blob: 92882d2057fec9d2895e7401141fe9efbf6a2193 [file] [log] [blame]
Guido van Rossumffe13be2001-04-16 18:46:45 +00001What's New in Python 2.1 (final)?
2=================================
3
4We only changed a few things since the last release candidate, all in
5Python library code:
6
7- A bug in the locale module was fixed that affected locales which
8 define no grouping for numeric formatting.
9
10- A few bugs in the weakref module's implementations of weak
11 dictionaries (WeakValueDictionary and WeakKeyDictionary) were fixed,
12 and the test suite was updated to check for these bugs.
13
14- An old bug in the os.path.walk() function (introduced in Python
15 2.0!) was fixed: a non-existent file would cause an exception
16 instead of being ignored.
17
18- Fixed a few bugs in the new symtable module found by Neil Norwitz's
19 PyChecker.
20
21
Guido van Rossum5b08f132001-04-16 02:05:23 +000022What's New in Python 2.1c2?
23===========================
Barry Warsaw11e89c72001-04-11 20:37:57 +000024
Guido van Rossum5b08f132001-04-16 02:05:23 +000025A flurry of small changes, and one showstopper fixed in the nick of
26time made it necessary to release another release candidate. The list
27here is the *complete* list of patches (except version updates):
Guido van Rossum4fb60362001-04-13 00:46:14 +000028
Guido van Rossum5b08f132001-04-16 02:05:23 +000029Core
Guido van Rossum4fb60362001-04-13 00:46:14 +000030
Guido van Rossum5b08f132001-04-16 02:05:23 +000031- Tim discovered a nasty bug in the dictionary code, caused by
32 PyDict_Next() calling dict_resize(), and the GC code's use of
33 PyDict_Next() violating an assumption in dict_items(). This was
34 fixed with considerable amounts of band-aid, but the net effect is a
35 saner and more robust implementation.
36
37- Made a bunch of symbols static that were accidentally global.
38
39Build and Ports
40
41- The setup.py script didn't check for a new enough version of zlib
42 (1.1.3 is needed). Now it does.
43
44- Changed "make clean" target to also remove shared libraries.
45
46- Added a more general warning about the SGI Irix optimizer to README.
47
48Library
49
50- Fix a bug in urllib.basejoin("http://host", "../file.html") which
51 omitted the slash between host and file.html.
52
53- The mailbox module's _Mailbox class contained a completely broken
54 and undocumented seek() method. Ripped it out.
55
56- Fixed a bunch of typos in various library modules (urllib2, smtpd,
57 sgmllib, netrc, chunk) found by Neil Norwitz's PyChecker.
58
59- Fixed a few last-minute bugs in unittest.
60
61Extensions
62
63- Reverted the patch to the OpenSSL code in socketmodule.c to support
64 RAND_status() and the EGD, and the subsequent patch that tried to
65 fix it for pre-0.9.5 versions; the problem with the patch is that on
66 some systems it issues a warning whenever socket is imported, and
67 that's unacceptable.
68
69Tests
70
71- Fixed the pickle tests to work with "import test.test_pickle".
72
73- Tweaked test_locale.py to actually run the test Windows.
74
75- In distutils/archive_util.py, call zipfile.ZipFile() with mode "w",
76 not "wb" (which is not a valid mode at all).
77
78- Fix pstats browser crashes. Import readline if it exists to make
79 the user interface nicer.
80
81- Add "import thread" to the top of test modules that import the
82 threading module (test_asynchat and test_threadedtempfile). This
83 prevents test failures caused by a broken threading module resulting
84 from a previously caught failed import.
85
86- Changed test_asynchat.py to set the SO_REUSEADDR option; this was
87 needed on some platforms (e.g. Solaris 8) when the tests are run
88 twice in succession.
89
90- Skip rather than fail test_sunaudiodev if no audio device is found.
91
92
93What's New in Python 2.1c1?
94===========================
95
96This list was significantly updated when 2.1c2 was released; the 2.1c1
97release didn't mention most changes that were actually part of 2.1c1:
98
99Legal
100
101- Copyright was assigned to the Python Software Foundation (PSF) and a
102 PSF license (very similar to the CNRI license) was added.
103
104- The CNRI copyright notice was updated to include 2001.
105
106Core
Barry Warsaw11e89c72001-04-11 20:37:57 +0000107
Guido van Rossumc9932722001-04-12 02:31:27 +0000108- After a public outcry, assignment to __debug__ is no longer illegal;
109 instead, a warning is issued. It will become illegal in 2.2.
110
Guido van Rossum5b08f132001-04-16 02:05:23 +0000111- Fixed a core dump with "%#x" % 0, and changed the semantics so that
112 "%#x" now always prepends "0x", even if the value is zero.
113
114- Fixed some nits in the bytecode compiler.
115
116- Fixed core dumps when calling certain kinds of non-functions.
117
118- Fixed various core dumps caused by reference count bugs.
119
120Build and Ports
121
122- Use INSTALL_SCRIPT to install script files.
123
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000124- New port: SCO Unixware 7, by Billy G. Allie.
125
Guido van Rossum5b08f132001-04-16 02:05:23 +0000126- Updated RISCOS port.
127
128- Updated BeOS port and notes.
129
130- Various other porting problems resolved.
131
132Library
133
134- The TERMIOS and SOCKET modules are now truly obsolete and
135 unnecessary. Their symbols are incorporated in the termios and
136 socket modules.
137
138- Fixed some 64-bit bugs in pickle, cPickle, and struct, and added
139 better tests for pickling.
140
141- threading: make Condition.wait() robust against KeyboardInterrupt.
142
143- zipfile: add support to zipfile to support opening an archive
144 represented by an open file rather than a file name. Fix bug where
145 the archive was not properly closed. Fixed a bug in this bugfix
146 where flush() was called for a read-only file.
147
148- imputil: added an uninstall() method to the ImportManager.
149
150- Canvas: fixed bugs in lower() and tkraise() methods.
151
152- SocketServer: API change (added overridable close_request() method)
153 so that the TCP server can explicitly close the request.
154
155- pstats: Eric Raymond added a simple interactive statistics browser,
156 invoked when the module is run as a script.
157
158- locale: fixed a problem in format().
159
160- webbrowser: made it work when the BROWSER environment variable has a
161 value like "/usr/bin/netscape". Made it auto-detect Konqueror for
162 KDE 2. Fixed some other nits.
163
164- unittest: changes to allow using a different exception than
165 AssertionError, and added a few more function aliases. Some other
166 small changes.
167
168- urllib, urllib2: fixed redirect problems and a coupleof other nits.
169
170- asynchat: fixed a critical bug in asynchat that slipped through the
171 2.1b2 release. Fixed another rare bug.
172
173- Fix some unqualified except: clauses (always a bad code example).
174
175XML
176
177- pyexpat: new API get_version_string().
178
179- Fixed some minidom bugs.
180
181Extensions
182
183- Fixed a core dump in _weakref. Removed the weakref.mapping()
184 function (it adds nothing to the API).
185
186- Rationalized the use of header files in the readline module, to make
187 it compile (albeit with some warnings) with the very recent readline
188 4.2, without breaking for earlier versions.
189
190- Hopefully fixed a buffering problem in linuxaudiodev.
191
192- Attempted a fix to make the OpenSSL support in the socket module
193 work again with pre-0.9.5 versions of OpenSSL.
194
195Tests
196
197- Added a test case for asynchat and asyncore.
198
199- Removed coupling between tests where one test failing could break
200 another.
201
202Tools
203
204- Ping added an interactive help browser to pydoc, fixed some nits
205 in the rest of the pydoc code, and added some features to his
206 inspect module.
207
208- An updated python-mode.el version 4.1 which integrates Ken
209 Manheimer's pdbtrack.el. This makes debugging Python code via pdb
210 much nicer in XEmacs and Emacs. When stepping through your program
211 with pdb, in either the shell window or the *Python* window, the
212 source file and line will be tracked by an arrow. Very cool!
213
214- IDLE: syntax warnings in interactive mode are changed into errors.
215
216- Some improvements to Tools/webchecker (ignore some more URL types,
217 follow some more links).
218
219- Brought the Tools/compiler package up to date.
Guido van Rossum34d37dc2001-04-11 21:03:32 +0000220
Barry Warsaw11e89c72001-04-11 20:37:57 +0000221
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000222What's New in Python 2.1 beta 2?
