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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
Tim Peters14495852001-02-18 08:28:33 +0000186- The outcome of comparing non-numeric objects of differerent types is
187 not defined by the language, other than that it's arbitrary but
188 consistent (see the Reference Manual). An implementation detail changed
189 in 2.1a1 such that None now compares less than any other object. Code
190 relying on this new behavior (like code that relied on the previous
191 behavior) does so at its own risk.
192
Barry Warsaw573b5412001-01-15 20:43:18 +0000193- Functions and methods now support getting and setting arbitrarily
194 named attributes (PEP 232). Functions have a new __dict__
195 (a.k.a. func_dict) which hold the function attributes. Methods get
196 and set attributes on their underlying im_func. It is a TypeError
197 to set an attribute on a bound method.
198
Guido van Rossum051e3352001-01-15 19:11:10 +0000199- The xrange() object implementation has been improved so that
200 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
201 limitation that in this case len(xrange(sys.maxint)) can't be
202 calculated, but the common idiom "for i in xrange(sys.maxint)" will
203 work fine as long as the index i doesn't actually reach 2**31.
204 (Python uses regular ints for sequence and string indices; fixing
205 that is much more work.)
206
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000207- Two changes to from...import:
208
Guido van Rossumba381232001-02-03 15:06:40 +0000209 1) "from M import X" now works even if (after loading module M)
210 sys.modules['M'] is not a real module; it's basically a getattr()
211 operation with AttributeError exceptions changed into ImportError.
Guido van Rossum1cc8f832001-01-12 16:25:08 +0000212
213 2) "from M import *" now looks for M.__all__ to decide which names to
214 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
215 filters out names starting with '_' as before. Whether or not
216 __all__ exists, there's no restriction on the type of M.
217
Guido van Rossumf61f1662001-01-10 20:13:55 +0000218- File objects have a new method, xreadlines(). This is the fastest
219 way to iterate over all lines in a file:
220
221 for line in file.xreadlines():
222 ...do something to line...
223
224 See the xreadlines module (mentioned below) for how to do this for
225 other file-like objects.
226
227- Even if you don't use file.xreadlines(), you may expect a speedup on
228 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +0000229 quite a bit in platform-specific ways: on systems (like Linux) that
230 support flockfile(), getc_unlocked(), and funlockfile(), those are
231 used by default. On systems (like Windows) without getc_unlocked(),
232 a complicated (but still thread-safe) method using fgets() is used by
233 default.
234
Tim Petersd52269b2001-01-25 06:23:18 +0000235 You can force use of the fgets() method by #define'ing
236 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +0000237 getc_unlocked()).
238
Tim Petersd52269b2001-01-25 06:23:18 +0000239 You can force fgets() not to be used by #define'ing
240 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +0000241 test_bufio.py fails -- and let us know if it does!).
242
243- In addition, the fileinput module, while still slower than the other
244 methods on most platforms, has been sped up too, by using
245 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000246
247- Support for run-time warnings has been added, including a new
248 command line option (-W) to specify the disposition of warnings.
249 See the description of the warnings module below.
250
251- Extensive changes have been made to the coercion code. This mostly
252 affects extension modules (which can now implement mixed-type
253 numerical operators without having to use coercion), but
254 occasionally, in boundary cases the coercion semantics have changed
255 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000256 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000257 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000258 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000259
Guido van Rossumf98eda02001-01-17 15:54:45 +0000260- In connection with the coercion changes, a new built-in singleton
261 object, NotImplemented is defined. This can be returned for
262 operations that wish to indicate they are not implemented for a
263 particular combination of arguments. From C, this is
264 Py_NotImplemented.
265
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000266- The interpreter accepts now bytecode files on the command line even
267 if they do not have a .pyc or .pyo extension. On Linux, after executing
268
Martin v. Löwise214baa2001-02-04 22:37:56 +0000269import imp,sys,string
270magic = string.join(["\\x%.2x" % ord(c) for c in imp.get_magic()],"")
271reg = ':pyc:M::%s::%s:' % (magic, sys.executable)
272open("/proc/sys/fs/binfmt_misc/register","wb").write(reg)
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000273
274 any byte code file can be used as an executable (i.e. as an argument
275 to execve(2)).
276
Tim Peters9940b802000-12-01 07:59:35 +0000277- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000278 character. In 1.6 and earlier, they never produced a sign,
279 and raised an error if the value of the long was too large
280 to fit in a Python int. In 2.0, they produced a sign if and
281 only if too large to fit in an int. This was inconsistent
282 across platforms (because the size of an int varies across
283 platforms), and inconsistent with hex() and oct(). Example:
284
285 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000286 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000287 'ffffffbe' # in 2.0 and before, on 32-bit machines
288 >>> hex(-0x42L)
289 '-0x42L' # in all versions of Python
290
Tim Peters9940b802000-12-01 07:59:35 +0000291 The behavior of %d formats for negative Python longs remains
292 the same as in 2.0 (although in 1.6 and before, they raised
293 an error if the long didn't fit in a Python int).
