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Tim Petersd66595f2001-02-04 03:09:53 +00001What's New in Python 2.1 alpha 507?
2===================================
3
4Core language, builtins, and interpreter
5
6Standard library
7
8Windows changes
9
10- Build: Subproject _test (effectively) renamed to _testcapi.
11
Tim Petersd7b5e882001-01-25 03:36:26 +000012What's New in Python 2.1 alpha 2?
13=================================
Tim Peters40ead762001-01-27 05:35:26 +000014
Tim Petersd7b5e882001-01-25 03:36:26 +000015Core language, builtins, and interpreter
16
Jeremy Hylton4589bd82001-02-01 20:38:45 +000017- Scopes nest. If a name is used in a function or class, but is not
18 local, the definition in the nearest enclosing function scope will
19 be used. One consequence of this change is that lambda statements
20 could reference variables in the namespaces where the lambda is
21 defined. In some unusual cases, this change will break code.
22
23 In all previous version of Python, names were resolved in exactly
24 three namespaces -- the local namespace, the global namespace, and
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +000025 the builtin namespace. According to this old definition, if a
Jeremy Hylton4589bd82001-02-01 20:38:45 +000026 function A is defined within a function B, the names bound in B are
27 not visible in A. The new rules make names bound in B visible in A,
28 unless A contains a name binding that hides the binding in B.
29
30 Section 4.1 of the reference manual describes the new scoping rules
31 in detail. The test script in Lib/test/test_scope.py demonstrates
32 some of the effects of the change.
33
34 The new rules will cause existing code to break if it defines nested
35 functions where an outer function has local variables with the same
36 name as globals or builtins used by the inner function. Example:
37
38 def munge(str):
39 def helper(x):
40 return str(x)
41 if type(str) != type(''):
42 str = helper(str)
43 return str.strip()
44
45 Under the old rules, the name str in helper() is bound to the
46 builtin function str(). Under the new rules, it will be bound to
47 the argument named str and an error will occur when helper() is
48 called.
49
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +000050- The compiler will report a SyntaxError if "from ... import *" occurs
51 in a function or class scope. The language reference has documented
52 that this case is illegal, but the compiler never checked for it.
53 The recent introduction of nested scope makes the meaning of this
54 form of name binding ambiguous. In a future release, the compiler
55 may allow this form when there is no possibility of ambiguity.
56
Tim Peters40ead762001-01-27 05:35:26 +000057- repr(string) is easier to read, now using hex escapes instead of octal,
58 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
59
60 >>> "\texample \r\n" + chr(0) + chr(255)
61 '\texample \r\n\x00\xff' # in 2.1
62 '\011example \015\012\000\377' # in 2.0
63
Moshe Zadka6af0ce02001-01-29 06:41:00 +000064- Functions are now compared and hashed by identity, not by value, since
65 the func_code attribute is writable.
66
Fred Drakefb9d7122001-02-01 20:00:40 +000067- Weak references (PEP 205) have been added. This involves a few
68 changes in the core, an extension module (_weakref), and a Python
69 module (weakref). The weakref module is the public interface. It
70 includes support for "explicit" weak references, proxy objects, and
71 mappings with weakly held values.
72
Jeremy Hylton0072d5a2001-02-01 22:53:15 +000073- A 'continue' statement can now appear in a try block within the body
74 of a loop. It is still not possible to use continue in a finally
Tim Peters9ea17ac2001-02-02 05:57:15 +000075 clause.
Jeremy Hylton0072d5a2001-02-01 22:53:15 +000076
Tim Petersd7b5e882001-01-25 03:36:26 +000077Standard library
78
Barry Warsaw30dbd142001-01-31 22:14:01 +000079- mailbox.py now has a new class, PortableUnixMailbox which is
80 identical to UnixMailbox but uses a more portable scheme for
81 determining From_ separators. Also, the constructors for all the
82 classes in this module have a new optional `factory' argument, which
83 is a callable used when new message classes must be instantiated by
84 the next() method.
85
Tim Petersd7b5e882001-01-25 03:36:26 +000086- random.py is now self-contained, and offers all the functionality of
87 the now-deprecated whrandom.py. See the docs for details. random.py
88 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +000089 and restoring the internal state of the generator; and jumpahead(n),
90 for quickly forcing the internal state to be the same as if n calls to
91 random() had been made. The latter is particularly useful for multi-
92 threaded programs, creating one instance of the random.Random() class for
93 each thread, then using .jumpahead() to force each instance to use a
94 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +000095
Tim Peters0de88fc2001-02-01 04:59:18 +000096- random.py's seed() function is new. For bit-for-bit compatibility with
97 prior releases, use the whseed function instead. The new seed function
98 addresses two problems: (1) The old function couldn't produce more than
99 about 2**24 distinct internal states; the new one about 2**45 (the best
100 that can be done in the Wichmann-Hill generator). (2) The old function
101 sometimes produced identical internal states when passed distinct
102 integers, and there was no simple way to predict when that would happen;
103 the new one guarantees to produce distinct internal states for all
104 arguments in [0, 27814431486576L).
105
Jeremy Hylton4c4fda02001-02-02 03:29:24 +0000106- The socket module now supports raw packets on Linux. The socket
107 family is AF_PACKET.
108
Tim Peters9ea17ac2001-02-02 05:57:15 +0000109- test_capi.py is a start at running tests of the Python C API. The tests
110 are implemented by the new Modules/_testmodule.c.
111
Jeremy Hyltond6b1cf92001-02-02 20:06:28 +0000112- A new extension module, _symtable, provides provisional access to the
113 internal symbol table used by the Python compiler. A higher-level
114 interface will be added on top of _symtable in a future release.
