blob: 5ddf80a2ceb5b60da3e394e962806bd4bb56d71c [file] [log] [blame]
Tim Petersedc99312001-08-22 21:36:50 +00001What's New in Python 2.2a3?
2===========================
3
4Core
5
6Library
7
8Tools
9
10Build
11
12New platforms
13
14Tests
15
16Windows
17
18
Tim Peters20f51a72001-07-21 02:31:40 +000019What's New in Python 2.2a2?
20===========================
21
Martin v. Löwis339d0f72001-08-17 18:39:25 +000022Build
23
Barry Warsaw18b2ecf2001-08-22 20:26:56 +000024- Tim Peters developed a brand new Windows installer using Wise 8.1,
25 generously donated to us by Wise Solutions.
26
Martin v. Löwis339d0f72001-08-17 18:39:25 +000027- configure supports a new option --enable-unicode, with the values
28 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
29 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +000030
Jack Jansen32ce0cd2001-08-21 19:28:20 +000031- A new configure option --enable-framework builds a Mac OS X framework,
32 which "make frameworkinstall" will install. This provides a starting
33 point for more mac-like functionality, join pythonmac-sig@python.org
34 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +000035
Barry Warsaw6f3410d2001-08-22 04:08:41 +000036- The NeXT platform is no longer supported.
37
38- The `new' module is now statically linked.
39
Tim Peters0afb6092001-08-15 06:06:44 +000040Tools
41
42- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +000043 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +000044 the module docstring for details.
45
Tim Peters20f51a72001-07-21 02:31:40 +000046Tests
47
Tim Peters5e824c32001-08-12 22:25:01 +000048- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +000049 platforms, allowing to give clearer test result output. regrtest
50 also has optional --use/-u switch to run normally disabled tests
51 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +000052
Tim Peters20f51a72001-07-21 02:31:40 +000053- Several new tests in the standard test suite, with special thanks to
54 Nick Mathewson.
55
56Core
57
Barry Warsaw6f3410d2001-08-22 04:08:41 +000058- The floor division operator // has been added as outlined in PEP
59 238. The / operator still provides classic division (and will until
60 Python 3.0) unless "from __future__ import division" is included, in
61 which case the / operator will provide true division. The operator
62 module provides truediv() and floordiv() functions. Augmented
63 assignment variants are included, as are the equivalent overloadable
64 methods and C API methods. See the PEP for a full discussion:
65 <http://python.sf.net/peps/pep-0238.html>
66
Tim Peters6cd6a822001-08-17 22:11:27 +000067- Future statements are now effective in simulated interactive shells
68 (like IDLE). This should "just work" by magic, but read Michael
69 Hudson's "Future statements in simulated shells" PEP 264 for full
70 details: <http://python.sf.net/peps/pep-0264.html>.
71
Guido van Rossumf86ddd22001-08-17 21:21:04 +000072- The type/class unification (PEP 252-253) was integrated into the
73 trunk and is not so tentative any more (the exact specification of
74 some features is still tentative). A lot of work has done on fixing
75 bugs and adding robustness and features (performance still has to
76 come a long way).
77
Marc-André Lemburg888fac02001-07-31 14:24:31 +000078- Warnings about a mismatch in the Python API during extension import
79 now use the Python warning framework (which makes it possible to
80 write filters for these warnings).
81
Barry Warsaw9b3be7f2001-08-14 18:35:02 +000082- A function's __dict__ (aka func_dict) will now always be a
83 dictionary. It used to be possible to delete it or set it to None,
84 but now both actions raise TypeErrors. It is still legal to set it
85 to a dictionary object. Getting func.__dict__ before any attributes
86 have been assigned now returns an empty dictionary instead of None.
87
Marc-André Lemburgd6277912001-07-31 14:42:42 +000088Library
89
Tim Peters5e824c32001-08-12 22:25:01 +000090- New class Differ and new functions ndiff() and restore() in difflib.py.
91 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +000092 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +000093
Marc-André Lemburgd6277912001-07-31 14:42:42 +000094- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
95 value using the minimal quoting required for the value; more
96 reliable than using xml.sax.saxutils.escape() for attribute values.
97
98- Readline completion support for cmd.Cmd was added.
99
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000100- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
101
102- Added function threading.BoundedSemaphore()
103
104- Added Ka-Ping Yee's cgitb.py module.
105
106- The `new' module now exposes the CO_xxx flags.
107
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000108New platforms
109
110C API
111
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000112- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
113 which provide a cross-platform implementations for the
114 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
115 the standard sprintf() and vsprintf() C lib APIs, these versions
116 apply bounds checking on the used buffer which enhances protection
117 against buffer overruns.
118
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000119- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000120 and extensions using different Unicode widths is rendered next to
121 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000122 will result in an ImportError. Unicode extensions writers must make
123 sure to check the Unicode width compatibility in their extensions by
124 using at least one of the mangled Unicode APIs in the extension.
125
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000126- Two new flags METH_NOARGS and METH_O are available in method definition
127 tables to simplify implementation of methods with no arguments and a
128 single untyped argument. Calling such methods is more efficient than
129 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
130 deprecated.
131
Tim Petersc1731372001-08-04 08:12:36 +0000132Windows
133
134- "import module" now compiles module.pyw if it exists and nothing else
135 relevant is found.
136
Tim Peters20f51a72001-07-21 02:31:40 +0000137
Guido van Rossum55a78992001-07-17 17:22:32 +0000138What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000139===========================
140
141Core
Tim Petersa814db52001-05-14 07:05:58 +0000142
Tim Peters6d6c1a32001-08-02 04:15:00 +0000143- TENTATIVELY, a large amount of code implementing much of what's
144 described in PEP 252 (Making Types Look More Like Classes) and PEP
145 253 (Subtyping Built-in Types) was added. This will be released
146 with Python 2.2a1. Documentation will be provided separately
147 through http://www.python.org/2.2/. The purpose of releasing this
148 with Python 2.2a1 is to test backwards compatibility. It is
149 possible, though not likely, that a decision is made not to release
150 this code as part of 2.2 final, if any serious backwards
151 incompapatibilities are found during alpha testing that cannot be
152 repaired.
153
Guido van Rossum55a78992001-07-17 17:22:32 +0000154- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000155 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000156 more 'yield' statements. See PEP 255. Since this adds a new
157 keyword to the language, this feature must be enabled by including a
158 future statement: "from __future__ import generators" (see PEP 236).
159 Generators will become a standard feature in a future release
160 (probably 2.3). Without this future statement, 'yield' remains an
161 ordinary identifier, but a warning is issued each time it is used.
162 (These warnings currently don't conform to the warnings framework of
163 PEP 230; we intend to fix this in 2.2a2.)
164
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000165- The UTF-16 codec was modified to be more RFC compliant. It will now
166 only remove BOM characters at the start of the string and then
167 only if running in native mode (UTF-16-LE and -BE won't remove a
168 leading BMO character).
169
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000170- Strings now have a new method .decode() to complement the already
171 existing .encode() method. These two methods provide direct access
172 to the corresponding decoders and encoders of the registered codecs.
173
174 To enhance the usability of the .encode() method, the special
175 casing of Unicode object return values was dropped (Unicode objects
176 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000177
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000178 Both methods will now return whatever the codec in charge of the
179 requested encoding returns as object, e.g. Unicode codecs will
180 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
181 will return u"äöü"). This enables codec writer to create codecs
182 for various simple to use conversions.
183
184 New codecs were added to demonstrate these new features (the .encode()
185 and .decode() columns indicate the type of the returned objects):
186
187 Name | .encode() | .decode() | Description
188 ----------------------------------------------------------------------
189 uu | string | string | UU codec (e.g. for email)
190 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000191 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000192 zlib | string | string | zlib compression
193 hex | string | string | 2-byte hex codec
194 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
195
Mark Hammond2a0af792001-05-14 03:09:36 +0000196- Some operating systems now support the concept of a default Unicode
197 encoding for file system operations. Notably, Windows supports 'mbcs'
198 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000199 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000200 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000201
202 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000203 functions that return filenames (such as os.listdir()) to return Python
204 string objects pre-encoded using the default file system encoding for
205 the platform. As this encoding is likely to be different from Python's
206 default encoding, converting this name to a Unicode object before passing
207 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000208 would attempt to use its default encoding (generally ASCII) rather than
209 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000210
Tim Petersa814db52001-05-14 07:05:58 +0000211 In general, this change simply removes surprises when working with
212 Unicode and the file system, making these operations work as you expect,
213 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000214 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000215
Tim Peters61dff2b2001-05-08 15:43:37 +0000216- Float (and complex) literals in source code were evaluated to full
217 precision only when running from a .py file; the same code loaded from a
218 .pyc (or .pyo) file could suffer numeric differences starting at about the
219 12th significant decimal digit. For example, on a machine with IEEE-754
220 floating arithmetic,
221
222 x = 9007199254740992.0
223 print long(x)
224
225 printed 9007199254740992 if run directly from .py, but 9007199254740000
226 if from a compiled (.pyc or .pyo) file. This was due to marshal using
227 str(float) instead of repr(float) when building code objects. marshal
228 now uses repr(float) instead, which should reproduce floats to full
229 machine precision (assuming the platform C float<->string I/O conversion
230 functions are of good quality).
231
232 This may cause floating-point results to change in some cases, and
233 usually for the better, but may also cause numerically unstable
234 algorithms to break.
235
Tim Peters2f228e72001-05-13 00:19:31 +0000236- The implementation of dicts suffers fewer collisions, which has speed
237 benefits. However, the order in which dict entries appear in dict.keys(),
238 dict.values() and dict.items() may differ from previous releases for a
239 given dict. Nothing is defined about this order, so no program should
240 rely on it. Nevertheless, it's easy to write test cases that rely on the
241 order by accident, typically because of printing the str() or repr() of a
242 dict to an "expected results" file. See Lib/test/test_support.py's new
243 sortdict(dict) function for a simple way to display a dict in sorted
244 order.
