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 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 58 | |
Martin v. Löwis | 932e49e | 2010-12-04 13:49:32 +0000 | [diff] [blame] | 59 | PEP 384: Defining a Stable ABI |
Martin v. Löwis | 4d0d471 | 2010-12-03 20:14:31 +0000 | [diff] [blame] | 60 | ============================== |
| 61 | |
| 62 | In the past, extension modules built for one Python version were often |
| 63 | not usable with other Python versions. Particularly on Windows, every |
| 64 | feature release of Python required rebuilding all extension modules that |
| 65 | one wanted to use. This requirement was the result of the free access to |
| 66 | Python interpreter internals that extension modules could use. |
| 67 | |
| 68 | With Python 3.2, an alternative approach becomes available: extension |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 69 | modules which restrict themselves to a limited API (by defining |
Martin v. Löwis | 4d0d471 | 2010-12-03 20:14:31 +0000 | [diff] [blame] | 70 | Py_LIMITED_API) cannot use many of the internals, but are constrained |
| 71 | to a set of API functions that are promised to be stable for several |
| 72 | releases. As a consequence, extension modules built for 3.2 in that |
| 73 | mode will also work with 3.3, 3.4, and so on. Extension modules that |
| 74 | make use of details of memory structures can still be built, but will |
| 75 | need to be recompiled for every feature release. |
| 76 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 77 | .. seealso:: |
| 78 | |
Georg Brandl | 65b2eb9 | 2010-12-05 11:42:38 +0000 | [diff] [blame] | 79 | :pep:`384` - Defining a Stable ABI |
Raymond Hettinger | 2c1ecc3 | 2010-12-07 09:55:02 +0000 | [diff] [blame] | 80 | PEP written by Martin von Löwis. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 81 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 82 | |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 83 | PEP 389: Argparse Command Line Parsing Module |
| 84 | ============================================= |
| 85 | |
| 86 | A new module for command line parsing, :mod:`argparse`, was introduced to |
| 87 | overcome the limitations of :mod:`optparse` which did not provide support for |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 88 | positional arguments (not just options), subcommands, required options and other |
Raymond Hettinger | 413abbc | 2010-12-05 07:06:47 +0000 | [diff] [blame] | 89 | common patterns of specifying and validating options. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 90 | |
| 91 | 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] | 92 | third-party module. Being more fully featured than its predecessor, the |
| 93 | :mod:`argparse` module is now the preferred module for command-line processing. |
| 94 | The older module is still being kept available because of the substantial amount |
| 95 | of legacy code that depends on it. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 96 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 97 | Here's an annotated example parser showing features like limiting results to a |
| 98 | 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] | 99 | or more positional arguments is present, and making a required option:: |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 100 | |
| 101 | import argparse |
| 102 | parser = argparse.ArgumentParser( |
| 103 | description = 'Manage servers', # main description for help |
| 104 | epilog = 'Tested on Solaris and Linux') # displayed after help |
| 105 | parser.add_argument('action', # argument name |
Raymond Hettinger | 9297709 | 2011-01-16 09:18:59 +0000 | [diff] [blame] | 106 | choices = ['deploy', 'start', 'stop'], # three allowed values |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 107 | help = 'action on each target') # help msg |
| 108 | parser.add_argument('targets', |
| 109 | metavar = 'HOSTNAME', # var name used in help msg |
Raymond Hettinger | 9297709 | 2011-01-16 09:18:59 +0000 | [diff] [blame] | 110 | nargs = '+', # require one or more targets |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 111 | help = 'url for target machines') # help msg explanation |
| 112 | parser.add_argument('-u', '--user', # -u or --user option |
Georg Brandl | 52a43b5 | 2011-01-16 09:11:45 +0000 | [diff] [blame] | 113 | required = True, # make it a required argument |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 114 | help = 'login as user') |
| 115 | |
| 116 | Example of calling the parser on a command string:: |
| 117 | |
| 118 | >>> cmd = 'deploy sneezy.example.com sleepy.example.com -u skycaptain' |
| 119 | >>> result = parser.parse_args(cmd.split()) |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 120 | >>> result.action |
| 121 | 'deploy' |
| 122 | >>> result.targets |
| 123 | ['sneezy.example.com', 'sleepy.example.com'] |
| 124 | >>> result.user |
| 125 | 'skycaptain' |
| 126 | |
| 127 | Example of the parser's automatically generated help:: |
| 128 | |
| 129 | >>> parser.parse_args('-h'.split()) |
| 130 | |
Raymond Hettinger | 3fcf002 | 2010-12-08 01:13:53 +0000 | [diff] [blame] | 131 | usage: manage_cloud.py [-h] -u USER |
| 132 | {deploy,start,stop} HOSTNAME [HOSTNAME ...] |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 133 | |
| 134 | Manage servers |
| 135 | |
| 136 | positional arguments: |
| 137 | {deploy,start,stop} action on each target |
| 138 | HOSTNAME url for target machines |
| 139 | |
| 140 | optional arguments: |
| 141 | -h, --help show this help message and exit |
| 142 | -u USER, --user USER login as user |
| 143 | |
| 144 | Tested on Solaris and Linux |
| 145 | |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 146 | An especially nice :mod:`argparse` feature is the ability to define subparsers, |
| 147 | each with their own argument patterns and help displays:: |
| 148 | |
| 149 | import argparse |
| 150 | parser = argparse.ArgumentParser(prog='HELM') |
| 151 | subparsers = parser.add_subparsers() |
| 152 | |
| 153 | parser_l = subparsers.add_parser('launch', help='Launch Control') # first subgroup |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 154 | parser_l.add_argument('-m', '--missiles', action='store_true') |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 155 | parser_l.add_argument('-t', '--torpedos', action='store_true') |
| 156 | |
Raymond Hettinger | 3094ed8 | 2010-12-18 09:41:32 +0000 | [diff] [blame] | 157 | parser_m = subparsers.add_parser('move', help='Move Vessel', # second subgroup |
| 158 | aliases=('steer', 'turn')) # equivalent names |
Raymond Hettinger | b1ff402 | 2010-12-08 11:19:45 +0000 | [diff] [blame] | 159 | parser_m.add_argument('-c', '--course', type=int, required=True) |
| 160 | parser_m.add_argument('-s', '--speed', type=int, default=0) |
| 161 | |
| 162 | $ ./helm.py --help # top level help (launch and move) |
| 163 | $ ./helm.py launch --help # help for launch options |
| 164 | $ ./helm.py launch --missiles # set missiles=True and torpedos=False |
Raymond Hettinger | 3094ed8 | 2010-12-18 09:41:32 +0000 | [diff] [blame] | 165 | $ ./helm.py steer --course 180 --speed 5 # set movement parameters |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 166 | |
| 167 | .. seealso:: |
| 168 | |
| 169 | :pep:`389` - New Command Line Parsing Module |
| 170 | PEP written by Steven Bethard. |
| 171 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 172 | :ref:`upgrading-optparse-code` for details on the differences from |
| 173 | :mod:`optparse`. |
| 174 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 175 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 176 | PEP 391: Dictionary Based Configuration for Logging |
| 177 | ==================================================== |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 178 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 179 | The :mod:`logging` module provided two kinds of configuration, one style with |
| 180 | function calls for each option or another style driven by an external file saved |
| 181 | in a :mod:`ConfigParser` format. Those options did not provide the flexibility |
Georg Brandl | 9e75cad | 2010-09-06 06:45:47 +0000 | [diff] [blame] | 182 | to create configurations from JSON or YAML files, nor did they support |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 183 | incremental configuration, which is needed for specifying logger options from a |
| 184 | command line. |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 185 | |
| 186 | To support a more flexible style, the module now offers |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 187 | :func:`logging.config.dictConfig` for specifying logging configuration with |
| 188 | plain Python dictionaries. The configuration options include formatters, |
| 189 | handlers, filters, and loggers. Here's a working example of a configuration |
| 190 | dictionary:: |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 191 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 192 | {"version": 1, |
| 193 | "formatters": {"brief": {"format": "%(levelname)-8s: %(name)-15s: %(message)s"}, |
| 194 | "full": {"format": "%(asctime)s %(name)-15s %(levelname)-8s %(message)s"}, |
| 195 | }, |
| 196 | "handlers": {"console": { |
| 197 | "class": "logging.StreamHandler", |
| 198 | "formatter": "brief", |
| 199 | "level": "INFO", |
| 200 | "stream": "ext://sys.stdout"}, |
| 201 | "console_priority": { |
| 202 | "class": "logging.StreamHandler", |
| 203 | "formatter": "full", |
| 204 | "level": "ERROR", |
| 205 | "stream": "ext://sys.stderr"}, |
| 206 | }, |
| 207 | "root": {"level": "DEBUG", "handlers": ["console", "console_priority"]}} |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 208 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 209 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 210 | If that dictionary is stored in a file called :file:`conf.json`, it can be |
| 211 | loaded and called with code like this:: |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 212 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 213 | >>> import json, logging.config |
| 214 | >>> with open('conf.json', 'rb') as f: |
| 215 | conf = json.load(f) |
| 216 | >>> logging.config.dictConfig(conf) |
| 217 | >>> logging.info("Transaction completed normally") |
| 218 | >>> logging.critical("Abnormal termination") |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 219 | |
Raymond Hettinger | ef2335c | 2010-09-05 08:35:38 +0000 | [diff] [blame] | 220 | .. seealso:: |
| 221 | |
| 222 | :pep:`391` - Dictionary Based Configuration for Logging |
| 223 | PEP written by Vinay Sajip. |
| 224 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 225 | |
Georg Brandl | 97b20da | 2010-11-16 15:15:29 +0000 | [diff] [blame] | 226 | PEP 3148: The ``concurrent.futures`` module |
| 227 | ============================================ |
| 228 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 229 | Code for creating and managing concurrency is being collected in a new toplevel |
| 230 | namespace, *concurrent*. Its first member is a *futures* package which provides |
| 231 | a uniform high level interface for managing threads and processes. |
| 232 | |
| 233 | The design for :mod:`concurrent.futures` was inspired by |
| 234 | *java.util.concurrent.package*. In that model, a running call and its result |
| 235 | are represented by a :class:`~concurrent.futures.Future` object which abstracts |
| 236 | features common to threads, processes, and remote procedure calls. That object |
| 237 | supports status checks (running or done), timeouts, cancellations, adding |
Raymond Hettinger | 24a0941 | 2010-12-08 06:50:02 +0000 | [diff] [blame] | 238 | callbacks, and access to results or exceptions. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 239 | |
| 240 | The primary offering of the new module is a pair of executor classes for |
| 241 | launching and managing calls. The goal of the executors is to make it easier to |
| 242 | use existing tools for making parallel calls. They save the effort needed to |
| 243 | setup a pool of resources, launch the calls, create a results queue, add |
| 244 | 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] | 245 | procedure calls. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 246 | |
| 247 | Ideally, each application should share a single executor across multiple |
| 248 | components so that process and thread limits can be centrally managed. This |
| 249 | solves the design challenge that arises when each component has its own |
| 250 | competing strategy for resource management. |
| 251 | |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 252 | Both classes share a common interface with three methods: |
| 253 | :meth:`~concurrent.futures.Executor.submit` for scheduling a callable and |
| 254 | returning a :class:`~concurrent.futures.Future` object; |
| 255 | :meth:`~concurrent.futures.Executor.map` for scheduling many asynchronous calls |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 256 | at a time, and :meth:`~concurrent.futures.Executor.shutdown` for freeing |
| 257 | resources. The class is a :term:`context manager` and can be used within a |
| 258 | :keyword:`with` statement to assure that resources are automatically released |
| 259 | when currently pending futures are done executing. |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 260 | |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 261 | A simple of example of :class:`~concurrent.futures.ThreadPoolExecutor` is a |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 262 | launch of four parallel threads for copying files:: |
Raymond Hettinger | b105519 | 2010-12-08 06:42:41 +0000 | [diff] [blame] | 263 | |
| 264 | import shutil |
| 265 | with ThreadPoolExecutor(max_workers=4) as e: |
| 266 | e.submit(shutil.copy, 'src1.txt', 'dest1.txt') |
| 267 | e.submit(shutil.copy, 'src2.txt', 'dest2.txt') |
| 268 | e.submit(shutil.copy, 'src3.txt', 'dest3.txt') |
| 269 | e.submit(shutil.copy, 'src3.txt', 'dest4.txt') |
| 270 | |
Raymond Hettinger | 6f04adc | 2010-12-04 22:56:25 +0000 | [diff] [blame] | 271 | .. seealso:: |
| 272 | |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 273 | :pep:`3148` - Futures -- Execute Computations Asynchronously |
Andrew M. Kuchling | 42877fe | 2010-12-15 02:37:01 +0000 | [diff] [blame] | 274 | PEP written by Brian Quinlan. |
Georg Brandl | 97b20da | 2010-11-16 15:15:29 +0000 | [diff] [blame] | 275 | |
Raymond Hettinger | 83d8079 | 2010-12-08 06:48:33 +0000 | [diff] [blame] | 276 | :ref:`Code for Threaded Parallel URL reads<threadpoolexecutor-example>`, an |
| 277 | example using threads to fetch multiple web pages in parallel. |
| 278 | |
| 279 | :ref:`Code for computing prime numbers in |
| 280 | parallel<processpoolexecutor-example>`, an example demonstrating |
| 281 | :class:`~concurrent.futures.ProcessPoolExecutor`. |
| 282 | |
| 283 | |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 284 | PEP 3147: PYC Repository Directories |
| 285 | ===================================== |
| 286 | |
David Malcolm | 778645a | 2010-12-07 00:32:04 +0000 | [diff] [blame] | 287 | Python's scheme for caching bytecode in *.pyc* files did not work well in |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 288 | environments with multiple Python interpreters. If one interpreter encountered |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 289 | a cached file created by another interpreter, it would recompile the source and |
| 290 | overwrite the cached file, thus losing the benefits of caching. |
| 291 | |
| 292 | 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] | 293 | commonplace for Linux distributions to ship with multiple versions of Python. |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 294 | These conflicts also arise with CPython alternatives such as Unladen Swallow. |
| 295 | |
| 296 | 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] | 297 | distinct filenames for each interpreter. Instead of Python 3.2 and Python 3.3 and |
| 298 | 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] | 299 | look for "mymodule.cpython-32.pyc", "mymodule.cpython-33.pyc", and |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 300 | "mymodule.unladen10.pyc". And to prevent all of these new files from |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 301 | cluttering source directories, the *pyc* files are now collected in a |
