blob: 7151caa4aea2002f8e94654e8d7e8cc9b67388e1 [file] [log] [blame]
Tim Peters20f51a72001-07-21 02:31:40 +00001What's New in Python 2.2a2?
2===========================
3
Martin v. Löwis339d0f72001-08-17 18:39:25 +00004Build
5
Barry Warsaw18b2ecf2001-08-22 20:26:56 +00006- Tim Peters developed a brand new Windows installer using Wise 8.1,
7 generously donated to us by Wise Solutions.
8
Martin v. Löwis339d0f72001-08-17 18:39:25 +00009- configure supports a new option --enable-unicode, with the values
10 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
11 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +000012
Jack Jansen32ce0cd2001-08-21 19:28:20 +000013- A new configure option --enable-framework builds a Mac OS X framework,
14 which "make frameworkinstall" will install. This provides a starting
15 point for more mac-like functionality, join pythonmac-sig@python.org
16 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +000017
Barry Warsaw6f3410d2001-08-22 04:08:41 +000018- The NeXT platform is no longer supported.
19
20- The `new' module is now statically linked.
21
Tim Peters0afb6092001-08-15 06:06:44 +000022Tools
23
24- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +000025 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +000026 the module docstring for details.
27
Tim Peters20f51a72001-07-21 02:31:40 +000028Tests
29
Tim Peters5e824c32001-08-12 22:25:01 +000030- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +000031 platforms, allowing to give clearer test result output. regrtest
32 also has optional --use/-u switch to run normally disabled tests
33 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +000034
Tim Peters20f51a72001-07-21 02:31:40 +000035- Several new tests in the standard test suite, with special thanks to
36 Nick Mathewson.
37
38Core
39
Barry Warsaw6f3410d2001-08-22 04:08:41 +000040- The floor division operator // has been added as outlined in PEP
41 238. The / operator still provides classic division (and will until
42 Python 3.0) unless "from __future__ import division" is included, in
43 which case the / operator will provide true division. The operator
44 module provides truediv() and floordiv() functions. Augmented
45 assignment variants are included, as are the equivalent overloadable
46 methods and C API methods. See the PEP for a full discussion:
47 <http://python.sf.net/peps/pep-0238.html>
48
Tim Peters6cd6a822001-08-17 22:11:27 +000049- Future statements are now effective in simulated interactive shells
50 (like IDLE). This should "just work" by magic, but read Michael
51 Hudson's "Future statements in simulated shells" PEP 264 for full
52 details: <http://python.sf.net/peps/pep-0264.html>.
53
Guido van Rossumf86ddd22001-08-17 21:21:04 +000054- The type/class unification (PEP 252-253) was integrated into the
55 trunk and is not so tentative any more (the exact specification of
56 some features is still tentative). A lot of work has done on fixing
57 bugs and adding robustness and features (performance still has to
58 come a long way).
59
Marc-André Lemburg888fac02001-07-31 14:24:31 +000060- Warnings about a mismatch in the Python API during extension import
61 now use the Python warning framework (which makes it possible to
62 write filters for these warnings).
63
Barry Warsaw9b3be7f2001-08-14 18:35:02 +000064- A function's __dict__ (aka func_dict) will now always be a
65 dictionary. It used to be possible to delete it or set it to None,
66 but now both actions raise TypeErrors. It is still legal to set it
67 to a dictionary object. Getting func.__dict__ before any attributes
68 have been assigned now returns an empty dictionary instead of None.
69
Marc-André Lemburgd6277912001-07-31 14:42:42 +000070Library
71
Tim Peters5e824c32001-08-12 22:25:01 +000072- New class Differ and new functions ndiff() and restore() in difflib.py.
73 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +000074 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +000075
Marc-André Lemburgd6277912001-07-31 14:42:42 +000076- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
77 value using the minimal quoting required for the value; more
78 reliable than using xml.sax.saxutils.escape() for attribute values.
79
80- Readline completion support for cmd.Cmd was added.
81
Barry Warsaw6f3410d2001-08-22 04:08:41 +000082- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
83
84- Added function threading.BoundedSemaphore()
85
86- Added Ka-Ping Yee's cgitb.py module.
87
88- The `new' module now exposes the CO_xxx flags.
89
Marc-André Lemburgd6277912001-07-31 14:42:42 +000090New platforms
91
92C API
93
Marc-André Lemburg888fac02001-07-31 14:24:31 +000094- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
95 which provide a cross-platform implementations for the
96 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
97 the standard sprintf() and vsprintf() C lib APIs, these versions
98 apply bounds checking on the used buffer which enhances protection
99 against buffer overruns.
100
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000101- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000102 and extensions using different Unicode widths is rendered next to
103 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000104 will result in an ImportError. Unicode extensions writers must make
105 sure to check the Unicode width compatibility in their extensions by
106 using at least one of the mangled Unicode APIs in the extension.
107
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000108- Two new flags METH_NOARGS and METH_O are available in method definition
109 tables to simplify implementation of methods with no arguments and a
110 single untyped argument. Calling such methods is more efficient than
111 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
112 deprecated.
113
Tim Petersc1731372001-08-04 08:12:36 +0000114Windows
115
116- "import module" now compiles module.pyw if it exists and nothing else
117 relevant is found.
118
Tim Peters20f51a72001-07-21 02:31:40 +0000119
Guido van Rossum55a78992001-07-17 17:22:32 +0000120What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000121===========================
122
123Core
Tim Petersa814db52001-05-14 07:05:58 +0000124
Tim Peters6d6c1a32001-08-02 04:15:00 +0000125- TENTATIVELY, a large amount of code implementing much of what's
126 described in PEP 252 (Making Types Look More Like Classes) and PEP
127 253 (Subtyping Built-in Types) was added. This will be released
128 with Python 2.2a1. Documentation will be provided separately
129 through http://www.python.org/2.2/. The purpose of releasing this
130 with Python 2.2a1 is to test backwards compatibility. It is
131 possible, though not likely, that a decision is made not to release
132 this code as part of 2.2 final, if any serious backwards
133 incompapatibilities are found during alpha testing that cannot be
134 repaired.
135
Guido van Rossum55a78992001-07-17 17:22:32 +0000136- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000137 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000138 more 'yield' statements. See PEP 255. Since this adds a new
139 keyword to the language, this feature must be enabled by including a
140 future statement: "from __future__ import generators" (see PEP 236).
141 Generators will become a standard feature in a future release
142 (probably 2.3). Without this future statement, 'yield' remains an
143 ordinary identifier, but a warning is issued each time it is used.
144 (These warnings currently don't conform to the warnings framework of
145 PEP 230; we intend to fix this in 2.2a2.)
146
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000147- The UTF-16 codec was modified to be more RFC compliant. It will now
148 only remove BOM characters at the start of the string and then
149 only if running in native mode (UTF-16-LE and -BE won't remove a
150 leading BMO character).
151
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000152- Strings now have a new method .decode() to complement the already
153 existing .encode() method. These two methods provide direct access
154 to the corresponding decoders and encoders of the registered codecs.
155
156 To enhance the usability of the .encode() method, the special
157 casing of Unicode object return values was dropped (Unicode objects
158 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000159
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000160 Both methods will now return whatever the codec in charge of the
161 requested encoding returns as object, e.g. Unicode codecs will
162 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
163 will return u"äöü"). This enables codec writer to create codecs
164 for various simple to use conversions.
165
166 New codecs were added to demonstrate these new features (the .encode()
167 and .decode() columns indicate the type of the returned objects):
168
169 Name | .encode() | .decode() | Description
170 ----------------------------------------------------------------------
171 uu | string | string | UU codec (e.g. for email)
172 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000173 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000174 zlib | string | string | zlib compression
175 hex | string | string | 2-byte hex codec
176 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
177
Mark Hammond2a0af792001-05-14 03:09:36 +0000178- Some operating systems now support the concept of a default Unicode
179 encoding for file system operations. Notably, Windows supports 'mbcs'
180 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000181 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000182 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000183
184 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000185 functions that return filenames (such as os.listdir()) to return Python
186 string objects pre-encoded using the default file system encoding for
187 the platform. As this encoding is likely to be different from Python's
188 default encoding, converting this name to a Unicode object before passing
189 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000190 would attempt to use its default encoding (generally ASCII) rather than
191 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000192
Tim Petersa814db52001-05-14 07:05:58 +0000193 In general, this change simply removes surprises when working with
194 Unicode and the file system, making these operations work as you expect,
195 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000196 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000197
Tim Peters61dff2b2001-05-08 15:43:37 +0000198- Float (and complex) literals in source code were evaluated to full
199 precision only when running from a .py file; the same code loaded from a
200 .pyc (or .pyo) file could suffer numeric differences starting at about the
201 12th significant decimal digit. For example, on a machine with IEEE-754
202 floating arithmetic,
203
204 x = 9007199254740992.0
205 print long(x)
206
207 printed 9007199254740992 if run directly from .py, but 9007199254740000
208 if from a compiled (.pyc or .pyo) file. This was due to marshal using
209 str(float) instead of repr(float) when building code objects. marshal
210 now uses repr(float) instead, which should reproduce floats to full
211 machine precision (assuming the platform C float<->string I/O conversion
212 functions are of good quality).
213
214 This may cause floating-point results to change in some cases, and
215 usually for the better, but may also cause numerically unstable
216 algorithms to break.
217
Tim Peters2f228e72001-05-13 00:19:31 +0000218- The implementation of dicts suffers fewer collisions, which has speed
219 benefits. However, the order in which dict entries appear in dict.keys(),
220 dict.values() and dict.items() may differ from previous releases for a
221 given dict. Nothing is defined about this order, so no program should
222 rely on it. Nevertheless, it's easy to write test cases that rely on the
223 order by accident, typically because of printing the str() or repr() of a
224 dict to an "expected results" file. See Lib/test/test_support.py's new
225 sortdict(dict) function for a simple way to display a dict in sorted
226 order.