245
Tim Peters7a3bfc32001-06-12 01:22:22 +0000246- Many other small changes to dicts were made, resulting in faster
247 operation along the most common code paths.
248
Guido van Rossum10315822001-05-01 20:54:30 +0000249- Dictionary objects now support the "in" operator: "x in dict" means
250 the same as dict.has_key(x).
251
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000252- The update() method of dictionaries now accepts generic mapping
253 objects. Specifically the argument object must support the .keys()
254 and __getitem__() methods. This allows you to say, for example,
255 {}.update(UserDict())
256
Guido van Rossum10315822001-05-01 20:54:30 +0000257- Iterators were added; this is a generalized way of providing values
258 to a for loop. See PEP 234. There's a new built-in function iter()
259 to return an iterator. There's a new protocol to get the next value
260 from an iterator using the next() method (in Python) or the
261 tp_iternext slot (in C). There's a new protocol to get iterators
262 using the __iter__() method (in Python) or the tp_iter slot (in C).
263 Iterating (i.e. a for loop) over a dictionary generates its keys.
264 Iterating over a file generates its lines.
265
Tim Petersf553f892001-05-01 20:45:31 +0000266- The following functions were generalized to work nicely with iterator
267 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000268 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000269 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
270 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000271 join() method of strings
272 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000273 'x in y' and 'x not in y' (PySequence_Contains() in C API)
274 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000275 right-hand side of assignment statements with multiple targets, such as
276 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000277
Tim Petersd85e1022001-05-11 21:51:48 +0000278- Accessing module attributes is significantly faster (for example,
279 random.random or os.path or yourPythonModule.yourAttribute).
280
Tim Peterse63415e2001-05-08 04:38:29 +0000281- Comparing dictionary objects via == and != is faster, and now works even
282 if the keys and values don't support comparisons other than ==.
283
Tim Peters95bf9392001-05-10 08:32:44 +0000284- Comparing dictionaries in ways other than == and != is slower: there were
285 insecurities in the dict comparison implementation that could cause Python
286 to crash if the element comparison routines for the dict keys and/or
287 values mutated the dicts. Making the code bulletproof slowed it down.
288
Tim Peterseb28ef22001-06-02 05:27:19 +0000289- Collisions in dicts are resolved via a new approach, which can help
290 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000291 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000292 faster now. Thanks to Christian Tismer for pointing out the cause and
293 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000294
Tim Peters52e155e2001-06-16 05:42:57 +0000295- repr() is much faster for large containers (dict, list, tuple).
296
297
Tim Petersa814db52001-05-14 07:05:58 +0000298Library
299
Fred Drake960fdf92001-07-20 18:38:26 +0000300- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
301 were added to the string module. These a locale-indenpendent
302 constants, unlike letters, lowercase, and uppercase. These are now
303 use in appropriate locations in the standard library.
304
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000305- The flags used in dlopen calls can now be configured using
306 sys.setdlopenflags and queried using sys.getdlopenflags.
307
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000308- Fredrik Lundh's xmlrpclib is now a standard library module. This
309 provides full client-side XML-RPC support. In addition,
310 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
311 one asyncore-based). Thanks to Eric Raymond for the documentation.
312
Guido van Rossum643d3912001-07-05 14:46:25 +0000313- The xrange() object is simplified: it no longer supports slicing,
314 repetition, comparisons, efficient 'in' checking, the tolist()
315 method, or the start, stop and step attributes. See PEP 260.
316
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000317- A new function fnmatch.filter to filter lists of file names was added.
318
Barry Warsawffd674d2001-05-22 16:00:10 +0000319- calendar.py uses month and day names based on the current locale.
320
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000321- strop is now *really* obsolete (this was announced before with 1.6),
322 and issues DeprecationWarning when used (except for the four items
323 that are still imported into string.py).
324
Tim Petersa814db52001-05-14 07:05:58 +0000325- Cookie.py now sorts key+value pairs by key in output strings.
326
327- pprint.isrecursive(object) didn't correctly identify recursive objects.
328 Now it does.
329
Tim Peters95b3f782001-05-14 18:39:41 +0000330- pprint functions now much faster for large containers (tuple, list, dict).
331
Tim Peters7b9542a2001-06-10 23:40:19 +0000332- New 'q' and 'Q' format codes in the struct module, corresponding to C
333 types "long long" and "unsigned long long" (on Windows, __int64). In
334 native mode, these can be used only when the platform C compiler supports
335 these types (when HAVE_LONG_LONG is #define'd by the Python config
336 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000337 In standard mode, 'q' and 'Q' are supported on all platforms, and are
338 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000339
Guido van Rossum83213cc2001-06-12 16:48:52 +0000340- The site module installs a new built-in function 'help' that invokes
341 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
342 it displays a message reminding the user to use 'help()' or
343 'help(object)'.
344
Tim Petersa814db52001-05-14 07:05:58 +0000345Tests
346
347- New test_mutants.py runs dict comparisons where the key and value
348 comparison operators mutute the dicts randomly during comparison. This
349 rapidly causes Python to crash under earlier releases (not for the faint
350 of heart: it can also cause Win9x to freeze or reboot!).
351
352- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000353 pprint.isreadable() return sensible results. Also verifies that simple
354 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000355
Tim Peters58e0a8c2001-05-14 22:32:33 +0000356New platforms
357
358- Python should compile and run out of the box using the Borland C
359 compiler (under Windows), thanks to Stephen Hansen.
Tim Petersf553f892001-05-01 20:45:31 +0000360
Tim Peters4324aa32001-05-28 22:30:08 +0000361C API
362
363- Removed the unused last_is_sticky argument from the internal
364 _PyTuple_Resize(). If this affects you, you were cheating.
365
366
Guido van Rossum55a78992001-07-17 17:22:32 +0000367======================================================================
368
369
Guido van Rossumffe13be2001-04-16 18:46:45 +0000370What's New in Python 2.1 (final)?
371=================================
372
373We only changed a few things since the last release candidate, all in
374Python library code:
375
376- A bug in the locale module was fixed that affected locales which
377 define no grouping for numeric formatting.
378
379- A few bugs in the weakref module's implementations of weak
380 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
381 and the test suite was updated to check for these bugs.
382
383- An old bug in the os.path.walk() function (introduced in Python
384 2.0!) was fixed: a non-existent file would cause an exception
385 instead of being ignored.
386
387- Fixed a few bugs in the new symtable module found by Neil Norwitz's
388 PyChecker.
389
390
Guido van Rossum5b08f132001-04-16 02:05:23 +0000391What's New in Python 2.1c2?
392===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000393
Guido van Rossum5b08f132001-04-16 02:05:23 +0000394A flurry of small changes, and one showstopper fixed in the nick of
395time made it necessary to release another release candidate. The list
396here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000397
Guido van Rossum5b08f132001-04-16 02:05:23 +0000398Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000399
Guido van Rossum5b08f132001-04-16 02:05:23 +0000400- Tim discovered a nasty bug in the dictionary code, caused by
401 PyDict_Next() calling dict_resize(), and the GC code's use of
402 PyDict_Next() violating an assumption in dict_items(). This was
403 fixed with considerable amounts of band-aid, but the net effect is a
404 saner and more robust implementation.
405
406- Made a bunch of symbols static that were accidentally global.
407
408Build and Ports
409
410- The setup.py script didn't check for a new enough version of zlib
411 (1.1.3 is needed). Now it does.
412
413- Changed "make clean" target to also remove shared libraries.
414
415- Added a more general warning about the SGI Irix optimizer to README.
416
417Library
418
419- Fix a bug in urllib.basejoin("http://host", "../file.html") which
420 omitted the slash between host and file.html.
421
422- The mailbox module's _Mailbox class contained a completely broken
423 and undocumented seek() method. Ripped it out.
424
425- Fixed a bunch of typos in various library modules (urllib2, smtpd,
426 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
427
428- Fixed a few last-minute bugs in unittest.
429
430Extensions
431
432- Reverted the patch to the OpenSSL code in socketmodule.c to support
433 RAND_status() and the EGD, and the subsequent patch that tried to
434 fix it for pre-0.9.5 versions; the problem with the patch is that on
435 some systems it issues a warning whenever socket is imported, and
436 that's unacceptable.
437
438Tests
439
440- Fixed the pickle tests to work with "import test.test_pickle".
441
442- Tweaked test_locale.py to actually run the test Windows.
443
444- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
445 not "wb" (which is not a valid mode at all).
446
447- Fix pstats browser crashes. Import readline if it exists to make
448 the user interface nicer.
449
450- Add "import thread" to the top of test modules that import the
451 threading module (test_asynchat and test_threadedtempfile). This
452 prevents test failures caused by a broken threading module resulting
453 from a previously caught failed import.
454
455- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
456 needed on some platforms (e.g. Solaris 8) when the tests are run
457 twice in succession.
458
459- Skip rather than fail test_sunaudiodev if no audio device is found.
460
461
462What's New in Python 2.1c1?
463===========================
464
465This list was significantly updated when 2.1c2 was released; the 2.1c1
466release didn't mention most changes that were actually part of 2.1c1:
467
468Legal
469
470- Copyright was assigned to the Python Software Foundation (PSF) and a
471 PSF license (very similar to the CNRI license) was added.
472
473- The CNRI copyright notice was updated to include 2001.
474
475Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000476
Guido van Rossumc9932722001-04-12 02:31:27 +0000477- After a public outcry, assignment to __debug__ is no longer illegal;
478 instead, a warning is issued. It will become illegal in 2.2.
479
Guido van Rossum5b08f132001-04-16 02:05:23 +0000480- Fixed a core dump with "%#x" % 0, and changed the semantics so that
481 "%#x" now always prepends "0x", even if the value is zero.
482
483- Fixed some nits in the bytecode compiler.
484
485- Fixed core dumps when calling certain kinds of non-functions.
486
487- Fixed various core dumps caused by reference count bugs.
