blob: 6cb27f0f8a538890a7731763bad230a1715ee163 [file] [log] [blame]
Tim Petersedc99312001-08-22 21:36:50 +00001What's New in Python 2.2a3?
2===========================
3
4Core
5
6Library
7
8Tools
9
10Build
11
12New platforms
13
14Tests
15
16Windows
17
Tim Peters402d5982001-08-27 06:37:48 +000018+ The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
19 points to command.com (patch from Brian Quinlan).
20
Tim Petersedc99312001-08-22 21:36:50 +000021
Tim Peters20f51a72001-07-21 02:31:40 +000022What's New in Python 2.2a2?
23===========================
24
Martin v. Löwis339d0f72001-08-17 18:39:25 +000025Build
26
Barry Warsaw18b2ecf2001-08-22 20:26:56 +000027- Tim Peters developed a brand new Windows installer using Wise 8.1,
28 generously donated to us by Wise Solutions.
29
Martin v. Löwis339d0f72001-08-17 18:39:25 +000030- configure supports a new option --enable-unicode, with the values
31 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
32 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +000033
Jack Jansen32ce0cd2001-08-21 19:28:20 +000034- A new configure option --enable-framework builds a Mac OS X framework,
35 which "make frameworkinstall" will install. This provides a starting
36 point for more mac-like functionality, join pythonmac-sig@python.org
37 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +000038
Barry Warsaw6f3410d2001-08-22 04:08:41 +000039- The NeXT platform is no longer supported.
40
41- The `new' module is now statically linked.
42
Tim Peters0afb6092001-08-15 06:06:44 +000043Tools
44
45- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +000046 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +000047 the module docstring for details.
48
Tim Peters20f51a72001-07-21 02:31:40 +000049Tests
50
Tim Peters5e824c32001-08-12 22:25:01 +000051- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +000052 platforms, allowing to give clearer test result output. regrtest
53 also has optional --use/-u switch to run normally disabled tests
54 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +000055
Tim Peters20f51a72001-07-21 02:31:40 +000056- Several new tests in the standard test suite, with special thanks to
57 Nick Mathewson.
58
59Core
60
Barry Warsaw6f3410d2001-08-22 04:08:41 +000061- The floor division operator // has been added as outlined in PEP
62 238. The / operator still provides classic division (and will until
63 Python 3.0) unless "from __future__ import division" is included, in
64 which case the / operator will provide true division. The operator
65 module provides truediv() and floordiv() functions. Augmented
66 assignment variants are included, as are the equivalent overloadable
67 methods and C API methods. See the PEP for a full discussion:
68 <http://python.sf.net/peps/pep-0238.html>
69
Tim Peters6cd6a822001-08-17 22:11:27 +000070- Future statements are now effective in simulated interactive shells
71 (like IDLE). This should "just work" by magic, but read Michael
72 Hudson's "Future statements in simulated shells" PEP 264 for full
73 details: <http://python.sf.net/peps/pep-0264.html>.
74
Guido van Rossumf86ddd22001-08-17 21:21:04 +000075- The type/class unification (PEP 252-253) was integrated into the
76 trunk and is not so tentative any more (the exact specification of
77 some features is still tentative). A lot of work has done on fixing
78 bugs and adding robustness and features (performance still has to
79 come a long way).
80
Marc-André Lemburg888fac02001-07-31 14:24:31 +000081- Warnings about a mismatch in the Python API during extension import
82 now use the Python warning framework (which makes it possible to
83 write filters for these warnings).
84
Barry Warsaw9b3be7f2001-08-14 18:35:02 +000085- A function's __dict__ (aka func_dict) will now always be a
86 dictionary. It used to be possible to delete it or set it to None,
87 but now both actions raise TypeErrors. It is still legal to set it
88 to a dictionary object. Getting func.__dict__ before any attributes
89 have been assigned now returns an empty dictionary instead of None.
90
Marc-André Lemburgd6277912001-07-31 14:42:42 +000091Library
92
Tim Peters5e824c32001-08-12 22:25:01 +000093- New class Differ and new functions ndiff() and restore() in difflib.py.
94 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +000095 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +000096
Marc-André Lemburgd6277912001-07-31 14:42:42 +000097- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
98 value using the minimal quoting required for the value; more
99 reliable than using xml.sax.saxutils.escape() for attribute values.
100
101- Readline completion support for cmd.Cmd was added.
102
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000103- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
104
105- Added function threading.BoundedSemaphore()
106
107- Added Ka-Ping Yee's cgitb.py module.
108
109- The `new' module now exposes the CO_xxx flags.
110
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000111New platforms
112
113C API
114
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000115- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
116 which provide a cross-platform implementations for the
117 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
118 the standard sprintf() and vsprintf() C lib APIs, these versions
119 apply bounds checking on the used buffer which enhances protection
120 against buffer overruns.
121
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000122- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000123 and extensions using different Unicode widths is rendered next to
124 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000125 will result in an ImportError. Unicode extensions writers must make
126 sure to check the Unicode width compatibility in their extensions by
127 using at least one of the mangled Unicode APIs in the extension.
128
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000129- Two new flags METH_NOARGS and METH_O are available in method definition
130 tables to simplify implementation of methods with no arguments and a
131 single untyped argument. Calling such methods is more efficient than
132 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
133 deprecated.
134
Tim Petersc1731372001-08-04 08:12:36 +0000135Windows
136
137- "import module" now compiles module.pyw if it exists and nothing else
138 relevant is found.
139
Tim Peters20f51a72001-07-21 02:31:40 +0000140
Guido van Rossum55a78992001-07-17 17:22:32 +0000141What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000142===========================
143
144Core
Tim Petersa814db52001-05-14 07:05:58 +0000145
Tim Peters6d6c1a32001-08-02 04:15:00 +0000146- TENTATIVELY, a large amount of code implementing much of what's
147 described in PEP 252 (Making Types Look More Like Classes) and PEP
148 253 (Subtyping Built-in Types) was added. This will be released
149 with Python 2.2a1. Documentation will be provided separately
150 through http://www.python.org/2.2/. The purpose of releasing this
151 with Python 2.2a1 is to test backwards compatibility. It is
152 possible, though not likely, that a decision is made not to release
153 this code as part of 2.2 final, if any serious backwards
154 incompapatibilities are found during alpha testing that cannot be
155 repaired.
156
Guido van Rossum55a78992001-07-17 17:22:32 +0000157- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000158 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000159 more 'yield' statements. See PEP 255. Since this adds a new
160 keyword to the language, this feature must be enabled by including a
161 future statement: "from __future__ import generators" (see PEP 236).
162 Generators will become a standard feature in a future release
163 (probably 2.3). Without this future statement, 'yield' remains an
164 ordinary identifier, but a warning is issued each time it is used.
165 (These warnings currently don't conform to the warnings framework of
166 PEP 230; we intend to fix this in 2.2a2.)
167
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000168- The UTF-16 codec was modified to be more RFC compliant. It will now
169 only remove BOM characters at the start of the string and then
170 only if running in native mode (UTF-16-LE and -BE won't remove a
171 leading BMO character).
172
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000173- Strings now have a new method .decode() to complement the already
174 existing .encode() method. These two methods provide direct access
175 to the corresponding decoders and encoders of the registered codecs.
176
177 To enhance the usability of the .encode() method, the special
178 casing of Unicode object return values was dropped (Unicode objects
179 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000180
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000181 Both methods will now return whatever the codec in charge of the
182 requested encoding returns as object, e.g. Unicode codecs will
183 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
184 will return u"äöü"). This enables codec writer to create codecs
185 for various simple to use conversions.
186
187 New codecs were added to demonstrate these new features (the .encode()
188 and .decode() columns indicate the type of the returned objects):
189
190 Name | .encode() | .decode() | Description
191 ----------------------------------------------------------------------
192 uu | string | string | UU codec (e.g. for email)
193 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000194 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000195 zlib | string | string | zlib compression
196 hex | string | string | 2-byte hex codec
197 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
198
Mark Hammond2a0af792001-05-14 03:09:36 +0000199- Some operating systems now support the concept of a default Unicode
200 encoding for file system operations. Notably, Windows supports 'mbcs'
201 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000202 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000203 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000204
205 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000206 functions that return filenames (such as os.listdir()) to return Python
207 string objects pre-encoded using the default file system encoding for
208 the platform. As this encoding is likely to be different from Python's
209 default encoding, converting this name to a Unicode object before passing
210 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000211 would attempt to use its default encoding (generally ASCII) rather than
212 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000213
Tim Petersa814db52001-05-14 07:05:58 +0000214 In general, this change simply removes surprises when working with
215 Unicode and the file system, making these operations work as you expect,
216 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000217 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000218
Tim Peters61dff2b2001-05-08 15:43:37 +0000219- Float (and complex) literals in source code were evaluated to full
220 precision only when running from a .py file; the same code loaded from a
221 .pyc (or .pyo) file could suffer numeric differences starting at about the
222 12th significant decimal digit. For example, on a machine with IEEE-754
223 floating arithmetic,
224
225 x = 9007199254740992.0
226 print long(x)
227
228 printed 9007199254740992 if run directly from .py, but 9007199254740000
229 if from a compiled (.pyc or .pyo) file. This was due to marshal using
230 str(float) instead of repr(float) when building code objects. marshal
231 now uses repr(float) instead, which should reproduce floats to full
232 machine precision (assuming the platform C float<->string I/O conversion
233 functions are of good quality).
234
235 This may cause floating-point results to change in some cases, and
236 usually for the better, but may also cause numerically unstable
237 algorithms to break.
238
Tim Peters2f228e72001-05-13 00:19:31 +0000239- The implementation of dicts suffers fewer collisions, which has speed
240 benefits. However, the order in which dict entries appear in dict.keys(),
241 dict.values() and dict.items() may differ from previous releases for a
242 given dict. Nothing is defined about this order, so no program should
243 rely on it. Nevertheless, it's easy to write test cases that rely on the
244 order by accident, typically because of printing the str() or repr() of a
245 dict to an "expected results" file. See Lib/test/test_support.py's new
246 sortdict(dict) function for a simple way to display a dict in sorted
247 order.