227
Tim Peters7a3bfc32001-06-12 01:22:22 +0000228- Many other small changes to dicts were made, resulting in faster
229 operation along the most common code paths.
230
Guido van Rossum10315822001-05-01 20:54:30 +0000231- Dictionary objects now support the "in" operator: "x in dict" means
232 the same as dict.has_key(x).
233
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000234- The update() method of dictionaries now accepts generic mapping
235 objects. Specifically the argument object must support the .keys()
236 and __getitem__() methods. This allows you to say, for example,
237 {}.update(UserDict())
238
Guido van Rossum10315822001-05-01 20:54:30 +0000239- Iterators were added; this is a generalized way of providing values
240 to a for loop. See PEP 234. There's a new built-in function iter()
241 to return an iterator. There's a new protocol to get the next value
242 from an iterator using the next() method (in Python) or the
243 tp_iternext slot (in C). There's a new protocol to get iterators
244 using the __iter__() method (in Python) or the tp_iter slot (in C).
245 Iterating (i.e. a for loop) over a dictionary generates its keys.
246 Iterating over a file generates its lines.
247
Tim Petersf553f892001-05-01 20:45:31 +0000248- The following functions were generalized to work nicely with iterator
249 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000250 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000251 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
252 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000253 join() method of strings
254 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000255 'x in y' and 'x not in y' (PySequence_Contains() in C API)
256 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000257 right-hand side of assignment statements with multiple targets, such as
258 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000259
Tim Petersd85e1022001-05-11 21:51:48 +0000260- Accessing module attributes is significantly faster (for example,
261 random.random or os.path or yourPythonModule.yourAttribute).
262
Tim Peterse63415e2001-05-08 04:38:29 +0000263- Comparing dictionary objects via == and != is faster, and now works even
264 if the keys and values don't support comparisons other than ==.
265
Tim Peters95bf9392001-05-10 08:32:44 +0000266- Comparing dictionaries in ways other than == and != is slower: there were
267 insecurities in the dict comparison implementation that could cause Python
268 to crash if the element comparison routines for the dict keys and/or
269 values mutated the dicts. Making the code bulletproof slowed it down.
270
Tim Peterseb28ef22001-06-02 05:27:19 +0000271- Collisions in dicts are resolved via a new approach, which can help
272 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000273 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000274 faster now. Thanks to Christian Tismer for pointing out the cause and
275 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000276
Tim Peters52e155e2001-06-16 05:42:57 +0000277- repr() is much faster for large containers (dict, list, tuple).
278
279
Tim Petersa814db52001-05-14 07:05:58 +0000280Library
281
Fred Drake960fdf92001-07-20 18:38:26 +0000282- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
283 were added to the string module. These a locale-indenpendent
284 constants, unlike letters, lowercase, and uppercase. These are now
285 use in appropriate locations in the standard library.
286
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000287- The flags used in dlopen calls can now be configured using
288 sys.setdlopenflags and queried using sys.getdlopenflags.
289
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000290- Fredrik Lundh's xmlrpclib is now a standard library module. This
291 provides full client-side XML-RPC support. In addition,
292 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
293 one asyncore-based). Thanks to Eric Raymond for the documentation.
294
Guido van Rossum643d3912001-07-05 14:46:25 +0000295- The xrange() object is simplified: it no longer supports slicing,
296 repetition, comparisons, efficient 'in' checking, the tolist()
297 method, or the start, stop and step attributes. See PEP 260.
298
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000299- A new function fnmatch.filter to filter lists of file names was added.
300
Barry Warsawffd674d2001-05-22 16:00:10 +0000301- calendar.py uses month and day names based on the current locale.
302
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000303- strop is now *really* obsolete (this was announced before with 1.6),
304 and issues DeprecationWarning when used (except for the four items
305 that are still imported into string.py).
306
Tim Petersa814db52001-05-14 07:05:58 +0000307- Cookie.py now sorts key+value pairs by key in output strings.
308
309- pprint.isrecursive(object) didn't correctly identify recursive objects.
310 Now it does.
311
Tim Peters95b3f782001-05-14 18:39:41 +0000312- pprint functions now much faster for large containers (tuple, list, dict).
313
Tim Peters7b9542a2001-06-10 23:40:19 +0000314- New 'q' and 'Q' format codes in the struct module, corresponding to C
315 types "long long" and "unsigned long long" (on Windows, __int64). In
316 native mode, these can be used only when the platform C compiler supports
317 these types (when HAVE_LONG_LONG is #define'd by the Python config
318 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000319 In standard mode, 'q' and 'Q' are supported on all platforms, and are
320 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000321
Guido van Rossum83213cc2001-06-12 16:48:52 +0000322- The site module installs a new built-in function 'help' that invokes
323 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
324 it displays a message reminding the user to use 'help()' or
325 'help(object)'.
326
Tim Petersa814db52001-05-14 07:05:58 +0000327Tests
328
329- New test_mutants.py runs dict comparisons where the key and value
330 comparison operators mutute the dicts randomly during comparison. This
331 rapidly causes Python to crash under earlier releases (not for the faint
332 of heart: it can also cause Win9x to freeze or reboot!).
333
334- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000335 pprint.isreadable() return sensible results. Also verifies that simple
336 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000337
Tim Peters58e0a8c2001-05-14 22:32:33 +0000338New platforms
339
340- Python should compile and run out of the box using the Borland C
341 compiler (under Windows), thanks to Stephen Hansen.
Tim Petersf553f892001-05-01 20:45:31 +0000342
Tim Peters4324aa32001-05-28 22:30:08 +0000343C API
344
345- Removed the unused last_is_sticky argument from the internal
346 _PyTuple_Resize(). If this affects you, you were cheating.
347
348
Guido van Rossum55a78992001-07-17 17:22:32 +0000349======================================================================
350
351
Guido van Rossumffe13be2001-04-16 18:46:45 +0000352What's New in Python 2.1 (final)?
353=================================
354
355We only changed a few things since the last release candidate, all in
356Python library code:
357
358- A bug in the locale module was fixed that affected locales which
359 define no grouping for numeric formatting.
360
361- A few bugs in the weakref module's implementations of weak
362 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
363 and the test suite was updated to check for these bugs.
364
365- An old bug in the os.path.walk() function (introduced in Python
366 2.0!) was fixed: a non-existent file would cause an exception
367 instead of being ignored.
368
369- Fixed a few bugs in the new symtable module found by Neil Norwitz's
370 PyChecker.
371
372
Guido van Rossum5b08f132001-04-16 02:05:23 +0000373What's New in Python 2.1c2?
374===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000375
Guido van Rossum5b08f132001-04-16 02:05:23 +0000376A flurry of small changes, and one showstopper fixed in the nick of
377time made it necessary to release another release candidate. The list
378here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000379
Guido van Rossum5b08f132001-04-16 02:05:23 +0000380Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000381
Guido van Rossum5b08f132001-04-16 02:05:23 +0000382- Tim discovered a nasty bug in the dictionary code, caused by
383 PyDict_Next() calling dict_resize(), and the GC code's use of
384 PyDict_Next() violating an assumption in dict_items(). This was
385 fixed with considerable amounts of band-aid, but the net effect is a
386 saner and more robust implementation.
387
388- Made a bunch of symbols static that were accidentally global.
389
390Build and Ports
391
392- The setup.py script didn't check for a new enough version of zlib
393 (1.1.3 is needed). Now it does.
394
395- Changed "make clean" target to also remove shared libraries.
396
397- Added a more general warning about the SGI Irix optimizer to README.
398
399Library
400
401- Fix a bug in urllib.basejoin("http://host", "../file.html") which
402 omitted the slash between host and file.html.
403
404- The mailbox module's _Mailbox class contained a completely broken
405 and undocumented seek() method. Ripped it out.
406
407- Fixed a bunch of typos in various library modules (urllib2, smtpd,
408 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
409
410- Fixed a few last-minute bugs in unittest.
411
412Extensions
413
414- Reverted the patch to the OpenSSL code in socketmodule.c to support
415 RAND_status() and the EGD, and the subsequent patch that tried to
416 fix it for pre-0.9.5 versions; the problem with the patch is that on
417 some systems it issues a warning whenever socket is imported, and
418 that's unacceptable.
419
420Tests
421
422- Fixed the pickle tests to work with "import test.test_pickle".
423
424- Tweaked test_locale.py to actually run the test Windows.
425
426- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
427 not "wb" (which is not a valid mode at all).
428
429- Fix pstats browser crashes. Import readline if it exists to make
430 the user interface nicer.
431
432- Add "import thread" to the top of test modules that import the
433 threading module (test_asynchat and test_threadedtempfile). This
434 prevents test failures caused by a broken threading module resulting
435 from a previously caught failed import.
436
437- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
438 needed on some platforms (e.g. Solaris 8) when the tests are run
439 twice in succession.
440
441- Skip rather than fail test_sunaudiodev if no audio device is found.
442
443
444What's New in Python 2.1c1?
445===========================
446
447This list was significantly updated when 2.1c2 was released; the 2.1c1
448release didn't mention most changes that were actually part of 2.1c1:
449
450Legal
451
452- Copyright was assigned to the Python Software Foundation (PSF) and a
453 PSF license (very similar to the CNRI license) was added.
454
455- The CNRI copyright notice was updated to include 2001.
456
457Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000458
Guido van Rossumc9932722001-04-12 02:31:27 +0000459- After a public outcry, assignment to __debug__ is no longer illegal;
460 instead, a warning is issued. It will become illegal in 2.2.
461
Guido van Rossum5b08f132001-04-16 02:05:23 +0000462- Fixed a core dump with "%#x" % 0, and changed the semantics so that
463 "%#x" now always prepends "0x", even if the value is zero.
464
465- Fixed some nits in the bytecode compiler.
466
467- Fixed core dumps when calling certain kinds of non-functions.
468
469- Fixed various core dumps caused by reference count bugs.