488
489Build and Ports
490
491- Use INSTALL_SCRIPT to install script files.
492
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000493- New port: SCO Unixware 7, by Billy G. Allie.
494
Guido van Rossum5b08f132001-04-16 02:05:23 +0000495- Updated RISCOS port.
496
497- Updated BeOS port and notes.
498
499- Various other porting problems resolved.
500
501Library
502
503- The TERMIOS and SOCKET modules are now truly obsolete and
504 unnecessary. Their symbols are incorporated in the termios and
505 socket modules.
506
507- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
508 better tests for pickling.
509
510- threading: make Condition.wait() robust against KeyboardInterrupt.
511
512- zipfile: add support to zipfile to support opening an archive
513 represented by an open file rather than a file name. Fix bug where
514 the archive was not properly closed. Fixed a bug in this bugfix
515 where flush() was called for a read-only file.
516
517- imputil: added an uninstall() method to the ImportManager.
518
519- Canvas: fixed bugs in lower() and tkraise() methods.
520
521- SocketServer: API change (added overridable close_request() method)
522 so that the TCP server can explicitly close the request.
523
524- pstats: Eric Raymond added a simple interactive statistics browser,
525 invoked when the module is run as a script.
526
527- locale: fixed a problem in format().
528
529- webbrowser: made it work when the BROWSER environment variable has a
530 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
531 KDE 2. Fixed some other nits.
532
533- unittest: changes to allow using a different exception than
534 AssertionError, and added a few more function aliases. Some other
535 small changes.
536
537- urllib, urllib2: fixed redirect problems and a coupleof other nits.
538
539- asynchat: fixed a critical bug in asynchat that slipped through the
540 2.1b2 release. Fixed another rare bug.
541
542- Fix some unqualified except: clauses (always a bad code example).
543
544XML
545
546- pyexpat: new API get_version_string().
547
548- Fixed some minidom bugs.
549
550Extensions
551
552- Fixed a core dump in _weakref. Removed the weakref.mapping()
553 function (it adds nothing to the API).
554
555- Rationalized the use of header files in the readline module, to make
556 it compile (albeit with some warnings) with the very recent readline
557 4.2, without breaking for earlier versions.
558
559- Hopefully fixed a buffering problem in linuxaudiodev.
560
561- Attempted a fix to make the OpenSSL support in the socket module
562 work again with pre-0.9.5 versions of OpenSSL.
563
564Tests
565
566- Added a test case for asynchat and asyncore.
567
568- Removed coupling between tests where one test failing could break
569 another.
570
571Tools
572
573- Ping added an interactive help browser to pydoc, fixed some nits
574 in the rest of the pydoc code, and added some features to his
575 inspect module.
576
577- An updated python-mode.el version 4.1 which integrates Ken
578 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
579 much nicer in XEmacs and Emacs. When stepping through your program
580 with pdb, in either the shell window or the *Python* window, the
581 source file and line will be tracked by an arrow. Very cool!
582
583- IDLE: syntax warnings in interactive mode are changed into errors.
584
585- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +0000586 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +0000587
588- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000589
Barry Warsaw11e89c72001-04-11 20:37:57 +0000590
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000591What's New in Python 2.1 beta 2?
592================================
593
Guido van Rossum053ae352001-03-22 14:17:21 +0000594(Unlisted are many fixed bugs, more documentation, etc.)
595
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000596Core language, builtins, and interpreter
597
Guido van Rossum053ae352001-03-22 14:17:21 +0000598- The nested scopes work (enabled by "from __future__ import
599 nested_scopes") is completed; in particular, the future now extends
600 into code executed through exec, eval() and execfile(), and into the
601 interactive interpreter.
602
603- When calling a base class method (e.g. BaseClass.__init__(self)),
604 this is now allowed even if self is not strictly spoken a class
605 instance (e.g. when using metaclasses or the Don Beaudry hook).
606
607- Slice objects are now comparable but not hashable; this prevents
608 dict[:] from being accepted but meaningless.
609
610- Complex division is now calculated using less braindead algorithms.
611 This doesn't change semantics except it's more likely to give useful
612 results in extreme cases. Complex repr() now uses full precision
613 like float repr().
614
615- sgmllib.py now calls handle_decl() for simple <!...> declarations.
616
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000617- It is illegal to assign to the name __debug__, which is set when the
618 interpreter starts. It is effectively a compile-time constant.
619
620- A warning will be issued if a global statement for a variable
621 follows a use or assignment of that variable.
622
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000623Standard library
624
Guido van Rossum053ae352001-03-22 14:17:21 +0000625- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
626 inspired by JUnit), is now part of the standard library. You now
627 have a choice of two testing frameworks: unittest requires you to
628 write testcases as separate code, doctest gathers them from
629 docstrings. Both approaches have their advantages and
630 disadvantages.
631
632- A new module Tix was added, which wraps the Tix extension library
633 for Tk. With that module, it is not necessary to statically link
634 Tix with _tkinter, since Tix will be loaded with Tcl's "package
635 require" command. See Demo/tix/.
636
637- tzparse.py is now obsolete.
638
639- In gzip.py, the seek() and tell() methods are removed -- they were
640 non-functional anyway, and it's better if callers can test for their
641 existence with hasattr().
642
643Python/C API
644
645- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
646 that's already in the dictionary during a PyDict_Next() iteration.
647 This used to fail occasionally when a dictionary resize operation
648 could be triggered that would rehash all the keys. All other
649 modifications to the dictionary are still off-limits during a
650 PyDict_Next() iteration!
651
652- New extended APIs related to passing compiler variables around.
653
654- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
655 implement isinstance() and issubclass().
656
657- Py_BuildValue() now has a "D" conversion to create a Python complex
658 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000659
Fred Drake4e262a92001-03-22 18:26:47 +0000660- Extensions types which support weak references must now set the
661 field allocated for the weak reference machinery to NULL themselves;
662 this is done to avoid the cost of checking each object for having a
663 weakly referencable type in PyObject_INIT(), since most types are
664 not weakly referencable.
665
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000666- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
667 free variables and cell variables to and from the frame's f_locals.
668
669- Variants of several functions defined in pythonrun.h have been added
670 to support the nested_scopes future statement. The variants all end
671 in Flags and take an extra argument, a PyCompilerFlags *; examples:
672 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
673 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +0000674 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000675
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000676Distutils
677
678- the sdist command now writes a PKG-INFO file, as described in PEP 241,
679 into the release tree.
680
Tim Peters0e57abf2001-05-02 07:39:38 +0000681- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000682 (an uninstaller, more customization of the installer's display)
683
684- from Jack Jansen: added Mac-specific code to generate a dialog for
685 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +0000686 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000687 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +0000688
689- added 'platforms' and 'keywords' to the set of metadata that can be
690 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000691
692- applied patches from Jason Tishler to make the compiler class work with
693 Cygwin.
694
695
Tim Peters2fe289a2001-03-01 22:19:38 +0000696What's New in Python 2.1 beta 1?
697================================
Tim Petersd66595f2001-02-04 03:09:53 +0000698
699Core language, builtins, and interpreter
700
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000701- Following an outcry from the community about the amount of code
702 broken by the nested scopes feature introduced in 2.1a2, we decided
703 to make this feature optional, and to wait until Python 2.2 (or at
704 least 6 months) to make it standard. The option can be enabled on a
705 per-module basis by adding "from __future__ import nested_scopes" at
706 the beginning of a module (before any other statements, but after
707 comments and an optional docstring). See PEP 236 (Back to the
708 __future__) for a description of the __future__ statement. PEP 227
709 (Statically Nested Scopes) has been updated to reflect this change,
710 and to clarify the semantics in a number of endcases.
711
712- The nested scopes code, when enabled, has been hardened, and most
713 bugs and memory leaks in it have been fixed.
714
715- Compile-time warnings are now generated for a number of conditions
716 that will break or change in meaning when nested scopes are enabled:
717
718 - Using "from...import *" or "exec" without in-clause in a function
719 scope that also defines a lambda or nested function with one or
720 more free (non-local) variables. The presence of the import* or
721 bare exec makes it impossible for the compiler to determine the
722 exact set of local variables in the outer scope, which makes it
723 impossible to determine the bindings for free variables in the
724 inner scope. To avoid the warning about import *, change it into
725 an import of explicitly name object, or move the import* statement
726 to the global scope; to avoid the warning about bare exec, use
727 exec...in... (a good idea anyway -- there's a possibility that
728 bare exec will be deprecated in the future).
729
730 - Use of a global variable in a nested scope with the same name as a
731 local variable in a surrounding scope. This will change in
732 meaning with nested scopes: the name in the inner scope will
733 reference the variable in the outer scope rather than the global
734 of the same name. To avoid the warning, either rename the outer
735 variable, or use a global statement in the inner function.
736
Neil Schemenauera35c6882001-02-27 04:45:05 +0000737- An optional object allocator has been included. This allocator is
738 optimized for Python objects and should be faster and use less memory
739 than the standard system allocator. It is not enabled by default
740 because of possible thread safety problems. The allocator is only
741 protected by the Python interpreter lock and it is possible that some
742 extension modules require a thread safe allocator. The object
743 allocator can be enabled by providing the "--with-pymalloc" option to
744 configure.
745
Tim Petersd66595f2001-02-04 03:09:53 +0000746Standard library
747
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000748- pyexpat now detects the expat version if expat.h defines it. A
749 number of additional handlers are provided, which are only available
750 since expat 1.95. In addition, the methods SetParamEntityParsing and
751 GetInputContext of Parser objects are available with 1.95.x
752 only. Parser objects now provide the ordered_attributes and
753 specified_attributes attributes. A new module expat.model was added,
754 which offers a number of additional constants if 1.95.x is used.
755
756- xml.dom offers the new functions registerDOMImplementation and
757 getDOMImplementation.
