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Tim Petersb07352e2001-09-08 01:25:47 +00001What's New in Python 2.2a4?
2===========================
3
Guido van Rossum808eea72001-09-25 04:15:41 +00004Type/class unification and new-style classes
5
6- pydoc and inspect are now aware of new-style classes;
7 e.g. help(list) at the interactive prompt now shows proper
8 documentation for all operations on list objects.
9
10- Applications using Jim Fulton's ExtensionClass module can now safely
11 be used with Python 2.2. In particular, Zope 2.4.1 now works with
12 Python 2.2 (as well as with Python 2.1.1). The Demo/metaclass
13 examples also work again. It is hoped that Gtk and Boost also work
14 with 2.2a4 and beyond. (If you can confirm this, please write
15 webmaster@python.org; if there are still problems, please open a bug
16 report on SourceForge.)
Tim Petersb07352e2001-09-08 01:25:47 +000017
Tim Peters66c1a522001-09-24 21:17:50 +000018- property() now takes 4 keyword arguments: fget, fset, fdel and doc.
19 These map to readonly attributes 'fget', 'fset', 'fdel', and '__doc__'
20 in the constructed property object. fget, fset and fdel weren't
21 discoverable from Python in 2.2a3. __doc__ is new, and allows to
22 associate a docstring with a property.
23
Guido van Rossum808eea72001-09-25 04:15:41 +000024- Comparison overloading is now more completely implemented. For
25 example, a str subclass instance can properly be compared to a str
26 instance, and it can properly overload comparison. Ditto for most
27 other built-in object types.
28
29- The repr() of new-style classes has changed; instead of <type
30 'M.Foo'> a new-style class is now rendered as <class 'M.Foo'>,
31 *except* for built-in types, which are still rendered as <type
32 'Foo'> (to avoid upsetting existing code that might parse or
33 otherwise rely on repr() of certain type objects).
34
35- The repr() of new-style objects is now always <Foo object at XXX>;
36 previously, it was sometimes <Foo instance at XXX>.
37
38- For new-style classes, what was previously called __getattr__ is now
39 called __getattribute__. This method, if defined, is called for
40 *every* attribute access. A new __getattr__ hook mor similar to the
41 one in classic classes is defined which is called only if regular
42 attribute access raises AttributeError; to catch *all* attribute
43 access, you can use __getattribute__ (for new-style classes). If
44 both are defined, __getattribute__ is called first, and if it raises
45 AttributeError, __getattr__ is called.
46
47- The __class__ attribute of new-style objects can be assigned to.
48 The new class must have the same C-level object layout as the old
49 class.
50
51- The builtin file type can be subclassed now. In the usual pattern,
52 "file" is the name of the builtin type, and file() is a new builtin
53 constructor, with the same signature as the builtin open() function.
54 file() is now the preferred way to open a file.
55
56- Previously, __new__ would only see sequential arguments passed to
57 the type in a constructor call; __init__ would see both sequential
58 and keyword arguments. This made no sense whatsoever any more, so
59 now both __new__ and __init__ see all arguments.
60
61- Previously, hash() applied to an instance of a subclass of str or
62 unicode always returned 0. This has been repaired.
63
64- Previously, an operation on an instance of a subclass of an
65 immutable type (int, long, float, complex, tuple, str, unicode),
66 where the subtype didn't override the operation (and so the
67 operation was handled by the builtin type), could return that
68 instance instead a value of the base type. For example, if s was of
69 a str sublass type, s[:] returned s as-is. Now it returns a str
70 with the same value as s.
71
72Core
73
Tim Peters2c9aa5e2001-09-23 04:06:05 +000074- file.writelines() now accepts any iterable object producing strings.
75
Marc-André Lemburgaefd7662001-09-20 12:59:37 +000076- PyUnicode_FromEncodedObject() now works very much like
77 PyObject_Str(obj) in that it tries to use __str__/tp_str
78 on the object if the object is not a string or buffer. This
79 makes unicode() behave like str() when applied to non-string/buffer
80 objects.
81
Martin v. Löwis2777c022001-09-19 13:47:32 +000082- PyFile_WriteObject now passes Unicode object to the file's write
83 method. As a result, all file-like object which may be the target
84 of a print statement must support Unicode objects, i.e. they must
85 at least convert them into ASCII strings.
86
Guido van Rossum624c8af2001-09-18 15:21:04 +000087- Thread scheduling on Solaris should be improved; it is no longer
88 necessary to insert a small sleep at the start of a thread in order
89 to let other runnable threads be scheduled.
90
Tim Petersb07352e2001-09-08 01:25:47 +000091Library
92
Marc-André Lemburgbf990172001-09-27 14:17:33 +000093- StringIO.StringIO instances and cStringIO.StringIO instances support
94 read character buffer compatible objects for their .write() methods.
95 These objects are converted to strings and then handled as such
96 by the instances.
97
Barry Warsaw2f600732001-09-24 04:28:10 +000098- The "email" package has been added. This is basically a port of the
99 mimelib package <http://sf.net/projects/mimelib> with API changes
100 and some implementations updated to use iterators and generators.
101
Tim Peters8a9c2842001-09-22 21:30:22 +0000102- difflib.ndiff() and difflib.Differ.compare() are generators now. This
103 restores the ability of Tools/scripts/ndiff.py to start producing output
104 before the entire comparison is complete.
105
Barry Warsaw58b072d2001-09-22 04:44:21 +0000106- StringIO.StringIO instances and cStringIO.StringIO instances support
107 iteration just like file objects (i.e. their .readline() method is
108 called for each iteration until it returns an empty string).
109
Marc-André Lemburg494f2ae2001-09-19 11:33:31 +0000110- The codecs module has grown four new helper APIs to access
111 builtin codecs: getencoder(), getdecoder(), getreader(),
112 getwriter().
113
Guido van Rossum624c8af2001-09-18 15:21:04 +0000114- SimpleXMLRPCServer: a new module (based upon SimpleHTMLServer)
115 simplifies writing XML RPC servers.
116
117- os.path.realpath(): a new function that returns the absoute pathname
118 after interpretation of symbolic links. On non-Unix systems, this
119 is an alias for os.path.abspath().
120
Tim Peters16a77ad2001-09-08 04:00:12 +0000121- operator.indexOf() (PySequence_Index() in the C API) now works with any
122 iterable object.
123
Guido van Rossum624c8af2001-09-18 15:21:04 +0000124- smtplib now supports various authentication and security features of
125 the SMTP protocol through the new login() and starttls() methods.
Guido van Rossumd8185ca2001-09-14 16:35:16 +0000126
Guido van Rossum624c8af2001-09-18 15:21:04 +0000127- hmac: a new module implementing keyed hashing for message
128 authentication.
129
130- mimetypes now recognizes more extensions and file types. At the
131 same time, some mappings not sanctioned by IANA were removed.
Guido van Rossumd8185ca2001-09-14 16:35:16 +0000132
Guido van Rossum624c8af2001-09-18 15:21:04 +0000133- The "compiler" package has been brought up to date to the state of
Guido van Rossumc9ed5dc2001-09-20 05:30:24 +0000134 Python 2.2 bytecode generation. It has also been promoted from a
135 Tool to a standard library package. (Tools/compiler still exists as
136 a sample driver.)
137
Guido van Rossumc9ed5dc2001-09-20 05:30:24 +0000138Tools
Guido van Rossum624c8af2001-09-18 15:21:04 +0000139
Tim Petersb07352e2001-09-08 01:25:47 +0000140Build
141
Guido van Rossum624c8af2001-09-18 15:21:04 +0000142- Large file support (LFS) is now automatic when the platform supports
143 it; no more manual configuration tweaks are needed. On Linux, at
144 least, it's possible to have a system whose C library supports large
145 files but whose kernel doesn't; in this case, large file support is
146 still enabled but doesn't do you any good unless you upgrade your
147 kernel or share your Python executable with another system whose
148 kernel has large file support.
149
150- The configure script now supplies plausible defaults in a
151 cross-compilation environment. This doesn't mean that the supplied
152 values are always correct, or that cross-compilation now works
153 flawlessly -- but it's a first step (and it shuts up most of
154 autoconf's warnings about AC_TRY_RUN).
155
156- The Unix build is now a bit less chatty, courtesy of the parser
157 generator. The build is completely silent (except for errors) when
158 using "make -s", thanks to a -q option to setup.py.
159
Tim Petersb07352e2001-09-08 01:25:47 +0000160C API
161
Guido van Rossum624c8af2001-09-18 15:21:04 +0000162- The "structmember" API now supports some new flag bits to deny read
163 and/or write access to attributes in restricted execution mode.
164
Tim Petersb07352e2001-09-08 01:25:47 +0000165New platforms
166
Guido van Rossum624c8af2001-09-18 15:21:04 +0000167- Compaq's iPAQ handheld, running the "familiar" Linux distribution
168 (http://familiar.handhelds.org).
169
Tim Petersb07352e2001-09-08 01:25:47 +0000170Tests
171
Tim Peters8a9c2842001-09-22 21:30:22 +0000172- The "classic" standard tests, which work by comparing stdout to
173 an expected-output file under Lib/test/output/, no longer stop at
174 the first mismatch. Instead the test is run to completion, and a
175 variant of ndiff-style comparison is used to report all differences.
176 This is much easier to understand than the previous style of reporting.
177
178- The unittest-based standard tests now use regrtest's test_main()
179 convention, instead of running as a side-effect of merely being
180 imported. This allows these tests to be run in more natural and
181 flexible ways as unittests, outside the regrtest framework.
182
183- regrtest.py is much better integrated with unittest and doctest now,
184 especially in regard to reporting errors.
185
Tim Petersb07352e2001-09-08 01:25:47 +0000186Windows
187
Guido van Rossum624c8af2001-09-18 15:21:04 +0000188- Large file support now also works for files > 4GB, on filesystems
Tim Peters8a9c2842001-09-22 21:30:22 +0000189 that support it (NTFS under Windows 2000). See "What's New in
190 Python 2.2a3" for more detail.
Guido van Rossum624c8af2001-09-18 15:21:04 +0000191
Tim Petersb07352e2001-09-08 01:25:47 +0000192
Tim Petersedc99312001-08-22 21:36:50 +0000193What's New in Python 2.2a3?
194===========================
195
196Core
197
Tim Peters9fffa3e2001-09-04 05:14:19 +0000198- Conversion of long to float now raises OverflowError if the long is too
199 big to represent as a C double.
200
Tim Peters32f453e2001-09-03 08:35:41 +0000201- The 3-argument builtin pow() no longer allows a third non-None argument
202 if either of the first two arguments is a float, or if both are of
203 integer types and the second argument is negative (in which latter case
204 the arguments are converted to float, so this is really the same
205 restriction).
206
Tim Peters5d2b77c2001-09-03 05:47:38 +0000207- The builtin dir() now returns more information, and sometimes much
208 more, generally naming all attributes of an object, and all attributes
209 reachable from the object via its class, and from its class's base
210 classes, and so on from them too. Example: in 2.2a2, dir([]) returned
211 an empty list. In 2.2a3,
212
213 >>> dir([])
214 ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__',
215 '__eq__', '__ge__', '__getattr__', '__getitem__', '__getslice__',
216 '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__le__',
217 '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__repr__',
218 '__rmul__', '__setattr__', '__setitem__', '__setslice__', '__str__',
219 'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove',
220 'reverse', 'sort']
221
222 dir(module) continues to return only the module's attributes, though.
223
Tim Petersbdee63f2001-09-02 03:40:59 +0000224- Overflowing operations on plain ints now return a long int rather
Guido van Rossumae457142001-08-31 18:31:35 +0000225 than raising OverflowError. This is a partial implementation of PEP
226 237. You can use -Wdefault::OverflowWarning to enable a warning for
227 this situation, and -Werror::OverflowWarning to revert to the old
228 OverflowError exception.
229
Guido van Rossum61c345f2001-09-04 03:26:15 +0000230- A new command line option, -Q<arg>, is added to control run-time
Guido van Rossumae457142001-08-31 18:31:35 +0000231 warnings for the use of classic division. (See PEP 238.) Possible
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000232 values are -Qold, -Qwarn, -Qwarnall, and -Qnew. The default is
233 -Qold, meaning the / operator has its classic meaning and no
234 warnings are issued. Using -Qwarn issues a run-time warning about
235 all uses of classic division for int and long arguments; -Qwarnall
236 also warns about classic division for float and complex arguments
237 (for use with fixdiv.py). Using -Qnew is questionable; it turns on
238 new division by default, but only in the __main__ module. You can
239 usefully combine -Qwarn or -Qwarnall and -Qnew: this gives the
240 __main__ module new division, and warns about classic division
241 everywhere else.
