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Guido van Rossum5b08f132001-04-16 02:05:23 +00001What's New in Python 2.1c2?
2===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +00003
Guido van Rossum5b08f132001-04-16 02:05:23 +00004A flurry of small changes, and one showstopper fixed in the nick of
5time made it necessary to release another release candidate. The list
6here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +00007
Guido van Rossum5b08f132001-04-16 02:05:23 +00008Core
Guido van Rossum4fb60362001-04-13 00:46:14 +00009
Guido van Rossum5b08f132001-04-16 02:05:23 +000010- Tim discovered a nasty bug in the dictionary code, caused by
11 PyDict_Next() calling dict_resize(), and the GC code's use of
12 PyDict_Next() violating an assumption in dict_items(). This was
13 fixed with considerable amounts of band-aid, but the net effect is a
14 saner and more robust implementation.
15
16- Made a bunch of symbols static that were accidentally global.
17
18Build and Ports
19
20- The setup.py script didn't check for a new enough version of zlib
21 (1.1.3 is needed). Now it does.
22
23- Changed "make clean" target to also remove shared libraries.
24
25- Added a more general warning about the SGI Irix optimizer to README.
26
27Library
28
29- Fix a bug in urllib.basejoin("http://host", "../file.html") which
30 omitted the slash between host and file.html.
31
32- The mailbox module's _Mailbox class contained a completely broken
33 and undocumented seek() method. Ripped it out.
34
35- Fixed a bunch of typos in various library modules (urllib2, smtpd,
36 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
37
38- Fixed a few last-minute bugs in unittest.
39
40Extensions
41
42- Reverted the patch to the OpenSSL code in socketmodule.c to support
43 RAND_status() and the EGD, and the subsequent patch that tried to
44 fix it for pre-0.9.5 versions; the problem with the patch is that on
45 some systems it issues a warning whenever socket is imported, and
46 that's unacceptable.
47
48Tests
49
50- Fixed the pickle tests to work with "import test.test_pickle".
51
52- Tweaked test_locale.py to actually run the test Windows.
53
54- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
55 not "wb" (which is not a valid mode at all).
56
57- Fix pstats browser crashes. Import readline if it exists to make
58 the user interface nicer.
59
60- Add "import thread" to the top of test modules that import the
61 threading module (test_asynchat and test_threadedtempfile). This
62 prevents test failures caused by a broken threading module resulting
63 from a previously caught failed import.
64
65- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
66 needed on some platforms (e.g. Solaris 8) when the tests are run
67 twice in succession.
68
69- Skip rather than fail test_sunaudiodev if no audio device is found.
70
71
72What's New in Python 2.1c1?
73===========================
74
75This list was significantly updated when 2.1c2 was released; the 2.1c1
76release didn't mention most changes that were actually part of 2.1c1:
77
78Legal
79
80- Copyright was assigned to the Python Software Foundation (PSF) and a
81 PSF license (very similar to the CNRI license) was added.
82
83- The CNRI copyright notice was updated to include 2001.
84
85Core
Barry Warsaw11e89c72001-04-11 20:37:57 +000086
Guido van Rossumc9932722001-04-12 02:31:27 +000087- After a public outcry, assignment to __debug__ is no longer illegal;
88 instead, a warning is issued. It will become illegal in 2.2.
89
Guido van Rossum5b08f132001-04-16 02:05:23 +000090- Fixed a core dump with "%#x" % 0, and changed the semantics so that
91 "%#x" now always prepends "0x", even if the value is zero.
92
93- Fixed some nits in the bytecode compiler.
94
95- Fixed core dumps when calling certain kinds of non-functions.
96
97- Fixed various core dumps caused by reference count bugs.
98
99Build and Ports
100
101- Use INSTALL_SCRIPT to install script files.
102
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000103- New port: SCO Unixware 7, by Billy G. Allie.
104
Guido van Rossum5b08f132001-04-16 02:05:23 +0000105- Updated RISCOS port.
106
107- Updated BeOS port and notes.
108
109- Various other porting problems resolved.
110
111Library
112
113- The TERMIOS and SOCKET modules are now truly obsolete and
114 unnecessary. Their symbols are incorporated in the termios and
115 socket modules.
116
117- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
118 better tests for pickling.
119
120- threading: make Condition.wait() robust against KeyboardInterrupt.
121
122- zipfile: add support to zipfile to support opening an archive
123 represented by an open file rather than a file name. Fix bug where
124 the archive was not properly closed. Fixed a bug in this bugfix
125 where flush() was called for a read-only file.
126
127- imputil: added an uninstall() method to the ImportManager.
128
129- Canvas: fixed bugs in lower() and tkraise() methods.
130
131- SocketServer: API change (added overridable close_request() method)
132 so that the TCP server can explicitly close the request.
133
134- pstats: Eric Raymond added a simple interactive statistics browser,
135 invoked when the module is run as a script.
136
137- locale: fixed a problem in format().
138
139- webbrowser: made it work when the BROWSER environment variable has a
140 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
141 KDE 2. Fixed some other nits.
142
143- unittest: changes to allow using a different exception than
144 AssertionError, and added a few more function aliases. Some other
145 small changes.
146
147- urllib, urllib2: fixed redirect problems and a coupleof other nits.
148
149- asynchat: fixed a critical bug in asynchat that slipped through the
150 2.1b2 release. Fixed another rare bug.
151
152- Fix some unqualified except: clauses (always a bad code example).
153
154XML
155
156- pyexpat: new API get_version_string().
157
158- Fixed some minidom bugs.
159
160Extensions
161
162- Fixed a core dump in _weakref. Removed the weakref.mapping()
163 function (it adds nothing to the API).
164
165- Rationalized the use of header files in the readline module, to make
166 it compile (albeit with some warnings) with the very recent readline
167 4.2, without breaking for earlier versions.
168
169- Hopefully fixed a buffering problem in linuxaudiodev.
170
171- Attempted a fix to make the OpenSSL support in the socket module
172 work again with pre-0.9.5 versions of OpenSSL.
173
174Tests
175
176- Added a test case for asynchat and asyncore.
177
178- Removed coupling between tests where one test failing could break
179 another.
180
181Tools
182
183- Ping added an interactive help browser to pydoc, fixed some nits
184 in the rest of the pydoc code, and added some features to his
185 inspect module.
186
187- An updated python-mode.el version 4.1 which integrates Ken
188 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
189 much nicer in XEmacs and Emacs. When stepping through your program
190 with pdb, in either the shell window or the *Python* window, the
191 source file and line will be tracked by an arrow. Very cool!
192
193- IDLE: syntax warnings in interactive mode are changed into errors.
194
195- Some improvements to Tools/webchecker (ignore some more URL types,
196 follow some more links).
197
198- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000199
Barry Warsaw11e89c72001-04-11 20:37:57 +0000200
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000201What's New in Python 2.1 beta 2?
202================================
203
Guido van Rossum053ae352001-03-22 14:17:21 +0000204(Unlisted are many fixed bugs, more documentation, etc.)
205
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000206Core language, builtins, and interpreter
207
Guido van Rossum053ae352001-03-22 14:17:21 +0000208- The nested scopes work (enabled by "from __future__ import
209 nested_scopes") is completed; in particular, the future now extends
210 into code executed through exec, eval() and execfile(), and into the
211 interactive interpreter.
212
213- When calling a base class method (e.g. BaseClass.__init__(self)),
214 this is now allowed even if self is not strictly spoken a class
215 instance (e.g. when using metaclasses or the Don Beaudry hook).
216
217- Slice objects are now comparable but not hashable; this prevents
218 dict[:] from being accepted but meaningless.
219
220- Complex division is now calculated using less braindead algorithms.
221 This doesn't change semantics except it's more likely to give useful
222 results in extreme cases. Complex repr() now uses full precision
223 like float repr().
224
225- sgmllib.py now calls handle_decl() for simple <!...> declarations.