223================================
224
Guido van Rossum053ae352001-03-22 14:17:21 +0000225(Unlisted are many fixed bugs, more documentation, etc.)
226
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000227Core language, builtins, and interpreter
228
Guido van Rossum053ae352001-03-22 14:17:21 +0000229- The nested scopes work (enabled by "from __future__ import
230 nested_scopes") is completed; in particular, the future now extends
231 into code executed through exec, eval() and execfile(), and into the
232 interactive interpreter.
233
234- When calling a base class method (e.g. BaseClass.__init__(self)),
235 this is now allowed even if self is not strictly spoken a class
236 instance (e.g. when using metaclasses or the Don Beaudry hook).
237
238- Slice objects are now comparable but not hashable; this prevents
239 dict[:] from being accepted but meaningless.
240
241- Complex division is now calculated using less braindead algorithms.
242 This doesn't change semantics except it's more likely to give useful
243 results in extreme cases. Complex repr() now uses full precision
244 like float repr().
245
246- sgmllib.py now calls handle_decl() for simple <!...> declarations.
247
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000248- It is illegal to assign to the name __debug__, which is set when the
249 interpreter starts. It is effectively a compile-time constant.
250
251- A warning will be issued if a global statement for a variable
252 follows a use or assignment of that variable.
253
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000254Standard library
255
Guido van Rossum053ae352001-03-22 14:17:21 +0000256- unittest.py, a unit testing framework by Steve Purcell (PyUNIT,
257 inspired by JUnit), is now part of the standard library. You now
258 have a choice of two testing frameworks: unittest requires you to
259 write testcases as separate code, doctest gathers them from
260 docstrings. Both approaches have their advantages and
261 disadvantages.
262
263- A new module Tix was added, which wraps the Tix extension library
264 for Tk. With that module, it is not necessary to statically link
265 Tix with _tkinter, since Tix will be loaded with Tcl's "package
266 require" command. See Demo/tix/.
267
268- tzparse.py is now obsolete.
269
270- In gzip.py, the seek() and tell() methods are removed -- they were
271 non-functional anyway, and it's better if callers can test for their
272 existence with hasattr().
273
274Python/C API
275
276- PyDict_Next(): it is now safe to call PyDict_SetItem() with a key
277 that's already in the dictionary during a PyDict_Next() iteration.
278 This used to fail occasionally when a dictionary resize operation
279 could be triggered that would rehash all the keys. All other
280 modifications to the dictionary are still off-limits during a
281 PyDict_Next() iteration!
282
283- New extended APIs related to passing compiler variables around.
284
285- New abstract APIs PyObject_IsInstance(), PyObject_IsSubclass()
286 implement isinstance() and issubclass().
287
288- Py_BuildValue() now has a "D" conversion to create a Python complex
289 number from a Py_complex C value.
Martin v. Löwis0411f6f2001-03-21 08:01:39 +0000290
Fred Drake4e262a92001-03-22 18:26:47 +0000291- Extensions types which support weak references must now set the
292 field allocated for the weak reference machinery to NULL themselves;
293 this is done to avoid the cost of checking each object for having a
294 weakly referencable type in PyObject_INIT(), since most types are
295 not weakly referencable.
296
Jeremy Hyltonf626db72001-03-23 14:18:27 +0000297- PyFrame_FastToLocals() and PyFrame_LocalsToFast() copy bindings for
298 free variables and cell variables to and from the frame's f_locals.
299
300- Variants of several functions defined in pythonrun.h have been added
301 to support the nested_scopes future statement. The variants all end
302 in Flags and take an extra argument, a PyCompilerFlags *; examples:
303 PyRun_AnyFileExFlags(), PyRun_InteractiveLoopFlags(). These
304 variants may be removed in Python 2.2, when nested scopes are
305 mandatory.
306
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000307Distutils
308
309- the sdist command now writes a PKG-INFO file, as described in PEP 241,
310 into the release tree.
311
312- several enhancements to the bdist_wininst command from Thomas Heller
313 (an uninstaller, more customization of the installer's display)
314
315- from Jack Jansen: added Mac-specific code to generate a dialog for
316 users to specify the command-line (because providing a command-line with
317 MacPython is awkward). Jack also made various fixes for the Mac
318 and the Metrowerks compiler.
319
320- added 'platforms' and 'keywords' to the set of metadata that can be
Andrew M. Kuchling68ad64a2001-03-31 02:42:42 +0000321 specified for a distribution.
Andrew M. Kuchling8e9972c2001-03-22 15:42:08 +0000322
323- applied patches from Jason Tishler to make the compiler class work with
324 Cygwin.
325
326
Tim Peters2fe289a2001-03-01 22:19:38 +0000327What's New in Python 2.1 beta 1?
328================================
Tim Petersd66595f2001-02-04 03:09:53 +0000329
330Core language, builtins, and interpreter
331
Guido van Rossum9d0fbde2001-03-02 14:00:32 +0000332- Following an outcry from the community about the amount of code
333 broken by the nested scopes feature introduced in 2.1a2, we decided
334 to make this feature optional, and to wait until Python 2.2 (or at
335 least 6 months) to make it standard. The option can be enabled on a
336 per-module basis by adding "from __future__ import nested_scopes" at
337 the beginning of a module (before any other statements, but after
338 comments and an optional docstring). See PEP 236 (Back to the
339 __future__) for a description of the __future__ statement. PEP 227
340 (Statically Nested Scopes) has been updated to reflect this change,
341 and to clarify the semantics in a number of endcases.
342
343- The nested scopes code, when enabled, has been hardened, and most
344 bugs and memory leaks in it have been fixed.
345
346- Compile-time warnings are now generated for a number of conditions
347 that will break or change in meaning when nested scopes are enabled:
348
349 - Using "from...import *" or "exec" without in-clause in a function
350 scope that also defines a lambda or nested function with one or
351 more free (non-local) variables. The presence of the import* or
352 bare exec makes it impossible for the compiler to determine the
353 exact set of local variables in the outer scope, which makes it
354 impossible to determine the bindings for free variables in the
355 inner scope. To avoid the warning about import *, change it into
356 an import of explicitly name object, or move the import* statement
357 to the global scope; to avoid the warning about bare exec, use
358 exec...in... (a good idea anyway -- there's a possibility that
359 bare exec will be deprecated in the future).
360
361 - Use of a global variable in a nested scope with the same name as a
362 local variable in a surrounding scope. This will change in
363 meaning with nested scopes: the name in the inner scope will
364 reference the variable in the outer scope rather than the global
365 of the same name. To avoid the warning, either rename the outer
366 variable, or use a global statement in the inner function.
367
Neil Schemenauera35c6882001-02-27 04:45:05 +0000368- An optional object allocator has been included. This allocator is
369 optimized for Python objects and should be faster and use less memory
370 than the standard system allocator. It is not enabled by default
371 because of possible thread safety problems. The allocator is only
372 protected by the Python interpreter lock and it is possible that some
373 extension modules require a thread safe allocator. The object
374 allocator can be enabled by providing the "--with-pymalloc" option to
375 configure.
376
Tim Petersd66595f2001-02-04 03:09:53 +0000377Standard library
378
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000379- pyexpat now detects the expat version if expat.h defines it. A
380 number of additional handlers are provided, which are only available
381 since expat 1.95. In addition, the methods SetParamEntityParsing and
382 GetInputContext of Parser objects are available with 1.95.x
383 only. Parser objects now provide the ordered_attributes and
384 specified_attributes attributes. A new module expat.model was added,
385 which offers a number of additional constants if 1.95.x is used.
386
387- xml.dom offers the new functions registerDOMImplementation and
388 getDOMImplementation.
389
390- xml.dom.minidom offers a toprettyxml method. A number of DOM
391 conformance issues have been resolved. In particular, Element now
392 has an hasAttributes method, and the handling of namespaces was
393 improved.
394
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000395- Ka-Ping Yee contributed two new modules: inspect.py, a module for
396 getting information about live Python code, and pydoc.py, a module
397 for interactively converting docstrings to HTML or text.
398 Tools/scripts/pydoc, which is now automatically installed into
Tim Peters1eff7962001-03-01 02:31:33 +0000399 <prefix>/bin, uses pydoc.py to display documentation; try running
Guido van Rossume3955a82001-03-02 14:05:59 +0000400 "pydoc -h" for instructions. "pydoc -g" pops up a small GUI that
401 lets you browse the module docstrings using a web browser.