115
Tim Petersee826f82001-01-31 19:39:44 +0000116Windows changes
117
118- Build procedure: the zlib project is built in a different way that
119 ensures the zlib header files used can no longer get out of synch with
Tim Peters9ea17ac2001-02-02 05:57:15 +0000120 the zlib binary used. See PCbuild\readme.txt for details. Your old
121 zlib-related directories can be deleted; you'll need to download fresh
122 source for zlib and unpack it into a new directory.
Tim Petersee826f82001-01-31 19:39:44 +0000123
Tim Peters9ea17ac2001-02-02 05:57:15 +0000124- Build: New subproject _test for the benefit of test_capi.py (see above).
125
Tim Petersb16c56f2001-02-02 21:24:51 +0000126- Build: New subproject _symtable, for new DLL _symtable.pyd (a nascent
127 interface to some Python compiler internals).
128
129- Build: Subproject ucnhash is gone, since the code was folded into the
Tim Peters9ea17ac2001-02-02 05:57:15 +0000130 unicodedata subproject.
Tim Petersd7b5e882001-01-25 03:36:26 +0000131
Tim Petersa3a3a032000-11-30 05:22:44 +0000132What's New in Python 2.1 alpha 1?
133=================================
134
135Core language, builtins, and interpreter
136
Marc-André Lemburgebb195b2001-01-20 10:34:52 +0000137- There is a new Unicode companion to the PyObject_Str() API
138 called PyObject_Unicode(). It behaves in the same way as the
139 former, but assures that the returned value is an Unicode object
140 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +0000141
Guido van Rossumf98eda02001-01-17 15:54:45 +0000142- The comparison operators support "rich comparison overloading" (PEP
143 207). C extension types can provide a rich comparison function in
144 the new tp_richcompare slot in the type object. The cmp() function
145 and the C function PyObject_Compare() first try the new rich
146 comparison operators before trying the old 3-way comparison. There
147 is also a new C API PyObject_RichCompare() (which also falls back on
148 the old 3-way comparison, but does not constrain the outcome of the
149 rich comparison to a Boolean result).
150
151 The rich comparison function takes two objects (at least one of
152 which is guaranteed to have the type that provided the function) and
153 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
154 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
155 object, which may be NotImplemented (in which case the tp_compare
156 slot function is used as a fallback, if defined).
157
158 Classes can overload individual comparison operators by defining one
159 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +0000160 __ge__. There are no explicit "reflected argument" versions of
161 these; instead, __lt__ and __gt__ are each other's reflection,
162 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
163 reflection (similar at the C level). No other implications are
164 made; in particular, Python does not assume that == is the Boolean
165 inverse of !=, or that < is the Boolean inverse of >=. This makes
166 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +0000167
168 Classes or types that want to implement (in)equality tests but not
169 the ordering operators (i.e. unordered types) should implement ==
170 and !=, and raise an error for the ordering operators.
171
Guido van Rossuma88479f2001-01-18 14:28:08 +0000172 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +0000173 Boolean; e.g. a matrix type might want to return a matrix of bits
174 for A < B, giving elementwise comparisons. Such types should ensure
175 that any interpretation of their value in a Boolean context raises
176 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
177 at the C level) to always raise an exception.
178
Guido van Rossuma88479f2001-01-18 14:28:08 +0000179- Complex numbers use rich comparisons to define == and != but raise
180 an exception for <, <=, > and >=. Unfortunately, this also means
181 that cmp() of two complex numbers raises an exception when the two
182 numbers differ. Since it is not mathematically meaningful to compare
183 complex numbers except for equality, I hope that this doesn't break
184 too much code.
185
Barry Warsaw573b5412001-01-15 20:43:18 +0000186- Functions and methods now support getting and setting arbitrarily
187 named attributes (PEP 232). Functions have a new __dict__
188 (a.k.a. func_dict) which hold the function attributes. Methods get
189 and set attributes on their underlying im_func. It is a TypeError
190 to set an attribute on a bound method.
191
Guido van Rossum051e3352001-01-15 19:11:10 +0000192- The xrange() object implementation has been improved so that
193 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
194 limitation that in this case len(xrange(sys.maxint)) can't be
195 calculated, but the common idiom "for i in xrange(sys.maxint)" will
196 work fine as long as the index i doesn't actually reach 2**31.
197 (Python uses regular ints for sequence and string indices; fixing
198 that is much more work.)
199
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000200- Two changes to from...import:
201
Guido van Rossumba381232001-02-03 15:06:40 +0000202 1) "from M import X" now works even if (after loading module M)
203 sys.modules['M'] is not a real module; it's basically a getattr()
204 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000205
206 2) "from M import *" now looks for M.__all__ to decide which names to
207 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
208 filters out names starting with '_' as before. Whether or not
209 __all__ exists, there's no restriction on the type of M.
210
Guido van Rossumf61f1662001-01-10 20:13:55 +0000211- File objects have a new method, xreadlines(). This is the fastest
212 way to iterate over all lines in a file:
213
214 for line in file.xreadlines():
215 ...do something to line...
216
217 See the xreadlines module (mentioned below) for how to do this for
218 other file-like objects.
219
220- Even if you don't use file.xreadlines(), you may expect a speedup on
221 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +0000222 quite a bit in platform-specific ways: on systems (like Linux) that
223 support flockfile(), getc_unlocked(), and funlockfile(), those are
224 used by default. On systems (like Windows) without getc_unlocked(),
225 a complicated (but still thread-safe) method using fgets() is used by
226 default.
227
Tim Petersd52269b2001-01-25 06:23:18 +0000228 You can force use of the fgets() method by #define'ing
229 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +0000230 getc_unlocked()).
231
Tim Petersd52269b2001-01-25 06:23:18 +0000232 You can force fgets() not to be used by #define'ing
233 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +0000234 test_bufio.py fails -- and let us know if it does!).
