blob: bf8d1fff532d882cc6243e1418c8f8a5aacbdd58 [file] [log] [blame]
Tim Petersedc99312001-08-22 21:36:50 +00001What's New in Python 2.2a3?
2===========================
3
4Core
5
Tim Petersc6d95812001-08-28 20:56:27 +00006+ An old tokenizer bug allowed floating point literals with an incomplete
7 exponent, such as 1e and 3.1e-. Such literals now raise SyntaxError.
8
Tim Petersedc99312001-08-22 21:36:50 +00009Library
10
11Tools
12
13Build
14
15New platforms
16
17Tests
18
19Windows
20
Tim Peters402d5982001-08-27 06:37:48 +000021+ The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
22 points to command.com (patch from Brian Quinlan).
23
Tim Petersedc99312001-08-22 21:36:50 +000024
Tim Peters20f51a72001-07-21 02:31:40 +000025What's New in Python 2.2a2?
26===========================
27
Martin v. Löwis339d0f72001-08-17 18:39:25 +000028Build
29
Barry Warsaw18b2ecf2001-08-22 20:26:56 +000030- Tim Peters developed a brand new Windows installer using Wise 8.1,
31 generously donated to us by Wise Solutions.
32
Martin v. Löwis339d0f72001-08-17 18:39:25 +000033- configure supports a new option --enable-unicode, with the values
34 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
35 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +000036
Jack Jansen32ce0cd2001-08-21 19:28:20 +000037- A new configure option --enable-framework builds a Mac OS X framework,
38 which "make frameworkinstall" will install. This provides a starting
39 point for more mac-like functionality, join pythonmac-sig@python.org
40 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +000041
Barry Warsaw6f3410d2001-08-22 04:08:41 +000042- The NeXT platform is no longer supported.
43
44- The `new' module is now statically linked.
45
Tim Peters0afb6092001-08-15 06:06:44 +000046Tools
47
48- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +000049 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +000050 the module docstring for details.
51
Tim Peters20f51a72001-07-21 02:31:40 +000052Tests
53
Tim Peters5e824c32001-08-12 22:25:01 +000054- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +000055 platforms, allowing to give clearer test result output. regrtest
56 also has optional --use/-u switch to run normally disabled tests
57 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +000058
Tim Peters20f51a72001-07-21 02:31:40 +000059- Several new tests in the standard test suite, with special thanks to
60 Nick Mathewson.
61
62Core
63
Barry Warsaw6f3410d2001-08-22 04:08:41 +000064- The floor division operator // has been added as outlined in PEP
65 238. The / operator still provides classic division (and will until
66 Python 3.0) unless "from __future__ import division" is included, in
67 which case the / operator will provide true division. The operator
68 module provides truediv() and floordiv() functions. Augmented
69 assignment variants are included, as are the equivalent overloadable
70 methods and C API methods. See the PEP for a full discussion:
71 <http://python.sf.net/peps/pep-0238.html>
72
Tim Peters6cd6a822001-08-17 22:11:27 +000073- Future statements are now effective in simulated interactive shells
74 (like IDLE). This should "just work" by magic, but read Michael
75 Hudson's "Future statements in simulated shells" PEP 264 for full
76 details: <http://python.sf.net/peps/pep-0264.html>.
77
Guido van Rossumf86ddd22001-08-17 21:21:04 +000078- The type/class unification (PEP 252-253) was integrated into the
79 trunk and is not so tentative any more (the exact specification of
80 some features is still tentative). A lot of work has done on fixing
81 bugs and adding robustness and features (performance still has to
82 come a long way).
83
Marc-André Lemburg888fac02001-07-31 14:24:31 +000084- Warnings about a mismatch in the Python API during extension import
85 now use the Python warning framework (which makes it possible to
86 write filters for these warnings).
87
Barry Warsaw9b3be7f2001-08-14 18:35:02 +000088- A function's __dict__ (aka func_dict) will now always be a
89 dictionary. It used to be possible to delete it or set it to None,
90 but now both actions raise TypeErrors. It is still legal to set it
91 to a dictionary object. Getting func.__dict__ before any attributes
92 have been assigned now returns an empty dictionary instead of None.
93
Marc-André Lemburgd6277912001-07-31 14:42:42 +000094Library
95
Tim Peters5e824c32001-08-12 22:25:01 +000096- New class Differ and new functions ndiff() and restore() in difflib.py.
97 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +000098 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +000099
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000100- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
101 value using the minimal quoting required for the value; more
102 reliable than using xml.sax.saxutils.escape() for attribute values.
103
104- Readline completion support for cmd.Cmd was added.
105
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000106- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
107
108- Added function threading.BoundedSemaphore()
109
110- Added Ka-Ping Yee's cgitb.py module.
111
112- The `new' module now exposes the CO_xxx flags.
113
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000114New platforms
115
116C API
117
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000118- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
119 which provide a cross-platform implementations for the
120 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
121 the standard sprintf() and vsprintf() C lib APIs, these versions
122 apply bounds checking on the used buffer which enhances protection
123 against buffer overruns.
124
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000125- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000126 and extensions using different Unicode widths is rendered next to
127 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000128 will result in an ImportError. Unicode extensions writers must make
129 sure to check the Unicode width compatibility in their extensions by
130 using at least one of the mangled Unicode APIs in the extension.
131
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000132- Two new flags METH_NOARGS and METH_O are available in method definition
133 tables to simplify implementation of methods with no arguments and a
134 single untyped argument. Calling such methods is more efficient than
135 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
136 deprecated.
137
Tim Petersc1731372001-08-04 08:12:36 +0000138Windows
139
140- "import module" now compiles module.pyw if it exists and nothing else
141 relevant is found.
142
Tim Peters20f51a72001-07-21 02:31:40 +0000143
Guido van Rossum55a78992001-07-17 17:22:32 +0000144What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000145===========================
146
147Core
Tim Petersa814db52001-05-14 07:05:58 +0000148
Tim Peters6d6c1a32001-08-02 04:15:00 +0000149- TENTATIVELY, a large amount of code implementing much of what's
150 described in PEP 252 (Making Types Look More Like Classes) and PEP
151 253 (Subtyping Built-in Types) was added. This will be released
152 with Python 2.2a1. Documentation will be provided separately
153 through http://www.python.org/2.2/. The purpose of releasing this
154 with Python 2.2a1 is to test backwards compatibility. It is
155 possible, though not likely, that a decision is made not to release
156 this code as part of 2.2 final, if any serious backwards
157 incompapatibilities are found during alpha testing that cannot be
158 repaired.
159
Guido van Rossum55a78992001-07-17 17:22:32 +0000160- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000161 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000162 more 'yield' statements. See PEP 255. Since this adds a new
163 keyword to the language, this feature must be enabled by including a
164 future statement: "from __future__ import generators" (see PEP 236).
165 Generators will become a standard feature in a future release
166 (probably 2.3). Without this future statement, 'yield' remains an
167 ordinary identifier, but a warning is issued each time it is used.
168 (These warnings currently don't conform to the warnings framework of
169 PEP 230; we intend to fix this in 2.2a2.)
170
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000171- The UTF-16 codec was modified to be more RFC compliant. It will now
172 only remove BOM characters at the start of the string and then
173 only if running in native mode (UTF-16-LE and -BE won't remove a
174 leading BMO character).
175
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000176- Strings now have a new method .decode() to complement the already
177 existing .encode() method. These two methods provide direct access
178 to the corresponding decoders and encoders of the registered codecs.
179
180 To enhance the usability of the .encode() method, the special
181 casing of Unicode object return values was dropped (Unicode objects
182 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000183
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000184 Both methods will now return whatever the codec in charge of the
185 requested encoding returns as object, e.g. Unicode codecs will
186 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
187 will return u"äöü"). This enables codec writer to create codecs
188 for various simple to use conversions.
189
190 New codecs were added to demonstrate these new features (the .encode()
191 and .decode() columns indicate the type of the returned objects):
192
193 Name | .encode() | .decode() | Description
194 ----------------------------------------------------------------------
195 uu | string | string | UU codec (e.g. for email)
196 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000197 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000198 zlib | string | string | zlib compression
199 hex | string | string | 2-byte hex codec
200 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
201
Mark Hammond2a0af792001-05-14 03:09:36 +0000202- Some operating systems now support the concept of a default Unicode
203 encoding for file system operations. Notably, Windows supports 'mbcs'
204 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000205 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000206 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000207
208 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000209 functions that return filenames (such as os.listdir()) to return Python
210 string objects pre-encoded using the default file system encoding for
211 the platform. As this encoding is likely to be different from Python's
212 default encoding, converting this name to a Unicode object before passing
213 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000214 would attempt to use its default encoding (generally ASCII) rather than
215 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000216
Tim Petersa814db52001-05-14 07:05:58 +0000217 In general, this change simply removes surprises when working with
218 Unicode and the file system, making these operations work as you expect,
219 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000220 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000221
Tim Peters61dff2b2001-05-08 15:43:37 +0000222- Float (and complex) literals in source code were evaluated to full
223 precision only when running from a .py file; the same code loaded from a
224 .pyc (or .pyo) file could suffer numeric differences starting at about the
225 12th significant decimal digit. For example, on a machine with IEEE-754
226 floating arithmetic,
227
228 x = 9007199254740992.0
229 print long(x)
230
231 printed 9007199254740992 if run directly from .py, but 9007199254740000
232 if from a compiled (.pyc or .pyo) file. This was due to marshal using
233 str(float) instead of repr(float) when building code objects. marshal
234 now uses repr(float) instead, which should reproduce floats to full
235 machine precision (assuming the platform C float<->string I/O conversion
236 functions are of good quality).
237
238 This may cause floating-point results to change in some cases, and
239 usually for the better, but may also cause numerically unstable
240 algorithms to break.