226
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000227- It is illegal to assign to the name __debug__, which is set when the
228 interpreter starts. It is effectively a compile-time constant.
229
230- A warning will be issued if a global statement for a variable
231 follows a use or assignment of that variable.
232
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000233Standard library
234
Guido van Rossum053ae352001-03-22 14:17:21 +0000235- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
236 inspired by JUnit), is now part of the standard library. You now
237 have a choice of two testing frameworks: unittest requires you to
238 write testcases as separate code, doctest gathers them from
239 docstrings. Both approaches have their advantages and
240 disadvantages.
241
242- A new module Tix was added, which wraps the Tix extension library
243 for Tk. With that module, it is not necessary to statically link
244 Tix with _tkinter, since Tix will be loaded with Tcl's "package
245 require" command. See Demo/tix/.
246
247- tzparse.py is now obsolete.
248
249- In gzip.py, the seek() and tell() methods are removed -- they were
250 non-functional anyway, and it's better if callers can test for their
251 existence with hasattr().
252
253Python/C API
254
255- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
256 that's already in the dictionary during a PyDict_Next() iteration.
257 This used to fail occasionally when a dictionary resize operation
258 could be triggered that would rehash all the keys. All other
259 modifications to the dictionary are still off-limits during a
260 PyDict_Next() iteration!
261
262- New extended APIs related to passing compiler variables around.
263
264- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
265 implement isinstance() and issubclass().
266
267- Py_BuildValue() now has a "D" conversion to create a Python complex
268 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000269
Fred Drake4e262a92001-03-22 18:26:47 +0000270- Extensions types which support weak references must now set the
271 field allocated for the weak reference machinery to NULL themselves;
272 this is done to avoid the cost of checking each object for having a
273 weakly referencable type in PyObject_INIT(), since most types are
274 not weakly referencable.
275
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000276- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
277 free variables and cell variables to and from the frame's f_locals.
278
279- Variants of several functions defined in pythonrun.h have been added
280 to support the nested_scopes future statement. The variants all end
281 in Flags and take an extra argument, a PyCompilerFlags *; examples:
282 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
283 variants may be removed in Python 2.2, when nested scopes are
284 mandatory.
285
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000286Distutils
287
288- the sdist command now writes a PKG-INFO file, as described in PEP 241,
289 into the release tree.
290
291- several enhancements to the bdist_wininst command from Thomas Heller
292 (an uninstaller, more customization of the installer's display)
293
294- from Jack Jansen: added Mac-specific code to generate a dialog for
295 users to specify the command-line (because providing a command-line with
296 MacPython is awkward). Jack also made various fixes for the Mac
297 and the Metrowerks compiler.
298
299- added 'platforms' and 'keywords' to the set of metadata that can be
Andrew M. Kuchling68ad64a2001-03-31 02:42:42 +0000300 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000301
302- applied patches from Jason Tishler to make the compiler class work with
303 Cygwin.
304
305
Tim Peters2fe289a2001-03-01 22:19:38 +0000306What's New in Python 2.1 beta 1?
307================================
Tim Petersd66595f2001-02-04 03:09:53 +0000308
309Core language, builtins, and interpreter
310
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000311- Following an outcry from the community about the amount of code
312 broken by the nested scopes feature introduced in 2.1a2, we decided
313 to make this feature optional, and to wait until Python 2.2 (or at
314 least 6 months) to make it standard. The option can be enabled on a
315 per-module basis by adding "from __future__ import nested_scopes" at
316 the beginning of a module (before any other statements, but after
317 comments and an optional docstring). See PEP 236 (Back to the
318 __future__) for a description of the __future__ statement. PEP 227
319 (Statically Nested Scopes) has been updated to reflect this change,
320 and to clarify the semantics in a number of endcases.
321
322- The nested scopes code, when enabled, has been hardened, and most
323 bugs and memory leaks in it have been fixed.
324
325- Compile-time warnings are now generated for a number of conditions
326 that will break or change in meaning when nested scopes are enabled:
327
328 - Using "from...import *" or "exec" without in-clause in a function
329 scope that also defines a lambda or nested function with one or
330 more free (non-local) variables. The presence of the import* or
331 bare exec makes it impossible for the compiler to determine the
332 exact set of local variables in the outer scope, which makes it
333 impossible to determine the bindings for free variables in the
334 inner scope. To avoid the warning about import *, change it into
335 an import of explicitly name object, or move the import* statement
336 to the global scope; to avoid the warning about bare exec, use
337 exec...in... (a good idea anyway -- there's a possibility that
338 bare exec will be deprecated in the future).
339
340 - Use of a global variable in a nested scope with the same name as a
341 local variable in a surrounding scope. This will change in
342 meaning with nested scopes: the name in the inner scope will
343 reference the variable in the outer scope rather than the global
344 of the same name. To avoid the warning, either rename the outer
345 variable, or use a global statement in the inner function.
346
Neil Schemenauera35c6882001-02-27 04:45:05 +0000347- An optional object allocator has been included. This allocator is
348 optimized for Python objects and should be faster and use less memory
349 than the standard system allocator. It is not enabled by default
350 because of possible thread safety problems. The allocator is only
351 protected by the Python interpreter lock and it is possible that some
352 extension modules require a thread safe allocator. The object
353 allocator can be enabled by providing the "--with-pymalloc" option to
354 configure.
355
Tim Petersd66595f2001-02-04 03:09:53 +0000356Standard library
357
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000358- pyexpat now detects the expat version if expat.h defines it. A
359 number of additional handlers are provided, which are only available
360 since expat 1.95. In addition, the methods SetParamEntityParsing and
361 GetInputContext of Parser objects are available with 1.95.x
362 only. Parser objects now provide the ordered_attributes and
363 specified_attributes attributes. A new module expat.model was added,
364 which offers a number of additional constants if 1.95.x is used.
365
366- xml.dom offers the new functions registerDOMImplementation and
367 getDOMImplementation.
368
369- xml.dom.minidom offers a toprettyxml method. A number of DOM
370 conformance issues have been resolved. In particular, Element now
371 has an hasAttributes method, and the handling of namespaces was
372 improved.
373
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000374- Ka-Ping Yee contributed two new modules: inspect.py, a module for
375 getting information about live Python code, and pydoc.py, a module
376 for interactively converting docstrings to HTML or text.
377 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000378 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000379 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
380 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000381
Tim Peters1eff7962001-03-01 02:31:33 +0000382- New library module difflib.py, primarily packaging the SequenceMatcher
383 class at the heart of the popular ndiff.py file-comparison tool.
384
385- doctest.py (a framework for verifying Python code examples in docstrings)
386 is now part of the std library.
387
Tim Petersd66595f2001-02-04 03:09:53 +0000388Windows changes
389
Guido van Rossume3955a82001-03-02 14:05:59 +0000390- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
391 small GUI that lets you browse the module docstrings using your
392 default web browser.
393
Tim Peters1eff7962001-03-01 02:31:33 +0000394- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
395 Platforms) is implemented. See
396
397 http://python.sourceforge.net/peps/pep-0235.html
398
399 for full details, especially the "Current Lower-Left Semantics" section.
400 The new Windows import rules are simpler than before:
401
402 A. If the PYTHONCASEOK environment variable exists, same as
403 before: silently accept the first case-insensitive match of any
404 kind; raise ImportError if none found.
405
406 B. Else search sys.path for the first case-sensitive match; raise
407 ImportError if none found.
408
409 The same rules have been implented on other platforms with case-
410 insensitive but case-preserving filesystems too (including Cygwin, and
411 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000412
Tim Peters25a9ce32001-02-19 07:06:36 +0000413- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
414 what it's supposed to do (and does do under NT and 2000) via direct
415 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000416 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000417 all Win9x systems before.
418
Tim Peters1eff7962001-03-01 02:31:33 +0000419- Build: Subproject _test (effectively) renamed to _testcapi.