Guido van Rossumae457142001-08-31 18:31:35 +0000242
Tim Petersbdee63f2001-09-02 03:40:59 +0000243- Many built-in types can now be subclassed. This applies to int,
Guido van Rossumae457142001-08-31 18:31:35 +0000244 long, float, str, unicode, and tuple. (The types complex, list and
245 dictionary can also be subclassed; this was introduced earlier.)
246 Note that restrictions apply when subclassing immutable built-in
247 types: you can only affect the value of the instance by overloading
248 __new__. You can add mutable attributes, and the subclass instances
249 will have a __dict__ attribute, but you cannot change the "value"
250 (as implemented by the base class) of an immutable subclass instance
251 once it is created.
252
Guido van Rossumaaf80c82001-09-02 13:44:35 +0000253- The dictionary constructor now takes an optional argument, a
254 mapping-like object, and initializes the dictionary from its
255 (key, value) pairs.
256
Tim Petersbdee63f2001-09-02 03:40:59 +0000257- A new built-in type, super, has been added. This facilitates making
Guido van Rossumae457142001-08-31 18:31:35 +0000258 "cooperative super calls" in a multiple inheritance setting. For an
259 explanation, see http://www.python.org/2.2/descrintro.html#cooperation
260
Guido van Rossum8d7234d2001-09-06 22:02:58 +0000261- A new built-in type, property, has been added. This enables the
262 creation of "properties". These are attributes implemented by
263 getter and setter functions (or only one of these for read-only or
264 write-only attributes), without the need to override __getattr__.
265 See http://www.python.org/2.2/descrintro.html#property
Guido van Rossumae457142001-08-31 18:31:35 +0000266
Tim Petersbdee63f2001-09-02 03:40:59 +0000267- The syntax of floating-point and imaginary literals has been
Tim Petersd507dab2001-08-30 20:51:59 +0000268 liberalized, to allow leading zeroes. Examples of literals now
269 legal that were SyntaxErrors before:
270
271 00.0 0e3 0100j 07.5 00000000000000000008.
272
Tim Petersbdee63f2001-09-02 03:40:59 +0000273- An old tokenizer bug allowed floating point literals with an incomplete
Tim Petersc6d95812001-08-28 20:56:27 +0000274 exponent, such as 1e and 3.1e-. Such literals now raise SyntaxError.
275
Tim Petersedc99312001-08-22 21:36:50 +0000276Library
277
Martin v. Löwiscb227c92001-09-06 08:54:16 +0000278- telnetlib includes symbolic names for the options, and support for
279 setting an option negotiation callback.
280
Tim Petersa40c7932001-09-05 22:36:56 +0000281- The new C standard no longer requires that math libraries set errno to
282 ERANGE on overflow. For platform libraries that exploit this new
283 freedom, Python's overflow-checking was wholly broken. A new overflow-
284 checking scheme attempts to repair that, but may not be reliable on all
285 platforms (C doesn't seem to provide anything both useful and portable
286 in this area anymore).
287
Martin v. Löwis44f86962001-09-05 13:44:54 +0000288- Asynchronous timeout actions are available through the new class
289 threading.Timer.
290
Tim Peters78526162001-09-05 00:53:45 +0000291- math.log and math.log10 now return sensible results for even huge
292 long arguments. For example, math.log10(10 ** 10000) ~= 10000.0.
293
Tim Petersbdee63f2001-09-02 03:40:59 +0000294- A new function, imp.lock_held(), returns 1 when the import lock is
Tim Peters69232342001-08-30 05:16:13 +0000295 currently held. See the docs for the imp module.
296
Tim Petersbdee63f2001-09-02 03:40:59 +0000297- pickle, cPickle and marshal on 32-bit platforms can now correctly read
Tim Peters82112372001-08-29 02:28:42 +0000298 dumps containing ints written on platforms where Python ints are 8 bytes.
299 When read on a box where Python ints are 4 bytes, such values are
300 converted to Python longs.
301
Tim Petersbdee63f2001-09-02 03:40:59 +0000302- In restricted execution mode (using the rexec module), unmarshalling
Guido van Rossumae457142001-08-31 18:31:35 +0000303 code objects is no longer allowed. This plugs a security hole.
304
Steve Purcell6091cd62001-09-06 16:05:17 +0000305- unittest.TestResult instances no longer store references to tracebacks
306 generated by test failures. This prevents unexpected dangling references
307 to objects that should be garbage collected between tests.
308
Tim Petersedc99312001-08-22 21:36:50 +0000309Tools
310
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000311- Tools/scripts/fixdiv.py has been added which can be used to fix
312 division operators as per PEP 238.
313
Tim Petersedc99312001-08-22 21:36:50 +0000314Build
315
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000316- If you are an adventurous person using Mac OS X you may want to look at
317 Mac/OSX. There is a Makefile there that will build Python as a real Mac
318 application, which can be used for experimenting with Carbon or Cocoa.
319 Discussion of this on pythonmac-sig, please.
320
Tim Peters7eea37e2001-09-04 22:08:56 +0000321C API
322
323- New function PyObject_Dir(obj), like Python __builtin__.dir(obj).
Tim Peters69232342001-08-30 05:16:13 +0000324
Tim Peters9fffa3e2001-09-04 05:14:19 +0000325- Note that PyLong_AsDouble can fail! This has always been true, but no
326 callers checked for it. It's more likely to fail now, because overflow
327 errors are properly detected now. The proper way to check:
328
329 double x = PyLong_AsDouble(some_long_object);
330 if (x == -1.0 && PyErr_Occurred()) {
331 /* The conversion failed. */
332 }
333
Tim Petersbdee63f2001-09-02 03:40:59 +0000334- The GC API has been changed. Extensions that use the old API will still
Neil Schemenauer4042c692001-08-30 15:38:01 +0000335 compile but will not participate in GC. To upgrade an extension
336 module:
337
338 - rename Py_TPFLAGS_GC to PyTPFLAGS_HAVE_GC
Tim Petersd507dab2001-08-30 20:51:59 +0000339
Neil Schemenauer4042c692001-08-30 15:38:01 +0000340 - use PyObject_GC_New or PyObject_GC_NewVar to allocate objects and
341 PyObject_GC_Del to deallocate them
Tim Petersd507dab2001-08-30 20:51:59 +0000342
Neil Schemenauer4042c692001-08-30 15:38:01 +0000343 - rename PyObject_GC_Init to PyObject_GC_Track and PyObject_GC_Fini
344 to PyObject_GC_UnTrack
Tim Petersd507dab2001-08-30 20:51:59 +0000345
Neil Schemenauer4042c692001-08-30 15:38:01 +0000346 - remove PyGC_HEAD_SIZE from object size calculations
347
348 - remove calls to PyObject_AS_GC and PyObject_FROM_GC
349
Tim Petersbdee63f2001-09-02 03:40:59 +0000350- Two new functions: PyString_FromFormat() and PyString_FromFormatV().
Guido van Rossumae457142001-08-31 18:31:35 +0000351 These can be used safely to construct string objects from a
352 sprintf-style format string (similar to the format string supported
353 by PyErr_Format()).
Tim Peters69232342001-08-30 05:16:13 +0000354
Tim Petersedc99312001-08-22 21:36:50 +0000355New platforms
356
Tim Petersb7da0902001-09-02 23:01:43 +0000357- Stephen Hansen contributed patches sufficient to get a clean compile
358 under Borland C (Windows), but he reports problems running it and ran
359 out of time to complete the port. Volunteers? Expect a MemoryError
360 when importing the types module; this is probably shallow, and
361 causing later failures too.
Tim Petersbdee63f2001-09-02 03:40:59 +0000362
Tim Petersedc99312001-08-22 21:36:50 +0000363Tests
364
365Windows
366
Tim Peters6e13a562001-09-06 00:32:15 +0000367- Large file support is now enabled on Win32 platforms as well as on
368 Win64. This means that, for example, you can use f.tell() and f.seek()
369 to manipulate files larger than 2 gigabytes (provided you have enough
370 disk space, and are using a Windows filesystem that supports large
Tim Peters9a9471c2001-09-11 23:18:51 +0000371 partitions). Windows filesystem limits: FAT has a 2GB (gigabyte)
372 filesize limit, and large file support makes no difference there.
373 FAT32's limit is 4GB, and files >= 2GB are easier to use from Python now.
374 NTFS has no practical limit on file size, and files of any size can be
375 used from Python now.
Tim Peters6e13a562001-09-06 00:32:15 +0000376
Tim Petersbdee63f2001-09-02 03:40:59 +0000377- The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
Tim Peters402d5982001-08-27 06:37:48 +0000378 points to command.com (patch from Brian Quinlan).
379
Tim Petersedc99312001-08-22 21:36:50 +0000380
Tim Peters20f51a72001-07-21 02:31:40 +0000381What's New in Python 2.2a2?
382===========================
383
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000384Build
385
Barry Warsaw18b2ecf2001-08-22 20:26:56 +0000386- Tim Peters developed a brand new Windows installer using Wise 8.1,
387 generously donated to us by Wise Solutions.
388
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000389- configure supports a new option --enable-unicode, with the values
390 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
391 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000392
Jack Jansen32ce0cd2001-08-21 19:28:20 +0000393- A new configure option --enable-framework builds a Mac OS X framework,
394 which "make frameworkinstall" will install. This provides a starting
395 point for more mac-like functionality, join pythonmac-sig@python.org
396 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000397
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000398- The NeXT platform is no longer supported.
399
400- The `new' module is now statically linked.
401
Tim Peters0afb6092001-08-15 06:06:44 +0000402Tools
403
404- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +0000405 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +0000406 the module docstring for details.
407
Tim Peters20f51a72001-07-21 02:31:40 +0000408Tests
409
Tim Peters5e824c32001-08-12 22:25:01 +0000410- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000411 platforms, allowing to give clearer test result output. regrtest
412 also has optional --use/-u switch to run normally disabled tests
413 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +0000414
Tim Peters20f51a72001-07-21 02:31:40 +0000415- Several new tests in the standard test suite, with special thanks to
416 Nick Mathewson.
417
418Core
419
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000420- The floor division operator // has been added as outlined in PEP
421 238. The / operator still provides classic division (and will until
422 Python 3.0) unless "from __future__ import division" is included, in
423 which case the / operator will provide true division. The operator
424 module provides truediv() and floordiv() functions. Augmented
425 assignment variants are included, as are the equivalent overloadable
426 methods and C API methods. See the PEP for a full discussion:
427 <http://python.sf.net/peps/pep-0238.html>
428
Tim Peters6cd6a822001-08-17 22:11:27 +0000429- Future statements are now effective in simulated interactive shells
430 (like IDLE). This should "just work" by magic, but read Michael
431 Hudson's "Future statements in simulated shells" PEP 264 for full
432 details: <http://python.sf.net/peps/pep-0264.html>.
433
Guido van Rossumf86ddd22001-08-17 21:21:04 +0000434- The type/class unification (PEP 252-253) was integrated into the
435 trunk and is not so tentative any more (the exact specification of
436 some features is still tentative). A lot of work has done on fixing
437 bugs and adding robustness and features (performance still has to
438 come a long way).
439
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000440- Warnings about a mismatch in the Python API during extension import
441 now use the Python warning framework (which makes it possible to
442 write filters for these warnings).
443
Barry Warsaw9b3be7f2001-08-14 18:35:02 +0000444- A function's __dict__ (aka func_dict) will now always be a
445 dictionary. It used to be possible to delete it or set it to None,
446 but now both actions raise TypeErrors. It is still legal to set it
447 to a dictionary object. Getting func.__dict__ before any attributes
448 have been assigned now returns an empty dictionary instead of None.
449
Guido van Rossum32aa5d22001-09-05 18:43:35 +0000450- A new command line option, -E, was added which disables the use of
451 all environment variables, or at least those that are specifically
452 significant to Python. Usually those have a name starting with
453 "PYTHON". This was used to fix a problem where the tests fail if
454 the user happens to have PYTHONHOME or PYTHONPATH pointing to an
455 older distribution.
456
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000457Library
458
Tim Peters5e824c32001-08-12 22:25:01 +0000459- New class Differ and new functions ndiff() and restore() in difflib.py.
460 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +0000461 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +0000462
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000463- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
464 value using the minimal quoting required for the value; more
465 reliable than using xml.sax.saxutils.escape() for attribute values.
466
467- Readline completion support for cmd.Cmd was added.
468
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000469- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
470
471- Added function threading.BoundedSemaphore()
472
473- Added Ka-Ping Yee's cgitb.py module.
474
475- The `new' module now exposes the CO_xxx flags.
