blob: 9ead40c81aa784be44681072631812a8229bc0b1 [file] [log] [blame]
Tim Petersabf925f2001-09-28 21:53:42 +00001What's New in Python 2.2b1?
2Release date: 28-Sep-2100
3===========================
4
5Type/class unification and new-style classes
6
7Core
8
Martin v. Löwis16dc7f42001-09-30 20:32:11 +00009- binascii has now two quopri support functions, a2b_qp and b2a_qp.
10
Martin v. Löwis0daad592001-09-30 21:09:59 +000011- readline now supports setting the startup_hook and the pre_event_hook.
12
Tim Petersabf925f2001-09-28 21:53:42 +000013Library
14
Tim Peters7402f792001-10-02 03:53:41 +000015- doctest now excludes functions and classes not defined by the module
16 being tested, thanks to Tim Hochberg.
17
Martin v. Löwis16dc7f42001-09-30 20:32:11 +000018- quopri's encode and decode methods take an optional header parameter,
19 which indicates whether output is intended for the header 'Q' encoding.
20
Guido van Rossumed554f62001-10-02 23:15:37 +000021Tools/Demos
22
23- Demo/dns was removed. It no longer serves any purpose; a package
24 derived from it is now maintained by Anthony Baxter, see
25 http://PyDNS.SourceForge.net.
Tim Petersabf925f2001-09-28 21:53:42 +000026
27Build
28
29C API
30
Tim Petersd38b1c72001-09-30 05:09:37 +000031- PyLong_AsLongLong() now accepts int (as well as long) arguments.
32 Consequently, PyArg_ParseTuple's 'L' code also accepts int (as well
33 as long) arguments.
34
Tim Petersabf925f2001-09-28 21:53:42 +000035New platforms
36
37Tests
38
39Windows
40
Tim Peters1ce3cf72001-10-01 17:58:40 +000041- The signal module now supports SIGBREAK on Windows, thanks to Steven
42 Scott. Note that SIGBREAK is unique to Windows. The default SIGBREAK
43 action remains to call Win32 ExitProcess(). This can be changed via
44 signal.signal(). For example:
45
46 # Make Ctrl+Break raise KeyboardInterrupt, like Python's default Ctrl+C
47 # (SIGINT) behavior.
48 import signal
49 signal.signal(signal.SIGBREAK,
50 signal.default_int_handler)
51
52 try:
53 while 1:
54 pass
55 except KeyboardInterrupt:
56 # We get here on Ctrl+C or Ctrl+Break now; if we had not changed
57 # SIGBREAK, only on Ctrl+C (and Ctrl+Break would terminate the
58 # program without the possibility for any Python-level cleanup).
59 print "Clean exit"
60
Tim Petersabf925f2001-09-28 21:53:42 +000061
Tim Petersb07352e2001-09-08 01:25:47 +000062What's New in Python 2.2a4?
Barry Warsaw86fbaf82001-09-28 15:26:12 +000063Release date: 28-Sep-2001
Tim Petersb07352e2001-09-08 01:25:47 +000064===========================
65
Guido van Rossum808eea72001-09-25 04:15:41 +000066Type/class unification and new-style classes
67
68- pydoc and inspect are now aware of new-style classes;
69 e.g. help(list) at the interactive prompt now shows proper
70 documentation for all operations on list objects.
71
72- Applications using Jim Fulton's ExtensionClass module can now safely
73 be used with Python 2.2. In particular, Zope 2.4.1 now works with
74 Python 2.2 (as well as with Python 2.1.1). The Demo/metaclass
75 examples also work again. It is hoped that Gtk and Boost also work
76 with 2.2a4 and beyond. (If you can confirm this, please write
77 webmaster@python.org; if there are still problems, please open a bug
78 report on SourceForge.)
Tim Petersb07352e2001-09-08 01:25:47 +000079
Tim Peters66c1a522001-09-24 21:17:50 +000080- property() now takes 4 keyword arguments: fget, fset, fdel and doc.
81 These map to readonly attributes 'fget', 'fset', 'fdel', and '__doc__'
82 in the constructed property object. fget, fset and fdel weren't
83 discoverable from Python in 2.2a3. __doc__ is new, and allows to
84 associate a docstring with a property.
85
Guido van Rossum808eea72001-09-25 04:15:41 +000086- Comparison overloading is now more completely implemented. For
87 example, a str subclass instance can properly be compared to a str
88 instance, and it can properly overload comparison. Ditto for most
89 other built-in object types.
90
91- The repr() of new-style classes has changed; instead of <type
92 'M.Foo'> a new-style class is now rendered as <class 'M.Foo'>,
93 *except* for built-in types, which are still rendered as <type
94 'Foo'> (to avoid upsetting existing code that might parse or
95 otherwise rely on repr() of certain type objects).
96
97- The repr() of new-style objects is now always <Foo object at XXX>;
98 previously, it was sometimes <Foo instance at XXX>.
99
100- For new-style classes, what was previously called __getattr__ is now
101 called __getattribute__. This method, if defined, is called for
102 *every* attribute access. A new __getattr__ hook mor similar to the
103 one in classic classes is defined which is called only if regular
104 attribute access raises AttributeError; to catch *all* attribute
105 access, you can use __getattribute__ (for new-style classes). If
106 both are defined, __getattribute__ is called first, and if it raises
107 AttributeError, __getattr__ is called.
108
109- The __class__ attribute of new-style objects can be assigned to.
110 The new class must have the same C-level object layout as the old
111 class.
112
113- The builtin file type can be subclassed now. In the usual pattern,
114 "file" is the name of the builtin type, and file() is a new builtin
115 constructor, with the same signature as the builtin open() function.
116 file() is now the preferred way to open a file.
117
118- Previously, __new__ would only see sequential arguments passed to
119 the type in a constructor call; __init__ would see both sequential
120 and keyword arguments. This made no sense whatsoever any more, so
121 now both __new__ and __init__ see all arguments.
122
123- Previously, hash() applied to an instance of a subclass of str or
124 unicode always returned 0. This has been repaired.
125
126- Previously, an operation on an instance of a subclass of an
127 immutable type (int, long, float, complex, tuple, str, unicode),
128 where the subtype didn't override the operation (and so the
129 operation was handled by the builtin type), could return that
130 instance instead a value of the base type. For example, if s was of
131 a str sublass type, s[:] returned s as-is. Now it returns a str
132 with the same value as s.
133
Barry Warsaw86fbaf82001-09-28 15:26:12 +0000134- Provisional support for pickling new-style objects has been added.
135
Guido van Rossum808eea72001-09-25 04:15:41 +0000136Core
137
Tim Peters2c9aa5e2001-09-23 04:06:05 +0000138- file.writelines() now accepts any iterable object producing strings.
139
Marc-André Lemburgaefd7662001-09-20 12:59:37 +0000140- PyUnicode_FromEncodedObject() now works very much like
141 PyObject_Str(obj) in that it tries to use __str__/tp_str
142 on the object if the object is not a string or buffer. This
143 makes unicode() behave like str() when applied to non-string/buffer
144 objects.
145
Martin v. Löwis2777c022001-09-19 13:47:32 +0000146- PyFile_WriteObject now passes Unicode object to the file's write
147 method. As a result, all file-like object which may be the target
148 of a print statement must support Unicode objects, i.e. they must
149 at least convert them into ASCII strings.
150
Guido van Rossum624c8af2001-09-18 15:21:04 +0000151- Thread scheduling on Solaris should be improved; it is no longer
152 necessary to insert a small sleep at the start of a thread in order
153 to let other runnable threads be scheduled.
154
Tim Petersb07352e2001-09-08 01:25:47 +0000155Library
156
Marc-André Lemburgbf990172001-09-27 14:17:33 +0000157- StringIO.StringIO instances and cStringIO.StringIO instances support
158 read character buffer compatible objects for their .write() methods.
159 These objects are converted to strings and then handled as such
160 by the instances.
161
Barry Warsaw2f600732001-09-24 04:28:10 +0000162- The "email" package has been added. This is basically a port of the
163 mimelib package <http://sf.net/projects/mimelib> with API changes
164 and some implementations updated to use iterators and generators.
165
Tim Peters8a9c2842001-09-22 21:30:22 +0000166- difflib.ndiff() and difflib.Differ.compare() are generators now. This
167 restores the ability of Tools/scripts/ndiff.py to start producing output
168 before the entire comparison is complete.
169
Barry Warsaw58b072d2001-09-22 04:44:21 +0000170- StringIO.StringIO instances and cStringIO.StringIO instances support
171 iteration just like file objects (i.e. their .readline() method is
172 called for each iteration until it returns an empty string).
173
Marc-André Lemburg494f2ae2001-09-19 11:33:31 +0000174- The codecs module has grown four new helper APIs to access
175 builtin codecs: getencoder(), getdecoder(), getreader(),
176 getwriter().
177
Guido van Rossum624c8af2001-09-18 15:21:04 +0000178- SimpleXMLRPCServer: a new module (based upon SimpleHTMLServer)
179 simplifies writing XML RPC servers.
180
Barry Warsaw647d5e82001-09-28 17:01:02 +0000181- os.path.realpath(): a new function that returns the absolute pathname
Guido van Rossum624c8af2001-09-18 15:21:04 +0000182 after interpretation of symbolic links. On non-Unix systems, this
183 is an alias for os.path.abspath().
184
Tim Peters16a77ad2001-09-08 04:00:12 +0000185- operator.indexOf() (PySequence_Index() in the C API) now works with any
186 iterable object.
187
Guido van Rossum624c8af2001-09-18 15:21:04 +0000188- smtplib now supports various authentication and security features of
189 the SMTP protocol through the new login() and starttls() methods.
Guido van Rossumd8185ca2001-09-14 16:35:16 +0000190
Guido van Rossum624c8af2001-09-18 15:21:04 +0000191- hmac: a new module implementing keyed hashing for message
192 authentication.
193
194- mimetypes now recognizes more extensions and file types. At the
195 same time, some mappings not sanctioned by IANA were removed.
Guido van Rossumd8185ca2001-09-14 16:35:16 +0000196
Guido van Rossum624c8af2001-09-18 15:21:04 +0000197- The "compiler" package has been brought up to date to the state of
Guido van Rossumc9ed5dc2001-09-20 05:30:24 +0000198 Python 2.2 bytecode generation. It has also been promoted from a
199 Tool to a standard library package. (Tools/compiler still exists as
200 a sample driver.)
201
Guido van Rossumc9ed5dc2001-09-20 05:30:24 +0000202Tools
Guido van Rossum624c8af2001-09-18 15:21:04 +0000203
Tim Petersb07352e2001-09-08 01:25:47 +0000204Build
205
Guido van Rossum624c8af2001-09-18 15:21:04 +0000206- Large file support (LFS) is now automatic when the platform supports
207 it; no more manual configuration tweaks are needed. On Linux, at
208 least, it's possible to have a system whose C library supports large
209 files but whose kernel doesn't; in this case, large file support is
210 still enabled but doesn't do you any good unless you upgrade your
211 kernel or share your Python executable with another system whose
212 kernel has large file support.
213
214- The configure script now supplies plausible defaults in a
215 cross-compilation environment. This doesn't mean that the supplied
216 values are always correct, or that cross-compilation now works
217 flawlessly -- but it's a first step (and it shuts up most of
218 autoconf's warnings about AC_TRY_RUN).
219
220- The Unix build is now a bit less chatty, courtesy of the parser
221 generator. The build is completely silent (except for errors) when
222 using "make -s", thanks to a -q option to setup.py.
223
Tim Petersb07352e2001-09-08 01:25:47 +0000224C API
225
Guido van Rossum624c8af2001-09-18 15:21:04 +0000226- The "structmember" API now supports some new flag bits to deny read
227 and/or write access to attributes in restricted execution mode.
228
Tim Petersb07352e2001-09-08 01:25:47 +0000229New platforms
230
Guido van Rossum624c8af2001-09-18 15:21:04 +0000231- Compaq's iPAQ handheld, running the "familiar" Linux distribution
232 (http://familiar.handhelds.org).
233
Tim Petersb07352e2001-09-08 01:25:47 +0000234Tests
235
Tim Peters8a9c2842001-09-22 21:30:22 +0000236- The "classic" standard tests, which work by comparing stdout to
237 an expected-output file under Lib/test/output/, no longer stop at
238 the first mismatch. Instead the test is run to completion, and a
239 variant of ndiff-style comparison is used to report all differences.
240 This is much easier to understand than the previous style of reporting.
241
242- The unittest-based standard tests now use regrtest's test_main()
243 convention, instead of running as a side-effect of merely being
244 imported. This allows these tests to be run in more natural and
245 flexible ways as unittests, outside the regrtest framework.
246
247- regrtest.py is much better integrated with unittest and doctest now,
248 especially in regard to reporting errors.
249
Tim Petersb07352e2001-09-08 01:25:47 +0000250Windows
251
Guido van Rossum624c8af2001-09-18 15:21:04 +0000252- Large file support now also works for files > 4GB, on filesystems
Tim Peters8a9c2842001-09-22 21:30:22 +0000253 that support it (NTFS under Windows 2000). See "What's New in
254 Python 2.2a3" for more detail.
Guido van Rossum624c8af2001-09-18 15:21:04 +0000255
Tim Petersb07352e2001-09-08 01:25:47 +0000256
Tim Petersedc99312001-08-22 21:36:50 +0000257What's New in Python 2.2a3?
Barry Warsaw86fbaf82001-09-28 15:26:12 +0000258Release Date: 07-Sep-2001
Tim Petersedc99312001-08-22 21:36:50 +0000259===========================
260
261Core
262
Tim Peters9fffa3e2001-09-04 05:14:19 +0000263- Conversion of long to float now raises OverflowError if the long is too
264 big to represent as a C double.
265
Tim Peters32f453e2001-09-03 08:35:41 +0000266- The 3-argument builtin pow() no longer allows a third non-None argument
267 if either of the first two arguments is a float, or if both are of
268 integer types and the second argument is negative (in which latter case
269 the arguments are converted to float, so this is really the same
270 restriction).