241
Tim Peters2f228e72001-05-13 00:19:31 +0000242- The implementation of dicts suffers fewer collisions, which has speed
243 benefits. However, the order in which dict entries appear in dict.keys(),
244 dict.values() and dict.items() may differ from previous releases for a
245 given dict. Nothing is defined about this order, so no program should
246 rely on it. Nevertheless, it's easy to write test cases that rely on the
247 order by accident, typically because of printing the str() or repr() of a
248 dict to an "expected results" file. See Lib/test/test_support.py's new
249 sortdict(dict) function for a simple way to display a dict in sorted
250 order.
251
Tim Peters7a3bfc32001-06-12 01:22:22 +0000252- Many other small changes to dicts were made, resulting in faster
253 operation along the most common code paths.
254
Guido van Rossum10315822001-05-01 20:54:30 +0000255- Dictionary objects now support the "in" operator: "x in dict" means
256 the same as dict.has_key(x).
257
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000258- The update() method of dictionaries now accepts generic mapping
259 objects. Specifically the argument object must support the .keys()
260 and __getitem__() methods. This allows you to say, for example,
261 {}.update(UserDict())
262
Guido van Rossum10315822001-05-01 20:54:30 +0000263- Iterators were added; this is a generalized way of providing values
264 to a for loop. See PEP 234. There's a new built-in function iter()
265 to return an iterator. There's a new protocol to get the next value
266 from an iterator using the next() method (in Python) or the
267 tp_iternext slot (in C). There's a new protocol to get iterators
268 using the __iter__() method (in Python) or the tp_iter slot (in C).
269 Iterating (i.e. a for loop) over a dictionary generates its keys.
270 Iterating over a file generates its lines.
271
Tim Petersf553f892001-05-01 20:45:31 +0000272- The following functions were generalized to work nicely with iterator
273 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000274 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000275 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
276 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000277 join() method of strings
278 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000279 'x in y' and 'x not in y' (PySequence_Contains() in C API)
280 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000281 right-hand side of assignment statements with multiple targets, such as
282 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000283
Tim Petersd85e1022001-05-11 21:51:48 +0000284- Accessing module attributes is significantly faster (for example,
285 random.random or os.path or yourPythonModule.yourAttribute).
286
Tim Peterse63415e2001-05-08 04:38:29 +0000287- Comparing dictionary objects via == and != is faster, and now works even
288 if the keys and values don't support comparisons other than ==.
289
Tim Peters95bf9392001-05-10 08:32:44 +0000290- Comparing dictionaries in ways other than == and != is slower: there were
291 insecurities in the dict comparison implementation that could cause Python
292 to crash if the element comparison routines for the dict keys and/or
293 values mutated the dicts. Making the code bulletproof slowed it down.
294
Tim Peterseb28ef22001-06-02 05:27:19 +0000295- Collisions in dicts are resolved via a new approach, which can help
296 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000297 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000298 faster now. Thanks to Christian Tismer for pointing out the cause and
299 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000300
Tim Peters52e155e2001-06-16 05:42:57 +0000301- repr() is much faster for large containers (dict, list, tuple).
302
303
Tim Petersa814db52001-05-14 07:05:58 +0000304Library
305
Fred Drake960fdf92001-07-20 18:38:26 +0000306- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
307 were added to the string module. These a locale-indenpendent
308 constants, unlike letters, lowercase, and uppercase. These are now
309 use in appropriate locations in the standard library.
310
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000311- The flags used in dlopen calls can now be configured using
312 sys.setdlopenflags and queried using sys.getdlopenflags.
313
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000314- Fredrik Lundh's xmlrpclib is now a standard library module. This
315 provides full client-side XML-RPC support. In addition,
316 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
317 one asyncore-based). Thanks to Eric Raymond for the documentation.
318
Guido van Rossum643d3912001-07-05 14:46:25 +0000319- The xrange() object is simplified: it no longer supports slicing,
320 repetition, comparisons, efficient 'in' checking, the tolist()
321 method, or the start, stop and step attributes. See PEP 260.
322
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000323- A new function fnmatch.filter to filter lists of file names was added.
324
Barry Warsawffd674d2001-05-22 16:00:10 +0000325- calendar.py uses month and day names based on the current locale.
326
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000327- strop is now *really* obsolete (this was announced before with 1.6),
328 and issues DeprecationWarning when used (except for the four items
329 that are still imported into string.py).
330
Tim Petersa814db52001-05-14 07:05:58 +0000331- Cookie.py now sorts key+value pairs by key in output strings.
332
333- pprint.isrecursive(object) didn't correctly identify recursive objects.
334 Now it does.
335
Tim Peters95b3f782001-05-14 18:39:41 +0000336- pprint functions now much faster for large containers (tuple, list, dict).
337
Tim Peters7b9542a2001-06-10 23:40:19 +0000338- New 'q' and 'Q' format codes in the struct module, corresponding to C
339 types "long long" and "unsigned long long" (on Windows, __int64). In
340 native mode, these can be used only when the platform C compiler supports
341 these types (when HAVE_LONG_LONG is #define'd by the Python config
342 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000343 In standard mode, 'q' and 'Q' are supported on all platforms, and are
344 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000345
Guido van Rossum83213cc2001-06-12 16:48:52 +0000346- The site module installs a new built-in function 'help' that invokes
347 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
348 it displays a message reminding the user to use 'help()' or
349 'help(object)'.
350
Tim Petersa814db52001-05-14 07:05:58 +0000351Tests
352
353- New test_mutants.py runs dict comparisons where the key and value
354 comparison operators mutute the dicts randomly during comparison. This
355 rapidly causes Python to crash under earlier releases (not for the faint
356 of heart: it can also cause Win9x to freeze or reboot!).
357
358- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000359 pprint.isreadable() return sensible results. Also verifies that simple
360 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000361
Tim Peters58e0a8c2001-05-14 22:32:33 +0000362New platforms
363
364- Python should compile and run out of the box using the Borland C
365 compiler (under Windows), thanks to Stephen Hansen.
Tim Petersf553f892001-05-01 20:45:31 +0000366
Tim Peters4324aa32001-05-28 22:30:08 +0000367C API
368
369- Removed the unused last_is_sticky argument from the internal
370 _PyTuple_Resize(). If this affects you, you were cheating.
371
372
Guido van Rossum55a78992001-07-17 17:22:32 +0000373======================================================================
374
375
Guido van Rossumffe13be2001-04-16 18:46:45 +0000376What's New in Python 2.1 (final)?
377=================================
378
379We only changed a few things since the last release candidate, all in
380Python library code:
381
382- A bug in the locale module was fixed that affected locales which
383 define no grouping for numeric formatting.
384
385- A few bugs in the weakref module's implementations of weak
386 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
387 and the test suite was updated to check for these bugs.
388
389- An old bug in the os.path.walk() function (introduced in Python
390 2.0!) was fixed: a non-existent file would cause an exception
391 instead of being ignored.
392
393- Fixed a few bugs in the new symtable module found by Neil Norwitz's
394 PyChecker.
395
396
Guido van Rossum5b08f132001-04-16 02:05:23 +0000397What's New in Python 2.1c2?
398===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000399
Guido van Rossum5b08f132001-04-16 02:05:23 +0000400A flurry of small changes, and one showstopper fixed in the nick of
401time made it necessary to release another release candidate. The list
402here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000403
Guido van Rossum5b08f132001-04-16 02:05:23 +0000404Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000405
Guido van Rossum5b08f132001-04-16 02:05:23 +0000406- Tim discovered a nasty bug in the dictionary code, caused by
407 PyDict_Next() calling dict_resize(), and the GC code's use of
408 PyDict_Next() violating an assumption in dict_items(). This was
409 fixed with considerable amounts of band-aid, but the net effect is a
410 saner and more robust implementation.
411
412- Made a bunch of symbols static that were accidentally global.
413
414Build and Ports
415
416- The setup.py script didn't check for a new enough version of zlib
417 (1.1.3 is needed). Now it does.
418
419- Changed "make clean" target to also remove shared libraries.
420
421- Added a more general warning about the SGI Irix optimizer to README.
422
423Library
424
425- Fix a bug in urllib.basejoin("http://host", "../file.html") which
426 omitted the slash between host and file.html.
427
428- The mailbox module's _Mailbox class contained a completely broken
429 and undocumented seek() method. Ripped it out.
430
431- Fixed a bunch of typos in various library modules (urllib2, smtpd,
432 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
433
434- Fixed a few last-minute bugs in unittest.
435
436Extensions
437
438- Reverted the patch to the OpenSSL code in socketmodule.c to support
439 RAND_status() and the EGD, and the subsequent patch that tried to
440 fix it for pre-0.9.5 versions; the problem with the patch is that on
441 some systems it issues a warning whenever socket is imported, and
442 that's unacceptable.
443
444Tests
445
446- Fixed the pickle tests to work with "import test.test_pickle".
447
448- Tweaked test_locale.py to actually run the test Windows.
449
450- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
451 not "wb" (which is not a valid mode at all).
452
453- Fix pstats browser crashes. Import readline if it exists to make
454 the user interface nicer.
455
456- Add "import thread" to the top of test modules that import the
457 threading module (test_asynchat and test_threadedtempfile). This
458 prevents test failures caused by a broken threading module resulting
459 from a previously caught failed import.
460
461- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
462 needed on some platforms (e.g. Solaris 8) when the tests are run
463 twice in succession.
464
465- Skip rather than fail test_sunaudiodev if no audio device is found.
466
467
468What's New in Python 2.1c1?
469===========================
470
471This list was significantly updated when 2.1c2 was released; the 2.1c1
472release didn't mention most changes that were actually part of 2.1c1:
473
474Legal
475
476- Copyright was assigned to the Python Software Foundation (PSF) and a
477 PSF license (very similar to the CNRI license) was added.
478
479- The CNRI copyright notice was updated to include 2001.
480
481Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000482
Guido van Rossumc9932722001-04-12 02:31:27 +0000483- After a public outcry, assignment to __debug__ is no longer illegal;
484 instead, a warning is issued. It will become illegal in 2.2.