248
Tim Peters7a3bfc32001-06-12 01:22:22 +0000249- Many other small changes to dicts were made, resulting in faster
250 operation along the most common code paths.
251
Guido van Rossum10315822001-05-01 20:54:30 +0000252- Dictionary objects now support the "in" operator: "x in dict" means
253 the same as dict.has_key(x).
254
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000255- The update() method of dictionaries now accepts generic mapping
256 objects. Specifically the argument object must support the .keys()
257 and __getitem__() methods. This allows you to say, for example,
258 {}.update(UserDict())
259
Guido van Rossum10315822001-05-01 20:54:30 +0000260- Iterators were added; this is a generalized way of providing values
261 to a for loop. See PEP 234. There's a new built-in function iter()
262 to return an iterator. There's a new protocol to get the next value
263 from an iterator using the next() method (in Python) or the
264 tp_iternext slot (in C). There's a new protocol to get iterators
265 using the __iter__() method (in Python) or the tp_iter slot (in C).
266 Iterating (i.e. a for loop) over a dictionary generates its keys.
267 Iterating over a file generates its lines.
268
Tim Petersf553f892001-05-01 20:45:31 +0000269- The following functions were generalized to work nicely with iterator
270 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000271 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000272 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
273 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000274 join() method of strings
275 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000276 'x in y' and 'x not in y' (PySequence_Contains() in C API)
277 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000278 right-hand side of assignment statements with multiple targets, such as
279 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000280
Tim Petersd85e1022001-05-11 21:51:48 +0000281- Accessing module attributes is significantly faster (for example,
282 random.random or os.path or yourPythonModule.yourAttribute).
283
Tim Peterse63415e2001-05-08 04:38:29 +0000284- Comparing dictionary objects via == and != is faster, and now works even
285 if the keys and values don't support comparisons other than ==.
286
Tim Peters95bf9392001-05-10 08:32:44 +0000287- Comparing dictionaries in ways other than == and != is slower: there were
288 insecurities in the dict comparison implementation that could cause Python
289 to crash if the element comparison routines for the dict keys and/or
290 values mutated the dicts. Making the code bulletproof slowed it down.
291
Tim Peterseb28ef22001-06-02 05:27:19 +0000292- Collisions in dicts are resolved via a new approach, which can help
293 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000294 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000295 faster now. Thanks to Christian Tismer for pointing out the cause and
296 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000297
Tim Peters52e155e2001-06-16 05:42:57 +0000298- repr() is much faster for large containers (dict, list, tuple).
299
300
Tim Petersa814db52001-05-14 07:05:58 +0000301Library
302
Fred Drake960fdf92001-07-20 18:38:26 +0000303- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
304 were added to the string module. These a locale-indenpendent
305 constants, unlike letters, lowercase, and uppercase. These are now
306 use in appropriate locations in the standard library.
307
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000308- The flags used in dlopen calls can now be configured using
309 sys.setdlopenflags and queried using sys.getdlopenflags.
310
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000311- Fredrik Lundh's xmlrpclib is now a standard library module. This
312 provides full client-side XML-RPC support. In addition,
313 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
314 one asyncore-based). Thanks to Eric Raymond for the documentation.
315
Guido van Rossum643d3912001-07-05 14:46:25 +0000316- The xrange() object is simplified: it no longer supports slicing,
317 repetition, comparisons, efficient 'in' checking, the tolist()
318 method, or the start, stop and step attributes. See PEP 260.
319
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000320- A new function fnmatch.filter to filter lists of file names was added.
321
Barry Warsawffd674d2001-05-22 16:00:10 +0000322- calendar.py uses month and day names based on the current locale.
323
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000324- strop is now *really* obsolete (this was announced before with 1.6),
325 and issues DeprecationWarning when used (except for the four items
326 that are still imported into string.py).
327
Tim Petersa814db52001-05-14 07:05:58 +0000328- Cookie.py now sorts key+value pairs by key in output strings.
329
330- pprint.isrecursive(object) didn't correctly identify recursive objects.
331 Now it does.
332
Tim Peters95b3f782001-05-14 18:39:41 +0000333- pprint functions now much faster for large containers (tuple, list, dict).
334
Tim Peters7b9542a2001-06-10 23:40:19 +0000335- New 'q' and 'Q' format codes in the struct module, corresponding to C
336 types "long long" and "unsigned long long" (on Windows, __int64). In
337 native mode, these can be used only when the platform C compiler supports
338 these types (when HAVE_LONG_LONG is #define'd by the Python config
339 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000340 In standard mode, 'q' and 'Q' are supported on all platforms, and are
341 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000342
Guido van Rossum83213cc2001-06-12 16:48:52 +0000343- The site module installs a new built-in function 'help' that invokes
344 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
345 it displays a message reminding the user to use 'help()' or
346 'help(object)'.
347
Tim Petersa814db52001-05-14 07:05:58 +0000348Tests
349
350- New test_mutants.py runs dict comparisons where the key and value
351 comparison operators mutute the dicts randomly during comparison. This
352 rapidly causes Python to crash under earlier releases (not for the faint
353 of heart: it can also cause Win9x to freeze or reboot!).
354
355- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000356 pprint.isreadable() return sensible results. Also verifies that simple
357 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000358
Tim Peters58e0a8c2001-05-14 22:32:33 +0000359New platforms
360
361- Python should compile and run out of the box using the Borland C
362 compiler (under Windows), thanks to Stephen Hansen.
Tim Petersf553f892001-05-01 20:45:31 +0000363
Tim Peters4324aa32001-05-28 22:30:08 +0000364C API
365
366- Removed the unused last_is_sticky argument from the internal
367 _PyTuple_Resize(). If this affects you, you were cheating.
368
369
Guido van Rossum55a78992001-07-17 17:22:32 +0000370======================================================================
371
372
Guido van Rossumffe13be2001-04-16 18:46:45 +0000373What's New in Python 2.1 (final)?
374=================================
375
376We only changed a few things since the last release candidate, all in
377Python library code:
378
379- A bug in the locale module was fixed that affected locales which
380 define no grouping for numeric formatting.
381
382- A few bugs in the weakref module's implementations of weak
383 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
384 and the test suite was updated to check for these bugs.
385
386- An old bug in the os.path.walk() function (introduced in Python
387 2.0!) was fixed: a non-existent file would cause an exception
388 instead of being ignored.
389
390- Fixed a few bugs in the new symtable module found by Neil Norwitz's
391 PyChecker.
392
393
Guido van Rossum5b08f132001-04-16 02:05:23 +0000394What's New in Python 2.1c2?
395===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000396
Guido van Rossum5b08f132001-04-16 02:05:23 +0000397A flurry of small changes, and one showstopper fixed in the nick of
398time made it necessary to release another release candidate. The list
399here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000400
Guido van Rossum5b08f132001-04-16 02:05:23 +0000401Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000402
Guido van Rossum5b08f132001-04-16 02:05:23 +0000403- Tim discovered a nasty bug in the dictionary code, caused by
404 PyDict_Next() calling dict_resize(), and the GC code's use of
405 PyDict_Next() violating an assumption in dict_items(). This was
406 fixed with considerable amounts of band-aid, but the net effect is a
407 saner and more robust implementation.
408
409- Made a bunch of symbols static that were accidentally global.
410
411Build and Ports
412
413- The setup.py script didn't check for a new enough version of zlib
414 (1.1.3 is needed). Now it does.
415
416- Changed "make clean" target to also remove shared libraries.
417
418- Added a more general warning about the SGI Irix optimizer to README.
419
420Library
421
422- Fix a bug in urllib.basejoin("http://host", "../file.html") which
423 omitted the slash between host and file.html.
424
425- The mailbox module's _Mailbox class contained a completely broken
426 and undocumented seek() method. Ripped it out.
427
428- Fixed a bunch of typos in various library modules (urllib2, smtpd,
429 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
430
431- Fixed a few last-minute bugs in unittest.
432
433Extensions
434
435- Reverted the patch to the OpenSSL code in socketmodule.c to support
436 RAND_status() and the EGD, and the subsequent patch that tried to
437 fix it for pre-0.9.5 versions; the problem with the patch is that on
438 some systems it issues a warning whenever socket is imported, and
439 that's unacceptable.
440
441Tests
442
443- Fixed the pickle tests to work with "import test.test_pickle".
444
445- Tweaked test_locale.py to actually run the test Windows.
446
447- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
448 not "wb" (which is not a valid mode at all).
449
450- Fix pstats browser crashes. Import readline if it exists to make
451 the user interface nicer.
452
453- Add "import thread" to the top of test modules that import the
454 threading module (test_asynchat and test_threadedtempfile). This
455 prevents test failures caused by a broken threading module resulting
456 from a previously caught failed import.
457
458- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
459 needed on some platforms (e.g. Solaris 8) when the tests are run
460 twice in succession.
461
462- Skip rather than fail test_sunaudiodev if no audio device is found.
463
464
465What's New in Python 2.1c1?
466===========================
467
468This list was significantly updated when 2.1c2 was released; the 2.1c1
469release didn't mention most changes that were actually part of 2.1c1:
470
471Legal
472
473- Copyright was assigned to the Python Software Foundation (PSF) and a
474 PSF license (very similar to the CNRI license) was added.
475
476- The CNRI copyright notice was updated to include 2001.
477
478Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000479
Guido van Rossumc9932722001-04-12 02:31:27 +0000480- After a public outcry, assignment to __debug__ is no longer illegal;
481 instead, a warning is issued. It will become illegal in 2.2.
482
Guido van Rossum5b08f132001-04-16 02:05:23 +0000483- Fixed a core dump with "%#x" % 0, and changed the semantics so that
484 "%#x" now always prepends "0x", even if the value is zero.
485
486- Fixed some nits in the bytecode compiler.