| 302 | "__pycache__" directory stored under the package directory. |
| 303 | |
| 304 | Aside from the filenames and target directories, the new scheme has a few |
| 305 | aspects that are visible to the programmer: |
| 306 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 307 | * Imported modules now have a :attr:`__cached__` attribute which stores the name |
| 308 | of the actual file that was imported: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 309 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 310 | >>> import collections |
| 311 | >>> collections.__cached__ |
| 312 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 313 | |
| 314 | * 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] | 315 | module: |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 316 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 317 | >>> import imp |
| 318 | >>> imp.get_tag() |
| 319 | 'cpython-32' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 320 | |
| 321 | * Scripts that try to deduce source filename from the imported file now need to |
| 322 | be smarter. It is no longer sufficient to simply strip the "c" from a ".pyc" |
| 323 | filename. Instead, use the new functions in the :mod:`imp` module: |
| 324 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 325 | >>> imp.source_from_cache('c:/py32/lib/__pycache__/collections.cpython-32.pyc') |
| 326 | 'c:/py32/lib/collections.py' |
| 327 | >>> imp.cache_from_source('c:/py32/lib/collections.py') |
| 328 | 'c:/py32/lib/__pycache__/collections.cpython-32.pyc' |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 329 | |
| 330 | * The :mod:`py_compile` and :mod:`compileall` modules have been updated to |
| 331 | reflect the new naming convention and target directory. |
| 332 | |
Raymond Hettinger | 1dcc84e | 2011-01-17 21:55:40 +0000 | [diff] [blame] | 333 | * The :mod:`importlib.abc` module has been updated with new :term:`abstract base |
Raymond Hettinger | 66352d2 | 2011-01-17 22:33:11 +0000 | [diff] [blame] | 334 | classes <abstract base class>` for the loading bytecode files. The obsolete |
| 335 | ABCs, :class:`~importlib.abc.PyLoader` and |
Raymond Hettinger | 1dcc84e | 2011-01-17 21:55:40 +0000 | [diff] [blame] | 336 | :class:`~importlib.abc.PyPycLoader`, have been deprecated (instructions on how |
Raymond Hettinger | 66352d2 | 2011-01-17 22:33:11 +0000 | [diff] [blame] | 337 | to stay Python 3.1 compatible are included with the documentation). |
Brett Cannon | 83a682d | 2011-01-16 21:02:09 +0000 | [diff] [blame] | 338 | |
Raymond Hettinger | f95b199 | 2010-09-04 23:53:24 +0000 | [diff] [blame] | 339 | .. seealso:: |
| 340 | |
| 341 | :pep:`3147` - PYC Repository Directories |
| 342 | PEP written by Barry Warsaw. |
| 343 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 344 | |
Georg Brandl | 3ad4675 | 2010-12-05 07:59:29 +0000 | [diff] [blame] | 345 | PEP 3149: ABI Version Tagged .so Files |
| 346 | ====================================== |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 347 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 348 | The PYC repository directory allows multiple bytecode cache files to be |
| 349 | co-located. This PEP implements a similar mechanism for shared object files by |
| 350 | giving them a common directory and distinct names for each version. |
Georg Brandl | f11c6c4 | 2010-09-03 22:20:58 +0000 | [diff] [blame] | 351 | |
Raymond Hettinger | ebea6fa | 2010-09-05 00:27:25 +0000 | [diff] [blame] | 352 | The common directory is "pyshared" and the file names are made distinct by |
| 353 | identifying the Python implementation (such as CPython, PyPy, Jython, etc.), the |
| 354 | 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] | 355 | 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] | 356 | you may see these files when the distribution package is installed:: |
| 357 | |
| 358 | /usr/share/pyshared/foo.cpython-32m.so |
| 359 | /usr/share/pyshared/foo.cpython-33md.so |
| 360 | |
| 361 | In Python itself, the tags are accessible from functions in the :mod:`sysconfig` |
| 362 | module:: |
| 363 | |
| 364 | >>> import sysconfig |
| 365 | >>> sysconfig.get_config_var('SOABI') # find the version tag |
| 366 | 'cpython-32mu' |
| 367 | >>> sysconfig.get_config_var('SO') # find the full filename extension |
| 368 | 'cpython-32mu.so' |
| 369 | |
| 370 | .. seealso:: |
| 371 | |
| 372 | :pep:`3149` - ABI Version Tagged .so Files |
| 373 | PEP written by Barry Warsaw. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 374 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 375 | |
Raymond Hettinger | 3df4621 | 2011-01-06 02:01:26 +0000 | [diff] [blame] | 376 | PEP 3333: Python Web Server Gateway Interface v1.0.1 |
| 377 | ===================================================== |
| 378 | |
| 379 | This informational PEP clarifies how bytes/text issues are to be handled by the |
| 380 | WGSI protocol. The challenge is that string handling in Python 3 is most |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 381 | conveniently handled with the :class:`str` type even though the HTTP protocol |
Raymond Hettinger | 3df4621 | 2011-01-06 02:01:26 +0000 | [diff] [blame] | 382 | is itself bytes oriented. |
| 383 | |
| 384 | The PEP differentiates so-called *native strings* that are used for |
| 385 | request/response headers and metadata versus *byte strings* which are used for |
| 386 | the bodies of requests and responses. |
| 387 | |
| 388 | The *native strings* are always of type :class:`str` but are restricted to code |
Georg Brandl | 52a43b5 | 2011-01-16 09:11:45 +0000 | [diff] [blame] | 389 | points between *U+0000* through *U+00FF* which are translatable to bytes using |
Raymond Hettinger | 32e8fea | 2011-01-07 21:04:30 +0000 | [diff] [blame] | 390 | *Latin-1* encoding. These strings are used for the keys and values in the |
| 391 | environ dictionary and for response headers and statuses in the |
| 392 | :func:`start_response` function. They must follow :rfc:`2616` with respect to |
Raymond Hettinger | 3df4621 | 2011-01-06 02:01:26 +0000 | [diff] [blame] | 393 | encoding. That is, they must either be *ISO-8859-1* characters or use |
| 394 | :rfc:`2047` MIME encoding. |
| 395 | |
Raymond Hettinger | 32e8fea | 2011-01-07 21:04:30 +0000 | [diff] [blame] | 396 | For developers porting WSGI applications from Python 2, here are the salient |
| 397 | points: |
| 398 | |
| 399 | * If the app already used strings for headers in Python 2, no change is needed. |
| 400 | |
| 401 | * If instead, the app encoded output headers or decoded input headers, then the |
| 402 | headers will need to be re-encoded to Latin-1. For example, an output header |
| 403 | encoded in utf-8 was using ``h.encode('utf-8')`` now needs to convert from |
| 404 | bytes to native strings using ``h.encode('utf-8').decode('latin-1')``. |
| 405 | |
| 406 | * Values yielded by an application or sent using the :meth:`write` method |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 407 | must be byte strings. The :func:`start_response` function and environ |
| 408 | must use native strings. The two cannot be mixed. |
Raymond Hettinger | 32e8fea | 2011-01-07 21:04:30 +0000 | [diff] [blame] | 409 | |
| 410 | For server implementers writing CGI-to-WSGI pathways or other CGI-style |
| 411 | protocols, the users must to be able access the environment using native strings |
| 412 | eventhough the underlying platform may have a different convention. To bridge |
| 413 | this gap, the :mod:`wsgiref` module has a new function, |
| 414 | :func:`wsgiref.handlers.read_environ` for transcoding CGI variables from |
| 415 | :attr:`os.environ` into native strings and returning a new dictionary. |
Raymond Hettinger | 3df4621 | 2011-01-06 02:01:26 +0000 | [diff] [blame] | 416 | |
| 417 | .. seealso:: |
| 418 | |
| 419 | :pep:`3333` - Python Web Server Gateway Interface v1.0.1 |
| 420 | PEP written by Phillip Eby. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 421 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 422 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 423 | Other Language Changes |
| 424 | ====================== |
| 425 | |
| 426 | Some smaller changes made to the core Python language are: |
| 427 | |
Raymond Hettinger | e5e1a98 | 2010-12-05 08:35:21 +0000 | [diff] [blame] | 428 | * String formatting for :func:`format` and :meth:`str.format` gained new |
| 429 | capabilities for the format character **#**. Previously, for integers in |
| 430 | binary, octal, or hexadecimal, it caused the output to be prefixed with '0b', |
| 431 | '0o', or '0x' respectively. Now it can also handle floats, complex, and |
| 432 | Decimal, causing the output to always have a decimal point even when no digits |
| 433 | follow it. |
Raymond Hettinger | e5e728b | 2010-12-05 06:35:16 +0000 | [diff] [blame] | 434 | |
| 435 | >>> format(20, '#o') |
| 436 | '0o24' |
| 437 | >>> format(12.34, '#5.0f') |
| 438 | ' 12.' |
| 439 | |
| 440 | (Suggested by Mark Dickinson and implemented by Eric Smith in :issue:`7094`.) |
Raymond Hettinger | 43b5a85 | 2010-12-05 04:04:21 +0000 | [diff] [blame] | 441 | |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 442 | * The interpreter can now be started with a quiet option, ``-q``, to suppress |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 443 | the copyright and version information from being displayed in the interactive |
| 444 | mode. The option can be introspected using the :attr:`sys.flags` attribute:: |
Raymond Hettinger | 7d96771 | 2011-01-05 20:24:08 +0000 | [diff] [blame] | 445 | |
| 446 | $ python -q |
| 447 | >>> sys.flags |
| 448 | sys.flags(debug=0, division_warning=0, inspect=0, interactive=0, |
| 449 | optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, |
| 450 | ignore_environment=0, verbose=0, bytes_warning=0, quiet=1) |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 451 | |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 452 | (Contributed by Marcin Wojdyr in :issue:`1772833`). |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 453 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 454 | * The :func:`hasattr` function works by calling :func:`getattr` and detecting |
| 455 | whether an exception is raised. This technique allows it to detect methods |
| 456 | created dynamically by :meth:`__getattr__` or :meth:`__getattribute__` which |
Raymond Hettinger | 90a4b31 | 2011-01-06 02:08:30 +0000 | [diff] [blame] | 457 | would otherwise be absent from the class dictionary. Formerly, *hasattr* |
| 458 | would catch any exception, possibly masking genuine errors. Now, *hasattr* |
| 459 | has been tightened to only catch :exc:`AttributeError` and let other |
| 460 | exceptions pass through. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 461 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 462 | (Discovered by Yury Selivanov and fixed by Benjamin Peterson; :issue:`9666`.) |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 463 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 464 | * 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] | 465 | :func:`repr`. Previously, the :func:`str` form was shorter but that just |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 466 | caused confusion and is no longer needed now that the shortest possible |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 467 | :func:`repr` is displayed by default: |
Raymond Hettinger | bb734c6 | 2010-09-05 05:56:44 +0000 | [diff] [blame] | 468 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 469 | >>> repr(math.pi) |
| 470 | '3.141592653589793' |
| 471 | >>> str(math.pi) |
| 472 | '3.141592653589793' |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 473 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 474 | (Proposed and implemented by Mark Dickinson; :issue:`9337`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 475 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 476 | * :class:`memoryview` objects now have a :meth:`~memoryview.release()` method |
| 477 | and they also now support the context manager protocol. This allows timely |
| 478 | release of any resources that were acquired when requesting a buffer from the |
| 479 | original object. |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 480 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 481 | >>> with memoryview(b'abcdefgh') as v: |
| 482 | ... print(v.tolist()) |
| 483 | ... |
| 484 | [97, 98, 99, 100, 101, 102, 103, 104] |
| 485 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 486 | (Added by Antoine Pitrou; :issue:`9757`.) |
| 487 | |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 488 | * Previously it was illegal to delete a name from the local namespace if it |
| 489 | occurs as a free variable in a nested block:: |
| 490 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 491 | def outer(x): |
| 492 | def inner(): |
| 493 | return x |
| 494 | inner() |
| 495 | del x |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 496 | |
| 497 | This is now allowed. Remember that the target of an :keyword:`except` clause |
| 498 | is cleared, so this code which used to work with Python 2.6, raised a |
| 499 | :exc:`SyntaxError` with Python 3.1 and now works again:: |
| 500 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 501 | def f(): |
| 502 | def print_error(): |
| 503 | print(e) |
| 504 | try: |
| 505 | something |
| 506 | except Exception as e: |
| 507 | print_error() |
| 508 | # implicit "del e" here |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 509 | |
| 510 | (See :issue:`4617`.) |
| 511 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 512 | * The internal :c:type:`structsequence` tool now creates subclasses of tuple. |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 513 | This means that C structures like those returned by :func:`os.stat`, |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 514 | :func:`time.gmtime`, and :func:`sys.version_info` now work like a |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 515 | :term:`named tuple` and now work with functions and methods that |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 516 | expect a tuple as an argument. The is a big step forward in making the C |
| 517 | structures as flexible as their pure Python counterparts. |
| 518 | |
| 519 | (Suggested by Arfrever Frehtes Taifersar Arahesis and implemented |
| 520 | by Benjamin Peterson in :issue:`8413`.) |
| 521 | |
Michael Foord | 5e9b14c | 2010-12-22 10:39:04 +0000 | [diff] [blame] | 522 | * Warnings are now easier to control. A :envvar:`PYTHONWARNINGS` environment |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 523 | variable is now available as an alternative to using ``-W`` at the command |
| 524 | line. |
| 525 | |
| 526 | (Suggested by Barry Warsaw and implemented by Philip Jenvey in :issue:`7301`.) |
| 527 | |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 528 | * A new warning category, :exc:`ResourceWarning`, has been added. It is |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 529 | emitted when potential issues with resource consumption or cleanup |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 530 | are detected. It is silenced by default in normal release builds, but |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 531 | can be enabled through the means provided by the :mod:`warnings` |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 532 | module, or on the command line. |
| 533 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 534 | A :exc:`ResourceWarning` is issued at interpreter shutdown if the |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 535 | :data:`gc.garbage` list isn't empty. This is meant to make the programmer |
| 536 | aware that their code contains object finalization issues. |
| 537 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 538 | 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] | 539 | without having been explicitly closed. While the deallocator for such |
| 540 | object ensures it closes the underlying operating system resource |