476
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000477New platforms
478
479C API
480
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000481- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
482 which provide a cross-platform implementations for the
483 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
484 the standard sprintf() and vsprintf() C lib APIs, these versions
485 apply bounds checking on the used buffer which enhances protection
486 against buffer overruns.
487
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000488- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000489 and extensions using different Unicode widths is rendered next to
490 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000491 will result in an ImportError. Unicode extensions writers must make
492 sure to check the Unicode width compatibility in their extensions by
493 using at least one of the mangled Unicode APIs in the extension.
494
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000495- Two new flags METH_NOARGS and METH_O are available in method definition
496 tables to simplify implementation of methods with no arguments and a
497 single untyped argument. Calling such methods is more efficient than
498 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
499 deprecated.
500
Tim Petersc1731372001-08-04 08:12:36 +0000501Windows
502
503- "import module" now compiles module.pyw if it exists and nothing else
504 relevant is found.
505
Tim Peters20f51a72001-07-21 02:31:40 +0000506
Guido van Rossum55a78992001-07-17 17:22:32 +0000507What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000508===========================
509
510Core
Tim Petersa814db52001-05-14 07:05:58 +0000511
Tim Peters6d6c1a32001-08-02 04:15:00 +0000512- TENTATIVELY, a large amount of code implementing much of what's
513 described in PEP 252 (Making Types Look More Like Classes) and PEP
514 253 (Subtyping Built-in Types) was added. This will be released
515 with Python 2.2a1. Documentation will be provided separately
516 through http://www.python.org/2.2/. The purpose of releasing this
517 with Python 2.2a1 is to test backwards compatibility. It is
518 possible, though not likely, that a decision is made not to release
519 this code as part of 2.2 final, if any serious backwards
520 incompapatibilities are found during alpha testing that cannot be
521 repaired.
522
Guido van Rossum55a78992001-07-17 17:22:32 +0000523- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000524 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000525 more 'yield' statements. See PEP 255. Since this adds a new
526 keyword to the language, this feature must be enabled by including a
527 future statement: "from __future__ import generators" (see PEP 236).
528 Generators will become a standard feature in a future release
529 (probably 2.3). Without this future statement, 'yield' remains an
530 ordinary identifier, but a warning is issued each time it is used.
531 (These warnings currently don't conform to the warnings framework of
532 PEP 230; we intend to fix this in 2.2a2.)
533
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000534- The UTF-16 codec was modified to be more RFC compliant. It will now
535 only remove BOM characters at the start of the string and then
536 only if running in native mode (UTF-16-LE and -BE won't remove a
537 leading BMO character).
538
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000539- Strings now have a new method .decode() to complement the already
540 existing .encode() method. These two methods provide direct access
541 to the corresponding decoders and encoders of the registered codecs.
542
543 To enhance the usability of the .encode() method, the special
544 casing of Unicode object return values was dropped (Unicode objects
545 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000546
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000547 Both methods will now return whatever the codec in charge of the
548 requested encoding returns as object, e.g. Unicode codecs will
549 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
550 will return u"äöü"). This enables codec writer to create codecs
551 for various simple to use conversions.
552
553 New codecs were added to demonstrate these new features (the .encode()
554 and .decode() columns indicate the type of the returned objects):
555
556 Name | .encode() | .decode() | Description
557 ----------------------------------------------------------------------
558 uu | string | string | UU codec (e.g. for email)
559 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000560 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000561 zlib | string | string | zlib compression
562 hex | string | string | 2-byte hex codec
563 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
564
Mark Hammond2a0af792001-05-14 03:09:36 +0000565- Some operating systems now support the concept of a default Unicode
566 encoding for file system operations. Notably, Windows supports 'mbcs'
567 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000568 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000569 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000570
571 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000572 functions that return filenames (such as os.listdir()) to return Python
573 string objects pre-encoded using the default file system encoding for
574 the platform. As this encoding is likely to be different from Python's
575 default encoding, converting this name to a Unicode object before passing
576 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000577 would attempt to use its default encoding (generally ASCII) rather than
578 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000579
Tim Petersa814db52001-05-14 07:05:58 +0000580 In general, this change simply removes surprises when working with
581 Unicode and the file system, making these operations work as you expect,
582 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000583 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000584
Tim Peters61dff2b2001-05-08 15:43:37 +0000585- Float (and complex) literals in source code were evaluated to full
586 precision only when running from a .py file; the same code loaded from a
587 .pyc (or .pyo) file could suffer numeric differences starting at about the
588 12th significant decimal digit. For example, on a machine with IEEE-754
589 floating arithmetic,
590
591 x = 9007199254740992.0
592 print long(x)
593
594 printed 9007199254740992 if run directly from .py, but 9007199254740000
595 if from a compiled (.pyc or .pyo) file. This was due to marshal using
596 str(float) instead of repr(float) when building code objects. marshal
597 now uses repr(float) instead, which should reproduce floats to full
598 machine precision (assuming the platform C float<->string I/O conversion
599 functions are of good quality).
600
601 This may cause floating-point results to change in some cases, and
602 usually for the better, but may also cause numerically unstable
603 algorithms to break.
604
Tim Peters2f228e72001-05-13 00:19:31 +0000605- The implementation of dicts suffers fewer collisions, which has speed
606 benefits. However, the order in which dict entries appear in dict.keys(),
607 dict.values() and dict.items() may differ from previous releases for a
608 given dict. Nothing is defined about this order, so no program should
609 rely on it. Nevertheless, it's easy to write test cases that rely on the
610 order by accident, typically because of printing the str() or repr() of a
611 dict to an "expected results" file. See Lib/test/test_support.py's new
612 sortdict(dict) function for a simple way to display a dict in sorted
613 order.
614
Tim Peters7a3bfc32001-06-12 01:22:22 +0000615- Many other small changes to dicts were made, resulting in faster
616 operation along the most common code paths.
617
Guido van Rossum10315822001-05-01 20:54:30 +0000618- Dictionary objects now support the "in" operator: "x in dict" means
619 the same as dict.has_key(x).
620
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000621- The update() method of dictionaries now accepts generic mapping
622 objects. Specifically the argument object must support the .keys()
623 and __getitem__() methods. This allows you to say, for example,
624 {}.update(UserDict())
625
Guido van Rossum10315822001-05-01 20:54:30 +0000626- Iterators were added; this is a generalized way of providing values
627 to a for loop. See PEP 234. There's a new built-in function iter()
628 to return an iterator. There's a new protocol to get the next value
629 from an iterator using the next() method (in Python) or the
630 tp_iternext slot (in C). There's a new protocol to get iterators
631 using the __iter__() method (in Python) or the tp_iter slot (in C).
632 Iterating (i.e. a for loop) over a dictionary generates its keys.
633 Iterating over a file generates its lines.
634
Tim Petersf553f892001-05-01 20:45:31 +0000635- The following functions were generalized to work nicely with iterator
636 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000637 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000638 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
639 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000640 join() method of strings
641 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000642 'x in y' and 'x not in y' (PySequence_Contains() in C API)
643 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000644 right-hand side of assignment statements with multiple targets, such as
645 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000646
Tim Petersd85e1022001-05-11 21:51:48 +0000647- Accessing module attributes is significantly faster (for example,
648 random.random or os.path or yourPythonModule.yourAttribute).
649
Tim Peterse63415e2001-05-08 04:38:29 +0000650- Comparing dictionary objects via == and != is faster, and now works even
651 if the keys and values don't support comparisons other than ==.
652
Tim Peters95bf9392001-05-10 08:32:44 +0000653- Comparing dictionaries in ways other than == and != is slower: there were
654 insecurities in the dict comparison implementation that could cause Python
655 to crash if the element comparison routines for the dict keys and/or
656 values mutated the dicts. Making the code bulletproof slowed it down.
657
Tim Peterseb28ef22001-06-02 05:27:19 +0000658- Collisions in dicts are resolved via a new approach, which can help
659 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000660 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000661 faster now. Thanks to Christian Tismer for pointing out the cause and
662 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000663
Tim Peters52e155e2001-06-16 05:42:57 +0000664- repr() is much faster for large containers (dict, list, tuple).
665
666
Tim Petersa814db52001-05-14 07:05:58 +0000667Library
668
Fred Drake960fdf92001-07-20 18:38:26 +0000669- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
670 were added to the string module. These a locale-indenpendent
671 constants, unlike letters, lowercase, and uppercase. These are now
672 use in appropriate locations in the standard library.
673
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000674- The flags used in dlopen calls can now be configured using
675 sys.setdlopenflags and queried using sys.getdlopenflags.
676
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000677- Fredrik Lundh's xmlrpclib is now a standard library module. This
678 provides full client-side XML-RPC support. In addition,
679 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
680 one asyncore-based). Thanks to Eric Raymond for the documentation.
681
Guido van Rossum643d3912001-07-05 14:46:25 +0000682- The xrange() object is simplified: it no longer supports slicing,
683 repetition, comparisons, efficient 'in' checking, the tolist()
684 method, or the start, stop and step attributes. See PEP 260.
685
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000686- A new function fnmatch.filter to filter lists of file names was added.
687
Barry Warsawffd674d2001-05-22 16:00:10 +0000688- calendar.py uses month and day names based on the current locale.
689
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000690- strop is now *really* obsolete (this was announced before with 1.6),
691 and issues DeprecationWarning when used (except for the four items
692 that are still imported into string.py).
693
Tim Petersa814db52001-05-14 07:05:58 +0000694- Cookie.py now sorts key+value pairs by key in output strings.
695
696- pprint.isrecursive(object) didn't correctly identify recursive objects.
697 Now it does.
698
Tim Peters95b3f782001-05-14 18:39:41 +0000699- pprint functions now much faster for large containers (tuple, list, dict).
700
Tim Peters7b9542a2001-06-10 23:40:19 +0000701- New 'q' and 'Q' format codes in the struct module, corresponding to C
702 types "long long" and "unsigned long long" (on Windows, __int64). In
703 native mode, these can be used only when the platform C compiler supports
704 these types (when HAVE_LONG_LONG is #define'd by the Python config
705 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000706 In standard mode, 'q' and 'Q' are supported on all platforms, and are
707 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000708
Guido van Rossum83213cc2001-06-12 16:48:52 +0000709- The site module installs a new built-in function 'help' that invokes
710 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
711 it displays a message reminding the user to use 'help()' or
712 'help(object)'.
713
Tim Petersa814db52001-05-14 07:05:58 +0000714Tests
715
716- New test_mutants.py runs dict comparisons where the key and value
717 comparison operators mutute the dicts randomly during comparison. This
718 rapidly causes Python to crash under earlier releases (not for the faint
719 of heart: it can also cause Win9x to freeze or reboot!).
720
721- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000722 pprint.isreadable() return sensible results. Also verifies that simple
723 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000724
Tim Peters4324aa32001-05-28 22:30:08 +0000725C API
726
727- Removed the unused last_is_sticky argument from the internal
728 _PyTuple_Resize(). If this affects you, you were cheating.
729
730
Guido van Rossum55a78992001-07-17 17:22:32 +0000731======================================================================
732
733
Guido van Rossumffe13be2001-04-16 18:46:45 +0000734What's New in Python 2.1 (final)?
735=================================
736
737We only changed a few things since the last release candidate, all in
738Python library code:
739
740- A bug in the locale module was fixed that affected locales which
741 define no grouping for numeric formatting.
742
743- A few bugs in the weakref module's implementations of weak
744 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
745 and the test suite was updated to check for these bugs.
746
747- An old bug in the os.path.walk() function (introduced in Python
748 2.0!) was fixed: a non-existent file would cause an exception
749 instead of being ignored.
750
751- Fixed a few bugs in the new symtable module found by Neil Norwitz's
752 PyChecker.
753
754
Guido van Rossum5b08f132001-04-16 02:05:23 +0000755What's New in Python 2.1c2?
756===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000757
Guido van Rossum5b08f132001-04-16 02:05:23 +0000758A flurry of small changes, and one showstopper fixed in the nick of
759time made it necessary to release another release candidate. The list
760here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000761
Guido van Rossum5b08f132001-04-16 02:05:23 +0000762Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000763
Guido van Rossum5b08f132001-04-16 02:05:23 +0000764- Tim discovered a nasty bug in the dictionary code, caused by
765 PyDict_Next() calling dict_resize(), and the GC code's use of
766 PyDict_Next() violating an assumption in dict_items(). This was
767 fixed with considerable amounts of band-aid, but the net effect is a
768 saner and more robust implementation.
769
770- Made a bunch of symbols static that were accidentally global.
771
772Build and Ports
773
774- The setup.py script didn't check for a new enough version of zlib
775 (1.1.3 is needed). Now it does.
776
777- Changed "make clean" target to also remove shared libraries.