294
295 %u formats don't make sense for Python longs, but are allowed
296 and treated the same as %d in 2.1. In 2.0, a negative long
297 formatted via %u produced a sign if and only if too large to
298 fit in an int. In 1.6 and earlier, a negative long formatted
299 via %u raised an error if it was too big to fit in an int.
300
Guido van Rossum3661d392000-12-12 22:10:31 +0000301- Dictionary objects have an odd new method, popitem(). This removes
302 an arbitrary item from the dictionary and returns it (in the form of
303 a (key, value) pair). This can be useful for algorithms that use a
304 dictionary as a bag of "to do" items and repeatedly need to pick one
305 item. Such algorithms normally end up running in quadratic time;
306 using popitem() they can usually be made to run in linear time.
307
Tim Peters36cdad12000-12-29 02:06:45 +0000308Standard library
309
Thomas Woutersfe385252001-01-19 23:16:56 +0000310- In the time module, the time argument to the functions strftime,
311 localtime, gmtime, asctime and ctime is now optional, defaulting to
312 the current time (in the local timezone).
313
Guido van Rossumda91f222001-01-15 16:36:08 +0000314- The ftplib module now defaults to passive mode, which is deemed a
315 more useful default given that clients are often inside firewalls
316 these days. Note that this could break if ftplib is used to connect
317 to a *server* that is inside a firewall, from outside; this is
318 expected to be a very rare situation. To fix that, you can call
319 ftp.set_pasv(0).
320
Martin v. Löwis10a27872001-01-13 09:54:41 +0000321- The module site now treats .pth files not only for path configuration,
322 but also supports extensions to the initialization code: Lines starting
323 with import are executed.
324
Guido van Rossumf61f1662001-01-10 20:13:55 +0000325- There's a new module, warnings, which implements a mechanism for
326 issuing and filtering warnings. There are some new built-in
327 exceptions that serve as warning categories, and a new command line
328 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
329 turns warnings into errors). warnings.warn(message[, category])
330 issues a warning message; this can also be called from C as
331 PyErr_Warn(category, message).
332
333- A new module xreadlines was added. This exports a single factory
334 function, xreadlines(). The intention is that this code is the
335 absolutely fastest way to iterate over all lines in an open
336 file(-like) object:
337
338 import xreadlines
339 for line in xreadlines.xreadlines(file):
340 ...do something to line...
341
342 This is equivalent to the previous the speed record holder using
343 file.readlines(sizehint). Note that if file is a real file object
344 (as opposed to a file-like object), this is equivalent:
345
346 for line in file.xreadlines():
347 ...do something to line...
348
Tim Peters36cdad12000-12-29 02:06:45 +0000349- The bisect module has new functions bisect_left, insort_left,
350 bisect_right and insort_right. The old names bisect and insort
351 are now aliases for bisect_right and insort_right. XXX_right
352 and XXX_left methods differ in what happens when the new element
353 compares equal to one or more elements already in the list: the
354 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000355 right. Code that doesn't care where equal elements end up should
356 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000357
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000358- The new curses.panel module wraps the panel library that forms part
359 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
360
Guido van Rossumf61f1662001-01-10 20:13:55 +0000361- The SocketServer module now sets the allow_reuse_address flag by
362 default in the TCPServer class.
363
364- A new function, sys._getframe(), returns the stack frame pointer of
365 the caller. This is intended only as a building block for
366 higher-level mechanisms such as string interpolation.
367
368Build issues
369
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000370- For Unix (and Unix-compatible) builds, configuration and building of
371 extension modules is now greatly automated. Rather than having to
372 edit the Modules/Setup file to indicate which modules should be
373 built and where their include files and libraries are, a
374 distutils-based setup.py script now takes care of building most
375 extension modules. All extension modules built this way are built
376 as shared libraries. Only a few modules that must be linked
377 statically are still listed in the Setup file; you won't need to
378 edit their configuration.
379
380- Python should now build out of the box on Cygwin. If it doesn't,
381 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000382
383- Python now always uses its own (renamed) implementation of getopt()
384 -- there's too much variation among C library getopt()
385 implementations.
386
387- C++ compilers are better supported; the CXX macro is always set to a
388 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000389
Tim Petersd92dfe02000-12-12 01:18:41 +0000390Windows changes
391
392- select module: By default under Windows, a select() call
393 can specify no more than 64 sockets. Python now boosts
394 this Microsoft default to 512. If you need even more than
395 that, see the MS docs (you'll need to #define FD_SETSIZE
396 and recompile Python from source).