Andrew M. Kuchlingd6a1d792001-02-28 21:05:42 +0000402
Tim Peters1eff7962001-03-01 02:31:33 +0000403- New library module difflib.py, primarily packaging the SequenceMatcher
404 class at the heart of the popular ndiff.py file-comparison tool.
405
406- doctest.py (a framework for verifying Python code examples in docstrings)
407 is now part of the std library.
408
Tim Petersd66595f2001-02-04 03:09:53 +0000409Windows changes
410
Guido van Rossume3955a82001-03-02 14:05:59 +0000411- A new entry in the Start menu, "Module Docs", runs "pydoc -g" -- a
412 small GUI that lets you browse the module docstrings using your
413 default web browser.
414
Tim Peters1eff7962001-03-01 02:31:33 +0000415- Import is now case-sensitive. PEP 235 (Import on Case-Insensitive
416 Platforms) is implemented. See
417
418 http://python.sourceforge.net/peps/pep-0235.html
419
420 for full details, especially the "Current Lower-Left Semantics" section.
421 The new Windows import rules are simpler than before:
422
423 A. If the PYTHONCASEOK environment variable exists, same as
424 before: silently accept the first case-insensitive match of any
425 kind; raise ImportError if none found.
426
427 B. Else search sys.path for the first case-sensitive match; raise
428 ImportError if none found.
429
430 The same rules have been implented on other platforms with case-
431 insensitive but case-preserving filesystems too (including Cygwin, and
432 several flavors of Macintosh operating systems).
Tim Petersd66595f2001-02-04 03:09:53 +0000433
Tim Peters25a9ce32001-02-19 07:06:36 +0000434- winsound module: Under Win9x, winsound.Beep() now attempts to simulate
435 what it's supposed to do (and does do under NT and 2000) via direct
436 port manipulation. It's unknown whether this will work on all systems,
Tim Peters1eff7962001-03-01 02:31:33 +0000437 but it does work on my Win98SE systems now and was known to be useless on
Tim Peters25a9ce32001-02-19 07:06:36 +0000438 all Win9x systems before.
439
Tim Peters1eff7962001-03-01 02:31:33 +0000440- Build: Subproject _test (effectively) renamed to _testcapi.
441
Tim Peters2fe289a2001-03-01 22:19:38 +0000442New platforms
443
444- 2.1 should compile and run out of the box under MacOS X, even using HFS+.
445 Thanks to Steven Majewski!
446
447- 2.1 should compile and run out of the box on Cygwin. Thanks to Jason
448 Tishler!
449
Guido van Rossum9089b272001-03-02 06:49:50 +0000450- 2.1 contains new files and patches for RISCOS, thanks to Dietmar
451 Schwertberger! See RISCOS/README for more information -- it seems
452 that because of the bizarre filename conventions on RISCOS, no port
453 to that platform is easy. Note that the new variable os.endsep is
454 silently supported in order to make life easier on this platform,
455 but we don't advertise it because it's not worth for most folks to
456 care about RISCOS portability.
457
Tim Peters25a9ce32001-02-19 07:06:36 +0000458
Tim Petersd7b5e882001-01-25 03:36:26 +0000459What's New in Python 2.1 alpha 2?
460=================================
Tim Peters40ead762001-01-27 05:35:26 +0000461
Tim Petersd7b5e882001-01-25 03:36:26 +0000462Core language, builtins, and interpreter
463
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000464- Scopes nest. If a name is used in a function or class, but is not
465 local, the definition in the nearest enclosing function scope will
466 be used. One consequence of this change is that lambda statements
467 could reference variables in the namespaces where the lambda is
468 defined. In some unusual cases, this change will break code.
469
470 In all previous version of Python, names were resolved in exactly
471 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000472 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +0000473 function A is defined within a function B, the names bound in B are
474 not visible in A. The new rules make names bound in B visible in A,
475 unless A contains a name binding that hides the binding in B.
476
477 Section 4.1 of the reference manual describes the new scoping rules
478 in detail. The test script in Lib/test/test_scope.py demonstrates
479 some of the effects of the change.
480
481 The new rules will cause existing code to break if it defines nested
482 functions where an outer function has local variables with the same
483 name as globals or builtins used by the inner function. Example:
484
485 def munge(str):
486 def helper(x):
487 return str(x)
488 if type(str) != type(''):
489 str = helper(str)
490 return str.strip()
491
492 Under the old rules, the name str in helper() is bound to the
493 builtin function str(). Under the new rules, it will be bound to
494 the argument named str and an error will occur when helper() is
495 called.
496
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000497- The compiler will report a SyntaxError if "from ... import *" occurs
498 in a function or class scope. The language reference has documented
499 that this case is illegal, but the compiler never checked for it.
500 The recent introduction of nested scope makes the meaning of this
501 form of name binding ambiguous. In a future release, the compiler
502 may allow this form when there is no possibility of ambiguity.
503
Tim Peters40ead762001-01-27 05:35:26 +0000504- repr(string) is easier to read, now using hex escapes instead of octal,
505 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
506
507 >>> "\texample \r\n" + chr(0) + chr(255)
508 '\texample \r\n\x00\xff' # in 2.1
509 '\011example \015\012\000\377' # in 2.0
510
Moshe Zadka6af0ce02001-01-29 06:41:00 +0000511- Functions are now compared and hashed by identity, not by value, since
512 the func_code attribute is writable.
513
Fred Drakefb9d7122001-02-01 20:00:40 +0000514- Weak references (PEP 205) have been added. This involves a few
515 changes in the core, an extension module (_weakref), and a Python
516 module (weakref). The weakref module is the public interface. It
517 includes support for "explicit" weak references, proxy objects, and
518 mappings with weakly held values.
519
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000520- A 'continue' statement can now appear in a try block within the body
521 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +0000522 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +0000523
Tim Petersd7b5e882001-01-25 03:36:26 +0000524Standard library
525
Barry Warsaw30dbd142001-01-31 22:14:01 +0000526- mailbox.py now has a new class, PortableUnixMailbox which is
527 identical to UnixMailbox but uses a more portable scheme for
528 determining From_ separators. Also, the constructors for all the
529 classes in this module have a new optional `factory' argument, which
530 is a callable used when new message classes must be instantiated by
531 the next() method.
532
Tim Petersd7b5e882001-01-25 03:36:26 +0000533- random.py is now self-contained, and offers all the functionality of
534 the now-deprecated whrandom.py. See the docs for details. random.py
535 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +0000536 and restoring the internal state of the generator; and jumpahead(n),
537 for quickly forcing the internal state to be the same as if n calls to
538 random() had been made. The latter is particularly useful for multi-
539 threaded programs, creating one instance of the random.Random() class for
540 each thread, then using .jumpahead() to force each instance to use a
541 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +0000542
Tim Peters0de88fc2001-02-01 04:59:18 +0000543- random.py's seed() function is new. For bit-for-bit compatibility with
544 prior releases, use the whseed function instead. The new seed function
545 addresses two problems: (1) The old function couldn't produce more than
546 about 2**24 distinct internal states; the new one about 2**45 (the best
547 that can be done in the Wichmann-Hill generator). (2) The old function
548 sometimes produced identical internal states when passed distinct
549 integers, and there was no simple way to predict when that would happen;
550 the new one guarantees to produce distinct internal states for all
551 arguments in [0, 27814431486576L).
552
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000553- The socket module now supports raw packets on Linux. The socket
554 family is AF_PACKET.
555
Tim Peters9ea17ac2001-02-02 05:57:15 +0000556- test_capi.py is a start at running tests of the Python C API. The tests
557 are implemented by the new Modules/_testmodule.c.
558
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000559- A new extension module, _symtable, provides provisional access to the
560 internal symbol table used by the Python compiler. A higher-level
561 interface will be added on top of _symtable in a future release.
562
Andrew M. Kuchlingdebc3522001-02-22 15:53:21 +0000563- Removed the obsolete soundex module.
564
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000565- xml.dom.minidom now uses the standard DOM exceptions. Node supports
566 the isSameNode method; NamedNodeMap the get method.
567
568- xml.sax.expatreader supports the lexical handler property; it
569 generates comment, startCDATA, and endCDATA events.
570
Tim Petersee826f82001-01-31 19:39:44 +0000571Windows changes
572
573- Build procedure: the zlib project is built in a different way that
574 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000575 the zlib binary used. See PCbuild\readme.txt for details. Your old
576 zlib-related directories can be deleted; you'll need to download fresh
577 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000578
Tim Peters9ea17ac2001-02-02 05:57:15 +0000579- Build: New subproject _test for the benefit of test_capi.py (see above).