| 541 | (usually, a file descriptor), the delay in deallocating the object could |
| 542 | produce various issues, especially under Windows. Here is an example |
| 543 | of enabling the warning from the command line:: |
| 544 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 545 | $ python -q -Wdefault |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 546 | >>> f = open("foo", "wb") |
| 547 | >>> del f |
| 548 | __main__:1: ResourceWarning: unclosed file <_io.BufferedWriter name='foo'> |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 549 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 550 | (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] | 551 | |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 552 | * :class:`range` objects now support *index* and *count* methods. This is part |
| 553 | of an effort to make more objects fully implement the |
| 554 | :class:`collections.Sequence` :term:`abstract base class`. As a result, the |
| 555 | language will have a more uniform API. In addition, :class:`range` objects |
Raymond Hettinger | b965629 | 2011-01-16 18:22:06 +0000 | [diff] [blame] | 556 | now support slicing and negative indices, even with values larger than |
| 557 | :attr:`sys.maxsize`. This makes *range* more interoperable with lists:: |
Raymond Hettinger | 2ffa671 | 2010-12-08 10:18:21 +0000 | [diff] [blame] | 558 | |
| 559 | >>> range(0, 100, 2).count(10) |
| 560 | 1 |
| 561 | >>> range(0, 100, 2).index(10) |
| 562 | 5 |
| 563 | >>> range(0, 100, 2)[5] |
| 564 | 10 |
| 565 | >>> range(0, 100, 2)[0:5] |
| 566 | range(0, 10, 2) |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 567 | |
Raymond Hettinger | b965629 | 2011-01-16 18:22:06 +0000 | [diff] [blame] | 568 | (Contributed by Daniel Stutzbach in :issue:`9213`, by Alexander Belopolsky |
| 569 | in :issue:`2690`, and by Nick Coghlan in :issue:`10889`.) |
Nick Coghlan | 37ee850 | 2010-12-03 14:26:13 +0000 | [diff] [blame] | 570 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 571 | * The :func:`callable` builtin function from Py2.x was resurrected. It provides |
Raymond Hettinger | b87ba26 | 2010-12-06 04:31:40 +0000 | [diff] [blame] | 572 | 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] | 573 | expression like ``isinstance(x, collections.Callable)``: |
| 574 | |
| 575 | >>> callable(max) |
| 576 | True |
| 577 | >>> callable(20) |
| 578 | False |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 579 | |
| 580 | (See :issue:`10518`.) |
Amaury Forgeot d'Arc | ba117ef | 2010-09-10 21:39:53 +0000 | [diff] [blame] | 581 | |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 582 | * Python's import mechanism can now load module installed in directories with |
| 583 | non-ASCII characters in the path name. |
| 584 | |
| 585 | (Required extensive work by Victor Stinner in :issue:`9425`.) |
| 586 | |
| 587 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 588 | New, Improved, and Deprecated Modules |
| 589 | ===================================== |
| 590 | |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 591 | Python's standard library has undergone significant maintenance efforts and |
| 592 | quality improvements. |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 593 | |
| 594 | 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] | 595 | :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] | 596 | For the first time, there is correct handling of inputs with mixed encodings. |
| 597 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 598 | Throughout the standard library, there has been more careful attention to |
| 599 | encodings and text versus bytes issues. In particular, interactions with the |
| 600 | operating system are now better able to pass non-ASCII data using the Windows |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 601 | mcbs encoding, locale-aware encodings, or UTF-8. |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 602 | |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 603 | Another significant win is the addition of substantially better support for |
| 604 | *SSL* connections and security certificates. |
| 605 | |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 606 | In addition, more classes now implement a :term:`context manager` to support |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 607 | convenient and reliable resource clean-up using the :keyword:`with` statement. |
Raymond Hettinger | e434b3b | 2010-12-15 19:20:01 +0000 | [diff] [blame] | 608 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 609 | email |
| 610 | ----- |
| 611 | |
| 612 | The usability of the :mod:`email` package in Python 3 has been mostly fixed by |
| 613 | the extensive efforts of R. David Murray. The problem was that emails are |
| 614 | typically read and stored in the form of :class:`bytes` rather than :class:`str` |
| 615 | text, and they may contain multiple encodings within a single email. So, the |
| 616 | email package had to be extended to parse and generate email messages in bytes |
| 617 | format. |
| 618 | |
| 619 | * New functions :func:`~email.message_from_bytes` and |
| 620 | :func:`~email.message_from_binary_file`, and new classes |
| 621 | :class:`~email.parser.BytesFeedParser` and :class:`~email.parser.BytesParser` |
| 622 | allow binary message data to be parsed into model objects. |
| 623 | |
| 624 | * Given bytes input to the model, :meth:`~email.message.Message.get_payload` |
| 625 | will by default decode a message body that has a |
| 626 | :mailheader:`Content-Transfer-Encoding` of *8bit* using the charset |
| 627 | specified in the MIME headers and return the resulting string. |
| 628 | |
| 629 | * Given bytes input to the model, :class:`~email.generator.Generator` will |
| 630 | convert message bodies that have a :mailheader:`Content-Transfer-Encoding` of |
| 631 | *8bit* to instead have a *7bit* :mailheader:`Content-Transfer-Encoding`. |
Raymond Hettinger | c08ea61 | 2011-01-08 10:32:31 +0000 | [diff] [blame] | 632 | |
Raymond Hettinger | cf8a382 | 2011-01-11 21:20:20 +0000 | [diff] [blame] | 633 | Headers with unencoded non-ASCII bytes are deemed to be :rfc:`2047`\ -encoded |
| 634 | using the *unknown-8bit* character set. |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 635 | |
| 636 | * A new class :class:`~email.generator.BytesGenerator` produces bytes as output, |
| 637 | preserving any unchanged non-ASCII data that was present in the input used to |
| 638 | build the model, including message bodies with a |
| 639 | :mailheader:`Content-Transfer-Encoding` of *8bit*. |
| 640 | |
| 641 | * The :mod:`smtplib` :class:`~smtplib.SMTP` class now accepts a byte string |
| 642 | for the *msg* argument to the :meth:`~smtplib.SMTP.sendmail` method, |
| 643 | and a new method, :meth:`~smtplib.SMTP.send_message` accepts a |
| 644 | :class:`~email.message.Message` object and can optionally obtain the |
| 645 | *from_addr* and *to_addrs* addresses directly from the object. |
| 646 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 647 | (Proposed and implemented by R. David Murray, :issue:`4661` and :issue:`10321`.) |
| 648 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 649 | elementtree |
| 650 | ----------- |
| 651 | |
Georg Brandl | 5d53fdd | 2010-12-18 11:58:12 +0000 | [diff] [blame] | 652 | The :mod:`xml.etree.ElementTree` package and its :mod:`xml.etree.cElementTree` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 653 | counterpart have been updated to version 1.3. |
| 654 | |
| 655 | Several new and useful functions and methods have been added: |
| 656 | |
| 657 | * :func:`xml.etree.ElementTree.fromstringlist` which builds an XML document |
| 658 | from a sequence of fragments |
| 659 | * :func:`xml.etree.ElementTree.register_namespace` for registering a global |
| 660 | namespace prefix |
| 661 | * :func:`xml.etree.ElementTree.tostringlist` for string representation |
| 662 | including all sublists |
| 663 | * :meth:`xml.etree.ElementTree.Element.extend` for appending a sequence of zero |
| 664 | or more elements |
| 665 | * :meth:`xml.etree.ElementTree.Element.iterfind` searches an element and |
| 666 | subelements |
| 667 | * :meth:`xml.etree.ElementTree.Element.itertext` creates a text iterator over |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 668 | an element and its subelements |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 669 | * :meth:`xml.etree.ElementTree.TreeBuilder.end` closes the current element |
| 670 | * :meth:`xml.etree.ElementTree.TreeBuilder.doctype` handles a doctype |
| 671 | declaration |
| 672 | |
| 673 | Two methods have been deprecated: |
| 674 | |
| 675 | * :meth:`xml.etree.ElementTree.getchildren` use ``list(elem)`` instead. |
| 676 | * :meth:`xml.etree.ElementTree.getiterator` use ``Element.iter`` instead. |
| 677 | |
| 678 | For details of the update, see `Introducing ElementTree |
| 679 | <http://effbot.org/zone/elementtree-13-intro.htm>`_ on Fredrik Lundh's website. |
| 680 | |
Antoine Pitrou | 12de8ac | 2010-12-16 13:33:56 +0000 | [diff] [blame] | 681 | (Contributed by Florent Xicluna and Fredrik Lundh, :issue:`6472`.) |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 682 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 683 | functools |
| 684 | --------- |
| 685 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 686 | * The :mod:`functools` module includes a new decorator for caching function |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 687 | calls. :func:`functools.lru_cache` can save repeated queries to an external |
| 688 | resource whenever the results are expected to be the same. |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 689 | |
Raymond Hettinger | 86f9613 | 2010-08-06 23:23:49 +0000 | [diff] [blame] | 690 | For example, adding a caching decorator to a database query function can save |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 691 | database accesses for popular searches: |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 692 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 693 | >>> @functools.lru_cache(maxsize=300) |
| 694 | >>> def get_phone_number(name): |
| 695 | c = conn.cursor() |
| 696 | c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,)) |
| 697 | return c.fetchone()[0] |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 698 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 699 | >>> for name in user_requests: |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 700 | get_phone_number(name) # cached lookup |
Raymond Hettinger | 7496b41 | 2010-11-30 19:15:45 +0000 | [diff] [blame] | 701 | |
| 702 | To help with choosing an effective cache size, the wrapped function is |
| 703 | instrumented for tracking cache statistics: |
| 704 | |
Raymond Hettinger | 5e20bab | 2010-11-30 07:13:04 +0000 | [diff] [blame] | 705 | >>> get_phone_number.cache_info() |
Raymond Hettinger | 7496b41 | 2010-11-30 19:15:45 +0000 | [diff] [blame] | 706 | CacheInfo(hits=4805, misses=980, maxsize=300, currsize=300) |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 707 | |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 708 | 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] | 709 | cleared with: |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 710 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 711 | >>> get_phone_number.cache_clear() |
Raymond Hettinger | f309828 | 2010-08-15 03:30:45 +0000 | [diff] [blame] | 712 | |
Raymond Hettinger | 6e35394 | 2010-12-04 23:42:12 +0000 | [diff] [blame] | 713 | (Contributed by Raymond Hettinger and incorporating design ideas from |
Raymond Hettinger | b87ba26 | 2010-12-06 04:31:40 +0000 | [diff] [blame] | 714 | Jim Baker, Miki Tebeka, and Nick Coghlan.) |
Raymond Hettinger | aed05eb | 2010-08-02 01:43:41 +0000 | [diff] [blame] | 715 | |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 716 | * The :func:`functools.wraps` decorator now adds a :attr:`__wrapped__` attribute |
| 717 | pointing to the original callable function. This allows wrapped functions to |
| 718 | be introspected. It also copies :attr:`__annotations__` if defined. And now |
| 719 | it also gracefully skips over missing attributes such as :attr:`__doc__` which |
Raymond Hettinger | 5eb6390 | 2010-12-09 23:43:34 +0000 | [diff] [blame] | 720 | might not be defined for the wrapped callable. |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 721 | |
| 722 | (By Nick Coghlan and Terrence Cole; :issue:`9567`, :issue:`3445`, and |
| 723 | :issue:`8814`.) |
| 724 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 725 | * To help write classes with rich comparison methods, a new decorator |
| 726 | :func:`functools.total_ordering` will use a existing equality and inequality |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 727 | methods to fill in the remaining methods. |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 728 | |
| 729 | For example, supplying *__eq__* and *__lt__* will enable |
| 730 | :func:`~functools.total_ordering` to fill-in *__le__*, *__gt__* and *__ge__*:: |
| 731 | |
| 732 | @total_ordering |
| 733 | class Student: |
| 734 | def __eq__(self, other): |
| 735 | return ((self.lastname.lower(), self.firstname.lower()) == |
| 736 | (other.lastname.lower(), other.firstname.lower())) |
| 737 | def __lt__(self, other): |
| 738 | return ((self.lastname.lower(), self.firstname.lower()) < |
| 739 | (other.lastname.lower(), other.firstname.lower())) |
| 740 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 741 | With the *total_ordering* decorator, the remaining comparison methods |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 742 | are filled in automatically. |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 743 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 744 | (Contributed by Raymond Hettinger.) |
Raymond Hettinger | f35a34c | 2010-12-22 09:11:54 +0000 | [diff] [blame] | 745 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 746 | * 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] | 747 | function converts an old-style comparison function to |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 748 | modern :term:`key function`: |
| 749 | |
| 750 | >>> # locale-aware sort order |
| 751 | >>> sorted(iterable, key=cmp_to_key(locale.strcoll)) |
| 752 | |
| 753 | For sorting examples and a brief sorting tutorial, see the `Sorting HowTo |
| 754 | <http://wiki.python.org/moin/HowTo/Sorting/>`_ tutorial. |
| 755 | |
| 756 | (Contributed by Raymond Hettinger.) |
| 757 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 758 | itertools |
| 759 | --------- |
| 760 | |
Raymond Hettinger | 673ccf2 | 2010-12-07 09:37:11 +0000 | [diff] [blame] | 761 | * The :mod:`itertools` module has a new :func:`~itertools.accumulate` function |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 762 | modeled on APL's *scan* operator and on Numpy's *accumulate* function: |
Raymond Hettinger | 6e35394 | 2010-12-04 23:42:12 +0000 | [diff] [blame] | 763 | |
| 764 | >>> list(accumulate(8, 2, 50)) |
| 765 | [8, 10, 60] |
| 766 | |
| 767 | >>> prob_dist = [0.1, 0.4, 0.2, 0.3] |
| 768 | >>> list(accumulate(prob_dist)) # cumulative probability distribution |
| 769 | [0.1, 0.5, 0.7, 1.0] |
| 770 | |
| 771 | For an example using :func:`~itertools.accumulate`, see the :ref:`examples for |
| 772 | the random module <random-examples>`. |
| 773 | |
| 774 | (Contributed by Raymond Hettinger and incorporating design suggestions |
| 775 | from Mark Dickinson.) |
| 776 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 777 | collections |
| 778 | ----------- |
| 779 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 780 | * The :class:`collections.Counter` class now has two forms of in-place |
| 781 | subtraction, the existing *-=* operator for `saturating subtraction |
| 782 | <http://en.wikipedia.org/wiki/Saturation_arithmetic>`_ and the new |
| 783 | :meth:`~collections.Counter.subtract` method for regular subtraction. The |
| 784 | former is suitable for `multisets <http://en.wikipedia.org/wiki/Multiset>`_ |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 785 | 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] | 786 | that allow negative counts: |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 787 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 788 | >>> tally = Counter(dogs=5, cat=3) |