420
Tim Peters2fe289a2001-03-01 22:19:38 +0000421New platforms
422
423- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
424 Thanks to Steven Majewski!
425
426- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
427 Tishler!
428
Guido van Rossum9089b272001-03-02 06:49:50 +0000429- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
430 Schwertberger! See RISCOS/README for more information -- it seems
431 that because of the bizarre filename conventions on RISCOS, no port
432 to that platform is easy. Note that the new variable os.endsep is
433 silently supported in order to make life easier on this platform,
434 but we don't advertise it because it's not worth for most folks to
435 care about RISCOS portability.
436
Tim Peters25a9ce32001-02-19 07:06:36 +0000437
Tim Petersd7b5e882001-01-25 03:36:26 +0000438What's New in Python 2.1 alpha 2?
439=================================
Tim Peters40ead762001-01-27 05:35:26 +0000440
Tim Petersd7b5e882001-01-25 03:36:26 +0000441Core language, builtins, and interpreter
442
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000443- Scopes nest. If a name is used in a function or class, but is not
444 local, the definition in the nearest enclosing function scope will
445 be used. One consequence of this change is that lambda statements
446 could reference variables in the namespaces where the lambda is
447 defined. In some unusual cases, this change will break code.
448
449 In all previous version of Python, names were resolved in exactly
450 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000451 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000452 function A is defined within a function B, the names bound in B are
453 not visible in A. The new rules make names bound in B visible in A,
454 unless A contains a name binding that hides the binding in B.
455
456 Section 4.1 of the reference manual describes the new scoping rules
457 in detail. The test script in Lib/test/test_scope.py demonstrates
458 some of the effects of the change.
459
460 The new rules will cause existing code to break if it defines nested
461 functions where an outer function has local variables with the same
462 name as globals or builtins used by the inner function. Example:
463
464 def munge(str):
465 def helper(x):
466 return str(x)
467 if type(str) != type(''):
468 str = helper(str)
469 return str.strip()
470
471 Under the old rules, the name str in helper() is bound to the
472 builtin function str(). Under the new rules, it will be bound to
473 the argument named str and an error will occur when helper() is
474 called.
475
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000476- The compiler will report a SyntaxError if "from ... import *" occurs
477 in a function or class scope. The language reference has documented
478 that this case is illegal, but the compiler never checked for it.
479 The recent introduction of nested scope makes the meaning of this
480 form of name binding ambiguous. In a future release, the compiler
481 may allow this form when there is no possibility of ambiguity.
482
Tim Peters40ead762001-01-27 05:35:26 +0000483- repr(string) is easier to read, now using hex escapes instead of octal,
484 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
485
486 >>> "\texample \r\n" + chr(0) + chr(255)
487 '\texample \r\n\x00\xff' # in 2.1
488 '\011example \015\012\000\377' # in 2.0
489
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000490- Functions are now compared and hashed by identity, not by value, since
491 the func_code attribute is writable.
492
Fred Drakefb9d7122001-02-01 20:00:40 +0000493- Weak references (PEP 205) have been added. This involves a few
494 changes in the core, an extension module (_weakref), and a Python
495 module (weakref). The weakref module is the public interface. It
496 includes support for "explicit" weak references, proxy objects, and
497 mappings with weakly held values.
498
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000499- A 'continue' statement can now appear in a try block within the body
500 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000501 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000502
Tim Petersd7b5e882001-01-25 03:36:26 +0000503Standard library
504
Barry Warsaw30dbd142001-01-31 22:14:01 +0000505- mailbox.py now has a new class, PortableUnixMailbox which is
506 identical to UnixMailbox but uses a more portable scheme for
507 determining From_ separators. Also, the constructors for all the
508 classes in this module have a new optional `factory' argument, which
509 is a callable used when new message classes must be instantiated by
510 the next() method.
511
Tim Petersd7b5e882001-01-25 03:36:26 +0000512- random.py is now self-contained, and offers all the functionality of
513 the now-deprecated whrandom.py. See the docs for details. random.py
514 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000515 and restoring the internal state of the generator; and jumpahead(n),
516 for quickly forcing the internal state to be the same as if n calls to
517 random() had been made. The latter is particularly useful for multi-
518 threaded programs, creating one instance of the random.Random() class for
519 each thread, then using .jumpahead() to force each instance to use a
520 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000521
Tim Peters0de88fc2001-02-01 04:59:18 +0000522- random.py's seed() function is new. For bit-for-bit compatibility with
523 prior releases, use the whseed function instead. The new seed function
524 addresses two problems: (1) The old function couldn't produce more than
525 about 2**24 distinct internal states; the new one about 2**45 (the best
526 that can be done in the Wichmann-Hill generator). (2) The old function
527 sometimes produced identical internal states when passed distinct
528 integers, and there was no simple way to predict when that would happen;
529 the new one guarantees to produce distinct internal states for all
530 arguments in [0, 27814431486576L).
531
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000532- The socket module now supports raw packets on Linux. The socket
533 family is AF_PACKET.
534
Tim Peters9ea17ac2001-02-02 05:57:15 +0000535- test_capi.py is a start at running tests of the Python C API. The tests
536 are implemented by the new Modules/_testmodule.c.
537
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000538- A new extension module, _symtable, provides provisional access to the
539 internal symbol table used by the Python compiler. A higher-level
540 interface will be added on top of _symtable in a future release.
541
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000542- Removed the obsolete soundex module.
543
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000544- xml.dom.minidom now uses the standard DOM exceptions. Node supports
545 the isSameNode method; NamedNodeMap the get method.
546
547- xml.sax.expatreader supports the lexical handler property; it
548 generates comment, startCDATA, and endCDATA events.
549
Tim Petersee826f82001-01-31 19:39:44 +0000550Windows changes
551
552- Build procedure: the zlib project is built in a different way that
553 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000554 the zlib binary used. See PCbuild\readme.txt for details. Your old
555 zlib-related directories can be deleted; you'll need to download fresh
556 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000557
Tim Peters9ea17ac2001-02-02 05:57:15 +0000558- Build: New subproject _test for the benefit of test_capi.py (see above).
559
Tim Petersb16c56f2001-02-02 21:24:51 +0000560- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
561 interface to some Python compiler internals).
562
563- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000564 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000565
Tim Petersa3a3a032000-11-30 05:22:44 +0000566What's New in Python 2.1 alpha 1?
567=================================
568
569Core language, builtins, and interpreter
570
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000571- There is a new Unicode companion to the PyObject_Str() API
572 called PyObject_Unicode(). It behaves in the same way as the
573 former, but assures that the returned value is an Unicode object
574 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000575
Guido van Rossumf98eda02001-01-17 15:54:45 +0000576- The comparison operators support "rich comparison overloading" (PEP
577 207). C extension types can provide a rich comparison function in
578 the new tp_richcompare slot in the type object. The cmp() function
579 and the C function PyObject_Compare() first try the new rich
580 comparison operators before trying the old 3-way comparison. There
581 is also a new C API PyObject_RichCompare() (which also falls back on
582 the old 3-way comparison, but does not constrain the outcome of the
583 rich comparison to a Boolean result).
584
585 The rich comparison function takes two objects (at least one of
586 which is guaranteed to have the type that provided the function) and
587 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
588 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
589 object, which may be NotImplemented (in which case the tp_compare
590 slot function is used as a fallback, if defined).
591
592 Classes can overload individual comparison operators by defining one
593 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000594 __ge__. There are no explicit "reflected argument" versions of
595 these; instead, __lt__ and __gt__ are each other's reflection,
596 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
597 reflection (similar at the C level). No other implications are
598 made; in particular, Python does not assume that == is the Boolean
599 inverse of !=, or that < is the Boolean inverse of >=. This makes
600 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000601
602 Classes or types that want to implement (in)equality tests but not
603 the ordering operators (i.e. unordered types) should implement ==
604 and !=, and raise an error for the ordering operators.