271
Tim Peters5d2b77c2001-09-03 05:47:38 +0000272- The builtin dir() now returns more information, and sometimes much
273 more, generally naming all attributes of an object, and all attributes
274 reachable from the object via its class, and from its class's base
275 classes, and so on from them too. Example: in 2.2a2, dir([]) returned
276 an empty list. In 2.2a3,
277
278 >>> dir([])
279 ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__',
280 '__eq__', '__ge__', '__getattr__', '__getitem__', '__getslice__',
281 '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__le__',
282 '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__repr__',
283 '__rmul__', '__setattr__', '__setitem__', '__setslice__', '__str__',
284 'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove',
285 'reverse', 'sort']
286
287 dir(module) continues to return only the module's attributes, though.
288
Tim Petersbdee63f2001-09-02 03:40:59 +0000289- Overflowing operations on plain ints now return a long int rather
Guido van Rossumae457142001-08-31 18:31:35 +0000290 than raising OverflowError. This is a partial implementation of PEP
291 237. You can use -Wdefault::OverflowWarning to enable a warning for
292 this situation, and -Werror::OverflowWarning to revert to the old
293 OverflowError exception.
294
Guido van Rossum61c345f2001-09-04 03:26:15 +0000295- A new command line option, -Q<arg>, is added to control run-time
Guido van Rossumae457142001-08-31 18:31:35 +0000296 warnings for the use of classic division. (See PEP 238.) Possible
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000297 values are -Qold, -Qwarn, -Qwarnall, and -Qnew. The default is
298 -Qold, meaning the / operator has its classic meaning and no
299 warnings are issued. Using -Qwarn issues a run-time warning about
300 all uses of classic division for int and long arguments; -Qwarnall
301 also warns about classic division for float and complex arguments
302 (for use with fixdiv.py). Using -Qnew is questionable; it turns on
303 new division by default, but only in the __main__ module. You can
304 usefully combine -Qwarn or -Qwarnall and -Qnew: this gives the
305 __main__ module new division, and warns about classic division
306 everywhere else.
Guido van Rossumae457142001-08-31 18:31:35 +0000307
Tim Petersbdee63f2001-09-02 03:40:59 +0000308- Many built-in types can now be subclassed. This applies to int,
Guido van Rossumae457142001-08-31 18:31:35 +0000309 long, float, str, unicode, and tuple. (The types complex, list and
310 dictionary can also be subclassed; this was introduced earlier.)
311 Note that restrictions apply when subclassing immutable built-in
312 types: you can only affect the value of the instance by overloading
313 __new__. You can add mutable attributes, and the subclass instances
314 will have a __dict__ attribute, but you cannot change the "value"
315 (as implemented by the base class) of an immutable subclass instance
316 once it is created.
317
Guido van Rossumaaf80c82001-09-02 13:44:35 +0000318- The dictionary constructor now takes an optional argument, a
319 mapping-like object, and initializes the dictionary from its
320 (key, value) pairs.
321
Tim Petersbdee63f2001-09-02 03:40:59 +0000322- A new built-in type, super, has been added. This facilitates making
Guido van Rossumae457142001-08-31 18:31:35 +0000323 "cooperative super calls" in a multiple inheritance setting. For an
324 explanation, see http://www.python.org/2.2/descrintro.html#cooperation
325
Guido van Rossum8d7234d2001-09-06 22:02:58 +0000326- A new built-in type, property, has been added. This enables the
327 creation of "properties". These are attributes implemented by
328 getter and setter functions (or only one of these for read-only or
329 write-only attributes), without the need to override __getattr__.
330 See http://www.python.org/2.2/descrintro.html#property
Guido van Rossumae457142001-08-31 18:31:35 +0000331
Tim Petersbdee63f2001-09-02 03:40:59 +0000332- The syntax of floating-point and imaginary literals has been
Tim Petersd507dab2001-08-30 20:51:59 +0000333 liberalized, to allow leading zeroes. Examples of literals now
334 legal that were SyntaxErrors before:
335
336 00.0 0e3 0100j 07.5 00000000000000000008.
337
Tim Petersbdee63f2001-09-02 03:40:59 +0000338- An old tokenizer bug allowed floating point literals with an incomplete
Tim Petersc6d95812001-08-28 20:56:27 +0000339 exponent, such as 1e and 3.1e-. Such literals now raise SyntaxError.
340
Tim Petersedc99312001-08-22 21:36:50 +0000341Library
342
Martin v. Löwiscb227c92001-09-06 08:54:16 +0000343- telnetlib includes symbolic names for the options, and support for
344 setting an option negotiation callback.
345
Tim Petersa40c7932001-09-05 22:36:56 +0000346- The new C standard no longer requires that math libraries set errno to
347 ERANGE on overflow. For platform libraries that exploit this new
348 freedom, Python's overflow-checking was wholly broken. A new overflow-
349 checking scheme attempts to repair that, but may not be reliable on all
350 platforms (C doesn't seem to provide anything both useful and portable
351 in this area anymore).
352
Martin v. Löwis44f86962001-09-05 13:44:54 +0000353- Asynchronous timeout actions are available through the new class
354 threading.Timer.
355
Tim Peters78526162001-09-05 00:53:45 +0000356- math.log and math.log10 now return sensible results for even huge
357 long arguments. For example, math.log10(10 ** 10000) ~= 10000.0.
358
Tim Petersbdee63f2001-09-02 03:40:59 +0000359- A new function, imp.lock_held(), returns 1 when the import lock is
Tim Peters69232342001-08-30 05:16:13 +0000360 currently held. See the docs for the imp module.
361
Tim Petersbdee63f2001-09-02 03:40:59 +0000362- pickle, cPickle and marshal on 32-bit platforms can now correctly read
Tim Peters82112372001-08-29 02:28:42 +0000363 dumps containing ints written on platforms where Python ints are 8 bytes.
364 When read on a box where Python ints are 4 bytes, such values are
365 converted to Python longs.
366
Tim Petersbdee63f2001-09-02 03:40:59 +0000367- In restricted execution mode (using the rexec module), unmarshalling
Guido van Rossumae457142001-08-31 18:31:35 +0000368 code objects is no longer allowed. This plugs a security hole.
369
Steve Purcell6091cd62001-09-06 16:05:17 +0000370- unittest.TestResult instances no longer store references to tracebacks
371 generated by test failures. This prevents unexpected dangling references
372 to objects that should be garbage collected between tests.
373
Tim Petersedc99312001-08-22 21:36:50 +0000374Tools
375
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000376- Tools/scripts/fixdiv.py has been added which can be used to fix
377 division operators as per PEP 238.
378
Tim Petersedc99312001-08-22 21:36:50 +0000379Build
380
Barry Warsawd6c8ca62001-09-07 18:13:44 +0000381- If you are an adventurous person using Mac OS X you may want to look at
382 Mac/OSX. There is a Makefile there that will build Python as a real Mac
383 application, which can be used for experimenting with Carbon or Cocoa.
384 Discussion of this on pythonmac-sig, please.
385
Tim Peters7eea37e2001-09-04 22:08:56 +0000386C API
387
388- New function PyObject_Dir(obj), like Python __builtin__.dir(obj).
Tim Peters69232342001-08-30 05:16:13 +0000389
Tim Peters9fffa3e2001-09-04 05:14:19 +0000390- Note that PyLong_AsDouble can fail! This has always been true, but no
391 callers checked for it. It's more likely to fail now, because overflow
392 errors are properly detected now. The proper way to check:
393
394 double x = PyLong_AsDouble(some_long_object);
395 if (x == -1.0 && PyErr_Occurred()) {
396 /* The conversion failed. */
397 }
398
Tim Petersbdee63f2001-09-02 03:40:59 +0000399- The GC API has been changed. Extensions that use the old API will still
Neil Schemenauer4042c692001-08-30 15:38:01 +0000400 compile but will not participate in GC. To upgrade an extension
401 module:
402
403 - rename Py_TPFLAGS_GC to PyTPFLAGS_HAVE_GC
Tim Petersd507dab2001-08-30 20:51:59 +0000404
Neil Schemenauer4042c692001-08-30 15:38:01 +0000405 - use PyObject_GC_New or PyObject_GC_NewVar to allocate objects and
406 PyObject_GC_Del to deallocate them
Tim Petersd507dab2001-08-30 20:51:59 +0000407
Neil Schemenauer4042c692001-08-30 15:38:01 +0000408 - rename PyObject_GC_Init to PyObject_GC_Track and PyObject_GC_Fini
409 to PyObject_GC_UnTrack
Tim Petersd507dab2001-08-30 20:51:59 +0000410
Neil Schemenauer4042c692001-08-30 15:38:01 +0000411 - remove PyGC_HEAD_SIZE from object size calculations
412
413 - remove calls to PyObject_AS_GC and PyObject_FROM_GC
414
Tim Petersbdee63f2001-09-02 03:40:59 +0000415- Two new functions: PyString_FromFormat() and PyString_FromFormatV().
Guido van Rossumae457142001-08-31 18:31:35 +0000416 These can be used safely to construct string objects from a
417 sprintf-style format string (similar to the format string supported
418 by PyErr_Format()).
Tim Peters69232342001-08-30 05:16:13 +0000419
Tim Petersedc99312001-08-22 21:36:50 +0000420New platforms
421
Tim Petersb7da0902001-09-02 23:01:43 +0000422- Stephen Hansen contributed patches sufficient to get a clean compile
423 under Borland C (Windows), but he reports problems running it and ran
424 out of time to complete the port. Volunteers? Expect a MemoryError
425 when importing the types module; this is probably shallow, and
426 causing later failures too.
Tim Petersbdee63f2001-09-02 03:40:59 +0000427
Tim Petersedc99312001-08-22 21:36:50 +0000428Tests
429
430Windows
431
Tim Peters6e13a562001-09-06 00:32:15 +0000432- Large file support is now enabled on Win32 platforms as well as on
433 Win64. This means that, for example, you can use f.tell() and f.seek()
434 to manipulate files larger than 2 gigabytes (provided you have enough
435 disk space, and are using a Windows filesystem that supports large
Tim Peters9a9471c2001-09-11 23:18:51 +0000436 partitions). Windows filesystem limits: FAT has a 2GB (gigabyte)
437 filesize limit, and large file support makes no difference there.
438 FAT32's limit is 4GB, and files >= 2GB are easier to use from Python now.
439 NTFS has no practical limit on file size, and files of any size can be
440 used from Python now.
Tim Peters6e13a562001-09-06 00:32:15 +0000441
Tim Petersbdee63f2001-09-02 03:40:59 +0000442- The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
Tim Peters402d5982001-08-27 06:37:48 +0000443 points to command.com (patch from Brian Quinlan).
444
Tim Petersedc99312001-08-22 21:36:50 +0000445
Tim Peters20f51a72001-07-21 02:31:40 +0000446What's New in Python 2.2a2?
Barry Warsaw86fbaf82001-09-28 15:26:12 +0000447Release Date: 22-Aug-2001
Tim Peters20f51a72001-07-21 02:31:40 +0000448===========================
449
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000450Build
451
Barry Warsaw18b2ecf2001-08-22 20:26:56 +0000452- Tim Peters developed a brand new Windows installer using Wise 8.1,
453 generously donated to us by Wise Solutions.
454
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000455- configure supports a new option --enable-unicode, with the values
456 ucs2 and ucs4 (new in 2.2a1). With --disable-unicode, the Unicode
457 type and supporting code is completely removed from the interpreter.
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000458
Jack Jansen32ce0cd2001-08-21 19:28:20 +0000459- A new configure option --enable-framework builds a Mac OS X framework,
460 which "make frameworkinstall" will install. This provides a starting
461 point for more mac-like functionality, join pythonmac-sig@python.org
462 if you are interested in helping.
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000463
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000464- The NeXT platform is no longer supported.
465
466- The `new' module is now statically linked.
467
Tim Peters0afb6092001-08-15 06:06:44 +0000468Tools
469
470- The new Tools/scripts/cleanfuture.py can be used to automatically
Andrew M. Kuchlingb0532092001-08-15 15:54:56 +0000471 edit out obsolete future statements from Python source code. See
Tim Peters0afb6092001-08-15 06:06:44 +0000472 the module docstring for details.
473
Tim Peters20f51a72001-07-21 02:31:40 +0000474Tests
475
Tim Peters5e824c32001-08-12 22:25:01 +0000476- regrtest.py now knows which tests are expected to be skipped on some
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000477 platforms, allowing to give clearer test result output. regrtest
478 also has optional --use/-u switch to run normally disabled tests
479 which require network access or consume significant disk resources.
Tim Peters5e824c32001-08-12 22:25:01 +0000480
Tim Peters20f51a72001-07-21 02:31:40 +0000481- Several new tests in the standard test suite, with special thanks to
482 Nick Mathewson.
483
484Core
485
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000486- The floor division operator // has been added as outlined in PEP
487 238. The / operator still provides classic division (and will until
488 Python 3.0) unless "from __future__ import division" is included, in
489 which case the / operator will provide true division. The operator
490 module provides truediv() and floordiv() functions. Augmented
491 assignment variants are included, as are the equivalent overloadable
492 methods and C API methods. See the PEP for a full discussion:
493 <http://python.sf.net/peps/pep-0238.html>
494
Tim Peters6cd6a822001-08-17 22:11:27 +0000495- Future statements are now effective in simulated interactive shells
496 (like IDLE). This should "just work" by magic, but read Michael
497 Hudson's "Future statements in simulated shells" PEP 264 for full
498 details: <http://python.sf.net/peps/pep-0264.html>.
499
Guido van Rossumf86ddd22001-08-17 21:21:04 +0000500- The type/class unification (PEP 252-253) was integrated into the
501 trunk and is not so tentative any more (the exact specification of
502 some features is still tentative). A lot of work has done on fixing
503 bugs and adding robustness and features (performance still has to
504 come a long way).