| 789 | >>> tally -= Counter(dogs=2, cats=8) # saturating subtraction |
| 790 | >>> tally |
| 791 | Counter({'dogs': 3}) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 792 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 793 | >>> tally = Counter(dogs=5, cats=3) |
| 794 | >>> tally.subtract(dogs=2, cats=8) # regular subtraction |
| 795 | >>> tally |
| 796 | Counter({'dogs': 3, 'cats': -5}) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 797 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 798 | (Contributed by Raymond Hettinger.) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 799 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 800 | * The :class:`collections.OrderedDict` class has a new method |
| 801 | :meth:`~collections.OrderedDict.move_to_end` which takes an existing key and |
| 802 | moves it to either the beginning or end of an ordered sequence. When the |
| 803 | dictionary sequence is being used as a queue, these operations correspond to |
| 804 | "move to the front of the line" or "move to the back of the line": |
| 805 | |
| 806 | >>> d = OrderedDict.fromkeys(['a', 'b', 'X', 'd', 'e']) |
| 807 | >>> list(d) |
| 808 | ['a', 'b', 'X', 'd', 'e'] |
| 809 | >>> d.move_to_end('X', last=True) |
| 810 | >>> list(d) |
| 811 | ['a', 'b', 'd', 'e', 'X'] |
| 812 | >>> d.move_to_end('X', last=False) |
| 813 | >>> list(d) |
| 814 | ['X', 'a', 'b', 'd', 'e'] |
| 815 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 816 | (Contributed by Raymond Hettinger.) |
| 817 | |
Raymond Hettinger | 7ec790d | 2011-01-18 00:19:30 +0000 | [diff] [blame^] | 818 | * The :class:`collections.deque` class grew two new methods |
| 819 | :meth:`~collections.deque.count` and :meth:`~collections.deque.reverse` that |
| 820 | make them more substitutable for :class:`list` objects: |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 821 | |
| 822 | >>> d = deque('simsalabim') |
| 823 | >>> d.count('s') |
| 824 | 2 |
| 825 | >>> d.reverse() |
| 826 | >>> d |
| 827 | deque(['m', 'i', 'b', 'a', 'l', 'a', 's', 'm', 'i', 's']) |
| 828 | |
| 829 | (Contributed by Raymond Hettinger.) |
| 830 | |
Raymond Hettinger | 5cee47f | 2011-01-11 19:59:46 +0000 | [diff] [blame] | 831 | threading |
| 832 | --------- |
| 833 | |
| 834 | The :mod:`threading` module has a new :class:`~threading.Barrier` |
| 835 | synchronization class for making multiple threads wait until all of them have |
| 836 | reached a common barrier point. Barriers are useful for making sure that a task |
| 837 | with multiple preconditions does not run until all of the predecessor tasks are |
| 838 | complete. |
| 839 | |
| 840 | Barriers can work with an arbitrary number of threads. This is a generalization |
| 841 | of a `Rendezvous <http://en.wikipedia.org/wiki/Synchronous_rendezvous>`_ which |
| 842 | is defined for only two threads. |
| 843 | |
Raymond Hettinger | 15b47c5 | 2011-01-17 21:05:07 +0000 | [diff] [blame] | 844 | Implemented as a two-phase cyclic barrier, :class:`~threading.Barrier` objects |
| 845 | are suitable for use in loops. The separate *filling* and *draining* phases |
| 846 | assure that all threads get released (drained) before any one them can loop back |
| 847 | and re-enter the barrier. The barrier fully resets after each cycle. |
Raymond Hettinger | 5cee47f | 2011-01-11 19:59:46 +0000 | [diff] [blame] | 848 | |
| 849 | If any of the predecessor tasks can hang or be delayed, a barrier can be created |
| 850 | with an optional *timeout* parameter. Then if the timeout period elapses before |
| 851 | all the predecessor tasks reach the barrier point, all waiting threads are |
| 852 | released and a :exc:`~threading.BrokenBarrierError` exception is raised. |
| 853 | |
| 854 | Example of using barriers:: |
| 855 | |
| 856 | def get_votes(site): |
| 857 | ballots = conduct_election(site) |
| 858 | all_polls_closed.wait() # do not count until all polls are closed |
Raymond Hettinger | 9767365 | 2011-01-11 21:13:26 +0000 | [diff] [blame] | 859 | totals = summarize(ballots) |
| 860 | publish(site, totals) |
Raymond Hettinger | 5cee47f | 2011-01-11 19:59:46 +0000 | [diff] [blame] | 861 | |
| 862 | all_polls_closed = Barrier(len(sites)) |
Raymond Hettinger | 3a8ae5f | 2011-01-11 20:51:45 +0000 | [diff] [blame] | 863 | for site in sites: |
Raymond Hettinger | 5cee47f | 2011-01-11 19:59:46 +0000 | [diff] [blame] | 864 | Thread(target=get_votes, args=(site,)).start() |
| 865 | |
| 866 | In this example, the barrier enforces a rule that votes cannot be counted at any |
| 867 | polling site until all polls are closed. Notice how a solution with a barrier |
| 868 | is similar to one with :meth:`threading.Thread.join`, but the threads stay alive |
| 869 | and continue to do work (summarizing ballots) after the barrier point is |
| 870 | crossed. |
| 871 | |
| 872 | See `Barrier Synchronization Patterns |
Raymond Hettinger | 3a8ae5f | 2011-01-11 20:51:45 +0000 | [diff] [blame] | 873 | <http://parlab.eecs.berkeley.edu/wiki/_media/patterns/paraplop_g1_3.pdf>`_ for |
| 874 | more examples of how barriers can be used in parallel computing. Also, there is |
| 875 | a simple but thorough explanation of barriers in `The Little Book of Semaphores |
| 876 | <http://greenteapress.com/semaphores/downey08semaphores.pdf>`_, *section 3.6*. |
Raymond Hettinger | 5cee47f | 2011-01-11 19:59:46 +0000 | [diff] [blame] | 877 | |
Raymond Hettinger | 3a8ae5f | 2011-01-11 20:51:45 +0000 | [diff] [blame] | 878 | (Contributed by Kristján Valur Jónsson with an API review by Jeffrey Yasskin in |
| 879 | :issue:`8777`.) |
Raymond Hettinger | 6655d11 | 2011-01-11 08:49:10 +0000 | [diff] [blame] | 880 | |
Raymond Hettinger | 9767365 | 2011-01-11 21:13:26 +0000 | [diff] [blame] | 881 | datetime and time |
| 882 | ----------------- |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 883 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 884 | * The :mod:`datetime` module has a new type :class:`~datetime.timezone` that |
| 885 | implements the :class:`~datetime.tzinfo` interface by returning a fixed UTC |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 886 | offset and timezone name. This makes it easier to create timezone-aware |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 887 | datetime objects: |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 888 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 889 | >>> datetime.now(timezone.utc) |
| 890 | 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] | 891 | |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 892 | >>> datetime.strptime("01/01/2000 12:00 +0000", "%m/%d/%Y %H:%M %z") |
| 893 | datetime.datetime(2000, 1, 1, 12, 0, tzinfo=datetime.timezone.utc) |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 894 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 895 | * Also, :class:`~datetime.timedelta` objects can now be multiplied by |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 896 | :class:`float` and divided by :class:`float` and :class:`int` objects. |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 897 | And :class:`~datetime.timedelta` objects can now divide one another. |
Raymond Hettinger | 792c076 | 2010-12-09 16:41:54 +0000 | [diff] [blame] | 898 | |
Raymond Hettinger | ca904be | 2011-01-18 00:02:40 +0000 | [diff] [blame] | 899 | * The :meth:`datetime.date.strftime` method is no longer restricted to years |
| 900 | after 1900. The new supported year range is from 1000 to 9999 inclusive. |
Alexander Belopolsky | 7257231 | 2010-12-08 21:21:56 +0000 | [diff] [blame] | 901 | |
Raymond Hettinger | 9767365 | 2011-01-11 21:13:26 +0000 | [diff] [blame] | 902 | * The rules for two-digit years in time tuples have changed. Now, the |
| 903 | :func:`time.asctime` and :func:`time.strftime` functions will format any year |
| 904 | when :attr:`time.accept2dyear` is false and will accept four-digit years |
| 905 | otherwise. The :func:`time.mktime` and :func:`time.strftime` functions now |
| 906 | accept full range supported by the operating system. Conversion of two-digit |
| 907 | years to four-digit is deprecated. |
Alexander Belopolsky | bd96b06 | 2011-01-10 21:55:34 +0000 | [diff] [blame] | 908 | |
Raymond Hettinger | 9767365 | 2011-01-11 21:13:26 +0000 | [diff] [blame] | 909 | (Contributed by Alexander Belopolsky and Victor Stinner.) |
Alexander Belopolsky | bd96b06 | 2011-01-10 21:55:34 +0000 | [diff] [blame] | 910 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 911 | abc |
| 912 | --- |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 913 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 914 | The :mod:`abc` module now supports :func:`~abc.abstractclassmethod` and |
| 915 | :func:`~abc.abstractstaticmethod`. |
Raymond Hettinger | a5a3554 | 2010-12-05 00:39:18 +0000 | [diff] [blame] | 916 | |
Raymond Hettinger | 7ec790d | 2011-01-18 00:19:30 +0000 | [diff] [blame^] | 917 | These tools make it possible to define an :term:`abstract base class` that |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 918 | requires a particular :func:`classmethod` or :func:`staticmethod` to be |
Raymond Hettinger | 7ec790d | 2011-01-18 00:19:30 +0000 | [diff] [blame^] | 919 | implemented:: |
| 920 | |
| 921 | class Temperature(metaclass=ABCMeta): |
| 922 | @abc.abstractclassmethod |
| 923 | def from_farenheit(self, t): |
| 924 | ... |
| 925 | @abc.abstractclassmethod |
| 926 | def from_celsium(self, t): |
| 927 | ... |
Antoine Pitrou | 7d49bc9 | 2010-09-15 15:13:17 +0000 | [diff] [blame] | 928 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 929 | (Patch submitted by Daniel Urban; :issue:`5867`.) |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 930 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 931 | contextlib |
| 932 | ---------- |
| 933 | |
| 934 | There is a new and slightly mind-blowing tool |
| 935 | :class:`~contextlib.ContextDecorator` that is helpful for creating a |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 936 | :term:`context manager` that does double duty as a function decorator. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 937 | |
| 938 | As a convenience, this new functionality is used by |
| 939 | :func:`~contextlib.contextmanager` so that no extra effort is needed to support |
| 940 | both roles. |
| 941 | |
| 942 | The basic idea is that both context managers and function decorators can be used |
| 943 | for pre-action and post-action wrappers. Context managers wrap a group of |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 944 | statements using the :keyword:`with` statement, and function decorators wrap a |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 945 | group of statements enclosed in a function. So, occasionally there is a need to |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 946 | write a pre-action or post-action wrapper that can be used in either role. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 947 | |
| 948 | For example, it is sometimes useful to wrap functions or groups of statements |
| 949 | with a logger that can track the time of entry and time of exit. Rather than |
| 950 | writing both a function decorator and a context manager for the task, the |
| 951 | :func:`~contextlib.contextmanager` provides both capabilities in a single |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 952 | definition:: |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 953 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 954 | import logging |
| 955 | logging.basicConfig(level=logging.INFO) |
| 956 | @contextmanager |
| 957 | def track_entry_and_exit(name): |
| 958 | logging.info('Entering: {}'.format(name)) |
| 959 | yield |
| 960 | logging.info('Exiting: {}'.format(name)) |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 961 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 962 | Formerly, this would have only been usable as a context manager:: |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 963 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 964 | with track_entry_and_exit('widget loader'): |
| 965 | print('Some time consuming activity goes here') |
| 966 | load_widget() |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 967 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 968 | Now, it can be used as a decorator as well:: |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 969 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 970 | @track_entry_and_exit('widget loader') |
| 971 | def activity(): |
| 972 | print('Some time consuming activity goes here') |
| 973 | load_widget() |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 974 | |
| 975 | Trying to fulfill two roles at once places some limitations on the technique. |
| 976 | Context managers normally have the flexibility to return an argument usable by |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 977 | the :keyword:`with` statement, but there is no parallel for function decorators. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 978 | |
Raymond Hettinger | 9743e4f | 2010-12-16 02:24:12 +0000 | [diff] [blame] | 979 | In the above example, there is not a clean way for the *track_entry_and_exit* |
Raymond Hettinger | 388af4b | 2011-01-06 20:55:29 +0000 | [diff] [blame] | 980 | context manager to return a logging instance for use in the body of enclosed |
| 981 | statements. |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 982 | |
| 983 | (Contributed by Michael Foord in :issue:`9110`.) |
| 984 | |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 985 | decimal and fractions |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 986 | --------------------- |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 987 | |
| 988 | Mark Dickinson crafted an elegant and efficient scheme for assuring that |
| 989 | different numeric datatypes will have the same hash value whenever their actual |
| 990 | values are equal (:issue:`8188`):: |
| 991 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 992 | assert hash(Fraction(3, 2)) == hash(1.5) == \ |
| 993 | hash(Decimal("1.5")) == hash(complex(1.5, 0)) |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 994 | |
| 995 | An early decision to limit the inter-operability of various numeric types has |
| 996 | been relaxed. It is still unsupported (and ill-advised) to to have implicit |
| 997 | mixing in arithmetic expressions such as ``Decimal('1.1') + float('1.1')`` |
| 998 | because the latter loses information in the process of constructing the binary |
| 999 | float. However, since existing floating point value can be converted losslessly |
| 1000 | to either a decimal or rational representation, it makes sense to add them to |
| 1001 | the constructor and to support mixed-type comparisons. |
| 1002 | |
Raymond Hettinger | bb9686f | 2010-12-16 00:53:05 +0000 | [diff] [blame] | 1003 | * The :class:`decimal.Decimal` constructor now accepts :class:`float` objects |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 1004 | 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] | 1005 | method (:issue:`8257`). |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 1006 | |
| 1007 | * Mixed type comparisons are now fully supported so that |
| 1008 | :class:`~decimal.Decimal` objects can be directly compared with :class:`float` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1009 | and :class:`fractions.Fraction` (:issue:`2531` and :issue:`8188`). |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 1010 | |
| 1011 | Similar changes were made to :class:`fractions.Fraction` so that the |
| 1012 | :meth:`~fractions.Fraction.from_float()` and :meth:`~fractions.Fraction.from_decimal` |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1013 | methods are no longer needed (:issue:`8294`): |
| 1014 | |
| 1015 | >>> Decimal(1.1) |
| 1016 | Decimal('1.100000000000000088817841970012523233890533447265625') |
| 1017 | >>> Fraction(1.1) |
| 1018 | Fraction(2476979795053773, 2251799813685248) |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 1019 | |
| 1020 | Another useful change for the :mod:`decimal` module is that the |
| 1021 | :attr:`Context.clamp` attribute is now public. This is useful in creating |