605
Guido van Rossuma88479f2001-01-18 14:28:08 +0000606 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +0000607 Boolean; e.g. a matrix type might want to return a matrix of bits
608 for A < B, giving elementwise comparisons. Such types should ensure
609 that any interpretation of their value in a Boolean context raises
610 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
611 at the C level) to always raise an exception.
612
Guido van Rossuma88479f2001-01-18 14:28:08 +0000613- Complex numbers use rich comparisons to define == and != but raise
614 an exception for <, <=, > and >=. Unfortunately, this also means
615 that cmp() of two complex numbers raises an exception when the two
616 numbers differ. Since it is not mathematically meaningful to compare
617 complex numbers except for equality, I hope that this doesn't break
618 too much code.
619
Tim Peters3389f192001-02-18 08:48:49 +0000620- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +0000621 not defined by the language, other than that it's arbitrary but
622 consistent (see the Reference Manual). An implementation detail changed
623 in 2.1a1 such that None now compares less than any other object. Code
624 relying on this new behavior (like code that relied on the previous
625 behavior) does so at its own risk.
626
Barry Warsaw573b5412001-01-15 20:43:18 +0000627- Functions and methods now support getting and setting arbitrarily
628 named attributes (PEP 232). Functions have a new __dict__
629 (a.k.a. func_dict) which hold the function attributes. Methods get
630 and set attributes on their underlying im_func. It is a TypeError
631 to set an attribute on a bound method.
632
Guido van Rossum051e3352001-01-15 19:11:10 +0000633- The xrange() object implementation has been improved so that
634 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
635 limitation that in this case len(xrange(sys.maxint)) can't be
636 calculated, but the common idiom "for i in xrange(sys.maxint)" will
637 work fine as long as the index i doesn't actually reach 2**31.
638 (Python uses regular ints for sequence and string indices; fixing
639 that is much more work.)
640
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000641- Two changes to from...import:
642
Guido van Rossumba381232001-02-03 15:06:40 +0000643 1) "from M import X" now works even if (after loading module M)
644 sys.modules['M'] is not a real module; it's basically a getattr()
645 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000646
647 2) "from M import *" now looks for M.__all__ to decide which names to
648 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
649 filters out names starting with '_' as before. Whether or not
650 __all__ exists, there's no restriction on the type of M.
651
Guido van Rossumf61f1662001-01-10 20:13:55 +0000652- File objects have a new method, xreadlines(). This is the fastest
653 way to iterate over all lines in a file:
654
655 for line in file.xreadlines():
656 ...do something to line...
657
658 See the xreadlines module (mentioned below) for how to do this for
659 other file-like objects.
660
661- Even if you don't use file.xreadlines(), you may expect a speedup on
662 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +0000663 quite a bit in platform-specific ways: on systems (like Linux) that
664 support flockfile(), getc_unlocked(), and funlockfile(), those are
665 used by default. On systems (like Windows) without getc_unlocked(),
666 a complicated (but still thread-safe) method using fgets() is used by
667 default.
668
Tim Petersd52269b2001-01-25 06:23:18 +0000669 You can force use of the fgets() method by #define'ing
670 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +0000671 getc_unlocked()).
672
Tim Petersd52269b2001-01-25 06:23:18 +0000673 You can force fgets() not to be used by #define'ing
674 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +0000675 test_bufio.py fails -- and let us know if it does!).
676
677- In addition, the fileinput module, while still slower than the other
678 methods on most platforms, has been sped up too, by using
679 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000680
681- Support for run-time warnings has been added, including a new
682 command line option (-W) to specify the disposition of warnings.
683 See the description of the warnings module below.
684
685- Extensive changes have been made to the coercion code. This mostly
686 affects extension modules (which can now implement mixed-type
687 numerical operators without having to use coercion), but
688 occasionally, in boundary cases the coercion semantics have changed
689 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000690 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000691 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000692 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000693
Guido van Rossumf98eda02001-01-17 15:54:45 +0000694- In connection with the coercion changes, a new built-in singleton
695 object, NotImplemented is defined. This can be returned for
696 operations that wish to indicate they are not implemented for a
697 particular combination of arguments. From C, this is
698 Py_NotImplemented.
699
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000700- The interpreter accepts now bytecode files on the command line even
701 if they do not have a .pyc or .pyo extension. On Linux, after executing
702
Martin v. Löwise214baa2001-02-04 22:37:56 +0000703import imp,sys,string
704magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
705reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
706open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000707
708 any byte code file can be used as an executable (i.e. as an argument
709 to execve(2)).
710
Tim Peters9940b802000-12-01 07:59:35 +0000711- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000712 character. In 1.6 and earlier, they never produced a sign,
713 and raised an error if the value of the long was too large
714 to fit in a Python int. In 2.0, they produced a sign if and
715 only if too large to fit in an int. This was inconsistent
716 across platforms (because the size of an int varies across
717 platforms), and inconsistent with hex() and oct(). Example:
718
719 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000720 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000721 'ffffffbe' # in 2.0 and before, on 32-bit machines
722 >>> hex(-0x42L)
723 '-0x42L' # in all versions of Python
724
Tim Peters9940b802000-12-01 07:59:35 +0000725 The behavior of %d formats for negative Python longs remains
726 the same as in 2.0 (although in 1.6 and before, they raised
727 an error if the long didn't fit in a Python int).
728
729 %u formats don't make sense for Python longs, but are allowed
730 and treated the same as %d in 2.1. In 2.0, a negative long
731 formatted via %u produced a sign if and only if too large to
732 fit in an int. In 1.6 and earlier, a negative long formatted
733 via %u raised an error if it was too big to fit in an int.
734
Guido van Rossum3661d392000-12-12 22:10:31 +0000735- Dictionary objects have an odd new method, popitem(). This removes
736 an arbitrary item from the dictionary and returns it (in the form of
737 a (key, value) pair). This can be useful for algorithms that use a
738 dictionary as a bag of "to do" items and repeatedly need to pick one
739 item. Such algorithms normally end up running in quadratic time;
740 using popitem() they can usually be made to run in linear time.
741
Tim Peters36cdad12000-12-29 02:06:45 +0000742Standard library
743
Thomas Woutersfe385252001-01-19 23:16:56 +0000744- In the time module, the time argument to the functions strftime,
745 localtime, gmtime, asctime and ctime is now optional, defaulting to
746 the current time (in the local timezone).
747
Guido van Rossumda91f222001-01-15 16:36:08 +0000748- The ftplib module now defaults to passive mode, which is deemed a
749 more useful default given that clients are often inside firewalls
750 these days. Note that this could break if ftplib is used to connect
751 to a *server* that is inside a firewall, from outside; this is
752 expected to be a very rare situation. To fix that, you can call
753 ftp.set_pasv(0).
754
Martin v. Löwis10a27872001-01-13 09:54:41 +0000755- The module site now treats .pth files not only for path configuration,
756 but also supports extensions to the initialization code: Lines starting
757 with import are executed.
758
Guido van Rossumf61f1662001-01-10 20:13:55 +0000759- There's a new module, warnings, which implements a mechanism for
760 issuing and filtering warnings. There are some new built-in
761 exceptions that serve as warning categories, and a new command line
762 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
763 turns warnings into errors). warnings.warn(message[, category])
764 issues a warning message; this can also be called from C as
765 PyErr_Warn(category, message).
766
767- A new module xreadlines was added. This exports a single factory
768 function, xreadlines(). The intention is that this code is the
769 absolutely fastest way to iterate over all lines in an open
770 file(-like) object:
771
772 import xreadlines
773 for line in xreadlines.xreadlines(file):
774 ...do something to line...
775
776 This is equivalent to the previous the speed record holder using
777 file.readlines(sizehint). Note that if file is a real file object
778 (as opposed to a file-like object), this is equivalent:
779
780 for line in file.xreadlines():
781 ...do something to line...