485
Guido van Rossum5b08f132001-04-16 02:05:23 +0000486- Fixed a core dump with "%#x" % 0, and changed the semantics so that
487 "%#x" now always prepends "0x", even if the value is zero.
488
489- Fixed some nits in the bytecode compiler.
490
491- Fixed core dumps when calling certain kinds of non-functions.
492
493- Fixed various core dumps caused by reference count bugs.
494
495Build and Ports
496
497- Use INSTALL_SCRIPT to install script files.
498
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000499- New port: SCO Unixware 7, by Billy G. Allie.
500
Guido van Rossum5b08f132001-04-16 02:05:23 +0000501- Updated RISCOS port.
502
503- Updated BeOS port and notes.
504
505- Various other porting problems resolved.
506
507Library
508
509- The TERMIOS and SOCKET modules are now truly obsolete and
510 unnecessary. Their symbols are incorporated in the termios and
511 socket modules.
512
513- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
514 better tests for pickling.
515
516- threading: make Condition.wait() robust against KeyboardInterrupt.
517
518- zipfile: add support to zipfile to support opening an archive
519 represented by an open file rather than a file name. Fix bug where
520 the archive was not properly closed. Fixed a bug in this bugfix
521 where flush() was called for a read-only file.
522
523- imputil: added an uninstall() method to the ImportManager.
524
525- Canvas: fixed bugs in lower() and tkraise() methods.
526
527- SocketServer: API change (added overridable close_request() method)
528 so that the TCP server can explicitly close the request.
529
530- pstats: Eric Raymond added a simple interactive statistics browser,
531 invoked when the module is run as a script.
532
533- locale: fixed a problem in format().
534
535- webbrowser: made it work when the BROWSER environment variable has a
536 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
537 KDE 2. Fixed some other nits.
538
539- unittest: changes to allow using a different exception than
540 AssertionError, and added a few more function aliases. Some other
541 small changes.
542
543- urllib, urllib2: fixed redirect problems and a coupleof other nits.
544
545- asynchat: fixed a critical bug in asynchat that slipped through the
546 2.1b2 release. Fixed another rare bug.
547
548- Fix some unqualified except: clauses (always a bad code example).
549
550XML
551
552- pyexpat: new API get_version_string().
553
554- Fixed some minidom bugs.
555
556Extensions
557
558- Fixed a core dump in _weakref. Removed the weakref.mapping()
559 function (it adds nothing to the API).
560
561- Rationalized the use of header files in the readline module, to make
562 it compile (albeit with some warnings) with the very recent readline
563 4.2, without breaking for earlier versions.
564
565- Hopefully fixed a buffering problem in linuxaudiodev.
566
567- Attempted a fix to make the OpenSSL support in the socket module
568 work again with pre-0.9.5 versions of OpenSSL.
569
570Tests
571
572- Added a test case for asynchat and asyncore.
573
574- Removed coupling between tests where one test failing could break
575 another.
576
577Tools
578
579- Ping added an interactive help browser to pydoc, fixed some nits
580 in the rest of the pydoc code, and added some features to his
581 inspect module.
582
583- An updated python-mode.el version 4.1 which integrates Ken
584 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
585 much nicer in XEmacs and Emacs. When stepping through your program
586 with pdb, in either the shell window or the *Python* window, the
587 source file and line will be tracked by an arrow. Very cool!
588
589- IDLE: syntax warnings in interactive mode are changed into errors.
590
591- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +0000592 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +0000593
594- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000595
Barry Warsaw11e89c72001-04-11 20:37:57 +0000596
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000597What's New in Python 2.1 beta 2?
598================================
599
Guido van Rossum053ae352001-03-22 14:17:21 +0000600(Unlisted are many fixed bugs, more documentation, etc.)
601
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000602Core language, builtins, and interpreter
603
Guido van Rossum053ae352001-03-22 14:17:21 +0000604- The nested scopes work (enabled by "from __future__ import
605 nested_scopes") is completed; in particular, the future now extends
606 into code executed through exec, eval() and execfile(), and into the
607 interactive interpreter.
608
609- When calling a base class method (e.g. BaseClass.__init__(self)),
610 this is now allowed even if self is not strictly spoken a class
611 instance (e.g. when using metaclasses or the Don Beaudry hook).
612
613- Slice objects are now comparable but not hashable; this prevents
614 dict[:] from being accepted but meaningless.
615
616- Complex division is now calculated using less braindead algorithms.
617 This doesn't change semantics except it's more likely to give useful
618 results in extreme cases. Complex repr() now uses full precision
619 like float repr().
620
621- sgmllib.py now calls handle_decl() for simple <!...> declarations.
622
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000623- It is illegal to assign to the name __debug__, which is set when the
624 interpreter starts. It is effectively a compile-time constant.
625
626- A warning will be issued if a global statement for a variable
627 follows a use or assignment of that variable.
628
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000629Standard library
630
Guido van Rossum053ae352001-03-22 14:17:21 +0000631- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
632 inspired by JUnit), is now part of the standard library. You now
633 have a choice of two testing frameworks: unittest requires you to
634 write testcases as separate code, doctest gathers them from
635 docstrings. Both approaches have their advantages and
636 disadvantages.
637
638- A new module Tix was added, which wraps the Tix extension library
639 for Tk. With that module, it is not necessary to statically link
640 Tix with _tkinter, since Tix will be loaded with Tcl's "package
641 require" command. See Demo/tix/.
642
643- tzparse.py is now obsolete.
644
645- In gzip.py, the seek() and tell() methods are removed -- they were
646 non-functional anyway, and it's better if callers can test for their
647 existence with hasattr().
648
649Python/C API
650
651- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
652 that's already in the dictionary during a PyDict_Next() iteration.
653 This used to fail occasionally when a dictionary resize operation
654 could be triggered that would rehash all the keys. All other
655 modifications to the dictionary are still off-limits during a
656 PyDict_Next() iteration!
657
658- New extended APIs related to passing compiler variables around.
659
660- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
661 implement isinstance() and issubclass().
662
663- Py_BuildValue() now has a "D" conversion to create a Python complex
664 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000665
Fred Drake4e262a92001-03-22 18:26:47 +0000666- Extensions types which support weak references must now set the
667 field allocated for the weak reference machinery to NULL themselves;
668 this is done to avoid the cost of checking each object for having a
669 weakly referencable type in PyObject_INIT(), since most types are
670 not weakly referencable.
671
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000672- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
673 free variables and cell variables to and from the frame's f_locals.
674
675- Variants of several functions defined in pythonrun.h have been added
676 to support the nested_scopes future statement. The variants all end
677 in Flags and take an extra argument, a PyCompilerFlags *; examples:
678 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
679 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +0000680 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000681
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000682Distutils
683
684- the sdist command now writes a PKG-INFO file, as described in PEP 241,
685 into the release tree.
686
Tim Peters0e57abf2001-05-02 07:39:38 +0000687- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000688 (an uninstaller, more customization of the installer's display)
689
690- from Jack Jansen: added Mac-specific code to generate a dialog for
691 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +0000692 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000693 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +0000694
695- added 'platforms' and 'keywords' to the set of metadata that can be
696 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000697
698- applied patches from Jason Tishler to make the compiler class work with
699 Cygwin.
700
701
Tim Peters2fe289a2001-03-01 22:19:38 +0000702What's New in Python 2.1 beta 1?
703================================
Tim Petersd66595f2001-02-04 03:09:53 +0000704
705Core language, builtins, and interpreter
706
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000707- Following an outcry from the community about the amount of code
708 broken by the nested scopes feature introduced in 2.1a2, we decided
709 to make this feature optional, and to wait until Python 2.2 (or at
710 least 6 months) to make it standard. The option can be enabled on a
711 per-module basis by adding "from __future__ import nested_scopes" at
712 the beginning of a module (before any other statements, but after
713 comments and an optional docstring). See PEP 236 (Back to the
714 __future__) for a description of the __future__ statement. PEP 227
715 (Statically Nested Scopes) has been updated to reflect this change,
716 and to clarify the semantics in a number of endcases.
717
718- The nested scopes code, when enabled, has been hardened, and most
719 bugs and memory leaks in it have been fixed.
720
721- Compile-time warnings are now generated for a number of conditions
722 that will break or change in meaning when nested scopes are enabled:
723
724 - Using "from...import *" or "exec" without in-clause in a function
725 scope that also defines a lambda or nested function with one or
726 more free (non-local) variables. The presence of the import* or
727 bare exec makes it impossible for the compiler to determine the
728 exact set of local variables in the outer scope, which makes it
729 impossible to determine the bindings for free variables in the
730 inner scope. To avoid the warning about import *, change it into
731 an import of explicitly name object, or move the import* statement
732 to the global scope; to avoid the warning about bare exec, use
733 exec...in... (a good idea anyway -- there's a possibility that
734 bare exec will be deprecated in the future).
735
736 - Use of a global variable in a nested scope with the same name as a
737 local variable in a surrounding scope. This will change in
738 meaning with nested scopes: the name in the inner scope will
739 reference the variable in the outer scope rather than the global
740 of the same name. To avoid the warning, either rename the outer
741 variable, or use a global statement in the inner function.
742
Neil Schemenauera35c6882001-02-27 04:45:05 +0000743- An optional object allocator has been included. This allocator is
744 optimized for Python objects and should be faster and use less memory
745 than the standard system allocator. It is not enabled by default
746 because of possible thread safety problems. The allocator is only
747 protected by the Python interpreter lock and it is possible that some
748 extension modules require a thread safe allocator. The object
749 allocator can be enabled by providing the "--with-pymalloc" option to
750 configure.
751
Tim Petersd66595f2001-02-04 03:09:53 +0000752Standard library
753
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000754- pyexpat now detects the expat version if expat.h defines it. A
755 number of additional handlers are provided, which are only available
756 since expat 1.95. In addition, the methods SetParamEntityParsing and
757 GetInputContext of Parser objects are available with 1.95.x
758 only. Parser objects now provide the ordered_attributes and
759 specified_attributes attributes. A new module expat.model was added,
760 which offers a number of additional constants if 1.95.x is used.