758
759- xml.dom.minidom offers a toprettyxml method. A number of DOM
760 conformance issues have been resolved. In particular, Element now
761 has an hasAttributes method, and the handling of namespaces was
762 improved.
763
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000764- Ka-Ping Yee contributed two new modules: inspect.py, a module for
765 getting information about live Python code, and pydoc.py, a module
766 for interactively converting docstrings to HTML or text.
767 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000768 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000769 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
770 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000771
Tim Peters1eff7962001-03-01 02:31:33 +0000772- New library module difflib.py, primarily packaging the SequenceMatcher
773 class at the heart of the popular ndiff.py file-comparison tool.
774
775- doctest.py (a framework for verifying Python code examples in docstrings)
776 is now part of the std library.
777
Tim Petersd66595f2001-02-04 03:09:53 +0000778Windows changes
779
Guido van Rossume3955a82001-03-02 14:05:59 +0000780- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
781 small GUI that lets you browse the module docstrings using your
782 default web browser.
783
Tim Peters1eff7962001-03-01 02:31:33 +0000784- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
785 Platforms) is implemented. See
786
787 http://python.sourceforge.net/peps/pep-0235.html
788
789 for full details, especially the "Current Lower-Left Semantics" section.
790 The new Windows import rules are simpler than before:
791
792 A. If the PYTHONCASEOK environment variable exists, same as
793 before: silently accept the first case-insensitive match of any
794 kind; raise ImportError if none found.
795
796 B. Else search sys.path for the first case-sensitive match; raise
797 ImportError if none found.
798
799 The same rules have been implented on other platforms with case-
800 insensitive but case-preserving filesystems too (including Cygwin, and
801 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000802
Tim Peters25a9ce32001-02-19 07:06:36 +0000803- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
804 what it's supposed to do (and does do under NT and 2000) via direct
805 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000806 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000807 all Win9x systems before.
808
Tim Peters1eff7962001-03-01 02:31:33 +0000809- Build: Subproject _test (effectively) renamed to _testcapi.
810
Tim Peters2fe289a2001-03-01 22:19:38 +0000811New platforms
812
813- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
814 Thanks to Steven Majewski!
815
816- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
817 Tishler!
818
Guido van Rossum9089b272001-03-02 06:49:50 +0000819- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
820 Schwertberger! See RISCOS/README for more information -- it seems
821 that because of the bizarre filename conventions on RISCOS, no port
822 to that platform is easy. Note that the new variable os.endsep is
823 silently supported in order to make life easier on this platform,
824 but we don't advertise it because it's not worth for most folks to
825 care about RISCOS portability.
826
Tim Peters25a9ce32001-02-19 07:06:36 +0000827
Tim Petersd7b5e882001-01-25 03:36:26 +0000828What's New in Python 2.1 alpha 2?
829=================================
Tim Peters40ead762001-01-27 05:35:26 +0000830
Tim Petersd7b5e882001-01-25 03:36:26 +0000831Core language, builtins, and interpreter
832
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000833- Scopes nest. If a name is used in a function or class, but is not
834 local, the definition in the nearest enclosing function scope will
835 be used. One consequence of this change is that lambda statements
836 could reference variables in the namespaces where the lambda is
837 defined. In some unusual cases, this change will break code.
838
839 In all previous version of Python, names were resolved in exactly
840 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000841 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000842 function A is defined within a function B, the names bound in B are
843 not visible in A. The new rules make names bound in B visible in A,
844 unless A contains a name binding that hides the binding in B.
845
846 Section 4.1 of the reference manual describes the new scoping rules
847 in detail. The test script in Lib/test/test_scope.py demonstrates
848 some of the effects of the change.
849
850 The new rules will cause existing code to break if it defines nested
851 functions where an outer function has local variables with the same
852 name as globals or builtins used by the inner function. Example:
853
854 def munge(str):
855 def helper(x):
856 return str(x)
857 if type(str) != type(''):
858 str = helper(str)
859 return str.strip()
860
861 Under the old rules, the name str in helper() is bound to the
862 builtin function str(). Under the new rules, it will be bound to
863 the argument named str and an error will occur when helper() is
864 called.
865
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000866- The compiler will report a SyntaxError if "from ... import *" occurs
867 in a function or class scope. The language reference has documented
868 that this case is illegal, but the compiler never checked for it.
869 The recent introduction of nested scope makes the meaning of this
870 form of name binding ambiguous. In a future release, the compiler
871 may allow this form when there is no possibility of ambiguity.
872
Tim Peters40ead762001-01-27 05:35:26 +0000873- repr(string) is easier to read, now using hex escapes instead of octal,
874 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
875
876 >>> "\texample \r\n" + chr(0) + chr(255)
877 '\texample \r\n\x00\xff' # in 2.1
878 '\011example \015\012\000\377' # in 2.0
879
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000880- Functions are now compared and hashed by identity, not by value, since
881 the func_code attribute is writable.
882
Fred Drakefb9d7122001-02-01 20:00:40 +0000883- Weak references (PEP 205) have been added. This involves a few
884 changes in the core, an extension module (_weakref), and a Python
885 module (weakref). The weakref module is the public interface. It
886 includes support for "explicit" weak references, proxy objects, and
887 mappings with weakly held values.
888
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000889- A 'continue' statement can now appear in a try block within the body
890 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000891 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000892
Tim Petersd7b5e882001-01-25 03:36:26 +0000893Standard library
894
Barry Warsaw30dbd142001-01-31 22:14:01 +0000895- mailbox.py now has a new class, PortableUnixMailbox which is
896 identical to UnixMailbox but uses a more portable scheme for
897 determining From_ separators. Also, the constructors for all the
898 classes in this module have a new optional `factory' argument, which
899 is a callable used when new message classes must be instantiated by
900 the next() method.
901
Tim Petersd7b5e882001-01-25 03:36:26 +0000902- random.py is now self-contained, and offers all the functionality of
903 the now-deprecated whrandom.py. See the docs for details. random.py
904 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000905 and restoring the internal state of the generator; and jumpahead(n),
906 for quickly forcing the internal state to be the same as if n calls to
907 random() had been made. The latter is particularly useful for multi-
908 threaded programs, creating one instance of the random.Random() class for
909 each thread, then using .jumpahead() to force each instance to use a
910 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000911
Tim Peters0de88fc2001-02-01 04:59:18 +0000912- random.py's seed() function is new. For bit-for-bit compatibility with
913 prior releases, use the whseed function instead. The new seed function
914 addresses two problems: (1) The old function couldn't produce more than
915 about 2**24 distinct internal states; the new one about 2**45 (the best
916 that can be done in the Wichmann-Hill generator). (2) The old function
917 sometimes produced identical internal states when passed distinct
918 integers, and there was no simple way to predict when that would happen;
919 the new one guarantees to produce distinct internal states for all
920 arguments in [0, 27814431486576L).
921
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000922- The socket module now supports raw packets on Linux. The socket
923 family is AF_PACKET.
924
Tim Peters9ea17ac2001-02-02 05:57:15 +0000925- test_capi.py is a start at running tests of the Python C API. The tests
926 are implemented by the new Modules/_testmodule.c.
927
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000928- A new extension module, _symtable, provides provisional access to the
929 internal symbol table used by the Python compiler. A higher-level
930 interface will be added on top of _symtable in a future release.
931
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000932- Removed the obsolete soundex module.
933
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000934- xml.dom.minidom now uses the standard DOM exceptions. Node supports
935 the isSameNode method; NamedNodeMap the get method.
936
937- xml.sax.expatreader supports the lexical handler property; it
938 generates comment, startCDATA, and endCDATA events.
939
Tim Petersee826f82001-01-31 19:39:44 +0000940Windows changes
941
942- Build procedure: the zlib project is built in a different way that
943 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000944 the zlib binary used. See PCbuild\readme.txt for details. Your old
945 zlib-related directories can be deleted; you'll need to download fresh
946 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000947
Tim Peters9ea17ac2001-02-02 05:57:15 +0000948- Build: New subproject _test for the benefit of test_capi.py (see above).
949
Tim Petersb16c56f2001-02-02 21:24:51 +0000950- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
951 interface to some Python compiler internals).
952
953- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000954 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000955
Tim Petersa3a3a032000-11-30 05:22:44 +0000956What's New in Python 2.1 alpha 1?
957=================================
958
959Core language, builtins, and interpreter
960
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000961- There is a new Unicode companion to the PyObject_Str() API
962 called PyObject_Unicode(). It behaves in the same way as the
963 former, but assures that the returned value is an Unicode object
964 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000965
Guido van Rossumf98eda02001-01-17 15:54:45 +0000966- The comparison operators support "rich comparison overloading" (PEP
967 207). C extension types can provide a rich comparison function in
968 the new tp_richcompare slot in the type object. The cmp() function
969 and the C function PyObject_Compare() first try the new rich
970 comparison operators before trying the old 3-way comparison. There
971 is also a new C API PyObject_RichCompare() (which also falls back on
972 the old 3-way comparison, but does not constrain the outcome of the
973 rich comparison to a Boolean result).
974
975 The rich comparison function takes two objects (at least one of
976 which is guaranteed to have the type that provided the function) and
977 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
978 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
979 object, which may be NotImplemented (in which case the tp_compare
980 slot function is used as a fallback, if defined).
981
982 Classes can overload individual comparison operators by defining one
983 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000984 __ge__. There are no explicit "reflected argument" versions of
985 these; instead, __lt__ and __gt__ are each other's reflection,
986 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
987 reflection (similar at the C level). No other implications are
988 made; in particular, Python does not assume that == is the Boolean
989 inverse of !=, or that < is the Boolean inverse of >=. This makes
990 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000991
992 Classes or types that want to implement (in)equality tests but not
993 the ordering operators (i.e. unordered types) should implement ==
994 and !=, and raise an error for the ordering operators.
995
Guido van Rossuma88479f2001-01-18 14:28:08 +0000996 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +0000997 Boolean; e.g. a matrix type might want to return a matrix of bits
998 for A < B, giving elementwise comparisons. Such types should ensure
999 that any interpretation of their value in a Boolean context raises
1000 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
1001 at the C level) to always raise an exception.