782
Tim Peters36cdad12000-12-29 02:06:45 +0000783- The bisect module has new functions bisect_left, insort_left,
784 bisect_right and insort_right. The old names bisect and insort
785 are now aliases for bisect_right and insort_right. XXX_right
786 and XXX_left methods differ in what happens when the new element
787 compares equal to one or more elements already in the list: the
788 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000789 right. Code that doesn't care where equal elements end up should
790 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000791
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000792- The new curses.panel module wraps the panel library that forms part
793 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
794
Guido van Rossumf61f1662001-01-10 20:13:55 +0000795- The SocketServer module now sets the allow_reuse_address flag by
796 default in the TCPServer class.
797
798- A new function, sys._getframe(), returns the stack frame pointer of
799 the caller. This is intended only as a building block for
800 higher-level mechanisms such as string interpolation.
801
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000802- The pyexpat module supports a number of new handlers, which are
803 available only in expat 1.2. If invocation of a callback fails, it
804 will report an additional frame in the traceback. Parser objects
805 participate now in garbage collection. If expat reports an unknown
806 encoding, pyexpat will try to use a Python codec; that works only
807 for single-byte charsets. The parser type objects is exposed as
808 XMLParserObject.
809
810- xml.dom now offers standard definitions for symbolic node type and
811 exception code constants, and a hierarchy of DOM exceptions. minidom
812 was adjusted to use them.
813
814- The conformance of xml.dom.minidom to the DOM specification was
815 improved. It detects a number of additional error cases; the
816 previous/next relationship works even when the tree is modified;
817 Node supports the normalize() method; NamedNodeMap, DocumentType and
818 DOMImplementation classes were added; Element supports the
819 hasAttribute and hasAttributeNS methods; and Text supports the splitText
820 method.
821
Guido van Rossumf61f1662001-01-10 20:13:55 +0000822Build issues
823
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000824- For Unix (and Unix-compatible) builds, configuration and building of
825 extension modules is now greatly automated. Rather than having to
826 edit the Modules/Setup file to indicate which modules should be
827 built and where their include files and libraries are, a
828 distutils-based setup.py script now takes care of building most
829 extension modules. All extension modules built this way are built
830 as shared libraries. Only a few modules that must be linked
831 statically are still listed in the Setup file; you won't need to
832 edit their configuration.
833
834- Python should now build out of the box on Cygwin. If it doesn't,
835 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000836
837- Python now always uses its own (renamed) implementation of getopt()
838 -- there's too much variation among C library getopt()
839 implementations.
840
841- C++ compilers are better supported; the CXX macro is always set to a
842 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000843
Tim Petersd92dfe02000-12-12 01:18:41 +0000844Windows changes
845
846- select module: By default under Windows, a select() call
847 can specify no more than 64 sockets. Python now boosts
848 this Microsoft default to 512. If you need even more than
849 that, see the MS docs (you'll need to #define FD_SETSIZE
850 and recompile Python from source).
851
Guido van Rossumf61f1662001-01-10 20:13:55 +0000852- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
853 subdirectory is no more!
854
Tim Petersa3a3a032000-11-30 05:22:44 +0000855
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000856What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000857=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000858
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000859Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000860changes are in the file HISTORY. If you are making the jump directly
861from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
862HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000863
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000864Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
865the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
866http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000867
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000868--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000869
870======================================================================
871
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000872What's new in 2.0 (since release candidate 1)?
873==============================================
874
875Standard library
876
877- The copy_reg module was modified to clarify its intended use: to
878 register pickle support for extension types, not for classes.
879 pickle() will raise a TypeError if it is passed a class.
880
881- Fixed a bug in gettext's "normalize and expand" code that prevented
882 it from finding an existing .mo file.
883
884- Restored support for HTTP/0.9 servers in httplib.
885
Tim Peters989b7b92000-10-16 20:24:53 +0000886- The math module was changed to stop raising OverflowError in case of
887 underflow, and return 0 instead in underflow cases. Whether Python
888 used to raise OverflowError in case of underflow was platform-
889 dependent (it did when the platform math library set errno to ERANGE
890 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000891
892- Fixed a bug in StringIO that occurred when the file position was not
893 at the end of the file and write() was called with enough data to
894 extend past the end of the file.
895
896- Fixed a bug that caused Tkinter error messages to get lost on
897 Windows. The bug was fixed by replacing direct use of
898 interp->result with Tcl_GetStringResult(interp).
899
900- Fixed bug in urllib2 that caused it to fail when it received an HTTP
901 redirect response.
902
903- Several changes were made to distutils: Some debugging code was
904 removed from util. Fixed the installer used when an external zip
905 program (like WinZip) is not found; the source code for this
906 installer is in Misc/distutils. check_lib() was modified to behave
907 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
908 test for whether installed modules are on sys.path was changed to
909 use both normcase() and normpath().
910
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000911- Several minor bugs were fixed in the xml package (the minidom,
912 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000913
914- The regression test driver (regrtest.py) behavior when invoked with
915 -l changed: It now reports a count of objects that are recognized as
916 garbage but not freed by the garbage collector.
917
Tim Peters989b7b92000-10-16 20:24:53 +0000918- The regression test for the math module was changed to test
919 exceptional behavior when the test is run in verbose mode. Python
920 cannot yet guarantee consistent exception behavior across platforms,
921 so the exception part of test_math is run only in verbose mode, and
922 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000923
924Internals
925
926- PyOS_CheckStack() has been disabled on Win64, where it caused
927 test_sre to fail.
928
929Build issues
930
931- Changed compiler flags, so that gcc is always invoked with -Wall and
932 -Wstrict-prototypes. Users compiling Python with GCC should see
933 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000934 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000935 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000936
Tim Petersa3a3a032000-11-30 05:22:44 +0000937- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000938
939Tools and other miscellany
940
941- The compiler in Tools/compiler was updated to support the new
942 language features introduced in 2.0: extended print statement, list
943 comprehensions, and augmented assignments. The new compiler should
944 also be backwards compatible with Python 1.5.2; the compiler will
945 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000946 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000947
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000948What's new in 2.0 release candidate 1 (since beta 2)?
949=====================================================
950
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000951What is release candidate 1?
952
953We believe that release candidate 1 will fix all known bugs that we
954intend to fix for the 2.0 final release. This release should be a bit
955more stable than the previous betas. We would like to see even more
956widespread testing before the final release, so we are producing this
957release candidate. The final release will be exactly the same unless
958any show-stopping (or brown bag) bugs are found by testers of the
959release candidate.
960
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000961All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000962to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000963
964Core language, builtins, and interpreter
965
966- A bug that caused crashes when __coerce__ was used with augmented
967 assignment, e.g. +=, was fixed.
968
969- Raise ZeroDivisionError when raising zero to a negative number,
970 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
971 power operator and the result of math.pow(0.0, -2.0) will vary by
972 platform. On Linux, it raises a ValueError.
973
974- A bug in Unicode string interpolation was fixed that occasionally
975 caused errors with formats including "%%". For example, the
976 following expression "%% %s" % u"abc" no longer raises a TypeError.
977
978- Compilation of deeply nested expressions raises MemoryError instead
979 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
980
981- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
982 rendering them useless. They are now written in binary mode again.
983
984Standard library
985
986- Keyword arguments are now accepted for most pattern and match object
987 methods in SRE, the standard regular expression engine.
988
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000989- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000990 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000991
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000992- Several bugs in the Unicode handling and error handling in _tkinter
993 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000994
995- Fix memory management errors in Merge() and Tkapp_Call() routines.
996
997- Several changes were made to cStringIO to make it compatible with
998 the file-like object interface and with StringIO. If operations are
999 performed on a closed object, an exception is raised. The truncate
1000 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001001 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001002
1003- There were many changes made to the linuxaudiodev module and its
1004 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001005 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001006
1007 Note that this module is named poorly, because it should work
1008 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001009 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001010
1011 The module now raises exceptions when errors occur instead of
1012 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1013 audio) and defines a getptr() method that calls the
1014 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1015
1016- The library_version attribute, introduced in an earlier beta, was
1017 removed because it can not be supported with early versions of the C
1018 readline library, which provides no way to determine the version at
1019 compile-time.