778
779- Added a more general warning about the SGI Irix optimizer to README.
780
781Library
782
783- Fix a bug in urllib.basejoin("http://host", "../file.html") which
784 omitted the slash between host and file.html.
785
786- The mailbox module's _Mailbox class contained a completely broken
787 and undocumented seek() method. Ripped it out.
788
789- Fixed a bunch of typos in various library modules (urllib2, smtpd,
790 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
791
792- Fixed a few last-minute bugs in unittest.
793
794Extensions
795
796- Reverted the patch to the OpenSSL code in socketmodule.c to support
797 RAND_status() and the EGD, and the subsequent patch that tried to
798 fix it for pre-0.9.5 versions; the problem with the patch is that on
799 some systems it issues a warning whenever socket is imported, and
800 that's unacceptable.
801
802Tests
803
804- Fixed the pickle tests to work with "import test.test_pickle".
805
806- Tweaked test_locale.py to actually run the test Windows.
807
808- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
809 not "wb" (which is not a valid mode at all).
810
811- Fix pstats browser crashes. Import readline if it exists to make
812 the user interface nicer.
813
814- Add "import thread" to the top of test modules that import the
815 threading module (test_asynchat and test_threadedtempfile). This
816 prevents test failures caused by a broken threading module resulting
817 from a previously caught failed import.
818
819- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
820 needed on some platforms (e.g. Solaris 8) when the tests are run
821 twice in succession.
822
823- Skip rather than fail test_sunaudiodev if no audio device is found.
824
825
826What's New in Python 2.1c1?
827===========================
828
829This list was significantly updated when 2.1c2 was released; the 2.1c1
830release didn't mention most changes that were actually part of 2.1c1:
831
832Legal
833
834- Copyright was assigned to the Python Software Foundation (PSF) and a
835 PSF license (very similar to the CNRI license) was added.
836
837- The CNRI copyright notice was updated to include 2001.
838
839Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000840
Guido van Rossumc9932722001-04-12 02:31:27 +0000841- After a public outcry, assignment to __debug__ is no longer illegal;
842 instead, a warning is issued. It will become illegal in 2.2.
843
Guido van Rossum5b08f132001-04-16 02:05:23 +0000844- Fixed a core dump with "%#x" % 0, and changed the semantics so that
845 "%#x" now always prepends "0x", even if the value is zero.
846
847- Fixed some nits in the bytecode compiler.
848
849- Fixed core dumps when calling certain kinds of non-functions.
850
851- Fixed various core dumps caused by reference count bugs.
852
853Build and Ports
854
855- Use INSTALL_SCRIPT to install script files.
856
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000857- New port: SCO Unixware 7, by Billy G. Allie.
858
Guido van Rossum5b08f132001-04-16 02:05:23 +0000859- Updated RISCOS port.
860
861- Updated BeOS port and notes.
862
863- Various other porting problems resolved.
864
865Library
866
867- The TERMIOS and SOCKET modules are now truly obsolete and
868 unnecessary. Their symbols are incorporated in the termios and
869 socket modules.
870
871- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
872 better tests for pickling.
873
874- threading: make Condition.wait() robust against KeyboardInterrupt.
875
876- zipfile: add support to zipfile to support opening an archive
877 represented by an open file rather than a file name. Fix bug where
878 the archive was not properly closed. Fixed a bug in this bugfix
879 where flush() was called for a read-only file.
880
881- imputil: added an uninstall() method to the ImportManager.
882
883- Canvas: fixed bugs in lower() and tkraise() methods.
884
885- SocketServer: API change (added overridable close_request() method)
886 so that the TCP server can explicitly close the request.
887
888- pstats: Eric Raymond added a simple interactive statistics browser,
889 invoked when the module is run as a script.
890
891- locale: fixed a problem in format().
892
893- webbrowser: made it work when the BROWSER environment variable has a
894 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
895 KDE 2. Fixed some other nits.
896
897- unittest: changes to allow using a different exception than
898 AssertionError, and added a few more function aliases. Some other
899 small changes.
900
901- urllib, urllib2: fixed redirect problems and a coupleof other nits.
902
903- asynchat: fixed a critical bug in asynchat that slipped through the
904 2.1b2 release. Fixed another rare bug.
905
906- Fix some unqualified except: clauses (always a bad code example).
907
908XML
909
910- pyexpat: new API get_version_string().
911
912- Fixed some minidom bugs.
913
914Extensions
915
916- Fixed a core dump in _weakref. Removed the weakref.mapping()
917 function (it adds nothing to the API).
918
919- Rationalized the use of header files in the readline module, to make
920 it compile (albeit with some warnings) with the very recent readline
921 4.2, without breaking for earlier versions.
922
923- Hopefully fixed a buffering problem in linuxaudiodev.
924
925- Attempted a fix to make the OpenSSL support in the socket module
926 work again with pre-0.9.5 versions of OpenSSL.
927
928Tests
929
930- Added a test case for asynchat and asyncore.
931
932- Removed coupling between tests where one test failing could break
933 another.
934
935Tools
936
937- Ping added an interactive help browser to pydoc, fixed some nits
938 in the rest of the pydoc code, and added some features to his
939 inspect module.
940
941- An updated python-mode.el version 4.1 which integrates Ken
942 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
943 much nicer in XEmacs and Emacs. When stepping through your program
944 with pdb, in either the shell window or the *Python* window, the
945 source file and line will be tracked by an arrow. Very cool!
946
947- IDLE: syntax warnings in interactive mode are changed into errors.
948
949- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +0000950 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +0000951
952- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000953
Barry Warsaw11e89c72001-04-11 20:37:57 +0000954
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000955What's New in Python 2.1 beta 2?
956================================
957
Guido van Rossum053ae352001-03-22 14:17:21 +0000958(Unlisted are many fixed bugs, more documentation, etc.)
959
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000960Core language, builtins, and interpreter
961
Guido van Rossum053ae352001-03-22 14:17:21 +0000962- The nested scopes work (enabled by "from __future__ import
963 nested_scopes") is completed; in particular, the future now extends
964 into code executed through exec, eval() and execfile(), and into the
965 interactive interpreter.
966
967- When calling a base class method (e.g. BaseClass.__init__(self)),
968 this is now allowed even if self is not strictly spoken a class
969 instance (e.g. when using metaclasses or the Don Beaudry hook).
970
971- Slice objects are now comparable but not hashable; this prevents
972 dict[:] from being accepted but meaningless.
973
974- Complex division is now calculated using less braindead algorithms.
975 This doesn't change semantics except it's more likely to give useful
976 results in extreme cases. Complex repr() now uses full precision
977 like float repr().
978
979- sgmllib.py now calls handle_decl() for simple <!...> declarations.
980
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000981- It is illegal to assign to the name __debug__, which is set when the
982 interpreter starts. It is effectively a compile-time constant.
983
984- A warning will be issued if a global statement for a variable
985 follows a use or assignment of that variable.
986
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000987Standard library
988
Guido van Rossum053ae352001-03-22 14:17:21 +0000989- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
990 inspired by JUnit), is now part of the standard library. You now
991 have a choice of two testing frameworks: unittest requires you to
992 write testcases as separate code, doctest gathers them from
993 docstrings. Both approaches have their advantages and
994 disadvantages.
995
996- A new module Tix was added, which wraps the Tix extension library
997 for Tk. With that module, it is not necessary to statically link
998 Tix with _tkinter, since Tix will be loaded with Tcl's "package
999 require" command. See Demo/tix/.
1000
1001- tzparse.py is now obsolete.
1002
1003- In gzip.py, the seek() and tell() methods are removed -- they were
1004 non-functional anyway, and it's better if callers can test for their
1005 existence with hasattr().
1006
1007Python/C API
1008
1009- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
1010 that's already in the dictionary during a PyDict_Next() iteration.
1011 This used to fail occasionally when a dictionary resize operation
1012 could be triggered that would rehash all the keys. All other
1013 modifications to the dictionary are still off-limits during a
1014 PyDict_Next() iteration!
1015
1016- New extended APIs related to passing compiler variables around.
1017
1018- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
1019 implement isinstance() and issubclass().
1020
1021- Py_BuildValue() now has a "D" conversion to create a Python complex
1022 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +00001023
Fred Drake4e262a92001-03-22 18:26:47 +00001024- Extensions types which support weak references must now set the
1025 field allocated for the weak reference machinery to NULL themselves;
1026 this is done to avoid the cost of checking each object for having a
1027 weakly referencable type in PyObject_INIT(), since most types are
1028 not weakly referencable.
1029
Jeremy Hyltonf626db72001-03-23 14:18:27 +00001030- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
1031 free variables and cell variables to and from the frame's f_locals.
1032
1033- Variants of several functions defined in pythonrun.h have been added
1034 to support the nested_scopes future statement. The variants all end
1035 in Flags and take an extra argument, a PyCompilerFlags *; examples:
1036 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
1037 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +00001038 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +00001039
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001040Distutils
1041
1042- the sdist command now writes a PKG-INFO file, as described in PEP 241,
1043 into the release tree.
1044
Tim Peters0e57abf2001-05-02 07:39:38 +00001045- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001046 (an uninstaller, more customization of the installer's display)
1047
1048- from Jack Jansen: added Mac-specific code to generate a dialog for
1049 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +00001050 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001051 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +00001052
1053- added 'platforms' and 'keywords' to the set of metadata that can be
1054 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001055
1056- applied patches from Jason Tishler to make the compiler class work with
1057 Cygwin.
1058
1059
Tim Peters2fe289a2001-03-01 22:19:38 +00001060What's New in Python 2.1 beta 1?
1061================================
Tim Petersd66595f2001-02-04 03:09:53 +00001062
1063Core language, builtins, and interpreter
1064
Guido van Rossum9d0fbde2001-03-02 14:00:32 +00001065- Following an outcry from the community about the amount of code
1066 broken by the nested scopes feature introduced in 2.1a2, we decided
1067 to make this feature optional, and to wait until Python 2.2 (or at
1068 least 6 months) to make it standard. The option can be enabled on a
1069 per-module basis by adding "from __future__ import nested_scopes" at
1070 the beginning of a module (before any other statements, but after
1071 comments and an optional docstring). See PEP 236 (Back to the
1072 __future__) for a description of the __future__ statement. PEP 227
1073 (Statically Nested Scopes) has been updated to reflect this change,
1074 and to clarify the semantics in a number of endcases.
1075
1076- The nested scopes code, when enabled, has been hardened, and most
1077 bugs and memory leaks in it have been fixed.
1078
1079- Compile-time warnings are now generated for a number of conditions
1080 that will break or change in meaning when nested scopes are enabled:
1081
1082 - Using "from...import *" or "exec" without in-clause in a function
1083 scope that also defines a lambda or nested function with one or
1084 more free (non-local) variables. The presence of the import* or
1085 bare exec makes it impossible for the compiler to determine the
1086 exact set of local variables in the outer scope, which makes it
1087 impossible to determine the bindings for free variables in the
1088 inner scope. To avoid the warning about import *, change it into
1089 an import of explicitly name object, or move the import* statement
1090 to the global scope; to avoid the warning about bare exec, use
1091 exec...in... (a good idea anyway -- there's a possibility that
1092 bare exec will be deprecated in the future).
1093
1094 - Use of a global variable in a nested scope with the same name as a
1095 local variable in a surrounding scope. This will change in
1096 meaning with nested scopes: the name in the inner scope will
1097 reference the variable in the outer scope rather than the global
1098 of the same name. To avoid the warning, either rename the outer
1099 variable, or use a global statement in the inner function.
1100
Neil Schemenauera35c6882001-02-27 04:45:05 +00001101- An optional object allocator has been included. This allocator is
1102 optimized for Python objects and should be faster and use less memory
1103 than the standard system allocator. It is not enabled by default
1104 because of possible thread safety problems. The allocator is only
1105 protected by the Python interpreter lock and it is possible that some
1106 extension modules require a thread safe allocator. The object
1107 allocator can be enabled by providing the "--with-pymalloc" option to
1108 configure.
1109
Tim Petersd66595f2001-02-04 03:09:53 +00001110Standard library
1111
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001112- pyexpat now detects the expat version if expat.h defines it. A
1113 number of additional handlers are provided, which are only available
1114 since expat 1.95. In addition, the methods SetParamEntityParsing and
1115 GetInputContext of Parser objects are available with 1.95.x
1116 only. Parser objects now provide the ordered_attributes and
1117 specified_attributes attributes. A new module expat.model was added,
1118 which offers a number of additional constants if 1.95.x is used.
1119
1120- xml.dom offers the new functions registerDOMImplementation and
1121 getDOMImplementation.