761
762- xml.dom offers the new functions registerDOMImplementation and
763 getDOMImplementation.
764
765- xml.dom.minidom offers a toprettyxml method. A number of DOM
766 conformance issues have been resolved. In particular, Element now
767 has an hasAttributes method, and the handling of namespaces was
768 improved.
769
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000770- Ka-Ping Yee contributed two new modules: inspect.py, a module for
771 getting information about live Python code, and pydoc.py, a module
772 for interactively converting docstrings to HTML or text.
773 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000774 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000775 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
776 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000777
Tim Peters1eff7962001-03-01 02:31:33 +0000778- New library module difflib.py, primarily packaging the SequenceMatcher
779 class at the heart of the popular ndiff.py file-comparison tool.
780
781- doctest.py (a framework for verifying Python code examples in docstrings)
782 is now part of the std library.
783
Tim Petersd66595f2001-02-04 03:09:53 +0000784Windows changes
785
Guido van Rossume3955a82001-03-02 14:05:59 +0000786- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
787 small GUI that lets you browse the module docstrings using your
788 default web browser.
789
Tim Peters1eff7962001-03-01 02:31:33 +0000790- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
791 Platforms) is implemented. See
792
793 http://python.sourceforge.net/peps/pep-0235.html
794
795 for full details, especially the "Current Lower-Left Semantics" section.
796 The new Windows import rules are simpler than before:
797
798 A. If the PYTHONCASEOK environment variable exists, same as
799 before: silently accept the first case-insensitive match of any
800 kind; raise ImportError if none found.
801
802 B. Else search sys.path for the first case-sensitive match; raise
803 ImportError if none found.
804
805 The same rules have been implented on other platforms with case-
806 insensitive but case-preserving filesystems too (including Cygwin, and
807 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000808
Tim Peters25a9ce32001-02-19 07:06:36 +0000809- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
810 what it's supposed to do (and does do under NT and 2000) via direct
811 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000812 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000813 all Win9x systems before.
814
Tim Peters1eff7962001-03-01 02:31:33 +0000815- Build: Subproject _test (effectively) renamed to _testcapi.
816
Tim Peters2fe289a2001-03-01 22:19:38 +0000817New platforms
818
819- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
820 Thanks to Steven Majewski!
821
822- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
823 Tishler!
824
Guido van Rossum9089b272001-03-02 06:49:50 +0000825- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
826 Schwertberger! See RISCOS/README for more information -- it seems
827 that because of the bizarre filename conventions on RISCOS, no port
828 to that platform is easy. Note that the new variable os.endsep is
829 silently supported in order to make life easier on this platform,
830 but we don't advertise it because it's not worth for most folks to
831 care about RISCOS portability.
832
Tim Peters25a9ce32001-02-19 07:06:36 +0000833
Tim Petersd7b5e882001-01-25 03:36:26 +0000834What's New in Python 2.1 alpha 2?
835=================================
Tim Peters40ead762001-01-27 05:35:26 +0000836
Tim Petersd7b5e882001-01-25 03:36:26 +0000837Core language, builtins, and interpreter
838
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000839- Scopes nest. If a name is used in a function or class, but is not
840 local, the definition in the nearest enclosing function scope will
841 be used. One consequence of this change is that lambda statements
842 could reference variables in the namespaces where the lambda is
843 defined. In some unusual cases, this change will break code.
844
845 In all previous version of Python, names were resolved in exactly
846 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000847 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000848 function A is defined within a function B, the names bound in B are
849 not visible in A. The new rules make names bound in B visible in A,
850 unless A contains a name binding that hides the binding in B.
851
852 Section 4.1 of the reference manual describes the new scoping rules
853 in detail. The test script in Lib/test/test_scope.py demonstrates
854 some of the effects of the change.
855
856 The new rules will cause existing code to break if it defines nested
857 functions where an outer function has local variables with the same
858 name as globals or builtins used by the inner function. Example:
859
860 def munge(str):
861 def helper(x):
862 return str(x)
863 if type(str) != type(''):
864 str = helper(str)
865 return str.strip()
866
867 Under the old rules, the name str in helper() is bound to the
868 builtin function str(). Under the new rules, it will be bound to
869 the argument named str and an error will occur when helper() is
870 called.
871
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000872- The compiler will report a SyntaxError if "from ... import *" occurs
873 in a function or class scope. The language reference has documented
874 that this case is illegal, but the compiler never checked for it.
875 The recent introduction of nested scope makes the meaning of this
876 form of name binding ambiguous. In a future release, the compiler
877 may allow this form when there is no possibility of ambiguity.
878
Tim Peters40ead762001-01-27 05:35:26 +0000879- repr(string) is easier to read, now using hex escapes instead of octal,
880 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
881
882 >>> "\texample \r\n" + chr(0) + chr(255)
883 '\texample \r\n\x00\xff' # in 2.1
884 '\011example \015\012\000\377' # in 2.0
885
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000886- Functions are now compared and hashed by identity, not by value, since
887 the func_code attribute is writable.
888
Fred Drakefb9d7122001-02-01 20:00:40 +0000889- Weak references (PEP 205) have been added. This involves a few
890 changes in the core, an extension module (_weakref), and a Python
891 module (weakref). The weakref module is the public interface. It
892 includes support for "explicit" weak references, proxy objects, and
893 mappings with weakly held values.
894
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000895- A 'continue' statement can now appear in a try block within the body
896 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000897 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000898
Tim Petersd7b5e882001-01-25 03:36:26 +0000899Standard library
900
Barry Warsaw30dbd142001-01-31 22:14:01 +0000901- mailbox.py now has a new class, PortableUnixMailbox which is
902 identical to UnixMailbox but uses a more portable scheme for
903 determining From_ separators. Also, the constructors for all the
904 classes in this module have a new optional `factory' argument, which
905 is a callable used when new message classes must be instantiated by
906 the next() method.
907
Tim Petersd7b5e882001-01-25 03:36:26 +0000908- random.py is now self-contained, and offers all the functionality of
909 the now-deprecated whrandom.py. See the docs for details. random.py
910 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000911 and restoring the internal state of the generator; and jumpahead(n),
912 for quickly forcing the internal state to be the same as if n calls to
913 random() had been made. The latter is particularly useful for multi-
914 threaded programs, creating one instance of the random.Random() class for
915 each thread, then using .jumpahead() to force each instance to use a
916 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000917
Tim Peters0de88fc2001-02-01 04:59:18 +0000918- random.py's seed() function is new. For bit-for-bit compatibility with
919 prior releases, use the whseed function instead. The new seed function
920 addresses two problems: (1) The old function couldn't produce more than
921 about 2**24 distinct internal states; the new one about 2**45 (the best
922 that can be done in the Wichmann-Hill generator). (2) The old function
923 sometimes produced identical internal states when passed distinct
924 integers, and there was no simple way to predict when that would happen;
925 the new one guarantees to produce distinct internal states for all
926 arguments in [0, 27814431486576L).
927
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000928- The socket module now supports raw packets on Linux. The socket
929 family is AF_PACKET.
930
Tim Peters9ea17ac2001-02-02 05:57:15 +0000931- test_capi.py is a start at running tests of the Python C API. The tests
932 are implemented by the new Modules/_testmodule.c.
933
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000934- A new extension module, _symtable, provides provisional access to the
935 internal symbol table used by the Python compiler. A higher-level
936 interface will be added on top of _symtable in a future release.
937
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000938- Removed the obsolete soundex module.
939
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000940- xml.dom.minidom now uses the standard DOM exceptions. Node supports
941 the isSameNode method; NamedNodeMap the get method.
942
943- xml.sax.expatreader supports the lexical handler property; it
944 generates comment, startCDATA, and endCDATA events.
945
Tim Petersee826f82001-01-31 19:39:44 +0000946Windows changes
947
948- Build procedure: the zlib project is built in a different way that
949 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000950 the zlib binary used. See PCbuild\readme.txt for details. Your old
951 zlib-related directories can be deleted; you'll need to download fresh
952 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000953
Tim Peters9ea17ac2001-02-02 05:57:15 +0000954- Build: New subproject _test for the benefit of test_capi.py (see above).
955
Tim Petersb16c56f2001-02-02 21:24:51 +0000956- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
957 interface to some Python compiler internals).
958
959- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000960 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000961
Tim Petersa3a3a032000-11-30 05:22:44 +0000962What's New in Python 2.1 alpha 1?
963=================================
964
965Core language, builtins, and interpreter
966
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000967- There is a new Unicode companion to the PyObject_Str() API
968 called PyObject_Unicode(). It behaves in the same way as the
969 former, but assures that the returned value is an Unicode object
970 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000971
Guido van Rossumf98eda02001-01-17 15:54:45 +0000972- The comparison operators support "rich comparison overloading" (PEP
973 207). C extension types can provide a rich comparison function in
974 the new tp_richcompare slot in the type object. The cmp() function
975 and the C function PyObject_Compare() first try the new rich
976 comparison operators before trying the old 3-way comparison. There
977 is also a new C API PyObject_RichCompare() (which also falls back on
978 the old 3-way comparison, but does not constrain the outcome of the
979 rich comparison to a Boolean result).
980
981 The rich comparison function takes two objects (at least one of
982 which is guaranteed to have the type that provided the function) and
983 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
984 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
985 object, which may be NotImplemented (in which case the tp_compare
986 slot function is used as a fallback, if defined).
987
988 Classes can overload individual comparison operators by defining one
989 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000990 __ge__. There are no explicit "reflected argument" versions of
991 these; instead, __lt__ and __gt__ are each other's reflection,
992 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
993 reflection (similar at the C level). No other implications are
994 made; in particular, Python does not assume that == is the Boolean
995 inverse of !=, or that < is the Boolean inverse of >=. This makes
996 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000997
998 Classes or types that want to implement (in)equality tests but not
999 the ordering operators (i.e. unordered types) should implement ==
1000 and !=, and raise an error for the ordering operators.