487
488- Fixed core dumps when calling certain kinds of non-functions.
489
490- Fixed various core dumps caused by reference count bugs.
491
492Build and Ports
493
494- Use INSTALL_SCRIPT to install script files.
495
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000496- New port: SCO Unixware 7, by Billy G. Allie.
497
Guido van Rossum5b08f132001-04-16 02:05:23 +0000498- Updated RISCOS port.
499
500- Updated BeOS port and notes.
501
502- Various other porting problems resolved.
503
504Library
505
506- The TERMIOS and SOCKET modules are now truly obsolete and
507 unnecessary. Their symbols are incorporated in the termios and
508 socket modules.
509
510- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
511 better tests for pickling.
512
513- threading: make Condition.wait() robust against KeyboardInterrupt.
514
515- zipfile: add support to zipfile to support opening an archive
516 represented by an open file rather than a file name. Fix bug where
517 the archive was not properly closed. Fixed a bug in this bugfix
518 where flush() was called for a read-only file.
519
520- imputil: added an uninstall() method to the ImportManager.
521
522- Canvas: fixed bugs in lower() and tkraise() methods.
523
524- SocketServer: API change (added overridable close_request() method)
525 so that the TCP server can explicitly close the request.
526
527- pstats: Eric Raymond added a simple interactive statistics browser,
528 invoked when the module is run as a script.
529
530- locale: fixed a problem in format().
531
532- webbrowser: made it work when the BROWSER environment variable has a
533 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
534 KDE 2. Fixed some other nits.
535
536- unittest: changes to allow using a different exception than
537 AssertionError, and added a few more function aliases. Some other
538 small changes.
539
540- urllib, urllib2: fixed redirect problems and a coupleof other nits.
541
542- asynchat: fixed a critical bug in asynchat that slipped through the
543 2.1b2 release. Fixed another rare bug.
544
545- Fix some unqualified except: clauses (always a bad code example).
546
547XML
548
549- pyexpat: new API get_version_string().
550
551- Fixed some minidom bugs.
552
553Extensions
554
555- Fixed a core dump in _weakref. Removed the weakref.mapping()
556 function (it adds nothing to the API).
557
558- Rationalized the use of header files in the readline module, to make
559 it compile (albeit with some warnings) with the very recent readline
560 4.2, without breaking for earlier versions.
561
562- Hopefully fixed a buffering problem in linuxaudiodev.
563
564- Attempted a fix to make the OpenSSL support in the socket module
565 work again with pre-0.9.5 versions of OpenSSL.
566
567Tests
568
569- Added a test case for asynchat and asyncore.
570
571- Removed coupling between tests where one test failing could break
572 another.
573
574Tools
575
576- Ping added an interactive help browser to pydoc, fixed some nits
577 in the rest of the pydoc code, and added some features to his
578 inspect module.
579
580- An updated python-mode.el version 4.1 which integrates Ken
581 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
582 much nicer in XEmacs and Emacs. When stepping through your program
583 with pdb, in either the shell window or the *Python* window, the
584 source file and line will be tracked by an arrow. Very cool!
585
586- IDLE: syntax warnings in interactive mode are changed into errors.
587
588- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +0000589 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +0000590
591- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000592
Barry Warsaw11e89c72001-04-11 20:37:57 +0000593
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000594What's New in Python 2.1 beta 2?
595================================
596
Guido van Rossum053ae352001-03-22 14:17:21 +0000597(Unlisted are many fixed bugs, more documentation, etc.)
598
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000599Core language, builtins, and interpreter
600
Guido van Rossum053ae352001-03-22 14:17:21 +0000601- The nested scopes work (enabled by "from __future__ import
602 nested_scopes") is completed; in particular, the future now extends
603 into code executed through exec, eval() and execfile(), and into the
604 interactive interpreter.
605
606- When calling a base class method (e.g. BaseClass.__init__(self)),
607 this is now allowed even if self is not strictly spoken a class
608 instance (e.g. when using metaclasses or the Don Beaudry hook).
609
610- Slice objects are now comparable but not hashable; this prevents
611 dict[:] from being accepted but meaningless.
612
613- Complex division is now calculated using less braindead algorithms.
614 This doesn't change semantics except it's more likely to give useful
615 results in extreme cases. Complex repr() now uses full precision
616 like float repr().
617
618- sgmllib.py now calls handle_decl() for simple <!...> declarations.
619
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000620- It is illegal to assign to the name __debug__, which is set when the
621 interpreter starts. It is effectively a compile-time constant.
622
623- A warning will be issued if a global statement for a variable
624 follows a use or assignment of that variable.
625
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000626Standard library
627
Guido van Rossum053ae352001-03-22 14:17:21 +0000628- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
629 inspired by JUnit), is now part of the standard library. You now
630 have a choice of two testing frameworks: unittest requires you to
631 write testcases as separate code, doctest gathers them from
632 docstrings. Both approaches have their advantages and
633 disadvantages.
634
635- A new module Tix was added, which wraps the Tix extension library
636 for Tk. With that module, it is not necessary to statically link
637 Tix with _tkinter, since Tix will be loaded with Tcl's "package
638 require" command. See Demo/tix/.
639
640- tzparse.py is now obsolete.
641
642- In gzip.py, the seek() and tell() methods are removed -- they were
643 non-functional anyway, and it's better if callers can test for their
644 existence with hasattr().
645
646Python/C API
647
648- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
649 that's already in the dictionary during a PyDict_Next() iteration.
650 This used to fail occasionally when a dictionary resize operation
651 could be triggered that would rehash all the keys. All other
652 modifications to the dictionary are still off-limits during a
653 PyDict_Next() iteration!
654
655- New extended APIs related to passing compiler variables around.
656
657- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
658 implement isinstance() and issubclass().
659
660- Py_BuildValue() now has a "D" conversion to create a Python complex
661 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000662
Fred Drake4e262a92001-03-22 18:26:47 +0000663- Extensions types which support weak references must now set the
664 field allocated for the weak reference machinery to NULL themselves;
665 this is done to avoid the cost of checking each object for having a
666 weakly referencable type in PyObject_INIT(), since most types are
667 not weakly referencable.
668
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000669- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
670 free variables and cell variables to and from the frame's f_locals.
671
672- Variants of several functions defined in pythonrun.h have been added
673 to support the nested_scopes future statement. The variants all end
674 in Flags and take an extra argument, a PyCompilerFlags *; examples:
675 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
676 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +0000677 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000678
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000679Distutils
680
681- the sdist command now writes a PKG-INFO file, as described in PEP 241,
682 into the release tree.
683
Tim Peters0e57abf2001-05-02 07:39:38 +0000684- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000685 (an uninstaller, more customization of the installer's display)
686
687- from Jack Jansen: added Mac-specific code to generate a dialog for
688 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +0000689 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000690 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +0000691
692- added 'platforms' and 'keywords' to the set of metadata that can be
693 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000694
695- applied patches from Jason Tishler to make the compiler class work with
696 Cygwin.
697
698
Tim Peters2fe289a2001-03-01 22:19:38 +0000699What's New in Python 2.1 beta 1?
700================================
Tim Petersd66595f2001-02-04 03:09:53 +0000701
702Core language, builtins, and interpreter
703
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000704- Following an outcry from the community about the amount of code
705 broken by the nested scopes feature introduced in 2.1a2, we decided
706 to make this feature optional, and to wait until Python 2.2 (or at
707 least 6 months) to make it standard. The option can be enabled on a
708 per-module basis by adding "from __future__ import nested_scopes" at
709 the beginning of a module (before any other statements, but after
710 comments and an optional docstring). See PEP 236 (Back to the
711 __future__) for a description of the __future__ statement. PEP 227
712 (Statically Nested Scopes) has been updated to reflect this change,
713 and to clarify the semantics in a number of endcases.
714
715- The nested scopes code, when enabled, has been hardened, and most
716 bugs and memory leaks in it have been fixed.
717
718- Compile-time warnings are now generated for a number of conditions
719 that will break or change in meaning when nested scopes are enabled:
720
721 - Using "from...import *" or "exec" without in-clause in a function
722 scope that also defines a lambda or nested function with one or
723 more free (non-local) variables. The presence of the import* or
724 bare exec makes it impossible for the compiler to determine the
725 exact set of local variables in the outer scope, which makes it
726 impossible to determine the bindings for free variables in the
727 inner scope. To avoid the warning about import *, change it into
728 an import of explicitly name object, or move the import* statement
729 to the global scope; to avoid the warning about bare exec, use
730 exec...in... (a good idea anyway -- there's a possibility that
731 bare exec will be deprecated in the future).
732
733 - Use of a global variable in a nested scope with the same name as a
734 local variable in a surrounding scope. This will change in
735 meaning with nested scopes: the name in the inner scope will
736 reference the variable in the outer scope rather than the global
737 of the same name. To avoid the warning, either rename the outer
738 variable, or use a global statement in the inner function.
739
Neil Schemenauera35c6882001-02-27 04:45:05 +0000740- An optional object allocator has been included. This allocator is
741 optimized for Python objects and should be faster and use less memory
742 than the standard system allocator. It is not enabled by default
743 because of possible thread safety problems. The allocator is only
744 protected by the Python interpreter lock and it is possible that some
745 extension modules require a thread safe allocator. The object
746 allocator can be enabled by providing the "--with-pymalloc" option to
747 configure.
748
Tim Petersd66595f2001-02-04 03:09:53 +0000749Standard library
750
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000751- pyexpat now detects the expat version if expat.h defines it. A
752 number of additional handlers are provided, which are only available
753 since expat 1.95. In addition, the methods SetParamEntityParsing and
754 GetInputContext of Parser objects are available with 1.95.x
755 only. Parser objects now provide the ordered_attributes and
756 specified_attributes attributes. A new module expat.model was added,
757 which offers a number of additional constants if 1.95.x is used.
758
759- xml.dom offers the new functions registerDOMImplementation and
760 getDOMImplementation.