1122
1123- xml.dom.minidom offers a toprettyxml method. A number of DOM
1124 conformance issues have been resolved. In particular, Element now
1125 has an hasAttributes method, and the handling of namespaces was
1126 improved.
1127
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +00001128- Ka-Ping Yee contributed two new modules: inspect.py, a module for
1129 getting information about live Python code, and pydoc.py, a module
1130 for interactively converting docstrings to HTML or text.
1131 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +00001132 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +00001133 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
1134 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +00001135
Tim Peters1eff7962001-03-01 02:31:33 +00001136- New library module difflib.py, primarily packaging the SequenceMatcher
1137 class at the heart of the popular ndiff.py file-comparison tool.
1138
1139- doctest.py (a framework for verifying Python code examples in docstrings)
1140 is now part of the std library.
1141
Tim Petersd66595f2001-02-04 03:09:53 +00001142Windows changes
1143
Guido van Rossume3955a82001-03-02 14:05:59 +00001144- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
1145 small GUI that lets you browse the module docstrings using your
1146 default web browser.
1147
Tim Peters1eff7962001-03-01 02:31:33 +00001148- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
1149 Platforms) is implemented. See
1150
1151 http://python.sourceforge.net/peps/pep-0235.html
1152
1153 for full details, especially the "Current Lower-Left Semantics" section.
1154 The new Windows import rules are simpler than before:
1155
1156 A. If the PYTHONCASEOK environment variable exists, same as
1157 before: silently accept the first case-insensitive match of any
1158 kind; raise ImportError if none found.
1159
1160 B. Else search sys.path for the first case-sensitive match; raise
1161 ImportError if none found.
1162
1163 The same rules have been implented on other platforms with case-
1164 insensitive but case-preserving filesystems too (including Cygwin, and
1165 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +00001166
Tim Peters25a9ce32001-02-19 07:06:36 +00001167- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
1168 what it's supposed to do (and does do under NT and 2000) via direct
1169 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +00001170 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +00001171 all Win9x systems before.
1172
Tim Peters1eff7962001-03-01 02:31:33 +00001173- Build: Subproject _test (effectively) renamed to _testcapi.
1174
Tim Peters2fe289a2001-03-01 22:19:38 +00001175New platforms
1176
1177- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
1178 Thanks to Steven Majewski!
1179
1180- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
1181 Tishler!
1182
Guido van Rossum9089b272001-03-02 06:49:50 +00001183- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
1184 Schwertberger! See RISCOS/README for more information -- it seems
1185 that because of the bizarre filename conventions on RISCOS, no port
1186 to that platform is easy. Note that the new variable os.endsep is
1187 silently supported in order to make life easier on this platform,
1188 but we don't advertise it because it's not worth for most folks to
1189 care about RISCOS portability.
1190
Tim Peters25a9ce32001-02-19 07:06:36 +00001191
Tim Petersd7b5e882001-01-25 03:36:26 +00001192What's New in Python 2.1 alpha 2?
1193=================================
Tim Peters40ead762001-01-27 05:35:26 +00001194
Tim Petersd7b5e882001-01-25 03:36:26 +00001195Core language, builtins, and interpreter
1196
Jeremy Hylton4589bd82001-02-01 20:38:45 +00001197- Scopes nest. If a name is used in a function or class, but is not
1198 local, the definition in the nearest enclosing function scope will
1199 be used. One consequence of this change is that lambda statements
1200 could reference variables in the namespaces where the lambda is
1201 defined. In some unusual cases, this change will break code.
1202
1203 In all previous version of Python, names were resolved in exactly
1204 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001205 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +00001206 function A is defined within a function B, the names bound in B are
1207 not visible in A. The new rules make names bound in B visible in A,
1208 unless A contains a name binding that hides the binding in B.
1209
1210 Section 4.1 of the reference manual describes the new scoping rules
1211 in detail. The test script in Lib/test/test_scope.py demonstrates
1212 some of the effects of the change.
1213
1214 The new rules will cause existing code to break if it defines nested
1215 functions where an outer function has local variables with the same
1216 name as globals or builtins used by the inner function. Example:
1217
1218 def munge(str):
1219 def helper(x):
1220 return str(x)
1221 if type(str) != type(''):
1222 str = helper(str)
1223 return str.strip()
1224
1225 Under the old rules, the name str in helper() is bound to the
1226 builtin function str(). Under the new rules, it will be bound to
1227 the argument named str and an error will occur when helper() is
1228 called.
1229
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001230- The compiler will report a SyntaxError if "from ... import *" occurs
1231 in a function or class scope. The language reference has documented
1232 that this case is illegal, but the compiler never checked for it.
1233 The recent introduction of nested scope makes the meaning of this
1234 form of name binding ambiguous. In a future release, the compiler
1235 may allow this form when there is no possibility of ambiguity.
1236
Tim Peters40ead762001-01-27 05:35:26 +00001237- repr(string) is easier to read, now using hex escapes instead of octal,
1238 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
1239
1240 >>> "\texample \r\n" + chr(0) + chr(255)
1241 '\texample \r\n\x00\xff' # in 2.1
1242 '\011example \015\012\000\377' # in 2.0
1243
Moshe Zadka6af0ce02001-01-29 06:41:00 +00001244- Functions are now compared and hashed by identity, not by value, since
1245 the func_code attribute is writable.
1246
Fred Drakefb9d7122001-02-01 20:00:40 +00001247- Weak references (PEP 205) have been added. This involves a few
1248 changes in the core, an extension module (_weakref), and a Python
1249 module (weakref). The weakref module is the public interface. It
1250 includes support for "explicit" weak references, proxy objects, and
1251 mappings with weakly held values.
1252
Jeremy Hylton0072d5a2001-02-01 22:53:15 +00001253- A 'continue' statement can now appear in a try block within the body
1254 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +00001255 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +00001256
Tim Petersd7b5e882001-01-25 03:36:26 +00001257Standard library
1258
Barry Warsaw30dbd142001-01-31 22:14:01 +00001259- mailbox.py now has a new class, PortableUnixMailbox which is
1260 identical to UnixMailbox but uses a more portable scheme for
1261 determining From_ separators. Also, the constructors for all the
1262 classes in this module have a new optional `factory' argument, which
1263 is a callable used when new message classes must be instantiated by
1264 the next() method.
1265
Tim Petersd7b5e882001-01-25 03:36:26 +00001266- random.py is now self-contained, and offers all the functionality of
1267 the now-deprecated whrandom.py. See the docs for details. random.py
1268 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +00001269 and restoring the internal state of the generator; and jumpahead(n),
1270 for quickly forcing the internal state to be the same as if n calls to
1271 random() had been made. The latter is particularly useful for multi-
1272 threaded programs, creating one instance of the random.Random() class for
1273 each thread, then using .jumpahead() to force each instance to use a
1274 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +00001275
Tim Peters0de88fc2001-02-01 04:59:18 +00001276- random.py's seed() function is new. For bit-for-bit compatibility with
1277 prior releases, use the whseed function instead. The new seed function
1278 addresses two problems: (1) The old function couldn't produce more than
1279 about 2**24 distinct internal states; the new one about 2**45 (the best
1280 that can be done in the Wichmann-Hill generator). (2) The old function
1281 sometimes produced identical internal states when passed distinct
1282 integers, and there was no simple way to predict when that would happen;
1283 the new one guarantees to produce distinct internal states for all
1284 arguments in [0, 27814431486576L).
1285
Jeremy Hylton4c4fda02001-02-02 03:29:24 +00001286- The socket module now supports raw packets on Linux. The socket
1287 family is AF_PACKET.
1288
Tim Peters9ea17ac2001-02-02 05:57:15 +00001289- test_capi.py is a start at running tests of the Python C API. The tests
1290 are implemented by the new Modules/_testmodule.c.
1291
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001292- A new extension module, _symtable, provides provisional access to the
1293 internal symbol table used by the Python compiler. A higher-level
1294 interface will be added on top of _symtable in a future release.
1295
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +00001296- Removed the obsolete soundex module.
1297
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001298- xml.dom.minidom now uses the standard DOM exceptions. Node supports
1299 the isSameNode method; NamedNodeMap the get method.
1300
1301- xml.sax.expatreader supports the lexical handler property; it
1302 generates comment, startCDATA, and endCDATA events.
1303
Tim Petersee826f82001-01-31 19:39:44 +00001304Windows changes
1305
1306- Build procedure: the zlib project is built in a different way that
1307 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +00001308 the zlib binary used. See PCbuild\readme.txt for details. Your old
1309 zlib-related directories can be deleted; you'll need to download fresh
1310 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +00001311
Tim Peters9ea17ac2001-02-02 05:57:15 +00001312- Build: New subproject _test for the benefit of test_capi.py (see above).
1313
Tim Petersb16c56f2001-02-02 21:24:51 +00001314- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
1315 interface to some Python compiler internals).
1316
1317- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +00001318 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +00001319
Tim Petersa3a3a032000-11-30 05:22:44 +00001320What's New in Python 2.1 alpha 1?
1321=================================
1322
1323Core language, builtins, and interpreter
1324
Marc-André Lemburgebb195b2001-01-20 10:34:52 +00001325- There is a new Unicode companion to the PyObject_Str() API
1326 called PyObject_Unicode(). It behaves in the same way as the
1327 former, but assures that the returned value is an Unicode object
1328 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +00001329
Guido van Rossumf98eda02001-01-17 15:54:45 +00001330- The comparison operators support "rich comparison overloading" (PEP
1331 207). C extension types can provide a rich comparison function in
1332 the new tp_richcompare slot in the type object. The cmp() function
1333 and the C function PyObject_Compare() first try the new rich
1334 comparison operators before trying the old 3-way comparison. There
1335 is also a new C API PyObject_RichCompare() (which also falls back on
1336 the old 3-way comparison, but does not constrain the outcome of the
1337 rich comparison to a Boolean result).
1338
1339 The rich comparison function takes two objects (at least one of
1340 which is guaranteed to have the type that provided the function) and
1341 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
1342 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
1343 object, which may be NotImplemented (in which case the tp_compare
1344 slot function is used as a fallback, if defined).
1345
1346 Classes can overload individual comparison operators by defining one
1347 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +00001348 __ge__. There are no explicit "reflected argument" versions of
1349 these; instead, __lt__ and __gt__ are each other's reflection,
1350 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
1351 reflection (similar at the C level). No other implications are
1352 made; in particular, Python does not assume that == is the Boolean
1353 inverse of !=, or that < is the Boolean inverse of >=. This makes
1354 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +00001355
1356 Classes or types that want to implement (in)equality tests but not
1357 the ordering operators (i.e. unordered types) should implement ==
1358 and !=, and raise an error for the ordering operators.
1359
Guido van Rossuma88479f2001-01-18 14:28:08 +00001360 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +00001361 Boolean; e.g. a matrix type might want to return a matrix of bits
1362 for A < B, giving elementwise comparisons. Such types should ensure
1363 that any interpretation of their value in a Boolean context raises
1364 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
1365 at the C level) to always raise an exception.
1366
Guido van Rossuma88479f2001-01-18 14:28:08 +00001367- Complex numbers use rich comparisons to define == and != but raise
1368 an exception for <, <=, > and >=. Unfortunately, this also means
1369 that cmp() of two complex numbers raises an exception when the two
1370 numbers differ. Since it is not mathematically meaningful to compare
1371 complex numbers except for equality, I hope that this doesn't break
1372 too much code.
1373
Tim Peters3389f192001-02-18 08:48:49 +00001374- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +00001375 not defined by the language, other than that it's arbitrary but
1376 consistent (see the Reference Manual). An implementation detail changed
1377 in 2.1a1 such that None now compares less than any other object. Code
1378 relying on this new behavior (like code that relied on the previous
1379 behavior) does so at its own risk.
1380
Barry Warsaw573b5412001-01-15 20:43:18 +00001381- Functions and methods now support getting and setting arbitrarily
1382 named attributes (PEP 232). Functions have a new __dict__
1383 (a.k.a. func_dict) which hold the function attributes. Methods get
1384 and set attributes on their underlying im_func. It is a TypeError
1385 to set an attribute on a bound method.
1386
Guido van Rossum051e3352001-01-15 19:11:10 +00001387- The xrange() object implementation has been improved so that
1388 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1389 limitation that in this case len(xrange(sys.maxint)) can't be
1390 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1391 work fine as long as the index i doesn't actually reach 2**31.
1392 (Python uses regular ints for sequence and string indices; fixing
1393 that is much more work.)
1394
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001395- Two changes to from...import:
1396
Guido van Rossumba381232001-02-03 15:06:40 +00001397 1) "from M import X" now works even if (after loading module M)
1398 sys.modules['M'] is not a real module; it's basically a getattr()
1399 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001400
1401 2) "from M import *" now looks for M.__all__ to decide which names to
1402 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1403 filters out names starting with '_' as before. Whether or not
1404 __all__ exists, there's no restriction on the type of M.