505
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000506- Warnings about a mismatch in the Python API during extension import
507 now use the Python warning framework (which makes it possible to
508 write filters for these warnings).
509
Barry Warsaw9b3be7f2001-08-14 18:35:02 +0000510- A function's __dict__ (aka func_dict) will now always be a
511 dictionary. It used to be possible to delete it or set it to None,
512 but now both actions raise TypeErrors. It is still legal to set it
513 to a dictionary object. Getting func.__dict__ before any attributes
514 have been assigned now returns an empty dictionary instead of None.
515
Guido van Rossum32aa5d22001-09-05 18:43:35 +0000516- A new command line option, -E, was added which disables the use of
517 all environment variables, or at least those that are specifically
518 significant to Python. Usually those have a name starting with
519 "PYTHON". This was used to fix a problem where the tests fail if
520 the user happens to have PYTHONHOME or PYTHONPATH pointing to an
521 older distribution.
522
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000523Library
524
Tim Peters5e824c32001-08-12 22:25:01 +0000525- New class Differ and new functions ndiff() and restore() in difflib.py.
526 These package the algorithms used by the popular Tools/scripts/ndiff.py,
Tim Peters0afb6092001-08-15 06:06:44 +0000527 for programmatic reuse.
Tim Peters5e824c32001-08-12 22:25:01 +0000528
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000529- New function xml.sax.saxutils.quoteattr(): Quote an XML attribute
530 value using the minimal quoting required for the value; more
531 reliable than using xml.sax.saxutils.escape() for attribute values.
532
533- Readline completion support for cmd.Cmd was added.
534
Barry Warsaw6f3410d2001-08-22 04:08:41 +0000535- Calling os.tempnam() or os.tmpnam() generate RuntimeWarnings.
536
537- Added function threading.BoundedSemaphore()
538
539- Added Ka-Ping Yee's cgitb.py module.
540
541- The `new' module now exposes the CO_xxx flags.
542
Marc-André Lemburgd6277912001-07-31 14:42:42 +0000543New platforms
544
545C API
546
Marc-André Lemburg888fac02001-07-31 14:24:31 +0000547- Two new APIs PyOS_snprintf() and PyOS_vsnprintf() were added
548 which provide a cross-platform implementations for the
549 relatively new snprintf()/vsnprintf() C lib APIs. In contrast to
550 the standard sprintf() and vsprintf() C lib APIs, these versions
551 apply bounds checking on the used buffer which enhances protection
552 against buffer overruns.
553
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000554- Unicode APIs now use name mangling to assure that mixing interpreters
Tim Petersc1731372001-08-04 08:12:36 +0000555 and extensions using different Unicode widths is rendered next to
556 impossible. Trying to import an incompatible Unicode-aware extension
Marc-André Lemburg48dbfe92001-07-31 14:37:40 +0000557 will result in an ImportError. Unicode extensions writers must make
558 sure to check the Unicode width compatibility in their extensions by
559 using at least one of the mangled Unicode APIs in the extension.
560
Martin v. Löwis339d0f72001-08-17 18:39:25 +0000561- Two new flags METH_NOARGS and METH_O are available in method definition
562 tables to simplify implementation of methods with no arguments and a
563 single untyped argument. Calling such methods is more efficient than
564 calling corresponding METH_VARARGS methods. METH_OLDARGS is now
565 deprecated.
566
Tim Petersc1731372001-08-04 08:12:36 +0000567Windows
568
569- "import module" now compiles module.pyw if it exists and nothing else
570 relevant is found.
571
Tim Peters20f51a72001-07-21 02:31:40 +0000572
Guido van Rossum55a78992001-07-17 17:22:32 +0000573What's New in Python 2.2a1?
Tim Petersf553f892001-05-01 20:45:31 +0000574===========================
575
576Core
Tim Petersa814db52001-05-14 07:05:58 +0000577
Tim Peters6d6c1a32001-08-02 04:15:00 +0000578- TENTATIVELY, a large amount of code implementing much of what's
579 described in PEP 252 (Making Types Look More Like Classes) and PEP
580 253 (Subtyping Built-in Types) was added. This will be released
581 with Python 2.2a1. Documentation will be provided separately
582 through http://www.python.org/2.2/. The purpose of releasing this
583 with Python 2.2a1 is to test backwards compatibility. It is
584 possible, though not likely, that a decision is made not to release
585 this code as part of 2.2 final, if any serious backwards
586 incompapatibilities are found during alpha testing that cannot be
587 repaired.
588
Guido van Rossum55a78992001-07-17 17:22:32 +0000589- Generators were added; this is a new way to create an iterator (see
Tim Peters11a0d102001-07-17 18:48:00 +0000590 below) using what looks like a simple function containing one or
Guido van Rossum55a78992001-07-17 17:22:32 +0000591 more 'yield' statements. See PEP 255. Since this adds a new
592 keyword to the language, this feature must be enabled by including a
593 future statement: "from __future__ import generators" (see PEP 236).
594 Generators will become a standard feature in a future release
595 (probably 2.3). Without this future statement, 'yield' remains an
596 ordinary identifier, but a warning is issued each time it is used.
597 (These warnings currently don't conform to the warnings framework of
598 PEP 230; we intend to fix this in 2.2a2.)
599
Marc-André Lemburg12e74b32001-05-22 08:58:23 +0000600- The UTF-16 codec was modified to be more RFC compliant. It will now
601 only remove BOM characters at the start of the string and then
602 only if running in native mode (UTF-16-LE and -BE won't remove a
603 leading BMO character).
604
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000605- Strings now have a new method .decode() to complement the already
606 existing .encode() method. These two methods provide direct access
607 to the corresponding decoders and encoders of the registered codecs.
608
609 To enhance the usability of the .encode() method, the special
610 casing of Unicode object return values was dropped (Unicode objects
611 were auto-magically converted to string using the default encoding).
Tim Peterseb28ef22001-06-02 05:27:19 +0000612
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000613 Both methods will now return whatever the codec in charge of the
614 requested encoding returns as object, e.g. Unicode codecs will
615 return Unicode objects when decoding is requested ("äöü".decode("latin-1")
616 will return u"äöü"). This enables codec writer to create codecs
617 for various simple to use conversions.
618
619 New codecs were added to demonstrate these new features (the .encode()
620 and .decode() columns indicate the type of the returned objects):
621
622 Name | .encode() | .decode() | Description
623 ----------------------------------------------------------------------
624 uu | string | string | UU codec (e.g. for email)
625 base64 | string | string | base64 codec
Guido van Rossumc3415802001-06-06 13:30:54 +0000626 quopri | string | string | quoted-printable codec
Marc-André Lemburgfab96cc2001-05-15 18:38:45 +0000627 zlib | string | string | zlib compression
628 hex | string | string | 2-byte hex codec
629 rot-13 | string | Unicode | ROT-13 Unicode charmap codec
630
Mark Hammond2a0af792001-05-14 03:09:36 +0000631- Some operating systems now support the concept of a default Unicode
632 encoding for file system operations. Notably, Windows supports 'mbcs'
633 as the default. The Macintosh will also adopt this concept in the medium
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000634 term, although the default encoding for that platform will be other than
Mark Hammond2a0af792001-05-14 03:09:36 +0000635 'mbcs'.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000636
637 On operating system that support non-ASCII filenames, it is common for
Mark Hammond2a0af792001-05-14 03:09:36 +0000638 functions that return filenames (such as os.listdir()) to return Python
639 string objects pre-encoded using the default file system encoding for
640 the platform. As this encoding is likely to be different from Python's
641 default encoding, converting this name to a Unicode object before passing
642 it back to the Operating System would result in a Unicode error, as Python
Tim Petersa814db52001-05-14 07:05:58 +0000643 would attempt to use its default encoding (generally ASCII) rather than
644 the default encoding for the file system.
Guido van Rossum1bd797a2001-05-14 13:53:38 +0000645
Tim Petersa814db52001-05-14 07:05:58 +0000646 In general, this change simply removes surprises when working with
647 Unicode and the file system, making these operations work as you expect,
648 increasing the transparency of Unicode objects in this context.
Mark Hammond2a0af792001-05-14 03:09:36 +0000649 See [????] for more details, including examples.
Tim Petersf553f892001-05-01 20:45:31 +0000650
Tim Peters61dff2b2001-05-08 15:43:37 +0000651- Float (and complex) literals in source code were evaluated to full
652 precision only when running from a .py file; the same code loaded from a
653 .pyc (or .pyo) file could suffer numeric differences starting at about the
654 12th significant decimal digit. For example, on a machine with IEEE-754
655 floating arithmetic,
656
657 x = 9007199254740992.0
658 print long(x)
659
660 printed 9007199254740992 if run directly from .py, but 9007199254740000
661 if from a compiled (.pyc or .pyo) file. This was due to marshal using
662 str(float) instead of repr(float) when building code objects. marshal
663 now uses repr(float) instead, which should reproduce floats to full
664 machine precision (assuming the platform C float<->string I/O conversion
665 functions are of good quality).
666
667 This may cause floating-point results to change in some cases, and
668 usually for the better, but may also cause numerically unstable
669 algorithms to break.
670
Tim Peters2f228e72001-05-13 00:19:31 +0000671- The implementation of dicts suffers fewer collisions, which has speed
672 benefits. However, the order in which dict entries appear in dict.keys(),
673 dict.values() and dict.items() may differ from previous releases for a
674 given dict. Nothing is defined about this order, so no program should
675 rely on it. Nevertheless, it's easy to write test cases that rely on the
676 order by accident, typically because of printing the str() or repr() of a
677 dict to an "expected results" file. See Lib/test/test_support.py's new
678 sortdict(dict) function for a simple way to display a dict in sorted
679 order.
680
Tim Peters7a3bfc32001-06-12 01:22:22 +0000681- Many other small changes to dicts were made, resulting in faster
682 operation along the most common code paths.
683
Guido van Rossum10315822001-05-01 20:54:30 +0000684- Dictionary objects now support the "in" operator: "x in dict" means
685 the same as dict.has_key(x).
686
Barry Warsaw51acc8d2001-06-26 20:12:50 +0000687- The update() method of dictionaries now accepts generic mapping
688 objects. Specifically the argument object must support the .keys()
689 and __getitem__() methods. This allows you to say, for example,
690 {}.update(UserDict())
691
Guido van Rossum10315822001-05-01 20:54:30 +0000692- Iterators were added; this is a generalized way of providing values
693 to a for loop. See PEP 234. There's a new built-in function iter()
694 to return an iterator. There's a new protocol to get the next value
695 from an iterator using the next() method (in Python) or the
696 tp_iternext slot (in C). There's a new protocol to get iterators
697 using the __iter__() method (in Python) or the tp_iter slot (in C).
698 Iterating (i.e. a for loop) over a dictionary generates its keys.
699 Iterating over a file generates its lines.
700
Tim Petersf553f892001-05-01 20:45:31 +0000701- The following functions were generalized to work nicely with iterator
702 arguments:
Tim Peterse63415e2001-05-08 04:38:29 +0000703 map(), filter(), reduce(), zip()
Tim Peters8572b4f2001-05-06 01:05:02 +0000704 list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
705 max(), min()
Tim Peters1af03e92001-05-26 19:37:54 +0000706 join() method of strings
707 extend() method of lists
Tim Peters75f8e352001-05-05 11:33:43 +0000708 'x in y' and 'x not in y' (PySequence_Contains() in C API)
709 operator.countOf() (PySequence_Count() in C API)
Tim Petersd6d010b2001-06-21 02:49:55 +0000710 right-hand side of assignment statements with multiple targets, such as
711 x, y, z = some_iterable_object_returning_exactly_3_values
Tim Peters75f8e352001-05-05 11:33:43 +0000712
Tim Petersd85e1022001-05-11 21:51:48 +0000713- Accessing module attributes is significantly faster (for example,
714 random.random or os.path or yourPythonModule.yourAttribute).
715
Tim Peterse63415e2001-05-08 04:38:29 +0000716- Comparing dictionary objects via == and != is faster, and now works even
717 if the keys and values don't support comparisons other than ==.
718
Tim Peters95bf9392001-05-10 08:32:44 +0000719- Comparing dictionaries in ways other than == and != is slower: there were
720 insecurities in the dict comparison implementation that could cause Python
721 to crash if the element comparison routines for the dict keys and/or
722 values mutated the dicts. Making the code bulletproof slowed it down.
723
Tim Peterseb28ef22001-06-02 05:27:19 +0000724- Collisions in dicts are resolved via a new approach, which can help
725 dramatically in bad cases. For example, looking up every key in a dict
Tim Peters7a3bfc32001-06-12 01:22:22 +0000726 d with d.keys() == [i << 16 for i in range(20000)] is approximately 500x
Tim Peterseb28ef22001-06-02 05:27:19 +0000727 faster now. Thanks to Christian Tismer for pointing out the cause and
728 the nature of an effective cure (last December! better late than never).
Tim Peters15d49292001-05-27 07:39:22 +0000729
Tim Peters52e155e2001-06-16 05:42:57 +0000730- repr() is much faster for large containers (dict, list, tuple).
731
732
Tim Petersa814db52001-05-14 07:05:58 +0000733Library
734
Fred Drake960fdf92001-07-20 18:38:26 +0000735- The constants ascii_letters, ascii_lowercase. and ascii_uppercase
736 were added to the string module. These a locale-indenpendent
737 constants, unlike letters, lowercase, and uppercase. These are now
738 use in appropriate locations in the standard library.
739
Martin v. Löwisf0473d52001-07-18 16:17:16 +0000740- The flags used in dlopen calls can now be configured using
741 sys.setdlopenflags and queried using sys.getdlopenflags.
742
Guido van Rossumc7e4aca2001-07-12 11:54:37 +0000743- Fredrik Lundh's xmlrpclib is now a standard library module. This
744 provides full client-side XML-RPC support. In addition,
745 Demo/xmlrpc/ contains two server frameworks (one SocketServer-based,
746 one asyncore-based). Thanks to Eric Raymond for the documentation.
