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Tim Petersd7b5e882001-01-25 03:36:26 +00001What's New in Python 2.1 alpha 2?
2=================================
Tim Peters40ead762001-01-27 05:35:26 +00003
Tim Petersd7b5e882001-01-25 03:36:26 +00004Core language, builtins, and interpreter
5
Tim Peters40ead762001-01-27 05:35:26 +00006- repr(string) is easier to read, now using hex escapes instead of octal,
7 and using \t, \n and \r instead of \011, \012 and \015 (respectively):
8
9 >>> "\texample \r\n" + chr(0) + chr(255)
10 '\texample \r\n\x00\xff' # in 2.1
11 '\011example \015\012\000\377' # in 2.0
12
Tim Petersd7b5e882001-01-25 03:36:26 +000013
14Standard library
15
16- random.py is now self-contained, and offers all the functionality of
17 the now-deprecated whrandom.py. See the docs for details. random.py
18 also supports new functions getstate() and setstate(), for saving
Tim Petersd52269b2001-01-25 06:23:18 +000019 and restoring the internal state of the generator; and jumpahead(n),
20 for quickly forcing the internal state to be the same as if n calls to
21 random() had been made. The latter is particularly useful for multi-
22 threaded programs, creating one instance of the random.Random() class for
23 each thread, then using .jumpahead() to force each instance to use a
24 non-overlapping segment of the full period.
Tim Petersd7b5e882001-01-25 03:36:26 +000025
26
Tim Petersa3a3a032000-11-30 05:22:44 +000027What's New in Python 2.1 alpha 1?
28=================================
29
30Core language, builtins, and interpreter
31
Marc-André Lemburgebb195b2001-01-20 10:34:52 +000032- There is a new Unicode companion to the PyObject_Str() API
33 called PyObject_Unicode(). It behaves in the same way as the
34 former, but assures that the returned value is an Unicode object
35 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +000036
Guido van Rossumf98eda02001-01-17 15:54:45 +000037- The comparison operators support "rich comparison overloading" (PEP
38 207). C extension types can provide a rich comparison function in
39 the new tp_richcompare slot in the type object. The cmp() function
40 and the C function PyObject_Compare() first try the new rich
41 comparison operators before trying the old 3-way comparison. There
42 is also a new C API PyObject_RichCompare() (which also falls back on
43 the old 3-way comparison, but does not constrain the outcome of the
44 rich comparison to a Boolean result).
45
46 The rich comparison function takes two objects (at least one of
47 which is guaranteed to have the type that provided the function) and
48 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
49 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
50 object, which may be NotImplemented (in which case the tp_compare
51 slot function is used as a fallback, if defined).
52
53 Classes can overload individual comparison operators by defining one
54 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +000055 __ge__. There are no explicit "reflected argument" versions of
56 these; instead, __lt__ and __gt__ are each other's reflection,
57 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
58 reflection (similar at the C level). No other implications are
59 made; in particular, Python does not assume that == is the Boolean
60 inverse of !=, or that < is the Boolean inverse of >=. This makes
61 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +000062
63 Classes or types that want to implement (in)equality tests but not
64 the ordering operators (i.e. unordered types) should implement ==
65 and !=, and raise an error for the ordering operators.
66
Guido van Rossuma88479f2001-01-18 14:28:08 +000067 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +000068 Boolean; e.g. a matrix type might want to return a matrix of bits
69 for A < B, giving elementwise comparisons. Such types should ensure
70 that any interpretation of their value in a Boolean context raises
71 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
72 at the C level) to always raise an exception.
73
Guido van Rossuma88479f2001-01-18 14:28:08 +000074- Complex numbers use rich comparisons to define == and != but raise
75 an exception for <, <=, > and >=. Unfortunately, this also means
76 that cmp() of two complex numbers raises an exception when the two
77 numbers differ. Since it is not mathematically meaningful to compare
78 complex numbers except for equality, I hope that this doesn't break
79 too much code.
80
Barry Warsaw573b5412001-01-15 20:43:18 +000081- Functions and methods now support getting and setting arbitrarily
82 named attributes (PEP 232). Functions have a new __dict__
83 (a.k.a. func_dict) which hold the function attributes. Methods get
84 and set attributes on their underlying im_func. It is a TypeError
85 to set an attribute on a bound method.
86
Guido van Rossum051e3352001-01-15 19:11:10 +000087- The xrange() object implementation has been improved so that
88 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
89 limitation that in this case len(xrange(sys.maxint)) can't be
90 calculated, but the common idiom "for i in xrange(sys.maxint)" will
91 work fine as long as the index i doesn't actually reach 2**31.
92 (Python uses regular ints for sequence and string indices; fixing
93 that is much more work.)
94
Guido van Rossum1cc8f832001-01-12 16:25:08 +000095- Two changes to from...import:
96
97 1) "from M import X" now works even if M is not a real module; it's
98 basically a getattr() operation with AttributeError exceptions
99 changed into ImportError.
100
101 2) "from M import *" now looks for M.__all__ to decide which names to
102 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
103 filters out names starting with '_' as before. Whether or not
104 __all__ exists, there's no restriction on the type of M.
105
Guido van Rossumf61f1662001-01-10 20:13:55 +0000106- File objects have a new method, xreadlines(). This is the fastest
107 way to iterate over all lines in a file:
108
109 for line in file.xreadlines():
110 ...do something to line...
111
112 See the xreadlines module (mentioned below) for how to do this for
113 other file-like objects.