470
471Build and Ports
472
473- Use INSTALL_SCRIPT to install script files.
474
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000475- New port: SCO Unixware 7, by Billy G. Allie.
476
Guido van Rossum5b08f132001-04-16 02:05:23 +0000477- Updated RISCOS port.
478
479- Updated BeOS port and notes.
480
481- Various other porting problems resolved.
482
483Library
484
485- The TERMIOS and SOCKET modules are now truly obsolete and
486 unnecessary. Their symbols are incorporated in the termios and
487 socket modules.
488
489- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
490 better tests for pickling.
491
492- threading: make Condition.wait() robust against KeyboardInterrupt.
493
494- zipfile: add support to zipfile to support opening an archive
495 represented by an open file rather than a file name. Fix bug where
496 the archive was not properly closed. Fixed a bug in this bugfix
497 where flush() was called for a read-only file.
498
499- imputil: added an uninstall() method to the ImportManager.
500
501- Canvas: fixed bugs in lower() and tkraise() methods.
502
503- SocketServer: API change (added overridable close_request() method)
504 so that the TCP server can explicitly close the request.
505
506- pstats: Eric Raymond added a simple interactive statistics browser,
507 invoked when the module is run as a script.
508
509- locale: fixed a problem in format().
510
511- webbrowser: made it work when the BROWSER environment variable has a
512 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
513 KDE 2. Fixed some other nits.
514
515- unittest: changes to allow using a different exception than
516 AssertionError, and added a few more function aliases. Some other
517 small changes.
518
519- urllib, urllib2: fixed redirect problems and a coupleof other nits.
520
521- asynchat: fixed a critical bug in asynchat that slipped through the
522 2.1b2 release. Fixed another rare bug.
523
524- Fix some unqualified except: clauses (always a bad code example).
525
526XML
527
528- pyexpat: new API get_version_string().
529
530- Fixed some minidom bugs.
531
532Extensions
533
534- Fixed a core dump in _weakref. Removed the weakref.mapping()
535 function (it adds nothing to the API).
536
537- Rationalized the use of header files in the readline module, to make
538 it compile (albeit with some warnings) with the very recent readline
539 4.2, without breaking for earlier versions.
540
541- Hopefully fixed a buffering problem in linuxaudiodev.
542
543- Attempted a fix to make the OpenSSL support in the socket module
544 work again with pre-0.9.5 versions of OpenSSL.
545
546Tests
547
548- Added a test case for asynchat and asyncore.
549
550- Removed coupling between tests where one test failing could break
551 another.
552
553Tools
554
555- Ping added an interactive help browser to pydoc, fixed some nits
556 in the rest of the pydoc code, and added some features to his
557 inspect module.
558
559- An updated python-mode.el version 4.1 which integrates Ken
560 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
561 much nicer in XEmacs and Emacs. When stepping through your program
562 with pdb, in either the shell window or the *Python* window, the
563 source file and line will be tracked by an arrow. Very cool!
564
565- IDLE: syntax warnings in interactive mode are changed into errors.
566
567- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +0000568 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +0000569
570- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000571
Barry Warsaw11e89c72001-04-11 20:37:57 +0000572
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000573What's New in Python 2.1 beta 2?
574================================
575
Guido van Rossum053ae352001-03-22 14:17:21 +0000576(Unlisted are many fixed bugs, more documentation, etc.)
577
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000578Core language, builtins, and interpreter
579
Guido van Rossum053ae352001-03-22 14:17:21 +0000580- The nested scopes work (enabled by "from __future__ import
581 nested_scopes") is completed; in particular, the future now extends
582 into code executed through exec, eval() and execfile(), and into the
583 interactive interpreter.
584
585- When calling a base class method (e.g. BaseClass.__init__(self)),
586 this is now allowed even if self is not strictly spoken a class
587 instance (e.g. when using metaclasses or the Don Beaudry hook).
588
589- Slice objects are now comparable but not hashable; this prevents
590 dict[:] from being accepted but meaningless.
591
592- Complex division is now calculated using less braindead algorithms.
593 This doesn't change semantics except it's more likely to give useful
594 results in extreme cases. Complex repr() now uses full precision
595 like float repr().
596
597- sgmllib.py now calls handle_decl() for simple <!...> declarations.
598
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000599- It is illegal to assign to the name __debug__, which is set when the
600 interpreter starts. It is effectively a compile-time constant.
601
602- A warning will be issued if a global statement for a variable
603 follows a use or assignment of that variable.
604
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000605Standard library
606
Guido van Rossum053ae352001-03-22 14:17:21 +0000607- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
608 inspired by JUnit), is now part of the standard library. You now
609 have a choice of two testing frameworks: unittest requires you to
610 write testcases as separate code, doctest gathers them from
611 docstrings. Both approaches have their advantages and
612 disadvantages.
613
614- A new module Tix was added, which wraps the Tix extension library
615 for Tk. With that module, it is not necessary to statically link
616 Tix with _tkinter, since Tix will be loaded with Tcl's "package
617 require" command. See Demo/tix/.
618
619- tzparse.py is now obsolete.
620
621- In gzip.py, the seek() and tell() methods are removed -- they were
622 non-functional anyway, and it's better if callers can test for their
623 existence with hasattr().
624
625Python/C API
626
627- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
628 that's already in the dictionary during a PyDict_Next() iteration.
629 This used to fail occasionally when a dictionary resize operation
630 could be triggered that would rehash all the keys. All other
631 modifications to the dictionary are still off-limits during a
632 PyDict_Next() iteration!
633
634- New extended APIs related to passing compiler variables around.
635
636- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
637 implement isinstance() and issubclass().
638
639- Py_BuildValue() now has a "D" conversion to create a Python complex
640 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000641
Fred Drake4e262a92001-03-22 18:26:47 +0000642- Extensions types which support weak references must now set the
643 field allocated for the weak reference machinery to NULL themselves;
644 this is done to avoid the cost of checking each object for having a
645 weakly referencable type in PyObject_INIT(), since most types are
646 not weakly referencable.
647
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000648- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
649 free variables and cell variables to and from the frame's f_locals.
650
651- Variants of several functions defined in pythonrun.h have been added
652 to support the nested_scopes future statement. The variants all end
653 in Flags and take an extra argument, a PyCompilerFlags *; examples:
654 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
655 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +0000656 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000657
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000658Distutils
659
660- the sdist command now writes a PKG-INFO file, as described in PEP 241,
661 into the release tree.
662
Tim Peters0e57abf2001-05-02 07:39:38 +0000663- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000664 (an uninstaller, more customization of the installer's display)
665
666- from Jack Jansen: added Mac-specific code to generate a dialog for
667 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +0000668 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000669 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +0000670
671- added 'platforms' and 'keywords' to the set of metadata that can be
672 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000673
674- applied patches from Jason Tishler to make the compiler class work with
675 Cygwin.
676
677
Tim Peters2fe289a2001-03-01 22:19:38 +0000678What's New in Python 2.1 beta 1?
679================================
Tim Petersd66595f2001-02-04 03:09:53 +0000680
681Core language, builtins, and interpreter
682
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000683- Following an outcry from the community about the amount of code
684 broken by the nested scopes feature introduced in 2.1a2, we decided
685 to make this feature optional, and to wait until Python 2.2 (or at
686 least 6 months) to make it standard. The option can be enabled on a
687 per-module basis by adding "from __future__ import nested_scopes" at
688 the beginning of a module (before any other statements, but after
689 comments and an optional docstring). See PEP 236 (Back to the
690 __future__) for a description of the __future__ statement. PEP 227
691 (Statically Nested Scopes) has been updated to reflect this change,
692 and to clarify the semantics in a number of endcases.
693
694- The nested scopes code, when enabled, has been hardened, and most
695 bugs and memory leaks in it have been fixed.
696
697- Compile-time warnings are now generated for a number of conditions
698 that will break or change in meaning when nested scopes are enabled:
699
700 - Using "from...import *" or "exec" without in-clause in a function
701 scope that also defines a lambda or nested function with one or
702 more free (non-local) variables. The presence of the import* or
703 bare exec makes it impossible for the compiler to determine the
704 exact set of local variables in the outer scope, which makes it
705 impossible to determine the bindings for free variables in the
706 inner scope. To avoid the warning about import *, change it into
707 an import of explicitly name object, or move the import* statement
708 to the global scope; to avoid the warning about bare exec, use
709 exec...in... (a good idea anyway -- there's a possibility that
710 bare exec will be deprecated in the future).
711
712 - Use of a global variable in a nested scope with the same name as a
713 local variable in a surrounding scope. This will change in
714 meaning with nested scopes: the name in the inner scope will
715 reference the variable in the outer scope rather than the global
716 of the same name. To avoid the warning, either rename the outer
717 variable, or use a global statement in the inner function.
718
Neil Schemenauera35c6882001-02-27 04:45:05 +0000719- An optional object allocator has been included. This allocator is
720 optimized for Python objects and should be faster and use less memory
721 than the standard system allocator. It is not enabled by default
722 because of possible thread safety problems. The allocator is only
723 protected by the Python interpreter lock and it is possible that some
724 extension modules require a thread safe allocator. The object
725 allocator can be enabled by providing the "--with-pymalloc" option to
726 configure.
727
Tim Petersd66595f2001-02-04 03:09:53 +0000728Standard library
729
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000730- pyexpat now detects the expat version if expat.h defines it. A
731 number of additional handlers are provided, which are only available
732 since expat 1.95. In addition, the methods SetParamEntityParsing and
733 GetInputContext of Parser objects are available with 1.95.x
734 only. Parser objects now provide the ordered_attributes and
735 specified_attributes attributes. A new module expat.model was added,
736 which offers a number of additional constants if 1.95.x is used.
737
738- xml.dom offers the new functions registerDOMImplementation and
739 getDOMImplementation.
740
741- xml.dom.minidom offers a toprettyxml method. A number of DOM
742 conformance issues have been resolved. In particular, Element now
743 has an hasAttributes method, and the handling of namespaces was
744 improved.