580
Tim Petersb16c56f2001-02-02 21:24:51 +0000581- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
582 interface to some Python compiler internals).
583
584- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000585 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000586
Tim Petersa3a3a032000-11-30 05:22:44 +0000587What's New in Python 2.1 alpha 1?
588=================================
589
590Core language, builtins, and interpreter
591
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000592- There is a new Unicode companion to the PyObject_Str() API
593 called PyObject_Unicode(). It behaves in the same way as the
594 former, but assures that the returned value is an Unicode object
595 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000596
Guido van Rossumf98eda02001-01-17 15:54:45 +0000597- The comparison operators support "rich comparison overloading" (PEP
598 207). C extension types can provide a rich comparison function in
599 the new tp_richcompare slot in the type object. The cmp() function
600 and the C function PyObject_Compare() first try the new rich
601 comparison operators before trying the old 3-way comparison. There
602 is also a new C API PyObject_RichCompare() (which also falls back on
603 the old 3-way comparison, but does not constrain the outcome of the
604 rich comparison to a Boolean result).
605
606 The rich comparison function takes two objects (at least one of
607 which is guaranteed to have the type that provided the function) and
608 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
609 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
610 object, which may be NotImplemented (in which case the tp_compare
611 slot function is used as a fallback, if defined).
612
613 Classes can overload individual comparison operators by defining one
614 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000615 __ge__. There are no explicit "reflected argument" versions of
616 these; instead, __lt__ and __gt__ are each other's reflection,
617 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
618 reflection (similar at the C level). No other implications are
619 made; in particular, Python does not assume that == is the Boolean
620 inverse of !=, or that < is the Boolean inverse of >=. This makes
621 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000622
623 Classes or types that want to implement (in)equality tests but not
624 the ordering operators (i.e. unordered types) should implement ==
625 and !=, and raise an error for the ordering operators.
626
Guido van Rossuma88479f2001-01-18 14:28:08 +0000627 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +0000628 Boolean; e.g. a matrix type might want to return a matrix of bits
629 for A < B, giving elementwise comparisons. Such types should ensure
630 that any interpretation of their value in a Boolean context raises
631 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
632 at the C level) to always raise an exception.
633
Guido van Rossuma88479f2001-01-18 14:28:08 +0000634- Complex numbers use rich comparisons to define == and != but raise
635 an exception for <, <=, > and >=. Unfortunately, this also means
636 that cmp() of two complex numbers raises an exception when the two
637 numbers differ. Since it is not mathematically meaningful to compare
638 complex numbers except for equality, I hope that this doesn't break
639 too much code.
640
Tim Peters3389f192001-02-18 08:48:49 +0000641- The outcome of comparing non-numeric objects of different types is
Tim Peters14495852001-02-18 08:28:33 +0000642 not defined by the language, other than that it's arbitrary but
643 consistent (see the Reference Manual). An implementation detail changed
644 in 2.1a1 such that None now compares less than any other object. Code
645 relying on this new behavior (like code that relied on the previous
646 behavior) does so at its own risk.
647
Barry Warsaw573b5412001-01-15 20:43:18 +0000648- Functions and methods now support getting and setting arbitrarily
649 named attributes (PEP 232). Functions have a new __dict__
650 (a.k.a. func_dict) which hold the function attributes. Methods get
651 and set attributes on their underlying im_func. It is a TypeError
652 to set an attribute on a bound method.
653
Guido van Rossum051e3352001-01-15 19:11:10 +0000654- The xrange() object implementation has been improved so that
655 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
656 limitation that in this case len(xrange(sys.maxint)) can't be
657 calculated, but the common idiom "for i in xrange(sys.maxint)" will
658 work fine as long as the index i doesn't actually reach 2**31.
659 (Python uses regular ints for sequence and string indices; fixing
660 that is much more work.)
661
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000662- Two changes to from...import:
663
Guido van Rossumba381232001-02-03 15:06:40 +0000664 1) "from M import X" now works even if (after loading module M)
665 sys.modules['M'] is not a real module; it's basically a getattr()
666 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000667
668 2) "from M import *" now looks for M.__all__ to decide which names to
669 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
670 filters out names starting with '_' as before. Whether or not
671 __all__ exists, there's no restriction on the type of M.
672
Guido van Rossumf61f1662001-01-10 20:13:55 +0000673- File objects have a new method, xreadlines(). This is the fastest
674 way to iterate over all lines in a file:
675
676 for line in file.xreadlines():
677 ...do something to line...
678
679 See the xreadlines module (mentioned below) for how to do this for
680 other file-like objects.
681
682- Even if you don't use file.xreadlines(), you may expect a speedup on
683 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +0000684 quite a bit in platform-specific ways: on systems (like Linux) that
685 support flockfile(), getc_unlocked(), and funlockfile(), those are
686 used by default. On systems (like Windows) without getc_unlocked(),
687 a complicated (but still thread-safe) method using fgets() is used by
688 default.
689
Tim Petersd52269b2001-01-25 06:23:18 +0000690 You can force use of the fgets() method by #define'ing
691 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +0000692 getc_unlocked()).
693
Tim Petersd52269b2001-01-25 06:23:18 +0000694 You can force fgets() not to be used by #define'ing
695 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +0000696 test_bufio.py fails -- and let us know if it does!).
697
698- In addition, the fileinput module, while still slower than the other
699 methods on most platforms, has been sped up too, by using
700 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000701
702- Support for run-time warnings has been added, including a new
703 command line option (-W) to specify the disposition of warnings.
704 See the description of the warnings module below.
705
706- Extensive changes have been made to the coercion code. This mostly
707 affects extension modules (which can now implement mixed-type
708 numerical operators without having to use coercion), but
709 occasionally, in boundary cases the coercion semantics have changed
710 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000711 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000712 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000713 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000714
Guido van Rossumf98eda02001-01-17 15:54:45 +0000715- In connection with the coercion changes, a new built-in singleton
716 object, NotImplemented is defined. This can be returned for
717 operations that wish to indicate they are not implemented for a
718 particular combination of arguments. From C, this is
719 Py_NotImplemented.
720
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000721- The interpreter accepts now bytecode files on the command line even
722 if they do not have a .pyc or .pyo extension. On Linux, after executing
723
Martin v. Löwise214baa2001-02-04 22:37:56 +0000724import imp,sys,string
725magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
726reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
727open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000728
729 any byte code file can be used as an executable (i.e. as an argument
730 to execve(2)).
731
Tim Peters9940b802000-12-01 07:59:35 +0000732- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000733 character. In 1.6 and earlier, they never produced a sign,
734 and raised an error if the value of the long was too large
735 to fit in a Python int. In 2.0, they produced a sign if and
736 only if too large to fit in an int. This was inconsistent
737 across platforms (because the size of an int varies across
738 platforms), and inconsistent with hex() and oct(). Example:
739
740 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000741 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000742 'ffffffbe' # in 2.0 and before, on 32-bit machines
743 >>> hex(-0x42L)
744 '-0x42L' # in all versions of Python
745
Tim Peters9940b802000-12-01 07:59:35 +0000746 The behavior of %d formats for negative Python longs remains
747 the same as in 2.0 (although in 1.6 and before, they raised
748 an error if the long didn't fit in a Python int).
749
750 %u formats don't make sense for Python longs, but are allowed
751 and treated the same as %d in 2.1. In 2.0, a negative long
752 formatted via %u produced a sign if and only if too large to
753 fit in an int. In 1.6 and earlier, a negative long formatted
754 via %u raised an error if it was too big to fit in an int.
755
Guido van Rossum3661d392000-12-12 22:10:31 +0000756- Dictionary objects have an odd new method, popitem(). This removes
757 an arbitrary item from the dictionary and returns it (in the form of
758 a (key, value) pair). This can be useful for algorithms that use a
759 dictionary as a bag of "to do" items and repeatedly need to pick one
760 item. Such algorithms normally end up running in quadratic time;
761 using popitem() they can usually be made to run in linear time.
762
Tim Peters36cdad12000-12-29 02:06:45 +0000763Standard library
764
Thomas Woutersfe385252001-01-19 23:16:56 +0000765- In the time module, the time argument to the functions strftime,
766 localtime, gmtime, asctime and ctime is now optional, defaulting to
767 the current time (in the local timezone).