235
236- In addition, the fileinput module, while still slower than the other
237 methods on most platforms, has been sped up too, by using
238 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000239
240- Support for run-time warnings has been added, including a new
241 command line option (-W) to specify the disposition of warnings.
242 See the description of the warnings module below.
243
244- Extensive changes have been made to the coercion code. This mostly
245 affects extension modules (which can now implement mixed-type
246 numerical operators without having to use coercion), but
247 occasionally, in boundary cases the coercion semantics have changed
248 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000249 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000250 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000251 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000252
Guido van Rossumf98eda02001-01-17 15:54:45 +0000253- In connection with the coercion changes, a new built-in singleton
254 object, NotImplemented is defined. This can be returned for
255 operations that wish to indicate they are not implemented for a
256 particular combination of arguments. From C, this is
257 Py_NotImplemented.
258
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000259- The interpreter accepts now bytecode files on the command line even
260 if they do not have a .pyc or .pyo extension. On Linux, after executing
261
262 echo ':pyc:M::\x87\xc6\x0d\x0a::/usr/local/bin/python:' > /proc/sys/fs/binfmt_misc/register
263
264 any byte code file can be used as an executable (i.e. as an argument
265 to execve(2)).
266
Tim Peters9940b802000-12-01 07:59:35 +0000267- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000268 character. In 1.6 and earlier, they never produced a sign,
269 and raised an error if the value of the long was too large
270 to fit in a Python int. In 2.0, they produced a sign if and
271 only if too large to fit in an int. This was inconsistent
272 across platforms (because the size of an int varies across
273 platforms), and inconsistent with hex() and oct(). Example:
274
275 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000276 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000277 'ffffffbe' # in 2.0 and before, on 32-bit machines
278 >>> hex(-0x42L)
279 '-0x42L' # in all versions of Python
280
Tim Peters9940b802000-12-01 07:59:35 +0000281 The behavior of %d formats for negative Python longs remains
282 the same as in 2.0 (although in 1.6 and before, they raised
283 an error if the long didn't fit in a Python int).
284
285 %u formats don't make sense for Python longs, but are allowed
286 and treated the same as %d in 2.1. In 2.0, a negative long
287 formatted via %u produced a sign if and only if too large to
288 fit in an int. In 1.6 and earlier, a negative long formatted
289 via %u raised an error if it was too big to fit in an int.
290
Guido van Rossum3661d392000-12-12 22:10:31 +0000291- Dictionary objects have an odd new method, popitem(). This removes
292 an arbitrary item from the dictionary and returns it (in the form of
293 a (key, value) pair). This can be useful for algorithms that use a
294 dictionary as a bag of "to do" items and repeatedly need to pick one
295 item. Such algorithms normally end up running in quadratic time;
296 using popitem() they can usually be made to run in linear time.
297
Tim Peters36cdad12000-12-29 02:06:45 +0000298Standard library
299
Thomas Woutersfe385252001-01-19 23:16:56 +0000300- In the time module, the time argument to the functions strftime,
301 localtime, gmtime, asctime and ctime is now optional, defaulting to
302 the current time (in the local timezone).
303
Guido van Rossumda91f222001-01-15 16:36:08 +0000304- The ftplib module now defaults to passive mode, which is deemed a
305 more useful default given that clients are often inside firewalls
306 these days. Note that this could break if ftplib is used to connect
307 to a *server* that is inside a firewall, from outside; this is
308 expected to be a very rare situation. To fix that, you can call
309 ftp.set_pasv(0).
310
Martin v. Löwis10a27872001-01-13 09:54:41 +0000311- The module site now treats .pth files not only for path configuration,
312 but also supports extensions to the initialization code: Lines starting
313 with import are executed.
314
Guido van Rossumf61f1662001-01-10 20:13:55 +0000315- There's a new module, warnings, which implements a mechanism for
316 issuing and filtering warnings. There are some new built-in
317 exceptions that serve as warning categories, and a new command line
318 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
319 turns warnings into errors). warnings.warn(message[, category])
320 issues a warning message; this can also be called from C as
321 PyErr_Warn(category, message).
322
323- A new module xreadlines was added. This exports a single factory
324 function, xreadlines(). The intention is that this code is the
325 absolutely fastest way to iterate over all lines in an open
326 file(-like) object:
327
328 import xreadlines
329 for line in xreadlines.xreadlines(file):
330 ...do something to line...
331
332 This is equivalent to the previous the speed record holder using
333 file.readlines(sizehint). Note that if file is a real file object
334 (as opposed to a file-like object), this is equivalent:
335
336 for line in file.xreadlines():
337 ...do something to line...
338
Tim Peters36cdad12000-12-29 02:06:45 +0000339- The bisect module has new functions bisect_left, insort_left,
340 bisect_right and insort_right. The old names bisect and insort
341 are now aliases for bisect_right and insort_right. XXX_right
342 and XXX_left methods differ in what happens when the new element
343 compares equal to one or more elements already in the list: the
344 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000345 right. Code that doesn't care where equal elements end up should
346 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000347
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000348- The new curses.panel module wraps the panel library that forms part
349 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
350
Guido van Rossumf61f1662001-01-10 20:13:55 +0000351- The SocketServer module now sets the allow_reuse_address flag by
352 default in the TCPServer class.
353
354- A new function, sys._getframe(), returns the stack frame pointer of
355 the caller. This is intended only as a building block for
356 higher-level mechanisms such as string interpolation.
357
358Build issues
359
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000360- For Unix (and Unix-compatible) builds, configuration and building of
361 extension modules is now greatly automated. Rather than having to
362 edit the Modules/Setup file to indicate which modules should be
363 built and where their include files and libraries are, a
364 distutils-based setup.py script now takes care of building most
365 extension modules. All extension modules built this way are built
366 as shared libraries. Only a few modules that must be linked
367 statically are still listed in the Setup file; you won't need to
368 edit their configuration.