397
Guido van Rossumf61f1662001-01-10 20:13:55 +0000398- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
399 subdirectory is no more!
400
Tim Petersa3a3a032000-11-30 05:22:44 +0000401
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000402What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000403=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000404
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000405Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000406changes are in the file HISTORY. If you are making the jump directly
407from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
408HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000409
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000410Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
411the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
412http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000413
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000414--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000415
416======================================================================
417
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000418What's new in 2.0 (since release candidate 1)?
419==============================================
420
421Standard library
422
423- The copy_reg module was modified to clarify its intended use: to
424 register pickle support for extension types, not for classes.
425 pickle() will raise a TypeError if it is passed a class.
426
427- Fixed a bug in gettext's "normalize and expand" code that prevented
428 it from finding an existing .mo file.
429
430- Restored support for HTTP/0.9 servers in httplib.
431
Tim Peters989b7b92000-10-16 20:24:53 +0000432- The math module was changed to stop raising OverflowError in case of
433 underflow, and return 0 instead in underflow cases. Whether Python
434 used to raise OverflowError in case of underflow was platform-
435 dependent (it did when the platform math library set errno to ERANGE
436 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000437
438- Fixed a bug in StringIO that occurred when the file position was not
439 at the end of the file and write() was called with enough data to
440 extend past the end of the file.
441
442- Fixed a bug that caused Tkinter error messages to get lost on
443 Windows. The bug was fixed by replacing direct use of
444 interp->result with Tcl_GetStringResult(interp).
445
446- Fixed bug in urllib2 that caused it to fail when it received an HTTP
447 redirect response.
448
449- Several changes were made to distutils: Some debugging code was
450 removed from util. Fixed the installer used when an external zip
451 program (like WinZip) is not found; the source code for this
452 installer is in Misc/distutils. check_lib() was modified to behave
453 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
454 test for whether installed modules are on sys.path was changed to
455 use both normcase() and normpath().
456
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000457- Several minor bugs were fixed in the xml package (the minidom,
458 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000459
460- The regression test driver (regrtest.py) behavior when invoked with
461 -l changed: It now reports a count of objects that are recognized as
462 garbage but not freed by the garbage collector.
463
Tim Peters989b7b92000-10-16 20:24:53 +0000464- The regression test for the math module was changed to test
465 exceptional behavior when the test is run in verbose mode. Python
466 cannot yet guarantee consistent exception behavior across platforms,
467 so the exception part of test_math is run only in verbose mode, and
468 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000469
470Internals
471
472- PyOS_CheckStack() has been disabled on Win64, where it caused
473 test_sre to fail.
474
475Build issues
476
477- Changed compiler flags, so that gcc is always invoked with -Wall and
478 -Wstrict-prototypes. Users compiling Python with GCC should see
479 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000480 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000481 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000482
Tim Petersa3a3a032000-11-30 05:22:44 +0000483- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000484
485Tools and other miscellany
486
487- The compiler in Tools/compiler was updated to support the new
488 language features introduced in 2.0: extended print statement, list
489 comprehensions, and augmented assignments. The new compiler should
490 also be backwards compatible with Python 1.5.2; the compiler will
491 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000492 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000493
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000494What's new in 2.0 release candidate 1 (since beta 2)?
495=====================================================
496
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000497What is release candidate 1?
498
499We believe that release candidate 1 will fix all known bugs that we
500intend to fix for the 2.0 final release. This release should be a bit
501more stable than the previous betas. We would like to see even more
502widespread testing before the final release, so we are producing this
503release candidate. The final release will be exactly the same unless
504any show-stopping (or brown bag) bugs are found by testers of the
505release candidate.
506
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000507All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000508to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000509
510Core language, builtins, and interpreter
511
512- A bug that caused crashes when __coerce__ was used with augmented
513 assignment, e.g. +=, was fixed.
514
515- Raise ZeroDivisionError when raising zero to a negative number,
516 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
517 power operator and the result of math.pow(0.0, -2.0) will vary by
518 platform. On Linux, it raises a ValueError.
519
520- A bug in Unicode string interpolation was fixed that occasionally
521 caused errors with formats including "%%". For example, the
522 following expression "%% %s" % u"abc" no longer raises a TypeError.
523
524- Compilation of deeply nested expressions raises MemoryError instead
525 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
526
527- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
528 rendering them useless. They are now written in binary mode again.
529
530Standard library
531
532- Keyword arguments are now accepted for most pattern and match object
533 methods in SRE, the standard regular expression engine.
534
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000535- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000536 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000537
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000538- Several bugs in the Unicode handling and error handling in _tkinter
539 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000540
541- Fix memory management errors in Merge() and Tkapp_Call() routines.