1020
1021- The binascii module is now enabled on Win64.
1022
Tim Peters46446d62000-10-09 21:19:31 +00001023- tokenize.py no longer suffers "recursion depth" errors when parsing
1024 programs with very long string literals.
1025
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001026Internals
1027
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001028- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001029 which is called when the interpreter starts up to determine where
1030 the standard library is installed. These vulnerabilities affect all
1031 previous versions of Python and can be exploited by setting very
1032 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1033 setuid Python script, although use of the wrapper in
1034 Misc/setuid-prog.c will eliminate the vulnerability.
1035
1036- Fixed garbage collection bugs in instance creation that were
1037 triggered when errors occurred during initialization. The solution,
1038 applied in cPickle and in PyInstance_New(), is to call
1039 PyObject_GC_Init() after the initialization of the object's
1040 container attributes is complete.
1041
1042- pyexpat adds definitions of PyModule_AddStringConstant and
1043 PyModule_AddObject if the Python version is less than 2.0, which
1044 provides compatibility with PyXML on Python 1.5.2.
1045
1046- If the platform has a bogus definition for LONG_BIT (the number of
1047 bits in a long), an error will be reported at compile time.
1048
1049- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1050 collection crashes and possibly other, unreported crashes.
1051
1052- Fixed a memory leak in _PyUnicode_Fini().
1053
1054Build issues
1055
1056- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001057 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001058 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001059
1060- The mmap.PAGESIZE constant is now initialized using sysconf when
1061 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1062
1063- The md5 file should now compile on all platforms.
1064
1065- The select module now compiles on platforms that do not define
1066 POLLRDNORM and related constants.
1067
1068- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001069 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001070
Jeremy Hylton10921202000-10-09 18:34:12 +00001071- BeOS: A number of changes were made to the build and installation
1072 process. ar-fake now operates on a directory of object files.
1073 dl_export.h is gone, and its macros now appear on the mwcc command
1074 line during build on PPC BeOS.
1075
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001076- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001077 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001078
1079- Cygwin: Support for shared libraries, Tkinter, and sockets.
1080
1081- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1082
1083Tools and other miscellany
1084
1085- Removed debugging prints from main used with freeze.
1086
Tim Peters46446d62000-10-09 21:19:31 +00001087- IDLE auto-indent no longer crashes when it encounters Unicode
1088 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001089
1090What's new in 2.0 beta 2 (since beta 1)?
1091========================================
1092
1093Core language, builtins, and interpreter
1094
Tim Peters482c0212000-09-26 06:33:09 +00001095- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001096 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001097
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001098- Add -h and -V command line options to print the usage message and
1099 Python version number and exit immediately.
1100
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001101- eval() and exec accept Unicode objects as code parameters.
1102
1103- getattr() and setattr() now also accept Unicode objects for the
1104 attribute name, which are converted to strings using the default
1105 encoding before lookup.
1106
1107- Multiplication on string and Unicode now does proper bounds
1108 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1109 string is too long."
1110
1111- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001112 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001113
Jeremy Hylton1b618592000-09-26 05:32:36 +00001114
1115Standard library and extensions
1116
Guido van Rossum5b08f132001-04-16 02:05:23 +00001117- socket module: the OpenSSL code now adds support for RAND_status()
1118 and EGD (Entropy Gathering Device).
1119
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001120- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001121 argument checking; it still takes no arguments.
1122
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001123- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001124
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001125- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001126
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001127- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001128
1129- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001130 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001131
1132- copy: Copy Unicode objects atomically.
1133
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001134- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001135
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001136- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001137
Fred Drake67233bc2000-09-26 16:40:27 +00001138- dbm: Add get() and setdefault() methods to dbm object. Add constant
1139 `library' to module that names the library used. Added doc strings
1140 and method names to error messages. Uses configure to determine
1141 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1142 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001143
1144- distutils: Update to version 0.9.3.
1145
1146- dl: Add several dl.RTLD_ constants.
1147
1148- fpectl: Now supported on FreeBSD.
1149
1150- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1151 found by the collector will be saved in gc.garbage. This is useful
1152 for debugging a program that creates reference cycles.
1153
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001154- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001155 of HTTP class. Do not close socket on zero-length response. Do not
1156 crash when server sends invalid content-length header.
1157
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001158- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001159
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001160- marshal: When reading a short, sign-extend on platforms where shorts
1161 are bigger than 16 bits. When reading a long, repair the unportable
1162 sign extension that was being done for 64-bit machines. (It assumed
1163 that signed right shift sign-extends.)
1164
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001165- operator: Add contains(), invert(), __invert__() as aliases for
1166 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001167
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001168- os: Add support for popen2() and popen3() on all platforms where
1169 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001170
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001171- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001172 clicking on a file in Explorer (or passing the file name to the
1173 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001174
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001175- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001176 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001177
1178- pickle: Now raises ValueError when an invalid pickle that contains
1179 a non-string repr where a string repr was expected. This behavior
1180 matches cPickle.
1181
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001182- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001183
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001184- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001185
1186- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001187 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001188 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001189
1190- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001191 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001192
1193- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001194 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001195 few cycles during startup since the first call to
1196 setdefaultencoding() will initialize the codec registry and the
1197 encodings package.
1198
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001199- socket: Support for size hint in readlines() method of object returned
1200 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001201
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001202- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001203 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001204 is followed by whitespace.
1205
Tim Petersa3a3a032000-11-30 05:22:44 +00001206- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001207
1208- struct: Check ranges for bytes and shorts.
1209
1210- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001211 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001212
1213- Tkinter: Image objects are now guaranteed to have unique ids. Set
1214 event.delta to zero if Tk version doesn't support mousewheel.
1215 Removed some debugging prints.
1216
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001217- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001218
Fred Drake67233bc2000-09-26 16:40:27 +00001219- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001220 which works around a bug in Norton AntiVirus 2000 that leads directly
1221 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001222
1223- xml: New version detection code allows PyXML to override standard
1224 XML package if PyXML version is greater than 0.6.1.
1225
Fred Drake64bb3802000-09-26 16:21:35 +00001226- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1227 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1228 tree only for nodes which are sufficiently interesting to a specific
1229 application. Does not provide the HTML-specific extensions. Still
1230 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001231
Fred Drake64bb3802000-09-26 16:21:35 +00001232- xml.sax: SAX 2 support for Python, including all the handler
1233 interfaces needed to process XML 1.0 compliant XML. Some
1234 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001235
Fred Drake64bb3802000-09-26 16:21:35 +00001236- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1237 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001238
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001239
Jeremy Hylton1b618592000-09-26 05:32:36 +00001240C API
1241
1242- Add three new convenience functions for module initialization --
1243 PyModule_AddObject(), PyModule_AddIntConstant(), and
1244 PyModule_AddStringConstant().
1245
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001246- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001247 removed and add #error to Python.h if NULL isn't defined after
1248 #include of stdio.h.
1249
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001250- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001251 backwards compatibility (at the source level) with old extensions.
1252
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001253- A wrapper API was added for signal() and sigaction(). Instead of
1254 either function, always use PyOS_getsig() to get a signal handler
1255 and PyOS_setsig() to set one. A new convenience typedef
1256 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001257
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001258- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001259 internal data buffer and size of a string object -- or the default
1260 encoded version of a Unicode object.
1261
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001262- PyString_Size() and PyString_AsString() accept Unicode objects.
1263
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001264- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001265 exists). INT_MAX and LONG_MAX will always be defined, even if
1266 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001267
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001268- PyFloat_FromString takes a second argument, pend, that was
1269 effectively useless. It is now officially useless but preserved for
1270 backwards compatibility. If the pend argument is not NULL, *pend is
1271 set to NULL.