| 1022 | contexts that correspond to the decimal interchange formats specified in IEEE |
| 1023 | 754 (see :issue:`8540`). |
| 1024 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1025 | (Contributed by Mark Dickinson and Raymond Hettinger.) |
Raymond Hettinger | 07a605b | 2010-12-15 22:35:03 +0000 | [diff] [blame] | 1026 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1027 | ftp |
| 1028 | --- |
Raymond Hettinger | bcbd696 | 2010-09-05 08:46:36 +0000 | [diff] [blame] | 1029 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1030 | The :class:`ftplib.FTP` class now supports the context manager protocol to |
| 1031 | unconditionally consume :exc:`socket.error` exceptions and to close the FTP |
| 1032 | connection when done:: |
Giampaolo Rodolà | bd576b7 | 2010-05-10 14:53:29 +0000 | [diff] [blame] | 1033 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1034 | >>> from ftplib import FTP |
| 1035 | >>> with FTP("ftp1.at.proftpd.org") as ftp: |
| 1036 | ... ftp.login() |
| 1037 | ... ftp.dir() |
| 1038 | ... |
| 1039 | '230 Anonymous login ok, restrictions apply.' |
| 1040 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 . |
| 1041 | dr-xr-xr-x 9 ftp ftp 154 May 6 10:43 .. |
| 1042 | dr-xr-xr-x 5 ftp ftp 4096 May 6 10:43 CentOS |
| 1043 | dr-xr-xr-x 3 ftp ftp 18 Jul 10 2008 Fedora |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1044 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1045 | Other file-like objects such as :class:`mmap.mmap` and :func:`fileinput.input` |
| 1046 | also grew auto-closing context managers:: |
| 1047 | |
| 1048 | with fileinput.input(files=('log1.txt', 'log2.txt')) as f: |
| 1049 | for line in f: |
| 1050 | process(line) |
| 1051 | |
| 1052 | (Contributed by Tarek Ziadé and Giampaolo Rodolà in :issue:`4972`, and |
| 1053 | by Georg Brandl in :issue:`8046` and :issue:`1286`.) |
Antoine Pitrou | 696e035 | 2010-08-08 22:18:46 +0000 | [diff] [blame] | 1054 | |
Antoine Pitrou | bcba434 | 2011-01-16 18:29:34 +0000 | [diff] [blame] | 1055 | The :class:`~ftplib.FTP_TLS` class now accepts a *context* parameter, which is a |
| 1056 | :class:`ssl.SSLContext` object allowing bundling SSL configuration options, |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1057 | certificates and private keys into a single (potentially long-lived) structure. |
Antoine Pitrou | bcba434 | 2011-01-16 18:29:34 +0000 | [diff] [blame] | 1058 | |
| 1059 | (Contributed by Giampaolo Rodolà; :issue:`8806`.) |
| 1060 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1061 | popen |
| 1062 | ----- |
| 1063 | |
| 1064 | The :func:`os.popen` and :func:`subprocess.Popen` functions now support |
Georg Brandl | 23e924f | 2011-01-15 17:05:20 +0000 | [diff] [blame] | 1065 | the :keyword:`with` statement for auto-closing of the file descriptors. |
Georg Brandl | 3ad4675 | 2010-12-05 07:59:29 +0000 | [diff] [blame] | 1066 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1067 | gzip and zipfile |
| 1068 | ---------------- |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 1069 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1070 | :class:`gzip.GzipFile` now implements the :class:`io.BufferedIOBase` |
| 1071 | :term:`abstract base class` (except for ``truncate()``). It also has a |
| 1072 | :meth:`~gzip.GzipFile.peek` method and supports unseekable as well as |
| 1073 | zero-padded file objects. |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1074 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1075 | The :mod:`gzip` module also gains the :func:`~gzip.compress` and |
| 1076 | :func:`~gzip.decompress` functions for easier in-memory compression and |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 1077 | decompression. Keep in mind that text needs to be encoded as :class:`bytes` |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1078 | before compressing and decompressing: |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1079 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1080 | >>> s = 'Three shall be the number thou shalt count, ' |
| 1081 | >>> s += 'and the number of the counting shall be three' |
| 1082 | >>> b = s.encode() # convert to utf-8 |
| 1083 | >>> len(b) |
| 1084 | 89 |
| 1085 | >>> c = gzip.compress(b) |
| 1086 | >>> len(c) |
| 1087 | 77 |
| 1088 | >>> gzip.decompress(c).decode()[:42] # decompress and convert to text |
| 1089 | 'Three shall be the number thou shalt count,' |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 1090 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1091 | (Contributed by Anand B. Pillai in :issue:`3488`; and by Antoine Pitrou, Nir |
| 1092 | Aides and Brian Curtin in :issue:`9962`, :issue:`1675951`, :issue:`7471` and |
| 1093 | :issue:`2846`.) |
| 1094 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1095 | Also, the :class:`zipfile.ZipExtFile` class was reworked internally to represent |
| 1096 | files stored inside an archive. The new implementation is significantly faster |
| 1097 | and can be wrapped in a :class:`io.BufferedReader` object for more speedups. It |
| 1098 | also solves an issue where interleaved calls to *read* and *readline* gave the |
| 1099 | wrong results. |
| 1100 | |
| 1101 | (Patch submitted by by Nir Aides in :issue:`7610`.) |
| 1102 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1103 | shutil |
| 1104 | ------ |
| 1105 | |
| 1106 | The :func:`shutil.copytree` function has two new options: |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1107 | |
Antoine Pitrou | 121a055 | 2011-01-16 18:16:52 +0000 | [diff] [blame] | 1108 | * *ignore_dangling_symlinks*: when ``symlinks=False`` so that the function |
| 1109 | copies the file pointed to by the symlink, not the symlink itself. This |
| 1110 | option will silence the error raised if the file doesn't exist. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1111 | |
Antoine Pitrou | 121a055 | 2011-01-16 18:16:52 +0000 | [diff] [blame] | 1112 | * *copy_function*: is a callable that will be used to copy files. |
| 1113 | :func:`shutil.copy2` is used by default. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1114 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1115 | (Contributed by Tarek Ziadé.) |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1116 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1117 | sqlite3 |
| 1118 | ------- |
Antoine Pitrou | e43f9d0 | 2010-08-08 23:24:50 +0000 | [diff] [blame] | 1119 | |
Raymond Hettinger | 6046e22 | 2010-12-16 00:21:08 +0000 | [diff] [blame] | 1120 | 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] | 1121 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1122 | * The :attr:`sqlite3.Connection.in_transit` attribute is true if there is an |
| 1123 | active transaction for uncommitted changes. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1124 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1125 | * The :meth:`sqlite3.Connection.enable_load_extension` and |
| 1126 | :meth:`sqlite3.Connection.load_extension` methods allows you to load SQLite |
| 1127 | extensions from ".so" files. One well-known extension is the fulltext-search |
| 1128 | extension distributed with SQLite. |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1129 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1130 | (Contributed by R. David Murray and Shashwat Anand; :issue:`8845`.) |
| 1131 | |
| 1132 | socket |
| 1133 | ------ |
| 1134 | |
| 1135 | The :mod:`socket` module has two new improvements. |
| 1136 | |
| 1137 | * Socket objects now have a :meth:`~socket.socket.detach()` method which puts |
| 1138 | the socket into closed state without actually closing the underlying file |
| 1139 | descriptor. The latter can then be reused for other purposes. |
| 1140 | (Added by Antoine Pitrou; :issue:`8524`.) |
| 1141 | |
| 1142 | * :func:`socket.create_connection` now supports the context manager protocol |
| 1143 | to unconditionally consume :exc:`socket.error` exceptions and to close the |
| 1144 | socket when done. |
| 1145 | (Contributed by Giampaolo Rodolà; :issue:`9794`.) |
| 1146 | |
| 1147 | ssl |
| 1148 | --- |
Antoine Pitrou | d67075e | 2010-07-31 22:48:02 +0000 | [diff] [blame] | 1149 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1150 | The :mod:`ssl` module added a number of features to satisfy common requirements |
| 1151 | for secure (encrypted, authenticated) internet connections: |
Antoine Pitrou | 33da1d6 | 2011-01-16 18:16:09 +0000 | [diff] [blame] | 1152 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1153 | * A new class, :class:`~ssl.SSLContext`, serves as a container for persistent |
| 1154 | SSL data, such as protocol settings, certificates, private keys, and various |
| 1155 | other options. It includes a :meth:`~ssl.SSLContext.wrap_socket` for creating |
| 1156 | an SSL socket from an SSL context. |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1157 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1158 | * A new function, :func:`ssl.match_hostname`, supports server identity |
| 1159 | verification for higher-level protocols by implementing the rules of HTTPS |
| 1160 | (from :rfc:`2818`) which are also suitable for other protocols. |
Antoine Pitrou | 0ee4c9f | 2010-10-08 16:46:17 +0000 | [diff] [blame] | 1161 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1162 | * The :func:`ssl.wrap_socket` constructor function now takes a *ciphers* |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1163 | argument. The *ciphers* string lists the allowed encryption algorithms using |
| 1164 | the format described in the `OpenSSL documentation |
| 1165 | <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`__. |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1166 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1167 | * When linked against recent versions of OpenSSL, the :mod:`ssl` module now |
| 1168 | supports the Server Name Indication extension to the TLS protocol, allowing |
| 1169 | multiple "virtual hosts" using different certificates on a single IP port. |
| 1170 | This extension is only supported in client mode, and is activated by passing |
| 1171 | the *server_hostname* argument to :meth:`ssl.SSLContext.wrap_socket`. |
Antoine Pitrou | 7d15a72 | 2010-11-05 22:13:55 +0000 | [diff] [blame] | 1172 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1173 | * Various options have been added to the :mod:`ssl` module, such as |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1174 | :data:`~ssl.OP_NO_SSLv2` which disables the insecure and obsolete SSLv2 |
| 1175 | protocol. |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1176 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1177 | * The extension now loads all the OpenSSL ciphers and digest algorithms. If |
| 1178 | some SSL certificates cannot be verified, they are reported as an "unknown |
| 1179 | algorithm" error. |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1180 | |
Raymond Hettinger | 4854d14 | 2011-01-17 21:29:58 +0000 | [diff] [blame] | 1181 | * The version of OpenSSL being used is now accessible using the module |
| 1182 | attributes :data:`ssl.OPENSSL_VERSION` (a string), |
| 1183 | :data:`ssl.OPENSSL_VERSION_INFO` (a 5-tuple), and |
| 1184 | :data:`ssl.OPENSSL_VERSION_NUMBER` (an integer). |
| 1185 | |
| 1186 | (Contributed by Antoine Pitrou in :issue:`8850`, :issue:`1589`, :issue:`8322`, |
| 1187 | :issue:`5639`, :issue:`4870`, :issue:`8484`, and :issue:`8321`.) |
Antoine Pitrou | 4f2a0a8 | 2010-07-31 18:08:33 +0000 | [diff] [blame] | 1188 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1189 | nntp |
| 1190 | ---- |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 1191 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1192 | The :mod:`nntplib` module has a revamped implementation with better bytes and |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1193 | text semantics as well as more practical APIs. These improvements break |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1194 | compatibility with the nntplib version in Python 3.1, which was partly |
| 1195 | dysfunctional in itself. |
Raymond Hettinger | 070ec70 | 2010-12-10 17:45:13 +0000 | [diff] [blame] | 1196 | |
Antoine Pitrou | 33da1d6 | 2011-01-16 18:16:09 +0000 | [diff] [blame] | 1197 | Support for secure connections through both implicit (using |
| 1198 | :class:`nntplib.NNTP_SSL`) and explicit (using :meth:`nntplib.NNTP.starttls`) |
| 1199 | TLS has also been added. |
| 1200 | |
| 1201 | (Contributed by Antoine Pitrou in :issue:`9360` and Andrew Vant in :issue:`1926`.) |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1202 | |
| 1203 | certificates |
| 1204 | ------------ |
| 1205 | |
| 1206 | :class:`http.client.HTTPSConnection`, :class:`urllib.request.HTTPSHandler` |
| 1207 | and :func:`urllib.request.urlopen` now take optional arguments to allow for |
| 1208 | server certificate checking against a set of Certificate Authorities, |
| 1209 | as recommended in public uses of HTTPS. |
| 1210 | |
| 1211 | (Added by Antoine Pitrou, :issue:`9003`.) |
| 1212 | |
Antoine Pitrou | 2e8ec22 | 2011-01-16 18:41:36 +0000 | [diff] [blame] | 1213 | imaplib |
| 1214 | ------- |
| 1215 | |
| 1216 | Support for explicit TLS on standard IMAP4 connections has been added through |
| 1217 | the new :mod:`imaplib.IMAP4.starttls` method. |
| 1218 | |
| 1219 | (Contributed by Lorenzo M. Catucci and Antoine Pitrou, :issue:`4471`.) |
| 1220 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1221 | unittest |
| 1222 | -------- |
Antoine Pitrou | afb078d | 2010-11-05 22:18:28 +0000 | [diff] [blame] | 1223 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1224 | The unittest module has a number of improvements supporting test discovery for |
| 1225 | packages, easier experimentation at the interactive prompt, new testcase |
| 1226 | methods, improved diagnostic messages for test failures, and better method |
| 1227 | names. |
| 1228 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1229 | * The command-line call ``python -m unittest`` can now accept file paths |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1230 | instead of module names for running specific tests (:issue:`10620`). The new |
| 1231 | test discovery can find tests within packages, locating any test importable |
| 1232 | from the top level directory. The top level directory can be specified with |
| 1233 | the `-t` option, a pattern for matching files with ``-p``, and a directory to |
| 1234 | start discovery with ``-s``:: |
| 1235 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1236 | $ python -m unittest discover -s my_proj_dir -p _test.py |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1237 | |
| 1238 | (Contributed by Michael Foord.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1239 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1240 | * Experimentation at the interactive prompt is now easier because the |
| 1241 | :class:`unittest.case.TestCase` class can now be instantiated without |
| 1242 | arguments: |
| 1243 | |
| 1244 | >>> TestCase().assertEqual(pow(2, 3), 8) |
| 1245 | |
| 1246 | (Contributed by Michael Foord.) |
| 1247 | |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1248 | * The :mod:`unittest` module has two new methods, |
| 1249 | :meth:`~unittest.TestCase.assertWarns` and |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1250 | :meth:`~unittest.TestCase.assertWarnsRegex` to verify that a given warning type |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1251 | is triggered by the code under test:: |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1252 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1253 | with self.assertWarns(DeprecationWarning): |
| 1254 | legacy_function('XYZ') |
Ezio Melotti | 2baf1a6 | 2010-11-22 12:56:58 +0000 | [diff] [blame] | 1255 | |
Antoine Pitrou | eec6dbf | 2011-01-16 18:21:12 +0000 | [diff] [blame] | 1256 | (Contributed by Antoine Pitrou, :issue:`9754`.) |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1257 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1258 | Another new method, :meth:`~unittest.TestCase.assertCountEqual` is used to |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 1259 | compare two iterables to determine if their element counts are equal (whether |