369
370- Python should now build out of the box on Cygwin. If it doesn't,
371 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000372
373- Python now always uses its own (renamed) implementation of getopt()
374 -- there's too much variation among C library getopt()
375 implementations.
376
377- C++ compilers are better supported; the CXX macro is always set to a
378 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000379
Tim Petersd92dfe02000-12-12 01:18:41 +0000380Windows changes
381
382- select module: By default under Windows, a select() call
383 can specify no more than 64 sockets. Python now boosts
384 this Microsoft default to 512. If you need even more than
385 that, see the MS docs (you'll need to #define FD_SETSIZE
386 and recompile Python from source).
387
Guido van Rossumf61f1662001-01-10 20:13:55 +0000388- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
389 subdirectory is no more!
390
Tim Petersa3a3a032000-11-30 05:22:44 +0000391
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000392What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000393=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000394
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000395Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000396changes are in the file HISTORY. If you are making the jump directly
397from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
398HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000399
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000400Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
401the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
402http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000403
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000404--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000405
406======================================================================
407
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000408What's new in 2.0 (since release candidate 1)?
409==============================================
410
411Standard library
412
413- The copy_reg module was modified to clarify its intended use: to
414 register pickle support for extension types, not for classes.
415 pickle() will raise a TypeError if it is passed a class.
416
417- Fixed a bug in gettext's "normalize and expand" code that prevented
418 it from finding an existing .mo file.
419
420- Restored support for HTTP/0.9 servers in httplib.
421
Tim Peters989b7b92000-10-16 20:24:53 +0000422- The math module was changed to stop raising OverflowError in case of
423 underflow, and return 0 instead in underflow cases. Whether Python
424 used to raise OverflowError in case of underflow was platform-
425 dependent (it did when the platform math library set errno to ERANGE
426 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000427
428- Fixed a bug in StringIO that occurred when the file position was not
429 at the end of the file and write() was called with enough data to
430 extend past the end of the file.
431
432- Fixed a bug that caused Tkinter error messages to get lost on
433 Windows. The bug was fixed by replacing direct use of
434 interp->result with Tcl_GetStringResult(interp).
435
436- Fixed bug in urllib2 that caused it to fail when it received an HTTP
437 redirect response.
438
439- Several changes were made to distutils: Some debugging code was
440 removed from util. Fixed the installer used when an external zip
441 program (like WinZip) is not found; the source code for this
442 installer is in Misc/distutils. check_lib() was modified to behave
443 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
444 test for whether installed modules are on sys.path was changed to
445 use both normcase() and normpath().
446
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000447- Several minor bugs were fixed in the xml package (the minidom,
448 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000449
450- The regression test driver (regrtest.py) behavior when invoked with
451 -l changed: It now reports a count of objects that are recognized as
452 garbage but not freed by the garbage collector.
453
Tim Peters989b7b92000-10-16 20:24:53 +0000454- The regression test for the math module was changed to test
455 exceptional behavior when the test is run in verbose mode. Python
456 cannot yet guarantee consistent exception behavior across platforms,
457 so the exception part of test_math is run only in verbose mode, and
458 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000459
460Internals
461
462- PyOS_CheckStack() has been disabled on Win64, where it caused
463 test_sre to fail.
464
465Build issues
466
467- Changed compiler flags, so that gcc is always invoked with -Wall and
468 -Wstrict-prototypes. Users compiling Python with GCC should see
469 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000470 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000471 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000472
Tim Petersa3a3a032000-11-30 05:22:44 +0000473- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000474
475Tools and other miscellany
476
477- The compiler in Tools/compiler was updated to support the new
478 language features introduced in 2.0: extended print statement, list
479 comprehensions, and augmented assignments. The new compiler should
480 also be backwards compatible with Python 1.5.2; the compiler will
481 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000482 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000483
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000484What's new in 2.0 release candidate 1 (since beta 2)?
485=====================================================
486
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000487What is release candidate 1?
488
489We believe that release candidate 1 will fix all known bugs that we
490intend to fix for the 2.0 final release. This release should be a bit
491more stable than the previous betas. We would like to see even more
492widespread testing before the final release, so we are producing this
493release candidate. The final release will be exactly the same unless
494any show-stopping (or brown bag) bugs are found by testers of the
495release candidate.
496
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000497All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000498to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000499
500Core language, builtins, and interpreter
501
502- A bug that caused crashes when __coerce__ was used with augmented
503 assignment, e.g. +=, was fixed.
504
505- Raise ZeroDivisionError when raising zero to a negative number,
506 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
507 power operator and the result of math.pow(0.0, -2.0) will vary by
508 platform. On Linux, it raises a ValueError.
509
510- A bug in Unicode string interpolation was fixed that occasionally
511 caused errors with formats including "%%". For example, the
512 following expression "%% %s" % u"abc" no longer raises a TypeError.
513
514- Compilation of deeply nested expressions raises MemoryError instead
515 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
516
517- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
518 rendering them useless. They are now written in binary mode again.
519
520Standard library
521
522- Keyword arguments are now accepted for most pattern and match object
523 methods in SRE, the standard regular expression engine.
524
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000525- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000526 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000527
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000528- Several bugs in the Unicode handling and error handling in _tkinter
529 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000530
531- Fix memory management errors in Merge() and Tkapp_Call() routines.
532
533- Several changes were made to cStringIO to make it compatible with
534 the file-like object interface and with StringIO. If operations are
535 performed on a closed object, an exception is raised. The truncate
536 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000537 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000538
539- There were many changes made to the linuxaudiodev module and its
540 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000541 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000542
543 Note that this module is named poorly, because it should work
544 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000545 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000546
547 The module now raises exceptions when errors occur instead of
548 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
549 audio) and defines a getptr() method that calls the
550 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
551
552- The library_version attribute, introduced in an earlier beta, was
553 removed because it can not be supported with early versions of the C
554 readline library, which provides no way to determine the version at
555 compile-time.