542
543- Several changes were made to cStringIO to make it compatible with
544 the file-like object interface and with StringIO. If operations are
545 performed on a closed object, an exception is raised. The truncate
546 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000547 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000548
549- There were many changes made to the linuxaudiodev module and its
550 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000551 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000552
553 Note that this module is named poorly, because it should work
554 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000555 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000556
557 The module now raises exceptions when errors occur instead of
558 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
559 audio) and defines a getptr() method that calls the
560 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
561
562- The library_version attribute, introduced in an earlier beta, was
563 removed because it can not be supported with early versions of the C
564 readline library, which provides no way to determine the version at
565 compile-time.
566
567- The binascii module is now enabled on Win64.
568
Tim Peters46446d62000-10-09 21:19:31 +0000569- tokenize.py no longer suffers "recursion depth" errors when parsing
570 programs with very long string literals.
571
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000572Internals
573
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000574- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000575 which is called when the interpreter starts up to determine where
576 the standard library is installed. These vulnerabilities affect all
577 previous versions of Python and can be exploited by setting very
578 long values for PYTHONHOME or argv[0]. The risk is greatest for a
579 setuid Python script, although use of the wrapper in
580 Misc/setuid-prog.c will eliminate the vulnerability.
581
582- Fixed garbage collection bugs in instance creation that were
583 triggered when errors occurred during initialization. The solution,
584 applied in cPickle and in PyInstance_New(), is to call
585 PyObject_GC_Init() after the initialization of the object's
586 container attributes is complete.
587
588- pyexpat adds definitions of PyModule_AddStringConstant and
589 PyModule_AddObject if the Python version is less than 2.0, which
590 provides compatibility with PyXML on Python 1.5.2.
591
592- If the platform has a bogus definition for LONG_BIT (the number of
593 bits in a long), an error will be reported at compile time.
594
595- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
596 collection crashes and possibly other, unreported crashes.
597
598- Fixed a memory leak in _PyUnicode_Fini().
599
600Build issues
601
602- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000603 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000604 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000605
606- The mmap.PAGESIZE constant is now initialized using sysconf when
607 possible, which eliminates a dependency on -lucb for Reliant UNIX.
608
609- The md5 file should now compile on all platforms.
610
611- The select module now compiles on platforms that do not define
612 POLLRDNORM and related constants.
613
614- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000615 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000616
Jeremy Hylton10921202000-10-09 18:34:12 +0000617- BeOS: A number of changes were made to the build and installation
618 process. ar-fake now operates on a directory of object files.
619 dl_export.h is gone, and its macros now appear on the mwcc command
620 line during build on PPC BeOS.
621
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000622- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000623 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000624
625- Cygwin: Support for shared libraries, Tkinter, and sockets.
626
627- SunOS 4.1.4_JL: Fix test for directory existence in configure.
628
629Tools and other miscellany
630
631- Removed debugging prints from main used with freeze.
632
Tim Peters46446d62000-10-09 21:19:31 +0000633- IDLE auto-indent no longer crashes when it encounters Unicode
634 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000635
636What's new in 2.0 beta 2 (since beta 1)?
637========================================
638
639Core language, builtins, and interpreter
640
Tim Peters482c0212000-09-26 06:33:09 +0000641- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000642 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000643
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000644- Add -h and -V command line options to print the usage message and
645 Python version number and exit immediately.
646
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000647- eval() and exec accept Unicode objects as code parameters.
648
649- getattr() and setattr() now also accept Unicode objects for the
650 attribute name, which are converted to strings using the default
651 encoding before lookup.
652
653- Multiplication on string and Unicode now does proper bounds
654 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
655 string is too long."
656
657- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000658 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000659
Jeremy Hylton1b618592000-09-26 05:32:36 +0000660
661Standard library and extensions
662
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000663- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000664 argument checking; it still takes no arguments.
665
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000666- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000667
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000668- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000669
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000670- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000671
672- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000673 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000674
675- copy: Copy Unicode objects atomically.
676
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000677- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000678
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000679- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000680
Fred Drake67233bc2000-09-26 16:40:27 +0000681- dbm: Add get() and setdefault() methods to dbm object. Add constant
682 `library' to module that names the library used. Added doc strings
683 and method names to error messages. Uses configure to determine
684 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
685 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000686
687- distutils: Update to version 0.9.3.
688
689- dl: Add several dl.RTLD_ constants.
690
691- fpectl: Now supported on FreeBSD.
692
693- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
694 found by the collector will be saved in gc.garbage. This is useful
695 for debugging a program that creates reference cycles.
696
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000697- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000698 of HTTP class. Do not close socket on zero-length response. Do not
699 crash when server sends invalid content-length header.
700
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000701- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000702
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000703- marshal: When reading a short, sign-extend on platforms where shorts
704 are bigger than 16 bits. When reading a long, repair the unportable
705 sign extension that was being done for 64-bit machines. (It assumed
706 that signed right shift sign-extends.)