768
Guido van Rossumda91f222001-01-15 16:36:08 +0000769- The ftplib module now defaults to passive mode, which is deemed a
770 more useful default given that clients are often inside firewalls
771 these days. Note that this could break if ftplib is used to connect
772 to a *server* that is inside a firewall, from outside; this is
773 expected to be a very rare situation. To fix that, you can call
774 ftp.set_pasv(0).
775
Martin v. Löwis10a27872001-01-13 09:54:41 +0000776- The module site now treats .pth files not only for path configuration,
777 but also supports extensions to the initialization code: Lines starting
778 with import are executed.
779
Guido van Rossumf61f1662001-01-10 20:13:55 +0000780- There's a new module, warnings, which implements a mechanism for
781 issuing and filtering warnings. There are some new built-in
782 exceptions that serve as warning categories, and a new command line
783 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
784 turns warnings into errors). warnings.warn(message[, category])
785 issues a warning message; this can also be called from C as
786 PyErr_Warn(category, message).
787
788- A new module xreadlines was added. This exports a single factory
789 function, xreadlines(). The intention is that this code is the
790 absolutely fastest way to iterate over all lines in an open
791 file(-like) object:
792
793 import xreadlines
794 for line in xreadlines.xreadlines(file):
795 ...do something to line...
796
797 This is equivalent to the previous the speed record holder using
798 file.readlines(sizehint). Note that if file is a real file object
799 (as opposed to a file-like object), this is equivalent:
800
801 for line in file.xreadlines():
802 ...do something to line...
803
Tim Peters36cdad12000-12-29 02:06:45 +0000804- The bisect module has new functions bisect_left, insort_left,
805 bisect_right and insort_right. The old names bisect and insort
806 are now aliases for bisect_right and insort_right. XXX_right
807 and XXX_left methods differ in what happens when the new element
808 compares equal to one or more elements already in the list: the
809 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000810 right. Code that doesn't care where equal elements end up should
811 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000812
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000813- The new curses.panel module wraps the panel library that forms part
814 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
815
Guido van Rossumf61f1662001-01-10 20:13:55 +0000816- The SocketServer module now sets the allow_reuse_address flag by
817 default in the TCPServer class.
818
819- A new function, sys._getframe(), returns the stack frame pointer of
820 the caller. This is intended only as a building block for
821 higher-level mechanisms such as string interpolation.
822
Martin v. Löwis2a5130e2001-02-27 04:21:58 +0000823- The pyexpat module supports a number of new handlers, which are
824 available only in expat 1.2. If invocation of a callback fails, it
825 will report an additional frame in the traceback. Parser objects
826 participate now in garbage collection. If expat reports an unknown
827 encoding, pyexpat will try to use a Python codec; that works only
828 for single-byte charsets. The parser type objects is exposed as
829 XMLParserObject.
830
831- xml.dom now offers standard definitions for symbolic node type and
832 exception code constants, and a hierarchy of DOM exceptions. minidom
833 was adjusted to use them.
834
835- The conformance of xml.dom.minidom to the DOM specification was
836 improved. It detects a number of additional error cases; the
837 previous/next relationship works even when the tree is modified;
838 Node supports the normalize() method; NamedNodeMap, DocumentType and
839 DOMImplementation classes were added; Element supports the
840 hasAttribute and hasAttributeNS methods; and Text supports the splitText
841 method.
842
Guido van Rossumf61f1662001-01-10 20:13:55 +0000843Build issues
844
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000845- For Unix (and Unix-compatible) builds, configuration and building of
846 extension modules is now greatly automated. Rather than having to
847 edit the Modules/Setup file to indicate which modules should be
848 built and where their include files and libraries are, a
849 distutils-based setup.py script now takes care of building most
850 extension modules. All extension modules built this way are built
851 as shared libraries. Only a few modules that must be linked
852 statically are still listed in the Setup file; you won't need to
853 edit their configuration.
854
855- Python should now build out of the box on Cygwin. If it doesn't,
856 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000857
858- Python now always uses its own (renamed) implementation of getopt()
859 -- there's too much variation among C library getopt()
860 implementations.
861
862- C++ compilers are better supported; the CXX macro is always set to a
863 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000864
Tim Petersd92dfe02000-12-12 01:18:41 +0000865Windows changes
866
867- select module: By default under Windows, a select() call
868 can specify no more than 64 sockets. Python now boosts
869 this Microsoft default to 512. If you need even more than
870 that, see the MS docs (you'll need to #define FD_SETSIZE
871 and recompile Python from source).
872
Guido van Rossumf61f1662001-01-10 20:13:55 +0000873- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
874 subdirectory is no more!
875
Tim Petersa3a3a032000-11-30 05:22:44 +0000876
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000877What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000878=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000879
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000880Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000881changes are in the file HISTORY. If you are making the jump directly
882from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
883HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000884
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000885Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
886the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
887http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000888
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000889--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000890
891======================================================================
892
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000893What's new in 2.0 (since release candidate 1)?
894==============================================
895
896Standard library
897
898- The copy_reg module was modified to clarify its intended use: to
899 register pickle support for extension types, not for classes.
900 pickle() will raise a TypeError if it is passed a class.
901
902- Fixed a bug in gettext's "normalize and expand" code that prevented
903 it from finding an existing .mo file.
904
905- Restored support for HTTP/0.9 servers in httplib.
906
Tim Peters989b7b92000-10-16 20:24:53 +0000907- The math module was changed to stop raising OverflowError in case of
908 underflow, and return 0 instead in underflow cases. Whether Python
909 used to raise OverflowError in case of underflow was platform-
910 dependent (it did when the platform math library set errno to ERANGE
911 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000912
913- Fixed a bug in StringIO that occurred when the file position was not
914 at the end of the file and write() was called with enough data to
915 extend past the end of the file.
916
917- Fixed a bug that caused Tkinter error messages to get lost on
918 Windows. The bug was fixed by replacing direct use of
919 interp->result with Tcl_GetStringResult(interp).
920
921- Fixed bug in urllib2 that caused it to fail when it received an HTTP
922 redirect response.
923
924- Several changes were made to distutils: Some debugging code was
925 removed from util. Fixed the installer used when an external zip
926 program (like WinZip) is not found; the source code for this
927 installer is in Misc/distutils. check_lib() was modified to behave
928 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
929 test for whether installed modules are on sys.path was changed to
930 use both normcase() and normpath().
931
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000932- Several minor bugs were fixed in the xml package (the minidom,
933 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000934
935- The regression test driver (regrtest.py) behavior when invoked with
936 -l changed: It now reports a count of objects that are recognized as
937 garbage but not freed by the garbage collector.
938
Tim Peters989b7b92000-10-16 20:24:53 +0000939- The regression test for the math module was changed to test
940 exceptional behavior when the test is run in verbose mode. Python
941 cannot yet guarantee consistent exception behavior across platforms,
942 so the exception part of test_math is run only in verbose mode, and
943 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000944
945Internals
946
947- PyOS_CheckStack() has been disabled on Win64, where it caused
948 test_sre to fail.
949
950Build issues
951
952- Changed compiler flags, so that gcc is always invoked with -Wall and
953 -Wstrict-prototypes. Users compiling Python with GCC should see
954 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000955 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000956 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000957
Tim Petersa3a3a032000-11-30 05:22:44 +0000958- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000959
960Tools and other miscellany
961
962- The compiler in Tools/compiler was updated to support the new
963 language features introduced in 2.0: extended print statement, list
964 comprehensions, and augmented assignments. The new compiler should
965 also be backwards compatible with Python 1.5.2; the compiler will
966 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000967 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000968
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000969What's new in 2.0 release candidate 1 (since beta 2)?
970=====================================================
971
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000972What is release candidate 1?
973
974We believe that release candidate 1 will fix all known bugs that we
975intend to fix for the 2.0 final release. This release should be a bit
976more stable than the previous betas. We would like to see even more
977widespread testing before the final release, so we are producing this
978release candidate. The final release will be exactly the same unless
979any show-stopping (or brown bag) bugs are found by testers of the
980release candidate.
981
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000982All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000983to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000984
985Core language, builtins, and interpreter
986
987- A bug that caused crashes when __coerce__ was used with augmented
988 assignment, e.g. +=, was fixed.
989
990- Raise ZeroDivisionError when raising zero to a negative number,
991 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
992 power operator and the result of math.pow(0.0, -2.0) will vary by
993 platform. On Linux, it raises a ValueError.
994
995- A bug in Unicode string interpolation was fixed that occasionally
996 caused errors with formats including "%%". For example, the
997 following expression "%% %s" % u"abc" no longer raises a TypeError.