745
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000746- Ka-Ping Yee contributed two new modules: inspect.py, a module for
747 getting information about live Python code, and pydoc.py, a module
748 for interactively converting docstrings to HTML or text.
749 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000750 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000751 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
752 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000753
Tim Peters1eff7962001-03-01 02:31:33 +0000754- New library module difflib.py, primarily packaging the SequenceMatcher
755 class at the heart of the popular ndiff.py file-comparison tool.
756
757- doctest.py (a framework for verifying Python code examples in docstrings)
758 is now part of the std library.
759
Tim Petersd66595f2001-02-04 03:09:53 +0000760Windows changes
761
Guido van Rossume3955a82001-03-02 14:05:59 +0000762- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
763 small GUI that lets you browse the module docstrings using your
764 default web browser.
765
Tim Peters1eff7962001-03-01 02:31:33 +0000766- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
767 Platforms) is implemented. See
768
769 http://python.sourceforge.net/peps/pep-0235.html
770
771 for full details, especially the "Current Lower-Left Semantics" section.
772 The new Windows import rules are simpler than before:
773
774 A. If the PYTHONCASEOK environment variable exists, same as
775 before: silently accept the first case-insensitive match of any
776 kind; raise ImportError if none found.
777
778 B. Else search sys.path for the first case-sensitive match; raise
779 ImportError if none found.
780
781 The same rules have been implented on other platforms with case-
782 insensitive but case-preserving filesystems too (including Cygwin, and
783 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000784
Tim Peters25a9ce32001-02-19 07:06:36 +0000785- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
786 what it's supposed to do (and does do under NT and 2000) via direct
787 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000788 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000789 all Win9x systems before.
790
Tim Peters1eff7962001-03-01 02:31:33 +0000791- Build: Subproject _test (effectively) renamed to _testcapi.
792
Tim Peters2fe289a2001-03-01 22:19:38 +0000793New platforms
794
795- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
796 Thanks to Steven Majewski!
797
798- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
799 Tishler!
800
Guido van Rossum9089b272001-03-02 06:49:50 +0000801- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
802 Schwertberger! See RISCOS/README for more information -- it seems
803 that because of the bizarre filename conventions on RISCOS, no port
804 to that platform is easy. Note that the new variable os.endsep is
805 silently supported in order to make life easier on this platform,
806 but we don't advertise it because it's not worth for most folks to
807 care about RISCOS portability.
808
Tim Peters25a9ce32001-02-19 07:06:36 +0000809
Tim Petersd7b5e882001-01-25 03:36:26 +0000810What's New in Python 2.1 alpha 2?
811=================================
Tim Peters40ead762001-01-27 05:35:26 +0000812
Tim Petersd7b5e882001-01-25 03:36:26 +0000813Core language, builtins, and interpreter
814
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000815- Scopes nest. If a name is used in a function or class, but is not
816 local, the definition in the nearest enclosing function scope will
817 be used. One consequence of this change is that lambda statements
818 could reference variables in the namespaces where the lambda is
819 defined. In some unusual cases, this change will break code.
820
821 In all previous version of Python, names were resolved in exactly
822 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000823 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000824 function A is defined within a function B, the names bound in B are
825 not visible in A. The new rules make names bound in B visible in A,
826 unless A contains a name binding that hides the binding in B.
827
828 Section 4.1 of the reference manual describes the new scoping rules
829 in detail. The test script in Lib/test/test_scope.py demonstrates
830 some of the effects of the change.
831
832 The new rules will cause existing code to break if it defines nested
833 functions where an outer function has local variables with the same
834 name as globals or builtins used by the inner function. Example:
835
836 def munge(str):
837 def helper(x):
838 return str(x)
839 if type(str) != type(''):
840 str = helper(str)
841 return str.strip()
842
843 Under the old rules, the name str in helper() is bound to the
844 builtin function str(). Under the new rules, it will be bound to
845 the argument named str and an error will occur when helper() is
846 called.
847
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000848- The compiler will report a SyntaxError if "from ... import *" occurs
849 in a function or class scope. The language reference has documented
850 that this case is illegal, but the compiler never checked for it.
851 The recent introduction of nested scope makes the meaning of this
852 form of name binding ambiguous. In a future release, the compiler
853 may allow this form when there is no possibility of ambiguity.
854
Tim Peters40ead762001-01-27 05:35:26 +0000855- repr(string) is easier to read, now using hex escapes instead of octal,
856 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
857
858 >>> "\texample \r\n" + chr(0) + chr(255)
859 '\texample \r\n\x00\xff' # in 2.1
860 '\011example \015\012\000\377' # in 2.0
861
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000862- Functions are now compared and hashed by identity, not by value, since
863 the func_code attribute is writable.
864
Fred Drakefb9d7122001-02-01 20:00:40 +0000865- Weak references (PEP 205) have been added. This involves a few
866 changes in the core, an extension module (_weakref), and a Python
867 module (weakref). The weakref module is the public interface. It
868 includes support for "explicit" weak references, proxy objects, and
869 mappings with weakly held values.
870
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000871- A 'continue' statement can now appear in a try block within the body
872 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000873 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000874
Tim Petersd7b5e882001-01-25 03:36:26 +0000875Standard library
876
Barry Warsaw30dbd142001-01-31 22:14:01 +0000877- mailbox.py now has a new class, PortableUnixMailbox which is
878 identical to UnixMailbox but uses a more portable scheme for
879 determining From_ separators. Also, the constructors for all the
880 classes in this module have a new optional `factory' argument, which
881 is a callable used when new message classes must be instantiated by
882 the next() method.
883
Tim Petersd7b5e882001-01-25 03:36:26 +0000884- random.py is now self-contained, and offers all the functionality of
885 the now-deprecated whrandom.py. See the docs for details. random.py
886 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000887 and restoring the internal state of the generator; and jumpahead(n),
888 for quickly forcing the internal state to be the same as if n calls to
889 random() had been made. The latter is particularly useful for multi-
890 threaded programs, creating one instance of the random.Random() class for
891 each thread, then using .jumpahead() to force each instance to use a
892 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000893
Tim Peters0de88fc2001-02-01 04:59:18 +0000894- random.py's seed() function is new. For bit-for-bit compatibility with
895 prior releases, use the whseed function instead. The new seed function
896 addresses two problems: (1) The old function couldn't produce more than
897 about 2**24 distinct internal states; the new one about 2**45 (the best
898 that can be done in the Wichmann-Hill generator). (2) The old function
899 sometimes produced identical internal states when passed distinct
900 integers, and there was no simple way to predict when that would happen;
901 the new one guarantees to produce distinct internal states for all
902 arguments in [0, 27814431486576L).
903
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000904- The socket module now supports raw packets on Linux. The socket
905 family is AF_PACKET.
906
Tim Peters9ea17ac2001-02-02 05:57:15 +0000907- test_capi.py is a start at running tests of the Python C API. The tests
908 are implemented by the new Modules/_testmodule.c.
909
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000910- A new extension module, _symtable, provides provisional access to the
911 internal symbol table used by the Python compiler. A higher-level
912 interface will be added on top of _symtable in a future release.
913
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000914- Removed the obsolete soundex module.
915
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000916- xml.dom.minidom now uses the standard DOM exceptions. Node supports
917 the isSameNode method; NamedNodeMap the get method.
918
919- xml.sax.expatreader supports the lexical handler property; it
920 generates comment, startCDATA, and endCDATA events.
921
Tim Petersee826f82001-01-31 19:39:44 +0000922Windows changes
923
924- Build procedure: the zlib project is built in a different way that
925 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000926 the zlib binary used. See PCbuild\readme.txt for details. Your old
927 zlib-related directories can be deleted; you'll need to download fresh
928 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000929
Tim Peters9ea17ac2001-02-02 05:57:15 +0000930- Build: New subproject _test for the benefit of test_capi.py (see above).
931
Tim Petersb16c56f2001-02-02 21:24:51 +0000932- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
933 interface to some Python compiler internals).
934
935- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000936 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000937
Tim Petersa3a3a032000-11-30 05:22:44 +0000938What's New in Python 2.1 alpha 1?
939=================================
940
941Core language, builtins, and interpreter
942
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000943- There is a new Unicode companion to the PyObject_Str() API
944 called PyObject_Unicode(). It behaves in the same way as the
945 former, but assures that the returned value is an Unicode object
946 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000947
Guido van Rossumf98eda02001-01-17 15:54:45 +0000948- The comparison operators support "rich comparison overloading" (PEP
949 207). C extension types can provide a rich comparison function in
950 the new tp_richcompare slot in the type object. The cmp() function
951 and the C function PyObject_Compare() first try the new rich
952 comparison operators before trying the old 3-way comparison. There
953 is also a new C API PyObject_RichCompare() (which also falls back on
954 the old 3-way comparison, but does not constrain the outcome of the
955 rich comparison to a Boolean result).
956
957 The rich comparison function takes two objects (at least one of
958 which is guaranteed to have the type that provided the function) and
959 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
960 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
961 object, which may be NotImplemented (in which case the tp_compare
962 slot function is used as a fallback, if defined).
963
964 Classes can overload individual comparison operators by defining one
965 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000966 __ge__. There are no explicit "reflected argument" versions of
967 these; instead, __lt__ and __gt__ are each other's reflection,
968 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
969 reflection (similar at the C level). No other implications are
970 made; in particular, Python does not assume that == is the Boolean
971 inverse of !=, or that < is the Boolean inverse of >=. This makes
972 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000973
974 Classes or types that want to implement (in)equality tests but not
975 the ordering operators (i.e. unordered types) should implement ==
976 and !=, and raise an error for the ordering operators.
977
Guido van Rossuma88479f2001-01-18 14:28:08 +0000978 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +0000979 Boolean; e.g. a matrix type might want to return a matrix of bits
980 for A < B, giving elementwise comparisons. Such types should ensure
981 that any interpretation of their value in a Boolean context raises
982 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
983 at the C level) to always raise an exception.