761
762- xml.dom.minidom offers a toprettyxml method. A number of DOM
763 conformance issues have been resolved. In particular, Element now
764 has an hasAttributes method, and the handling of namespaces was
765 improved.
766
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000767- Ka-Ping Yee contributed two new modules: inspect.py, a module for
768 getting information about live Python code, and pydoc.py, a module
769 for interactively converting docstrings to HTML or text.
770 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000771 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000772 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
773 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000774
Tim Peters1eff7962001-03-01 02:31:33 +0000775- New library module difflib.py, primarily packaging the SequenceMatcher
776 class at the heart of the popular ndiff.py file-comparison tool.
777
778- doctest.py (a framework for verifying Python code examples in docstrings)
779 is now part of the std library.
780
Tim Petersd66595f2001-02-04 03:09:53 +0000781Windows changes
782
Guido van Rossume3955a82001-03-02 14:05:59 +0000783- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
784 small GUI that lets you browse the module docstrings using your
785 default web browser.
786
Tim Peters1eff7962001-03-01 02:31:33 +0000787- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
788 Platforms) is implemented. See
789
790 http://python.sourceforge.net/peps/pep-0235.html
791
792 for full details, especially the "Current Lower-Left Semantics" section.
793 The new Windows import rules are simpler than before:
794
795 A. If the PYTHONCASEOK environment variable exists, same as
796 before: silently accept the first case-insensitive match of any
797 kind; raise ImportError if none found.
798
799 B. Else search sys.path for the first case-sensitive match; raise
800 ImportError if none found.
801
802 The same rules have been implented on other platforms with case-
803 insensitive but case-preserving filesystems too (including Cygwin, and
804 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000805
Tim Peters25a9ce32001-02-19 07:06:36 +0000806- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
807 what it's supposed to do (and does do under NT and 2000) via direct
808 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000809 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000810 all Win9x systems before.
811
Tim Peters1eff7962001-03-01 02:31:33 +0000812- Build: Subproject _test (effectively) renamed to _testcapi.
813
Tim Peters2fe289a2001-03-01 22:19:38 +0000814New platforms
815
816- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
817 Thanks to Steven Majewski!
818
819- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
820 Tishler!
821
Guido van Rossum9089b272001-03-02 06:49:50 +0000822- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
823 Schwertberger! See RISCOS/README for more information -- it seems
824 that because of the bizarre filename conventions on RISCOS, no port
825 to that platform is easy. Note that the new variable os.endsep is
826 silently supported in order to make life easier on this platform,
827 but we don't advertise it because it's not worth for most folks to
828 care about RISCOS portability.
829
Tim Peters25a9ce32001-02-19 07:06:36 +0000830
Tim Petersd7b5e882001-01-25 03:36:26 +0000831What's New in Python 2.1 alpha 2?
832=================================
Tim Peters40ead762001-01-27 05:35:26 +0000833
Tim Petersd7b5e882001-01-25 03:36:26 +0000834Core language, builtins, and interpreter
835
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000836- Scopes nest. If a name is used in a function or class, but is not
837 local, the definition in the nearest enclosing function scope will
838 be used. One consequence of this change is that lambda statements
839 could reference variables in the namespaces where the lambda is
840 defined. In some unusual cases, this change will break code.
841
842 In all previous version of Python, names were resolved in exactly
843 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000844 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000845 function A is defined within a function B, the names bound in B are
846 not visible in A. The new rules make names bound in B visible in A,
847 unless A contains a name binding that hides the binding in B.
848
849 Section 4.1 of the reference manual describes the new scoping rules
850 in detail. The test script in Lib/test/test_scope.py demonstrates
851 some of the effects of the change.
852
853 The new rules will cause existing code to break if it defines nested
854 functions where an outer function has local variables with the same
855 name as globals or builtins used by the inner function. Example:
856
857 def munge(str):
858 def helper(x):
859 return str(x)
860 if type(str) != type(''):
861 str = helper(str)
862 return str.strip()
863
864 Under the old rules, the name str in helper() is bound to the
865 builtin function str(). Under the new rules, it will be bound to
866 the argument named str and an error will occur when helper() is
867 called.
868
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000869- The compiler will report a SyntaxError if "from ... import *" occurs
870 in a function or class scope. The language reference has documented
871 that this case is illegal, but the compiler never checked for it.
872 The recent introduction of nested scope makes the meaning of this
873 form of name binding ambiguous. In a future release, the compiler
874 may allow this form when there is no possibility of ambiguity.
875
Tim Peters40ead762001-01-27 05:35:26 +0000876- repr(string) is easier to read, now using hex escapes instead of octal,
877 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
878
879 >>> "\texample \r\n" + chr(0) + chr(255)
880 '\texample \r\n\x00\xff' # in 2.1
881 '\011example \015\012\000\377' # in 2.0
882
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000883- Functions are now compared and hashed by identity, not by value, since
884 the func_code attribute is writable.
885
Fred Drakefb9d7122001-02-01 20:00:40 +0000886- Weak references (PEP 205) have been added. This involves a few
887 changes in the core, an extension module (_weakref), and a Python
888 module (weakref). The weakref module is the public interface. It
889 includes support for "explicit" weak references, proxy objects, and
890 mappings with weakly held values.
891
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000892- A 'continue' statement can now appear in a try block within the body
893 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000894 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000895
Tim Petersd7b5e882001-01-25 03:36:26 +0000896Standard library
897
Barry Warsaw30dbd142001-01-31 22:14:01 +0000898- mailbox.py now has a new class, PortableUnixMailbox which is
899 identical to UnixMailbox but uses a more portable scheme for
900 determining From_ separators. Also, the constructors for all the
901 classes in this module have a new optional `factory' argument, which
902 is a callable used when new message classes must be instantiated by
903 the next() method.
904
Tim Petersd7b5e882001-01-25 03:36:26 +0000905- random.py is now self-contained, and offers all the functionality of
906 the now-deprecated whrandom.py. See the docs for details. random.py
907 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000908 and restoring the internal state of the generator; and jumpahead(n),
909 for quickly forcing the internal state to be the same as if n calls to
910 random() had been made. The latter is particularly useful for multi-
911 threaded programs, creating one instance of the random.Random() class for
912 each thread, then using .jumpahead() to force each instance to use a
913 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000914
Tim Peters0de88fc2001-02-01 04:59:18 +0000915- random.py's seed() function is new. For bit-for-bit compatibility with
916 prior releases, use the whseed function instead. The new seed function
917 addresses two problems: (1) The old function couldn't produce more than
918 about 2**24 distinct internal states; the new one about 2**45 (the best
919 that can be done in the Wichmann-Hill generator). (2) The old function
920 sometimes produced identical internal states when passed distinct
921 integers, and there was no simple way to predict when that would happen;
922 the new one guarantees to produce distinct internal states for all
923 arguments in [0, 27814431486576L).
924
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000925- The socket module now supports raw packets on Linux. The socket
926 family is AF_PACKET.
927
Tim Peters9ea17ac2001-02-02 05:57:15 +0000928- test_capi.py is a start at running tests of the Python C API. The tests
929 are implemented by the new Modules/_testmodule.c.
930
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000931- A new extension module, _symtable, provides provisional access to the
932 internal symbol table used by the Python compiler. A higher-level
933 interface will be added on top of _symtable in a future release.
934
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000935- Removed the obsolete soundex module.
936
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000937- xml.dom.minidom now uses the standard DOM exceptions. Node supports
938 the isSameNode method; NamedNodeMap the get method.
939
940- xml.sax.expatreader supports the lexical handler property; it
941 generates comment, startCDATA, and endCDATA events.
942
Tim Petersee826f82001-01-31 19:39:44 +0000943Windows changes
944
945- Build procedure: the zlib project is built in a different way that
946 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000947 the zlib binary used. See PCbuild\readme.txt for details. Your old
948 zlib-related directories can be deleted; you'll need to download fresh
949 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000950
Tim Peters9ea17ac2001-02-02 05:57:15 +0000951- Build: New subproject _test for the benefit of test_capi.py (see above).
952
Tim Petersb16c56f2001-02-02 21:24:51 +0000953- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
954 interface to some Python compiler internals).
955
956- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000957 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000958
Tim Petersa3a3a032000-11-30 05:22:44 +0000959What's New in Python 2.1 alpha 1?
960=================================
961
962Core language, builtins, and interpreter
963
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000964- There is a new Unicode companion to the PyObject_Str() API
965 called PyObject_Unicode(). It behaves in the same way as the
966 former, but assures that the returned value is an Unicode object
967 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000968
Guido van Rossumf98eda02001-01-17 15:54:45 +0000969- The comparison operators support "rich comparison overloading" (PEP
970 207). C extension types can provide a rich comparison function in
971 the new tp_richcompare slot in the type object. The cmp() function
972 and the C function PyObject_Compare() first try the new rich
973 comparison operators before trying the old 3-way comparison. There
974 is also a new C API PyObject_RichCompare() (which also falls back on
975 the old 3-way comparison, but does not constrain the outcome of the
976 rich comparison to a Boolean result).
977
978 The rich comparison function takes two objects (at least one of
979 which is guaranteed to have the type that provided the function) and
980 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
981 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
982 object, which may be NotImplemented (in which case the tp_compare
983 slot function is used as a fallback, if defined).
984
985 Classes can overload individual comparison operators by defining one
986 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000987 __ge__. There are no explicit "reflected argument" versions of
988 these; instead, __lt__ and __gt__ are each other's reflection,
989 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
990 reflection (similar at the C level). No other implications are
991 made; in particular, Python does not assume that == is the Boolean
992 inverse of !=, or that < is the Boolean inverse of >=. This makes
993 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000994
995 Classes or types that want to implement (in)equality tests but not
996 the ordering operators (i.e. unordered types) should implement ==
997 and !=, and raise an error for the ordering operators.