556
557- The binascii module is now enabled on Win64.
558
Tim Peters46446d62000-10-09 21:19:31 +0000559- tokenize.py no longer suffers "recursion depth" errors when parsing
560 programs with very long string literals.
561
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000562Internals
563
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000564- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000565 which is called when the interpreter starts up to determine where
566 the standard library is installed. These vulnerabilities affect all
567 previous versions of Python and can be exploited by setting very
568 long values for PYTHONHOME or argv[0]. The risk is greatest for a
569 setuid Python script, although use of the wrapper in
570 Misc/setuid-prog.c will eliminate the vulnerability.
571
572- Fixed garbage collection bugs in instance creation that were
573 triggered when errors occurred during initialization. The solution,
574 applied in cPickle and in PyInstance_New(), is to call
575 PyObject_GC_Init() after the initialization of the object's
576 container attributes is complete.
577
578- pyexpat adds definitions of PyModule_AddStringConstant and
579 PyModule_AddObject if the Python version is less than 2.0, which
580 provides compatibility with PyXML on Python 1.5.2.
581
582- If the platform has a bogus definition for LONG_BIT (the number of
583 bits in a long), an error will be reported at compile time.
584
585- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
586 collection crashes and possibly other, unreported crashes.
587
588- Fixed a memory leak in _PyUnicode_Fini().
589
590Build issues
591
592- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000593 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000594 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000595
596- The mmap.PAGESIZE constant is now initialized using sysconf when
597 possible, which eliminates a dependency on -lucb for Reliant UNIX.
598
599- The md5 file should now compile on all platforms.
600
601- The select module now compiles on platforms that do not define
602 POLLRDNORM and related constants.
603
604- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000605 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000606
Jeremy Hylton10921202000-10-09 18:34:12 +0000607- BeOS: A number of changes were made to the build and installation
608 process. ar-fake now operates on a directory of object files.
609 dl_export.h is gone, and its macros now appear on the mwcc command
610 line during build on PPC BeOS.
611
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000612- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000613 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000614
615- Cygwin: Support for shared libraries, Tkinter, and sockets.
616
617- SunOS 4.1.4_JL: Fix test for directory existence in configure.
618
619Tools and other miscellany
620
621- Removed debugging prints from main used with freeze.
622
Tim Peters46446d62000-10-09 21:19:31 +0000623- IDLE auto-indent no longer crashes when it encounters Unicode
624 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000625
626What's new in 2.0 beta 2 (since beta 1)?
627========================================
628
629Core language, builtins, and interpreter
630
Tim Peters482c0212000-09-26 06:33:09 +0000631- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000632 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000633
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000634- Add -h and -V command line options to print the usage message and
635 Python version number and exit immediately.
636
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000637- eval() and exec accept Unicode objects as code parameters.
638
639- getattr() and setattr() now also accept Unicode objects for the
640 attribute name, which are converted to strings using the default
641 encoding before lookup.
642
643- Multiplication on string and Unicode now does proper bounds
644 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
645 string is too long."
646
647- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000648 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000649
Jeremy Hylton1b618592000-09-26 05:32:36 +0000650
651Standard library and extensions
652
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000653- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000654 argument checking; it still takes no arguments.
655
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000656- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000657
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000658- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000659
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000660- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000661
662- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000663 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000664
665- copy: Copy Unicode objects atomically.
666
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000667- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000668
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000669- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000670
Fred Drake67233bc2000-09-26 16:40:27 +0000671- dbm: Add get() and setdefault() methods to dbm object. Add constant
672 `library' to module that names the library used. Added doc strings
673 and method names to error messages. Uses configure to determine
674 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
675 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000676
677- distutils: Update to version 0.9.3.
678
679- dl: Add several dl.RTLD_ constants.
680
681- fpectl: Now supported on FreeBSD.
682
683- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
684 found by the collector will be saved in gc.garbage. This is useful
685 for debugging a program that creates reference cycles.
686
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000687- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000688 of HTTP class. Do not close socket on zero-length response. Do not
689 crash when server sends invalid content-length header.
690
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000691- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000692
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000693- marshal: When reading a short, sign-extend on platforms where shorts
694 are bigger than 16 bits. When reading a long, repair the unportable
695 sign extension that was being done for 64-bit machines. (It assumed
696 that signed right shift sign-extends.)
697
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000698- operator: Add contains(), invert(), __invert__() as aliases for
699 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000700
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000701- os: Add support for popen2() and popen3() on all platforms where
702 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000703
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000704- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000705 clicking on a file in Explorer (or passing the file name to the
706 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000707
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000708- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000709 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000710
711- pickle: Now raises ValueError when an invalid pickle that contains
712 a non-string repr where a string repr was expected. This behavior
713 matches cPickle.
714
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000715- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000716
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000717- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000718
719- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000720 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000721 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000722
723- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000724 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000725
726- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000727 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000728 few cycles during startup since the first call to
729 setdefaultencoding() will initialize the codec registry and the
730 encodings package.
731
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000732- socket: Support for size hint in readlines() method of object returned
733 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000734
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000735- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000736 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000737 is followed by whitespace.
738
Tim Petersa3a3a032000-11-30 05:22:44 +0000739- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000740
741- struct: Check ranges for bytes and shorts.
742
743- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000744 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000745
746- Tkinter: Image objects are now guaranteed to have unique ids. Set
747 event.delta to zero if Tk version doesn't support mousewheel.