998
999- Compilation of deeply nested expressions raises MemoryError instead
1000 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
1001
1002- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
1003 rendering them useless. They are now written in binary mode again.
1004
1005Standard library
1006
1007- Keyword arguments are now accepted for most pattern and match object
1008 methods in SRE, the standard regular expression engine.
1009
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001010- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +00001011 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001012
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001013- Several bugs in the Unicode handling and error handling in _tkinter
1014 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001015
1016- Fix memory management errors in Merge() and Tkapp_Call() routines.
1017
1018- Several changes were made to cStringIO to make it compatible with
1019 the file-like object interface and with StringIO. If operations are
1020 performed on a closed object, an exception is raised. The truncate
1021 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +00001022 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001023
1024- There were many changes made to the linuxaudiodev module and its
1025 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +00001026 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001027
1028 Note that this module is named poorly, because it should work
1029 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +00001030 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001031
1032 The module now raises exceptions when errors occur instead of
1033 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
1034 audio) and defines a getptr() method that calls the
1035 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
1036
1037- The library_version attribute, introduced in an earlier beta, was
1038 removed because it can not be supported with early versions of the C
1039 readline library, which provides no way to determine the version at
1040 compile-time.
1041
1042- The binascii module is now enabled on Win64.
1043
Tim Peters46446d62000-10-09 21:19:31 +00001044- tokenize.py no longer suffers "recursion depth" errors when parsing
1045 programs with very long string literals.
1046
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001047Internals
1048
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001049- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001050 which is called when the interpreter starts up to determine where
1051 the standard library is installed. These vulnerabilities affect all
1052 previous versions of Python and can be exploited by setting very
1053 long values for PYTHONHOME or argv[0]. The risk is greatest for a
1054 setuid Python script, although use of the wrapper in
1055 Misc/setuid-prog.c will eliminate the vulnerability.
1056
1057- Fixed garbage collection bugs in instance creation that were
1058 triggered when errors occurred during initialization. The solution,
1059 applied in cPickle and in PyInstance_New(), is to call
1060 PyObject_GC_Init() after the initialization of the object's
1061 container attributes is complete.
1062
1063- pyexpat adds definitions of PyModule_AddStringConstant and
1064 PyModule_AddObject if the Python version is less than 2.0, which
1065 provides compatibility with PyXML on Python 1.5.2.
1066
1067- If the platform has a bogus definition for LONG_BIT (the number of
1068 bits in a long), an error will be reported at compile time.
1069
1070- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
1071 collection crashes and possibly other, unreported crashes.
1072
1073- Fixed a memory leak in _PyUnicode_Fini().
1074
1075Build issues
1076
1077- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001078 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +00001079 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001080
1081- The mmap.PAGESIZE constant is now initialized using sysconf when
1082 possible, which eliminates a dependency on -lucb for Reliant UNIX.
1083
1084- The md5 file should now compile on all platforms.
1085
1086- The select module now compiles on platforms that do not define
1087 POLLRDNORM and related constants.
1088
1089- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +00001090 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001091
Jeremy Hylton10921202000-10-09 18:34:12 +00001092- BeOS: A number of changes were made to the build and installation
1093 process. ar-fake now operates on a directory of object files.
1094 dl_export.h is gone, and its macros now appear on the mwcc command
1095 line during build on PPC BeOS.
1096
Jeremy Hyltond6e20232000-10-16 20:08:38 +00001097- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +00001098 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +00001099
1100- Cygwin: Support for shared libraries, Tkinter, and sockets.
1101
1102- SunOS 4.1.4_JL: Fix test for directory existence in configure.
1103
1104Tools and other miscellany
1105
1106- Removed debugging prints from main used with freeze.
1107
Tim Peters46446d62000-10-09 21:19:31 +00001108- IDLE auto-indent no longer crashes when it encounters Unicode
1109 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001110
1111What's new in 2.0 beta 2 (since beta 1)?
1112========================================
1113
1114Core language, builtins, and interpreter
1115
Tim Peters482c0212000-09-26 06:33:09 +00001116- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001117 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001118
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001119- Add -h and -V command line options to print the usage message and
1120 Python version number and exit immediately.
1121
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001122- eval() and exec accept Unicode objects as code parameters.
1123
1124- getattr() and setattr() now also accept Unicode objects for the
1125 attribute name, which are converted to strings using the default
1126 encoding before lookup.
1127
1128- Multiplication on string and Unicode now does proper bounds
1129 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
1130 string is too long."
1131
1132- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +00001133 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001134
Jeremy Hylton1b618592000-09-26 05:32:36 +00001135
1136Standard library and extensions
1137
Guido van Rossum5b08f132001-04-16 02:05:23 +00001138- socket module: the OpenSSL code now adds support for RAND_status()
1139 and EGD (Entropy Gathering Device).
1140
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001141- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +00001142 argument checking; it still takes no arguments.
1143
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001144- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001145
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001146- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001147
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001148- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001149
1150- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001151 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001152
1153- copy: Copy Unicode objects atomically.
1154
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001155- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001156
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001157- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001158
Fred Drake67233bc2000-09-26 16:40:27 +00001159- dbm: Add get() and setdefault() methods to dbm object. Add constant
1160 `library' to module that names the library used. Added doc strings
1161 and method names to error messages. Uses configure to determine
1162 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
1163 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001164
1165- distutils: Update to version 0.9.3.
1166
1167- dl: Add several dl.RTLD_ constants.
1168
1169- fpectl: Now supported on FreeBSD.
1170
1171- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
1172 found by the collector will be saved in gc.garbage. This is useful
1173 for debugging a program that creates reference cycles.
1174
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001175- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +00001176 of HTTP class. Do not close socket on zero-length response. Do not
1177 crash when server sends invalid content-length header.
1178
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001179- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001180
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001181- marshal: When reading a short, sign-extend on platforms where shorts
1182 are bigger than 16 bits. When reading a long, repair the unportable
1183 sign extension that was being done for 64-bit machines. (It assumed
1184 that signed right shift sign-extends.)
1185
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001186- operator: Add contains(), invert(), __invert__() as aliases for
1187 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001188
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001189- os: Add support for popen2() and popen3() on all platforms where
1190 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001191
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001192- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +00001193 clicking on a file in Explorer (or passing the file name to the
1194 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001195
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001196- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +00001197 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +00001198
1199- pickle: Now raises ValueError when an invalid pickle that contains
1200 a non-string repr where a string repr was expected. This behavior
1201 matches cPickle.
1202
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001203- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001204
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001205- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001206
1207- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001208 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001209 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +00001210
1211- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001212 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001213
1214- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +00001215 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +00001216 few cycles during startup since the first call to
1217 setdefaultencoding() will initialize the codec registry and the
1218 encodings package.
1219
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001220- socket: Support for size hint in readlines() method of object returned
1221 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001222
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001223- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +00001224 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +00001225 is followed by whitespace.
1226
Tim Petersa3a3a032000-11-30 05:22:44 +00001227- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001228
1229- struct: Check ranges for bytes and shorts.
1230
1231- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001232 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001233
1234- Tkinter: Image objects are now guaranteed to have unique ids. Set
1235 event.delta to zero if Tk version doesn't support mousewheel.
1236 Removed some debugging prints.
1237
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001238- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +00001239
Fred Drake67233bc2000-09-26 16:40:27 +00001240- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001241 which works around a bug in Norton AntiVirus 2000 that leads directly
1242 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001243
1244- xml: New version detection code allows PyXML to override standard
1245 XML package if PyXML version is greater than 0.6.1.
1246
Fred Drake64bb3802000-09-26 16:21:35 +00001247- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
1248 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
1249 tree only for nodes which are sufficiently interesting to a specific
1250 application. Does not provide the HTML-specific extensions. Still
1251 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001252
Fred Drake64bb3802000-09-26 16:21:35 +00001253- xml.sax: SAX 2 support for Python, including all the handler
1254 interfaces needed to process XML 1.0 compliant XML. Some
1255 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001256
Fred Drake64bb3802000-09-26 16:21:35 +00001257- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
1258 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001259
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001260
Jeremy Hylton1b618592000-09-26 05:32:36 +00001261C API
1262
1263- Add three new convenience functions for module initialization --
1264 PyModule_AddObject(), PyModule_AddIntConstant(), and
1265 PyModule_AddStringConstant().
1266
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001267- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +00001268 removed and add #error to Python.h if NULL isn't defined after
1269 #include of stdio.h.