1405
Guido van Rossumf61f1662001-01-10 20:13:55 +00001406- File objects have a new method, xreadlines(). This is the fastest
1407 way to iterate over all lines in a file:
1408
1409 for line in file.xreadlines():
1410 ...do something to line...
1411
1412 See the xreadlines module (mentioned below) for how to do this for
1413 other file-like objects.
1414
1415- Even if you don't use file.xreadlines(), you may expect a speedup on
1416 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001417 quite a bit in platform-specific ways: on systems (like Linux) that
1418 support flockfile(), getc_unlocked(), and funlockfile(), those are
1419 used by default. On systems (like Windows) without getc_unlocked(),
1420 a complicated (but still thread-safe) method using fgets() is used by
1421 default.
1422
Tim Petersd52269b2001-01-25 06:23:18 +00001423 You can force use of the fgets() method by #define'ing
1424 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001425 getc_unlocked()).
1426
Tim Petersd52269b2001-01-25 06:23:18 +00001427 You can force fgets() not to be used by #define'ing
1428 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001429 test_bufio.py fails -- and let us know if it does!).
1430
1431- In addition, the fileinput module, while still slower than the other
1432 methods on most platforms, has been sped up too, by using
1433 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001434
1435- Support for run-time warnings has been added, including a new
1436 command line option (-W) to specify the disposition of warnings.
1437 See the description of the warnings module below.
1438
1439- Extensive changes have been made to the coercion code. This mostly
1440 affects extension modules (which can now implement mixed-type
1441 numerical operators without having to use coercion), but
1442 occasionally, in boundary cases the coercion semantics have changed
1443 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001444 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001445 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001446 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001447
Guido van Rossumf98eda02001-01-17 15:54:45 +00001448- In connection with the coercion changes, a new built-in singleton
1449 object, NotImplemented is defined. This can be returned for
1450 operations that wish to indicate they are not implemented for a
1451 particular combination of arguments. From C, this is
1452 Py_NotImplemented.
1453
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001454- The interpreter accepts now bytecode files on the command line even
1455 if they do not have a .pyc or .pyo extension. On Linux, after executing
1456
Martin v. Löwise214baa2001-02-04 22:37:56 +00001457import imp,sys,string
1458magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1459reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1460open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001461
1462 any byte code file can be used as an executable (i.e. as an argument
1463 to execve(2)).
1464
Tim Peters9940b802000-12-01 07:59:35 +00001465- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001466 character. In 1.6 and earlier, they never produced a sign,
1467 and raised an error if the value of the long was too large
1468 to fit in a Python int. In 2.0, they produced a sign if and
1469 only if too large to fit in an int. This was inconsistent
1470 across platforms (because the size of an int varies across
1471 platforms), and inconsistent with hex() and oct(). Example:
1472
1473 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001474 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001475 'ffffffbe' # in 2.0 and before, on 32-bit machines
1476 >>> hex(-0x42L)
1477 '-0x42L' # in all versions of Python
1478
Tim Peters9940b802000-12-01 07:59:35 +00001479 The behavior of %d formats for negative Python longs remains
1480 the same as in 2.0 (although in 1.6 and before, they raised
1481 an error if the long didn't fit in a Python int).
1482
1483 %u formats don't make sense for Python longs, but are allowed
1484 and treated the same as %d in 2.1. In 2.0, a negative long
1485 formatted via %u produced a sign if and only if too large to
1486 fit in an int. In 1.6 and earlier, a negative long formatted
1487 via %u raised an error if it was too big to fit in an int.
1488
Guido van Rossum3661d392000-12-12 22:10:31 +00001489- Dictionary objects have an odd new method, popitem(). This removes
1490 an arbitrary item from the dictionary and returns it (in the form of
1491 a (key, value) pair). This can be useful for algorithms that use a
1492 dictionary as a bag of "to do" items and repeatedly need to pick one
1493 item. Such algorithms normally end up running in quadratic time;
1494 using popitem() they can usually be made to run in linear time.
1495
Tim Peters36cdad12000-12-29 02:06:45 +00001496Standard library
1497
Thomas Woutersfe385252001-01-19 23:16:56 +00001498- In the time module, the time argument to the functions strftime,
1499 localtime, gmtime, asctime and ctime is now optional, defaulting to
1500 the current time (in the local timezone).
1501
Guido van Rossumda91f222001-01-15 16:36:08 +00001502- The ftplib module now defaults to passive mode, which is deemed a
1503 more useful default given that clients are often inside firewalls
1504 these days. Note that this could break if ftplib is used to connect
1505 to a *server* that is inside a firewall, from outside; this is
1506 expected to be a very rare situation. To fix that, you can call
1507 ftp.set_pasv(0).
1508
Martin v. Löwis10a27872001-01-13 09:54:41 +00001509- The module site now treats .pth files not only for path configuration,
1510 but also supports extensions to the initialization code: Lines starting
1511 with import are executed.
1512
Guido van Rossumf61f1662001-01-10 20:13:55 +00001513- There's a new module, warnings, which implements a mechanism for
1514 issuing and filtering warnings. There are some new built-in
1515 exceptions that serve as warning categories, and a new command line
1516 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1517 turns warnings into errors). warnings.warn(message[, category])
1518 issues a warning message; this can also be called from C as
1519 PyErr_Warn(category, message).
1520
1521- A new module xreadlines was added. This exports a single factory
1522 function, xreadlines(). The intention is that this code is the
1523 absolutely fastest way to iterate over all lines in an open
1524 file(-like) object:
1525
1526 import xreadlines
1527 for line in xreadlines.xreadlines(file):
1528 ...do something to line...
1529
1530 This is equivalent to the previous the speed record holder using
1531 file.readlines(sizehint). Note that if file is a real file object
1532 (as opposed to a file-like object), this is equivalent:
1533
1534 for line in file.xreadlines():
1535 ...do something to line...
1536
Tim Peters36cdad12000-12-29 02:06:45 +00001537- The bisect module has new functions bisect_left, insort_left,
1538 bisect_right and insort_right. The old names bisect and insort
1539 are now aliases for bisect_right and insort_right. XXX_right
1540 and XXX_left methods differ in what happens when the new element
1541 compares equal to one or more elements already in the list: the
1542 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001543 right. Code that doesn't care where equal elements end up should
1544 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001545
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001546- The new curses.panel module wraps the panel library that forms part
1547 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1548
Guido van Rossumf61f1662001-01-10 20:13:55 +00001549- The SocketServer module now sets the allow_reuse_address flag by
1550 default in the TCPServer class.
1551
1552- A new function, sys._getframe(), returns the stack frame pointer of
1553 the caller. This is intended only as a building block for
1554 higher-level mechanisms such as string interpolation.
1555
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001556- The pyexpat module supports a number of new handlers, which are
1557 available only in expat 1.2. If invocation of a callback fails, it
1558 will report an additional frame in the traceback. Parser objects
1559 participate now in garbage collection. If expat reports an unknown
1560 encoding, pyexpat will try to use a Python codec; that works only
1561 for single-byte charsets. The parser type objects is exposed as
1562 XMLParserObject.
1563
1564- xml.dom now offers standard definitions for symbolic node type and
1565 exception code constants, and a hierarchy of DOM exceptions. minidom
1566 was adjusted to use them.
1567
1568- The conformance of xml.dom.minidom to the DOM specification was
1569 improved. It detects a number of additional error cases; the
1570 previous/next relationship works even when the tree is modified;
1571 Node supports the normalize() method; NamedNodeMap, DocumentType and
1572 DOMImplementation classes were added; Element supports the
1573 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1574 method.
1575
Guido van Rossumf61f1662001-01-10 20:13:55 +00001576Build issues
1577
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001578- For Unix (and Unix-compatible) builds, configuration and building of
1579 extension modules is now greatly automated. Rather than having to
1580 edit the Modules/Setup file to indicate which modules should be
1581 built and where their include files and libraries are, a
1582 distutils-based setup.py script now takes care of building most
1583 extension modules. All extension modules built this way are built
1584 as shared libraries. Only a few modules that must be linked
1585 statically are still listed in the Setup file; you won't need to
1586 edit their configuration.
1587
1588- Python should now build out of the box on Cygwin. If it doesn't,
1589 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001590
1591- Python now always uses its own (renamed) implementation of getopt()
1592 -- there's too much variation among C library getopt()
1593 implementations.
1594
1595- C++ compilers are better supported; the CXX macro is always set to a
1596 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001597
Tim Petersd92dfe02000-12-12 01:18:41 +00001598Windows changes
1599
1600- select module: By default under Windows, a select() call
1601 can specify no more than 64 sockets. Python now boosts
1602 this Microsoft default to 512. If you need even more than
1603 that, see the MS docs (you'll need to #define FD_SETSIZE
1604 and recompile Python from source).
1605
Guido van Rossumf61f1662001-01-10 20:13:55 +00001606- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1607 subdirectory is no more!
1608
Tim Petersa3a3a032000-11-30 05:22:44 +00001609
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001610What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001611=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001612
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001613Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001614changes are in the file HISTORY. If you are making the jump directly
1615from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1616HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001617
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001618Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1619the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1620http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001621
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001622--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001623
1624======================================================================
1625
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001626What's new in 2.0 (since release candidate 1)?
1627==============================================
1628
1629Standard library
1630
1631- The copy_reg module was modified to clarify its intended use: to
1632 register pickle support for extension types, not for classes.
1633 pickle() will raise a TypeError if it is passed a class.
1634
1635- Fixed a bug in gettext's "normalize and expand" code that prevented
1636 it from finding an existing .mo file.
1637
1638- Restored support for HTTP/0.9 servers in httplib.
1639
Tim Peters989b7b92000-10-16 20:24:53 +00001640- The math module was changed to stop raising OverflowError in case of
1641 underflow, and return 0 instead in underflow cases. Whether Python
1642 used to raise OverflowError in case of underflow was platform-
1643 dependent (it did when the platform math library set errno to ERANGE
1644 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001645
1646- Fixed a bug in StringIO that occurred when the file position was not
1647 at the end of the file and write() was called with enough data to
1648 extend past the end of the file.
1649
1650- Fixed a bug that caused Tkinter error messages to get lost on
1651 Windows. The bug was fixed by replacing direct use of
1652 interp->result with Tcl_GetStringResult(interp).
1653
1654- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1655 redirect response.
1656
1657- Several changes were made to distutils: Some debugging code was
1658 removed from util. Fixed the installer used when an external zip
1659 program (like WinZip) is not found; the source code for this
1660 installer is in Misc/distutils. check_lib() was modified to behave
1661 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1662 test for whether installed modules are on sys.path was changed to
1663 use both normcase() and normpath().
1664
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001665- Several minor bugs were fixed in the xml package (the minidom,
1666 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001667
1668- The regression test driver (regrtest.py) behavior when invoked with
1669 -l changed: It now reports a count of objects that are recognized as
1670 garbage but not freed by the garbage collector.
1671
Tim Peters989b7b92000-10-16 20:24:53 +00001672- The regression test for the math module was changed to test
1673 exceptional behavior when the test is run in verbose mode. Python
1674 cannot yet guarantee consistent exception behavior across platforms,
1675 so the exception part of test_math is run only in verbose mode, and
1676 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001677
1678Internals
1679
1680- PyOS_CheckStack() has been disabled on Win64, where it caused
1681 test_sre to fail.
1682
1683Build issues
1684
1685- Changed compiler flags, so that gcc is always invoked with -Wall and
1686 -Wstrict-prototypes. Users compiling Python with GCC should see
1687 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001688 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001689 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001690
Tim Petersa3a3a032000-11-30 05:22:44 +00001691- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001692
1693Tools and other miscellany
1694
1695- The compiler in Tools/compiler was updated to support the new
1696 language features introduced in 2.0: extended print statement, list
1697 comprehensions, and augmented assignments. The new compiler should
1698 also be backwards compatible with Python 1.5.2; the compiler will
1699 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001700 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001701
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001702What's new in 2.0 release candidate 1 (since beta 2)?
1703=====================================================
1704
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001705What is release candidate 1?
1706
1707We believe that release candidate 1 will fix all known bugs that we
1708intend to fix for the 2.0 final release. This release should be a bit
1709more stable than the previous betas. We would like to see even more
1710widespread testing before the final release, so we are producing this
1711release candidate. The final release will be exactly the same unless
1712any show-stopping (or brown bag) bugs are found by testers of the
1713release candidate.