| 1260 | the same elements are present with the same number of occurrences regardless |
| 1261 | of order):: |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1262 | |
| 1263 | def test_anagram(self): |
| 1264 | self.assertCountEqual('algorithm', 'logarithm') |
| 1265 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1266 | (Contributed by Raymond Hettinger.) |
| 1267 | |
| 1268 | * A principal feature of the unittest module is an effort to produce meaningful |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1269 | diagnostics when a test fails. When possible, the failure is recorded along |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1270 | with a diff of the output. This is especially helpful for analyzing log files |
| 1271 | of failed test runs. However, since diffs can sometime be voluminous, there is |
| 1272 | a new :attr:`~unittest.TestCase.maxDiff` attribute which sets maximum length of |
| 1273 | diffs. |
| 1274 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1275 | * In addition, the method names in the module have undergone a number of clean-ups. |
| 1276 | |
| 1277 | For example, :meth:`~unittest.TestCase.assertRegex` is the new name for |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1278 | :meth:`~unittest.TestCase.assertRegexpMatches` which was misnamed because the |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1279 | test uses :func:`re.search`, not :func:`re.match`. Other methods using |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1280 | regular expressions are now named using short form "Regex" in preference to |
| 1281 | "Regexp" -- this matches the names used in other unittest implementations, |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1282 | matches Python's old name for the :mod:`re` module, and it has unambiguous |
| 1283 | camel-casing. |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1284 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1285 | (Contributed by Raymond Hettinger and implemented by Ezio Melotti.) |
| 1286 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1287 | * To improve consistency, some long-standing method aliases are being |
Raymond Hettinger | dc2f9b5 | 2010-12-05 07:02:45 +0000 | [diff] [blame] | 1288 | deprecated in favor of the preferred names: |
| 1289 | |
| 1290 | - replace :meth:`assert_` with :meth:`.assertTrue` |
| 1291 | - replace :meth:`assertEquals` with :meth:`.assertEqual` |
| 1292 | - replace :meth:`assertNotEquals` with :meth:`.assertNotEqual` |
| 1293 | - replace :meth:`assertAlmostEquals` with :meth:`.assertAlmostEqual` |
| 1294 | - replace :meth:`assertNotAlmostEquals` with :meth:`.assertNotAlmostEqual` |
| 1295 | |
| 1296 | Likewise, the ``TestCase.fail*`` methods deprecated in Python 3.1 are expected |
| 1297 | to be removed in Python 3.3. See also the :ref:`deprecated-aliases` section in |
| 1298 | the :mod:`unittest` documentation. |
Ezio Melotti | 2baf1a6 | 2010-11-22 12:56:58 +0000 | [diff] [blame] | 1299 | |
| 1300 | (Contributed by Ezio Melotti; :issue:`9424`.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1301 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1302 | * The :meth:`~unittest.TestCase.assertDictContainsSubset` method was deprecated |
| 1303 | because it was mis-implemented with the arguments in the wrong order. This |
| 1304 | created hard-to-debug optical illusions where tests like |
| 1305 | ``TestCase().assertDictContainsSubset({'a':1, 'b':2}, {'a':1})`` would fail. |
| 1306 | |
| 1307 | (Contributed by Raymond Hettinger.) |
| 1308 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1309 | random |
| 1310 | ------ |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1311 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1312 | 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] | 1313 | uniform distributions. Previously, they computed selections with |
| 1314 | ``int(n*random())`` which had a slight bias whenever *n* was not a power of two. |
| 1315 | Now, multiple selections are made from a range upto the next power of two and a |
| 1316 | selection is kept only when it falls within the range ``0 <= x < n``. The |
| 1317 | functions and methods affected are :func:`~random.randrange`, |
| 1318 | :func:`~random.randint`, :func:`~random.choice`, :func:`~random.shuffle` and |
| 1319 | :func:`~random.sample`. |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1320 | |
| 1321 | (Contributed by Raymond Hettinger; :issue:`9025`.) |
| 1322 | |
| 1323 | poplib |
| 1324 | ------ |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1325 | |
Giampaolo Rodolà | 42382fe | 2010-08-17 16:09:53 +0000 | [diff] [blame] | 1326 | * :class:`~poplib.POP3_SSL` class now accepts a *context* parameter, which is a |
| 1327 | :class:`ssl.SSLContext` object allowing bundling SSL configuration options, |
| 1328 | certificates and private keys into a single (potentially long-lived) |
| 1329 | structure. |
| 1330 | |
| 1331 | (Contributed by Giampaolo Rodolà; :issue:`8807`.) |
| 1332 | |
Giampaolo Rodolà | 977c707 | 2010-10-04 21:08:36 +0000 | [diff] [blame] | 1333 | * :class:`asyncore.dispatcher` now provides a |
| 1334 | :meth:`~asyncore.dispatcher.handle_accepted()` method |
| 1335 | returning a `(sock, addr)` pair which is called when a connection has actually |
| 1336 | been established with a new remote endpoint. This is supposed to be used as a |
| 1337 | replacement for old :meth:`~asyncore.dispatcher.handle_accept()` and avoids |
| 1338 | the user to call :meth:`~asyncore.dispatcher.accept()` directly. |
| 1339 | |
| 1340 | (Contributed by Giampaolo Rodolà; :issue:`6706`.) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1341 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1342 | tempfile |
| 1343 | -------- |
Raymond Hettinger | a026633 | 2010-12-07 08:52:41 +0000 | [diff] [blame] | 1344 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1345 | The :mod:`tempfile` module has a new context manager, |
| 1346 | :class:`~tempfile.TemporaryDirectory` which provides easy deterministic |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1347 | cleanup of temporary directories:: |
Nick Coghlan | 543af75 | 2010-10-24 11:23:25 +0000 | [diff] [blame] | 1348 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1349 | with tempfile.TemporaryDirectory() as tmpdirname: |
| 1350 | print('created temporary dir:', tmpdirname) |
Nick Coghlan | 543af75 | 2010-10-24 11:23:25 +0000 | [diff] [blame] | 1351 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1352 | (Contributed by Neil Schemenauer and Nick Coghlan; :issue:`5178`.) |
Nick Coghlan | e0f0465 | 2010-11-21 03:44:04 +0000 | [diff] [blame] | 1353 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1354 | inspect |
| 1355 | ------- |
| 1356 | |
Raymond Hettinger | 0358a17 | 2010-12-15 19:00:38 +0000 | [diff] [blame] | 1357 | * The :mod:`inspect` module has a new function |
| 1358 | :func:`~inspect.getgeneratorstate` to easily identify the current state of a |
| 1359 | generator as one of ``GEN_CREATED``, ``GEN_RUNNING``, ``GEN_SUSPENDED`` or |
| 1360 | ``GEN_CLOSED``. (Contributed by Rodolpho Eckhardt and Nick Coghlan, |
| 1361 | :issue:`10220`.) |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1362 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1363 | * To support lookups without the possibility of activating a dynamic attribute, |
| 1364 | the :mod:`inspect` module has a new function, :func:`~inspect.getattr_static`. |
| 1365 | Unlike, :func:`hasattr`, this is a true read-only search, guaranteed not to |
| 1366 | change state while it is searching. (Contributed by Michael Foord.) |
Nick Coghlan | e0f0465 | 2010-11-21 03:44:04 +0000 | [diff] [blame] | 1367 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1368 | pydoc |
| 1369 | ----- |
Nick Coghlan | 7bb30b7 | 2010-12-03 09:29:11 +0000 | [diff] [blame] | 1370 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1371 | The :mod:`pydoc` module now provides a much improved Web server interface, |
| 1372 | as well as a new command-line option to automatically open a browser |
| 1373 | window to display that server. |
Nick Coghlan | 7bb30b7 | 2010-12-03 09:29:11 +0000 | [diff] [blame] | 1374 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1375 | (Contributed by Ron Adam; :issue:`2001`.) |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1376 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1377 | sysconfig |
| 1378 | --------- |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1379 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1380 | The new :mod:`sysconfig` module makes it straightforward to discover |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1381 | installation paths and configuration variables which vary across platforms and |
| 1382 | installations. |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1383 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1384 | The module offers access simple access functions for platform and version |
| 1385 | information: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1386 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1387 | * :func:`~sysconfig.get_platform` returning values like *linux-i586* or |
| 1388 | *macosx-10.6-ppc*. |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1389 | * :func:`~sysconfig.get_python_version` returns a Python version string |
| 1390 | such as "3.2". |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1391 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1392 | It also provides access to the paths and variables corresponding to one of |
| 1393 | seven named schemes used by :mod:`distutils`. Those include *posix_prefix*, |
| 1394 | *posix_home*, *posix_user*, *nt*, *nt_user*, *os2*, *os2_home*: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1395 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1396 | * :func:`~sysconfig.get_paths` makes a dictionary containing installation paths |
| 1397 | for the current installation scheme. |
| 1398 | * :func:`~sysconfig.get_config_vars` returns a dictionary of platform specific |
| 1399 | variables. |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1400 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1401 | There is also a convenient command-line interface:: |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1402 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1403 | C:\Python32>python -m sysconfig |
| 1404 | Platform: "win32" |
| 1405 | Python version: "3.2" |
| 1406 | Current installation scheme: "nt" |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1407 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1408 | Paths: |
| 1409 | data = "C:\Python32" |
Łukasz Langa | 79a06ed | 2010-12-17 22:05:46 +0000 | [diff] [blame] | 1410 | include = "C:\Python32\Include" |
| 1411 | platinclude = "C:\Python32\Include" |
| 1412 | platlib = "C:\Python32\Lib\site-packages" |
| 1413 | platstdlib = "C:\Python32\Lib" |
| 1414 | purelib = "C:\Python32\Lib\site-packages" |
| 1415 | scripts = "C:\Python32\Scripts" |
| 1416 | stdlib = "C:\Python32\Lib" |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1417 | |
| 1418 | Variables: |
| 1419 | BINDIR = "C:\Python32" |
Łukasz Langa | 79a06ed | 2010-12-17 22:05:46 +0000 | [diff] [blame] | 1420 | BINLIBDEST = "C:\Python32\Lib" |
| 1421 | EXE = ".exe" |
| 1422 | INCLUDEPY = "C:\Python32\Include" |
| 1423 | LIBDEST = "C:\Python32\Lib" |
| 1424 | SO = ".pyd" |
| 1425 | VERSION = "32" |
| 1426 | abiflags = "" |
| 1427 | base = "C:\Python32" |
| 1428 | exec_prefix = "C:\Python32" |
| 1429 | platbase = "C:\Python32" |
| 1430 | prefix = "C:\Python32" |
| 1431 | projectbase = "C:\Python32" |
| 1432 | py_version = "3.2" |
| 1433 | py_version_nodot = "32" |
| 1434 | py_version_short = "3.2" |
| 1435 | srcdir = "C:\Python32" |
| 1436 | userbase = "C:\Documents and Settings\Raymond\Application Data\Python" |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1437 | |
| 1438 | pdb |
| 1439 | --- |
| 1440 | |
| 1441 | The :mod:`pdb` debugger module gained a number of usability improvements: |
Raymond Hettinger | b5d7933 | 2010-12-07 02:04:56 +0000 | [diff] [blame] | 1442 | |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1443 | * :file:`pdb.py` now has a ``-c`` option that executes commands as given in a |
| 1444 | :file:`.pdbrc` script file. |
| 1445 | * A :file:`.pdbrc` script file can contain ``continue`` and ``next`` commands |
| 1446 | that continue debugging. |
| 1447 | * The :class:`Pdb` class constructor now accepts a *nosigint* argument. |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 1448 | * New commands: ``l(list)``, ``ll(long list)`` and ``source`` for |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1449 | listing source code. |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1450 | * New commands: ``display`` and ``undisplay`` for showing or hiding |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1451 | the value of an expression if it has changed. |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1452 | * New command: ``interact`` for starting an interactive interpreter containing |
Raymond Hettinger | 99db3fd | 2010-12-15 19:33:49 +0000 | [diff] [blame] | 1453 | the global and local names found in the current scope. |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1454 | * Breakpoints can be cleared by breakpoint number. |
Raymond Hettinger | b5d7933 | 2010-12-07 02:04:56 +0000 | [diff] [blame] | 1455 | |
Georg Brandl | 101234b | 2010-12-18 11:53:25 +0000 | [diff] [blame] | 1456 | (Contributed by Georg Brandl, Antonio Cuni and Ilya Sandler.) |
| 1457 | |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1458 | configparser |
| 1459 | ------------ |
Raymond Hettinger | 3f9734c | 2010-12-07 01:47:52 +0000 | [diff] [blame] | 1460 | |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1461 | The :mod:`configparser` module was modified to improve usability and |
| 1462 | predictability of the default parser and its supported INI syntax. The old |
| 1463 | :class:`ConfigParser` class was removed in favor of :class:`SafeConfigParser` |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1464 | which has in turn been renamed to :class:`~configparser.ConfigParser`. Support |
| 1465 | for inline comments is now turned off by default and section or option |
| 1466 | duplicates are not allowed in a single configuration source. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1467 | |
| 1468 | Config parsers gained a new API based on the mapping protocol:: |
| 1469 | |
Raymond Hettinger | 02dd70b | 2011-01-17 23:39:39 +0000 | [diff] [blame] | 1470 | >>> parser = ConfigParser() |
| 1471 | >>> parser.read_string(""" |
| 1472 | [DEFAULT] |
| 1473 | location = upper left |
| 1474 | visible = yes |
| 1475 | editable = no |
| 1476 | color = blue |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1477 | |
Raymond Hettinger | 02dd70b | 2011-01-17 23:39:39 +0000 | [diff] [blame] | 1478 | [main] |
| 1479 | title = Main Menu |
| 1480 | color = green |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1481 | |
Raymond Hettinger | 02dd70b | 2011-01-17 23:39:39 +0000 | [diff] [blame] | 1482 | [options] |
| 1483 | title = Options |
| 1484 | """) |
| 1485 | >>> parser['main']['color'] |
| 1486 | 'green' |
| 1487 | >>> parser['main']['editable'] |
| 1488 | 'no' |
| 1489 | >>> section = parser['options'] |
| 1490 | >>> section['title'] |
| 1491 | 'Options' |
| 1492 | >>> section['title'] = 'Options (editable: %(editable)s)' |
| 1493 | >>> section['title'] |
| 1494 | 'Options (editable: no)' |
| 1495 | |
| 1496 | 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] | 1497 | subclasses should be able to use it without modifications. |
| 1498 | |
| 1499 | 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] | 1500 | can specify alternative option/value delimiters and comment prefixes, change the |
Raymond Hettinger | 02dd70b | 2011-01-17 23:39:39 +0000 | [diff] [blame] | 1501 | name of the *DEFAULT* section or switch the interpolation syntax. |
| 1502 | |
| 1503 | The is support for pluggable interpolation including an additional interpolation |
| 1504 | handler :class:`~configparser.ExtendedInterpolation`:: |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1505 | |