1002
Guido van Rossuma88479f2001-01-18 14:28:08 +00001003- Complex numbers use rich comparisons to define == and != but raise
1004 an exception for <, <=, > and >=. Unfortunately, this also means
1005 that cmp() of two complex numbers raises an exception when the two
1006 numbers differ. Since it is not mathematically meaningful to compare
1007 complex numbers except for equality, I hope that this doesn't break
1008 too much code.
1009
Tim Peters3389f192001-02-18 08:48:49 +00001010- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +00001011 not defined by the language, other than that it's arbitrary but
1012 consistent (see the Reference Manual). An implementation detail changed
1013 in 2.1a1 such that None now compares less than any other object. Code
1014 relying on this new behavior (like code that relied on the previous
1015 behavior) does so at its own risk.
1016
Barry Warsaw573b5412001-01-15 20:43:18 +00001017- Functions and methods now support getting and setting arbitrarily
1018 named attributes (PEP 232). Functions have a new __dict__
1019 (a.k.a. func_dict) which hold the function attributes. Methods get
1020 and set attributes on their underlying im_func. It is a TypeError
1021 to set an attribute on a bound method.
1022
Guido van Rossum051e3352001-01-15 19:11:10 +00001023- The xrange() object implementation has been improved so that
1024 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1025 limitation that in this case len(xrange(sys.maxint)) can't be
1026 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1027 work fine as long as the index i doesn't actually reach 2**31.
1028 (Python uses regular ints for sequence and string indices; fixing
1029 that is much more work.)
1030
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001031- Two changes to from...import:
1032
Guido van Rossumba381232001-02-03 15:06:40 +00001033 1) "from M import X" now works even if (after loading module M)
1034 sys.modules['M'] is not a real module; it's basically a getattr()
1035 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001036
1037 2) "from M import *" now looks for M.__all__ to decide which names to
1038 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1039 filters out names starting with '_' as before. Whether or not
1040 __all__ exists, there's no restriction on the type of M.
1041
Guido van Rossumf61f1662001-01-10 20:13:55 +00001042- File objects have a new method, xreadlines(). This is the fastest
1043 way to iterate over all lines in a file:
1044
1045 for line in file.xreadlines():
1046 ...do something to line...
1047
1048 See the xreadlines module (mentioned below) for how to do this for
1049 other file-like objects.
1050
1051- Even if you don't use file.xreadlines(), you may expect a speedup on
1052 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001053 quite a bit in platform-specific ways: on systems (like Linux) that
1054 support flockfile(), getc_unlocked(), and funlockfile(), those are
1055 used by default. On systems (like Windows) without getc_unlocked(),
1056 a complicated (but still thread-safe) method using fgets() is used by
1057 default.
1058
Tim Petersd52269b2001-01-25 06:23:18 +00001059 You can force use of the fgets() method by #define'ing
1060 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001061 getc_unlocked()).
1062
Tim Petersd52269b2001-01-25 06:23:18 +00001063 You can force fgets() not to be used by #define'ing
1064 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001065 test_bufio.py fails -- and let us know if it does!).
1066
1067- In addition, the fileinput module, while still slower than the other
1068 methods on most platforms, has been sped up too, by using
1069 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001070
1071- Support for run-time warnings has been added, including a new
1072 command line option (-W) to specify the disposition of warnings.
1073 See the description of the warnings module below.
1074
1075- Extensive changes have been made to the coercion code. This mostly
1076 affects extension modules (which can now implement mixed-type
1077 numerical operators without having to use coercion), but
1078 occasionally, in boundary cases the coercion semantics have changed
1079 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001080 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001081 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001082 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001083
Guido van Rossumf98eda02001-01-17 15:54:45 +00001084- In connection with the coercion changes, a new built-in singleton
1085 object, NotImplemented is defined. This can be returned for
1086 operations that wish to indicate they are not implemented for a
1087 particular combination of arguments. From C, this is
1088 Py_NotImplemented.
1089
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001090- The interpreter accepts now bytecode files on the command line even
1091 if they do not have a .pyc or .pyo extension. On Linux, after executing
1092
Martin v. Löwise214baa2001-02-04 22:37:56 +00001093import imp,sys,string
1094magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1095reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1096open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001097
1098 any byte code file can be used as an executable (i.e. as an argument
1099 to execve(2)).
1100
Tim Peters9940b802000-12-01 07:59:35 +00001101- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001102 character. In 1.6 and earlier, they never produced a sign,
1103 and raised an error if the value of the long was too large
1104 to fit in a Python int. In 2.0, they produced a sign if and
1105 only if too large to fit in an int. This was inconsistent
1106 across platforms (because the size of an int varies across
1107 platforms), and inconsistent with hex() and oct(). Example:
1108
1109 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001110 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001111 'ffffffbe' # in 2.0 and before, on 32-bit machines
1112 >>> hex(-0x42L)
1113 '-0x42L' # in all versions of Python
1114
Tim Peters9940b802000-12-01 07:59:35 +00001115 The behavior of %d formats for negative Python longs remains
1116 the same as in 2.0 (although in 1.6 and before, they raised
1117 an error if the long didn't fit in a Python int).
1118
1119 %u formats don't make sense for Python longs, but are allowed
1120 and treated the same as %d in 2.1. In 2.0, a negative long
1121 formatted via %u produced a sign if and only if too large to
1122 fit in an int. In 1.6 and earlier, a negative long formatted
1123 via %u raised an error if it was too big to fit in an int.
1124
Guido van Rossum3661d392000-12-12 22:10:31 +00001125- Dictionary objects have an odd new method, popitem(). This removes
1126 an arbitrary item from the dictionary and returns it (in the form of
1127 a (key, value) pair). This can be useful for algorithms that use a
1128 dictionary as a bag of "to do" items and repeatedly need to pick one
1129 item. Such algorithms normally end up running in quadratic time;
1130 using popitem() they can usually be made to run in linear time.
1131
Tim Peters36cdad12000-12-29 02:06:45 +00001132Standard library
1133
Thomas Woutersfe385252001-01-19 23:16:56 +00001134- In the time module, the time argument to the functions strftime,
1135 localtime, gmtime, asctime and ctime is now optional, defaulting to
1136 the current time (in the local timezone).
1137
Guido van Rossumda91f222001-01-15 16:36:08 +00001138- The ftplib module now defaults to passive mode, which is deemed a
1139 more useful default given that clients are often inside firewalls
1140 these days. Note that this could break if ftplib is used to connect
1141 to a *server* that is inside a firewall, from outside; this is
1142 expected to be a very rare situation. To fix that, you can call
1143 ftp.set_pasv(0).
1144
Martin v. Löwis10a27872001-01-13 09:54:41 +00001145- The module site now treats .pth files not only for path configuration,
1146 but also supports extensions to the initialization code: Lines starting
1147 with import are executed.
1148
Guido van Rossumf61f1662001-01-10 20:13:55 +00001149- There's a new module, warnings, which implements a mechanism for
1150 issuing and filtering warnings. There are some new built-in
1151 exceptions that serve as warning categories, and a new command line
1152 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1153 turns warnings into errors). warnings.warn(message[, category])
1154 issues a warning message; this can also be called from C as
1155 PyErr_Warn(category, message).
1156
1157- A new module xreadlines was added. This exports a single factory
1158 function, xreadlines(). The intention is that this code is the
1159 absolutely fastest way to iterate over all lines in an open
1160 file(-like) object:
1161
1162 import xreadlines
1163 for line in xreadlines.xreadlines(file):
1164 ...do something to line...
1165
1166 This is equivalent to the previous the speed record holder using
1167 file.readlines(sizehint). Note that if file is a real file object
1168 (as opposed to a file-like object), this is equivalent:
1169
1170 for line in file.xreadlines():
1171 ...do something to line...
1172
Tim Peters36cdad12000-12-29 02:06:45 +00001173- The bisect module has new functions bisect_left, insort_left,
1174 bisect_right and insort_right. The old names bisect and insort
1175 are now aliases for bisect_right and insort_right. XXX_right
1176 and XXX_left methods differ in what happens when the new element
1177 compares equal to one or more elements already in the list: the
1178 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001179 right. Code that doesn't care where equal elements end up should
1180 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001181
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001182- The new curses.panel module wraps the panel library that forms part
1183 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1184
Guido van Rossumf61f1662001-01-10 20:13:55 +00001185- The SocketServer module now sets the allow_reuse_address flag by
1186 default in the TCPServer class.
1187
1188- A new function, sys._getframe(), returns the stack frame pointer of
1189 the caller. This is intended only as a building block for
1190 higher-level mechanisms such as string interpolation.
1191
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001192- The pyexpat module supports a number of new handlers, which are
1193 available only in expat 1.2. If invocation of a callback fails, it
1194 will report an additional frame in the traceback. Parser objects
1195 participate now in garbage collection. If expat reports an unknown
1196 encoding, pyexpat will try to use a Python codec; that works only
1197 for single-byte charsets. The parser type objects is exposed as
1198 XMLParserObject.
1199
1200- xml.dom now offers standard definitions for symbolic node type and
1201 exception code constants, and a hierarchy of DOM exceptions. minidom
1202 was adjusted to use them.
1203
1204- The conformance of xml.dom.minidom to the DOM specification was
1205 improved. It detects a number of additional error cases; the
1206 previous/next relationship works even when the tree is modified;
1207 Node supports the normalize() method; NamedNodeMap, DocumentType and
1208 DOMImplementation classes were added; Element supports the
1209 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1210 method.
1211
Guido van Rossumf61f1662001-01-10 20:13:55 +00001212Build issues
1213
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001214- For Unix (and Unix-compatible) builds, configuration and building of
1215 extension modules is now greatly automated. Rather than having to
1216 edit the Modules/Setup file to indicate which modules should be
1217 built and where their include files and libraries are, a
1218 distutils-based setup.py script now takes care of building most
1219 extension modules. All extension modules built this way are built
1220 as shared libraries. Only a few modules that must be linked
1221 statically are still listed in the Setup file; you won't need to
1222 edit their configuration.