1714
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001715All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001716to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001717
1718Core language, builtins, and interpreter
1719
1720- A bug that caused crashes when __coerce__ was used with augmented
1721 assignment, e.g. +=, was fixed.
1722
1723- Raise ZeroDivisionError when raising zero to a negative number,
1724 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1725 power operator and the result of math.pow(0.0, -2.0) will vary by
1726 platform. On Linux, it raises a ValueError.
1727
1728- A bug in Unicode string interpolation was fixed that occasionally
1729 caused errors with formats including "%%". For example, the
1730 following expression "%% %s" % u"abc" no longer raises a TypeError.
1731
1732- Compilation of deeply nested expressions raises MemoryError instead
1733 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1734
1735- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1736 rendering them useless. They are now written in binary mode again.
1737
1738Standard library
1739
1740- Keyword arguments are now accepted for most pattern and match object
1741 methods in SRE, the standard regular expression engine.
1742
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001743- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001744 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001745
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001746- Several bugs in the Unicode handling and error handling in _tkinter
1747 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001748
1749- Fix memory management errors in Merge() and Tkapp_Call() routines.
1750
1751- Several changes were made to cStringIO to make it compatible with
1752 the file-like object interface and with StringIO. If operations are
1753 performed on a closed object, an exception is raised. The truncate
1754 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001755 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001756
1757- There were many changes made to the linuxaudiodev module and its
1758 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001759 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001760
1761 Note that this module is named poorly, because it should work
1762 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001763 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001764
1765 The module now raises exceptions when errors occur instead of
1766 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1767 audio) and defines a getptr() method that calls the
1768 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1769
1770- The library_version attribute, introduced in an earlier beta, was
1771 removed because it can not be supported with early versions of the C
1772 readline library, which provides no way to determine the version at
1773 compile-time.
1774
1775- The binascii module is now enabled on Win64.
1776
Tim Peters46446d62000-10-09 21:19:31 +00001777- tokenize.py no longer suffers "recursion depth" errors when parsing
1778 programs with very long string literals.
1779
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001780Internals
1781
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001782- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001783 which is called when the interpreter starts up to determine where
1784 the standard library is installed. These vulnerabilities affect all
1785 previous versions of Python and can be exploited by setting very
1786 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1787 setuid Python script, although use of the wrapper in
1788 Misc/setuid-prog.c will eliminate the vulnerability.
1789
1790- Fixed garbage collection bugs in instance creation that were
1791 triggered when errors occurred during initialization. The solution,
1792 applied in cPickle and in PyInstance_New(), is to call
1793 PyObject_GC_Init() after the initialization of the object's
1794 container attributes is complete.
1795
1796- pyexpat adds definitions of PyModule_AddStringConstant and
1797 PyModule_AddObject if the Python version is less than 2.0, which
1798 provides compatibility with PyXML on Python 1.5.2.
1799
1800- If the platform has a bogus definition for LONG_BIT (the number of
1801 bits in a long), an error will be reported at compile time.
1802
1803- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1804 collection crashes and possibly other, unreported crashes.
1805
1806- Fixed a memory leak in _PyUnicode_Fini().
1807
1808Build issues
1809
1810- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001811 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001812 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001813
1814- The mmap.PAGESIZE constant is now initialized using sysconf when
1815 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1816
1817- The md5 file should now compile on all platforms.
1818
1819- The select module now compiles on platforms that do not define
1820 POLLRDNORM and related constants.
1821
1822- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001823 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001824
Jeremy Hylton10921202000-10-09 18:34:12 +00001825- BeOS: A number of changes were made to the build and installation
1826 process. ar-fake now operates on a directory of object files.
1827 dl_export.h is gone, and its macros now appear on the mwcc command
1828 line during build on PPC BeOS.
1829
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001830- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001831 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001832
1833- Cygwin: Support for shared libraries, Tkinter, and sockets.
1834
1835- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1836
1837Tools and other miscellany
1838
1839- Removed debugging prints from main used with freeze.
1840
Tim Peters46446d62000-10-09 21:19:31 +00001841- IDLE auto-indent no longer crashes when it encounters Unicode
1842 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001843
1844What's new in 2.0 beta 2 (since beta 1)?
1845========================================
1846
1847Core language, builtins, and interpreter
1848
Tim Peters482c0212000-09-26 06:33:09 +00001849- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001850 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001851
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001852- Add -h and -V command line options to print the usage message and
1853 Python version number and exit immediately.
1854
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001855- eval() and exec accept Unicode objects as code parameters.
1856
1857- getattr() and setattr() now also accept Unicode objects for the
1858 attribute name, which are converted to strings using the default
1859 encoding before lookup.
1860
1861- Multiplication on string and Unicode now does proper bounds
1862 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1863 string is too long."
1864
1865- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001866 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001867
Jeremy Hylton1b618592000-09-26 05:32:36 +00001868
1869Standard library and extensions
1870
Guido van Rossum5b08f132001-04-16 02:05:23 +00001871- socket module: the OpenSSL code now adds support for RAND_status()
1872 and EGD (Entropy Gathering Device).
1873
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001874- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001875 argument checking; it still takes no arguments.
1876
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001877- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001878
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001879- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001880
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001881- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001882
1883- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001884 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001885
1886- copy: Copy Unicode objects atomically.
1887
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001888- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001889
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001890- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001891
Fred Drake67233bc2000-09-26 16:40:27 +00001892- dbm: Add get() and setdefault() methods to dbm object. Add constant
1893 `library' to module that names the library used. Added doc strings
1894 and method names to error messages. Uses configure to determine
1895 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1896 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001897
1898- distutils: Update to version 0.9.3.
1899
1900- dl: Add several dl.RTLD_ constants.
1901
1902- fpectl: Now supported on FreeBSD.
1903
1904- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1905 found by the collector will be saved in gc.garbage. This is useful
1906 for debugging a program that creates reference cycles.
1907
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001908- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001909 of HTTP class. Do not close socket on zero-length response. Do not
1910 crash when server sends invalid content-length header.
1911
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001912- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001913
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001914- marshal: When reading a short, sign-extend on platforms where shorts
1915 are bigger than 16 bits. When reading a long, repair the unportable
1916 sign extension that was being done for 64-bit machines. (It assumed
1917 that signed right shift sign-extends.)
1918
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001919- operator: Add contains(), invert(), __invert__() as aliases for
1920 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001921
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001922- os: Add support for popen2() and popen3() on all platforms where
1923 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001924
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001925- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001926 clicking on a file in Explorer (or passing the file name to the
1927 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001928
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001929- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001930 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001931
1932- pickle: Now raises ValueError when an invalid pickle that contains
1933 a non-string repr where a string repr was expected. This behavior
1934 matches cPickle.
1935
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001936- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001937
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001938- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001939
1940- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001941 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001942 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001943
1944- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001945 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001946
1947- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001948 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001949 few cycles during startup since the first call to
1950 setdefaultencoding() will initialize the codec registry and the
1951 encodings package.
1952
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001953- socket: Support for size hint in readlines() method of object returned
1954 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001955
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001956- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001957 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001958 is followed by whitespace.
1959
Tim Petersa3a3a032000-11-30 05:22:44 +00001960- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001961
1962- struct: Check ranges for bytes and shorts.
1963
1964- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001965 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001966
1967- Tkinter: Image objects are now guaranteed to have unique ids. Set
1968 event.delta to zero if Tk version doesn't support mousewheel.
1969 Removed some debugging prints.
1970
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001971- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001972
Fred Drake67233bc2000-09-26 16:40:27 +00001973- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001974 which works around a bug in Norton AntiVirus 2000 that leads directly
1975 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001976
1977- xml: New version detection code allows PyXML to override standard
1978 XML package if PyXML version is greater than 0.6.1.
1979
Fred Drake64bb3802000-09-26 16:21:35 +00001980- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1981 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1982 tree only for nodes which are sufficiently interesting to a specific
1983 application. Does not provide the HTML-specific extensions. Still
1984 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001985
Fred Drake64bb3802000-09-26 16:21:35 +00001986- xml.sax: SAX 2 support for Python, including all the handler
1987 interfaces needed to process XML 1.0 compliant XML. Some
1988 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001989
Fred Drake64bb3802000-09-26 16:21:35 +00001990- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1991 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001992
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001993
Jeremy Hylton1b618592000-09-26 05:32:36 +00001994C API
1995
1996- Add three new convenience functions for module initialization --
1997 PyModule_AddObject(), PyModule_AddIntConstant(), and
1998 PyModule_AddStringConstant().
1999
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002000- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00002001 removed and add #error to Python.h if NULL isn't defined after
2002 #include of stdio.h.
2003
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002004- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00002005 backwards compatibility (at the source level) with old extensions.
2006
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002007- A wrapper API was added for signal() and sigaction(). Instead of
2008 either function, always use PyOS_getsig() to get a signal handler
2009 and PyOS_setsig() to set one. A new convenience typedef
2010 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002011
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002012- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00002013 internal data buffer and size of a string object -- or the default
2014 encoded version of a Unicode object.
2015
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002016- PyString_Size() and PyString_AsString() accept Unicode objects.
2017
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002018- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00002019 exists). INT_MAX and LONG_MAX will always be defined, even if
2020 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002021
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002022- PyFloat_FromString takes a second argument, pend, that was
2023 effectively useless. It is now officially useless but preserved for
2024 backwards compatibility. If the pend argument is not NULL, *pend is
2025 set to NULL.
2026
2027- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
2028 for the attribute name. See note on getattr() above.
2029
2030- A few bug fixes to argument processing for Unicode.
2031 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
2032 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
2033 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00002034 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002035
2036- Py_BuildValue accepts B format (for bgen-generated code).
2037
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002038
Jeremy Hylton1b618592000-09-26 05:32:36 +00002039Internals
2040
2041- On Unix, fix code for finding Python installation directory so that
2042 it works when argv[0] is a relative path.
2043
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00002044- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002045 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00002046 rather than by generating a copy of the object.
2047
Tim Peters482c0212000-09-26 06:33:09 +00002048- Several of the internal Unicode tables are much smaller now, and
2049 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002050
Jeremy Hylton97693b02000-09-26 17:42:51 +00002051- In the garbage collector: Fixed bug in collection of tuples. Fixed
2052 bug that caused some instances to be removed from the container set
2053 while they were still live. Fixed parsing in gc.set_debug() for
2054 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002055
2056- Fixed refcount problem in instance deallocation that only occurred
2057 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
2058
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002059- On Windows, getpythonregpath is now protected against null data in
2060 registry key.
2061
2062- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00002063 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002064
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002065
Jeremy Hylton1b618592000-09-26 05:32:36 +00002066Build and platform-specific issues
2067
2068- Better support of GNU Pth via --with-pth configure option.
2069
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002070- Python/C API now properly exposed to dynamically-loaded extension
2071 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002072
2073- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
2074 Don't define MS_SYNC to be zero when it is undefined. Added missing
2075 prototypes in posixmodule.c.
2076
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002077- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002078 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00002079
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002080- Fix largefile support on older NetBSD systems and OpenBSD by adding
2081 define for TELL64.
2082
2083
2084Tools and other miscellany
2085
2086- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
2087
2088- freeze: The modulefinder now works with 2.0 opcodes.
2089
Tim Petersa3a3a032000-11-30 05:22:44 +00002090- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002091 Move hackery of sys.argv until after the Tk instance has been
2092 created, which allows the application-specific Tkinter
2093 initialization to be executed if present; also pass an explicit
2094 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00002095
Jeremy Hylton1b618592000-09-26 05:32:36 +00002096
2097What's new in 2.0 beta 1?
2098=========================
2099
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002100Source Incompatibilities
2101------------------------
2102
2103None. Note that 1.6 introduced several incompatibilities with 1.5.2,
2104such as single-argument append(), connect() and bind(), and changes to
2105str(long) and repr(float).
2106
2107
2108Binary Incompatibilities
2109------------------------
2110
2111- Third party extensions built for Python 1.5.x or 1.6 cannot be used
2112with Python 2.0; these extensions will have to be rebuilt for Python
21132.0.
2114
2115- On Windows, attempting to import a third party extension built for
2116Python 1.5.x or 1.6 results in an immediate crash; there's not much we
2117can do about this. Check your PYTHONPATH environment variable!
2118
2119- Python bytecode files (*.pyc and *.pyo) are not compatible between
2120releases.
2121
2122
2123Overview of Changes Since 1.6
2124-----------------------------
2125
2126There are many new modules (including brand new XML support through
2127the xml package, and i18n support through the gettext module); a list
2128of all new modules is included below. Lots of bugs have been fixed.
2129
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002130The process for making major new changes to the language has changed
2131since Python 1.6. Enhancements must now be documented by a Python
2132Enhancement Proposal (PEP) before they can be accepted.