707
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000708- operator: Add contains(), invert(), __invert__() as aliases for
709 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000710
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000711- os: Add support for popen2() and popen3() on all platforms where
712 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000713
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000714- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000715 clicking on a file in Explorer (or passing the file name to the
716 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000717
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000718- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000719 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000720
721- pickle: Now raises ValueError when an invalid pickle that contains
722 a non-string repr where a string repr was expected. This behavior
723 matches cPickle.
724
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000725- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000726
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000727- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000728
729- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000730 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000731 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000732
733- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000734 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000735
736- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000737 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000738 few cycles during startup since the first call to
739 setdefaultencoding() will initialize the codec registry and the
740 encodings package.
741
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000742- socket: Support for size hint in readlines() method of object returned
743 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000744
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000745- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000746 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000747 is followed by whitespace.
748
Tim Petersa3a3a032000-11-30 05:22:44 +0000749- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000750
751- struct: Check ranges for bytes and shorts.
752
753- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000754 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000755
756- Tkinter: Image objects are now guaranteed to have unique ids. Set
757 event.delta to zero if Tk version doesn't support mousewheel.
758 Removed some debugging prints.
759
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000760- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000761
Fred Drake67233bc2000-09-26 16:40:27 +0000762- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000763 which works around a bug in Norton AntiVirus 2000 that leads directly
764 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000765
766- xml: New version detection code allows PyXML to override standard
767 XML package if PyXML version is greater than 0.6.1.
768
Fred Drake64bb3802000-09-26 16:21:35 +0000769- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
770 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
771 tree only for nodes which are sufficiently interesting to a specific
772 application. Does not provide the HTML-specific extensions. Still
773 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000774
Fred Drake64bb3802000-09-26 16:21:35 +0000775- xml.sax: SAX 2 support for Python, including all the handler
776 interfaces needed to process XML 1.0 compliant XML. Some
777 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000778
Fred Drake64bb3802000-09-26 16:21:35 +0000779- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
780 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000781
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000782
Jeremy Hylton1b618592000-09-26 05:32:36 +0000783C API
784
785- Add three new convenience functions for module initialization --
786 PyModule_AddObject(), PyModule_AddIntConstant(), and
787 PyModule_AddStringConstant().
788
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000789- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000790 removed and add #error to Python.h if NULL isn't defined after
791 #include of stdio.h.
792
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000793- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000794 backwards compatibility (at the source level) with old extensions.
795
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000796- A wrapper API was added for signal() and sigaction(). Instead of
797 either function, always use PyOS_getsig() to get a signal handler
798 and PyOS_setsig() to set one. A new convenience typedef
799 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000800
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000801- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000802 internal data buffer and size of a string object -- or the default
803 encoded version of a Unicode object.
804
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000805- PyString_Size() and PyString_AsString() accept Unicode objects.
806
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000807- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000808 exists). INT_MAX and LONG_MAX will always be defined, even if
809 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000810
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000811- PyFloat_FromString takes a second argument, pend, that was
812 effectively useless. It is now officially useless but preserved for
813 backwards compatibility. If the pend argument is not NULL, *pend is
814 set to NULL.
815
816- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
817 for the attribute name. See note on getattr() above.
818
819- A few bug fixes to argument processing for Unicode.
820 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
821 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
822 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000823 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000824
825- Py_BuildValue accepts B format (for bgen-generated code).
826
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000827
Jeremy Hylton1b618592000-09-26 05:32:36 +0000828Internals
829
830- On Unix, fix code for finding Python installation directory so that
831 it works when argv[0] is a relative path.
832
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000833- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000834 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000835 rather than by generating a copy of the object.
836
Tim Peters482c0212000-09-26 06:33:09 +0000837- Several of the internal Unicode tables are much smaller now, and
838 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000839
Jeremy Hylton97693b02000-09-26 17:42:51 +0000840- In the garbage collector: Fixed bug in collection of tuples. Fixed
841 bug that caused some instances to be removed from the container set
842 while they were still live. Fixed parsing in gc.set_debug() for
843 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000844
845- Fixed refcount problem in instance deallocation that only occurred
846 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
847
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000848- On Windows, getpythonregpath is now protected against null data in
849 registry key.
850
851- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000852 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000853
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000854
Jeremy Hylton1b618592000-09-26 05:32:36 +0000855Build and platform-specific issues
856
857- Better support of GNU Pth via --with-pth configure option.
858
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000859- Python/C API now properly exposed to dynamically-loaded extension
860 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000861
862- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
863 Don't define MS_SYNC to be zero when it is undefined. Added missing
864 prototypes in posixmodule.c.