998
Guido van Rossuma88479f2001-01-18 14:28:08 +0000999 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +00001000 Boolean; e.g. a matrix type might want to return a matrix of bits
1001 for A < B, giving elementwise comparisons. Such types should ensure
1002 that any interpretation of their value in a Boolean context raises
1003 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
1004 at the C level) to always raise an exception.
1005
Guido van Rossuma88479f2001-01-18 14:28:08 +00001006- Complex numbers use rich comparisons to define == and != but raise
1007 an exception for <, <=, > and >=. Unfortunately, this also means
1008 that cmp() of two complex numbers raises an exception when the two
1009 numbers differ. Since it is not mathematically meaningful to compare
1010 complex numbers except for equality, I hope that this doesn't break
1011 too much code.
1012
Tim Peters3389f192001-02-18 08:48:49 +00001013- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +00001014 not defined by the language, other than that it's arbitrary but
1015 consistent (see the Reference Manual). An implementation detail changed
1016 in 2.1a1 such that None now compares less than any other object. Code
1017 relying on this new behavior (like code that relied on the previous
1018 behavior) does so at its own risk.
1019
Barry Warsaw573b5412001-01-15 20:43:18 +00001020- Functions and methods now support getting and setting arbitrarily
1021 named attributes (PEP 232). Functions have a new __dict__
1022 (a.k.a. func_dict) which hold the function attributes. Methods get
1023 and set attributes on their underlying im_func. It is a TypeError
1024 to set an attribute on a bound method.
1025
Guido van Rossum051e3352001-01-15 19:11:10 +00001026- The xrange() object implementation has been improved so that
1027 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1028 limitation that in this case len(xrange(sys.maxint)) can't be
1029 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1030 work fine as long as the index i doesn't actually reach 2**31.
1031 (Python uses regular ints for sequence and string indices; fixing
1032 that is much more work.)
1033
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001034- Two changes to from...import:
1035
Guido van Rossumba381232001-02-03 15:06:40 +00001036 1) "from M import X" now works even if (after loading module M)
1037 sys.modules['M'] is not a real module; it's basically a getattr()
1038 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001039
1040 2) "from M import *" now looks for M.__all__ to decide which names to
1041 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1042 filters out names starting with '_' as before. Whether or not
1043 __all__ exists, there's no restriction on the type of M.
1044
Guido van Rossumf61f1662001-01-10 20:13:55 +00001045- File objects have a new method, xreadlines(). This is the fastest
1046 way to iterate over all lines in a file:
1047
1048 for line in file.xreadlines():
1049 ...do something to line...
1050
1051 See the xreadlines module (mentioned below) for how to do this for
1052 other file-like objects.
1053
1054- Even if you don't use file.xreadlines(), you may expect a speedup on
1055 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001056 quite a bit in platform-specific ways: on systems (like Linux) that
1057 support flockfile(), getc_unlocked(), and funlockfile(), those are
1058 used by default. On systems (like Windows) without getc_unlocked(),
1059 a complicated (but still thread-safe) method using fgets() is used by
1060 default.
1061
Tim Petersd52269b2001-01-25 06:23:18 +00001062 You can force use of the fgets() method by #define'ing
1063 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001064 getc_unlocked()).
1065
Tim Petersd52269b2001-01-25 06:23:18 +00001066 You can force fgets() not to be used by #define'ing
1067 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001068 test_bufio.py fails -- and let us know if it does!).
1069
1070- In addition, the fileinput module, while still slower than the other
1071 methods on most platforms, has been sped up too, by using
1072 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001073
1074- Support for run-time warnings has been added, including a new
1075 command line option (-W) to specify the disposition of warnings.
1076 See the description of the warnings module below.
1077
1078- Extensive changes have been made to the coercion code. This mostly
1079 affects extension modules (which can now implement mixed-type
1080 numerical operators without having to use coercion), but
1081 occasionally, in boundary cases the coercion semantics have changed
1082 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001083 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001084 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001085 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001086
Guido van Rossumf98eda02001-01-17 15:54:45 +00001087- In connection with the coercion changes, a new built-in singleton
1088 object, NotImplemented is defined. This can be returned for
1089 operations that wish to indicate they are not implemented for a
1090 particular combination of arguments. From C, this is
1091 Py_NotImplemented.
1092
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001093- The interpreter accepts now bytecode files on the command line even
1094 if they do not have a .pyc or .pyo extension. On Linux, after executing
1095
Martin v. Löwise214baa2001-02-04 22:37:56 +00001096import imp,sys,string
1097magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1098reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1099open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001100
1101 any byte code file can be used as an executable (i.e. as an argument
1102 to execve(2)).
1103
Tim Peters9940b802000-12-01 07:59:35 +00001104- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001105 character. In 1.6 and earlier, they never produced a sign,
1106 and raised an error if the value of the long was too large
1107 to fit in a Python int. In 2.0, they produced a sign if and
1108 only if too large to fit in an int. This was inconsistent
1109 across platforms (because the size of an int varies across
1110 platforms), and inconsistent with hex() and oct(). Example:
1111
1112 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001113 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001114 'ffffffbe' # in 2.0 and before, on 32-bit machines
1115 >>> hex(-0x42L)
1116 '-0x42L' # in all versions of Python
1117
Tim Peters9940b802000-12-01 07:59:35 +00001118 The behavior of %d formats for negative Python longs remains
1119 the same as in 2.0 (although in 1.6 and before, they raised
1120 an error if the long didn't fit in a Python int).
1121
1122 %u formats don't make sense for Python longs, but are allowed
1123 and treated the same as %d in 2.1. In 2.0, a negative long
1124 formatted via %u produced a sign if and only if too large to
1125 fit in an int. In 1.6 and earlier, a negative long formatted
1126 via %u raised an error if it was too big to fit in an int.
1127
Guido van Rossum3661d392000-12-12 22:10:31 +00001128- Dictionary objects have an odd new method, popitem(). This removes
1129 an arbitrary item from the dictionary and returns it (in the form of
1130 a (key, value) pair). This can be useful for algorithms that use a
1131 dictionary as a bag of "to do" items and repeatedly need to pick one
1132 item. Such algorithms normally end up running in quadratic time;
1133 using popitem() they can usually be made to run in linear time.
1134
Tim Peters36cdad12000-12-29 02:06:45 +00001135Standard library
1136
Thomas Woutersfe385252001-01-19 23:16:56 +00001137- In the time module, the time argument to the functions strftime,
1138 localtime, gmtime, asctime and ctime is now optional, defaulting to
1139 the current time (in the local timezone).
1140
Guido van Rossumda91f222001-01-15 16:36:08 +00001141- The ftplib module now defaults to passive mode, which is deemed a
1142 more useful default given that clients are often inside firewalls
1143 these days. Note that this could break if ftplib is used to connect
1144 to a *server* that is inside a firewall, from outside; this is
1145 expected to be a very rare situation. To fix that, you can call
1146 ftp.set_pasv(0).
1147
Martin v. Löwis10a27872001-01-13 09:54:41 +00001148- The module site now treats .pth files not only for path configuration,
1149 but also supports extensions to the initialization code: Lines starting
1150 with import are executed.
1151
Guido van Rossumf61f1662001-01-10 20:13:55 +00001152- There's a new module, warnings, which implements a mechanism for
1153 issuing and filtering warnings. There are some new built-in
1154 exceptions that serve as warning categories, and a new command line
1155 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1156 turns warnings into errors). warnings.warn(message[, category])
1157 issues a warning message; this can also be called from C as
1158 PyErr_Warn(category, message).
1159
1160- A new module xreadlines was added. This exports a single factory
1161 function, xreadlines(). The intention is that this code is the
1162 absolutely fastest way to iterate over all lines in an open
1163 file(-like) object:
1164
1165 import xreadlines
1166 for line in xreadlines.xreadlines(file):
1167 ...do something to line...
1168
1169 This is equivalent to the previous the speed record holder using
1170 file.readlines(sizehint). Note that if file is a real file object
1171 (as opposed to a file-like object), this is equivalent:
1172
1173 for line in file.xreadlines():
1174 ...do something to line...
1175
Tim Peters36cdad12000-12-29 02:06:45 +00001176- The bisect module has new functions bisect_left, insort_left,
1177 bisect_right and insort_right. The old names bisect and insort
1178 are now aliases for bisect_right and insort_right. XXX_right
1179 and XXX_left methods differ in what happens when the new element
1180 compares equal to one or more elements already in the list: the
1181 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001182 right. Code that doesn't care where equal elements end up should
1183 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001184
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001185- The new curses.panel module wraps the panel library that forms part
1186 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1187
Guido van Rossumf61f1662001-01-10 20:13:55 +00001188- The SocketServer module now sets the allow_reuse_address flag by
1189 default in the TCPServer class.
1190
1191- A new function, sys._getframe(), returns the stack frame pointer of
1192 the caller. This is intended only as a building block for
1193 higher-level mechanisms such as string interpolation.
1194
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001195- The pyexpat module supports a number of new handlers, which are
1196 available only in expat 1.2. If invocation of a callback fails, it
1197 will report an additional frame in the traceback. Parser objects
1198 participate now in garbage collection. If expat reports an unknown
1199 encoding, pyexpat will try to use a Python codec; that works only
1200 for single-byte charsets. The parser type objects is exposed as
1201 XMLParserObject.
1202
1203- xml.dom now offers standard definitions for symbolic node type and
1204 exception code constants, and a hierarchy of DOM exceptions. minidom
1205 was adjusted to use them.
1206
1207- The conformance of xml.dom.minidom to the DOM specification was
1208 improved. It detects a number of additional error cases; the
1209 previous/next relationship works even when the tree is modified;
1210 Node supports the normalize() method; NamedNodeMap, DocumentType and
1211 DOMImplementation classes were added; Element supports the
1212 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1213 method.