748 Removed some debugging prints.
749
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000750- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000751
Fred Drake67233bc2000-09-26 16:40:27 +0000752- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000753 which works around a bug in Norton AntiVirus 2000 that leads directly
754 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000755
756- xml: New version detection code allows PyXML to override standard
757 XML package if PyXML version is greater than 0.6.1.
758
Fred Drake64bb3802000-09-26 16:21:35 +0000759- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
760 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
761 tree only for nodes which are sufficiently interesting to a specific
762 application. Does not provide the HTML-specific extensions. Still
763 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000764
Fred Drake64bb3802000-09-26 16:21:35 +0000765- xml.sax: SAX 2 support for Python, including all the handler
766 interfaces needed to process XML 1.0 compliant XML. Some
767 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000768
Fred Drake64bb3802000-09-26 16:21:35 +0000769- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
770 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000771
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000772
Jeremy Hylton1b618592000-09-26 05:32:36 +0000773C API
774
775- Add three new convenience functions for module initialization --
776 PyModule_AddObject(), PyModule_AddIntConstant(), and
777 PyModule_AddStringConstant().
778
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000779- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000780 removed and add #error to Python.h if NULL isn't defined after
781 #include of stdio.h.
782
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000783- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000784 backwards compatibility (at the source level) with old extensions.
785
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000786- A wrapper API was added for signal() and sigaction(). Instead of
787 either function, always use PyOS_getsig() to get a signal handler
788 and PyOS_setsig() to set one. A new convenience typedef
789 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000790
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000791- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000792 internal data buffer and size of a string object -- or the default
793 encoded version of a Unicode object.
794
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000795- PyString_Size() and PyString_AsString() accept Unicode objects.
796
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000797- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000798 exists). INT_MAX and LONG_MAX will always be defined, even if
799 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000800
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000801- PyFloat_FromString takes a second argument, pend, that was
802 effectively useless. It is now officially useless but preserved for
803 backwards compatibility. If the pend argument is not NULL, *pend is
804 set to NULL.
805
806- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
807 for the attribute name. See note on getattr() above.
808
809- A few bug fixes to argument processing for Unicode.
810 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
811 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
812 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000813 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000814
815- Py_BuildValue accepts B format (for bgen-generated code).
816
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000817
Jeremy Hylton1b618592000-09-26 05:32:36 +0000818Internals
819
820- On Unix, fix code for finding Python installation directory so that
821 it works when argv[0] is a relative path.
822
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000823- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000824 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000825 rather than by generating a copy of the object.
826
Tim Peters482c0212000-09-26 06:33:09 +0000827- Several of the internal Unicode tables are much smaller now, and
828 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000829
Jeremy Hylton97693b02000-09-26 17:42:51 +0000830- In the garbage collector: Fixed bug in collection of tuples. Fixed
831 bug that caused some instances to be removed from the container set
832 while they were still live. Fixed parsing in gc.set_debug() for
833 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000834
835- Fixed refcount problem in instance deallocation that only occurred
836 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
837
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000838- On Windows, getpythonregpath is now protected against null data in
839 registry key.
840
841- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000842 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000843
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000844
Jeremy Hylton1b618592000-09-26 05:32:36 +0000845Build and platform-specific issues
846
847- Better support of GNU Pth via --with-pth configure option.
848
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000849- Python/C API now properly exposed to dynamically-loaded extension
850 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000851
852- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
853 Don't define MS_SYNC to be zero when it is undefined. Added missing
854 prototypes in posixmodule.c.
855
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000856- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000857 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000858
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000859- Fix largefile support on older NetBSD systems and OpenBSD by adding
860 define for TELL64.
861
862
863Tools and other miscellany
864
865- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
866
867- freeze: The modulefinder now works with 2.0 opcodes.
868
Tim Petersa3a3a032000-11-30 05:22:44 +0000869- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000870 Move hackery of sys.argv until after the Tk instance has been
871 created, which allows the application-specific Tkinter
872 initialization to be executed if present; also pass an explicit
873 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000874
Jeremy Hylton1b618592000-09-26 05:32:36 +0000875
876What's new in 2.0 beta 1?
877=========================
878
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000879Source Incompatibilities
880------------------------
881
882None. Note that 1.6 introduced several incompatibilities with 1.5.2,
883such as single-argument append(), connect() and bind(), and changes to
884str(long) and repr(float).
885
886
887Binary Incompatibilities
888------------------------
889
890- Third party extensions built for Python 1.5.x or 1.6 cannot be used
891with Python 2.0; these extensions will have to be rebuilt for Python
8922.0.
893
894- On Windows, attempting to import a third party extension built for
895Python 1.5.x or 1.6 results in an immediate crash; there's not much we
896can do about this. Check your PYTHONPATH environment variable!
897
898- Python bytecode files (*.pyc and *.pyo) are not compatible between
899releases.
900
901
902Overview of Changes Since 1.6
903-----------------------------
904
905There are many new modules (including brand new XML support through
906the xml package, and i18n support through the gettext module); a list
907of all new modules is included below. Lots of bugs have been fixed.
908
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000909The process for making major new changes to the language has changed
910since Python 1.6. Enhancements must now be documented by a Python
911Enhancement Proposal (PEP) before they can be accepted.
912
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000913There are several important syntax enhancements, described in more
914detail below:
915
916 - Augmented assignment, e.g. x += 1
917
918 - List comprehensions, e.g. [x**2 for x in range(10)]
919
920 - Extended import statement, e.g. import Module as Name
921
922 - Extended print statement, e.g. print >> file, "Hello"
923
924Other important changes:
925
926 - Optional collection of cyclical garbage
927
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000928Python Enhancement Proposal (PEP)
929---------------------------------
930
931PEP stands for Python Enhancement Proposal. A PEP is a design
932document providing information to the Python community, or describing
933a new feature for Python. The PEP should provide a concise technical
934specification of the feature and a rationale for the feature.
935
936We intend PEPs to be the primary mechanisms for proposing new
937features, for collecting community input on an issue, and for
938documenting the design decisions that have gone into Python. The PEP
939author is responsible for building consensus within the community and
940documenting dissenting opinions.