1223
1224- Python should now build out of the box on Cygwin. If it doesn't,
1225 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001226
1227- Python now always uses its own (renamed) implementation of getopt()
1228 -- there's too much variation among C library getopt()
1229 implementations.
1230
1231- C++ compilers are better supported; the CXX macro is always set to a
1232 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001233
Tim Petersd92dfe02000-12-12 01:18:41 +00001234Windows changes
1235
1236- select module: By default under Windows, a select() call
1237 can specify no more than 64 sockets. Python now boosts
1238 this Microsoft default to 512. If you need even more than
1239 that, see the MS docs (you'll need to #define FD_SETSIZE
1240 and recompile Python from source).
1241
Guido van Rossumf61f1662001-01-10 20:13:55 +00001242- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1243 subdirectory is no more!
1244
Tim Petersa3a3a032000-11-30 05:22:44 +00001245
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001246What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001247=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001248
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001249Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001250changes are in the file HISTORY. If you are making the jump directly
1251from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1252HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001253
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001254Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1255the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1256http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001257
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001258--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001259
1260======================================================================
1261
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001262What's new in 2.0 (since release candidate 1)?
1263==============================================
1264
1265Standard library
1266
1267- The copy_reg module was modified to clarify its intended use: to
1268 register pickle support for extension types, not for classes.
1269 pickle() will raise a TypeError if it is passed a class.
1270
1271- Fixed a bug in gettext's "normalize and expand" code that prevented
1272 it from finding an existing .mo file.
1273
1274- Restored support for HTTP/0.9 servers in httplib.
1275
Tim Peters989b7b92000-10-16 20:24:53 +00001276- The math module was changed to stop raising OverflowError in case of
1277 underflow, and return 0 instead in underflow cases. Whether Python
1278 used to raise OverflowError in case of underflow was platform-
1279 dependent (it did when the platform math library set errno to ERANGE
1280 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001281
1282- Fixed a bug in StringIO that occurred when the file position was not
1283 at the end of the file and write() was called with enough data to
1284 extend past the end of the file.
1285
1286- Fixed a bug that caused Tkinter error messages to get lost on
1287 Windows. The bug was fixed by replacing direct use of
1288 interp->result with Tcl_GetStringResult(interp).
1289
1290- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1291 redirect response.
1292
1293- Several changes were made to distutils: Some debugging code was
1294 removed from util. Fixed the installer used when an external zip
1295 program (like WinZip) is not found; the source code for this
1296 installer is in Misc/distutils. check_lib() was modified to behave
1297 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1298 test for whether installed modules are on sys.path was changed to
1299 use both normcase() and normpath().
1300
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001301- Several minor bugs were fixed in the xml package (the minidom,
1302 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001303
1304- The regression test driver (regrtest.py) behavior when invoked with
1305 -l changed: It now reports a count of objects that are recognized as
1306 garbage but not freed by the garbage collector.
1307
Tim Peters989b7b92000-10-16 20:24:53 +00001308- The regression test for the math module was changed to test
1309 exceptional behavior when the test is run in verbose mode. Python
1310 cannot yet guarantee consistent exception behavior across platforms,
1311 so the exception part of test_math is run only in verbose mode, and
1312 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001313
1314Internals
1315
1316- PyOS_CheckStack() has been disabled on Win64, where it caused
1317 test_sre to fail.
1318
1319Build issues
1320
1321- Changed compiler flags, so that gcc is always invoked with -Wall and
1322 -Wstrict-prototypes. Users compiling Python with GCC should see
1323 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001324 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001325 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001326
Tim Petersa3a3a032000-11-30 05:22:44 +00001327- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001328
1329Tools and other miscellany
1330
1331- The compiler in Tools/compiler was updated to support the new
1332 language features introduced in 2.0: extended print statement, list
1333 comprehensions, and augmented assignments. The new compiler should
1334 also be backwards compatible with Python 1.5.2; the compiler will
1335 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001336 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001337
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001338What's new in 2.0 release candidate 1 (since beta 2)?
1339=====================================================
1340
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001341What is release candidate 1?
1342
1343We believe that release candidate 1 will fix all known bugs that we
1344intend to fix for the 2.0 final release. This release should be a bit
1345more stable than the previous betas. We would like to see even more
1346widespread testing before the final release, so we are producing this
1347release candidate. The final release will be exactly the same unless
1348any show-stopping (or brown bag) bugs are found by testers of the
1349release candidate.
1350
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001351All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001352to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001353
1354Core language, builtins, and interpreter
1355
1356- A bug that caused crashes when __coerce__ was used with augmented
1357 assignment, e.g. +=, was fixed.
1358
1359- Raise ZeroDivisionError when raising zero to a negative number,
1360 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1361 power operator and the result of math.pow(0.0, -2.0) will vary by
1362 platform. On Linux, it raises a ValueError.
1363
1364- A bug in Unicode string interpolation was fixed that occasionally
1365 caused errors with formats including "%%". For example, the
1366 following expression "%% %s" % u"abc" no longer raises a TypeError.
1367
1368- Compilation of deeply nested expressions raises MemoryError instead
1369 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1370
1371- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1372 rendering them useless. They are now written in binary mode again.
1373
1374Standard library
1375
1376- Keyword arguments are now accepted for most pattern and match object
1377 methods in SRE, the standard regular expression engine.
1378
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001379- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001380 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001381
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001382- Several bugs in the Unicode handling and error handling in _tkinter
1383 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001384
1385- Fix memory management errors in Merge() and Tkapp_Call() routines.
1386
1387- Several changes were made to cStringIO to make it compatible with
1388 the file-like object interface and with StringIO. If operations are
1389 performed on a closed object, an exception is raised. The truncate
1390 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001391 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001392
1393- There were many changes made to the linuxaudiodev module and its
1394 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001395 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001396
1397 Note that this module is named poorly, because it should work
1398 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001399 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001400
1401 The module now raises exceptions when errors occur instead of
1402 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1403 audio) and defines a getptr() method that calls the
1404 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1405
1406- The library_version attribute, introduced in an earlier beta, was
1407 removed because it can not be supported with early versions of the C
1408 readline library, which provides no way to determine the version at
1409 compile-time.
1410
1411- The binascii module is now enabled on Win64.
1412
Tim Peters46446d62000-10-09 21:19:31 +00001413- tokenize.py no longer suffers "recursion depth" errors when parsing
1414 programs with very long string literals.
1415
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001416Internals
1417
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001418- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001419 which is called when the interpreter starts up to determine where
1420 the standard library is installed. These vulnerabilities affect all
1421 previous versions of Python and can be exploited by setting very
1422 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1423 setuid Python script, although use of the wrapper in
1424 Misc/setuid-prog.c will eliminate the vulnerability.
1425
1426- Fixed garbage collection bugs in instance creation that were
1427 triggered when errors occurred during initialization. The solution,
1428 applied in cPickle and in PyInstance_New(), is to call
1429 PyObject_GC_Init() after the initialization of the object's
1430 container attributes is complete.
1431
1432- pyexpat adds definitions of PyModule_AddStringConstant and
1433 PyModule_AddObject if the Python version is less than 2.0, which
1434 provides compatibility with PyXML on Python 1.5.2.
1435
1436- If the platform has a bogus definition for LONG_BIT (the number of
1437 bits in a long), an error will be reported at compile time.
1438
1439- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1440 collection crashes and possibly other, unreported crashes.
1441
1442- Fixed a memory leak in _PyUnicode_Fini().
1443
1444Build issues
1445
1446- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001447 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001448 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001449
1450- The mmap.PAGESIZE constant is now initialized using sysconf when
1451 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1452
1453- The md5 file should now compile on all platforms.
1454
1455- The select module now compiles on platforms that do not define
1456 POLLRDNORM and related constants.
1457
1458- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001459 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001460
Jeremy Hylton10921202000-10-09 18:34:12 +00001461- BeOS: A number of changes were made to the build and installation
1462 process. ar-fake now operates on a directory of object files.
1463 dl_export.h is gone, and its macros now appear on the mwcc command
1464 line during build on PPC BeOS.
1465
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001466- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001467 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001468
1469- Cygwin: Support for shared libraries, Tkinter, and sockets.
1470
1471- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1472
1473Tools and other miscellany
1474
1475- Removed debugging prints from main used with freeze.
1476
Tim Peters46446d62000-10-09 21:19:31 +00001477- IDLE auto-indent no longer crashes when it encounters Unicode
1478 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001479
1480What's new in 2.0 beta 2 (since beta 1)?
1481========================================
1482
1483Core language, builtins, and interpreter
1484
Tim Peters482c0212000-09-26 06:33:09 +00001485- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001486 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001487
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001488- Add -h and -V command line options to print the usage message and
1489 Python version number and exit immediately.
1490
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001491- eval() and exec accept Unicode objects as code parameters.
1492
1493- getattr() and setattr() now also accept Unicode objects for the
1494 attribute name, which are converted to strings using the default
1495 encoding before lookup.
1496
1497- Multiplication on string and Unicode now does proper bounds
1498 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1499 string is too long."
1500
1501- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001502 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001503
Jeremy Hylton1b618592000-09-26 05:32:36 +00001504
1505Standard library and extensions
1506
Guido van Rossum5b08f132001-04-16 02:05:23 +00001507- socket module: the OpenSSL code now adds support for RAND_status()
1508 and EGD (Entropy Gathering Device).
1509
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001510- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001511 argument checking; it still takes no arguments.
1512
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001513- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001514
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001515- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001516
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001517- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001518
1519- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001520 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001521
1522- copy: Copy Unicode objects atomically.