865
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000866- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000867 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000868
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000869- Fix largefile support on older NetBSD systems and OpenBSD by adding
870 define for TELL64.
871
872
873Tools and other miscellany
874
875- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
876
877- freeze: The modulefinder now works with 2.0 opcodes.
878
Tim Petersa3a3a032000-11-30 05:22:44 +0000879- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000880 Move hackery of sys.argv until after the Tk instance has been
881 created, which allows the application-specific Tkinter
882 initialization to be executed if present; also pass an explicit
883 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000884
Jeremy Hylton1b618592000-09-26 05:32:36 +0000885
886What's new in 2.0 beta 1?
887=========================
888
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000889Source Incompatibilities
890------------------------
891
892None. Note that 1.6 introduced several incompatibilities with 1.5.2,
893such as single-argument append(), connect() and bind(), and changes to
894str(long) and repr(float).
895
896
897Binary Incompatibilities
898------------------------
899
900- Third party extensions built for Python 1.5.x or 1.6 cannot be used
901with Python 2.0; these extensions will have to be rebuilt for Python
9022.0.
903
904- On Windows, attempting to import a third party extension built for
905Python 1.5.x or 1.6 results in an immediate crash; there's not much we
906can do about this. Check your PYTHONPATH environment variable!
907
908- Python bytecode files (*.pyc and *.pyo) are not compatible between
909releases.
910
911
912Overview of Changes Since 1.6
913-----------------------------
914
915There are many new modules (including brand new XML support through
916the xml package, and i18n support through the gettext module); a list
917of all new modules is included below. Lots of bugs have been fixed.
918
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000919The process for making major new changes to the language has changed
920since Python 1.6. Enhancements must now be documented by a Python
921Enhancement Proposal (PEP) before they can be accepted.
922
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000923There are several important syntax enhancements, described in more
924detail below:
925
926 - Augmented assignment, e.g. x += 1
927
928 - List comprehensions, e.g. [x**2 for x in range(10)]
929
930 - Extended import statement, e.g. import Module as Name
931
932 - Extended print statement, e.g. print >> file, "Hello"
933
934Other important changes:
935
936 - Optional collection of cyclical garbage
937
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000938Python Enhancement Proposal (PEP)
939---------------------------------
940
941PEP stands for Python Enhancement Proposal. A PEP is a design
942document providing information to the Python community, or describing
943a new feature for Python. The PEP should provide a concise technical
944specification of the feature and a rationale for the feature.
945
946We intend PEPs to be the primary mechanisms for proposing new
947features, for collecting community input on an issue, and for
948documenting the design decisions that have gone into Python. The PEP
949author is responsible for building consensus within the community and
950documenting dissenting opinions.
951
952The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000953
954Augmented Assignment
955--------------------
956
957This must have been the most-requested feature of the past years!
958Eleven new assignment operators were added:
959
Guido van Rossume905e952000-09-05 12:42:46 +0000960 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000961
962For example,
963
964 A += B
965
966is similar to
967
968 A = A + B
969
970except that A is evaluated only once (relevant when A is something
971like dict[index].attr).
972
973However, if A is a mutable object, A may be modified in place. Thus,
974if A is a number or a string, A += B has the same effect as A = A+B
975(except A is only evaluated once); but if a is a list, A += B has the
976same effect as A.extend(B)!
977
978Classes and built-in object types can override the new operators in
979order to implement the in-place behavior; the not-in-place behavior is
980used automatically as a fallback when an object doesn't implement the
981in-place behavior. For classes, the method name is derived from the
982method name for the corresponding not-in-place operator by inserting
983an 'i' in front of the name, e.g. __iadd__ implements in-place
984__add__.
985
986Augmented assignment was implemented by Thomas Wouters.
987
988
989List Comprehensions
990-------------------
991
992This is a flexible new notation for lists whose elements are computed
993from another list (or lists). The simplest form is:
994
995 [<expression> for <variable> in <sequence>]
996
Guido van Rossum56db0952000-09-06 23:34:25 +0000997For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000998This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000999
1000You can also add a condition:
1001
1002 [<expression> for <variable> in <sequence> if <condition>]
1003
1004For example, [w for w in words if w == w.lower()] would yield the list
1005of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001006than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001007
1008You can also have nested for loops and more than one 'if' clause. For
1009example, here's a function that flattens a sequence of sequences::
1010
1011 def flatten(seq):
1012 return [x for subseq in seq for x in subseq]
1013
1014 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
1015
1016This prints
1017
1018 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1019
1020List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001021Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001022
1023
1024Extended Import Statement
1025-------------------------
1026
1027Many people have asked for a way to import a module under a different
1028name. This can be accomplished like this:
1029
1030 import foo
1031 bar = foo
1032 del foo
1033
1034but this common idiom gets old quickly. A simple extension of the
1035import statement now allows this to be written as follows:
1036
1037 import foo as bar
1038
1039There's also a variant for 'from ... import':
1040
1041 from foo import bar as spam
1042
1043This also works with packages; e.g. you can write this:
1044
1045 import test.regrtest as regrtest
1046
1047Note that 'as' is not a new keyword -- it is recognized only in this
1048context (this is only possible because the syntax for the import
1049statement doesn't involve expressions).