1214
Guido van Rossumf61f1662001-01-10 20:13:55 +00001215Build issues
1216
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001217- For Unix (and Unix-compatible) builds, configuration and building of
1218 extension modules is now greatly automated. Rather than having to
1219 edit the Modules/Setup file to indicate which modules should be
1220 built and where their include files and libraries are, a
1221 distutils-based setup.py script now takes care of building most
1222 extension modules. All extension modules built this way are built
1223 as shared libraries. Only a few modules that must be linked
1224 statically are still listed in the Setup file; you won't need to
1225 edit their configuration.
1226
1227- Python should now build out of the box on Cygwin. If it doesn't,
1228 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001229
1230- Python now always uses its own (renamed) implementation of getopt()
1231 -- there's too much variation among C library getopt()
1232 implementations.
1233
1234- C++ compilers are better supported; the CXX macro is always set to a
1235 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001236
Tim Petersd92dfe02000-12-12 01:18:41 +00001237Windows changes
1238
1239- select module: By default under Windows, a select() call
1240 can specify no more than 64 sockets. Python now boosts
1241 this Microsoft default to 512. If you need even more than
1242 that, see the MS docs (you'll need to #define FD_SETSIZE
1243 and recompile Python from source).
1244
Guido van Rossumf61f1662001-01-10 20:13:55 +00001245- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1246 subdirectory is no more!
1247
Tim Petersa3a3a032000-11-30 05:22:44 +00001248
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001249What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001250=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001251
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001252Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001253changes are in the file HISTORY. If you are making the jump directly
1254from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1255HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001256
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001257Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1258the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1259http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001260
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001261--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001262
1263======================================================================
1264
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001265What's new in 2.0 (since release candidate 1)?
1266==============================================
1267
1268Standard library
1269
1270- The copy_reg module was modified to clarify its intended use: to
1271 register pickle support for extension types, not for classes.
1272 pickle() will raise a TypeError if it is passed a class.
1273
1274- Fixed a bug in gettext's "normalize and expand" code that prevented
1275 it from finding an existing .mo file.
1276
1277- Restored support for HTTP/0.9 servers in httplib.
1278
Tim Peters989b7b92000-10-16 20:24:53 +00001279- The math module was changed to stop raising OverflowError in case of
1280 underflow, and return 0 instead in underflow cases. Whether Python
1281 used to raise OverflowError in case of underflow was platform-
1282 dependent (it did when the platform math library set errno to ERANGE
1283 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001284
1285- Fixed a bug in StringIO that occurred when the file position was not
1286 at the end of the file and write() was called with enough data to
1287 extend past the end of the file.
1288
1289- Fixed a bug that caused Tkinter error messages to get lost on
1290 Windows. The bug was fixed by replacing direct use of
1291 interp->result with Tcl_GetStringResult(interp).
1292
1293- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1294 redirect response.
1295
1296- Several changes were made to distutils: Some debugging code was
1297 removed from util. Fixed the installer used when an external zip
1298 program (like WinZip) is not found; the source code for this
1299 installer is in Misc/distutils. check_lib() was modified to behave
1300 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1301 test for whether installed modules are on sys.path was changed to
1302 use both normcase() and normpath().
1303
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001304- Several minor bugs were fixed in the xml package (the minidom,
1305 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001306
1307- The regression test driver (regrtest.py) behavior when invoked with
1308 -l changed: It now reports a count of objects that are recognized as
1309 garbage but not freed by the garbage collector.
1310
Tim Peters989b7b92000-10-16 20:24:53 +00001311- The regression test for the math module was changed to test
1312 exceptional behavior when the test is run in verbose mode. Python
1313 cannot yet guarantee consistent exception behavior across platforms,
1314 so the exception part of test_math is run only in verbose mode, and
1315 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001316
1317Internals
1318
1319- PyOS_CheckStack() has been disabled on Win64, where it caused
1320 test_sre to fail.
1321
1322Build issues
1323
1324- Changed compiler flags, so that gcc is always invoked with -Wall and
1325 -Wstrict-prototypes. Users compiling Python with GCC should see
1326 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001327 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001328 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001329
Tim Petersa3a3a032000-11-30 05:22:44 +00001330- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001331
1332Tools and other miscellany
1333
1334- The compiler in Tools/compiler was updated to support the new
1335 language features introduced in 2.0: extended print statement, list
1336 comprehensions, and augmented assignments. The new compiler should
1337 also be backwards compatible with Python 1.5.2; the compiler will
1338 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001339 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001340
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001341What's new in 2.0 release candidate 1 (since beta 2)?
1342=====================================================
1343
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001344What is release candidate 1?
1345
1346We believe that release candidate 1 will fix all known bugs that we
1347intend to fix for the 2.0 final release. This release should be a bit
1348more stable than the previous betas. We would like to see even more
1349widespread testing before the final release, so we are producing this
1350release candidate. The final release will be exactly the same unless
1351any show-stopping (or brown bag) bugs are found by testers of the
1352release candidate.
1353
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001354All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001355to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001356
1357Core language, builtins, and interpreter
1358
1359- A bug that caused crashes when __coerce__ was used with augmented
1360 assignment, e.g. +=, was fixed.
1361
1362- Raise ZeroDivisionError when raising zero to a negative number,
1363 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1364 power operator and the result of math.pow(0.0, -2.0) will vary by
1365 platform. On Linux, it raises a ValueError.
1366
1367- A bug in Unicode string interpolation was fixed that occasionally
1368 caused errors with formats including "%%". For example, the
1369 following expression "%% %s" % u"abc" no longer raises a TypeError.
1370
1371- Compilation of deeply nested expressions raises MemoryError instead
1372 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1373
1374- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1375 rendering them useless. They are now written in binary mode again.
1376
1377Standard library
1378
1379- Keyword arguments are now accepted for most pattern and match object
1380 methods in SRE, the standard regular expression engine.
1381
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001382- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001383 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001384
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001385- Several bugs in the Unicode handling and error handling in _tkinter
1386 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001387
1388- Fix memory management errors in Merge() and Tkapp_Call() routines.
1389
1390- Several changes were made to cStringIO to make it compatible with
1391 the file-like object interface and with StringIO. If operations are
1392 performed on a closed object, an exception is raised. The truncate
1393 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001394 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001395
1396- There were many changes made to the linuxaudiodev module and its
1397 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001398 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001399
1400 Note that this module is named poorly, because it should work
1401 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001402 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001403
1404 The module now raises exceptions when errors occur instead of
1405 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1406 audio) and defines a getptr() method that calls the
1407 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1408
1409- The library_version attribute, introduced in an earlier beta, was
1410 removed because it can not be supported with early versions of the C
1411 readline library, which provides no way to determine the version at
1412 compile-time.
1413
1414- The binascii module is now enabled on Win64.
1415
Tim Peters46446d62000-10-09 21:19:31 +00001416- tokenize.py no longer suffers "recursion depth" errors when parsing
1417 programs with very long string literals.
1418
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001419Internals
1420
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001421- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001422 which is called when the interpreter starts up to determine where
1423 the standard library is installed. These vulnerabilities affect all
1424 previous versions of Python and can be exploited by setting very
1425 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1426 setuid Python script, although use of the wrapper in
1427 Misc/setuid-prog.c will eliminate the vulnerability.
1428
1429- Fixed garbage collection bugs in instance creation that were
1430 triggered when errors occurred during initialization. The solution,
1431 applied in cPickle and in PyInstance_New(), is to call
1432 PyObject_GC_Init() after the initialization of the object's
1433 container attributes is complete.
1434
1435- pyexpat adds definitions of PyModule_AddStringConstant and
1436 PyModule_AddObject if the Python version is less than 2.0, which
1437 provides compatibility with PyXML on Python 1.5.2.
1438
1439- If the platform has a bogus definition for LONG_BIT (the number of
1440 bits in a long), an error will be reported at compile time.
1441
1442- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1443 collection crashes and possibly other, unreported crashes.
1444
1445- Fixed a memory leak in _PyUnicode_Fini().
1446
1447Build issues
1448
1449- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001450 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001451 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001452
1453- The mmap.PAGESIZE constant is now initialized using sysconf when
1454 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1455
1456- The md5 file should now compile on all platforms.
1457
1458- The select module now compiles on platforms that do not define
1459 POLLRDNORM and related constants.
1460
1461- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001462 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001463
Jeremy Hylton10921202000-10-09 18:34:12 +00001464- BeOS: A number of changes were made to the build and installation
1465 process. ar-fake now operates on a directory of object files.
1466 dl_export.h is gone, and its macros now appear on the mwcc command
1467 line during build on PPC BeOS.
1468
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001469- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001470 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001471
1472- Cygwin: Support for shared libraries, Tkinter, and sockets.
1473
1474- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1475
1476Tools and other miscellany
1477
1478- Removed debugging prints from main used with freeze.
1479
Tim Peters46446d62000-10-09 21:19:31 +00001480- IDLE auto-indent no longer crashes when it encounters Unicode
1481 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001482
1483What's new in 2.0 beta 2 (since beta 1)?
1484========================================
1485
1486Core language, builtins, and interpreter
1487
Tim Peters482c0212000-09-26 06:33:09 +00001488- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001489 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001490
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001491- Add -h and -V command line options to print the usage message and
1492 Python version number and exit immediately.
1493
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001494- eval() and exec accept Unicode objects as code parameters.
1495
1496- getattr() and setattr() now also accept Unicode objects for the
1497 attribute name, which are converted to strings using the default
1498 encoding before lookup.
1499
1500- Multiplication on string and Unicode now does proper bounds
1501 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1502 string is too long."
1503
1504- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001505 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001506
Jeremy Hylton1b618592000-09-26 05:32:36 +00001507
1508Standard library and extensions
1509
Guido van Rossum5b08f132001-04-16 02:05:23 +00001510- socket module: the OpenSSL code now adds support for RAND_status()
1511 and EGD (Entropy Gathering Device).
1512
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001513- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001514 argument checking; it still takes no arguments.
1515
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001516- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001517
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001518- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001519
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001520- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001521
1522- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001523 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001524
1525- copy: Copy Unicode objects atomically.