1523
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001524- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001525
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001526- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001527
Fred Drake67233bc2000-09-26 16:40:27 +00001528- dbm: Add get() and setdefault() methods to dbm object. Add constant
1529 `library' to module that names the library used. Added doc strings
1530 and method names to error messages. Uses configure to determine
1531 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1532 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001533
1534- distutils: Update to version 0.9.3.
1535
1536- dl: Add several dl.RTLD_ constants.
1537
1538- fpectl: Now supported on FreeBSD.
1539
1540- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1541 found by the collector will be saved in gc.garbage. This is useful
1542 for debugging a program that creates reference cycles.
1543
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001544- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001545 of HTTP class. Do not close socket on zero-length response. Do not
1546 crash when server sends invalid content-length header.
1547
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001548- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001549
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001550- marshal: When reading a short, sign-extend on platforms where shorts
1551 are bigger than 16 bits. When reading a long, repair the unportable
1552 sign extension that was being done for 64-bit machines. (It assumed
1553 that signed right shift sign-extends.)
1554
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001555- operator: Add contains(), invert(), __invert__() as aliases for
1556 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001557
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001558- os: Add support for popen2() and popen3() on all platforms where
1559 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001560
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001561- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001562 clicking on a file in Explorer (or passing the file name to the
1563 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001564
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001565- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001566 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001567
1568- pickle: Now raises ValueError when an invalid pickle that contains
1569 a non-string repr where a string repr was expected. This behavior
1570 matches cPickle.
1571
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001572- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001573
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001574- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001575
1576- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001577 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001578 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001579
1580- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001581 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001582
1583- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001584 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001585 few cycles during startup since the first call to
1586 setdefaultencoding() will initialize the codec registry and the
1587 encodings package.
1588
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001589- socket: Support for size hint in readlines() method of object returned
1590 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001591
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001592- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001593 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001594 is followed by whitespace.
1595
Tim Petersa3a3a032000-11-30 05:22:44 +00001596- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001597
1598- struct: Check ranges for bytes and shorts.
1599
1600- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001601 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001602
1603- Tkinter: Image objects are now guaranteed to have unique ids. Set
1604 event.delta to zero if Tk version doesn't support mousewheel.
1605 Removed some debugging prints.
1606
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001607- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001608
Fred Drake67233bc2000-09-26 16:40:27 +00001609- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001610 which works around a bug in Norton AntiVirus 2000 that leads directly
1611 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001612
1613- xml: New version detection code allows PyXML to override standard
1614 XML package if PyXML version is greater than 0.6.1.
1615
Fred Drake64bb3802000-09-26 16:21:35 +00001616- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1617 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1618 tree only for nodes which are sufficiently interesting to a specific
1619 application. Does not provide the HTML-specific extensions. Still
1620 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001621
Fred Drake64bb3802000-09-26 16:21:35 +00001622- xml.sax: SAX 2 support for Python, including all the handler
1623 interfaces needed to process XML 1.0 compliant XML. Some
1624 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001625
Fred Drake64bb3802000-09-26 16:21:35 +00001626- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1627 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001628
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001629
Jeremy Hylton1b618592000-09-26 05:32:36 +00001630C API
1631
1632- Add three new convenience functions for module initialization --
1633 PyModule_AddObject(), PyModule_AddIntConstant(), and
1634 PyModule_AddStringConstant().
1635
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001636- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001637 removed and add #error to Python.h if NULL isn't defined after
1638 #include of stdio.h.
1639
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001640- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001641 backwards compatibility (at the source level) with old extensions.
1642
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001643- A wrapper API was added for signal() and sigaction(). Instead of
1644 either function, always use PyOS_getsig() to get a signal handler
1645 and PyOS_setsig() to set one. A new convenience typedef
1646 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001647
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001648- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001649 internal data buffer and size of a string object -- or the default
1650 encoded version of a Unicode object.
1651
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001652- PyString_Size() and PyString_AsString() accept Unicode objects.
1653
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001654- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001655 exists). INT_MAX and LONG_MAX will always be defined, even if
1656 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001657
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001658- PyFloat_FromString takes a second argument, pend, that was
1659 effectively useless. It is now officially useless but preserved for
1660 backwards compatibility. If the pend argument is not NULL, *pend is
1661 set to NULL.
1662
1663- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1664 for the attribute name. See note on getattr() above.
1665
1666- A few bug fixes to argument processing for Unicode.
1667 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1668 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1669 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001670 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001671
1672- Py_BuildValue accepts B format (for bgen-generated code).
1673
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001674
Jeremy Hylton1b618592000-09-26 05:32:36 +00001675Internals
1676
1677- On Unix, fix code for finding Python installation directory so that
1678 it works when argv[0] is a relative path.
1679
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001680- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001681 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001682 rather than by generating a copy of the object.
1683
Tim Peters482c0212000-09-26 06:33:09 +00001684- Several of the internal Unicode tables are much smaller now, and
1685 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001686
Jeremy Hylton97693b02000-09-26 17:42:51 +00001687- In the garbage collector: Fixed bug in collection of tuples. Fixed
1688 bug that caused some instances to be removed from the container set
1689 while they were still live. Fixed parsing in gc.set_debug() for
1690 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001691
1692- Fixed refcount problem in instance deallocation that only occurred
1693 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1694
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001695- On Windows, getpythonregpath is now protected against null data in
1696 registry key.
1697
1698- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001699 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001700
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001701
Jeremy Hylton1b618592000-09-26 05:32:36 +00001702Build and platform-specific issues
1703
1704- Better support of GNU Pth via --with-pth configure option.
1705
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001706- Python/C API now properly exposed to dynamically-loaded extension
1707 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001708
1709- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1710 Don't define MS_SYNC to be zero when it is undefined. Added missing
1711 prototypes in posixmodule.c.
1712
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001713- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001714 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001715
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001716- Fix largefile support on older NetBSD systems and OpenBSD by adding
1717 define for TELL64.
1718
1719
1720Tools and other miscellany
1721
1722- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1723
1724- freeze: The modulefinder now works with 2.0 opcodes.
1725
Tim Petersa3a3a032000-11-30 05:22:44 +00001726- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001727 Move hackery of sys.argv until after the Tk instance has been
1728 created, which allows the application-specific Tkinter
1729 initialization to be executed if present; also pass an explicit
1730 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001731
Jeremy Hylton1b618592000-09-26 05:32:36 +00001732
1733What's new in 2.0 beta 1?
1734=========================
1735
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001736Source Incompatibilities
1737------------------------
1738
1739None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1740such as single-argument append(), connect() and bind(), and changes to
1741str(long) and repr(float).
1742
1743
1744Binary Incompatibilities
1745------------------------
1746
1747- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1748with Python 2.0; these extensions will have to be rebuilt for Python
17492.0.
1750
1751- On Windows, attempting to import a third party extension built for
1752Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1753can do about this. Check your PYTHONPATH environment variable!
1754
1755- Python bytecode files (*.pyc and *.pyo) are not compatible between
1756releases.
1757
1758
1759Overview of Changes Since 1.6
1760-----------------------------
1761
1762There are many new modules (including brand new XML support through
1763the xml package, and i18n support through the gettext module); a list
1764of all new modules is included below. Lots of bugs have been fixed.
1765
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001766The process for making major new changes to the language has changed
1767since Python 1.6. Enhancements must now be documented by a Python
1768Enhancement Proposal (PEP) before they can be accepted.
1769
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001770There are several important syntax enhancements, described in more
1771detail below:
1772
1773 - Augmented assignment, e.g. x += 1
1774
1775 - List comprehensions, e.g. [x**2 for x in range(10)]
1776
1777 - Extended import statement, e.g. import Module as Name
1778
1779 - Extended print statement, e.g. print >> file, "Hello"
1780
1781Other important changes:
1782
1783 - Optional collection of cyclical garbage
1784
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001785Python Enhancement Proposal (PEP)
1786---------------------------------
1787
1788PEP stands for Python Enhancement Proposal. A PEP is a design
1789document providing information to the Python community, or describing
1790a new feature for Python. The PEP should provide a concise technical
1791specification of the feature and a rationale for the feature.
1792
1793We intend PEPs to be the primary mechanisms for proposing new
1794features, for collecting community input on an issue, and for
1795documenting the design decisions that have gone into Python. The PEP
1796author is responsible for building consensus within the community and
1797documenting dissenting opinions.
1798
1799The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001800
1801Augmented Assignment
1802--------------------
1803
1804This must have been the most-requested feature of the past years!
1805Eleven new assignment operators were added:
1806
Guido van Rossume905e952000-09-05 12:42:46 +00001807 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001808
1809For example,
1810
1811 A += B
1812
1813is similar to
1814
1815 A = A + B
1816
1817except that A is evaluated only once (relevant when A is something
1818like dict[index].attr).
1819
1820However, if A is a mutable object, A may be modified in place. Thus,
1821if A is a number or a string, A += B has the same effect as A = A+B
1822(except A is only evaluated once); but if a is a list, A += B has the
1823same effect as A.extend(B)!
1824
1825Classes and built-in object types can override the new operators in
1826order to implement the in-place behavior; the not-in-place behavior is
1827used automatically as a fallback when an object doesn't implement the
1828in-place behavior. For classes, the method name is derived from the
1829method name for the corresponding not-in-place operator by inserting
1830an 'i' in front of the name, e.g. __iadd__ implements in-place
1831__add__.
1832
1833Augmented assignment was implemented by Thomas Wouters.