1001
Guido van Rossuma88479f2001-01-18 14:28:08 +00001002 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +00001003 Boolean; e.g. a matrix type might want to return a matrix of bits
1004 for A < B, giving elementwise comparisons. Such types should ensure
1005 that any interpretation of their value in a Boolean context raises
1006 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
1007 at the C level) to always raise an exception.
1008
Guido van Rossuma88479f2001-01-18 14:28:08 +00001009- Complex numbers use rich comparisons to define == and != but raise
1010 an exception for <, <=, > and >=. Unfortunately, this also means
1011 that cmp() of two complex numbers raises an exception when the two
1012 numbers differ. Since it is not mathematically meaningful to compare
1013 complex numbers except for equality, I hope that this doesn't break
1014 too much code.
1015
Tim Peters3389f192001-02-18 08:48:49 +00001016- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +00001017 not defined by the language, other than that it's arbitrary but
1018 consistent (see the Reference Manual). An implementation detail changed
1019 in 2.1a1 such that None now compares less than any other object. Code
1020 relying on this new behavior (like code that relied on the previous
1021 behavior) does so at its own risk.
1022
Barry Warsaw573b5412001-01-15 20:43:18 +00001023- Functions and methods now support getting and setting arbitrarily
1024 named attributes (PEP 232). Functions have a new __dict__
1025 (a.k.a. func_dict) which hold the function attributes. Methods get
1026 and set attributes on their underlying im_func. It is a TypeError
1027 to set an attribute on a bound method.
1028
Guido van Rossum051e3352001-01-15 19:11:10 +00001029- The xrange() object implementation has been improved so that
1030 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1031 limitation that in this case len(xrange(sys.maxint)) can't be
1032 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1033 work fine as long as the index i doesn't actually reach 2**31.
1034 (Python uses regular ints for sequence and string indices; fixing
1035 that is much more work.)
1036
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001037- Two changes to from...import:
1038
Guido van Rossumba381232001-02-03 15:06:40 +00001039 1) "from M import X" now works even if (after loading module M)
1040 sys.modules['M'] is not a real module; it's basically a getattr()
1041 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001042
1043 2) "from M import *" now looks for M.__all__ to decide which names to
1044 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1045 filters out names starting with '_' as before. Whether or not
1046 __all__ exists, there's no restriction on the type of M.
1047
Guido van Rossumf61f1662001-01-10 20:13:55 +00001048- File objects have a new method, xreadlines(). This is the fastest
1049 way to iterate over all lines in a file:
1050
1051 for line in file.xreadlines():
1052 ...do something to line...
1053
1054 See the xreadlines module (mentioned below) for how to do this for
1055 other file-like objects.
1056
1057- Even if you don't use file.xreadlines(), you may expect a speedup on
1058 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001059 quite a bit in platform-specific ways: on systems (like Linux) that
1060 support flockfile(), getc_unlocked(), and funlockfile(), those are
1061 used by default. On systems (like Windows) without getc_unlocked(),
1062 a complicated (but still thread-safe) method using fgets() is used by
1063 default.
1064
Tim Petersd52269b2001-01-25 06:23:18 +00001065 You can force use of the fgets() method by #define'ing
1066 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001067 getc_unlocked()).
1068
Tim Petersd52269b2001-01-25 06:23:18 +00001069 You can force fgets() not to be used by #define'ing
1070 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001071 test_bufio.py fails -- and let us know if it does!).
1072
1073- In addition, the fileinput module, while still slower than the other
1074 methods on most platforms, has been sped up too, by using
1075 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001076
1077- Support for run-time warnings has been added, including a new
1078 command line option (-W) to specify the disposition of warnings.
1079 See the description of the warnings module below.
1080
1081- Extensive changes have been made to the coercion code. This mostly
1082 affects extension modules (which can now implement mixed-type
1083 numerical operators without having to use coercion), but
1084 occasionally, in boundary cases the coercion semantics have changed
1085 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001086 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001087 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001088 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001089
Guido van Rossumf98eda02001-01-17 15:54:45 +00001090- In connection with the coercion changes, a new built-in singleton
1091 object, NotImplemented is defined. This can be returned for
1092 operations that wish to indicate they are not implemented for a
1093 particular combination of arguments. From C, this is
1094 Py_NotImplemented.
1095
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001096- The interpreter accepts now bytecode files on the command line even
1097 if they do not have a .pyc or .pyo extension. On Linux, after executing
1098
Martin v. Löwise214baa2001-02-04 22:37:56 +00001099import imp,sys,string
1100magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1101reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1102open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001103
1104 any byte code file can be used as an executable (i.e. as an argument
1105 to execve(2)).
1106
Tim Peters9940b802000-12-01 07:59:35 +00001107- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001108 character. In 1.6 and earlier, they never produced a sign,
1109 and raised an error if the value of the long was too large
1110 to fit in a Python int. In 2.0, they produced a sign if and
1111 only if too large to fit in an int. This was inconsistent
1112 across platforms (because the size of an int varies across
1113 platforms), and inconsistent with hex() and oct(). Example:
1114
1115 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001116 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001117 'ffffffbe' # in 2.0 and before, on 32-bit machines
1118 >>> hex(-0x42L)
1119 '-0x42L' # in all versions of Python
1120
Tim Peters9940b802000-12-01 07:59:35 +00001121 The behavior of %d formats for negative Python longs remains
1122 the same as in 2.0 (although in 1.6 and before, they raised
1123 an error if the long didn't fit in a Python int).
1124
1125 %u formats don't make sense for Python longs, but are allowed
1126 and treated the same as %d in 2.1. In 2.0, a negative long
1127 formatted via %u produced a sign if and only if too large to
1128 fit in an int. In 1.6 and earlier, a negative long formatted
1129 via %u raised an error if it was too big to fit in an int.
1130
Guido van Rossum3661d392000-12-12 22:10:31 +00001131- Dictionary objects have an odd new method, popitem(). This removes
1132 an arbitrary item from the dictionary and returns it (in the form of
1133 a (key, value) pair). This can be useful for algorithms that use a
1134 dictionary as a bag of "to do" items and repeatedly need to pick one
1135 item. Such algorithms normally end up running in quadratic time;
1136 using popitem() they can usually be made to run in linear time.
1137
Tim Peters36cdad12000-12-29 02:06:45 +00001138Standard library
1139
Thomas Woutersfe385252001-01-19 23:16:56 +00001140- In the time module, the time argument to the functions strftime,
1141 localtime, gmtime, asctime and ctime is now optional, defaulting to
1142 the current time (in the local timezone).
1143
Guido van Rossumda91f222001-01-15 16:36:08 +00001144- The ftplib module now defaults to passive mode, which is deemed a
1145 more useful default given that clients are often inside firewalls
1146 these days. Note that this could break if ftplib is used to connect
1147 to a *server* that is inside a firewall, from outside; this is
1148 expected to be a very rare situation. To fix that, you can call
1149 ftp.set_pasv(0).
1150
Martin v. Löwis10a27872001-01-13 09:54:41 +00001151- The module site now treats .pth files not only for path configuration,
1152 but also supports extensions to the initialization code: Lines starting
1153 with import are executed.
1154
Guido van Rossumf61f1662001-01-10 20:13:55 +00001155- There's a new module, warnings, which implements a mechanism for
1156 issuing and filtering warnings. There are some new built-in
1157 exceptions that serve as warning categories, and a new command line
1158 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1159 turns warnings into errors). warnings.warn(message[, category])
1160 issues a warning message; this can also be called from C as
1161 PyErr_Warn(category, message).
1162
1163- A new module xreadlines was added. This exports a single factory
1164 function, xreadlines(). The intention is that this code is the
1165 absolutely fastest way to iterate over all lines in an open
1166 file(-like) object:
1167
1168 import xreadlines
1169 for line in xreadlines.xreadlines(file):
1170 ...do something to line...
1171
1172 This is equivalent to the previous the speed record holder using
1173 file.readlines(sizehint). Note that if file is a real file object
1174 (as opposed to a file-like object), this is equivalent:
1175
1176 for line in file.xreadlines():
1177 ...do something to line...
1178
Tim Peters36cdad12000-12-29 02:06:45 +00001179- The bisect module has new functions bisect_left, insort_left,
1180 bisect_right and insort_right. The old names bisect and insort
1181 are now aliases for bisect_right and insort_right. XXX_right
1182 and XXX_left methods differ in what happens when the new element
1183 compares equal to one or more elements already in the list: the
1184 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001185 right. Code that doesn't care where equal elements end up should
1186 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001187
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001188- The new curses.panel module wraps the panel library that forms part
1189 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1190
Guido van Rossumf61f1662001-01-10 20:13:55 +00001191- The SocketServer module now sets the allow_reuse_address flag by
1192 default in the TCPServer class.
1193
1194- A new function, sys._getframe(), returns the stack frame pointer of
1195 the caller. This is intended only as a building block for
1196 higher-level mechanisms such as string interpolation.
1197
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001198- The pyexpat module supports a number of new handlers, which are
1199 available only in expat 1.2. If invocation of a callback fails, it
1200 will report an additional frame in the traceback. Parser objects
1201 participate now in garbage collection. If expat reports an unknown
1202 encoding, pyexpat will try to use a Python codec; that works only
1203 for single-byte charsets. The parser type objects is exposed as
1204 XMLParserObject.
1205
1206- xml.dom now offers standard definitions for symbolic node type and
1207 exception code constants, and a hierarchy of DOM exceptions. minidom
1208 was adjusted to use them.
1209
1210- The conformance of xml.dom.minidom to the DOM specification was
1211 improved. It detects a number of additional error cases; the
1212 previous/next relationship works even when the tree is modified;
1213 Node supports the normalize() method; NamedNodeMap, DocumentType and
1214 DOMImplementation classes were added; Element supports the
1215 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1216 method.