1526
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001527- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001528
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001529- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001530
Fred Drake67233bc2000-09-26 16:40:27 +00001531- dbm: Add get() and setdefault() methods to dbm object. Add constant
1532 `library' to module that names the library used. Added doc strings
1533 and method names to error messages. Uses configure to determine
1534 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1535 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001536
1537- distutils: Update to version 0.9.3.
1538
1539- dl: Add several dl.RTLD_ constants.
1540
1541- fpectl: Now supported on FreeBSD.
1542
1543- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1544 found by the collector will be saved in gc.garbage. This is useful
1545 for debugging a program that creates reference cycles.
1546
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001547- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001548 of HTTP class. Do not close socket on zero-length response. Do not
1549 crash when server sends invalid content-length header.
1550
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001551- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001552
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001553- marshal: When reading a short, sign-extend on platforms where shorts
1554 are bigger than 16 bits. When reading a long, repair the unportable
1555 sign extension that was being done for 64-bit machines. (It assumed
1556 that signed right shift sign-extends.)
1557
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001558- operator: Add contains(), invert(), __invert__() as aliases for
1559 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001560
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001561- os: Add support for popen2() and popen3() on all platforms where
1562 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001563
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001564- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001565 clicking on a file in Explorer (or passing the file name to the
1566 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001567
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001568- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001569 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001570
1571- pickle: Now raises ValueError when an invalid pickle that contains
1572 a non-string repr where a string repr was expected. This behavior
1573 matches cPickle.
1574
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001575- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001576
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001577- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001578
1579- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001580 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001581 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001582
1583- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001584 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001585
1586- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001587 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001588 few cycles during startup since the first call to
1589 setdefaultencoding() will initialize the codec registry and the
1590 encodings package.
1591
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001592- socket: Support for size hint in readlines() method of object returned
1593 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001594
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001595- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001596 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001597 is followed by whitespace.
1598
Tim Petersa3a3a032000-11-30 05:22:44 +00001599- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001600
1601- struct: Check ranges for bytes and shorts.
1602
1603- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001604 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001605
1606- Tkinter: Image objects are now guaranteed to have unique ids. Set
1607 event.delta to zero if Tk version doesn't support mousewheel.
1608 Removed some debugging prints.
1609
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001610- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001611
Fred Drake67233bc2000-09-26 16:40:27 +00001612- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001613 which works around a bug in Norton AntiVirus 2000 that leads directly
1614 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001615
1616- xml: New version detection code allows PyXML to override standard
1617 XML package if PyXML version is greater than 0.6.1.
1618
Fred Drake64bb3802000-09-26 16:21:35 +00001619- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1620 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1621 tree only for nodes which are sufficiently interesting to a specific
1622 application. Does not provide the HTML-specific extensions. Still
1623 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001624
Fred Drake64bb3802000-09-26 16:21:35 +00001625- xml.sax: SAX 2 support for Python, including all the handler
1626 interfaces needed to process XML 1.0 compliant XML. Some
1627 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001628
Fred Drake64bb3802000-09-26 16:21:35 +00001629- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1630 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001631
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001632
Jeremy Hylton1b618592000-09-26 05:32:36 +00001633C API
1634
1635- Add three new convenience functions for module initialization --
1636 PyModule_AddObject(), PyModule_AddIntConstant(), and
1637 PyModule_AddStringConstant().
1638
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001639- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001640 removed and add #error to Python.h if NULL isn't defined after
1641 #include of stdio.h.
1642
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001643- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001644 backwards compatibility (at the source level) with old extensions.
1645
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001646- A wrapper API was added for signal() and sigaction(). Instead of
1647 either function, always use PyOS_getsig() to get a signal handler
1648 and PyOS_setsig() to set one. A new convenience typedef
1649 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001650
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001651- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001652 internal data buffer and size of a string object -- or the default
1653 encoded version of a Unicode object.
1654
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001655- PyString_Size() and PyString_AsString() accept Unicode objects.
1656
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001657- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001658 exists). INT_MAX and LONG_MAX will always be defined, even if
1659 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001660
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001661- PyFloat_FromString takes a second argument, pend, that was
1662 effectively useless. It is now officially useless but preserved for
1663 backwards compatibility. If the pend argument is not NULL, *pend is
1664 set to NULL.
1665
1666- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1667 for the attribute name. See note on getattr() above.
1668
1669- A few bug fixes to argument processing for Unicode.
1670 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1671 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1672 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001673 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001674
1675- Py_BuildValue accepts B format (for bgen-generated code).
1676
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001677
Jeremy Hylton1b618592000-09-26 05:32:36 +00001678Internals
1679
1680- On Unix, fix code for finding Python installation directory so that
1681 it works when argv[0] is a relative path.
1682
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001683- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001684 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001685 rather than by generating a copy of the object.
1686
Tim Peters482c0212000-09-26 06:33:09 +00001687- Several of the internal Unicode tables are much smaller now, and
1688 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001689
Jeremy Hylton97693b02000-09-26 17:42:51 +00001690- In the garbage collector: Fixed bug in collection of tuples. Fixed
1691 bug that caused some instances to be removed from the container set
1692 while they were still live. Fixed parsing in gc.set_debug() for
1693 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001694
1695- Fixed refcount problem in instance deallocation that only occurred
1696 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1697
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001698- On Windows, getpythonregpath is now protected against null data in
1699 registry key.
1700
1701- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001702 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001703
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001704
Jeremy Hylton1b618592000-09-26 05:32:36 +00001705Build and platform-specific issues
1706
1707- Better support of GNU Pth via --with-pth configure option.
1708
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001709- Python/C API now properly exposed to dynamically-loaded extension
1710 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001711
1712- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1713 Don't define MS_SYNC to be zero when it is undefined. Added missing
1714 prototypes in posixmodule.c.
1715
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001716- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001717 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001718
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001719- Fix largefile support on older NetBSD systems and OpenBSD by adding
1720 define for TELL64.
1721
1722
1723Tools and other miscellany
1724
1725- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1726
1727- freeze: The modulefinder now works with 2.0 opcodes.
1728
Tim Petersa3a3a032000-11-30 05:22:44 +00001729- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001730 Move hackery of sys.argv until after the Tk instance has been
1731 created, which allows the application-specific Tkinter
1732 initialization to be executed if present; also pass an explicit
1733 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001734
Jeremy Hylton1b618592000-09-26 05:32:36 +00001735
1736What's new in 2.0 beta 1?
1737=========================
1738
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001739Source Incompatibilities
1740------------------------
1741
1742None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1743such as single-argument append(), connect() and bind(), and changes to
1744str(long) and repr(float).
1745
1746
1747Binary Incompatibilities
1748------------------------
1749
1750- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1751with Python 2.0; these extensions will have to be rebuilt for Python
17522.0.
1753
1754- On Windows, attempting to import a third party extension built for
1755Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1756can do about this. Check your PYTHONPATH environment variable!
1757
1758- Python bytecode files (*.pyc and *.pyo) are not compatible between
1759releases.
1760
1761
1762Overview of Changes Since 1.6
1763-----------------------------
1764
1765There are many new modules (including brand new XML support through
1766the xml package, and i18n support through the gettext module); a list
1767of all new modules is included below. Lots of bugs have been fixed.
1768
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001769The process for making major new changes to the language has changed
1770since Python 1.6. Enhancements must now be documented by a Python
1771Enhancement Proposal (PEP) before they can be accepted.
1772
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001773There are several important syntax enhancements, described in more
1774detail below:
1775
1776 - Augmented assignment, e.g. x += 1
1777
1778 - List comprehensions, e.g. [x**2 for x in range(10)]
1779
1780 - Extended import statement, e.g. import Module as Name
1781
1782 - Extended print statement, e.g. print >> file, "Hello"
1783
1784Other important changes:
1785
1786 - Optional collection of cyclical garbage
1787
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001788Python Enhancement Proposal (PEP)
1789---------------------------------
1790
1791PEP stands for Python Enhancement Proposal. A PEP is a design
1792document providing information to the Python community, or describing
1793a new feature for Python. The PEP should provide a concise technical
1794specification of the feature and a rationale for the feature.
1795
1796We intend PEPs to be the primary mechanisms for proposing new
1797features, for collecting community input on an issue, and for
1798documenting the design decisions that have gone into Python. The PEP
1799author is responsible for building consensus within the community and
1800documenting dissenting opinions.
1801
1802The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001803
1804Augmented Assignment
1805--------------------
1806
1807This must have been the most-requested feature of the past years!
1808Eleven new assignment operators were added:
1809
Guido van Rossume905e952000-09-05 12:42:46 +00001810 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001811
1812For example,
1813
1814 A += B
1815
1816is similar to
1817
1818 A = A + B
1819
1820except that A is evaluated only once (relevant when A is something
1821like dict[index].attr).
1822
1823However, if A is a mutable object, A may be modified in place. Thus,
1824if A is a number or a string, A += B has the same effect as A = A+B
1825(except A is only evaluated once); but if a is a list, A += B has the
1826same effect as A.extend(B)!
1827
1828Classes and built-in object types can override the new operators in
1829order to implement the in-place behavior; the not-in-place behavior is
1830used automatically as a fallback when an object doesn't implement the
1831in-place behavior. For classes, the method name is derived from the
1832method name for the corresponding not-in-place operator by inserting
1833an 'i' in front of the name, e.g. __iadd__ implements in-place
1834__add__.
1835
1836Augmented assignment was implemented by Thomas Wouters.