2133
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002134There are several important syntax enhancements, described in more
2135detail below:
2136
2137 - Augmented assignment, e.g. x += 1
2138
2139 - List comprehensions, e.g. [x**2 for x in range(10)]
2140
2141 - Extended import statement, e.g. import Module as Name
2142
2143 - Extended print statement, e.g. print >> file, "Hello"
2144
2145Other important changes:
2146
2147 - Optional collection of cyclical garbage
2148
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002149Python Enhancement Proposal (PEP)
2150---------------------------------
2151
2152PEP stands for Python Enhancement Proposal. A PEP is a design
2153document providing information to the Python community, or describing
2154a new feature for Python. The PEP should provide a concise technical
2155specification of the feature and a rationale for the feature.
2156
2157We intend PEPs to be the primary mechanisms for proposing new
2158features, for collecting community input on an issue, and for
2159documenting the design decisions that have gone into Python. The PEP
2160author is responsible for building consensus within the community and
2161documenting dissenting opinions.
2162
2163The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002164
2165Augmented Assignment
2166--------------------
2167
2168This must have been the most-requested feature of the past years!
2169Eleven new assignment operators were added:
2170
Guido van Rossume905e952000-09-05 12:42:46 +00002171 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002172
2173For example,
2174
2175 A += B
2176
2177is similar to
2178
2179 A = A + B
2180
2181except that A is evaluated only once (relevant when A is something
2182like dict[index].attr).
2183
2184However, if A is a mutable object, A may be modified in place. Thus,
2185if A is a number or a string, A += B has the same effect as A = A+B
2186(except A is only evaluated once); but if a is a list, A += B has the
2187same effect as A.extend(B)!
2188
2189Classes and built-in object types can override the new operators in
2190order to implement the in-place behavior; the not-in-place behavior is
2191used automatically as a fallback when an object doesn't implement the
2192in-place behavior. For classes, the method name is derived from the
2193method name for the corresponding not-in-place operator by inserting
2194an 'i' in front of the name, e.g. __iadd__ implements in-place
2195__add__.
2196
2197Augmented assignment was implemented by Thomas Wouters.
2198
2199
2200List Comprehensions
2201-------------------
2202
2203This is a flexible new notation for lists whose elements are computed
2204from another list (or lists). The simplest form is:
2205
2206 [<expression> for <variable> in <sequence>]
2207
Guido van Rossum56db0952000-09-06 23:34:25 +00002208For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002209This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002210
2211You can also add a condition:
2212
2213 [<expression> for <variable> in <sequence> if <condition>]
2214
2215For example, [w for w in words if w == w.lower()] would yield the list
2216of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002217than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002218
2219You can also have nested for loops and more than one 'if' clause. For
2220example, here's a function that flattens a sequence of sequences::
2221
2222 def flatten(seq):
2223 return [x for subseq in seq for x in subseq]
2224
2225 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
2226
2227This prints
2228
2229 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
2230
2231List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002232Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002233
2234
2235Extended Import Statement
2236-------------------------
2237
2238Many people have asked for a way to import a module under a different
2239name. This can be accomplished like this:
2240
2241 import foo
2242 bar = foo
2243 del foo
2244
2245but this common idiom gets old quickly. A simple extension of the
2246import statement now allows this to be written as follows:
2247
2248 import foo as bar
2249
2250There's also a variant for 'from ... import':
2251
2252 from foo import bar as spam
2253
2254This also works with packages; e.g. you can write this:
2255
2256 import test.regrtest as regrtest
2257
2258Note that 'as' is not a new keyword -- it is recognized only in this
2259context (this is only possible because the syntax for the import
2260statement doesn't involve expressions).
2261
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002262Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002263
2264
2265Extended Print Statement
2266------------------------
2267
2268Easily the most controversial new feature, this extension to the print
2269statement adds an option to make the output go to a different file
2270than the default sys.stdout.
2271
2272For example, to write an error message to sys.stderr, you can now
2273write:
2274
2275 print >> sys.stderr, "Error: bad dog!"
2276
2277As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00002278evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002279
2280 print >> None, "Hello world"
2281
2282is equivalent to
2283
2284 print "Hello world"
2285
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002286Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002287
2288
2289Optional Collection of Cyclical Garbage
2290---------------------------------------
2291
2292Python is now equipped with a garbage collector that can hunt down
2293cyclical references between Python objects. It's no replacement for
2294reference counting; in fact, it depends on the reference counts being
2295correct, and decides that a set of objects belong to a cycle if all
2296their reference counts can be accounted for from their references to
2297each other. This devious scheme was first proposed by Eric Tiedemann,
2298and brought to implementation by Neil Schemenauer.
2299
2300There's a module "gc" that lets you control some parameters of the
2301garbage collection. There's also an option to the configure script
2302that lets you enable or disable the garbage collection. In 2.0b1,
2303it's on by default, so that we (hopefully) can collect decent user
2304experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00002305performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002306off by default in the final 2.0 release.
2307
2308
2309Smaller Changes
2310---------------
2311
2312A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
2313map(None, seq1, seq2, ...) when the sequences have the same length;
2314i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
2315the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002316zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002317
2318sys.version_info is a tuple (major, minor, micro, level, serial).
2319
2320Dictionaries have an odd new method, setdefault(key, default).
2321dict.setdefault(key, default) returns dict[key] if it exists; if not,
2322it sets dict[key] to default and returns that value. Thus:
2323
2324 dict.setdefault(key, []).append(item)
2325
2326does the same work as this common idiom:
2327
2328 if not dict.has_key(key):
2329 dict[key] = []
2330 dict[key].append(item)
2331
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002332There are two new variants of SyntaxError that are raised for
2333indentation-related errors: IndentationError and TabError.
2334
2335Changed \x to consume exactly two hex digits; see PEP 223. Added \U
2336escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002337
2338The limits on the size of expressions and file in Python source code
2339have been raised from 2**16 to 2**32. Previous versions of Python
2340were limited because the maximum argument size the Python VM accepted
2341was 2**16. This limited the size of object constructor expressions,
2342e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
2343limit was raised thanks to a patch by Charles Waldman that effectively
2344fixes the problem. It is now much more likely that you will be
2345limited by available memory than by an arbitrary limit in Python.
2346
2347The interpreter's maximum recursion depth can be modified by Python
2348programs using sys.getrecursionlimit and sys.setrecursionlimit. This
2349limit is the maximum number of recursive calls that can be made by
2350Python code. The limit exists to prevent infinite recursion from
2351overflowing the C stack and causing a core dump. The default value is
23521000. The maximum safe value for a particular platform can be found
2353by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002354
2355New Modules and Packages
2356------------------------
2357
2358atexit - for registering functions to be called when Python exits.
2359
2360imputil - Greg Stein's alternative API for writing custom import
2361hooks.
2362
2363pyexpat - an interface to the Expat XML parser, contributed by Paul
2364Prescod.
2365
2366xml - a new package with XML support code organized (so far) in three
2367subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
2368would fill a volume. There's a special feature whereby a
2369user-installed package named _xmlplus overrides the standard
2370xmlpackage; this is intended to give the XML SIG a hook to distribute
2371backwards-compatible updates to the standard xml package.
2372
2373webbrowser - a platform-independent API to launch a web browser.
2374
2375
Guido van Rossume905e952000-09-05 12:42:46 +00002376Changed Modules
2377---------------
2378
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002379array -- new methods for array objects: count, extend, index, pop, and
2380remove
2381
2382binascii -- new functions b2a_hex and a2b_hex that convert between
2383binary data and its hex representation
2384
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002385calendar -- Many new functions that support features including control
2386over which day of the week is the first day, returning strings instead
2387of printing them. Also new symbolic constants for days of week,
2388e.g. MONDAY, ..., SUNDAY.
2389
2390cgi -- FieldStorage objects have a getvalue method that works like a
2391dictionary's get method and returns the value attribute of the object.
2392
2393ConfigParser -- The parser object has new methods has_option,
2394remove_section, remove_option, set, and write. They allow the module
2395to be used for writing config files as well as reading them.
2396
2397ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002398optionally support the RFC 959 REST command.
2399
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002400gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002401
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002402httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2403the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002404
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002405locale -- implement getdefaultlocale for Win32 and Macintosh
2406
2407marshal -- no longer dumps core when marshaling deeply nested or
2408recursive data structures
2409
2410os -- new functions isatty, seteuid, setegid, setreuid, setregid
2411
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002412os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2413support under Unix.
2414
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002415os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002416
2417os.path -- fix semantics of os.path.commonprefix
2418
2419smtplib -- support for sending very long messages
2420
2421socket -- new function getfqdn()
2422
2423readline -- new functions to read, write and truncate history files.
2424The readline section of the library reference manual contains an
2425example.
2426
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002427select -- add interface to poll system call
2428
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002429shutil -- new copyfileobj function
2430
2431SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2432HTTP server.
2433
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002434Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002435
2436urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002437e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002438
2439whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002440
2441
2442Obsolete Modules
2443----------------
2444
2445None. However note that 1.6 made a whole slew of modules obsolete:
2446stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2447poly, zmod, strop, util, whatsound.
2448
2449
2450Changed, New, Obsolete Tools
2451----------------------------
2452
Tim Peters8b092332000-09-05 20:15:25 +00002453None.
Guido van Rossume905e952000-09-05 12:42:46 +00002454
2455
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002456C-level Changes
2457---------------
2458
2459Several cleanup jobs were carried out throughout the source code.
2460
2461All C code was converted to ANSI C; we got rid of all uses of the
2462Py_PROTO() macro, which makes the header files a lot more readable.
2463
2464Most of the portability hacks were moved to a new header file,
2465pyport.h; several other new header files were added and some old
2466header files were removed, in an attempt to create a more rational set
2467of header files. (Few of these ever need to be included explicitly;
2468they are all included by Python.h.)
2469
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002470Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002471and Win64, especially for the new Intel Itanium processor. Mick also
2472added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002473
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002474The C APIs to return an object's size have been update to consistently
2475use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2476previous versions, the abstract interfaces used PyXXX_Length and the
2477concrete interfaces used PyXXX_Size. The old names,
2478e.g. PyObject_Length, are still available for backwards compatibility
2479at the API level, but are deprecated.
2480
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002481The PyOS_CheckStack function has been implemented on Windows by
2482Fredrik Lundh. It prevents Python from failing with a stack overflow
2483on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002484
2485The GC changes resulted in creation of two new slots on object,
2486tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002487the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002488
2489The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002490C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002491
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002492PyErr_Format has been updated to automatically calculate the size of
2493the buffer needed to hold the formatted result string. This change
2494prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002495
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002496New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002497
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002498PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2499that are the same as their non-Ex counterparts except they take an
2500extra flag argument that tells them to close the file when done.
2501
2502XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002503
Tim Peters8b092332000-09-05 20:15:25 +00002504
2505Windows Changes
2506---------------
2507
2508New popen2/popen3/peopen4 in os module (see Changed Modules above).
2509
2510os.popen is much more usable on Windows 95 and 98. See Microsoft
2511Knowledge Base article Q150956. The Win9x workaround described there
2512is implemented by the new w9xpopen.exe helper in the root of your
2513Python installation. Note that Python uses this internally; it is not
2514a standalone program.
2515
2516Administrator privileges are no longer required to install Python
2517on Windows NT or Windows 2000. If you have administrator privileges,
2518Python's registry info will be written under HKEY_LOCAL_MACHINE.
2519Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002520under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002521uses of Python, but will prevent some advanced uses from working
2522(for example, running a Python script as an NT service, or possibly
2523from CGI).
2524
2525[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2526installer; instead, it installs the needed Tcl/Tk files directly in the
2527Python directory. If you already have a Tcl/Tk installation, this
2528wastes some disk space (about 4 Megs) but avoids problems with
2529conflicting Tcl/Tk installations, and makes it much easier for Python
2530to ensure that Tcl/Tk can find all its files.
2531
2532[This was new in 1.6] The Windows installer now installs by default in
2533\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2534
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002535
2536Updates to the changes between 1.5.2 and 1.6
2537--------------------------------------------
2538
2539The 1.6 NEWS file can't be changed after the release is done, so here
2540is some late-breaking news:
2541
2542New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2543and changes to getlocale() and setlocale().
2544
2545The new module is now enabled per default.
2546
2547It is not true that the encodings codecs cannot be used for normal
2548strings: the string.encode() (which is also present on 8-bit strings
2549!) allows using them for 8-bit strings too, e.g. to convert files from
2550cp1252 (Windows) to latin-1 or vice-versa.
2551
2552Japanese codecs are available from Tamito KAJIYAMA:
2553http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2554
2555
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002556======================================================================