| 1506 | >>> parser = ConfigParser(interpolation=ExtendedInterpolation()) |
| 1507 | >>> parser.read_dict({'buildout': {'directory': '/home/ambv/zope9'}, |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1508 | 'custom': {'prefix': '/usr/local'}}) |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1509 | >>> parser.read_string(""" |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1510 | [buildout] |
| 1511 | parts = |
| 1512 | zope9 |
| 1513 | instance |
| 1514 | find-links = |
| 1515 | ${buildout:directory}/downloads/dist |
| 1516 | |
| 1517 | [zope9] |
| 1518 | recipe = plone.recipe.zope9install |
| 1519 | location = /opt/zope |
| 1520 | |
| 1521 | [instance] |
| 1522 | recipe = plone.recipe.zope9instance |
| 1523 | zope9-location = ${zope9:location} |
| 1524 | zope-conf = ${custom:prefix}/etc/zope.conf |
| 1525 | """) |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1526 | >>> parser['buildout']['find-links'] |
| 1527 | '\n/home/ambv/zope9/downloads/dist' |
| 1528 | >>> parser['instance']['zope-conf'] |
| 1529 | '/usr/local/etc/zope.conf' |
| 1530 | >>> instance = parser['instance'] |
| 1531 | >>> instance['zope-conf'] |
| 1532 | '/usr/local/etc/zope.conf' |
| 1533 | >>> instance['zope9-location'] |
| 1534 | '/opt/zope' |
| 1535 | |
| 1536 | A number of smaller features were also introduced, like support for specifying |
Raymond Hettinger | 0412974 | 2010-12-18 10:57:50 +0000 | [diff] [blame] | 1537 | encoding in read operations, specifying fallback values for get-functions, or |
| 1538 | reading directly from dictionaries and strings. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1539 | |
| 1540 | (All changes contributed by Łukasz Langa.) |
| 1541 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1542 | .. XXX: Mention urllib.parse changes |
| 1543 | Issue 9873 (Nick Coghlan): |
| 1544 | - ASCII byte sequence support in URL parsing |
| 1545 | - named tuple for urldefrag return value |
| 1546 | Issue 5468 (Dan Mahn) for urlencode: |
| 1547 | - bytes input support |
| 1548 | - non-UTF8 percent encoding of non-ASCII characters |
| 1549 | Issue 2987 for IPv6 (RFC2732) support in urlparse |
Raymond Hettinger | 3df4621 | 2011-01-06 02:01:26 +0000 | [diff] [blame] | 1550 | |
Raymond Hettinger | a55ffbc | 2010-12-15 18:31:57 +0000 | [diff] [blame] | 1551 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1552 | Multi-threading |
| 1553 | =============== |
| 1554 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1555 | * The mechanism for serializing execution of concurrently running Python threads |
| 1556 | (generally known as the GIL or Global Interpreter Lock) has been rewritten. |
| 1557 | Among the objectives were more predictable switching intervals and reduced |
| 1558 | overhead due to lock contention and the number of ensuing system calls. The |
| 1559 | notion of a "check interval" to allow thread switches has been abandoned and |
| 1560 | replaced by an absolute duration expressed in seconds. This parameter is |
| 1561 | tunable through :func:`sys.setswitchinterval()`. It currently defaults to 5 |
| 1562 | milliseconds. |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1563 | |
| 1564 | Additional details about the implementation can be read from a `python-dev |
| 1565 | mailing-list message |
| 1566 | <http://mail.python.org/pipermail/python-dev/2009-October/093321.html>`_ |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1567 | (however, "priority requests" as exposed in this message have not been kept |
| 1568 | for inclusion). |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1569 | |
Georg Brandl | 5e73a81 | 2010-04-22 07:02:51 +0000 | [diff] [blame] | 1570 | (Contributed by Antoine Pitrou.) |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1571 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1572 | * Regular and recursive locks now accept an optional *timeout* argument to their |
Raymond Hettinger | 09e4ebb | 2010-09-06 19:55:51 +0000 | [diff] [blame] | 1573 | :meth:`acquire` method. (Contributed by Antoine Pitrou; :issue:`7316`.) |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1574 | |
Raymond Hettinger | bba537b | 2010-12-15 18:20:19 +0000 | [diff] [blame] | 1575 | * Similarly, :meth:`threading.Semaphore.acquire` also gained a *timeout* |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1576 | argument. (Contributed by Torsten Landschoff; :issue:`850728`.) |
Antoine Pitrou | e95a9ff | 2010-05-04 23:31:41 +0000 | [diff] [blame] | 1577 | |
Antoine Pitrou | 810023d | 2010-12-15 22:59:16 +0000 | [diff] [blame] | 1578 | * Regular and recursive lock acquisitions can now be interrupted by signals on |
| 1579 | platforms using pthreads. This means that Python programs that deadlock while |
| 1580 | acquiring locks can be successfully killed by repeatedly sending SIGINT to the |
Georg Brandl | eebb252 | 2010-12-18 12:01:15 +0000 | [diff] [blame] | 1581 | process (by pressing :kbd:`Ctrl+C` in most shells). |
Antoine Pitrou | 810023d | 2010-12-15 22:59:16 +0000 | [diff] [blame] | 1582 | (Contributed by Reid Kleckner; :issue:`8844`.) |
| 1583 | |
Antoine Pitrou | d42bc51 | 2009-11-10 23:18:31 +0000 | [diff] [blame] | 1584 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 1585 | Optimizations |
| 1586 | ============= |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1587 | |
Raymond Hettinger | 92ba286 | 2010-09-06 01:16:46 +0000 | [diff] [blame] | 1588 | A number of small performance enhancements have been added: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1589 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1590 | * 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] | 1591 | being a test for membership in a set of constants. The optimizer recasts the |
| 1592 | :class:`set` as a :class:`frozenset` and stores the pre-built constant. |
| 1593 | |
| 1594 | Now that the speed penalty is gone, it is practical to start writing |
| 1595 | membership tests using set-notation. This style is both semantically clear |
| 1596 | and operationally fast:: |
| 1597 | |
| 1598 | extension = name.rpartition('.')[2] |
| 1599 | if extension in {'xml', 'html', 'xhtml', 'css'}: |
| 1600 | handle(name) |
| 1601 | |
| 1602 | (Patch and additional tests by Dave Malcolm; :issue:`6690`). |
| 1603 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1604 | * Serializing and unserializing data using the :mod:`pickle` module is now |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1605 | several times faster. |
| 1606 | |
| 1607 | (Contributed by Alexandre Vassalotti, Antoine Pitrou |
Antoine Pitrou | ff150f2 | 2010-10-22 21:41:05 +0000 | [diff] [blame] | 1608 | and the Unladen Swallow team in :issue:`9410` and :issue:`3873`.) |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1609 | |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1610 | * The `Timsort algorithm <http://en.wikipedia.org/wiki/Timsort>`_ used in |
Raymond Hettinger | ffad35e | 2010-12-14 21:12:03 +0000 | [diff] [blame] | 1611 | :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] | 1612 | when called with a :term:`key function`. Previously, every element of |
| 1613 | a list was wrapped with a temporary object that remembered the key value |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1614 | associated with each element. Now, two arrays of keys and values are |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1615 | sorted in parallel. This save the memory consumed by the sort wrappers, |
Michael Foord | eaedfcb | 2010-12-22 18:28:51 +0000 | [diff] [blame] | 1616 | and it saves time lost during comparisons which were delegated by the |
Michael Foord | 5e9b14c | 2010-12-22 10:39:04 +0000 | [diff] [blame] | 1617 | sort wrappers. |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1618 | |
Raymond Hettinger | eb70b90 | 2011-01-10 21:26:49 +0000 | [diff] [blame] | 1619 | (Patch by Daniel Stutzbach in :issue:`9915`.) |
Raymond Hettinger | c269ae8 | 2010-12-05 01:01:52 +0000 | [diff] [blame] | 1620 | |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1621 | * JSON decoding performance is improved and memory consumption is reduced |
Raymond Hettinger | 413abbc | 2010-12-05 07:06:47 +0000 | [diff] [blame] | 1622 | whenever the same string is repeated for multiple keys. Also, JSON encoding |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1623 | now uses the C speedups when the ``sort_keys`` argument is true. |
| 1624 | |
| 1625 | (Contributed by Antoine Pitrou in :issue:`7451` and by Raymond Hettinger and |
| 1626 | Antoine Pitrou in :issue:`10314`.) |
| 1627 | |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1628 | * Recursive locks (created with the :func:`threading.RLock` API) now benefit |
| 1629 | from a C implementation which makes them as fast as regular locks, and between |
| 1630 | 10x and 15x faster than their previous pure Python implementation. |
| 1631 | |
| 1632 | (Contributed by Antoine Pitrou; :issue:`3001`.) |
| 1633 | |
Raymond Hettinger | dadf93c | 2010-12-05 02:56:21 +0000 | [diff] [blame] | 1634 | * The fast-search algorithm in stringlib is now used by the :meth:`split`, |
| 1635 | :meth:`rsplit`, :meth:`splitlines` and :meth:`replace` methods on |
| 1636 | :class:`bytes`, :class:`bytearray` and :class:`str` objects. Likewise, the |
| 1637 | algorithm is also used by :meth:`rfind`, :meth:`rindex`, :meth:`rsplit` and |
| 1638 | :meth:`rpartition`. |
| 1639 | |
| 1640 | (Patch by Florent Xicluna in :issue:`7622` and :issue:`7462`.) |
| 1641 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1642 | |
| 1643 | * String to integer conversions now work two "digits" at a time, reducing the |
| 1644 | number of division and modulo operations. |
| 1645 | |
| 1646 | (:issue:`6713` by Gawain Bolton, Mark Dickinson, and Victor Stinner.) |
| 1647 | |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 1648 | There were several other minor optimizations. Set differencing now runs faster |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1649 | when one operand is much larger than the other (patch by Andress Bennetts in |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 1650 | :issue:`8685`). The :meth:`array.repeat` method has a faster implementation |
| 1651 | (:issue:`1569291` by Alexander Belopolsky). The :class:`BaseHTTPRequestHandler` |
| 1652 | has more efficient buffering (:issue:`3709` by Andrew Schaaf). The |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1653 | multi-argument form of :func:`operator.attrgetter` function now runs slightly |
Raymond Hettinger | d8fae4e | 2010-12-05 05:39:54 +0000 | [diff] [blame] | 1654 | faster (:issue:`10160` by Christos Georgiou). And :class:`ConfigParser` loads |
| 1655 | multi-line arguments a bit faster (:issue:`7113` by Łukasz Langa). |
| 1656 | |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1657 | |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1658 | Unicode |
| 1659 | ======= |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 1660 | |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1661 | Python has been updated to Unicode 6.0.0. The new features of the |
| 1662 | Unicode Standard that will affect Python users include: |
| 1663 | |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1664 | * addition of 2,088 characters, including over 1,000 additional |
| 1665 | symbols—chief among them the additional emoji symbols, which are |
| 1666 | especially important for mobile phones; |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1667 | |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1668 | * changes to character properties for existing characters including |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1669 | |
Raymond Hettinger | c74d518 | 2010-12-02 01:38:25 +0000 | [diff] [blame] | 1670 | - a general category change to two Kannada characters (U+0CF1, |
| 1671 | U+0CF2), which has the effect of making them newly eligible for |
| 1672 | inclusion in identifiers; |
| 1673 | |
| 1674 | - a general category change to one New Tai Lue numeric character |
Alexander Belopolsky | 84cc062 | 2010-12-08 21:38:46 +0000 | [diff] [blame] | 1675 | (U+19DA), which has the effect of disqualifying it from |
| 1676 | inclusion in identifiers. |
| 1677 | |
| 1678 | For more information, see `Unicode Character Database Changes |
| 1679 | <http://www.unicode.org/versions/Unicode6.0.0/#Database_Changes>`_ |
| 1680 | at the `Unicode Consortium <http://www.unicode.org/>`_ web site. |
Alexander Belopolsky | 507e3f8 | 2010-12-02 00:05:57 +0000 | [diff] [blame] | 1681 | |
Éric Araujo | 4234ad4 | 2010-09-05 17:32:25 +0000 | [diff] [blame] | 1682 | The :mod:`os` module has two new functions: :func:`~os.fsencode` and |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1683 | :func:`~os.fsdecode`. Add :data:`os.environb`: bytes version of |
| 1684 | :data:`os.environ`, :func:`os.getenvb` function and |
| 1685 | :data:`os.supports_bytes_environ` constant. |
Victor Stinner | e8d5145 | 2010-08-19 01:05:19 +0000 | [diff] [blame] | 1686 | |
Georg Brandl | 326c57d | 2010-11-26 12:10:06 +0000 | [diff] [blame] | 1687 | ``'mbcs'`` encoding doesn't ignore the error handler argument any more. By |
Victor Stinner | 47ce965 | 2010-10-29 00:57:35 +0000 | [diff] [blame] | 1688 | default (strict mode), it raises an UnicodeDecodeError on undecodable byte |
| 1689 | sequence and UnicodeEncodeError on unencodable character. To get the ``'mbcs'`` |
| 1690 | encoding of Python 3.1, use ``'ignore'`` error handler to decode and |
| 1691 | ``'replace'`` error handler to encode. ``'mbcs'`` supports ``'strict'`` and |
| 1692 | ``'ignore'`` error handlers for decoding, and ``'strict'`` and ``'replace'`` |
| 1693 | for encoding. |
| 1694 | |
| 1695 | On Mac OS X, Python uses ``'utf-8'`` to decode the command line arguments, |
| 1696 | instead of the locale encoding (which is ISO-8859-1 if the ``LANG`` environment |
| 1697 | variable is not set). |
| 1698 | |
| 1699 | By default, tarfile uses ``'utf-8'`` encoding on Windows (instead of |
| 1700 | ``'mbcs'``), and the ``'surrogateescape'`` error handler on all operating |
| 1701 | systems. |
Antoine Pitrou | d305200 | 2010-09-15 15:09:40 +0000 | [diff] [blame] | 1702 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1703 | Also, support was added for *cp720* Arabic DOS encoding (:issue:`1616979`). |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1704 | |
Victor Stinner | 94908bb | 2010-08-18 21:23:25 +0000 | [diff] [blame] | 1705 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1706 | Documentation |
| 1707 | ============= |
| 1708 | |
| 1709 | The documentation continues to be improved. |
| 1710 | |
| 1711 | A table of quick links has been added to the top of lengthy sections such as |
| 1712 | :ref:`built-in-funcs`. In the case of :mod:`itertools`, the links are |
| 1713 | accompanied by tables of cheatsheet-style summaries to provide an overview and |
| 1714 | memory jog without having to read all of the docs. |
| 1715 | |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 1716 | In some cases, the pure Python source code can be a helpful adjunct to the |
| 1717 | documentation, so now many modules now feature quick links to the latest version |
| 1718 | of the source code. For example, the :mod:`functools` module documentation has |
| 1719 | a quick link at the top labeled: **Source code** :source:`Lib/functools.py`. |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1720 | |
| 1721 | The docs now contain more examples and recipes. In particular, :mod:`re` module |
| 1722 | has an extensive section, :ref:`re-examples`. Likewise, the :mod:`itertools` |
| 1723 | module continues to be updated with new :ref:`itertools-recipes`. |
| 1724 | |
Raymond Hettinger | 677e10a | 2010-12-07 06:45:30 +0000 | [diff] [blame] | 1725 | The :mod:`datetime` module now has an auxiliary implementation in pure Python. |
| 1726 | No functionality was changed. This just provides an easier-to-read |
| 1727 | alternate implementation. (Contributed by Alexander Belopolsky.) |
| 1728 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1729 | The unmaintained :file:`Demo` directory has been removed. Some demos were |
| 1730 | integrated into the documentation, some were moved to the :file:`Tools/demo` |