1837
1838
1839List Comprehensions
1840-------------------
1841
1842This is a flexible new notation for lists whose elements are computed
1843from another list (or lists). The simplest form is:
1844
1845 [<expression> for <variable> in <sequence>]
1846
Guido van Rossum56db0952000-09-06 23:34:25 +00001847For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001848This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001849
1850You can also add a condition:
1851
1852 [<expression> for <variable> in <sequence> if <condition>]
1853
1854For example, [w for w in words if w == w.lower()] would yield the list
1855of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001856than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001857
1858You can also have nested for loops and more than one 'if' clause. For
1859example, here's a function that flattens a sequence of sequences::
1860
1861 def flatten(seq):
1862 return [x for subseq in seq for x in subseq]
1863
1864 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1865
1866This prints
1867
1868 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1869
1870List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001871Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001872
1873
1874Extended Import Statement
1875-------------------------
1876
1877Many people have asked for a way to import a module under a different
1878name. This can be accomplished like this:
1879
1880 import foo
1881 bar = foo
1882 del foo
1883
1884but this common idiom gets old quickly. A simple extension of the
1885import statement now allows this to be written as follows:
1886
1887 import foo as bar
1888
1889There's also a variant for 'from ... import':
1890
1891 from foo import bar as spam
1892
1893This also works with packages; e.g. you can write this:
1894
1895 import test.regrtest as regrtest
1896
1897Note that 'as' is not a new keyword -- it is recognized only in this
1898context (this is only possible because the syntax for the import
1899statement doesn't involve expressions).
1900
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001901Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001902
1903
1904Extended Print Statement
1905------------------------
1906
1907Easily the most controversial new feature, this extension to the print
1908statement adds an option to make the output go to a different file
1909than the default sys.stdout.
1910
1911For example, to write an error message to sys.stderr, you can now
1912write:
1913
1914 print >> sys.stderr, "Error: bad dog!"
1915
1916As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001917evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001918
1919 print >> None, "Hello world"
1920
1921is equivalent to
1922
1923 print "Hello world"
1924
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001925Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001926
1927
1928Optional Collection of Cyclical Garbage
1929---------------------------------------
1930
1931Python is now equipped with a garbage collector that can hunt down
1932cyclical references between Python objects. It's no replacement for
1933reference counting; in fact, it depends on the reference counts being
1934correct, and decides that a set of objects belong to a cycle if all
1935their reference counts can be accounted for from their references to
1936each other. This devious scheme was first proposed by Eric Tiedemann,
1937and brought to implementation by Neil Schemenauer.
1938
1939There's a module "gc" that lets you control some parameters of the
1940garbage collection. There's also an option to the configure script
1941that lets you enable or disable the garbage collection. In 2.0b1,
1942it's on by default, so that we (hopefully) can collect decent user
1943experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001944performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001945off by default in the final 2.0 release.
1946
1947
1948Smaller Changes
1949---------------
1950
1951A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1952map(None, seq1, seq2, ...) when the sequences have the same length;
1953i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1954the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001955zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001956
1957sys.version_info is a tuple (major, minor, micro, level, serial).
1958
1959Dictionaries have an odd new method, setdefault(key, default).
1960dict.setdefault(key, default) returns dict[key] if it exists; if not,
1961it sets dict[key] to default and returns that value. Thus:
1962
1963 dict.setdefault(key, []).append(item)
1964
1965does the same work as this common idiom:
1966
1967 if not dict.has_key(key):
1968 dict[key] = []
1969 dict[key].append(item)
1970
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001971There are two new variants of SyntaxError that are raised for
1972indentation-related errors: IndentationError and TabError.
1973
1974Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1975escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001976
1977The limits on the size of expressions and file in Python source code
1978have been raised from 2**16 to 2**32. Previous versions of Python
1979were limited because the maximum argument size the Python VM accepted
1980was 2**16. This limited the size of object constructor expressions,
1981e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1982limit was raised thanks to a patch by Charles Waldman that effectively
1983fixes the problem. It is now much more likely that you will be
1984limited by available memory than by an arbitrary limit in Python.
1985
1986The interpreter's maximum recursion depth can be modified by Python
1987programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1988limit is the maximum number of recursive calls that can be made by
1989Python code. The limit exists to prevent infinite recursion from
1990overflowing the C stack and causing a core dump. The default value is
19911000. The maximum safe value for a particular platform can be found
1992by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001993
1994New Modules and Packages
1995------------------------
1996
1997atexit - for registering functions to be called when Python exits.
1998
1999imputil - Greg Stein's alternative API for writing custom import
2000hooks.
2001
2002pyexpat - an interface to the Expat XML parser, contributed by Paul
2003Prescod.
2004
2005xml - a new package with XML support code organized (so far) in three
2006subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
2007would fill a volume. There's a special feature whereby a
2008user-installed package named _xmlplus overrides the standard
2009xmlpackage; this is intended to give the XML SIG a hook to distribute
2010backwards-compatible updates to the standard xml package.
2011
2012webbrowser - a platform-independent API to launch a web browser.
2013
2014
Guido van Rossume905e952000-09-05 12:42:46 +00002015Changed Modules
2016---------------
2017
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002018array -- new methods for array objects: count, extend, index, pop, and
2019remove
2020
2021binascii -- new functions b2a_hex and a2b_hex that convert between
2022binary data and its hex representation
2023
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002024calendar -- Many new functions that support features including control
2025over which day of the week is the first day, returning strings instead
2026of printing them. Also new symbolic constants for days of week,
2027e.g. MONDAY, ..., SUNDAY.
2028
2029cgi -- FieldStorage objects have a getvalue method that works like a
2030dictionary's get method and returns the value attribute of the object.
2031
2032ConfigParser -- The parser object has new methods has_option,
2033remove_section, remove_option, set, and write. They allow the module
2034to be used for writing config files as well as reading them.
2035
2036ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002037optionally support the RFC 959 REST command.
2038
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002039gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002040
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002041httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2042the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002043
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002044locale -- implement getdefaultlocale for Win32 and Macintosh
2045
2046marshal -- no longer dumps core when marshaling deeply nested or
2047recursive data structures
2048
2049os -- new functions isatty, seteuid, setegid, setreuid, setregid
2050
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002051os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2052support under Unix.
2053
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002054os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002055
2056os.path -- fix semantics of os.path.commonprefix
2057
2058smtplib -- support for sending very long messages
2059
2060socket -- new function getfqdn()
2061
2062readline -- new functions to read, write and truncate history files.
2063The readline section of the library reference manual contains an
2064example.
2065
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002066select -- add interface to poll system call
2067
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002068shutil -- new copyfileobj function
2069
2070SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2071HTTP server.
2072
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002073Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002074
2075urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002076e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002077
2078whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002079
2080
2081Obsolete Modules
2082----------------
2083
2084None. However note that 1.6 made a whole slew of modules obsolete:
2085stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2086poly, zmod, strop, util, whatsound.
2087
2088
2089Changed, New, Obsolete Tools
2090----------------------------
2091
Tim Peters8b092332000-09-05 20:15:25 +00002092None.
Guido van Rossume905e952000-09-05 12:42:46 +00002093
2094
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002095C-level Changes
2096---------------
2097
2098Several cleanup jobs were carried out throughout the source code.
2099
2100All C code was converted to ANSI C; we got rid of all uses of the
2101Py_PROTO() macro, which makes the header files a lot more readable.
2102
2103Most of the portability hacks were moved to a new header file,
2104pyport.h; several other new header files were added and some old
2105header files were removed, in an attempt to create a more rational set
2106of header files. (Few of these ever need to be included explicitly;
2107they are all included by Python.h.)
2108
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002109Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002110and Win64, especially for the new Intel Itanium processor. Mick also
2111added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002112
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002113The C APIs to return an object's size have been update to consistently
2114use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2115previous versions, the abstract interfaces used PyXXX_Length and the
2116concrete interfaces used PyXXX_Size. The old names,
2117e.g. PyObject_Length, are still available for backwards compatibility
2118at the API level, but are deprecated.
2119
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002120The PyOS_CheckStack function has been implemented on Windows by
2121Fredrik Lundh. It prevents Python from failing with a stack overflow
2122on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002123
2124The GC changes resulted in creation of two new slots on object,
2125tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002126the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002127
2128The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002129C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002130
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002131PyErr_Format has been updated to automatically calculate the size of
2132the buffer needed to hold the formatted result string. This change
2133prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002134
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002135New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002136
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002137PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2138that are the same as their non-Ex counterparts except they take an
2139extra flag argument that tells them to close the file when done.
2140
2141XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002142
Tim Peters8b092332000-09-05 20:15:25 +00002143
2144Windows Changes
2145---------------
2146
2147New popen2/popen3/peopen4 in os module (see Changed Modules above).
2148
2149os.popen is much more usable on Windows 95 and 98. See Microsoft
2150Knowledge Base article Q150956. The Win9x workaround described there
2151is implemented by the new w9xpopen.exe helper in the root of your
2152Python installation. Note that Python uses this internally; it is not
2153a standalone program.
2154
2155Administrator privileges are no longer required to install Python
2156on Windows NT or Windows 2000. If you have administrator privileges,
2157Python's registry info will be written under HKEY_LOCAL_MACHINE.
2158Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002159under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002160uses of Python, but will prevent some advanced uses from working
2161(for example, running a Python script as an NT service, or possibly
2162from CGI).
2163
2164[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2165installer; instead, it installs the needed Tcl/Tk files directly in the
2166Python directory. If you already have a Tcl/Tk installation, this
2167wastes some disk space (about 4 Megs) but avoids problems with
2168conflicting Tcl/Tk installations, and makes it much easier for Python
2169to ensure that Tcl/Tk can find all its files.
2170
2171[This was new in 1.6] The Windows installer now installs by default in
2172\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2173
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002174
2175Updates to the changes between 1.5.2 and 1.6
2176--------------------------------------------
2177
2178The 1.6 NEWS file can't be changed after the release is done, so here
2179is some late-breaking news:
2180
2181New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2182and changes to getlocale() and setlocale().
2183
2184The new module is now enabled per default.
2185
2186It is not true that the encodings codecs cannot be used for normal
2187strings: the string.encode() (which is also present on 8-bit strings
2188!) allows using them for 8-bit strings too, e.g. to convert files from
2189cp1252 (Windows) to latin-1 or vice-versa.
2190
2191Japanese codecs are available from Tamito KAJIYAMA:
2192http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2193
2194
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002195======================================================================