1217
Guido van Rossumf61f1662001-01-10 20:13:55 +00001218Build issues
1219
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001220- For Unix (and Unix-compatible) builds, configuration and building of
1221 extension modules is now greatly automated. Rather than having to
1222 edit the Modules/Setup file to indicate which modules should be
1223 built and where their include files and libraries are, a
1224 distutils-based setup.py script now takes care of building most
1225 extension modules. All extension modules built this way are built
1226 as shared libraries. Only a few modules that must be linked
1227 statically are still listed in the Setup file; you won't need to
1228 edit their configuration.
1229
1230- Python should now build out of the box on Cygwin. If it doesn't,
1231 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001232
1233- Python now always uses its own (renamed) implementation of getopt()
1234 -- there's too much variation among C library getopt()
1235 implementations.
1236
1237- C++ compilers are better supported; the CXX macro is always set to a
1238 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001239
Tim Petersd92dfe02000-12-12 01:18:41 +00001240Windows changes
1241
1242- select module: By default under Windows, a select() call
1243 can specify no more than 64 sockets. Python now boosts
1244 this Microsoft default to 512. If you need even more than
1245 that, see the MS docs (you'll need to #define FD_SETSIZE
1246 and recompile Python from source).
1247
Guido van Rossumf61f1662001-01-10 20:13:55 +00001248- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1249 subdirectory is no more!
1250
Tim Petersa3a3a032000-11-30 05:22:44 +00001251
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001252What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001253=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001254
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001255Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001256changes are in the file HISTORY. If you are making the jump directly
1257from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1258HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001259
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001260Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1261the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1262http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001263
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001264--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001265
1266======================================================================
1267
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001268What's new in 2.0 (since release candidate 1)?
1269==============================================
1270
1271Standard library
1272
1273- The copy_reg module was modified to clarify its intended use: to
1274 register pickle support for extension types, not for classes.
1275 pickle() will raise a TypeError if it is passed a class.
1276
1277- Fixed a bug in gettext's "normalize and expand" code that prevented
1278 it from finding an existing .mo file.
1279
1280- Restored support for HTTP/0.9 servers in httplib.
1281
Tim Peters989b7b92000-10-16 20:24:53 +00001282- The math module was changed to stop raising OverflowError in case of
1283 underflow, and return 0 instead in underflow cases. Whether Python
1284 used to raise OverflowError in case of underflow was platform-
1285 dependent (it did when the platform math library set errno to ERANGE
1286 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001287
1288- Fixed a bug in StringIO that occurred when the file position was not
1289 at the end of the file and write() was called with enough data to
1290 extend past the end of the file.
1291
1292- Fixed a bug that caused Tkinter error messages to get lost on
1293 Windows. The bug was fixed by replacing direct use of
1294 interp->result with Tcl_GetStringResult(interp).
1295
1296- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1297 redirect response.
1298
1299- Several changes were made to distutils: Some debugging code was
1300 removed from util. Fixed the installer used when an external zip
1301 program (like WinZip) is not found; the source code for this
1302 installer is in Misc/distutils. check_lib() was modified to behave
1303 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1304 test for whether installed modules are on sys.path was changed to
1305 use both normcase() and normpath().
1306
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001307- Several minor bugs were fixed in the xml package (the minidom,
1308 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001309
1310- The regression test driver (regrtest.py) behavior when invoked with
1311 -l changed: It now reports a count of objects that are recognized as
1312 garbage but not freed by the garbage collector.
1313
Tim Peters989b7b92000-10-16 20:24:53 +00001314- The regression test for the math module was changed to test
1315 exceptional behavior when the test is run in verbose mode. Python
1316 cannot yet guarantee consistent exception behavior across platforms,
1317 so the exception part of test_math is run only in verbose mode, and
1318 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001319
1320Internals
1321
1322- PyOS_CheckStack() has been disabled on Win64, where it caused
1323 test_sre to fail.
1324
1325Build issues
1326
1327- Changed compiler flags, so that gcc is always invoked with -Wall and
1328 -Wstrict-prototypes. Users compiling Python with GCC should see
1329 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001330 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001331 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001332
Tim Petersa3a3a032000-11-30 05:22:44 +00001333- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001334
1335Tools and other miscellany
1336
1337- The compiler in Tools/compiler was updated to support the new
1338 language features introduced in 2.0: extended print statement, list
1339 comprehensions, and augmented assignments. The new compiler should
1340 also be backwards compatible with Python 1.5.2; the compiler will
1341 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001342 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001343
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001344What's new in 2.0 release candidate 1 (since beta 2)?
1345=====================================================
1346
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001347What is release candidate 1?
1348
1349We believe that release candidate 1 will fix all known bugs that we
1350intend to fix for the 2.0 final release. This release should be a bit
1351more stable than the previous betas. We would like to see even more
1352widespread testing before the final release, so we are producing this
1353release candidate. The final release will be exactly the same unless
1354any show-stopping (or brown bag) bugs are found by testers of the
1355release candidate.
1356
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001357All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001358to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001359
1360Core language, builtins, and interpreter
1361
1362- A bug that caused crashes when __coerce__ was used with augmented
1363 assignment, e.g. +=, was fixed.
1364
1365- Raise ZeroDivisionError when raising zero to a negative number,
1366 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1367 power operator and the result of math.pow(0.0, -2.0) will vary by
1368 platform. On Linux, it raises a ValueError.
1369
1370- A bug in Unicode string interpolation was fixed that occasionally
1371 caused errors with formats including "%%". For example, the
1372 following expression "%% %s" % u"abc" no longer raises a TypeError.
1373
1374- Compilation of deeply nested expressions raises MemoryError instead
1375 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1376
1377- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1378 rendering them useless. They are now written in binary mode again.
1379
1380Standard library
1381
1382- Keyword arguments are now accepted for most pattern and match object
1383 methods in SRE, the standard regular expression engine.
1384
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001385- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001386 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001387
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001388- Several bugs in the Unicode handling and error handling in _tkinter
1389 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001390
1391- Fix memory management errors in Merge() and Tkapp_Call() routines.
1392
1393- Several changes were made to cStringIO to make it compatible with
1394 the file-like object interface and with StringIO. If operations are
1395 performed on a closed object, an exception is raised. The truncate
1396 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001397 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001398
1399- There were many changes made to the linuxaudiodev module and its
1400 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001401 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001402
1403 Note that this module is named poorly, because it should work
1404 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001405 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001406
1407 The module now raises exceptions when errors occur instead of
1408 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1409 audio) and defines a getptr() method that calls the
1410 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1411
1412- The library_version attribute, introduced in an earlier beta, was
1413 removed because it can not be supported with early versions of the C
1414 readline library, which provides no way to determine the version at
1415 compile-time.
1416
1417- The binascii module is now enabled on Win64.
1418
Tim Peters46446d62000-10-09 21:19:31 +00001419- tokenize.py no longer suffers "recursion depth" errors when parsing
1420 programs with very long string literals.
1421
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001422Internals
1423
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001424- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001425 which is called when the interpreter starts up to determine where
1426 the standard library is installed. These vulnerabilities affect all
1427 previous versions of Python and can be exploited by setting very
1428 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1429 setuid Python script, although use of the wrapper in
1430 Misc/setuid-prog.c will eliminate the vulnerability.
1431
1432- Fixed garbage collection bugs in instance creation that were
1433 triggered when errors occurred during initialization. The solution,
1434 applied in cPickle and in PyInstance_New(), is to call
1435 PyObject_GC_Init() after the initialization of the object's
1436 container attributes is complete.
1437
1438- pyexpat adds definitions of PyModule_AddStringConstant and
1439 PyModule_AddObject if the Python version is less than 2.0, which
1440 provides compatibility with PyXML on Python 1.5.2.
1441
1442- If the platform has a bogus definition for LONG_BIT (the number of
1443 bits in a long), an error will be reported at compile time.
1444
1445- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1446 collection crashes and possibly other, unreported crashes.
1447
1448- Fixed a memory leak in _PyUnicode_Fini().
1449
1450Build issues
1451
1452- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001453 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001454 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001455
1456- The mmap.PAGESIZE constant is now initialized using sysconf when
1457 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1458
1459- The md5 file should now compile on all platforms.
1460
1461- The select module now compiles on platforms that do not define
1462 POLLRDNORM and related constants.
1463
1464- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001465 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001466
Jeremy Hylton10921202000-10-09 18:34:12 +00001467- BeOS: A number of changes were made to the build and installation
1468 process. ar-fake now operates on a directory of object files.
1469 dl_export.h is gone, and its macros now appear on the mwcc command
1470 line during build on PPC BeOS.
1471
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001472- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001473 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001474
1475- Cygwin: Support for shared libraries, Tkinter, and sockets.
1476
1477- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1478
1479Tools and other miscellany
1480
1481- Removed debugging prints from main used with freeze.
1482
Tim Peters46446d62000-10-09 21:19:31 +00001483- IDLE auto-indent no longer crashes when it encounters Unicode
1484 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001485
1486What's new in 2.0 beta 2 (since beta 1)?
1487========================================
1488
1489Core language, builtins, and interpreter
1490
Tim Peters482c0212000-09-26 06:33:09 +00001491- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001492 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001493
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001494- Add -h and -V command line options to print the usage message and
1495 Python version number and exit immediately.
1496
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001497- eval() and exec accept Unicode objects as code parameters.
1498
1499- getattr() and setattr() now also accept Unicode objects for the
1500 attribute name, which are converted to strings using the default
1501 encoding before lookup.
1502
1503- Multiplication on string and Unicode now does proper bounds
1504 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1505 string is too long."
1506
1507- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001508 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001509
Jeremy Hylton1b618592000-09-26 05:32:36 +00001510
1511Standard library and extensions
1512
Guido van Rossum5b08f132001-04-16 02:05:23 +00001513- socket module: the OpenSSL code now adds support for RAND_status()
1514 and EGD (Entropy Gathering Device).
1515
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001516- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001517 argument checking; it still takes no arguments.
1518
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001519- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001520
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001521- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001522
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001523- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001524
1525- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001526 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001527
1528- copy: Copy Unicode objects atomically.