1834
1835
1836List Comprehensions
1837-------------------
1838
1839This is a flexible new notation for lists whose elements are computed
1840from another list (or lists). The simplest form is:
1841
1842 [<expression> for <variable> in <sequence>]
1843
Guido van Rossum56db0952000-09-06 23:34:25 +00001844For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001845This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001846
1847You can also add a condition:
1848
1849 [<expression> for <variable> in <sequence> if <condition>]
1850
1851For example, [w for w in words if w == w.lower()] would yield the list
1852of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001853than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001854
1855You can also have nested for loops and more than one 'if' clause. For
1856example, here's a function that flattens a sequence of sequences::
1857
1858 def flatten(seq):
1859 return [x for subseq in seq for x in subseq]
1860
1861 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1862
1863This prints
1864
1865 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1866
1867List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001868Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001869
1870
1871Extended Import Statement
1872-------------------------
1873
1874Many people have asked for a way to import a module under a different
1875name. This can be accomplished like this:
1876
1877 import foo
1878 bar = foo
1879 del foo
1880
1881but this common idiom gets old quickly. A simple extension of the
1882import statement now allows this to be written as follows:
1883
1884 import foo as bar
1885
1886There's also a variant for 'from ... import':
1887
1888 from foo import bar as spam
1889
1890This also works with packages; e.g. you can write this:
1891
1892 import test.regrtest as regrtest
1893
1894Note that 'as' is not a new keyword -- it is recognized only in this
1895context (this is only possible because the syntax for the import
1896statement doesn't involve expressions).
1897
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001898Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001899
1900
1901Extended Print Statement
1902------------------------
1903
1904Easily the most controversial new feature, this extension to the print
1905statement adds an option to make the output go to a different file
1906than the default sys.stdout.
1907
1908For example, to write an error message to sys.stderr, you can now
1909write:
1910
1911 print >> sys.stderr, "Error: bad dog!"
1912
1913As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001914evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001915
1916 print >> None, "Hello world"
1917
1918is equivalent to
1919
1920 print "Hello world"
1921
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001922Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001923
1924
1925Optional Collection of Cyclical Garbage
1926---------------------------------------
1927
1928Python is now equipped with a garbage collector that can hunt down
1929cyclical references between Python objects. It's no replacement for
1930reference counting; in fact, it depends on the reference counts being
1931correct, and decides that a set of objects belong to a cycle if all
1932their reference counts can be accounted for from their references to
1933each other. This devious scheme was first proposed by Eric Tiedemann,
1934and brought to implementation by Neil Schemenauer.
1935
1936There's a module "gc" that lets you control some parameters of the
1937garbage collection. There's also an option to the configure script
1938that lets you enable or disable the garbage collection. In 2.0b1,
1939it's on by default, so that we (hopefully) can collect decent user
1940experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001941performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001942off by default in the final 2.0 release.
1943
1944
1945Smaller Changes
1946---------------
1947
1948A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1949map(None, seq1, seq2, ...) when the sequences have the same length;
1950i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1951the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001952zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001953
1954sys.version_info is a tuple (major, minor, micro, level, serial).
1955
1956Dictionaries have an odd new method, setdefault(key, default).
1957dict.setdefault(key, default) returns dict[key] if it exists; if not,
1958it sets dict[key] to default and returns that value. Thus:
1959
1960 dict.setdefault(key, []).append(item)
1961
1962does the same work as this common idiom:
1963
1964 if not dict.has_key(key):
1965 dict[key] = []
1966 dict[key].append(item)
1967
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001968There are two new variants of SyntaxError that are raised for
1969indentation-related errors: IndentationError and TabError.
1970
1971Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1972escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001973
1974The limits on the size of expressions and file in Python source code
1975have been raised from 2**16 to 2**32. Previous versions of Python
1976were limited because the maximum argument size the Python VM accepted
1977was 2**16. This limited the size of object constructor expressions,
1978e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1979limit was raised thanks to a patch by Charles Waldman that effectively
1980fixes the problem. It is now much more likely that you will be
1981limited by available memory than by an arbitrary limit in Python.
1982
1983The interpreter's maximum recursion depth can be modified by Python
1984programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1985limit is the maximum number of recursive calls that can be made by
1986Python code. The limit exists to prevent infinite recursion from
1987overflowing the C stack and causing a core dump. The default value is
19881000. The maximum safe value for a particular platform can be found
1989by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001990
1991New Modules and Packages
1992------------------------
1993
1994atexit - for registering functions to be called when Python exits.
1995
1996imputil - Greg Stein's alternative API for writing custom import
1997hooks.
1998
1999pyexpat - an interface to the Expat XML parser, contributed by Paul
2000Prescod.
2001
2002xml - a new package with XML support code organized (so far) in three
2003subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
2004would fill a volume. There's a special feature whereby a
2005user-installed package named _xmlplus overrides the standard
2006xmlpackage; this is intended to give the XML SIG a hook to distribute
2007backwards-compatible updates to the standard xml package.
2008
2009webbrowser - a platform-independent API to launch a web browser.
2010
2011
Guido van Rossume905e952000-09-05 12:42:46 +00002012Changed Modules
2013---------------
2014
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002015array -- new methods for array objects: count, extend, index, pop, and
2016remove
2017
2018binascii -- new functions b2a_hex and a2b_hex that convert between
2019binary data and its hex representation
2020
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002021calendar -- Many new functions that support features including control
2022over which day of the week is the first day, returning strings instead
2023of printing them. Also new symbolic constants for days of week,
2024e.g. MONDAY, ..., SUNDAY.
2025
2026cgi -- FieldStorage objects have a getvalue method that works like a
2027dictionary's get method and returns the value attribute of the object.
2028
2029ConfigParser -- The parser object has new methods has_option,
2030remove_section, remove_option, set, and write. They allow the module
2031to be used for writing config files as well as reading them.
2032
2033ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002034optionally support the RFC 959 REST command.
2035
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002036gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002037
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002038httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2039the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002040
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002041locale -- implement getdefaultlocale for Win32 and Macintosh
2042
2043marshal -- no longer dumps core when marshaling deeply nested or
2044recursive data structures
2045
2046os -- new functions isatty, seteuid, setegid, setreuid, setregid
2047
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002048os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2049support under Unix.
2050
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002051os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002052
2053os.path -- fix semantics of os.path.commonprefix
2054
2055smtplib -- support for sending very long messages
2056
2057socket -- new function getfqdn()
2058
2059readline -- new functions to read, write and truncate history files.
2060The readline section of the library reference manual contains an
2061example.
2062
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002063select -- add interface to poll system call
2064
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002065shutil -- new copyfileobj function
2066
2067SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2068HTTP server.
2069
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002070Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002071
2072urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002073e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002074
2075whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002076
2077
2078Obsolete Modules
2079----------------
2080
2081None. However note that 1.6 made a whole slew of modules obsolete:
2082stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2083poly, zmod, strop, util, whatsound.
2084
2085
2086Changed, New, Obsolete Tools
2087----------------------------
2088
Tim Peters8b092332000-09-05 20:15:25 +00002089None.
Guido van Rossume905e952000-09-05 12:42:46 +00002090
2091
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002092C-level Changes
2093---------------
2094
2095Several cleanup jobs were carried out throughout the source code.
2096
2097All C code was converted to ANSI C; we got rid of all uses of the
2098Py_PROTO() macro, which makes the header files a lot more readable.
2099
2100Most of the portability hacks were moved to a new header file,
2101pyport.h; several other new header files were added and some old
2102header files were removed, in an attempt to create a more rational set
2103of header files. (Few of these ever need to be included explicitly;
2104they are all included by Python.h.)
2105
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002106Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002107and Win64, especially for the new Intel Itanium processor. Mick also
2108added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002109
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002110The C APIs to return an object's size have been update to consistently
2111use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2112previous versions, the abstract interfaces used PyXXX_Length and the
2113concrete interfaces used PyXXX_Size. The old names,
2114e.g. PyObject_Length, are still available for backwards compatibility
2115at the API level, but are deprecated.
2116
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002117The PyOS_CheckStack function has been implemented on Windows by
2118Fredrik Lundh. It prevents Python from failing with a stack overflow
2119on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002120
2121The GC changes resulted in creation of two new slots on object,
2122tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002123the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002124
2125The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002126C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002127
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002128PyErr_Format has been updated to automatically calculate the size of
2129the buffer needed to hold the formatted result string. This change
2130prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002131
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002132New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002133
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002134PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2135that are the same as their non-Ex counterparts except they take an
2136extra flag argument that tells them to close the file when done.
2137
2138XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002139
Tim Peters8b092332000-09-05 20:15:25 +00002140
2141Windows Changes
2142---------------
2143
2144New popen2/popen3/peopen4 in os module (see Changed Modules above).
2145
2146os.popen is much more usable on Windows 95 and 98. See Microsoft
2147Knowledge Base article Q150956. The Win9x workaround described there
2148is implemented by the new w9xpopen.exe helper in the root of your
2149Python installation. Note that Python uses this internally; it is not
2150a standalone program.
2151
2152Administrator privileges are no longer required to install Python
2153on Windows NT or Windows 2000. If you have administrator privileges,
2154Python's registry info will be written under HKEY_LOCAL_MACHINE.
2155Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002156under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002157uses of Python, but will prevent some advanced uses from working
2158(for example, running a Python script as an NT service, or possibly
2159from CGI).
2160
2161[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2162installer; instead, it installs the needed Tcl/Tk files directly in the
2163Python directory. If you already have a Tcl/Tk installation, this
2164wastes some disk space (about 4 Megs) but avoids problems with
2165conflicting Tcl/Tk installations, and makes it much easier for Python
2166to ensure that Tcl/Tk can find all its files.
2167
2168[This was new in 1.6] The Windows installer now installs by default in
2169\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2170
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002171
2172Updates to the changes between 1.5.2 and 1.6
2173--------------------------------------------
2174
2175The 1.6 NEWS file can't be changed after the release is done, so here
2176is some late-breaking news:
2177
2178New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2179and changes to getlocale() and setlocale().
2180
2181The new module is now enabled per default.
2182
2183It is not true that the encodings codecs cannot be used for normal
2184strings: the string.encode() (which is also present on 8-bit strings
2185!) allows using them for 8-bit strings too, e.g. to convert files from
2186cp1252 (Windows) to latin-1 or vice-versa.
2187
2188Japanese codecs are available from Tamito KAJIYAMA:
2189http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2190
2191
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002192======================================================================