984
Guido van Rossuma88479f2001-01-18 14:28:08 +0000985- Complex numbers use rich comparisons to define == and != but raise
986 an exception for <, <=, > and >=. Unfortunately, this also means
987 that cmp() of two complex numbers raises an exception when the two
988 numbers differ. Since it is not mathematically meaningful to compare
989 complex numbers except for equality, I hope that this doesn't break
990 too much code.
991
Tim Peters3389f192001-02-18 08:48:49 +0000992- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +0000993 not defined by the language, other than that it's arbitrary but
994 consistent (see the Reference Manual). An implementation detail changed
995 in 2.1a1 such that None now compares less than any other object. Code
996 relying on this new behavior (like code that relied on the previous
997 behavior) does so at its own risk.
998
Barry Warsaw573b5412001-01-15 20:43:18 +0000999- Functions and methods now support getting and setting arbitrarily
1000 named attributes (PEP 232). Functions have a new __dict__
1001 (a.k.a. func_dict) which hold the function attributes. Methods get
1002 and set attributes on their underlying im_func. It is a TypeError
1003 to set an attribute on a bound method.
1004
Guido van Rossum051e3352001-01-15 19:11:10 +00001005- The xrange() object implementation has been improved so that
1006 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1007 limitation that in this case len(xrange(sys.maxint)) can't be
1008 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1009 work fine as long as the index i doesn't actually reach 2**31.
1010 (Python uses regular ints for sequence and string indices; fixing
1011 that is much more work.)
1012
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001013- Two changes to from...import:
1014
Guido van Rossumba381232001-02-03 15:06:40 +00001015 1) "from M import X" now works even if (after loading module M)
1016 sys.modules['M'] is not a real module; it's basically a getattr()
1017 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001018
1019 2) "from M import *" now looks for M.__all__ to decide which names to
1020 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1021 filters out names starting with '_' as before. Whether or not
1022 __all__ exists, there's no restriction on the type of M.
1023
Guido van Rossumf61f1662001-01-10 20:13:55 +00001024- File objects have a new method, xreadlines(). This is the fastest
1025 way to iterate over all lines in a file:
1026
1027 for line in file.xreadlines():
1028 ...do something to line...
1029
1030 See the xreadlines module (mentioned below) for how to do this for
1031 other file-like objects.
1032
1033- Even if you don't use file.xreadlines(), you may expect a speedup on
1034 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001035 quite a bit in platform-specific ways: on systems (like Linux) that
1036 support flockfile(), getc_unlocked(), and funlockfile(), those are
1037 used by default. On systems (like Windows) without getc_unlocked(),
1038 a complicated (but still thread-safe) method using fgets() is used by
1039 default.
1040
Tim Petersd52269b2001-01-25 06:23:18 +00001041 You can force use of the fgets() method by #define'ing
1042 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001043 getc_unlocked()).
1044
Tim Petersd52269b2001-01-25 06:23:18 +00001045 You can force fgets() not to be used by #define'ing
1046 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001047 test_bufio.py fails -- and let us know if it does!).
1048
1049- In addition, the fileinput module, while still slower than the other
1050 methods on most platforms, has been sped up too, by using
1051 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001052
1053- Support for run-time warnings has been added, including a new
1054 command line option (-W) to specify the disposition of warnings.
1055 See the description of the warnings module below.
1056
1057- Extensive changes have been made to the coercion code. This mostly
1058 affects extension modules (which can now implement mixed-type
1059 numerical operators without having to use coercion), but
1060 occasionally, in boundary cases the coercion semantics have changed
1061 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001062 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001063 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001064 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001065
Guido van Rossumf98eda02001-01-17 15:54:45 +00001066- In connection with the coercion changes, a new built-in singleton
1067 object, NotImplemented is defined. This can be returned for
1068 operations that wish to indicate they are not implemented for a
1069 particular combination of arguments. From C, this is
1070 Py_NotImplemented.
1071
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001072- The interpreter accepts now bytecode files on the command line even
1073 if they do not have a .pyc or .pyo extension. On Linux, after executing
1074
Martin v. Löwise214baa2001-02-04 22:37:56 +00001075import imp,sys,string
1076magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1077reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1078open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001079
1080 any byte code file can be used as an executable (i.e. as an argument
1081 to execve(2)).
1082
Tim Peters9940b802000-12-01 07:59:35 +00001083- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001084 character. In 1.6 and earlier, they never produced a sign,
1085 and raised an error if the value of the long was too large
1086 to fit in a Python int. In 2.0, they produced a sign if and
1087 only if too large to fit in an int. This was inconsistent
1088 across platforms (because the size of an int varies across
1089 platforms), and inconsistent with hex() and oct(). Example:
1090
1091 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001092 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001093 'ffffffbe' # in 2.0 and before, on 32-bit machines
1094 >>> hex(-0x42L)
1095 '-0x42L' # in all versions of Python
1096
Tim Peters9940b802000-12-01 07:59:35 +00001097 The behavior of %d formats for negative Python longs remains
1098 the same as in 2.0 (although in 1.6 and before, they raised
1099 an error if the long didn't fit in a Python int).
1100
1101 %u formats don't make sense for Python longs, but are allowed
1102 and treated the same as %d in 2.1. In 2.0, a negative long
1103 formatted via %u produced a sign if and only if too large to
1104 fit in an int. In 1.6 and earlier, a negative long formatted
1105 via %u raised an error if it was too big to fit in an int.
1106
Guido van Rossum3661d392000-12-12 22:10:31 +00001107- Dictionary objects have an odd new method, popitem(). This removes
1108 an arbitrary item from the dictionary and returns it (in the form of
1109 a (key, value) pair). This can be useful for algorithms that use a
1110 dictionary as a bag of "to do" items and repeatedly need to pick one
1111 item. Such algorithms normally end up running in quadratic time;
1112 using popitem() they can usually be made to run in linear time.
1113
Tim Peters36cdad12000-12-29 02:06:45 +00001114Standard library
1115
Thomas Woutersfe385252001-01-19 23:16:56 +00001116- In the time module, the time argument to the functions strftime,
1117 localtime, gmtime, asctime and ctime is now optional, defaulting to
1118 the current time (in the local timezone).
1119
Guido van Rossumda91f222001-01-15 16:36:08 +00001120- The ftplib module now defaults to passive mode, which is deemed a
1121 more useful default given that clients are often inside firewalls
1122 these days. Note that this could break if ftplib is used to connect
1123 to a *server* that is inside a firewall, from outside; this is
1124 expected to be a very rare situation. To fix that, you can call
1125 ftp.set_pasv(0).
1126
Martin v. Löwis10a27872001-01-13 09:54:41 +00001127- The module site now treats .pth files not only for path configuration,
1128 but also supports extensions to the initialization code: Lines starting
1129 with import are executed.
1130
Guido van Rossumf61f1662001-01-10 20:13:55 +00001131- There's a new module, warnings, which implements a mechanism for
1132 issuing and filtering warnings. There are some new built-in
1133 exceptions that serve as warning categories, and a new command line
1134 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1135 turns warnings into errors). warnings.warn(message[, category])
1136 issues a warning message; this can also be called from C as
1137 PyErr_Warn(category, message).
1138
1139- A new module xreadlines was added. This exports a single factory
1140 function, xreadlines(). The intention is that this code is the
1141 absolutely fastest way to iterate over all lines in an open
1142 file(-like) object:
1143
1144 import xreadlines
1145 for line in xreadlines.xreadlines(file):
1146 ...do something to line...
1147
1148 This is equivalent to the previous the speed record holder using
1149 file.readlines(sizehint). Note that if file is a real file object
1150 (as opposed to a file-like object), this is equivalent:
1151
1152 for line in file.xreadlines():
1153 ...do something to line...
1154
Tim Peters36cdad12000-12-29 02:06:45 +00001155- The bisect module has new functions bisect_left, insort_left,
1156 bisect_right and insort_right. The old names bisect and insort
1157 are now aliases for bisect_right and insort_right. XXX_right
1158 and XXX_left methods differ in what happens when the new element
1159 compares equal to one or more elements already in the list: the
1160 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001161 right. Code that doesn't care where equal elements end up should
1162 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001163
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001164- The new curses.panel module wraps the panel library that forms part
1165 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1166
Guido van Rossumf61f1662001-01-10 20:13:55 +00001167- The SocketServer module now sets the allow_reuse_address flag by
1168 default in the TCPServer class.
1169
1170- A new function, sys._getframe(), returns the stack frame pointer of
1171 the caller. This is intended only as a building block for
1172 higher-level mechanisms such as string interpolation.
1173
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001174- The pyexpat module supports a number of new handlers, which are
1175 available only in expat 1.2. If invocation of a callback fails, it
1176 will report an additional frame in the traceback. Parser objects
1177 participate now in garbage collection. If expat reports an unknown
1178 encoding, pyexpat will try to use a Python codec; that works only
1179 for single-byte charsets. The parser type objects is exposed as
1180 XMLParserObject.
1181
1182- xml.dom now offers standard definitions for symbolic node type and
1183 exception code constants, and a hierarchy of DOM exceptions. minidom
1184 was adjusted to use them.
1185
1186- The conformance of xml.dom.minidom to the DOM specification was
1187 improved. It detects a number of additional error cases; the
1188 previous/next relationship works even when the tree is modified;
1189 Node supports the normalize() method; NamedNodeMap, DocumentType and
1190 DOMImplementation classes were added; Element supports the
1191 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1192 method.
1193
Guido van Rossumf61f1662001-01-10 20:13:55 +00001194Build issues
1195
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001196- For Unix (and Unix-compatible) builds, configuration and building of
1197 extension modules is now greatly automated. Rather than having to
1198 edit the Modules/Setup file to indicate which modules should be
1199 built and where their include files and libraries are, a
1200 distutils-based setup.py script now takes care of building most
1201 extension modules. All extension modules built this way are built
1202 as shared libraries. Only a few modules that must be linked
1203 statically are still listed in the Setup file; you won't need to
1204 edit their configuration.