747
Guido van Rossum643d3912001-07-05 14:46:25 +0000748- The xrange() object is simplified: it no longer supports slicing,
749 repetition, comparisons, efficient 'in' checking, the tolist()
750 method, or the start, stop and step attributes. See PEP 260.
751
Martin v. Löwisebf94db2001-06-06 06:25:40 +0000752- A new function fnmatch.filter to filter lists of file names was added.
753
Barry Warsawffd674d2001-05-22 16:00:10 +0000754- calendar.py uses month and day names based on the current locale.
755
Guido van Rossum2e0a6542001-05-15 02:14:44 +0000756- strop is now *really* obsolete (this was announced before with 1.6),
757 and issues DeprecationWarning when used (except for the four items
758 that are still imported into string.py).
759
Tim Petersa814db52001-05-14 07:05:58 +0000760- Cookie.py now sorts key+value pairs by key in output strings.
761
762- pprint.isrecursive(object) didn't correctly identify recursive objects.
763 Now it does.
764
Tim Peters95b3f782001-05-14 18:39:41 +0000765- pprint functions now much faster for large containers (tuple, list, dict).
766
Tim Peters7b9542a2001-06-10 23:40:19 +0000767- New 'q' and 'Q' format codes in the struct module, corresponding to C
768 types "long long" and "unsigned long long" (on Windows, __int64). In
769 native mode, these can be used only when the platform C compiler supports
770 these types (when HAVE_LONG_LONG is #define'd by the Python config
771 process), and then they inherit the sizes and alignments of the C types.
Tim Peters7a3bfc32001-06-12 01:22:22 +0000772 In standard mode, 'q' and 'Q' are supported on all platforms, and are
773 8-byte integral types.
Tim Peters7b9542a2001-06-10 23:40:19 +0000774
Guido van Rossum83213cc2001-06-12 16:48:52 +0000775- The site module installs a new built-in function 'help' that invokes
776 pydoc.help. It must be invoked as 'help()'; when invoked as 'help',
777 it displays a message reminding the user to use 'help()' or
778 'help(object)'.
779
Tim Petersa814db52001-05-14 07:05:58 +0000780Tests
781
782- New test_mutants.py runs dict comparisons where the key and value
783 comparison operators mutute the dicts randomly during comparison. This
784 rapidly causes Python to crash under earlier releases (not for the faint
785 of heart: it can also cause Win9x to freeze or reboot!).
786
787- New test_pprint.py verfies that pprint.isrecursive() and
Tim Peters95b3f782001-05-14 18:39:41 +0000788 pprint.isreadable() return sensible results. Also verifies that simple
789 cases produce correct output.
Tim Petersa814db52001-05-14 07:05:58 +0000790
Tim Peters4324aa32001-05-28 22:30:08 +0000791C API
792
793- Removed the unused last_is_sticky argument from the internal
794 _PyTuple_Resize(). If this affects you, you were cheating.
795
796
Guido van Rossum55a78992001-07-17 17:22:32 +0000797======================================================================
798
799
Guido van Rossumffe13be2001-04-16 18:46:45 +0000800What's New in Python 2.1 (final)?
801=================================
802
803We only changed a few things since the last release candidate, all in
804Python library code:
805
806- A bug in the locale module was fixed that affected locales which
807 define no grouping for numeric formatting.
808
809- A few bugs in the weakref module's implementations of weak
810 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
811 and the test suite was updated to check for these bugs.
812
813- An old bug in the os.path.walk() function (introduced in Python
814 2.0!) was fixed: a non-existent file would cause an exception
815 instead of being ignored.
816
817- Fixed a few bugs in the new symtable module found by Neil Norwitz's
818 PyChecker.
819
820
Guido van Rossum5b08f132001-04-16 02:05:23 +0000821What's New in Python 2.1c2?
822===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +0000823
Guido van Rossum5b08f132001-04-16 02:05:23 +0000824A flurry of small changes, and one showstopper fixed in the nick of
825time made it necessary to release another release candidate. The list
826here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +0000827
Guido van Rossum5b08f132001-04-16 02:05:23 +0000828Core
Guido van Rossum4fb60362001-04-13 00:46:14 +0000829
Guido van Rossum5b08f132001-04-16 02:05:23 +0000830- Tim discovered a nasty bug in the dictionary code, caused by
831 PyDict_Next() calling dict_resize(), and the GC code's use of
832 PyDict_Next() violating an assumption in dict_items(). This was
833 fixed with considerable amounts of band-aid, but the net effect is a
834 saner and more robust implementation.
835
836- Made a bunch of symbols static that were accidentally global.
837
838Build and Ports
839
840- The setup.py script didn't check for a new enough version of zlib
841 (1.1.3 is needed). Now it does.
842
843- Changed "make clean" target to also remove shared libraries.
844
845- Added a more general warning about the SGI Irix optimizer to README.
846
847Library
848
849- Fix a bug in urllib.basejoin("http://host", "../file.html") which
850 omitted the slash between host and file.html.
851
852- The mailbox module's _Mailbox class contained a completely broken
853 and undocumented seek() method. Ripped it out.
854
855- Fixed a bunch of typos in various library modules (urllib2, smtpd,
856 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
857
858- Fixed a few last-minute bugs in unittest.
859
860Extensions
861
862- Reverted the patch to the OpenSSL code in socketmodule.c to support
863 RAND_status() and the EGD, and the subsequent patch that tried to
864 fix it for pre-0.9.5 versions; the problem with the patch is that on
865 some systems it issues a warning whenever socket is imported, and
866 that's unacceptable.
867
868Tests
869
870- Fixed the pickle tests to work with "import test.test_pickle".
871
872- Tweaked test_locale.py to actually run the test Windows.
873
874- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
875 not "wb" (which is not a valid mode at all).
876
877- Fix pstats browser crashes. Import readline if it exists to make
878 the user interface nicer.
879
880- Add "import thread" to the top of test modules that import the
881 threading module (test_asynchat and test_threadedtempfile). This
882 prevents test failures caused by a broken threading module resulting
883 from a previously caught failed import.
884
885- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
886 needed on some platforms (e.g. Solaris 8) when the tests are run
887 twice in succession.
888
889- Skip rather than fail test_sunaudiodev if no audio device is found.
890
891
892What's New in Python 2.1c1?
893===========================
894
895This list was significantly updated when 2.1c2 was released; the 2.1c1
896release didn't mention most changes that were actually part of 2.1c1:
897
898Legal
899
900- Copyright was assigned to the Python Software Foundation (PSF) and a
901 PSF license (very similar to the CNRI license) was added.
902
903- The CNRI copyright notice was updated to include 2001.
904
905Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000906
Guido van Rossumc9932722001-04-12 02:31:27 +0000907- After a public outcry, assignment to __debug__ is no longer illegal;
908 instead, a warning is issued. It will become illegal in 2.2.
909
Guido van Rossum5b08f132001-04-16 02:05:23 +0000910- Fixed a core dump with "%#x" % 0, and changed the semantics so that
911 "%#x" now always prepends "0x", even if the value is zero.
912
913- Fixed some nits in the bytecode compiler.
914
915- Fixed core dumps when calling certain kinds of non-functions.
916
917- Fixed various core dumps caused by reference count bugs.
918
919Build and Ports
920
921- Use INSTALL_SCRIPT to install script files.
922
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000923- New port: SCO Unixware 7, by Billy G. Allie.
924
Guido van Rossum5b08f132001-04-16 02:05:23 +0000925- Updated RISCOS port.
926
927- Updated BeOS port and notes.
928
929- Various other porting problems resolved.
930
931Library
932
933- The TERMIOS and SOCKET modules are now truly obsolete and
934 unnecessary. Their symbols are incorporated in the termios and
935 socket modules.
936
937- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
938 better tests for pickling.
939
940- threading: make Condition.wait() robust against KeyboardInterrupt.
941
942- zipfile: add support to zipfile to support opening an archive
943 represented by an open file rather than a file name. Fix bug where
944 the archive was not properly closed. Fixed a bug in this bugfix
945 where flush() was called for a read-only file.
946
947- imputil: added an uninstall() method to the ImportManager.
948
949- Canvas: fixed bugs in lower() and tkraise() methods.
950
951- SocketServer: API change (added overridable close_request() method)
952 so that the TCP server can explicitly close the request.
953
954- pstats: Eric Raymond added a simple interactive statistics browser,
955 invoked when the module is run as a script.
956
957- locale: fixed a problem in format().
958
959- webbrowser: made it work when the BROWSER environment variable has a
960 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
961 KDE 2. Fixed some other nits.
962
963- unittest: changes to allow using a different exception than
964 AssertionError, and added a few more function aliases. Some other
965 small changes.
966
967- urllib, urllib2: fixed redirect problems and a coupleof other nits.
968
969- asynchat: fixed a critical bug in asynchat that slipped through the
970 2.1b2 release. Fixed another rare bug.
971
972- Fix some unqualified except: clauses (always a bad code example).
973
974XML
975
976- pyexpat: new API get_version_string().
977
978- Fixed some minidom bugs.
979
980Extensions
981
982- Fixed a core dump in _weakref. Removed the weakref.mapping()
983 function (it adds nothing to the API).
984
985- Rationalized the use of header files in the readline module, to make
986 it compile (albeit with some warnings) with the very recent readline
987 4.2, without breaking for earlier versions.
988
989- Hopefully fixed a buffering problem in linuxaudiodev.
990
991- Attempted a fix to make the OpenSSL support in the socket module
992 work again with pre-0.9.5 versions of OpenSSL.
993
994Tests
995
996- Added a test case for asynchat and asyncore.
997
998- Removed coupling between tests where one test failing could break
999 another.
1000
1001Tools
1002
1003- Ping added an interactive help browser to pydoc, fixed some nits
1004 in the rest of the pydoc code, and added some features to his
1005 inspect module.
1006
1007- An updated python-mode.el version 4.1 which integrates Ken
1008 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
1009 much nicer in XEmacs and Emacs. When stepping through your program
1010 with pdb, in either the shell window or the *Python* window, the
1011 source file and line will be tracked by an arrow. Very cool!
1012
1013- IDLE: syntax warnings in interactive mode are changed into errors.
1014
1015- Some improvements to Tools/webchecker (ignore some more URL types,
Tim Peters0e57abf2001-05-02 07:39:38 +00001016 follow some more links).
Guido van Rossum5b08f132001-04-16 02:05:23 +00001017
1018- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +00001019
Barry Warsaw11e89c72001-04-11 20:37:57 +00001020
Martin v. Löwis0411f6f2001-03-21 08:01:39 +00001021What's New in Python 2.1 beta 2?
1022================================
1023
Guido van Rossum053ae352001-03-22 14:17:21 +00001024(Unlisted are many fixed bugs, more documentation, etc.)
1025
Martin v. Löwis0411f6f2001-03-21 08:01:39 +00001026Core language, builtins, and interpreter
1027
Guido van Rossum053ae352001-03-22 14:17:21 +00001028- The nested scopes work (enabled by "from __future__ import
1029 nested_scopes") is completed; in particular, the future now extends
1030 into code executed through exec, eval() and execfile(), and into the
1031 interactive interpreter.
1032
1033- When calling a base class method (e.g. BaseClass.__init__(self)),
1034 this is now allowed even if self is not strictly spoken a class
1035 instance (e.g. when using metaclasses or the Don Beaudry hook).
1036
1037- Slice objects are now comparable but not hashable; this prevents
1038 dict[:] from being accepted but meaningless.
1039
1040- Complex division is now calculated using less braindead algorithms.
1041 This doesn't change semantics except it's more likely to give useful
1042 results in extreme cases. Complex repr() now uses full precision
1043 like float repr().
1044
1045- sgmllib.py now calls handle_decl() for simple <!...> declarations.
1046
Jeremy Hyltonf626db72001-03-23 14:18:27 +00001047- It is illegal to assign to the name __debug__, which is set when the
1048 interpreter starts. It is effectively a compile-time constant.
1049
1050- A warning will be issued if a global statement for a variable
1051 follows a use or assignment of that variable.
1052
Martin v. Löwis0411f6f2001-03-21 08:01:39 +00001053Standard library
1054
Guido van Rossum053ae352001-03-22 14:17:21 +00001055- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
1056 inspired by JUnit), is now part of the standard library. You now
1057 have a choice of two testing frameworks: unittest requires you to
1058 write testcases as separate code, doctest gathers them from
1059 docstrings. Both approaches have their advantages and
1060 disadvantages.
1061
1062- A new module Tix was added, which wraps the Tix extension library
1063 for Tk. With that module, it is not necessary to statically link
1064 Tix with _tkinter, since Tix will be loaded with Tcl's "package
1065 require" command. See Demo/tix/.
1066
1067- tzparse.py is now obsolete.
1068
1069- In gzip.py, the seek() and tell() methods are removed -- they were
1070 non-functional anyway, and it's better if callers can test for their
1071 existence with hasattr().
1072
1073Python/C API
1074
1075- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
1076 that's already in the dictionary during a PyDict_Next() iteration.
1077 This used to fail occasionally when a dictionary resize operation
1078 could be triggered that would rehash all the keys. All other
1079 modifications to the dictionary are still off-limits during a
1080 PyDict_Next() iteration!
1081
1082- New extended APIs related to passing compiler variables around.
1083
1084- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
1085 implement isinstance() and issubclass().
1086
1087- Py_BuildValue() now has a "D" conversion to create a Python complex
1088 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +00001089
Fred Drake4e262a92001-03-22 18:26:47 +00001090- Extensions types which support weak references must now set the
1091 field allocated for the weak reference machinery to NULL themselves;
1092 this is done to avoid the cost of checking each object for having a
1093 weakly referencable type in PyObject_INIT(), since most types are
1094 not weakly referencable.
1095
Jeremy Hyltonf626db72001-03-23 14:18:27 +00001096- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
1097 free variables and cell variables to and from the frame's f_locals.