1270
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001271- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +00001272 backwards compatibility (at the source level) with old extensions.
1273
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001274- A wrapper API was added for signal() and sigaction(). Instead of
1275 either function, always use PyOS_getsig() to get a signal handler
1276 and PyOS_setsig() to set one. A new convenience typedef
1277 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001278
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001279- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +00001280 internal data buffer and size of a string object -- or the default
1281 encoded version of a Unicode object.
1282
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001283- PyString_Size() and PyString_AsString() accept Unicode objects.
1284
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001285- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +00001286 exists). INT_MAX and LONG_MAX will always be defined, even if
1287 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001288
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001289- PyFloat_FromString takes a second argument, pend, that was
1290 effectively useless. It is now officially useless but preserved for
1291 backwards compatibility. If the pend argument is not NULL, *pend is
1292 set to NULL.
1293
1294- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
1295 for the attribute name. See note on getattr() above.
1296
1297- A few bug fixes to argument processing for Unicode.
1298 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
1299 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
1300 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +00001301 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001302
1303- Py_BuildValue accepts B format (for bgen-generated code).
1304
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001305
Jeremy Hylton1b618592000-09-26 05:32:36 +00001306Internals
1307
1308- On Unix, fix code for finding Python installation directory so that
1309 it works when argv[0] is a relative path.
1310
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +00001311- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001312 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +00001313 rather than by generating a copy of the object.
1314
Tim Peters482c0212000-09-26 06:33:09 +00001315- Several of the internal Unicode tables are much smaller now, and
1316 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001317
Jeremy Hylton97693b02000-09-26 17:42:51 +00001318- In the garbage collector: Fixed bug in collection of tuples. Fixed
1319 bug that caused some instances to be removed from the container set
1320 while they were still live. Fixed parsing in gc.set_debug() for
1321 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001322
1323- Fixed refcount problem in instance deallocation that only occurred
1324 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
1325
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001326- On Windows, getpythonregpath is now protected against null data in
1327 registry key.
1328
1329- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +00001330 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001331
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001332
Jeremy Hylton1b618592000-09-26 05:32:36 +00001333Build and platform-specific issues
1334
1335- Better support of GNU Pth via --with-pth configure option.
1336
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001337- Python/C API now properly exposed to dynamically-loaded extension
1338 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +00001339
1340- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
1341 Don't define MS_SYNC to be zero when it is undefined. Added missing
1342 prototypes in posixmodule.c.
1343
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001344- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001345 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +00001346
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001347- Fix largefile support on older NetBSD systems and OpenBSD by adding
1348 define for TELL64.
1349
1350
1351Tools and other miscellany
1352
1353- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
1354
1355- freeze: The modulefinder now works with 2.0 opcodes.
1356
Tim Petersa3a3a032000-11-30 05:22:44 +00001357- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +00001358 Move hackery of sys.argv until after the Tk instance has been
1359 created, which allows the application-specific Tkinter
1360 initialization to be executed if present; also pass an explicit
1361 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +00001362
Jeremy Hylton1b618592000-09-26 05:32:36 +00001363
1364What's new in 2.0 beta 1?
1365=========================
1366
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001367Source Incompatibilities
1368------------------------
1369
1370None. Note that 1.6 introduced several incompatibilities with 1.5.2,
1371such as single-argument append(), connect() and bind(), and changes to
1372str(long) and repr(float).
1373
1374
1375Binary Incompatibilities
1376------------------------
1377
1378- Third party extensions built for Python 1.5.x or 1.6 cannot be used
1379with Python 2.0; these extensions will have to be rebuilt for Python
13802.0.
1381
1382- On Windows, attempting to import a third party extension built for
1383Python 1.5.x or 1.6 results in an immediate crash; there's not much we
1384can do about this. Check your PYTHONPATH environment variable!
1385
1386- Python bytecode files (*.pyc and *.pyo) are not compatible between
1387releases.
1388
1389
1390Overview of Changes Since 1.6
1391-----------------------------
1392
1393There are many new modules (including brand new XML support through
1394the xml package, and i18n support through the gettext module); a list
1395of all new modules is included below. Lots of bugs have been fixed.
1396
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001397The process for making major new changes to the language has changed
1398since Python 1.6. Enhancements must now be documented by a Python
1399Enhancement Proposal (PEP) before they can be accepted.
1400
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001401There are several important syntax enhancements, described in more
1402detail below:
1403
1404 - Augmented assignment, e.g. x += 1
1405
1406 - List comprehensions, e.g. [x**2 for x in range(10)]
1407
1408 - Extended import statement, e.g. import Module as Name
1409
1410 - Extended print statement, e.g. print >> file, "Hello"
1411
1412Other important changes:
1413
1414 - Optional collection of cyclical garbage
1415
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001416Python Enhancement Proposal (PEP)
1417---------------------------------
1418
1419PEP stands for Python Enhancement Proposal. A PEP is a design
1420document providing information to the Python community, or describing
1421a new feature for Python. The PEP should provide a concise technical
1422specification of the feature and a rationale for the feature.
1423
1424We intend PEPs to be the primary mechanisms for proposing new
1425features, for collecting community input on an issue, and for
1426documenting the design decisions that have gone into Python. The PEP
1427author is responsible for building consensus within the community and
1428documenting dissenting opinions.
1429
1430The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001431
1432Augmented Assignment
1433--------------------
1434
1435This must have been the most-requested feature of the past years!
1436Eleven new assignment operators were added:
1437
Guido van Rossume905e952000-09-05 12:42:46 +00001438 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001439
1440For example,
1441
1442 A += B
1443
1444is similar to
1445
1446 A = A + B
1447
1448except that A is evaluated only once (relevant when A is something
1449like dict[index].attr).
1450
1451However, if A is a mutable object, A may be modified in place. Thus,
1452if A is a number or a string, A += B has the same effect as A = A+B
1453(except A is only evaluated once); but if a is a list, A += B has the
1454same effect as A.extend(B)!
1455
1456Classes and built-in object types can override the new operators in
1457order to implement the in-place behavior; the not-in-place behavior is
1458used automatically as a fallback when an object doesn't implement the
1459in-place behavior. For classes, the method name is derived from the
1460method name for the corresponding not-in-place operator by inserting
1461an 'i' in front of the name, e.g. __iadd__ implements in-place
1462__add__.
1463
1464Augmented assignment was implemented by Thomas Wouters.
1465
1466
1467List Comprehensions
1468-------------------
1469
1470This is a flexible new notation for lists whose elements are computed
1471from another list (or lists). The simplest form is:
1472
1473 [<expression> for <variable> in <sequence>]
1474
Guido van Rossum56db0952000-09-06 23:34:25 +00001475For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001476This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001477
1478You can also add a condition:
1479
1480 [<expression> for <variable> in <sequence> if <condition>]
1481
1482For example, [w for w in words if w == w.lower()] would yield the list
1483of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001484than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001485
1486You can also have nested for loops and more than one 'if' clause. For
1487example, here's a function that flattens a sequence of sequences::
1488
1489 def flatten(seq):
1490 return [x for subseq in seq for x in subseq]
1491
1492 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1493
1494This prints
1495
1496 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1497
1498List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001499Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001500
1501
1502Extended Import Statement
1503-------------------------
1504
1505Many people have asked for a way to import a module under a different
1506name. This can be accomplished like this:
1507
1508 import foo
1509 bar = foo
1510 del foo
1511
1512but this common idiom gets old quickly. A simple extension of the
1513import statement now allows this to be written as follows:
1514
1515 import foo as bar
1516
1517There's also a variant for 'from ... import':
1518
1519 from foo import bar as spam
1520
1521This also works with packages; e.g. you can write this:
1522
1523 import test.regrtest as regrtest
1524
1525Note that 'as' is not a new keyword -- it is recognized only in this
1526context (this is only possible because the syntax for the import
1527statement doesn't involve expressions).
1528
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001529Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001530
1531
1532Extended Print Statement
1533------------------------
1534
1535Easily the most controversial new feature, this extension to the print
1536statement adds an option to make the output go to a different file
1537than the default sys.stdout.
1538
1539For example, to write an error message to sys.stderr, you can now
1540write:
1541
1542 print >> sys.stderr, "Error: bad dog!"