1529
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001530- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001531
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001532- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001533
Fred Drake67233bc2000-09-26 16:40:27 +00001534- dbm: Add get() and setdefault() methods to dbm object. Add constant
1535 `library' to module that names the library used. Added doc strings
1536 and method names to error messages. Uses configure to determine
1537 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1538 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001539
1540- distutils: Update to version 0.9.3.
1541
1542- dl: Add several dl.RTLD_ constants.
1543
1544- fpectl: Now supported on FreeBSD.
1545
1546- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1547 found by the collector will be saved in gc.garbage. This is useful
1548 for debugging a program that creates reference cycles.
1549
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001550- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001551 of HTTP class. Do not close socket on zero-length response. Do not
1552 crash when server sends invalid content-length header.
1553
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001554- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001555
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001556- marshal: When reading a short, sign-extend on platforms where shorts
1557 are bigger than 16 bits. When reading a long, repair the unportable
1558 sign extension that was being done for 64-bit machines. (It assumed
1559 that signed right shift sign-extends.)
1560
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001561- operator: Add contains(), invert(), __invert__() as aliases for
1562 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001563
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001564- os: Add support for popen2() and popen3() on all platforms where
1565 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001566
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001567- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001568 clicking on a file in Explorer (or passing the file name to the
1569 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001570
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001571- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001572 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001573
1574- pickle: Now raises ValueError when an invalid pickle that contains
1575 a non-string repr where a string repr was expected. This behavior
1576 matches cPickle.
1577
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001578- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001579
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001580- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001581
1582- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001583 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001584 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001585
1586- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001587 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001588
1589- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001590 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001591 few cycles during startup since the first call to
1592 setdefaultencoding() will initialize the codec registry and the
1593 encodings package.
1594
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001595- socket: Support for size hint in readlines() method of object returned
1596 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001597
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001598- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001599 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001600 is followed by whitespace.
1601
Tim Petersa3a3a032000-11-30 05:22:44 +00001602- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001603
1604- struct: Check ranges for bytes and shorts.
1605
1606- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001607 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001608
1609- Tkinter: Image objects are now guaranteed to have unique ids. Set
1610 event.delta to zero if Tk version doesn't support mousewheel.
1611 Removed some debugging prints.
1612
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001613- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001614
Fred Drake67233bc2000-09-26 16:40:27 +00001615- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001616 which works around a bug in Norton AntiVirus 2000 that leads directly
1617 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001618
1619- xml: New version detection code allows PyXML to override standard
1620 XML package if PyXML version is greater than 0.6.1.
1621
Fred Drake64bb3802000-09-26 16:21:35 +00001622- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1623 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1624 tree only for nodes which are sufficiently interesting to a specific
1625 application. Does not provide the HTML-specific extensions. Still
1626 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001627
Fred Drake64bb3802000-09-26 16:21:35 +00001628- xml.sax: SAX 2 support for Python, including all the handler
1629 interfaces needed to process XML 1.0 compliant XML. Some
1630 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001631
Fred Drake64bb3802000-09-26 16:21:35 +00001632- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1633 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001634
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001635
Jeremy Hylton1b618592000-09-26 05:32:36 +00001636C API
1637
1638- Add three new convenience functions for module initialization --
1639 PyModule_AddObject(), PyModule_AddIntConstant(), and
1640 PyModule_AddStringConstant().
1641
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001642- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001643 removed and add #error to Python.h if NULL isn't defined after
1644 #include of stdio.h.
1645
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001646- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001647 backwards compatibility (at the source level) with old extensions.
1648
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001649- A wrapper API was added for signal() and sigaction(). Instead of
1650 either function, always use PyOS_getsig() to get a signal handler
1651 and PyOS_setsig() to set one. A new convenience typedef
1652 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001653
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001654- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001655 internal data buffer and size of a string object -- or the default
1656 encoded version of a Unicode object.
1657
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001658- PyString_Size() and PyString_AsString() accept Unicode objects.
1659
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001660- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001661 exists). INT_MAX and LONG_MAX will always be defined, even if
1662 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001663
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001664- PyFloat_FromString takes a second argument, pend, that was
1665 effectively useless. It is now officially useless but preserved for
1666 backwards compatibility. If the pend argument is not NULL, *pend is
1667 set to NULL.
1668
1669- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1670 for the attribute name. See note on getattr() above.
1671
1672- A few bug fixes to argument processing for Unicode.
1673 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1674 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1675 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001676 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001677
1678- Py_BuildValue accepts B format (for bgen-generated code).
1679
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001680
Jeremy Hylton1b618592000-09-26 05:32:36 +00001681Internals
1682
1683- On Unix, fix code for finding Python installation directory so that
1684 it works when argv[0] is a relative path.
1685
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001686- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001687 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001688 rather than by generating a copy of the object.
1689
Tim Peters482c0212000-09-26 06:33:09 +00001690- Several of the internal Unicode tables are much smaller now, and
1691 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001692
Jeremy Hylton97693b02000-09-26 17:42:51 +00001693- In the garbage collector: Fixed bug in collection of tuples. Fixed
1694 bug that caused some instances to be removed from the container set
1695 while they were still live. Fixed parsing in gc.set_debug() for
1696 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001697
1698- Fixed refcount problem in instance deallocation that only occurred
1699 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1700
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001701- On Windows, getpythonregpath is now protected against null data in
1702 registry key.
1703
1704- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001705 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001706
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001707
Jeremy Hylton1b618592000-09-26 05:32:36 +00001708Build and platform-specific issues
1709
1710- Better support of GNU Pth via --with-pth configure option.
1711
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001712- Python/C API now properly exposed to dynamically-loaded extension
1713 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001714
1715- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1716 Don't define MS_SYNC to be zero when it is undefined. Added missing
1717 prototypes in posixmodule.c.
1718
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001719- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001720 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001721
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001722- Fix largefile support on older NetBSD systems and OpenBSD by adding
1723 define for TELL64.
1724
1725
1726Tools and other miscellany
1727
1728- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1729
1730- freeze: The modulefinder now works with 2.0 opcodes.
1731
Tim Petersa3a3a032000-11-30 05:22:44 +00001732- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001733 Move hackery of sys.argv until after the Tk instance has been
1734 created, which allows the application-specific Tkinter
1735 initialization to be executed if present; also pass an explicit
1736 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001737
Jeremy Hylton1b618592000-09-26 05:32:36 +00001738
1739What's new in 2.0 beta 1?
1740=========================
1741
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001742Source Incompatibilities
1743------------------------
1744
1745None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1746such as single-argument append(), connect() and bind(), and changes to
1747str(long) and repr(float).
1748
1749
1750Binary Incompatibilities
1751------------------------
1752
1753- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1754with Python 2.0; these extensions will have to be rebuilt for Python
17552.0.
1756
1757- On Windows, attempting to import a third party extension built for
1758Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1759can do about this. Check your PYTHONPATH environment variable!
1760
1761- Python bytecode files (*.pyc and *.pyo) are not compatible between
1762releases.
1763
1764
1765Overview of Changes Since 1.6
1766-----------------------------
1767
1768There are many new modules (including brand new XML support through
1769the xml package, and i18n support through the gettext module); a list
1770of all new modules is included below. Lots of bugs have been fixed.
1771
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001772The process for making major new changes to the language has changed
1773since Python 1.6. Enhancements must now be documented by a Python
1774Enhancement Proposal (PEP) before they can be accepted.
1775
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001776There are several important syntax enhancements, described in more
1777detail below:
1778
1779 - Augmented assignment, e.g. x += 1
1780
1781 - List comprehensions, e.g. [x**2 for x in range(10)]
1782
1783 - Extended import statement, e.g. import Module as Name
1784
1785 - Extended print statement, e.g. print >> file, "Hello"
1786
1787Other important changes:
1788
1789 - Optional collection of cyclical garbage
1790
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001791Python Enhancement Proposal (PEP)
1792---------------------------------
1793
1794PEP stands for Python Enhancement Proposal. A PEP is a design
1795document providing information to the Python community, or describing
1796a new feature for Python. The PEP should provide a concise technical
1797specification of the feature and a rationale for the feature.
1798
1799We intend PEPs to be the primary mechanisms for proposing new
1800features, for collecting community input on an issue, and for
1801documenting the design decisions that have gone into Python. The PEP
1802author is responsible for building consensus within the community and
1803documenting dissenting opinions.
1804
1805The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001806
1807Augmented Assignment
1808--------------------
1809
1810This must have been the most-requested feature of the past years!
1811Eleven new assignment operators were added:
1812
Guido van Rossume905e952000-09-05 12:42:46 +00001813 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001814
1815For example,
1816
1817 A += B
1818
1819is similar to
1820
1821 A = A + B
1822
1823except that A is evaluated only once (relevant when A is something
1824like dict[index].attr).
1825
1826However, if A is a mutable object, A may be modified in place. Thus,
1827if A is a number or a string, A += B has the same effect as A = A+B
1828(except A is only evaluated once); but if a is a list, A += B has the
1829same effect as A.extend(B)!
1830
1831Classes and built-in object types can override the new operators in
1832order to implement the in-place behavior; the not-in-place behavior is
1833used automatically as a fallback when an object doesn't implement the
1834in-place behavior. For classes, the method name is derived from the
1835method name for the corresponding not-in-place operator by inserting
1836an 'i' in front of the name, e.g. __iadd__ implements in-place
1837__add__.
1838
1839Augmented assignment was implemented by Thomas Wouters.