1098
1099- Variants of several functions defined in pythonrun.h have been added
1100 to support the nested_scopes future statement. The variants all end
1101 in Flags and take an extra argument, a PyCompilerFlags *; examples:
1102 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
1103 variants may be removed in Python 2.2, when nested scopes are
Tim Peters0e57abf2001-05-02 07:39:38 +00001104 mandatory.
Jeremy Hyltonf626db72001-03-23 14:18:27 +00001105
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001106Distutils
1107
1108- the sdist command now writes a PKG-INFO file, as described in PEP 241,
1109 into the release tree.
1110
Tim Peters0e57abf2001-05-02 07:39:38 +00001111- several enhancements to the bdist_wininst command from Thomas Heller
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001112 (an uninstaller, more customization of the installer's display)
1113
1114- from Jack Jansen: added Mac-specific code to generate a dialog for
1115 users to specify the command-line (because providing a command-line with
Tim Peters0e57abf2001-05-02 07:39:38 +00001116 MacPython is awkward). Jack also made various fixes for the Mac
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001117 and the Metrowerks compiler.
Tim Peters0e57abf2001-05-02 07:39:38 +00001118
1119- added 'platforms' and 'keywords' to the set of metadata that can be
1120 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +00001121
1122- applied patches from Jason Tishler to make the compiler class work with
1123 Cygwin.
1124
1125
Tim Peters2fe289a2001-03-01 22:19:38 +00001126What's New in Python 2.1 beta 1?
1127================================
Tim Petersd66595f2001-02-04 03:09:53 +00001128
1129Core language, builtins, and interpreter
1130
Guido van Rossum9d0fbde2001-03-02 14:00:32 +00001131- Following an outcry from the community about the amount of code
1132 broken by the nested scopes feature introduced in 2.1a2, we decided
1133 to make this feature optional, and to wait until Python 2.2 (or at
1134 least 6 months) to make it standard. The option can be enabled on a
1135 per-module basis by adding "from __future__ import nested_scopes" at
1136 the beginning of a module (before any other statements, but after
1137 comments and an optional docstring). See PEP 236 (Back to the
1138 __future__) for a description of the __future__ statement. PEP 227
1139 (Statically Nested Scopes) has been updated to reflect this change,
1140 and to clarify the semantics in a number of endcases.
1141
1142- The nested scopes code, when enabled, has been hardened, and most
1143 bugs and memory leaks in it have been fixed.
1144
1145- Compile-time warnings are now generated for a number of conditions
1146 that will break or change in meaning when nested scopes are enabled:
1147
1148 - Using "from...import *" or "exec" without in-clause in a function
1149 scope that also defines a lambda or nested function with one or
1150 more free (non-local) variables. The presence of the import* or
1151 bare exec makes it impossible for the compiler to determine the
1152 exact set of local variables in the outer scope, which makes it
1153 impossible to determine the bindings for free variables in the
1154 inner scope. To avoid the warning about import *, change it into
1155 an import of explicitly name object, or move the import* statement
1156 to the global scope; to avoid the warning about bare exec, use
1157 exec...in... (a good idea anyway -- there's a possibility that
1158 bare exec will be deprecated in the future).
1159
1160 - Use of a global variable in a nested scope with the same name as a
1161 local variable in a surrounding scope. This will change in
1162 meaning with nested scopes: the name in the inner scope will
1163 reference the variable in the outer scope rather than the global
1164 of the same name. To avoid the warning, either rename the outer
1165 variable, or use a global statement in the inner function.
1166
Neil Schemenauera35c6882001-02-27 04:45:05 +00001167- An optional object allocator has been included. This allocator is
1168 optimized for Python objects and should be faster and use less memory
1169 than the standard system allocator. It is not enabled by default
1170 because of possible thread safety problems. The allocator is only
1171 protected by the Python interpreter lock and it is possible that some
1172 extension modules require a thread safe allocator. The object
1173 allocator can be enabled by providing the "--with-pymalloc" option to
1174 configure.
1175
Tim Petersd66595f2001-02-04 03:09:53 +00001176Standard library
1177
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001178- pyexpat now detects the expat version if expat.h defines it. A
1179 number of additional handlers are provided, which are only available
1180 since expat 1.95. In addition, the methods SetParamEntityParsing and
1181 GetInputContext of Parser objects are available with 1.95.x
1182 only. Parser objects now provide the ordered_attributes and
1183 specified_attributes attributes. A new module expat.model was added,
1184 which offers a number of additional constants if 1.95.x is used.
1185
1186- xml.dom offers the new functions registerDOMImplementation and
1187 getDOMImplementation.
1188
1189- xml.dom.minidom offers a toprettyxml method. A number of DOM
1190 conformance issues have been resolved. In particular, Element now
1191 has an hasAttributes method, and the handling of namespaces was
1192 improved.
1193
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +00001194- Ka-Ping Yee contributed two new modules: inspect.py, a module for
1195 getting information about live Python code, and pydoc.py, a module
1196 for interactively converting docstrings to HTML or text.
1197 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +00001198 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +00001199 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
1200 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +00001201
Tim Peters1eff7962001-03-01 02:31:33 +00001202- New library module difflib.py, primarily packaging the SequenceMatcher
1203 class at the heart of the popular ndiff.py file-comparison tool.
1204
1205- doctest.py (a framework for verifying Python code examples in docstrings)
1206 is now part of the std library.
1207
Tim Petersd66595f2001-02-04 03:09:53 +00001208Windows changes
1209
Guido van Rossume3955a82001-03-02 14:05:59 +00001210- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
1211 small GUI that lets you browse the module docstrings using your
1212 default web browser.
1213
Tim Peters1eff7962001-03-01 02:31:33 +00001214- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
1215 Platforms) is implemented. See
1216
1217 http://python.sourceforge.net/peps/pep-0235.html
1218
1219 for full details, especially the "Current Lower-Left Semantics" section.
1220 The new Windows import rules are simpler than before:
1221
1222 A. If the PYTHONCASEOK environment variable exists, same as
1223 before: silently accept the first case-insensitive match of any
1224 kind; raise ImportError if none found.
1225
1226 B. Else search sys.path for the first case-sensitive match; raise
1227 ImportError if none found.
1228
1229 The same rules have been implented on other platforms with case-
1230 insensitive but case-preserving filesystems too (including Cygwin, and
1231 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +00001232
Tim Peters25a9ce32001-02-19 07:06:36 +00001233- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
1234 what it's supposed to do (and does do under NT and 2000) via direct
1235 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +00001236 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +00001237 all Win9x systems before.
1238
Tim Peters1eff7962001-03-01 02:31:33 +00001239- Build: Subproject _test (effectively) renamed to _testcapi.
1240
Tim Peters2fe289a2001-03-01 22:19:38 +00001241New platforms
1242
1243- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
1244 Thanks to Steven Majewski!
1245
1246- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
1247 Tishler!
1248
Guido van Rossum9089b272001-03-02 06:49:50 +00001249- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
1250 Schwertberger! See RISCOS/README for more information -- it seems
1251 that because of the bizarre filename conventions on RISCOS, no port
1252 to that platform is easy. Note that the new variable os.endsep is
1253 silently supported in order to make life easier on this platform,
1254 but we don't advertise it because it's not worth for most folks to
1255 care about RISCOS portability.
1256
Tim Peters25a9ce32001-02-19 07:06:36 +00001257
Tim Petersd7b5e882001-01-25 03:36:26 +00001258What's New in Python 2.1 alpha 2?
1259=================================
Tim Peters40ead762001-01-27 05:35:26 +00001260
Tim Petersd7b5e882001-01-25 03:36:26 +00001261Core language, builtins, and interpreter
1262
Jeremy Hylton4589bd82001-02-01 20:38:45 +00001263- Scopes nest. If a name is used in a function or class, but is not
1264 local, the definition in the nearest enclosing function scope will
1265 be used. One consequence of this change is that lambda statements
1266 could reference variables in the namespaces where the lambda is
1267 defined. In some unusual cases, this change will break code.
1268
1269 In all previous version of Python, names were resolved in exactly
1270 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001271 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +00001272 function A is defined within a function B, the names bound in B are
1273 not visible in A. The new rules make names bound in B visible in A,
1274 unless A contains a name binding that hides the binding in B.
1275
1276 Section 4.1 of the reference manual describes the new scoping rules
1277 in detail. The test script in Lib/test/test_scope.py demonstrates
1278 some of the effects of the change.
1279
1280 The new rules will cause existing code to break if it defines nested
1281 functions where an outer function has local variables with the same
1282 name as globals or builtins used by the inner function. Example:
1283
1284 def munge(str):
1285 def helper(x):
1286 return str(x)
1287 if type(str) != type(''):
1288 str = helper(str)
1289 return str.strip()
1290
1291 Under the old rules, the name str in helper() is bound to the
1292 builtin function str(). Under the new rules, it will be bound to
1293 the argument named str and an error will occur when helper() is
1294 called.
1295
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001296- The compiler will report a SyntaxError if "from ... import *" occurs
1297 in a function or class scope. The language reference has documented
1298 that this case is illegal, but the compiler never checked for it.
1299 The recent introduction of nested scope makes the meaning of this
1300 form of name binding ambiguous. In a future release, the compiler
1301 may allow this form when there is no possibility of ambiguity.
1302
Tim Peters40ead762001-01-27 05:35:26 +00001303- repr(string) is easier to read, now using hex escapes instead of octal,
1304 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
1305
1306 >>> "\texample \r\n" + chr(0) + chr(255)
1307 '\texample \r\n\x00\xff' # in 2.1
1308 '\011example \015\012\000\377' # in 2.0
1309
Moshe Zadka6af0ce02001-01-29 06:41:00 +00001310- Functions are now compared and hashed by identity, not by value, since
1311 the func_code attribute is writable.
1312
Fred Drakefb9d7122001-02-01 20:00:40 +00001313- Weak references (PEP 205) have been added. This involves a few
1314 changes in the core, an extension module (_weakref), and a Python
1315 module (weakref). The weakref module is the public interface. It
1316 includes support for "explicit" weak references, proxy objects, and
1317 mappings with weakly held values.
1318
Jeremy Hylton0072d5a2001-02-01 22:53:15 +00001319- A 'continue' statement can now appear in a try block within the body
1320 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +00001321 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +00001322
Tim Petersd7b5e882001-01-25 03:36:26 +00001323Standard library
1324
Barry Warsaw30dbd142001-01-31 22:14:01 +00001325- mailbox.py now has a new class, PortableUnixMailbox which is
1326 identical to UnixMailbox but uses a more portable scheme for
1327 determining From_ separators. Also, the constructors for all the
1328 classes in this module have a new optional `factory' argument, which
1329 is a callable used when new message classes must be instantiated by
1330 the next() method.
1331
Tim Petersd7b5e882001-01-25 03:36:26 +00001332- random.py is now self-contained, and offers all the functionality of
1333 the now-deprecated whrandom.py. See the docs for details. random.py
1334 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +00001335 and restoring the internal state of the generator; and jumpahead(n),
1336 for quickly forcing the internal state to be the same as if n calls to
1337 random() had been made. The latter is particularly useful for multi-
1338 threaded programs, creating one instance of the random.Random() class for
1339 each thread, then using .jumpahead() to force each instance to use a
1340 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +00001341
Tim Peters0de88fc2001-02-01 04:59:18 +00001342- random.py's seed() function is new. For bit-for-bit compatibility with
1343 prior releases, use the whseed function instead. The new seed function
1344 addresses two problems: (1) The old function couldn't produce more than
1345 about 2**24 distinct internal states; the new one about 2**45 (the best
1346 that can be done in the Wichmann-Hill generator). (2) The old function
1347 sometimes produced identical internal states when passed distinct
1348 integers, and there was no simple way to predict when that would happen;
1349 the new one guarantees to produce distinct internal states for all
1350 arguments in [0, 27814431486576L).
1351
Jeremy Hylton4c4fda02001-02-02 03:29:24 +00001352- The socket module now supports raw packets on Linux. The socket
1353 family is AF_PACKET.
1354
Tim Peters9ea17ac2001-02-02 05:57:15 +00001355- test_capi.py is a start at running tests of the Python C API. The tests
1356 are implemented by the new Modules/_testmodule.c.
1357
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +00001358- A new extension module, _symtable, provides provisional access to the
1359 internal symbol table used by the Python compiler. A higher-level
1360 interface will be added on top of _symtable in a future release.
1361
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +00001362- Removed the obsolete soundex module.
1363
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001364- xml.dom.minidom now uses the standard DOM exceptions. Node supports
1365 the isSameNode method; NamedNodeMap the get method.
1366
1367- xml.sax.expatreader supports the lexical handler property; it
1368 generates comment, startCDATA, and endCDATA events.
1369
Tim Petersee826f82001-01-31 19:39:44 +00001370Windows changes
1371
1372- Build procedure: the zlib project is built in a different way that
1373 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +00001374 the zlib binary used. See PCbuild\readme.txt for details. Your old
1375 zlib-related directories can be deleted; you'll need to download fresh
1376 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +00001377
Tim Peters9ea17ac2001-02-02 05:57:15 +00001378- Build: New subproject _test for the benefit of test_capi.py (see above).
1379
Tim Petersb16c56f2001-02-02 21:24:51 +00001380- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
1381 interface to some Python compiler internals).
1382
1383- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +00001384 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +00001385
Tim Petersa3a3a032000-11-30 05:22:44 +00001386What's New in Python 2.1 alpha 1?
1387=================================
1388
1389Core language, builtins, and interpreter
1390
Marc-André Lemburgebb195b2001-01-20 10:34:52 +00001391- There is a new Unicode companion to the PyObject_Str() API
1392 called PyObject_Unicode(). It behaves in the same way as the
1393 former, but assures that the returned value is an Unicode object
1394 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +00001395
Guido van Rossumf98eda02001-01-17 15:54:45 +00001396- The comparison operators support "rich comparison overloading" (PEP
1397 207). C extension types can provide a rich comparison function in
1398 the new tp_richcompare slot in the type object. The cmp() function
1399 and the C function PyObject_Compare() first try the new rich
1400 comparison operators before trying the old 3-way comparison. There
1401 is also a new C API PyObject_RichCompare() (which also falls back on
1402 the old 3-way comparison, but does not constrain the outcome of the
1403 rich comparison to a Boolean result).