941
942The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000943
944Augmented Assignment
945--------------------
946
947This must have been the most-requested feature of the past years!
948Eleven new assignment operators were added:
949
Guido van Rossume905e952000-09-05 12:42:46 +0000950 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000951
952For example,
953
954 A += B
955
956is similar to
957
958 A = A + B
959
960except that A is evaluated only once (relevant when A is something
961like dict[index].attr).
962
963However, if A is a mutable object, A may be modified in place. Thus,
964if A is a number or a string, A += B has the same effect as A = A+B
965(except A is only evaluated once); but if a is a list, A += B has the
966same effect as A.extend(B)!
967
968Classes and built-in object types can override the new operators in
969order to implement the in-place behavior; the not-in-place behavior is
970used automatically as a fallback when an object doesn't implement the
971in-place behavior. For classes, the method name is derived from the
972method name for the corresponding not-in-place operator by inserting
973an 'i' in front of the name, e.g. __iadd__ implements in-place
974__add__.
975
976Augmented assignment was implemented by Thomas Wouters.
977
978
979List Comprehensions
980-------------------
981
982This is a flexible new notation for lists whose elements are computed
983from another list (or lists). The simplest form is:
984
985 [<expression> for <variable> in <sequence>]
986
Guido van Rossum56db0952000-09-06 23:34:25 +0000987For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000988This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000989
990You can also add a condition:
991
992 [<expression> for <variable> in <sequence> if <condition>]
993
994For example, [w for w in words if w == w.lower()] would yield the list
995of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000996than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000997
998You can also have nested for loops and more than one 'if' clause. For
999example, here's a function that flattens a sequence of sequences::
1000
1001 def flatten(seq):
1002 return [x for subseq in seq for x in subseq]
1003
1004 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1005
1006This prints
1007
1008 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1009
1010List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001011Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001012
1013
1014Extended Import Statement
1015-------------------------
1016
1017Many people have asked for a way to import a module under a different
1018name. This can be accomplished like this:
1019
1020 import foo
1021 bar = foo
1022 del foo
1023
1024but this common idiom gets old quickly. A simple extension of the
1025import statement now allows this to be written as follows:
1026
1027 import foo as bar
1028
1029There's also a variant for 'from ... import':
1030
1031 from foo import bar as spam
1032
1033This also works with packages; e.g. you can write this:
1034
1035 import test.regrtest as regrtest
1036
1037Note that 'as' is not a new keyword -- it is recognized only in this
1038context (this is only possible because the syntax for the import
1039statement doesn't involve expressions).
1040
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001041Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001042
1043
1044Extended Print Statement
1045------------------------
1046
1047Easily the most controversial new feature, this extension to the print
1048statement adds an option to make the output go to a different file
1049than the default sys.stdout.
1050
1051For example, to write an error message to sys.stderr, you can now
1052write:
1053
1054 print >> sys.stderr, "Error: bad dog!"
1055
1056As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001057evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001058
1059 print >> None, "Hello world"
1060
1061is equivalent to
1062
1063 print "Hello world"
1064
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001065Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001066
1067
1068Optional Collection of Cyclical Garbage
1069---------------------------------------
1070
1071Python is now equipped with a garbage collector that can hunt down
1072cyclical references between Python objects. It's no replacement for
1073reference counting; in fact, it depends on the reference counts being
1074correct, and decides that a set of objects belong to a cycle if all
1075their reference counts can be accounted for from their references to
1076each other. This devious scheme was first proposed by Eric Tiedemann,
1077and brought to implementation by Neil Schemenauer.
1078
1079There's a module "gc" that lets you control some parameters of the
1080garbage collection. There's also an option to the configure script
1081that lets you enable or disable the garbage collection. In 2.0b1,
1082it's on by default, so that we (hopefully) can collect decent user
1083experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001084performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001085off by default in the final 2.0 release.
1086
1087
1088Smaller Changes
1089---------------
1090
1091A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1092map(None, seq1, seq2, ...) when the sequences have the same length;
1093i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1094the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001095zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001096
1097sys.version_info is a tuple (major, minor, micro, level, serial).
1098
1099Dictionaries have an odd new method, setdefault(key, default).
1100dict.setdefault(key, default) returns dict[key] if it exists; if not,
1101it sets dict[key] to default and returns that value. Thus:
1102
1103 dict.setdefault(key, []).append(item)
1104
1105does the same work as this common idiom:
1106
1107 if not dict.has_key(key):
1108 dict[key] = []
1109 dict[key].append(item)
1110
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001111There are two new variants of SyntaxError that are raised for
1112indentation-related errors: IndentationError and TabError.
1113
1114Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1115escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001116
1117The limits on the size of expressions and file in Python source code
1118have been raised from 2**16 to 2**32. Previous versions of Python
1119were limited because the maximum argument size the Python VM accepted
1120was 2**16. This limited the size of object constructor expressions,
1121e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1122limit was raised thanks to a patch by Charles Waldman that effectively
1123fixes the problem. It is now much more likely that you will be
1124limited by available memory than by an arbitrary limit in Python.
1125
1126The interpreter's maximum recursion depth can be modified by Python
1127programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1128limit is the maximum number of recursive calls that can be made by
1129Python code. The limit exists to prevent infinite recursion from
1130overflowing the C stack and causing a core dump. The default value is
11311000. The maximum safe value for a particular platform can be found
1132by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001133
1134New Modules and Packages
1135------------------------
1136
1137atexit - for registering functions to be called when Python exits.
1138
1139imputil - Greg Stein's alternative API for writing custom import
1140hooks.
1141
1142pyexpat - an interface to the Expat XML parser, contributed by Paul
1143Prescod.