1840
1841
1842List Comprehensions
1843-------------------
1844
1845This is a flexible new notation for lists whose elements are computed
1846from another list (or lists). The simplest form is:
1847
1848 [<expression> for <variable> in <sequence>]
1849
Guido van Rossum56db0952000-09-06 23:34:25 +00001850For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001851This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001852
1853You can also add a condition:
1854
1855 [<expression> for <variable> in <sequence> if <condition>]
1856
1857For example, [w for w in words if w == w.lower()] would yield the list
1858of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001859than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001860
1861You can also have nested for loops and more than one 'if' clause. For
1862example, here's a function that flattens a sequence of sequences::
1863
1864 def flatten(seq):
1865 return [x for subseq in seq for x in subseq]
1866
1867 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1868
1869This prints
1870
1871 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1872
1873List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001874Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001875
1876
1877Extended Import Statement
1878-------------------------
1879
1880Many people have asked for a way to import a module under a different
1881name. This can be accomplished like this:
1882
1883 import foo
1884 bar = foo
1885 del foo
1886
1887but this common idiom gets old quickly. A simple extension of the
1888import statement now allows this to be written as follows:
1889
1890 import foo as bar
1891
1892There's also a variant for 'from ... import':
1893
1894 from foo import bar as spam
1895
1896This also works with packages; e.g. you can write this:
1897
1898 import test.regrtest as regrtest
1899
1900Note that 'as' is not a new keyword -- it is recognized only in this
1901context (this is only possible because the syntax for the import
1902statement doesn't involve expressions).
1903
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001904Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001905
1906
1907Extended Print Statement
1908------------------------
1909
1910Easily the most controversial new feature, this extension to the print
1911statement adds an option to make the output go to a different file
1912than the default sys.stdout.
1913
1914For example, to write an error message to sys.stderr, you can now
1915write:
1916
1917 print >> sys.stderr, "Error: bad dog!"
1918
1919As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001920evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001921
1922 print >> None, "Hello world"
1923
1924is equivalent to
1925
1926 print "Hello world"
1927
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001928Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001929
1930
1931Optional Collection of Cyclical Garbage
1932---------------------------------------
1933
1934Python is now equipped with a garbage collector that can hunt down
1935cyclical references between Python objects. It's no replacement for
1936reference counting; in fact, it depends on the reference counts being
1937correct, and decides that a set of objects belong to a cycle if all
1938their reference counts can be accounted for from their references to
1939each other. This devious scheme was first proposed by Eric Tiedemann,
1940and brought to implementation by Neil Schemenauer.
1941
1942There's a module "gc" that lets you control some parameters of the
1943garbage collection. There's also an option to the configure script
1944that lets you enable or disable the garbage collection. In 2.0b1,
1945it's on by default, so that we (hopefully) can collect decent user
1946experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001947performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001948off by default in the final 2.0 release.
1949
1950
1951Smaller Changes
1952---------------
1953
1954A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1955map(None, seq1, seq2, ...) when the sequences have the same length;
1956i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1957the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001958zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001959
1960sys.version_info is a tuple (major, minor, micro, level, serial).
1961
1962Dictionaries have an odd new method, setdefault(key, default).
1963dict.setdefault(key, default) returns dict[key] if it exists; if not,
1964it sets dict[key] to default and returns that value. Thus:
1965
1966 dict.setdefault(key, []).append(item)
1967
1968does the same work as this common idiom:
1969
1970 if not dict.has_key(key):
1971 dict[key] = []
1972 dict[key].append(item)
1973
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001974There are two new variants of SyntaxError that are raised for
1975indentation-related errors: IndentationError and TabError.
1976
1977Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1978escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001979
1980The limits on the size of expressions and file in Python source code
1981have been raised from 2**16 to 2**32. Previous versions of Python
1982were limited because the maximum argument size the Python VM accepted
1983was 2**16. This limited the size of object constructor expressions,
1984e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1985limit was raised thanks to a patch by Charles Waldman that effectively
1986fixes the problem. It is now much more likely that you will be
1987limited by available memory than by an arbitrary limit in Python.
1988
1989The interpreter's maximum recursion depth can be modified by Python
1990programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1991limit is the maximum number of recursive calls that can be made by
1992Python code. The limit exists to prevent infinite recursion from
1993overflowing the C stack and causing a core dump. The default value is
19941000. The maximum safe value for a particular platform can be found
1995by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001996
1997New Modules and Packages
1998------------------------
1999
2000atexit - for registering functions to be called when Python exits.
2001
2002imputil - Greg Stein's alternative API for writing custom import
2003hooks.
2004
2005pyexpat - an interface to the Expat XML parser, contributed by Paul
2006Prescod.
2007
2008xml - a new package with XML support code organized (so far) in three
2009subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
2010would fill a volume. There's a special feature whereby a
2011user-installed package named _xmlplus overrides the standard
2012xmlpackage; this is intended to give the XML SIG a hook to distribute
2013backwards-compatible updates to the standard xml package.
2014
2015webbrowser - a platform-independent API to launch a web browser.
2016
2017
Guido van Rossume905e952000-09-05 12:42:46 +00002018Changed Modules
2019---------------
2020
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002021array -- new methods for array objects: count, extend, index, pop, and
2022remove
2023
2024binascii -- new functions b2a_hex and a2b_hex that convert between
2025binary data and its hex representation
2026
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002027calendar -- Many new functions that support features including control
2028over which day of the week is the first day, returning strings instead
2029of printing them. Also new symbolic constants for days of week,
2030e.g. MONDAY, ..., SUNDAY.
2031
2032cgi -- FieldStorage objects have a getvalue method that works like a
2033dictionary's get method and returns the value attribute of the object.
2034
2035ConfigParser -- The parser object has new methods has_option,
2036remove_section, remove_option, set, and write. They allow the module
2037to be used for writing config files as well as reading them.
2038
2039ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002040optionally support the RFC 959 REST command.
2041
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002042gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002043
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002044httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2045the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002046
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002047locale -- implement getdefaultlocale for Win32 and Macintosh
2048
2049marshal -- no longer dumps core when marshaling deeply nested or
2050recursive data structures
2051
2052os -- new functions isatty, seteuid, setegid, setreuid, setregid
2053
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002054os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2055support under Unix.
2056
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002057os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002058
2059os.path -- fix semantics of os.path.commonprefix
2060
2061smtplib -- support for sending very long messages
2062
2063socket -- new function getfqdn()
2064
2065readline -- new functions to read, write and truncate history files.
2066The readline section of the library reference manual contains an
2067example.
2068
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002069select -- add interface to poll system call
2070
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002071shutil -- new copyfileobj function
2072
2073SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2074HTTP server.
2075
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002076Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002077
2078urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002079e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002080
2081whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002082
2083
2084Obsolete Modules
2085----------------
2086
2087None. However note that 1.6 made a whole slew of modules obsolete:
2088stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2089poly, zmod, strop, util, whatsound.
2090
2091
2092Changed, New, Obsolete Tools
2093----------------------------
2094
Tim Peters8b092332000-09-05 20:15:25 +00002095None.
Guido van Rossume905e952000-09-05 12:42:46 +00002096
2097
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002098C-level Changes
2099---------------
2100
2101Several cleanup jobs were carried out throughout the source code.
2102
2103All C code was converted to ANSI C; we got rid of all uses of the
2104Py_PROTO() macro, which makes the header files a lot more readable.
2105
2106Most of the portability hacks were moved to a new header file,
2107pyport.h; several other new header files were added and some old
2108header files were removed, in an attempt to create a more rational set
2109of header files. (Few of these ever need to be included explicitly;
2110they are all included by Python.h.)
2111
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002112Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002113and Win64, especially for the new Intel Itanium processor. Mick also
2114added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002115
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002116The C APIs to return an object's size have been update to consistently
2117use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2118previous versions, the abstract interfaces used PyXXX_Length and the
2119concrete interfaces used PyXXX_Size. The old names,
2120e.g. PyObject_Length, are still available for backwards compatibility
2121at the API level, but are deprecated.
2122
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002123The PyOS_CheckStack function has been implemented on Windows by
2124Fredrik Lundh. It prevents Python from failing with a stack overflow
2125on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002126
2127The GC changes resulted in creation of two new slots on object,
2128tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002129the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002130
2131The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002132C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002133
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002134PyErr_Format has been updated to automatically calculate the size of
2135the buffer needed to hold the formatted result string. This change
2136prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002137
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002138New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002139
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002140PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2141that are the same as their non-Ex counterparts except they take an
2142extra flag argument that tells them to close the file when done.
2143
2144XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002145
Tim Peters8b092332000-09-05 20:15:25 +00002146
2147Windows Changes
2148---------------
2149
2150New popen2/popen3/peopen4 in os module (see Changed Modules above).
2151
2152os.popen is much more usable on Windows 95 and 98. See Microsoft
2153Knowledge Base article Q150956. The Win9x workaround described there
2154is implemented by the new w9xpopen.exe helper in the root of your
2155Python installation. Note that Python uses this internally; it is not
2156a standalone program.
2157
2158Administrator privileges are no longer required to install Python
2159on Windows NT or Windows 2000. If you have administrator privileges,
2160Python's registry info will be written under HKEY_LOCAL_MACHINE.
2161Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002162under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002163uses of Python, but will prevent some advanced uses from working
2164(for example, running a Python script as an NT service, or possibly
2165from CGI).
2166
2167[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2168installer; instead, it installs the needed Tcl/Tk files directly in the
2169Python directory. If you already have a Tcl/Tk installation, this
2170wastes some disk space (about 4 Megs) but avoids problems with
2171conflicting Tcl/Tk installations, and makes it much easier for Python
2172to ensure that Tcl/Tk can find all its files.
2173
2174[This was new in 1.6] The Windows installer now installs by default in
2175\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2176
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002177
2178Updates to the changes between 1.5.2 and 1.6
2179--------------------------------------------
2180
2181The 1.6 NEWS file can't be changed after the release is done, so here
2182is some late-breaking news:
2183
2184New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2185and changes to getlocale() and setlocale().
2186
2187The new module is now enabled per default.
2188
2189It is not true that the encodings codecs cannot be used for normal
2190strings: the string.encode() (which is also present on 8-bit strings
2191!) allows using them for 8-bit strings too, e.g. to convert files from
2192cp1252 (Windows) to latin-1 or vice-versa.
2193
2194Japanese codecs are available from Tamito KAJIYAMA:
2195http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2196
2197
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002198======================================================================