1404
1405 The rich comparison function takes two objects (at least one of
1406 which is guaranteed to have the type that provided the function) and
1407 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
1408 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
1409 object, which may be NotImplemented (in which case the tp_compare
1410 slot function is used as a fallback, if defined).
1411
1412 Classes can overload individual comparison operators by defining one
1413 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +00001414 __ge__. There are no explicit "reflected argument" versions of
1415 these; instead, __lt__ and __gt__ are each other's reflection,
1416 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
1417 reflection (similar at the C level). No other implications are
1418 made; in particular, Python does not assume that == is the Boolean
1419 inverse of !=, or that < is the Boolean inverse of >=. This makes
1420 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +00001421
1422 Classes or types that want to implement (in)equality tests but not
1423 the ordering operators (i.e. unordered types) should implement ==
1424 and !=, and raise an error for the ordering operators.
1425
Guido van Rossuma88479f2001-01-18 14:28:08 +00001426 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +00001427 Boolean; e.g. a matrix type might want to return a matrix of bits
1428 for A < B, giving elementwise comparisons. Such types should ensure
1429 that any interpretation of their value in a Boolean context raises
1430 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
1431 at the C level) to always raise an exception.
1432
Guido van Rossuma88479f2001-01-18 14:28:08 +00001433- Complex numbers use rich comparisons to define == and != but raise
1434 an exception for <, <=, > and >=. Unfortunately, this also means
1435 that cmp() of two complex numbers raises an exception when the two
1436 numbers differ. Since it is not mathematically meaningful to compare
1437 complex numbers except for equality, I hope that this doesn't break
1438 too much code.
1439
Tim Peters3389f192001-02-18 08:48:49 +00001440- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +00001441 not defined by the language, other than that it's arbitrary but
1442 consistent (see the Reference Manual). An implementation detail changed
1443 in 2.1a1 such that None now compares less than any other object. Code
1444 relying on this new behavior (like code that relied on the previous
1445 behavior) does so at its own risk.
1446
Barry Warsaw573b5412001-01-15 20:43:18 +00001447- Functions and methods now support getting and setting arbitrarily
1448 named attributes (PEP 232). Functions have a new __dict__
1449 (a.k.a. func_dict) which hold the function attributes. Methods get
1450 and set attributes on their underlying im_func. It is a TypeError
1451 to set an attribute on a bound method.
1452
Guido van Rossum051e3352001-01-15 19:11:10 +00001453- The xrange() object implementation has been improved so that
1454 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
1455 limitation that in this case len(xrange(sys.maxint)) can't be
1456 calculated, but the common idiom "for i in xrange(sys.maxint)" will
1457 work fine as long as the index i doesn't actually reach 2**31.
1458 (Python uses regular ints for sequence and string indices; fixing
1459 that is much more work.)
1460
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001461- Two changes to from...import:
1462
Guido van Rossumba381232001-02-03 15:06:40 +00001463 1) "from M import X" now works even if (after loading module M)
1464 sys.modules['M'] is not a real module; it's basically a getattr()
1465 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +00001466
1467 2) "from M import *" now looks for M.__all__ to decide which names to
1468 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
1469 filters out names starting with '_' as before. Whether or not
1470 __all__ exists, there's no restriction on the type of M.
1471
Guido van Rossumf61f1662001-01-10 20:13:55 +00001472- File objects have a new method, xreadlines(). This is the fastest
1473 way to iterate over all lines in a file:
1474
1475 for line in file.xreadlines():
1476 ...do something to line...
1477
1478 See the xreadlines module (mentioned below) for how to do this for
1479 other file-like objects.
1480
1481- Even if you don't use file.xreadlines(), you may expect a speedup on
1482 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +00001483 quite a bit in platform-specific ways: on systems (like Linux) that
1484 support flockfile(), getc_unlocked(), and funlockfile(), those are
1485 used by default. On systems (like Windows) without getc_unlocked(),
1486 a complicated (but still thread-safe) method using fgets() is used by
1487 default.
1488
Tim Petersd52269b2001-01-25 06:23:18 +00001489 You can force use of the fgets() method by #define'ing
1490 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +00001491 getc_unlocked()).
1492
Tim Petersd52269b2001-01-25 06:23:18 +00001493 You can force fgets() not to be used by #define'ing
1494 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +00001495 test_bufio.py fails -- and let us know if it does!).
1496
1497- In addition, the fileinput module, while still slower than the other
1498 methods on most platforms, has been sped up too, by using
1499 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001500
1501- Support for run-time warnings has been added, including a new
1502 command line option (-W) to specify the disposition of warnings.
1503 See the description of the warnings module below.
1504
1505- Extensive changes have been made to the coercion code. This mostly
1506 affects extension modules (which can now implement mixed-type
1507 numerical operators without having to use coercion), but
1508 occasionally, in boundary cases the coercion semantics have changed
1509 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +00001510 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +00001511 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +00001512 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +00001513
Guido van Rossumf98eda02001-01-17 15:54:45 +00001514- In connection with the coercion changes, a new built-in singleton
1515 object, NotImplemented is defined. This can be returned for
1516 operations that wish to indicate they are not implemented for a
1517 particular combination of arguments. From C, this is
1518 Py_NotImplemented.
1519
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001520- The interpreter accepts now bytecode files on the command line even
1521 if they do not have a .pyc or .pyo extension. On Linux, after executing
1522
Martin v. Löwise214baa2001-02-04 22:37:56 +00001523import imp,sys,string
1524magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
1525reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
1526open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +00001527
1528 any byte code file can be used as an executable (i.e. as an argument
1529 to execve(2)).
1530
Tim Peters9940b802000-12-01 07:59:35 +00001531- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +00001532 character. In 1.6 and earlier, they never produced a sign,
1533 and raised an error if the value of the long was too large
1534 to fit in a Python int. In 2.0, they produced a sign if and
1535 only if too large to fit in an int. This was inconsistent
1536 across platforms (because the size of an int varies across
1537 platforms), and inconsistent with hex() and oct(). Example:
1538
1539 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +00001540 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +00001541 'ffffffbe' # in 2.0 and before, on 32-bit machines
1542 >>> hex(-0x42L)
1543 '-0x42L' # in all versions of Python
1544
Tim Peters9940b802000-12-01 07:59:35 +00001545 The behavior of %d formats for negative Python longs remains
1546 the same as in 2.0 (although in 1.6 and before, they raised
1547 an error if the long didn't fit in a Python int).
1548
1549 %u formats don't make sense for Python longs, but are allowed
1550 and treated the same as %d in 2.1. In 2.0, a negative long
1551 formatted via %u produced a sign if and only if too large to
1552 fit in an int. In 1.6 and earlier, a negative long formatted
1553 via %u raised an error if it was too big to fit in an int.
1554
Guido van Rossum3661d392000-12-12 22:10:31 +00001555- Dictionary objects have an odd new method, popitem(). This removes
1556 an arbitrary item from the dictionary and returns it (in the form of
1557 a (key, value) pair). This can be useful for algorithms that use a
1558 dictionary as a bag of "to do" items and repeatedly need to pick one
1559 item. Such algorithms normally end up running in quadratic time;
1560 using popitem() they can usually be made to run in linear time.
1561
Tim Peters36cdad12000-12-29 02:06:45 +00001562Standard library
1563
Thomas Woutersfe385252001-01-19 23:16:56 +00001564- In the time module, the time argument to the functions strftime,
1565 localtime, gmtime, asctime and ctime is now optional, defaulting to
1566 the current time (in the local timezone).
1567
Guido van Rossumda91f222001-01-15 16:36:08 +00001568- The ftplib module now defaults to passive mode, which is deemed a
1569 more useful default given that clients are often inside firewalls
1570 these days. Note that this could break if ftplib is used to connect
1571 to a *server* that is inside a firewall, from outside; this is
1572 expected to be a very rare situation. To fix that, you can call
1573 ftp.set_pasv(0).
1574
Martin v. Löwis10a27872001-01-13 09:54:41 +00001575- The module site now treats .pth files not only for path configuration,
1576 but also supports extensions to the initialization code: Lines starting
1577 with import are executed.
1578
Guido van Rossumf61f1662001-01-10 20:13:55 +00001579- There's a new module, warnings, which implements a mechanism for
1580 issuing and filtering warnings. There are some new built-in
1581 exceptions that serve as warning categories, and a new command line
1582 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
1583 turns warnings into errors). warnings.warn(message[, category])
1584 issues a warning message; this can also be called from C as
1585 PyErr_Warn(category, message).
1586
1587- A new module xreadlines was added. This exports a single factory
1588 function, xreadlines(). The intention is that this code is the
1589 absolutely fastest way to iterate over all lines in an open
1590 file(-like) object:
1591
1592 import xreadlines
1593 for line in xreadlines.xreadlines(file):
1594 ...do something to line...
1595
1596 This is equivalent to the previous the speed record holder using
1597 file.readlines(sizehint). Note that if file is a real file object
1598 (as opposed to a file-like object), this is equivalent:
1599
1600 for line in file.xreadlines():
1601 ...do something to line...
1602
Tim Peters36cdad12000-12-29 02:06:45 +00001603- The bisect module has new functions bisect_left, insort_left,
1604 bisect_right and insort_right. The old names bisect and insort
1605 are now aliases for bisect_right and insort_right. XXX_right
1606 and XXX_left methods differ in what happens when the new element
1607 compares equal to one or more elements already in the list: the
1608 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +00001609 right. Code that doesn't care where equal elements end up should
1610 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +00001611
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +00001612- The new curses.panel module wraps the panel library that forms part
1613 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
1614
Guido van Rossumf61f1662001-01-10 20:13:55 +00001615- The SocketServer module now sets the allow_reuse_address flag by
1616 default in the TCPServer class.
1617
1618- A new function, sys._getframe(), returns the stack frame pointer of
1619 the caller. This is intended only as a building block for
1620 higher-level mechanisms such as string interpolation.
1621
Martin v. Löwis2a5130e2001-02-27 04:21:58 +00001622- The pyexpat module supports a number of new handlers, which are
1623 available only in expat 1.2. If invocation of a callback fails, it
1624 will report an additional frame in the traceback. Parser objects
1625 participate now in garbage collection. If expat reports an unknown
1626 encoding, pyexpat will try to use a Python codec; that works only
1627 for single-byte charsets. The parser type objects is exposed as
1628 XMLParserObject.
1629
1630- xml.dom now offers standard definitions for symbolic node type and
1631 exception code constants, and a hierarchy of DOM exceptions. minidom
1632 was adjusted to use them.
1633
1634- The conformance of xml.dom.minidom to the DOM specification was
1635 improved. It detects a number of additional error cases; the
1636 previous/next relationship works even when the tree is modified;
1637 Node supports the normalize() method; NamedNodeMap, DocumentType and
1638 DOMImplementation classes were added; Element supports the
1639 hasAttribute and hasAttributeNS methods; and Text supports the splitText
1640 method.
1641
Guido van Rossumf61f1662001-01-10 20:13:55 +00001642Build issues
1643
Guido van Rossum1e33bdc2001-01-23 03:17:00 +00001644- For Unix (and Unix-compatible) builds, configuration and building of
1645 extension modules is now greatly automated. Rather than having to
1646 edit the Modules/Setup file to indicate which modules should be
1647 built and where their include files and libraries are, a
1648 distutils-based setup.py script now takes care of building most
1649 extension modules. All extension modules built this way are built
1650 as shared libraries. Only a few modules that must be linked
1651 statically are still listed in the Setup file; you won't need to
1652 edit their configuration.
1653
1654- Python should now build out of the box on Cygwin. If it doesn't,
1655 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +00001656
1657- Python now always uses its own (renamed) implementation of getopt()
1658 -- there's too much variation among C library getopt()
1659 implementations.
1660
1661- C++ compilers are better supported; the CXX macro is always set to a
1662 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +00001663
Tim Petersd92dfe02000-12-12 01:18:41 +00001664Windows changes
1665
1666- select module: By default under Windows, a select() call
1667 can specify no more than 64 sockets. Python now boosts
1668 this Microsoft default to 512. If you need even more than
1669 that, see the MS docs (you'll need to #define FD_SETSIZE
1670 and recompile Python from source).
1671
Guido van Rossumf61f1662001-01-10 20:13:55 +00001672- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
1673 subdirectory is no more!
1674
Tim Petersa3a3a032000-11-30 05:22:44 +00001675
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001676What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +00001677=========================
Guido van Rossum61000331997-08-15 04:39:58 +00001678
Guido van Rossum8ed602b2000-09-01 22:34:33 +00001679Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001680changes are in the file HISTORY. If you are making the jump directly
1681from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
1682HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +00001683
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001684Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
1685the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
1686http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +00001687
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001688--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +00001689
1690======================================================================
1691
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001692What's new in 2.0 (since release candidate 1)?
1693==============================================
1694
1695Standard library
1696
1697- The copy_reg module was modified to clarify its intended use: to
1698 register pickle support for extension types, not for classes.
1699 pickle() will raise a TypeError if it is passed a class.
1700
1701- Fixed a bug in gettext's "normalize and expand" code that prevented
1702 it from finding an existing .mo file.
1703
1704- Restored support for HTTP/0.9 servers in httplib.
1705
Tim Peters989b7b92000-10-16 20:24:53 +00001706- The math module was changed to stop raising OverflowError in case of
1707 underflow, and return 0 instead in underflow cases. Whether Python
1708 used to raise OverflowError in case of underflow was platform-
1709 dependent (it did when the platform math library set errno to ERANGE
1710 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001711
1712- Fixed a bug in StringIO that occurred when the file position was not
1713 at the end of the file and write() was called with enough data to
1714 extend past the end of the file.
1715
1716- Fixed a bug that caused Tkinter error messages to get lost on
1717 Windows. The bug was fixed by replacing direct use of
1718 interp->result with Tcl_GetStringResult(interp).