1543
1544As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001545evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001546
1547 print >> None, "Hello world"
1548
1549is equivalent to
1550
1551 print "Hello world"
1552
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001553Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001554
1555
1556Optional Collection of Cyclical Garbage
1557---------------------------------------
1558
1559Python is now equipped with a garbage collector that can hunt down
1560cyclical references between Python objects. It's no replacement for
1561reference counting; in fact, it depends on the reference counts being
1562correct, and decides that a set of objects belong to a cycle if all
1563their reference counts can be accounted for from their references to
1564each other. This devious scheme was first proposed by Eric Tiedemann,
1565and brought to implementation by Neil Schemenauer.
1566
1567There's a module "gc" that lets you control some parameters of the
1568garbage collection. There's also an option to the configure script
1569that lets you enable or disable the garbage collection. In 2.0b1,
1570it's on by default, so that we (hopefully) can collect decent user
1571experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001572performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001573off by default in the final 2.0 release.
1574
1575
1576Smaller Changes
1577---------------
1578
1579A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1580map(None, seq1, seq2, ...) when the sequences have the same length;
1581i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1582the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001583zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001584
1585sys.version_info is a tuple (major, minor, micro, level, serial).
1586
1587Dictionaries have an odd new method, setdefault(key, default).
1588dict.setdefault(key, default) returns dict[key] if it exists; if not,
1589it sets dict[key] to default and returns that value. Thus:
1590
1591 dict.setdefault(key, []).append(item)
1592
1593does the same work as this common idiom:
1594
1595 if not dict.has_key(key):
1596 dict[key] = []
1597 dict[key].append(item)
1598
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001599There are two new variants of SyntaxError that are raised for
1600indentation-related errors: IndentationError and TabError.
1601
1602Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1603escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001604
1605The limits on the size of expressions and file in Python source code
1606have been raised from 2**16 to 2**32. Previous versions of Python
1607were limited because the maximum argument size the Python VM accepted
1608was 2**16. This limited the size of object constructor expressions,
1609e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1610limit was raised thanks to a patch by Charles Waldman that effectively
1611fixes the problem. It is now much more likely that you will be
1612limited by available memory than by an arbitrary limit in Python.
1613
1614The interpreter's maximum recursion depth can be modified by Python
1615programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1616limit is the maximum number of recursive calls that can be made by
1617Python code. The limit exists to prevent infinite recursion from
1618overflowing the C stack and causing a core dump. The default value is
16191000. The maximum safe value for a particular platform can be found
1620by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001621
1622New Modules and Packages
1623------------------------
1624
1625atexit - for registering functions to be called when Python exits.
1626
1627imputil - Greg Stein's alternative API for writing custom import
1628hooks.
1629
1630pyexpat - an interface to the Expat XML parser, contributed by Paul
1631Prescod.
1632
1633xml - a new package with XML support code organized (so far) in three
1634subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1635would fill a volume. There's a special feature whereby a
1636user-installed package named _xmlplus overrides the standard
1637xmlpackage; this is intended to give the XML SIG a hook to distribute
1638backwards-compatible updates to the standard xml package.
1639
1640webbrowser - a platform-independent API to launch a web browser.
1641
1642
Guido van Rossume905e952000-09-05 12:42:46 +00001643Changed Modules
1644---------------
1645
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001646array -- new methods for array objects: count, extend, index, pop, and
1647remove
1648
1649binascii -- new functions b2a_hex and a2b_hex that convert between
1650binary data and its hex representation
1651
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001652calendar -- Many new functions that support features including control
1653over which day of the week is the first day, returning strings instead
1654of printing them. Also new symbolic constants for days of week,
1655e.g. MONDAY, ..., SUNDAY.
1656
1657cgi -- FieldStorage objects have a getvalue method that works like a
1658dictionary's get method and returns the value attribute of the object.
1659
1660ConfigParser -- The parser object has new methods has_option,
1661remove_section, remove_option, set, and write. They allow the module
1662to be used for writing config files as well as reading them.
1663
1664ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001665optionally support the RFC 959 REST command.
1666
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001667gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001668
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001669httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1670the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001671
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001672locale -- implement getdefaultlocale for Win32 and Macintosh
1673
1674marshal -- no longer dumps core when marshaling deeply nested or
1675recursive data structures
1676
1677os -- new functions isatty, seteuid, setegid, setreuid, setregid
1678
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001679os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1680support under Unix.
1681
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001682os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001683
1684os.path -- fix semantics of os.path.commonprefix
1685
1686smtplib -- support for sending very long messages
1687
1688socket -- new function getfqdn()
1689
1690readline -- new functions to read, write and truncate history files.
1691The readline section of the library reference manual contains an
1692example.
1693
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001694select -- add interface to poll system call
1695
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001696shutil -- new copyfileobj function
1697
1698SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1699HTTP server.
1700
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001701Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001702
1703urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001704e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001705
1706whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001707
1708
1709Obsolete Modules
1710----------------
1711
1712None. However note that 1.6 made a whole slew of modules obsolete:
1713stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1714poly, zmod, strop, util, whatsound.
1715
1716
1717Changed, New, Obsolete Tools
1718----------------------------
1719
Tim Peters8b092332000-09-05 20:15:25 +00001720None.
Guido van Rossume905e952000-09-05 12:42:46 +00001721
1722
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001723C-level Changes
1724---------------
1725
1726Several cleanup jobs were carried out throughout the source code.
1727
1728All C code was converted to ANSI C; we got rid of all uses of the
1729Py_PROTO() macro, which makes the header files a lot more readable.
1730
1731Most of the portability hacks were moved to a new header file,
1732pyport.h; several other new header files were added and some old
1733header files were removed, in an attempt to create a more rational set
1734of header files. (Few of these ever need to be included explicitly;
1735they are all included by Python.h.)
1736
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001737Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001738and Win64, especially for the new Intel Itanium processor. Mick also
1739added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001740
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001741The C APIs to return an object's size have been update to consistently
1742use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1743previous versions, the abstract interfaces used PyXXX_Length and the
1744concrete interfaces used PyXXX_Size. The old names,
1745e.g. PyObject_Length, are still available for backwards compatibility
1746at the API level, but are deprecated.
1747
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001748The PyOS_CheckStack function has been implemented on Windows by
1749Fredrik Lundh. It prevents Python from failing with a stack overflow
1750on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001751
1752The GC changes resulted in creation of two new slots on object,
1753tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001754the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001755
1756The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001757C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001758
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001759PyErr_Format has been updated to automatically calculate the size of
1760the buffer needed to hold the formatted result string. This change
1761prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001762
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001763New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001764
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001765PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1766that are the same as their non-Ex counterparts except they take an
1767extra flag argument that tells them to close the file when done.
1768
1769XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001770
Tim Peters8b092332000-09-05 20:15:25 +00001771
1772Windows Changes
1773---------------
1774
1775New popen2/popen3/peopen4 in os module (see Changed Modules above).
1776
1777os.popen is much more usable on Windows 95 and 98. See Microsoft
1778Knowledge Base article Q150956. The Win9x workaround described there
1779is implemented by the new w9xpopen.exe helper in the root of your
1780Python installation. Note that Python uses this internally; it is not
1781a standalone program.
1782
1783Administrator privileges are no longer required to install Python
1784on Windows NT or Windows 2000. If you have administrator privileges,
1785Python's registry info will be written under HKEY_LOCAL_MACHINE.
1786Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001787under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001788uses of Python, but will prevent some advanced uses from working
1789(for example, running a Python script as an NT service, or possibly
1790from CGI).
1791
1792[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1793installer; instead, it installs the needed Tcl/Tk files directly in the
1794Python directory. If you already have a Tcl/Tk installation, this
1795wastes some disk space (about 4 Megs) but avoids problems with
1796conflicting Tcl/Tk installations, and makes it much easier for Python
1797to ensure that Tcl/Tk can find all its files.
1798
1799[This was new in 1.6] The Windows installer now installs by default in
1800\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1801
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001802
1803Updates to the changes between 1.5.2 and 1.6
1804--------------------------------------------
1805
1806The 1.6 NEWS file can't be changed after the release is done, so here
1807is some late-breaking news:
1808
1809New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1810and changes to getlocale() and setlocale().
1811
1812The new module is now enabled per default.
1813
1814It is not true that the encodings codecs cannot be used for normal
1815strings: the string.encode() (which is also present on 8-bit strings
1816!) allows using them for 8-bit strings too, e.g. to convert files from
1817cp1252 (Windows) to latin-1 or vice-versa.
1818
1819Japanese codecs are available from Tamito KAJIYAMA:
1820http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1821
1822
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001823======================================================================