| 1731 | directory, and others were removed altogether. (Contributed by Georg Brandl.) |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1732 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1733 | |
| 1734 | IDLE |
| 1735 | ==== |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1736 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1737 | * The format menu now has an option to clean source files by stripping |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1738 | trailing whitespace. |
| 1739 | |
| 1740 | (Contributed by Raymond Hettinger; :issue:`5150`.) |
| 1741 | |
| 1742 | * IDLE on Mac OS X now works with both Carbon AquaTk and Cocoa AquaTk. |
| 1743 | |
| 1744 | (Contributed by Kevin Walzer, Ned Deily, and Ronald Oussoren; :issue:`6075`.) |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1745 | |
| 1746 | |
| 1747 | Build and C API Changes |
| 1748 | ======================= |
| 1749 | |
| 1750 | Changes to Python's build process and to the C API include: |
| 1751 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1752 | * The *idle*, *pydoc* and *2to3* scripts are now installed with a |
| 1753 | version-specific suffix on ``make altinstall`` (:issue:`10679`). |
| 1754 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1755 | * The C functions that access the Unicode Database now accept and return |
| 1756 | characters from the full Unicode range, even on narrow unicode builds |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1757 | (Py_UNICODE_TOLOWER, Py_UNICODE_ISDECIMAL, and others). A visible difference |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1758 | in Python is that :func:`unicodedata.numeric` now returns the correct value |
| 1759 | for large code points, and :func:`repr` may consider more characters as |
| 1760 | printable. |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1761 | |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1762 | (Reported by Bupjoe Lee and fixed by Amaury Forgeot D'Arc; :issue:`5127`.) |
| 1763 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1764 | * Computed gotos are now enabled by default on supported compilers (which are |
Raymond Hettinger | db9044e | 2010-09-06 01:29:23 +0000 | [diff] [blame] | 1765 | detected by the configure script). They can still be disabled selectively by |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1766 | specifying ``--without-computed-gotos``. |
Raymond Hettinger | 1784ff0 | 2010-09-05 01:00:19 +0000 | [diff] [blame] | 1767 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1768 | (Contributed by Antoine Pitrou; :issue:`9203`.) |
| 1769 | |
Amaury Forgeot d'Arc | feb7307 | 2010-09-12 22:42:57 +0000 | [diff] [blame] | 1770 | * The option ``--with-wctype-functions`` was removed. The built-in unicode |
| 1771 | database is now used for all functions. |
| 1772 | |
| 1773 | (Contributed by Amaury Forgeot D'Arc; :issue:`9210`.) |
| 1774 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1775 | * Hash values are now values of a new type, :c:type:`Py_hash_t`, which is |
| 1776 | defined to be the same size as a pointer. Previously they were of type long, |
| 1777 | which on some 64-bit operating systems is still only 32 bits long. As a |
| 1778 | result of this fix, :class:`set` and :class:`dict` can now hold more than |
| 1779 | ``2**32`` entries on builds with 64-bit pointers (previously, they could grow |
| 1780 | to that size but their performance degraded catastrophically). |
Skip Montanaro | 961aaf5 | 2010-10-17 22:22:24 +0000 | [diff] [blame] | 1781 | |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1782 | (Suggested by Raymond Hettinger and implemented by Benjamin Peterson; |
| 1783 | :issue:`9778`.) |
| 1784 | |
| 1785 | * A new macro :c:macro:`Py_VA_COPY` copies the state of the variable argument |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1786 | list. It is equivalent to C99 *va_copy* but available on all Python platforms |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1787 | (:issue:`2443`). |
| 1788 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1789 | * A new C API function :c:func:`PySys_SetArgvEx` allows an embedded interpreter |
| 1790 | to set :attr:`sys.argv` without also modifying :attr:`sys.path` |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1791 | (:issue:`5753`). |
| 1792 | |
| 1793 | * :c:macro:`PyEval_CallObject` is now only available in macro form. The |
| 1794 | function declaration, which was kept for backwards compatibility reasons, is |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1795 | now removed -- the macro was introduced in 1997 (:issue:`8276`). |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1796 | |
| 1797 | * The is a new function :c:func:`PyLong_AsLongLongAndOverflow` which |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1798 | is analogous to :c:func:`PyLong_AsLongAndOverflow`. They both serve to |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1799 | convert Python :class:`int` into a native fixed-width type while providing |
| 1800 | detection of cases where the conversion won't fit (:issue:`7767`). |
| 1801 | |
| 1802 | * The :c:func:`PyUnicode_CompareWithASCIIString` now returns *not equal* |
| 1803 | if the Python string in *NUL* terminated. |
| 1804 | |
| 1805 | * There is a new function :c:func:`PyErr_NewExceptionWithDoc` that is |
| 1806 | like :c:func:`PyErr_NewException` but allows a docstring to be specified. |
| 1807 | This lets C exceptions have the same self-documenting capabilities as |
| 1808 | their pure Python counterparts (:issue:`7033`). |
| 1809 | |
| 1810 | * When compiled with the ``--with-valgrind`` option, the pymalloc |
| 1811 | allocator will be automatically disabled when running under Valgrind. This |
| 1812 | gives improved memory leak detection when running under Valgrind, while taking |
| 1813 | advantage of pymalloc at other times (:issue:`2422`). |
| 1814 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1815 | * Removed the ``O?`` format from the *PyArg_Parse* functions. The format is no |
Raymond Hettinger | 480ed78 | 2010-12-15 22:07:15 +0000 | [diff] [blame] | 1816 | longer used and it had never been documented (:issue:`8837`). |
| 1817 | |
| 1818 | There were a number of other small changes to the C-API. See the |
| 1819 | :file:`Misc/NEWS` file for a complete list. |
Skip Montanaro | 961aaf5 | 2010-10-17 22:22:24 +0000 | [diff] [blame] | 1820 | |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1821 | |
Raymond Hettinger | f558ddd | 2009-06-28 21:37:08 +0000 | [diff] [blame] | 1822 | Porting to Python 3.2 |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1823 | ===================== |
| 1824 | |
Georg Brandl | da0a211 | 2010-09-05 11:28:33 +0000 | [diff] [blame] | 1825 | This section lists previously described changes and other bugfixes that may |
| 1826 | require changes to your code: |
Raymond Hettinger | 6e6565b | 2009-06-28 20:56:11 +0000 | [diff] [blame] | 1827 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1828 | * The :mod:`configparser` module has a number of clean-ups. The major change is |
| 1829 | to replace the old :class:`ConfigParser` class with long-standing preferred |
| 1830 | alternative :class:`SafeConfigParser`. In addition there are a number of |
| 1831 | smaller incompatibilites: |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1832 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1833 | * The interpolation syntax is now validated on |
| 1834 | :meth:`~configparser.ConfigParser.get` and |
| 1835 | :meth:`~configparser.ConfigParser.set` operations. In the default |
| 1836 | interpolation scheme, only two tokens with percent signs are valid: ``%(name)s`` |
| 1837 | and ``%%``, the latter being an escaped percent sign. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1838 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1839 | * The :meth:`~configparser.ConfigParser.set` and |
| 1840 | :meth:`~configparser.ConfigParser.add_section` methods now verify that |
| 1841 | values are actual strings. Formerly, unsupported types could be introduced |
| 1842 | unintentionally. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1843 | |
Raymond Hettinger | 2b8861f | 2010-12-18 11:20:52 +0000 | [diff] [blame] | 1844 | * Duplicate sections or options from a single source now raise either |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1845 | :exc:`~configparser.DuplicateSectionError` or |
| 1846 | :exc:`~configparser.DuplicateOptionError`. Formerly, duplicates would |
| 1847 | silently overwrite a previous entry. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1848 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1849 | * Inline comments are now disabled by default so now the **;** character |
| 1850 | can be safely used in values. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1851 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1852 | * Comments now can be indented. Consequently, for **;** or **#** to appear at |
| 1853 | 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] | 1854 | keeps comment prefix characters in values from being mistaken as comments. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1855 | |
Raymond Hettinger | d73be67 | 2010-12-18 10:48:26 +0000 | [diff] [blame] | 1856 | * ``""`` is now a valid value and is no longer automatically converted to an |
| 1857 | empty string. For empty strings, use ``"option ="`` in a line. |
Łukasz Langa | 2b38b6c | 2010-12-17 21:57:32 +0000 | [diff] [blame] | 1858 | |
Antoine Pitrou | cd889af | 2010-10-06 21:13:56 +0000 | [diff] [blame] | 1859 | * The :mod:`nntplib` module was reworked extensively, meaning that its APIs |
| 1860 | are often incompatible with the 3.1 APIs. |
| 1861 | |
Raymond Hettinger | 1fa7682 | 2010-12-06 23:31:36 +0000 | [diff] [blame] | 1862 | * :class:`bytearray` objects can no longer be used as filenames; instead, |
| 1863 | they should be converted to :class:`bytes`. |
Victor Stinner | dcb2403 | 2010-04-22 12:08:36 +0000 | [diff] [blame] | 1864 | |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 1865 | * ``PyArg_Parse*()`` functions: |
Victor Stinner | 3dcb5ac | 2010-06-08 22:54:19 +0000 | [diff] [blame] | 1866 | |
Victor Stinner | 25e8ec4 | 2010-06-25 00:02:38 +0000 | [diff] [blame] | 1867 | * "t#" format has been removed: use "s#" or "s*" instead |
| 1868 | * "w" and "w#" formats has been removed: use "w*" instead |
| 1869 | |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 1870 | * The :c:type:`PyCObject` type, deprecated in 3.1, has been removed. To wrap |
| 1871 | 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] | 1872 | 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] | 1873 | information and a less complicated signature for calling a destructor. |
Victor Stinner | 0cbec57 | 2010-09-12 20:32:57 +0000 | [diff] [blame] | 1874 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1875 | * The :func:`sys.setfilesystemencoding` function was removed because |
| 1876 | it had a flawed design. |
Raymond Hettinger | 3fcf002 | 2010-12-08 01:13:53 +0000 | [diff] [blame] | 1877 | |
Raymond Hettinger | e0a9600 | 2010-12-15 17:54:13 +0000 | [diff] [blame] | 1878 | * The :func:`random.seed` function and method now salt string seeds with an |
| 1879 | sha512 hash function. To access the previous version of *seed* in order to |
| 1880 | reproduce Python 3.1 sequences, set the *version* argument to *1*, |
| 1881 | ``random.seed(s, version=1)``. |
Raymond Hettinger | 21ec4bc | 2010-12-10 01:09:01 +0000 | [diff] [blame] | 1882 | |
Raymond Hettinger | 522cc0a | 2010-12-10 01:19:15 +0000 | [diff] [blame] | 1883 | * The previously deprecated :func:`string.maketrans` function has been removed |
Raymond Hettinger | 51e2107 | 2011-01-10 23:38:15 +0000 | [diff] [blame] | 1884 | in favor of the static methods :meth:`bytes.maketrans` and |
Raymond Hettinger | 522cc0a | 2010-12-10 01:19:15 +0000 | [diff] [blame] | 1885 | :meth:`bytearray.maketrans`. This change solves the confusion around which |
| 1886 | types were supported by the :mod:`string` module. Now, :class:`str`, |
| 1887 | :class:`bytes`, and :class:`bytearray` each have their own **maketrans** and |
| 1888 | **translate** methods with intermediate translation tables of the appropriate |
| 1889 | type. |
| 1890 | |
| 1891 | (Contributed by Georg Brandl; :issue:`5675`.) |
| 1892 | |
| 1893 | * The previously deprecated :func:`contextlib.nested` function has been removed |
| 1894 | in favor of a plain :keyword:`with` statement which can accept multiple |
| 1895 | context managers. The latter technique is faster (because it is built-in), |
| 1896 | and it does a better job finalizing multiple context managers when one of them |
| 1897 | raises an exception:: |
| 1898 | |
Raymond Hettinger | 6f0d59b | 2011-01-17 23:10:55 +0000 | [diff] [blame] | 1899 | with open('mylog.txt') as infile, open('a.out', 'w') as outfile: |
| 1900 | for line in infile: |
| 1901 | if '<critical>' in line: |
| 1902 | outfile.write(line) |
Raymond Hettinger | 522cc0a | 2010-12-10 01:19:15 +0000 | [diff] [blame] | 1903 | |
| 1904 | (Contributed by Georg Brandl and Mattias Brändström; |
| 1905 | `appspot issue 53094 <http://codereview.appspot.com/53094>`_.) |
Victor Stinner | da9ec99 | 2010-12-28 13:26:42 +0000 | [diff] [blame] | 1906 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1907 | * :func:`struct.pack` now only allows bytes for the ``s`` string pack code. |
| 1908 | Formerly, it would accept text arguments and implicitly encode them to bytes |
| 1909 | using UTF-8. This was problematic because it made assumptions about the |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1910 | correct encoding and because a variable-length encoding can fail when writing |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1911 | to fixed length segment of a structure. |
Victor Stinner | da9ec99 | 2010-12-28 13:26:42 +0000 | [diff] [blame] | 1912 | |
Raymond Hettinger | 2169ee2 | 2011-01-05 22:27:49 +0000 | [diff] [blame] | 1913 | Code such as ``struct.pack('<6sHHBBB', 'GIF87a', x, y)`` should be rewritten |
| 1914 | with to use bytes instead of text, ``struct.pack('<6sHHBBB', b'GIF87a', x, y)``. |
| 1915 | |
Raymond Hettinger | de2e618 | 2011-01-10 05:40:57 +0000 | [diff] [blame] | 1916 | (Discovered by David Beazley and fixed by Victor Stinner; :issue:`10783`.) |
Raymond Hettinger | e40808a | 2011-01-05 23:00:00 +0000 | [diff] [blame] | 1917 | |
| 1918 | * The :class:`xml.etree.ElementTree` class now raises an |
| 1919 | :exc:`xml.etree.ElementTree.ParseError` when a parse fails. Previously it |
| 1920 | raised a :exc:`xml.parsers.expat.ExpatError`. |
| 1921 | |
| 1922 | * The new, longer :func:`str` value on floats may break doctests which rely on |
| 1923 | the old output format. |
Antoine Pitrou | bcba434 | 2011-01-16 18:29:34 +0000 | [diff] [blame] | 1924 | |
| 1925 | * In :class:`subprocess.Popen`, the default value for *close_fds* is now |
| 1926 | ``True`` under Unix; under Windows, it is ``True`` if the three standard |
| 1927 | streams are set to ``None``, ``False`` otherwise. Previously, *close_fds* |
| 1928 | was always ``False`` by default, which produced difficult to solve bugs |
| 1929 | or race conditions when open file descriptors would leak into the child |
| 1930 | process. |
| 1931 | |
Antoine Pitrou | f7fb762 | 2011-01-16 18:34:09 +0000 | [diff] [blame] | 1932 | * Support for legacy HTTP 0.9 has been removed from :mod:`urllib.request` |
| 1933 | and :mod:`http.client`. Such support is still present on the server side |
| 1934 | (in :mod:`http.server`). |
| 1935 | |
| 1936 | (Contributed by Antoine Pitrou, :issue:`10711`.) |
| 1937 | |
Antoine Pitrou | 2e8ec22 | 2011-01-16 18:41:36 +0000 | [diff] [blame] | 1938 | * SSL sockets in timeout mode now raise :exc:`socket.timeout` when a timeout |
| 1939 | occurs, rather than a generic :exc:`~ssl.SSLError`. |
| 1940 | |
| 1941 | (Contributed by Antoine Pitrou, :issue:`10272`.) |
Antoine Pitrou | ebeb903 | 2011-01-16 18:45:17 +0000 | [diff] [blame] | 1942 | |
| 1943 | * The misleading functions :c:func:`PyEval_AcquireLock()` and |
| 1944 | :c:func:`PyEval_ReleaseLock()` have been officially deprecated. The |
| 1945 | thread-state aware APIs (such as :c:func:`PyEval_SaveThread()` |
| 1946 | and :c:func:`PyEval_RestoreThread()`) should be used instead. |