1144
1145xml - a new package with XML support code organized (so far) in three
1146subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1147would fill a volume. There's a special feature whereby a
1148user-installed package named _xmlplus overrides the standard
1149xmlpackage; this is intended to give the XML SIG a hook to distribute
1150backwards-compatible updates to the standard xml package.
1151
1152webbrowser - a platform-independent API to launch a web browser.
1153
1154
Guido van Rossume905e952000-09-05 12:42:46 +00001155Changed Modules
1156---------------
1157
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001158array -- new methods for array objects: count, extend, index, pop, and
1159remove
1160
1161binascii -- new functions b2a_hex and a2b_hex that convert between
1162binary data and its hex representation
1163
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001164calendar -- Many new functions that support features including control
1165over which day of the week is the first day, returning strings instead
1166of printing them. Also new symbolic constants for days of week,
1167e.g. MONDAY, ..., SUNDAY.
1168
1169cgi -- FieldStorage objects have a getvalue method that works like a
1170dictionary's get method and returns the value attribute of the object.
1171
1172ConfigParser -- The parser object has new methods has_option,
1173remove_section, remove_option, set, and write. They allow the module
1174to be used for writing config files as well as reading them.
1175
1176ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001177optionally support the RFC 959 REST command.
1178
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001179gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001180
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001181httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1182the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001183
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001184locale -- implement getdefaultlocale for Win32 and Macintosh
1185
1186marshal -- no longer dumps core when marshaling deeply nested or
1187recursive data structures
1188
1189os -- new functions isatty, seteuid, setegid, setreuid, setregid
1190
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001191os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1192support under Unix.
1193
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001194os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001195
1196os.path -- fix semantics of os.path.commonprefix
1197
1198smtplib -- support for sending very long messages
1199
1200socket -- new function getfqdn()
1201
1202readline -- new functions to read, write and truncate history files.
1203The readline section of the library reference manual contains an
1204example.
1205
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001206select -- add interface to poll system call
1207
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001208shutil -- new copyfileobj function
1209
1210SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1211HTTP server.
1212
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001213Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001214
1215urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001216e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001217
1218whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001219
1220
1221Obsolete Modules
1222----------------
1223
1224None. However note that 1.6 made a whole slew of modules obsolete:
1225stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1226poly, zmod, strop, util, whatsound.
1227
1228
1229Changed, New, Obsolete Tools
1230----------------------------
1231
Tim Peters8b092332000-09-05 20:15:25 +00001232None.
Guido van Rossume905e952000-09-05 12:42:46 +00001233
1234
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001235C-level Changes
1236---------------
1237
1238Several cleanup jobs were carried out throughout the source code.
1239
1240All C code was converted to ANSI C; we got rid of all uses of the
1241Py_PROTO() macro, which makes the header files a lot more readable.
1242
1243Most of the portability hacks were moved to a new header file,
1244pyport.h; several other new header files were added and some old
1245header files were removed, in an attempt to create a more rational set
1246of header files. (Few of these ever need to be included explicitly;
1247they are all included by Python.h.)
1248
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001249Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001250and Win64, especially for the new Intel Itanium processor. Mick also
1251added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001252
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001253The C APIs to return an object's size have been update to consistently
1254use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1255previous versions, the abstract interfaces used PyXXX_Length and the
1256concrete interfaces used PyXXX_Size. The old names,
1257e.g. PyObject_Length, are still available for backwards compatibility
1258at the API level, but are deprecated.
1259
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001260The PyOS_CheckStack function has been implemented on Windows by
1261Fredrik Lundh. It prevents Python from failing with a stack overflow
1262on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001263
1264The GC changes resulted in creation of two new slots on object,
1265tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001266the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001267
1268The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001269C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001270
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001271PyErr_Format has been updated to automatically calculate the size of
1272the buffer needed to hold the formatted result string. This change
1273prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001274
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001275New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001276
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001277PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1278that are the same as their non-Ex counterparts except they take an
1279extra flag argument that tells them to close the file when done.
1280
1281XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001282
Tim Peters8b092332000-09-05 20:15:25 +00001283
1284Windows Changes
1285---------------
1286
1287New popen2/popen3/peopen4 in os module (see Changed Modules above).
1288
1289os.popen is much more usable on Windows 95 and 98. See Microsoft
1290Knowledge Base article Q150956. The Win9x workaround described there
1291is implemented by the new w9xpopen.exe helper in the root of your
1292Python installation. Note that Python uses this internally; it is not
1293a standalone program.
1294
1295Administrator privileges are no longer required to install Python
1296on Windows NT or Windows 2000. If you have administrator privileges,
1297Python's registry info will be written under HKEY_LOCAL_MACHINE.
1298Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001299under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001300uses of Python, but will prevent some advanced uses from working
1301(for example, running a Python script as an NT service, or possibly
1302from CGI).
1303
1304[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1305installer; instead, it installs the needed Tcl/Tk files directly in the
1306Python directory. If you already have a Tcl/Tk installation, this
1307wastes some disk space (about 4 Megs) but avoids problems with
1308conflicting Tcl/Tk installations, and makes it much easier for Python
1309to ensure that Tcl/Tk can find all its files.
1310
1311[This was new in 1.6] The Windows installer now installs by default in
1312\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1313
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001314
1315Updates to the changes between 1.5.2 and 1.6
1316--------------------------------------------
1317
1318The 1.6 NEWS file can't be changed after the release is done, so here
1319is some late-breaking news:
1320
1321New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1322and changes to getlocale() and setlocale().
1323
1324The new module is now enabled per default.
1325
1326It is not true that the encodings codecs cannot be used for normal
1327strings: the string.encode() (which is also present on 8-bit strings
1328!) allows using them for 8-bit strings too, e.g. to convert files from
1329cp1252 (Windows) to latin-1 or vice-versa.
1330
1331Japanese codecs are available from Tamito KAJIYAMA:
1332http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1333
1334
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001335======================================================================