1050
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001051Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001052
1053
1054Extended Print Statement
1055------------------------
1056
1057Easily the most controversial new feature, this extension to the print
1058statement adds an option to make the output go to a different file
1059than the default sys.stdout.
1060
1061For example, to write an error message to sys.stderr, you can now
1062write:
1063
1064 print >> sys.stderr, "Error: bad dog!"
1065
1066As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +00001067evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001068
1069 print >> None, "Hello world"
1070
1071is equivalent to
1072
1073 print "Hello world"
1074
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001075Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001076
1077
1078Optional Collection of Cyclical Garbage
1079---------------------------------------
1080
1081Python is now equipped with a garbage collector that can hunt down
1082cyclical references between Python objects. It's no replacement for
1083reference counting; in fact, it depends on the reference counts being
1084correct, and decides that a set of objects belong to a cycle if all
1085their reference counts can be accounted for from their references to
1086each other. This devious scheme was first proposed by Eric Tiedemann,
1087and brought to implementation by Neil Schemenauer.
1088
1089There's a module "gc" that lets you control some parameters of the
1090garbage collection. There's also an option to the configure script
1091that lets you enable or disable the garbage collection. In 2.0b1,
1092it's on by default, so that we (hopefully) can collect decent user
1093experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +00001094performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001095off by default in the final 2.0 release.
1096
1097
1098Smaller Changes
1099---------------
1100
1101A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
1102map(None, seq1, seq2, ...) when the sequences have the same length;
1103i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
1104the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001105zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001106
1107sys.version_info is a tuple (major, minor, micro, level, serial).
1108
1109Dictionaries have an odd new method, setdefault(key, default).
1110dict.setdefault(key, default) returns dict[key] if it exists; if not,
1111it sets dict[key] to default and returns that value. Thus:
1112
1113 dict.setdefault(key, []).append(item)
1114
1115does the same work as this common idiom:
1116
1117 if not dict.has_key(key):
1118 dict[key] = []
1119 dict[key].append(item)
1120
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001121There are two new variants of SyntaxError that are raised for
1122indentation-related errors: IndentationError and TabError.
1123
1124Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1125escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001126
1127The limits on the size of expressions and file in Python source code
1128have been raised from 2**16 to 2**32. Previous versions of Python
1129were limited because the maximum argument size the Python VM accepted
1130was 2**16. This limited the size of object constructor expressions,
1131e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1132limit was raised thanks to a patch by Charles Waldman that effectively
1133fixes the problem. It is now much more likely that you will be
1134limited by available memory than by an arbitrary limit in Python.
1135
1136The interpreter's maximum recursion depth can be modified by Python
1137programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1138limit is the maximum number of recursive calls that can be made by
1139Python code. The limit exists to prevent infinite recursion from
1140overflowing the C stack and causing a core dump. The default value is
11411000. The maximum safe value for a particular platform can be found
1142by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001143
1144New Modules and Packages
1145------------------------
1146
1147atexit - for registering functions to be called when Python exits.
1148
1149imputil - Greg Stein's alternative API for writing custom import
1150hooks.
1151
1152pyexpat - an interface to the Expat XML parser, contributed by Paul
1153Prescod.
1154
1155xml - a new package with XML support code organized (so far) in three
1156subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1157would fill a volume. There's a special feature whereby a
1158user-installed package named _xmlplus overrides the standard
1159xmlpackage; this is intended to give the XML SIG a hook to distribute
1160backwards-compatible updates to the standard xml package.
1161
1162webbrowser - a platform-independent API to launch a web browser.
1163
1164
Guido van Rossume905e952000-09-05 12:42:46 +00001165Changed Modules
1166---------------
1167
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001168array -- new methods for array objects: count, extend, index, pop, and
1169remove
1170
1171binascii -- new functions b2a_hex and a2b_hex that convert between
1172binary data and its hex representation
1173
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001174calendar -- Many new functions that support features including control
1175over which day of the week is the first day, returning strings instead
1176of printing them. Also new symbolic constants for days of week,
1177e.g. MONDAY, ..., SUNDAY.
1178
1179cgi -- FieldStorage objects have a getvalue method that works like a
1180dictionary's get method and returns the value attribute of the object.
1181
1182ConfigParser -- The parser object has new methods has_option,
1183remove_section, remove_option, set, and write. They allow the module
1184to be used for writing config files as well as reading them.