1205
1206- Python should now build out of the box on Cygwin. If it doesn't,
1207 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001208
1209- Python now always uses its own (renamed) implementation of getopt()
1210 -- there's too much variation among C library getopt()
1211 implementations.
1212
1213- C++ compilers are better supported; the CXX macro is always set to a
1214 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001215
Tim Petersd92dfe02000-12-12 01:18:41 +00001216Windows changes
1217
1218- select module: By default under Windows, a select() call
1219 can specify no more than 64 sockets. Python now boosts
1220 this Microsoft default to 512. If you need even more than
1221 that, see the MS docs (you'll need to #define FD_SETSIZE
1222 and recompile Python from source).
1223
Guido van Rossumf61f1662001-01-10 20:13:55 +00001224- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1225 subdirectory is no more!
1226
Tim Petersa3a3a032000-11-30 05:22:44 +00001227
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001228What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001229=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001230
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001231Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001232changes are in the file HISTORY. If you are making the jump directly
1233from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1234HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001235
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001236Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1237the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1238http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001239
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001240--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001241
1242======================================================================
1243
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001244What's new in 2.0 (since release candidate 1)?
1245==============================================
1246
1247Standard library
1248
1249- The copy_reg module was modified to clarify its intended use: to
1250 register pickle support for extension types, not for classes.
1251 pickle() will raise a TypeError if it is passed a class.
1252
1253- Fixed a bug in gettext's "normalize and expand" code that prevented
1254 it from finding an existing .mo file.
1255
1256- Restored support for HTTP/0.9 servers in httplib.
1257
Tim Peters989b7b92000-10-16 20:24:53 +00001258- The math module was changed to stop raising OverflowError in case of
1259 underflow, and return 0 instead in underflow cases. Whether Python
1260 used to raise OverflowError in case of underflow was platform-
1261 dependent (it did when the platform math library set errno to ERANGE
1262 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001263
1264- Fixed a bug in StringIO that occurred when the file position was not
1265 at the end of the file and write() was called with enough data to
1266 extend past the end of the file.
1267
1268- Fixed a bug that caused Tkinter error messages to get lost on
1269 Windows. The bug was fixed by replacing direct use of
1270 interp->result with Tcl_GetStringResult(interp).
1271
1272- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1273 redirect response.
1274
1275- Several changes were made to distutils: Some debugging code was
1276 removed from util. Fixed the installer used when an external zip
1277 program (like WinZip) is not found; the source code for this
1278 installer is in Misc/distutils. check_lib() was modified to behave
1279 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1280 test for whether installed modules are on sys.path was changed to
1281 use both normcase() and normpath().
1282
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001283- Several minor bugs were fixed in the xml package (the minidom,
1284 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001285
1286- The regression test driver (regrtest.py) behavior when invoked with
1287 -l changed: It now reports a count of objects that are recognized as
1288 garbage but not freed by the garbage collector.
1289
Tim Peters989b7b92000-10-16 20:24:53 +00001290- The regression test for the math module was changed to test
1291 exceptional behavior when the test is run in verbose mode. Python
1292 cannot yet guarantee consistent exception behavior across platforms,
1293 so the exception part of test_math is run only in verbose mode, and
1294 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001295
1296Internals
1297
1298- PyOS_CheckStack() has been disabled on Win64, where it caused
1299 test_sre to fail.
1300
1301Build issues
1302
1303- Changed compiler flags, so that gcc is always invoked with -Wall and
1304 -Wstrict-prototypes. Users compiling Python with GCC should see
1305 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001306 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001307 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001308
Tim Petersa3a3a032000-11-30 05:22:44 +00001309- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001310
1311Tools and other miscellany
1312
1313- The compiler in Tools/compiler was updated to support the new
1314 language features introduced in 2.0: extended print statement, list
1315 comprehensions, and augmented assignments. The new compiler should
1316 also be backwards compatible with Python 1.5.2; the compiler will
1317 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001318 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001319
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001320What's new in 2.0 release candidate 1 (since beta 2)?
1321=====================================================
1322
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001323What is release candidate 1?
1324
1325We believe that release candidate 1 will fix all known bugs that we
1326intend to fix for the 2.0 final release. This release should be a bit
1327more stable than the previous betas. We would like to see even more
1328widespread testing before the final release, so we are producing this
1329release candidate. The final release will be exactly the same unless
1330any show-stopping (or brown bag) bugs are found by testers of the
1331release candidate.
1332
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001333All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001334to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001335
1336Core language, builtins, and interpreter
1337
1338- A bug that caused crashes when __coerce__ was used with augmented
1339 assignment, e.g. +=, was fixed.
1340
1341- Raise ZeroDivisionError when raising zero to a negative number,
1342 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1343 power operator and the result of math.pow(0.0, -2.0) will vary by
1344 platform. On Linux, it raises a ValueError.
1345
1346- A bug in Unicode string interpolation was fixed that occasionally
1347 caused errors with formats including "%%". For example, the
1348 following expression "%% %s" % u"abc" no longer raises a TypeError.
1349
1350- Compilation of deeply nested expressions raises MemoryError instead
1351 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1352
1353- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1354 rendering them useless. They are now written in binary mode again.
1355
1356Standard library
1357
1358- Keyword arguments are now accepted for most pattern and match object
1359 methods in SRE, the standard regular expression engine.
1360
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001361- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001362 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001363
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001364- Several bugs in the Unicode handling and error handling in _tkinter
1365 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001366
1367- Fix memory management errors in Merge() and Tkapp_Call() routines.
1368
1369- Several changes were made to cStringIO to make it compatible with
1370 the file-like object interface and with StringIO. If operations are
1371 performed on a closed object, an exception is raised. The truncate
1372 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001373 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001374
1375- There were many changes made to the linuxaudiodev module and its
1376 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001377 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001378
1379 Note that this module is named poorly, because it should work
1380 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001381 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001382
1383 The module now raises exceptions when errors occur instead of
1384 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1385 audio) and defines a getptr() method that calls the
1386 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1387
1388- The library_version attribute, introduced in an earlier beta, was
1389 removed because it can not be supported with early versions of the C
1390 readline library, which provides no way to determine the version at
1391 compile-time.
1392
1393- The binascii module is now enabled on Win64.
1394
Tim Peters46446d62000-10-09 21:19:31 +00001395- tokenize.py no longer suffers "recursion depth" errors when parsing
1396 programs with very long string literals.
1397
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001398Internals
1399
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001400- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001401 which is called when the interpreter starts up to determine where
1402 the standard library is installed. These vulnerabilities affect all
1403 previous versions of Python and can be exploited by setting very
1404 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1405 setuid Python script, although use of the wrapper in
1406 Misc/setuid-prog.c will eliminate the vulnerability.
1407
1408- Fixed garbage collection bugs in instance creation that were
1409 triggered when errors occurred during initialization. The solution,
1410 applied in cPickle and in PyInstance_New(), is to call
1411 PyObject_GC_Init() after the initialization of the object's
1412 container attributes is complete.
1413
1414- pyexpat adds definitions of PyModule_AddStringConstant and
1415 PyModule_AddObject if the Python version is less than 2.0, which
1416 provides compatibility with PyXML on Python 1.5.2.
1417
1418- If the platform has a bogus definition for LONG_BIT (the number of
1419 bits in a long), an error will be reported at compile time.
1420
1421- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1422 collection crashes and possibly other, unreported crashes.
1423
1424- Fixed a memory leak in _PyUnicode_Fini().
1425
1426Build issues
1427
1428- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001429 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001430 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001431
1432- The mmap.PAGESIZE constant is now initialized using sysconf when
1433 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1434
1435- The md5 file should now compile on all platforms.
1436
1437- The select module now compiles on platforms that do not define
1438 POLLRDNORM and related constants.
1439
1440- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001441 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001442
Jeremy Hylton10921202000-10-09 18:34:12 +00001443- BeOS: A number of changes were made to the build and installation
1444 process. ar-fake now operates on a directory of object files.
1445 dl_export.h is gone, and its macros now appear on the mwcc command
1446 line during build on PPC BeOS.
1447
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001448- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001449 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001450
1451- Cygwin: Support for shared libraries, Tkinter, and sockets.
1452
1453- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1454
1455Tools and other miscellany
1456
1457- Removed debugging prints from main used with freeze.
1458
Tim Peters46446d62000-10-09 21:19:31 +00001459- IDLE auto-indent no longer crashes when it encounters Unicode
1460 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001461
1462What's new in 2.0 beta 2 (since beta 1)?
1463========================================
1464
1465Core language, builtins, and interpreter
1466
Tim Peters482c0212000-09-26 06:33:09 +00001467- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001468 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001469
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001470- Add -h and -V command line options to print the usage message and
1471 Python version number and exit immediately.
1472
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001473- eval() and exec accept Unicode objects as code parameters.
1474
1475- getattr() and setattr() now also accept Unicode objects for the
1476 attribute name, which are converted to strings using the default
1477 encoding before lookup.
1478
1479- Multiplication on string and Unicode now does proper bounds
1480 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1481 string is too long."
1482
1483- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001484 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001485
Jeremy Hylton1b618592000-09-26 05:32:36 +00001486
1487Standard library and extensions
1488
Guido van Rossum5b08f132001-04-16 02:05:23 +00001489- socket module: the OpenSSL code now adds support for RAND_status()
1490 and EGD (Entropy Gathering Device).
1491
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001492- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001493 argument checking; it still takes no arguments.
1494
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001495- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001496
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001497- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001498
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001499- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001500
1501- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001502 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001503
1504- copy: Copy Unicode objects atomically.
