes`. |
Victor Stinner | dcb2403 | 2010-04-22 12:08:36 +0000 | [diff] [blame] | 1663 | |
Victor Stinner | 25e8ec4 | 2010-06-25 00:02:38 +0000 | [diff] [blame] | 1664 | * PyArg_Parse*() functions: |
Victor Stinner | 3dcb5ac | 2010-06-08 22:54:19 +0000 | [diff] [blame] | 1665 | |
Victor Stinner | 25e8ec4 | 2010-06-25 00:02:38 +0000 | [diff] [blame] | 1666 | * "t#" format has been removed: use "s#" or "s*" instead |
| 1667 | * "w" and "w#" formats has been removed: use "w*" instead |
| 1668 | |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 1669 | * The :c:type:`PyCObject` type, deprecated in 3.1, has been removed. To wrap |
| 1670 | opaque C pointers in Python objects, the :c:type:`PyCapsule` API should be used |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 1671 | 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] | 1672 | information and a less complicated signature for calling a destructor. |
Victor Stinner | 0cbec57 | 2010-09-12 20:32:57 +0000 | [diff] [blame] | 1673 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1674 | * The :func:`sys.setfilesystemencoding` function was removed because |
| 1675 | it had a flawed design. |
Raymond Hettinger | 3fcf002 | 2010-12-08 01:13:53 +0000 | [diff] [blame] | 1676 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1677 | * The :func:`random.seed` function and method now salt string seeds with an |
| 1678 | sha512 hash function. To access the previous version of *seed* in order to |
| 1679 | reproduce Python 3.1 sequences, set the *version* argument to *1*, |
| 1680 | ``random.seed(s, version=1)``. |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1681 | |
Raymond Hettinger | 522cc0a | 2010-12-10 01:19:15 +0000 | [diff] [blame] | 1682 | * The previously deprecated :func:`string.maketrans` function has been removed |
| 1683 | in favor of the static methods, :meth:`bytes.maketrans` and |
| 1684 | :meth:`bytearray.maketrans`. This change solves the confusion around which |
| 1685 | types were supported by the :mod:`string` module. Now, :class:`str`, |
| 1686 | :class:`bytes`, and :class:`bytearray` each have their own **maketrans** and |
| 1687 | **translate** methods with intermediate translation tables of the appropriate |
| 1688 | type. |
| 1689 | |
| 1690 | (Contributed by Georg Brandl; :issue:`5675`.) |
| 1691 | |
| 1692 | * The previously deprecated :func:`contextlib.nested` function has been removed |
| 1693 | in favor of a plain :keyword:`with` statement which can accept multiple |
| 1694 | context managers. The latter technique is faster (because it is built-in), |
| 1695 | and it does a better job finalizing multiple context managers when one of them |
| 1696 | raises an exception:: |
| 1697 | |
| 1698 | >>> with open('mylog.txt') as infile, open('a.out', 'w') as outfile: |
| 1699 | ... for line in infile: |
| 1700 | ... if '<critical>' in line: |
| 1701 | ... outfile.write(line) |
| 1702 | |
| 1703 | (Contributed by Georg Brandl and Mattias Brändström; |
| 1704 | `appspot issue 53094 <http://codereview.appspot.com/53094>`_.) |