1719
1720- Fixed bug in urllib2 that caused it to fail when it received an HTTP
1721 redirect response.
1722
1723- Several changes were made to distutils: Some debugging code was
1724 removed from util. Fixed the installer used when an external zip
1725 program (like WinZip) is not found; the source code for this
1726 installer is in Misc/distutils. check_lib() was modified to behave
1727 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
1728 test for whether installed modules are on sys.path was changed to
1729 use both normcase() and normpath().
1730
Jeremy Hyltond867a2c2000-10-16 20:41:38 +00001731- Several minor bugs were fixed in the xml package (the minidom,
1732 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001733
1734- The regression test driver (regrtest.py) behavior when invoked with
1735 -l changed: It now reports a count of objects that are recognized as
1736 garbage but not freed by the garbage collector.
1737
Tim Peters989b7b92000-10-16 20:24:53 +00001738- The regression test for the math module was changed to test
1739 exceptional behavior when the test is run in verbose mode. Python
1740 cannot yet guarantee consistent exception behavior across platforms,
1741 so the exception part of test_math is run only in verbose mode, and
1742 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001743
1744Internals
1745
1746- PyOS_CheckStack() has been disabled on Win64, where it caused
1747 test_sre to fail.
1748
1749Build issues
1750
1751- Changed compiler flags, so that gcc is always invoked with -Wall and
1752 -Wstrict-prototypes. Users compiling Python with GCC should see
1753 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +00001754 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +00001755 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001756
Tim Petersa3a3a032000-11-30 05:22:44 +00001757- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001758
1759Tools and other miscellany
1760
1761- The compiler in Tools/compiler was updated to support the new
1762 language features introduced in 2.0: extended print statement, list
1763 comprehensions, and augmented assignments. The new compiler should
1764 also be backwards compatible with Python 1.5.2; the compiler will
1765 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +00001766 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001767
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001768What's new in 2.0 release candidate 1 (since beta 2)?
1769=====================================================
1770
Jeremy Hylton6040aaa2000-10-09 21:27:22 +00001771What is release candidate 1?
1772
1773We believe that release candidate 1 will fix all known bugs that we
1774intend to fix for the 2.0 final release. This release should be a bit
1775more stable than the previous betas. We would like to see even more
1776widespread testing before the final release, so we are producing this
1777release candidate. The final release will be exactly the same unless
1778any show-stopping (or brown bag) bugs are found by testers of the
1779release candidate.
1780
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001781All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001782to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001783
1784Core language, builtins, and interpreter
1785
1786- A bug that caused crashes when __coerce__ was used with augmented
1787 assignment, e.g. +=, was fixed.
1788
1789- Raise ZeroDivisionError when raising zero to a negative number,
1790 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
1791 power operator and the result of math.pow(0.0, -2.0) will vary by
1792 platform. On Linux, it raises a ValueError.
1793
1794- A bug in Unicode string interpolation was fixed that occasionally
1795 caused errors with formats including "%%". For example, the
1796 following expression "%% %s" % u"abc" no longer raises a TypeError.
1797
1798- Compilation of deeply nested expressions raises MemoryError instead
1799 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1800
1801- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1802 rendering them useless. They are now written in binary mode again.
1803
1804Standard library
1805
1806- Keyword arguments are now accepted for most pattern and match object
1807 methods in SRE, the standard regular expression engine.
1808
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001809- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001810 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001811
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001812- Several bugs in the Unicode handling and error handling in _tkinter
1813 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001814
1815- Fix memory management errors in Merge() and Tkapp_Call() routines.
1816
1817- Several changes were made to cStringIO to make it compatible with
1818 the file-like object interface and with StringIO. If operations are
1819 performed on a closed object, an exception is raised. The truncate
1820 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001821 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001822
1823- There were many changes made to the linuxaudiodev module and its
1824 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001825 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001826
1827 Note that this module is named poorly, because it should work
1828 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001829 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001830
1831 The module now raises exceptions when errors occur instead of
1832 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1833 audio) and defines a getptr() method that calls the
1834 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1835
1836- The library_version attribute, introduced in an earlier beta, was
1837 removed because it can not be supported with early versions of the C
1838 readline library, which provides no way to determine the version at
1839 compile-time.
1840
1841- The binascii module is now enabled on Win64.
1842
Tim Peters46446d62000-10-09 21:19:31 +00001843- tokenize.py no longer suffers "recursion depth" errors when parsing
1844 programs with very long string literals.
1845
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001846Internals
1847
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001848- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001849 which is called when the interpreter starts up to determine where
1850 the standard library is installed. These vulnerabilities affect all
1851 previous versions of Python and can be exploited by setting very
1852 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1853 setuid Python script, although use of the wrapper in
1854 Misc/setuid-prog.c will eliminate the vulnerability.
1855
1856- Fixed garbage collection bugs in instance creation that were
1857 triggered when errors occurred during initialization. The solution,
1858 applied in cPickle and in PyInstance_New(), is to call
1859 PyObject_GC_Init() after the initialization of the object's
1860 container attributes is complete.
1861
1862- pyexpat adds definitions of PyModule_AddStringConstant and
1863 PyModule_AddObject if the Python version is less than 2.0, which
1864 provides compatibility with PyXML on Python 1.5.2.
1865
1866- If the platform has a bogus definition for LONG_BIT (the number of
1867 bits in a long), an error will be reported at compile time.
1868
1869- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1870 collection crashes and possibly other, unreported crashes.
1871
1872- Fixed a memory leak in _PyUnicode_Fini().
1873
1874Build issues
1875
1876- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001877 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001878 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001879
1880- The mmap.PAGESIZE constant is now initialized using sysconf when
1881 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1882
1883- The md5 file should now compile on all platforms.
1884
1885- The select module now compiles on platforms that do not define
1886 POLLRDNORM and related constants.
1887
1888- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001889 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001890
Jeremy Hylton10921202000-10-09 18:34:12 +00001891- BeOS: A number of changes were made to the build and installation
1892 process. ar-fake now operates on a directory of object files.
1893 dl_export.h is gone, and its macros now appear on the mwcc command
1894 line during build on PPC BeOS.
1895
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001896- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001897 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001898
1899- Cygwin: Support for shared libraries, Tkinter, and sockets.
1900
1901- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1902
1903Tools and other miscellany
1904
1905- Removed debugging prints from main used with freeze.
1906
Tim Peters46446d62000-10-09 21:19:31 +00001907- IDLE auto-indent no longer crashes when it encounters Unicode
1908 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001909
1910What's new in 2.0 beta 2 (since beta 1)?
1911========================================
1912
1913Core language, builtins, and interpreter
1914
Tim Peters482c0212000-09-26 06:33:09 +00001915- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001916 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001917
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001918- Add -h and -V command line options to print the usage message and
1919 Python version number and exit immediately.
1920
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001921- eval() and exec accept Unicode objects as code parameters.
1922
1923- getattr() and setattr() now also accept Unicode objects for the
1924 attribute name, which are converted to strings using the default
1925 encoding before lookup.
1926
1927- Multiplication on string and Unicode now does proper bounds
1928 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1929 string is too long."
1930
1931- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001932 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001933
Jeremy Hylton1b618592000-09-26 05:32:36 +00001934
1935Standard library and extensions
1936
Guido van Rossum5b08f132001-04-16 02:05:23 +00001937- socket module: the OpenSSL code now adds support for RAND_status()
1938 and EGD (Entropy Gathering Device).
1939
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001940- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001941 argument checking; it still takes no arguments.
1942
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001943- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001944
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001945- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001946
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001947- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001948
1949- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001950 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001951
1952- copy: Copy Unicode objects atomically.
1953
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001954- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001955
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001956- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001957
Fred Drake67233bc2000-09-26 16:40:27 +00001958- dbm: Add get() and setdefault() methods to dbm object. Add constant
1959 `library' to module that names the library used. Added doc strings
1960 and method names to error messages. Uses configure to determine
1961 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1962 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001963
1964- distutils: Update to version 0.9.3.
1965
1966- dl: Add several dl.RTLD_ constants.
1967
1968- fpectl: Now supported on FreeBSD.
1969
1970- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1971 found by the collector will be saved in gc.garbage. This is useful
1972 for debugging a program that creates reference cycles.
1973
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001974- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001975 of HTTP class. Do not close socket on zero-length response. Do not
1976 crash when server sends invalid content-length header.
1977
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001978- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001979
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001980- marshal: When reading a short, sign-extend on platforms where shorts
1981 are bigger than 16 bits. When reading a long, repair the unportable
1982 sign extension that was being done for 64-bit machines. (It assumed
1983 that signed right shift sign-extends.)
1984
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001985- operator: Add contains(), invert(), __invert__() as aliases for
1986 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001987
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001988- os: Add support for popen2() and popen3() on all platforms where
1989 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001990
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001991- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001992 clicking on a file in Explorer (or passing the file name to the
1993 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001994
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001995- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001996 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001997
1998- pickle: Now raises ValueError when an invalid pickle that contains
1999 a non-string repr where a string repr was expected. This behavior
2000 matches cPickle.
2001
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002002- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002003
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002004- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002005
2006- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002007 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002008 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00002009
2010- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002011 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002012
2013- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00002014 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00002015 few cycles during startup since the first call to
2016 setdefaultencoding() will initialize the codec registry and the
2017 encodings package.
2018
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002019- socket: Support for size hint in readlines() method of object returned
2020 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00002021
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002022- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00002023 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00002024 is followed by whitespace.
2025
Tim Petersa3a3a032000-11-30 05:22:44 +00002026- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002027
2028- struct: Check ranges for bytes and shorts.
2029
2030- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002031 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002032
2033- Tkinter: Image objects are now guaranteed to have unique ids. Set
2034 event.delta to zero if Tk version doesn't support mousewheel.
2035 Removed some debugging prints.
2036
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002037- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00002038
Fred Drake67233bc2000-09-26 16:40:27 +00002039- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002040 which works around a bug in Norton AntiVirus 2000 that leads directly
2041 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002042
2043- xml: New version detection code allows PyXML to override standard
2044 XML package if PyXML version is greater than 0.6.1.
2045
Fred Drake64bb3802000-09-26 16:21:35 +00002046- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
2047 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
2048 tree only for nodes which are sufficiently interesting to a specific
2049 application. Does not provide the HTML-specific extensions. Still
2050 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002051
Fred Drake64bb3802000-09-26 16:21:35 +00002052- xml.sax: SAX 2 support for Python, including all the handler
2053 interfaces needed to process XML 1.0 compliant XML. Some
2054 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002055
Fred Drake64bb3802000-09-26 16:21:35 +00002056- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
2057 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002058
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002059
Jeremy Hylton1b618592000-09-26 05:32:36 +00002060C API
2061
2062- Add three new convenience functions for module initialization --
2063 PyModule_AddObject(), PyModule_AddIntConstant(), and
2064 PyModule_AddStringConstant().
2065
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002066- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00002067 removed and add #error to Python.h if NULL isn't defined after
2068 #include of stdio.h.
2069
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002070- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00002071 backwards compatibility (at the source level) with old extensions.
2072
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002073- A wrapper API was added for signal() and sigaction(). Instead of
2074 either function, always use PyOS_getsig() to get a signal handler
2075 and PyOS_setsig() to set one. A new convenience typedef
2076 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002077
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002078- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00002079 internal data buffer and size of a string object -- or the default
2080 encoded version of a Unicode object.
2081
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002082- PyString_Size() and PyString_AsString() accept Unicode objects.
2083
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002084- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00002085 exists). INT_MAX and LONG_MAX will always be defined, even if
2086 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002087
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002088- PyFloat_FromString takes a second argument, pend, that was
2089 effectively useless. It is now officially useless but preserved for
2090 backwards compatibility. If the pend argument is not NULL, *pend is
2091 set to NULL.
2092
2093- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
2094 for the attribute name. See note on getattr() above.
2095
2096- A few bug fixes to argument processing for Unicode.
2097 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
2098 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
2099 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00002100 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002101
2102- Py_BuildValue accepts B format (for bgen-generated code).
2103
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002104
Jeremy Hylton1b618592000-09-26 05:32:36 +00002105Internals
2106
2107- On Unix, fix code for finding Python installation directory so that
2108 it works when argv[0] is a relative path.
2109
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00002110- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002111 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00002112 rather than by generating a copy of the object.
2113
Tim Peters482c0212000-09-26 06:33:09 +00002114- Several of the internal Unicode tables are much smaller now, and
2115 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002116
Jeremy Hylton97693b02000-09-26 17:42:51 +00002117- In the garbage collector: Fixed bug in collection of tuples. Fixed
2118 bug that caused some instances to be removed from the container set
2119 while they were still live. Fixed parsing in gc.set_debug() for
2120 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002121
2122- Fixed refcount problem in instance deallocation that only occurred
2123 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
2124
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002125- On Windows, getpythonregpath is now protected against null data in
2126 registry key.
2127
2128- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00002129 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002130
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002131
Jeremy Hylton1b618592000-09-26 05:32:36 +00002132Build and platform-specific issues
2133
2134- Better support of GNU Pth via --with-pth configure option.
2135
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002136- Python/C API now properly exposed to dynamically-loaded extension
2137 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00002138
2139- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
2140 Don't define MS_SYNC to be zero when it is undefined. Added missing
2141 prototypes in posixmodule.c.
2142
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002143- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002144 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00002145
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002146- Fix largefile support on older NetBSD systems and OpenBSD by adding
2147 define for TELL64.
2148
2149
2150Tools and other miscellany
2151
2152- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
2153
2154- freeze: The modulefinder now works with 2.0 opcodes.
2155
Tim Petersa3a3a032000-11-30 05:22:44 +00002156- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00002157 Move hackery of sys.argv until after the Tk instance has been
2158 created, which allows the application-specific Tkinter
2159 initialization to be executed if present; also pass an explicit
2160 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00002161
Jeremy Hylton1b618592000-09-26 05:32:36 +00002162
2163What's new in 2.0 beta 1?