1185
1186ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001187optionally support the RFC 959 REST command.
1188
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001189gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001190
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001191httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1192the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001193
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001194locale -- implement getdefaultlocale for Win32 and Macintosh
1195
1196marshal -- no longer dumps core when marshaling deeply nested or
1197recursive data structures
1198
1199os -- new functions isatty, seteuid, setegid, setreuid, setregid
1200
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001201os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1202support under Unix.
1203
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001204os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001205
1206os.path -- fix semantics of os.path.commonprefix
1207
1208smtplib -- support for sending very long messages
1209
1210socket -- new function getfqdn()
1211
1212readline -- new functions to read, write and truncate history files.
1213The readline section of the library reference manual contains an
1214example.
1215
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001216select -- add interface to poll system call
1217
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001218shutil -- new copyfileobj function
1219
1220SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1221HTTP server.
1222
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001223Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001224
1225urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001226e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001227
1228whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001229
1230
1231Obsolete Modules
1232----------------
1233
1234None. However note that 1.6 made a whole slew of modules obsolete:
1235stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1236poly, zmod, strop, util, whatsound.
1237
1238
1239Changed, New, Obsolete Tools
1240----------------------------
1241
Tim Peters8b092332000-09-05 20:15:25 +00001242None.
Guido van Rossume905e952000-09-05 12:42:46 +00001243
1244
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001245C-level Changes
1246---------------
1247
1248Several cleanup jobs were carried out throughout the source code.
1249
1250All C code was converted to ANSI C; we got rid of all uses of the
1251Py_PROTO() macro, which makes the header files a lot more readable.
1252
1253Most of the portability hacks were moved to a new header file,
1254pyport.h; several other new header files were added and some old
1255header files were removed, in an attempt to create a more rational set
1256of header files. (Few of these ever need to be included explicitly;
1257they are all included by Python.h.)
1258
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001259Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001260and Win64, especially for the new Intel Itanium processor. Mick also
1261added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001262
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001263The C APIs to return an object's size have been update to consistently
1264use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1265previous versions, the abstract interfaces used PyXXX_Length and the
1266concrete interfaces used PyXXX_Size. The old names,
1267e.g. PyObject_Length, are still available for backwards compatibility
1268at the API level, but are deprecated.
1269
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001270The PyOS_CheckStack function has been implemented on Windows by
1271Fredrik Lundh. It prevents Python from failing with a stack overflow
1272on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001273
1274The GC changes resulted in creation of two new slots on object,
1275tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001276the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001277
1278The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001279C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001280
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001281PyErr_Format has been updated to automatically calculate the size of
1282the buffer needed to hold the formatted result string. This change
1283prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001284
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001285New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001286
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001287PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1288that are the same as their non-Ex counterparts except they take an
1289extra flag argument that tells them to close the file when done.
1290
1291XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001292
Tim Peters8b092332000-09-05 20:15:25 +00001293
1294Windows Changes
1295---------------
1296
1297New popen2/popen3/peopen4 in os module (see Changed Modules above).
1298
1299os.popen is much more usable on Windows 95 and 98. See Microsoft
1300Knowledge Base article Q150956. The Win9x workaround described there
1301is implemented by the new w9xpopen.exe helper in the root of your
1302Python installation. Note that Python uses this internally; it is not
1303a standalone program.
1304
1305Administrator privileges are no longer required to install Python
1306on Windows NT or Windows 2000. If you have administrator privileges,
1307Python's registry info will be written under HKEY_LOCAL_MACHINE.
1308Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001309under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001310uses of Python, but will prevent some advanced uses from working
1311(for example, running a Python script as an NT service, or possibly
1312from CGI).
1313
1314[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1315installer; instead, it installs the needed Tcl/Tk files directly in the
1316Python directory. If you already have a Tcl/Tk installation, this
1317wastes some disk space (about 4 Megs) but avoids problems with
1318conflicting Tcl/Tk installations, and makes it much easier for Python
1319to ensure that Tcl/Tk can find all its files.
1320
1321[This was new in 1.6] The Windows installer now installs by default in
1322\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1323
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001324
1325Updates to the changes between 1.5.2 and 1.6
1326--------------------------------------------
1327
1328The 1.6 NEWS file can't be changed after the release is done, so here
1329is some late-breaking news:
1330
1331New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1332and changes to getlocale() and setlocale().
1333
1334The new module is now enabled per default.
1335
1336It is not true that the encodings codecs cannot be used for normal
1337strings: the string.encode() (which is also present on 8-bit strings
1338!) allows using them for 8-bit strings too, e.g. to convert files from
1339cp1252 (Windows) to latin-1 or vice-versa.
1340
1341Japanese codecs are available from Tamito KAJIYAMA:
1342http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1343
1344
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001345======================================================================