1272
1273- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1274 for the attribute name. See note on getattr() above.
1275
1276- A few bug fixes to argument processing for Unicode.
1277 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1278 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1279 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001280 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001281
1282- Py_BuildValue accepts B format (for bgen-generated code).
1283
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001284
Jeremy Hylton1b618592000-09-26 05:32:36 +00001285Internals
1286
1287- On Unix, fix code for finding Python installation directory so that
1288 it works when argv[0] is a relative path.
1289
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001290- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001291 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001292 rather than by generating a copy of the object.
1293
Tim Peters482c0212000-09-26 06:33:09 +00001294- Several of the internal Unicode tables are much smaller now, and
1295 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001296
Jeremy Hylton97693b02000-09-26 17:42:51 +00001297- In the garbage collector: Fixed bug in collection of tuples. Fixed
1298 bug that caused some instances to be removed from the container set
1299 while they were still live. Fixed parsing in gc.set_debug() for
1300 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001301
1302- Fixed refcount problem in instance deallocation that only occurred
1303 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1304
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001305- On Windows, getpythonregpath is now protected against null data in
1306 registry key.
1307
1308- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001309 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001310
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001311
Jeremy Hylton1b618592000-09-26 05:32:36 +00001312Build and platform-specific issues
1313
1314- Better support of GNU Pth via --with-pth configure option.
1315
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001316- Python/C API now properly exposed to dynamically-loaded extension
1317 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001318
1319- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1320 Don't define MS_SYNC to be zero when it is undefined. Added missing
1321 prototypes in posixmodule.c.
1322
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001323- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001324 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001325
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001326- Fix largefile support on older NetBSD systems and OpenBSD by adding
1327 define for TELL64.
1328
1329
1330Tools and other miscellany
1331
1332- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1333
1334- freeze: The modulefinder now works with 2.0 opcodes.
1335
Tim Petersa3a3a032000-11-30 05:22:44 +00001336- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001337 Move hackery of sys.argv until after the Tk instance has been
1338 created, which allows the application-specific Tkinter
1339 initialization to be executed if present; also pass an explicit
1340 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001341
Jeremy Hylton1b618592000-09-26 05:32:36 +00001342
1343What's new in 2.0 beta 1?
1344=========================
1345
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001346Source Incompatibilities
1347------------------------
1348
1349None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1350such as single-argument append(), connect() and bind(), and changes to
1351str(long) and repr(float).
1352
1353
1354Binary Incompatibilities
1355------------------------
1356
1357- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1358with Python 2.0; these extensions will have to be rebuilt for Python
13592.0.
1360
1361- On Windows, attempting to import a third party extension built for
1362Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1363can do about this. Check your PYTHONPATH environment variable!
1364
1365- Python bytecode files (*.pyc and *.pyo) are not compatible between
1366releases.
1367
1368
1369Overview of Changes Since 1.6
1370-----------------------------
1371
1372There are many new modules (including brand new XML support through
1373the xml package, and i18n support through the gettext module); a list
1374of all new modules is included below. Lots of bugs have been fixed.
1375
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001376The process for making major new changes to the language has changed
1377since Python 1.6. Enhancements must now be documented by a Python
1378Enhancement Proposal (PEP) before they can be accepted.
1379
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001380There are several important syntax enhancements, described in more
1381detail below:
1382
1383 - Augmented assignment, e.g. x += 1
1384
1385 - List comprehensions, e.g. [x**2 for x in range(10)]
1386
1387 - Extended import statement, e.g. import Module as Name
1388
1389 - Extended print statement, e.g. print >> file, "Hello"
1390
1391Other important changes:
1392
1393 - Optional collection of cyclical garbage
1394
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001395Python Enhancement Proposal (PEP)
1396---------------------------------
1397
1398PEP stands for Python Enhancement Proposal. A PEP is a design
1399document providing information to the Python community, or describing
1400a new feature for Python. The PEP should provide a concise technical
1401specification of the feature and a rationale for the feature.
1402
1403We intend PEPs to be the primary mechanisms for proposing new
1404features, for collecting community input on an issue, and for
1405documenting the design decisions that have gone into Python. The PEP
1406author is responsible for building consensus within the community and
1407documenting dissenting opinions.
1408
1409The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001410
1411Augmented Assignment
1412--------------------
1413
1414This must have been the most-requested feature of the past years!
1415Eleven new assignment operators were added:
1416
Guido van Rossume905e952000-09-05 12:42:46 +00001417 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001418
1419For example,
1420
1421 A += B
1422
1423is similar to
1424
1425 A = A + B
1426
1427except that A is evaluated only once (relevant when A is something
1428like dict[index].attr).
1429
1430However, if A is a mutable object, A may be modified in place. Thus,
1431if A is a number or a string, A += B has the same effect as A = A+B
1432(except A is only evaluated once); but if a is a list, A += B has the
1433same effect as A.extend(B)!
1434
1435Classes and built-in object types can override the new operators in
1436order to implement the in-place behavior; the not-in-place behavior is
1437used automatically as a fallback when an object doesn't implement the
1438in-place behavior. For classes, the method name is derived from the
1439method name for the corresponding not-in-place operator by inserting
1440an 'i' in front of the name, e.g. __iadd__ implements in-place
1441__add__.
1442
1443Augmented assignment was implemented by Thomas Wouters.
1444
1445
1446List Comprehensions
1447-------------------
1448
1449This is a flexible new notation for lists whose elements are computed
1450from another list (or lists). The simplest form is:
1451
1452 [<expression> for <variable> in <sequence>]
1453
Guido van Rossum56db0952000-09-06 23:34:25 +00001454For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001455This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001456
1457You can also add a condition:
1458
1459 [<expression> for <variable> in <sequence> if <condition>]
1460
1461For example, [w for w in words if w == w.lower()] would yield the list
1462of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001463than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001464
1465You can also have nested for loops and more than one 'if' clause. For
1466example, here's a function that flattens a sequence of sequences::
1467
1468 def flatten(seq):
1469 return [x for subseq in seq for x in subseq]
1470
1471 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1472
1473This prints
1474
1475 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1476
1477List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001478Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001479
1480
1481Extended Import Statement
1482-------------------------
1483
1484Many people have asked for a way to import a module under a different
1485name. This can be accomplished like this:
1486
1487 import foo
1488 bar = foo
1489 del foo
1490
1491but this common idiom gets old quickly. A simple extension of the
1492import statement now allows this to be written as follows:
1493
1494 import foo as bar
1495
1496There's also a variant for 'from ... import':
1497
1498 from foo import bar as spam
1499
1500This also works with packages; e.g. you can write this:
1501
1502 import test.regrtest as regrtest
1503
1504Note that 'as' is not a new keyword -- it is recognized only in this
1505context (this is only possible because the syntax for the import
1506statement doesn't involve expressions).
1507
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001508Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001509
1510
1511Extended Print Statement
1512------------------------
1513
1514Easily the most controversial new feature, this extension to the print
1515statement adds an option to make the output go to a different file
1516than the default sys.stdout.
1517
1518For example, to write an error message to sys.stderr, you can now
1519write:
1520
1521 print >> sys.stderr, "Error: bad dog!"
1522
1523As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001524evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001525
1526 print >> None, "Hello world"
1527
1528is equivalent to
1529
1530 print "Hello world"
1531
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001532Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001533
1534
1535Optional Collection of Cyclical Garbage
1536---------------------------------------
1537
1538Python is now equipped with a garbage collector that can hunt down
1539cyclical references between Python objects. It's no replacement for
1540reference counting; in fact, it depends on the reference counts being
1541correct, and decides that a set of objects belong to a cycle if all
1542their reference counts can be accounted for from their references to
1543each other. This devious scheme was first proposed by Eric Tiedemann,
1544and brought to implementation by Neil Schemenauer.