2164=========================
2165
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002166Source Incompatibilities
2167------------------------
2168
2169None. Note that 1.6 introduced several incompatibilities with 1.5.2,
2170such as single-argument append(), connect() and bind(), and changes to
2171str(long) and repr(float).
2172
2173
2174Binary Incompatibilities
2175------------------------
2176
2177- Third party extensions built for Python 1.5.x or 1.6 cannot be used
2178with Python 2.0; these extensions will have to be rebuilt for Python
21792.0.
2180
2181- On Windows, attempting to import a third party extension built for
2182Python 1.5.x or 1.6 results in an immediate crash; there's not much we
2183can do about this. Check your PYTHONPATH environment variable!
2184
2185- Python bytecode files (*.pyc and *.pyo) are not compatible between
2186releases.
2187
2188
2189Overview of Changes Since 1.6
2190-----------------------------
2191
2192There are many new modules (including brand new XML support through
2193the xml package, and i18n support through the gettext module); a list
2194of all new modules is included below. Lots of bugs have been fixed.
2195
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002196The process for making major new changes to the language has changed
2197since Python 1.6. Enhancements must now be documented by a Python
2198Enhancement Proposal (PEP) before they can be accepted.
2199
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002200There are several important syntax enhancements, described in more
2201detail below:
2202
2203 - Augmented assignment, e.g. x += 1
2204
2205 - List comprehensions, e.g. [x**2 for x in range(10)]
2206
2207 - Extended import statement, e.g. import Module as Name
2208
2209 - Extended print statement, e.g. print >> file, "Hello"
2210
2211Other important changes:
2212
2213 - Optional collection of cyclical garbage
2214
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002215Python Enhancement Proposal (PEP)
2216---------------------------------
2217
2218PEP stands for Python Enhancement Proposal. A PEP is a design
2219document providing information to the Python community, or describing
2220a new feature for Python. The PEP should provide a concise technical
2221specification of the feature and a rationale for the feature.
2222
2223We intend PEPs to be the primary mechanisms for proposing new
2224features, for collecting community input on an issue, and for
2225documenting the design decisions that have gone into Python. The PEP
2226author is responsible for building consensus within the community and
2227documenting dissenting opinions.
2228
2229The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002230
2231Augmented Assignment
2232--------------------
2233
2234This must have been the most-requested feature of the past years!
2235Eleven new assignment operators were added:
2236
Guido van Rossume905e952000-09-05 12:42:46 +00002237 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002238
2239For example,
2240
2241 A += B
2242
2243is similar to
2244
2245 A = A + B
2246
2247except that A is evaluated only once (relevant when A is something
2248like dict[index].attr).
2249
2250However, if A is a mutable object, A may be modified in place. Thus,
2251if A is a number or a string, A += B has the same effect as A = A+B
2252(except A is only evaluated once); but if a is a list, A += B has the
2253same effect as A.extend(B)!
2254
2255Classes and built-in object types can override the new operators in
2256order to implement the in-place behavior; the not-in-place behavior is
2257used automatically as a fallback when an object doesn't implement the
2258in-place behavior. For classes, the method name is derived from the
2259method name for the corresponding not-in-place operator by inserting
2260an 'i' in front of the name, e.g. __iadd__ implements in-place
2261__add__.
2262
2263Augmented assignment was implemented by Thomas Wouters.
2264
2265
2266List Comprehensions
2267-------------------
2268
2269This is a flexible new notation for lists whose elements are computed
2270from another list (or lists). The simplest form is:
2271
2272 [<expression> for <variable> in <sequence>]
2273
Guido van Rossum56db0952000-09-06 23:34:25 +00002274For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002275This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002276
2277You can also add a condition:
2278
2279 [<expression> for <variable> in <sequence> if <condition>]
2280
2281For example, [w for w in words if w == w.lower()] would yield the list
2282of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002283than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002284
2285You can also have nested for loops and more than one 'if' clause. For
2286example, here's a function that flattens a sequence of sequences::
2287
2288 def flatten(seq):
2289 return [x for subseq in seq for x in subseq]
2290
2291 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
2292
2293This prints
2294
2295 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
2296
2297List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002298Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002299
2300
2301Extended Import Statement
2302-------------------------
2303
2304Many people have asked for a way to import a module under a different
2305name. This can be accomplished like this:
2306
2307 import foo
2308 bar = foo
2309 del foo
2310
2311but this common idiom gets old quickly. A simple extension of the
2312import statement now allows this to be written as follows:
2313
2314 import foo as bar
2315
2316There's also a variant for 'from ... import':
2317
2318 from foo import bar as spam
2319
2320This also works with packages; e.g. you can write this:
2321
2322 import test.regrtest as regrtest
2323
2324Note that 'as' is not a new keyword -- it is recognized only in this
2325context (this is only possible because the syntax for the import
2326statement doesn't involve expressions).
2327
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002328Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002329
2330
2331Extended Print Statement
2332------------------------
2333
2334Easily the most controversial new feature, this extension to the print
2335statement adds an option to make the output go to a different file
2336than the default sys.stdout.
2337
2338For example, to write an error message to sys.stderr, you can now
2339write:
2340
2341 print >> sys.stderr, "Error: bad dog!"
2342
2343As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00002344evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002345
2346 print >> None, "Hello world"
2347
2348is equivalent to
2349
2350 print "Hello world"
2351
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002352Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002353
2354
2355Optional Collection of Cyclical Garbage
2356---------------------------------------
2357
2358Python is now equipped with a garbage collector that can hunt down
2359cyclical references between Python objects. It's no replacement for
2360reference counting; in fact, it depends on the reference counts being
2361correct, and decides that a set of objects belong to a cycle if all
2362their reference counts can be accounted for from their references to
2363each other. This devious scheme was first proposed by Eric Tiedemann,
2364and brought to implementation by Neil Schemenauer.
2365
2366There's a module "gc" that lets you control some parameters of the
2367garbage collection. There's also an option to the configure script
2368that lets you enable or disable the garbage collection. In 2.0b1,
2369it's on by default, so that we (hopefully) can collect decent user
2370experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00002371performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002372off by default in the final 2.0 release.
2373
2374
2375Smaller Changes
2376---------------
2377
2378A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
2379map(None, seq1, seq2, ...) when the sequences have the same length;
2380i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
2381the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002382zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002383
2384sys.version_info is a tuple (major, minor, micro, level, serial).
2385
2386Dictionaries have an odd new method, setdefault(key, default).
2387dict.setdefault(key, default) returns dict[key] if it exists; if not,
2388it sets dict[key] to default and returns that value. Thus:
2389
2390 dict.setdefault(key, []).append(item)
2391
2392does the same work as this common idiom:
2393
2394 if not dict.has_key(key):
2395 dict[key] = []
2396 dict[key].append(item)
2397
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002398There are two new variants of SyntaxError that are raised for
2399indentation-related errors: IndentationError and TabError.
2400
2401Changed \x to consume exactly two hex digits; see PEP 223. Added \U
2402escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002403
2404The limits on the size of expressions and file in Python source code
2405have been raised from 2**16 to 2**32. Previous versions of Python
2406were limited because the maximum argument size the Python VM accepted
2407was 2**16. This limited the size of object constructor expressions,
2408e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
2409limit was raised thanks to a patch by Charles Waldman that effectively
2410fixes the problem. It is now much more likely that you will be
2411limited by available memory than by an arbitrary limit in Python.
2412
2413The interpreter's maximum recursion depth can be modified by Python
2414programs using sys.getrecursionlimit and sys.setrecursionlimit. This
2415limit is the maximum number of recursive calls that can be made by
2416Python code. The limit exists to prevent infinite recursion from
2417overflowing the C stack and causing a core dump. The default value is
24181000. The maximum safe value for a particular platform can be found
2419by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002420
2421New Modules and Packages
2422------------------------
2423
2424atexit - for registering functions to be called when Python exits.
2425
2426imputil - Greg Stein's alternative API for writing custom import
2427hooks.
2428
2429pyexpat - an interface to the Expat XML parser, contributed by Paul
2430Prescod.
2431
2432xml - a new package with XML support code organized (so far) in three
2433subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
2434would fill a volume. There's a special feature whereby a
2435user-installed package named _xmlplus overrides the standard
2436xmlpackage; this is intended to give the XML SIG a hook to distribute
2437backwards-compatible updates to the standard xml package.
2438
2439webbrowser - a platform-independent API to launch a web browser.
2440
2441
Guido van Rossume905e952000-09-05 12:42:46 +00002442Changed Modules
2443---------------
2444
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002445array -- new methods for array objects: count, extend, index, pop, and
2446remove
2447
2448binascii -- new functions b2a_hex and a2b_hex that convert between
2449binary data and its hex representation
2450
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002451calendar -- Many new functions that support features including control
2452over which day of the week is the first day, returning strings instead
2453of printing them. Also new symbolic constants for days of week,
2454e.g. MONDAY, ..., SUNDAY.
2455
2456cgi -- FieldStorage objects have a getvalue method that works like a
2457dictionary's get method and returns the value attribute of the object.
2458
2459ConfigParser -- The parser object has new methods has_option,
2460remove_section, remove_option, set, and write. They allow the module
2461to be used for writing config files as well as reading them.
2462
2463ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00002464optionally support the RFC 959 REST command.
2465
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002466gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00002467
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002468httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
2469the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00002470
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002471locale -- implement getdefaultlocale for Win32 and Macintosh
2472
2473marshal -- no longer dumps core when marshaling deeply nested or
2474recursive data structures
2475
2476os -- new functions isatty, seteuid, setegid, setreuid, setregid
2477
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002478os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
2479support under Unix.
2480
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002481os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002482
2483os.path -- fix semantics of os.path.commonprefix
2484
2485smtplib -- support for sending very long messages
2486
2487socket -- new function getfqdn()
2488
2489readline -- new functions to read, write and truncate history files.
2490The readline section of the library reference manual contains an
2491example.
2492
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002493select -- add interface to poll system call
2494
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002495shutil -- new copyfileobj function
2496
2497SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
2498HTTP server.
2499
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002500Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002501
2502urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00002503e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002504
2505whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00002506
2507
2508Obsolete Modules
2509----------------
2510
2511None. However note that 1.6 made a whole slew of modules obsolete:
2512stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
2513poly, zmod, strop, util, whatsound.
2514
2515
2516Changed, New, Obsolete Tools
2517----------------------------
2518
Tim Peters8b092332000-09-05 20:15:25 +00002519None.
Guido van Rossume905e952000-09-05 12:42:46 +00002520
2521
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002522C-level Changes
2523---------------
2524
2525Several cleanup jobs were carried out throughout the source code.
2526
2527All C code was converted to ANSI C; we got rid of all uses of the
2528Py_PROTO() macro, which makes the header files a lot more readable.
2529
2530Most of the portability hacks were moved to a new header file,
2531pyport.h; several other new header files were added and some old
2532header files were removed, in an attempt to create a more rational set
2533of header files. (Few of these ever need to be included explicitly;
2534they are all included by Python.h.)
2535
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002536Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002537and Win64, especially for the new Intel Itanium processor. Mick also
2538added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00002539
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002540The C APIs to return an object's size have been update to consistently
2541use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
2542previous versions, the abstract interfaces used PyXXX_Length and the
2543concrete interfaces used PyXXX_Size. The old names,
2544e.g. PyObject_Length, are still available for backwards compatibility
2545at the API level, but are deprecated.
2546
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002547The PyOS_CheckStack function has been implemented on Windows by
2548Fredrik Lundh. It prevents Python from failing with a stack overflow
2549on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002550
2551The GC changes resulted in creation of two new slots on object,
2552tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00002553the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002554
2555The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00002556C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002557
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002558PyErr_Format has been updated to automatically calculate the size of
2559the buffer needed to hold the formatted result string. This change
2560prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00002561
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002562New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00002563
Jeremy Hylton24c3d602000-09-05 19:36:26 +00002564PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
2565that are the same as their non-Ex counterparts except they take an
2566extra flag argument that tells them to close the file when done.
2567
2568XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002569
Tim Peters8b092332000-09-05 20:15:25 +00002570
2571Windows Changes
2572---------------
2573
2574New popen2/popen3/peopen4 in os module (see Changed Modules above).
2575
2576os.popen is much more usable on Windows 95 and 98. See Microsoft
2577Knowledge Base article Q150956. The Win9x workaround described there
2578is implemented by the new w9xpopen.exe helper in the root of your
2579Python installation. Note that Python uses this internally; it is not
2580a standalone program.
2581
2582Administrator privileges are no longer required to install Python
2583on Windows NT or Windows 2000. If you have administrator privileges,
2584Python's registry info will be written under HKEY_LOCAL_MACHINE.
2585Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00002586under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00002587uses of Python, but will prevent some advanced uses from working
2588(for example, running a Python script as an NT service, or possibly
2589from CGI).
2590
2591[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
2592installer; instead, it installs the needed Tcl/Tk files directly in the
2593Python directory. If you already have a Tcl/Tk installation, this
2594wastes some disk space (about 4 Megs) but avoids problems with
2595conflicting Tcl/Tk installations, and makes it much easier for Python
2596to ensure that Tcl/Tk can find all its files.
2597
2598[This was new in 1.6] The Windows installer now installs by default in
2599\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
2600
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00002601
2602Updates to the changes between 1.5.2 and 1.6
2603--------------------------------------------
2604
2605The 1.6 NEWS file can't be changed after the release is done, so here
2606is some late-breaking news:
2607
2608New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
2609and changes to getlocale() and setlocale().
2610
2611The new module is now enabled per default.
2612
2613It is not true that the encodings codecs cannot be used for normal
2614strings: the string.encode() (which is also present on 8-bit strings
2615!) allows using them for 8-bit strings too, e.g. to convert files from
2616cp1252 (Windows) to latin-1 or vice-versa.
2617
2618Japanese codecs are available from Tamito KAJIYAMA:
2619http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
2620
2621
Guido van Rossumab9d6f01998-08-10 22:01:13 +00002622======================================================================