1505
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001506- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001507
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001508- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001509
Fred Drake67233bc2000-09-26 16:40:27 +00001510- dbm: Add get() and setdefault() methods to dbm object. Add constant
1511 `library' to module that names the library used. Added doc strings
1512 and method names to error messages. Uses configure to determine
1513 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1514 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001515
1516- distutils: Update to version 0.9.3.
1517
1518- dl: Add several dl.RTLD_ constants.
1519
1520- fpectl: Now supported on FreeBSD.
1521
1522- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1523 found by the collector will be saved in gc.garbage. This is useful
1524 for debugging a program that creates reference cycles.
1525
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001526- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001527 of HTTP class. Do not close socket on zero-length response. Do not
1528 crash when server sends invalid content-length header.
1529
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001530- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001531
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001532- marshal: When reading a short, sign-extend on platforms where shorts
1533 are bigger than 16 bits. When reading a long, repair the unportable
1534 sign extension that was being done for 64-bit machines. (It assumed
1535 that signed right shift sign-extends.)
1536
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001537- operator: Add contains(), invert(), __invert__() as aliases for
1538 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001539
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001540- os: Add support for popen2() and popen3() on all platforms where
1541 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001542
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001543- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001544 clicking on a file in Explorer (or passing the file name to the
1545 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001546
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001547- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001548 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001549
1550- pickle: Now raises ValueError when an invalid pickle that contains
1551 a non-string repr where a string repr was expected. This behavior
1552 matches cPickle.
1553
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001554- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001555
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001556- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001557
1558- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001559 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001560 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001561
1562- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001563 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001564
1565- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001566 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001567 few cycles during startup since the first call to
1568 setdefaultencoding() will initialize the codec registry and the
1569 encodings package.
1570
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001571- socket: Support for size hint in readlines() method of object returned
1572 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001573
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001574- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001575 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001576 is followed by whitespace.
1577
Tim Petersa3a3a032000-11-30 05:22:44 +00001578- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001579
1580- struct: Check ranges for bytes and shorts.
1581
1582- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001583 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001584
1585- Tkinter: Image objects are now guaranteed to have unique ids. Set
1586 event.delta to zero if Tk version doesn't support mousewheel.
1587 Removed some debugging prints.
1588
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001589- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001590
Fred Drake67233bc2000-09-26 16:40:27 +00001591- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001592 which works around a bug in Norton AntiVirus 2000 that leads directly
1593 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001594
1595- xml: New version detection code allows PyXML to override standard
1596 XML package if PyXML version is greater than 0.6.1.
1597
Fred Drake64bb3802000-09-26 16:21:35 +00001598- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1599 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1600 tree only for nodes which are sufficiently interesting to a specific
1601 application. Does not provide the HTML-specific extensions. Still
1602 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001603
Fred Drake64bb3802000-09-26 16:21:35 +00001604- xml.sax: SAX 2 support for Python, including all the handler
1605 interfaces needed to process XML 1.0 compliant XML. Some
1606 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001607
Fred Drake64bb3802000-09-26 16:21:35 +00001608- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1609 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001610
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001611
Jeremy Hylton1b618592000-09-26 05:32:36 +00001612C API
1613
1614- Add three new convenience functions for module initialization --
1615 PyModule_AddObject(), PyModule_AddIntConstant(), and
1616 PyModule_AddStringConstant().
1617
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001618- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001619 removed and add #error to Python.h if NULL isn't defined after
1620 #include of stdio.h.
1621
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001622- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001623 backwards compatibility (at the source level) with old extensions.
1624
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001625- A wrapper API was added for signal() and sigaction(). Instead of
1626 either function, always use PyOS_getsig() to get a signal handler
1627 and PyOS_setsig() to set one. A new convenience typedef
1628 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001629
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001630- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001631 internal data buffer and size of a string object -- or the default
1632 encoded version of a Unicode object.
1633
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001634- PyString_Size() and PyString_AsString() accept Unicode objects.
1635
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001636- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001637 exists). INT_MAX and LONG_MAX will always be defined, even if
1638 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001639
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001640- PyFloat_FromString takes a second argument, pend, that was
1641 effectively useless. It is now officially useless but preserved for
1642 backwards compatibility. If the pend argument is not NULL, *pend is
1643 set to NULL.
1644
1645- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1646 for the attribute name. See note on getattr() above.
1647
1648- A few bug fixes to argument processing for Unicode.
1649 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1650 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1651 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001652 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001653
1654- Py_BuildValue accepts B format (for bgen-generated code).
1655
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001656
Jeremy Hylton1b618592000-09-26 05:32:36 +00001657Internals
1658
1659- On Unix, fix code for finding Python installation directory so that
1660 it works when argv[0] is a relative path.
1661
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001662- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001663 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001664 rather than by generating a copy of the object.
1665
Tim Peters482c0212000-09-26 06:33:09 +00001666- Several of the internal Unicode tables are much smaller now, and
1667 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001668
Jeremy Hylton97693b02000-09-26 17:42:51 +00001669- In the garbage collector: Fixed bug in collection of tuples. Fixed
1670 bug that caused some instances to be removed from the container set
1671 while they were still live. Fixed parsing in gc.set_debug() for
1672 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001673
1674- Fixed refcount problem in instance deallocation that only occurred
1675 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1676
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001677- On Windows, getpythonregpath is now protected against null data in
1678 registry key.
1679
1680- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001681 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001682
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001683
Jeremy Hylton1b618592000-09-26 05:32:36 +00001684Build and platform-specific issues
1685
1686- Better support of GNU Pth via --with-pth configure option.
1687
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001688- Python/C API now properly exposed to dynamically-loaded extension
1689 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001690
1691- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1692 Don't define MS_SYNC to be zero when it is undefined. Added missing
1693 prototypes in posixmodule.c.
1694
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001695- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001696 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001697
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001698- Fix largefile support on older NetBSD systems and OpenBSD by adding
1699 define for TELL64.
1700
1701
1702Tools and other miscellany
1703
1704- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1705
1706- freeze: The modulefinder now works with 2.0 opcodes.
1707
Tim Petersa3a3a032000-11-30 05:22:44 +00001708- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001709 Move hackery of sys.argv until after the Tk instance has been
1710 created, which allows the application-specific Tkinter
1711 initialization to be executed if present; also pass an explicit
1712 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001713
Jeremy Hylton1b618592000-09-26 05:32:36 +00001714
1715What's new in 2.0 beta 1?
1716=========================
1717
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001718Source Incompatibilities
1719------------------------
1720
1721None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1722such as single-argument append(), connect() and bind(), and changes to
1723str(long) and repr(float).
1724
1725
1726Binary Incompatibilities
1727------------------------
1728
1729- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1730with Python 2.0; these extensions will have to be rebuilt for Python
17312.0.
1732
1733- On Windows, attempting to import a third party extension built for
1734Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1735can do about this. Check your PYTHONPATH environment variable!
1736
1737- Python bytecode files (*.pyc and *.pyo) are not compatible between
1738releases.
1739
1740
1741Overview of Changes Since 1.6
1742-----------------------------
1743
1744There are many new modules (including brand new XML support through
1745the xml package, and i18n support through the gettext module); a list
1746of all new modules is included below. Lots of bugs have been fixed.
1747
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001748The process for making major new changes to the language has changed
1749since Python 1.6. Enhancements must now be documented by a Python
1750Enhancement Proposal (PEP) before they can be accepted.
1751
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001752There are several important syntax enhancements, described in more
1753detail below:
1754
1755 - Augmented assignment, e.g. x += 1
1756
1757 - List comprehensions, e.g. [x**2 for x in range(10)]
1758
1759 - Extended import statement, e.g. import Module as Name
1760
1761 - Extended print statement, e.g. print >> file, "Hello"
1762
1763Other important changes:
1764
1765 - Optional collection of cyclical garbage
1766
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001767Python Enhancement Proposal (PEP)
1768---------------------------------
1769
1770PEP stands for Python Enhancement Proposal. A PEP is a design
1771document providing information to the Python community, or describing
1772a new feature for Python. The PEP should provide a concise technical
1773specification of the feature and a rationale for the feature.
1774
1775We intend PEPs to be the primary mechanisms for proposing new
1776features, for collecting community input on an issue, and for
1777documenting the design decisions that have gone into Python. The PEP
1778author is responsible for building consensus within the community and
1779documenting dissenting opinions.
1780
1781The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001782
1783Augmented Assignment
1784--------------------
1785
1786This must have been the most-requested feature of the past years!
1787Eleven new assignment operators were added:
1788
Guido van Rossume905e952000-09-05 12:42:46 +00001789 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001790
1791For example,
1792
1793 A += B
1794
1795is similar to
1796
1797 A = A + B
1798
1799except that A is evaluated only once (relevant when A is something
1800like dict[index].attr).
1801
1802However, if A is a mutable object, A may be modified in place. Thus,
1803if A is a number or a string, A += B has the same effect as A = A+B
1804(except A is only evaluated once); but if a is a list, A += B has the
1805same effect as A.extend(B)!
1806
1807Classes and built-in object types can override the new operators in
1808order to implement the in-place behavior; the not-in-place behavior is
1809used automatically as a fallback when an object doesn't implement the
1810in-place behavior. For classes, the method name is derived from the
1811method name for the corresponding not-in-place operator by inserting
1812an 'i' in front of the name, e.g. __iadd__ implements in-place
1813__add__.
1814
1815Augmented assignment was implemented by Thomas Wouters.