1545
1546There's a module "gc" that lets you control some parameters of the
1547garbage collection. There's also an option to the configure script
1548that lets you enable or disable the garbage collection. In 2.0b1,
1549it's on by default, so that we (hopefully) can collect decent user
1550experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001551performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001552off by default in the final 2.0 release.
1553
1554
1555Smaller Changes
1556---------------
1557
1558A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1559map(None, seq1, seq2, ...) when the sequences have the same length;
1560i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1561the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001562zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001563
1564sys.version_info is a tuple (major, minor, micro, level, serial).
1565
1566Dictionaries have an odd new method, setdefault(key, default).
1567dict.setdefault(key, default) returns dict[key] if it exists; if not,
1568it sets dict[key] to default and returns that value. Thus:
1569
1570 dict.setdefault(key, []).append(item)
1571
1572does the same work as this common idiom:
1573
1574 if not dict.has_key(key):
1575 dict[key] = []
1576 dict[key].append(item)
1577
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001578There are two new variants of SyntaxError that are raised for
1579indentation-related errors: IndentationError and TabError.
1580
1581Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1582escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001583
1584The limits on the size of expressions and file in Python source code
1585have been raised from 2**16 to 2**32. Previous versions of Python
1586were limited because the maximum argument size the Python VM accepted
1587was 2**16. This limited the size of object constructor expressions,
1588e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1589limit was raised thanks to a patch by Charles Waldman that effectively
1590fixes the problem. It is now much more likely that you will be
1591limited by available memory than by an arbitrary limit in Python.
1592
1593The interpreter's maximum recursion depth can be modified by Python
1594programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1595limit is the maximum number of recursive calls that can be made by
1596Python code. The limit exists to prevent infinite recursion from
1597overflowing the C stack and causing a core dump. The default value is
15981000. The maximum safe value for a particular platform can be found
1599by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001600
1601New Modules and Packages
1602------------------------
1603
1604atexit - for registering functions to be called when Python exits.
1605
1606imputil - Greg Stein's alternative API for writing custom import
1607hooks.
1608
1609pyexpat - an interface to the Expat XML parser, contributed by Paul
1610Prescod.
1611
1612xml - a new package with XML support code organized (so far) in three
1613subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1614would fill a volume. There's a special feature whereby a
1615user-installed package named _xmlplus overrides the standard
1616xmlpackage; this is intended to give the XML SIG a hook to distribute
1617backwards-compatible updates to the standard xml package.
1618
1619webbrowser - a platform-independent API to launch a web browser.
1620
1621
Guido van Rossume905e952000-09-05 12:42:46 +00001622Changed Modules
1623---------------
1624
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001625array -- new methods for array objects: count, extend, index, pop, and
1626remove
1627
1628binascii -- new functions b2a_hex and a2b_hex that convert between
1629binary data and its hex representation
1630
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001631calendar -- Many new functions that support features including control
1632over which day of the week is the first day, returning strings instead
1633of printing them. Also new symbolic constants for days of week,
1634e.g. MONDAY, ..., SUNDAY.
1635
1636cgi -- FieldStorage objects have a getvalue method that works like a
1637dictionary's get method and returns the value attribute of the object.
1638
1639ConfigParser -- The parser object has new methods has_option,
1640remove_section, remove_option, set, and write. They allow the module
1641to be used for writing config files as well as reading them.
1642
1643ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001644optionally support the RFC 959 REST command.
1645
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001646gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001647
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001648httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1649the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001650
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001651locale -- implement getdefaultlocale for Win32 and Macintosh
1652
1653marshal -- no longer dumps core when marshaling deeply nested or
1654recursive data structures
1655
1656os -- new functions isatty, seteuid, setegid, setreuid, setregid
1657
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001658os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1659support under Unix.
1660
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001661os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001662
1663os.path -- fix semantics of os.path.commonprefix
1664
1665smtplib -- support for sending very long messages
1666
1667socket -- new function getfqdn()
1668
1669readline -- new functions to read, write and truncate history files.
1670The readline section of the library reference manual contains an
1671example.
1672
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001673select -- add interface to poll system call
1674
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001675shutil -- new copyfileobj function
1676
1677SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1678HTTP server.
1679
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001680Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001681
1682urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001683e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001684
1685whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001686
1687
1688Obsolete Modules
1689----------------
1690
1691None. However note that 1.6 made a whole slew of modules obsolete:
1692stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1693poly, zmod, strop, util, whatsound.
1694
1695
1696Changed, New, Obsolete Tools
1697----------------------------
1698
Tim Peters8b092332000-09-05 20:15:25 +00001699None.
Guido van Rossume905e952000-09-05 12:42:46 +00001700
1701
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001702C-level Changes
1703---------------
1704
1705Several cleanup jobs were carried out throughout the source code.
1706
1707All C code was converted to ANSI C; we got rid of all uses of the
1708Py_PROTO() macro, which makes the header files a lot more readable.
1709
1710Most of the portability hacks were moved to a new header file,
1711pyport.h; several other new header files were added and some old
1712header files were removed, in an attempt to create a more rational set
1713of header files. (Few of these ever need to be included explicitly;
1714they are all included by Python.h.)
1715
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001716Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001717and Win64, especially for the new Intel Itanium processor. Mick also
1718added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001719
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001720The C APIs to return an object's size have been update to consistently
1721use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1722previous versions, the abstract interfaces used PyXXX_Length and the
1723concrete interfaces used PyXXX_Size. The old names,
1724e.g. PyObject_Length, are still available for backwards compatibility
1725at the API level, but are deprecated.
1726
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001727The PyOS_CheckStack function has been implemented on Windows by
1728Fredrik Lundh. It prevents Python from failing with a stack overflow
1729on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001730
1731The GC changes resulted in creation of two new slots on object,
1732tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001733the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001734
1735The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001736C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001737
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001738PyErr_Format has been updated to automatically calculate the size of
1739the buffer needed to hold the formatted result string. This change
1740prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001741
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001742New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001743
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001744PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1745that are the same as their non-Ex counterparts except they take an
1746extra flag argument that tells them to close the file when done.
1747
1748XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001749
Tim Peters8b092332000-09-05 20:15:25 +00001750
1751Windows Changes
1752---------------
1753
1754New popen2/popen3/peopen4 in os module (see Changed Modules above).
1755
1756os.popen is much more usable on Windows 95 and 98. See Microsoft
1757Knowledge Base article Q150956. The Win9x workaround described there
1758is implemented by the new w9xpopen.exe helper in the root of your
1759Python installation. Note that Python uses this internally; it is not
1760a standalone program.
1761
1762Administrator privileges are no longer required to install Python
1763on Windows NT or Windows 2000. If you have administrator privileges,
1764Python's registry info will be written under HKEY_LOCAL_MACHINE.
1765Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001766under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001767uses of Python, but will prevent some advanced uses from working
1768(for example, running a Python script as an NT service, or possibly
1769from CGI).
1770
1771[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1772installer; instead, it installs the needed Tcl/Tk files directly in the
1773Python directory. If you already have a Tcl/Tk installation, this
1774wastes some disk space (about 4 Megs) but avoids problems with
1775conflicting Tcl/Tk installations, and makes it much easier for Python
1776to ensure that Tcl/Tk can find all its files.
1777
1778[This was new in 1.6] The Windows installer now installs by default in
1779\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1780
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001781
1782Updates to the changes between 1.5.2 and 1.6
1783--------------------------------------------
1784
1785The 1.6 NEWS file can't be changed after the release is done, so here
1786is some late-breaking news:
1787
1788New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1789and changes to getlocale() and setlocale().
1790
1791The new module is now enabled per default.
1792
1793It is not true that the encodings codecs cannot be used for normal
1794strings: the string.encode() (which is also present on 8-bit strings
1795!) allows using them for 8-bit strings too, e.g. to convert files from
1796cp1252 (Windows) to latin-1 or vice-versa.
1797
1798Japanese codecs are available from Tamito KAJIYAMA:
1799http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1800
1801
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001802======================================================================