1816
1817
1818List Comprehensions
1819-------------------
1820
1821This is a flexible new notation for lists whose elements are computed
1822from another list (or lists). The simplest form is:
1823
1824 [<expression> for <variable> in <sequence>]
1825
Guido van Rossum56db0952000-09-06 23:34:25 +00001826For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001827This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001828
1829You can also add a condition:
1830
1831 [<expression> for <variable> in <sequence> if <condition>]
1832
1833For example, [w for w in words if w == w.lower()] would yield the list
1834of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001835than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001836
1837You can also have nested for loops and more than one 'if' clause. For
1838example, here's a function that flattens a sequence of sequences::
1839
1840 def flatten(seq):
1841 return [x for subseq in seq for x in subseq]
1842
1843 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1844
1845This prints
1846
1847 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1848
1849List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001850Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001851
1852
1853Extended Import Statement
1854-------------------------
1855
1856Many people have asked for a way to import a module under a different
1857name. This can be accomplished like this:
1858
1859 import foo
1860 bar = foo
1861 del foo
1862
1863but this common idiom gets old quickly. A simple extension of the
1864import statement now allows this to be written as follows:
1865
1866 import foo as bar
1867
1868There's also a variant for 'from ... import':
1869
1870 from foo import bar as spam
1871
1872This also works with packages; e.g. you can write this:
1873
1874 import test.regrtest as regrtest
1875
1876Note that 'as' is not a new keyword -- it is recognized only in this
1877context (this is only possible because the syntax for the import
1878statement doesn't involve expressions).
1879
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001880Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001881
1882
1883Extended Print Statement
1884------------------------
1885
1886Easily the most controversial new feature, this extension to the print
1887statement adds an option to make the output go to a different file
1888than the default sys.stdout.
1889
1890For example, to write an error message to sys.stderr, you can now
1891write:
1892
1893 print >> sys.stderr, "Error: bad dog!"
1894
1895As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001896evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001897
1898 print >> None, "Hello world"
1899
1900is equivalent to
1901
1902 print "Hello world"
1903
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001904Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001905
1906
1907Optional Collection of Cyclical Garbage
1908---------------------------------------
1909
1910Python is now equipped with a garbage collector that can hunt down
1911cyclical references between Python objects. It's no replacement for
1912reference counting; in fact, it depends on the reference counts being
1913correct, and decides that a set of objects belong to a cycle if all
1914their reference counts can be accounted for from their references to
1915each other. This devious scheme was first proposed by Eric Tiedemann,
1916and brought to implementation by Neil Schemenauer.
1917
1918There's a module "gc" that lets you control some parameters of the
1919garbage collection. There's also an option to the configure script
1920that lets you enable or disable the garbage collection. In 2.0b1,
1921it's on by default, so that we (hopefully) can collect decent user
1922experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001923performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001924off by default in the final 2.0 release.
1925
1926
1927Smaller Changes
1928---------------
1929
1930A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1931map(None, seq1, seq2, ...) when the sequences have the same length;
1932i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1933the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001934zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001935
1936sys.version_info is a tuple (major, minor, micro, level, serial).
1937
1938Dictionaries have an odd new method, setdefault(key, default).
1939dict.setdefault(key, default) returns dict[key] if it exists; if not,
1940it sets dict[key] to default and returns that value. Thus:
1941
1942 dict.setdefault(key, []).append(item)
1943
1944does the same work as this common idiom:
1945
1946 if not dict.has_key(key):
1947 dict[key] = []
1948 dict[key].append(item)
1949
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001950There are two new variants of SyntaxError that are raised for
1951indentation-related errors: IndentationError and TabError.
1952
1953Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1954escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001955
1956The limits on the size of expressions and file in Python source code
1957have been raised from 2**16 to 2**32. Previous versions of Python
1958were limited because the maximum argument size the Python VM accepted
1959was 2**16. This limited the size of object constructor expressions,
1960e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1961limit was raised thanks to a patch by Charles Waldman that effectively
1962fixes the problem. It is now much more likely that you will be
1963limited by available memory than by an arbitrary limit in Python.
1964
1965The interpreter's maximum recursion depth can be modified by Python
1966programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1967limit is the maximum number of recursive calls that can be made by
1968Python code. The limit exists to prevent infinite recursion from
1969overflowing the C stack and causing a core dump. The default value is
19701000. The maximum safe value for a particular platform can be found
1971by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001972
1973New Modules and Packages
1974------------------------
1975
1976atexit - for registering functions to be called when Python exits.
1977
1978imputil - Greg Stein's alternative API for writing custom import
1979hooks.
1980
1981pyexpat - an interface to the Expat XML parser, contributed by Paul
1982Prescod.
1983
1984xml - a new package with XML support code organized (so far) in three
1985subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1986would fill a volume. There's a special feature whereby a
1987user-installed package named _xmlplus overrides the standard
1988xmlpackage; this is intended to give the XML SIG a hook to distribute
1989backwards-compatible updates to the standard xml package.
1990
1991webbrowser - a platform-independent API to launch a web browser.
1992
1993
Guido van Rossume905e952000-09-05 12:42:46 +00001994Changed Modules
1995---------------
1996
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001997array -- new methods for array objects: count, extend, index, pop, and
1998remove
1999
2000binascii -- new functions b2a_hex and a2b_hex that convert between
2001binary data and its hex representation
2002
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002003calendar -- Many new functions that support features including control
2004over which day of the week is the first day, returning strings instead
2005of printing them. Also new symbolic constants for days of week,
2006e.g. MONDAY, ..., SUNDAY.
2007
2008cgi -- FieldStorage objects have a getvalue method that works like a
2009dictionary's get method and returns the value attribute of the object.
2010
2011ConfigParser -- The parser object has new methods has_option,
2012remove_section, remove_option, set, and write. They allow the module
2013to be used for writing config files as well as reading them.
2014
2015ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002016optionally support the RFC 959 REST command.
2017
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002018gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002019
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002020httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2021the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002022
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002023locale -- implement getdefaultlocale for Win32 and Macintosh
2024
2025marshal -- no longer dumps core when marshaling deeply nested or
2026recursive data structures
2027
2028os -- new functions isatty, seteuid, setegid, setreuid, setregid
2029
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002030os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2031support under Unix.
2032
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002033os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002034
2035os.path -- fix semantics of os.path.commonprefix
2036
2037smtplib -- support for sending very long messages
2038
2039socket -- new function getfqdn()
2040
2041readline -- new functions to read, write and truncate history files.
2042The readline section of the library reference manual contains an
2043example.
2044
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002045select -- add interface to poll system call
2046
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002047shutil -- new copyfileobj function
2048
2049SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2050HTTP server.
2051
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002052Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002053
2054urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002055e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002056
2057whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002058
2059
2060Obsolete Modules
2061----------------
2062
2063None. However note that 1.6 made a whole slew of modules obsolete:
2064stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2065poly, zmod, strop, util, whatsound.
2066
2067
2068Changed, New, Obsolete Tools
2069----------------------------
2070
Tim Peters8b092332000-09-05 20:15:25 +00002071None.
Guido van Rossume905e952000-09-05 12:42:46 +00002072
2073
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002074C-level Changes
2075---------------
2076
2077Several cleanup jobs were carried out throughout the source code.
2078
2079All C code was converted to ANSI C; we got rid of all uses of the
2080Py_PROTO() macro, which makes the header files a lot more readable.
2081
2082Most of the portability hacks were moved to a new header file,
2083pyport.h; several other new header files were added and some old
2084header files were removed, in an attempt to create a more rational set
2085of header files. (Few of these ever need to be included explicitly;
2086they are all included by Python.h.)
2087
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002088Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002089and Win64, especially for the new Intel Itanium processor. Mick also
2090added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002091
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002092The C APIs to return an object's size have been update to consistently
2093use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2094previous versions, the abstract interfaces used PyXXX_Length and the
2095concrete interfaces used PyXXX_Size. The old names,
2096e.g. PyObject_Length, are still available for backwards compatibility
2097at the API level, but are deprecated.
2098
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002099The PyOS_CheckStack function has been implemented on Windows by
2100Fredrik Lundh. It prevents Python from failing with a stack overflow
2101on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002102
2103The GC changes resulted in creation of two new slots on object,
2104tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002105the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002106
2107The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002108C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002109
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002110PyErr_Format has been updated to automatically calculate the size of
2111the buffer needed to hold the formatted result string. This change
2112prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002113
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002114New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002115
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002116PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2117that are the same as their non-Ex counterparts except they take an
2118extra flag argument that tells them to close the file when done.
2119
2120XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002121
Tim Peters8b092332000-09-05 20:15:25 +00002122
2123Windows Changes
2124---------------
2125
2126New popen2/popen3/peopen4 in os module (see Changed Modules above).
2127
2128os.popen is much more usable on Windows 95 and 98. See Microsoft
2129Knowledge Base article Q150956. The Win9x workaround described there
2130is implemented by the new w9xpopen.exe helper in the root of your
2131Python installation. Note that Python uses this internally; it is not
2132a standalone program.
2133
2134Administrator privileges are no longer required to install Python
2135on Windows NT or Windows 2000. If you have administrator privileges,
2136Python's registry info will be written under HKEY_LOCAL_MACHINE.
2137Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002138under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002139uses of Python, but will prevent some advanced uses from working
2140(for example, running a Python script as an NT service, or possibly
2141from CGI).
2142
2143[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2144installer; instead, it installs the needed Tcl/Tk files directly in the
2145Python directory. If you already have a Tcl/Tk installation, this
2146wastes some disk space (about 4 Megs) but avoids problems with
2147conflicting Tcl/Tk installations, and makes it much easier for Python
2148to ensure that Tcl/Tk can find all its files.
2149
2150[This was new in 1.6] The Windows installer now installs by default in
2151\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2152
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002153
2154Updates to the changes between 1.5.2 and 1.6
2155--------------------------------------------
2156
2157The 1.6 NEWS file can't be changed after the release is done, so here
2158is some late-breaking news:
2159
2160New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2161and changes to getlocale() and setlocale().
2162
2163The new module is now enabled per default.
2164
2165It is not true that the encodings codecs cannot be used for normal
2166strings: the string.encode() (which is also present on 8-bit strings
2167!) allows using them for 8-bit strings too, e.g. to convert files from
2168cp1252 (Windows) to latin-1 or vice-versa.
2169
2170Japanese codecs are available from Tamito KAJIYAMA:
2171http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2172
2173
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002174======================================================================