114
115- Even if you don't use file.xreadlines(), you may expect a speedup on
116 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +0000117 quite a bit in platform-specific ways: on systems (like Linux) that
118 support flockfile(), getc_unlocked(), and funlockfile(), those are
119 used by default. On systems (like Windows) without getc_unlocked(),
120 a complicated (but still thread-safe) method using fgets() is used by
121 default.
122
Tim Petersd52269b2001-01-25 06:23:18 +0000123 You can force use of the fgets() method by #define'ing
124 USE_FGETS_IN_GETLINE at build time (it may be faster than
Tim Petersf29b64d2001-01-15 06:33:19 +0000125 getc_unlocked()).
126
Tim Petersd52269b2001-01-25 06:23:18 +0000127 You can force fgets() not to be used by #define'ing
128 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
Tim Petersf29b64d2001-01-15 06:33:19 +0000129 test_bufio.py fails -- and let us know if it does!).
130
131- In addition, the fileinput module, while still slower than the other
132 methods on most platforms, has been sped up too, by using
133 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000134
135- Support for run-time warnings has been added, including a new
136 command line option (-W) to specify the disposition of warnings.
137 See the description of the warnings module below.
138
139- Extensive changes have been made to the coercion code. This mostly
140 affects extension modules (which can now implement mixed-type
141 numerical operators without having to use coercion), but
142 occasionally, in boundary cases the coercion semantics have changed
143 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000144 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000145 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000146 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000147
Guido van Rossumf98eda02001-01-17 15:54:45 +0000148- In connection with the coercion changes, a new built-in singleton
149 object, NotImplemented is defined. This can be returned for
150 operations that wish to indicate they are not implemented for a
151 particular combination of arguments. From C, this is
152 Py_NotImplemented.
153
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000154- The interpreter accepts now bytecode files on the command line even
155 if they do not have a .pyc or .pyo extension. On Linux, after executing
156
157 echo ':pyc:M::\x87\xc6\x0d\x0a::/usr/local/bin/python:' > /proc/sys/fs/binfmt_misc/register
158
159 any byte code file can be used as an executable (i.e. as an argument
160 to execve(2)).
161
Tim Peters9940b802000-12-01 07:59:35 +0000162- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000163 character. In 1.6 and earlier, they never produced a sign,
164 and raised an error if the value of the long was too large
165 to fit in a Python int. In 2.0, they produced a sign if and
166 only if too large to fit in an int. This was inconsistent
167 across platforms (because the size of an int varies across
168 platforms), and inconsistent with hex() and oct(). Example:
169
170 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000171 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000172 'ffffffbe' # in 2.0 and before, on 32-bit machines
173 >>> hex(-0x42L)
174 '-0x42L' # in all versions of Python
175
Tim Peters9940b802000-12-01 07:59:35 +0000176 The behavior of %d formats for negative Python longs remains
177 the same as in 2.0 (although in 1.6 and before, they raised
178 an error if the long didn't fit in a Python int).
179
180 %u formats don't make sense for Python longs, but are allowed
181 and treated the same as %d in 2.1. In 2.0, a negative long
182 formatted via %u produced a sign if and only if too large to
183 fit in an int. In 1.6 and earlier, a negative long formatted
184 via %u raised an error if it was too big to fit in an int.
185
Guido van Rossum3661d392000-12-12 22:10:31 +0000186- Dictionary objects have an odd new method, popitem(). This removes
187 an arbitrary item from the dictionary and returns it (in the form of
188 a (key, value) pair). This can be useful for algorithms that use a
189 dictionary as a bag of "to do" items and repeatedly need to pick one
190 item. Such algorithms normally end up running in quadratic time;
191 using popitem() they can usually be made to run in linear time.
192
Tim Peters36cdad12000-12-29 02:06:45 +0000193Standard library
194
Thomas Woutersfe385252001-01-19 23:16:56 +0000195- In the time module, the time argument to the functions strftime,
196 localtime, gmtime, asctime and ctime is now optional, defaulting to
197 the current time (in the local timezone).
198
Guido van Rossumda91f222001-01-15 16:36:08 +0000199- The ftplib module now defaults to passive mode, which is deemed a
200 more useful default given that clients are often inside firewalls
201 these days. Note that this could break if ftplib is used to connect
202 to a *server* that is inside a firewall, from outside; this is
203 expected to be a very rare situation. To fix that, you can call
204 ftp.set_pasv(0).
205
Martin v. Löwis10a27872001-01-13 09:54:41 +0000206- The module site now treats .pth files not only for path configuration,
207 but also supports extensions to the initialization code: Lines starting
208 with import are executed.
209
Guido van Rossumf61f1662001-01-10 20:13:55 +0000210- There's a new module, warnings, which implements a mechanism for
211 issuing and filtering warnings. There are some new built-in
212 exceptions that serve as warning categories, and a new command line
213 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
214 turns warnings into errors). warnings.warn(message[, category])
215 issues a warning message; this can also be called from C as
216 PyErr_Warn(category, message).
217
218- A new module xreadlines was added. This exports a single factory
219 function, xreadlines(). The intention is that this code is the
220 absolutely fastest way to iterate over all lines in an open
221 file(-like) object:
222
223 import xreadlines
224 for line in xreadlines.xreadlines(file):
225 ...do something to line...
226
227 This is equivalent to the previous the speed record holder using
228 file.readlines(sizehint). Note that if file is a real file object
229 (as opposed to a file-like object), this is equivalent:
230
231 for line in file.xreadlines():
232 ...do something to line...
233
Tim Peters36cdad12000-12-29 02:06:45 +0000234- The bisect module has new functions bisect_left, insort_left,
235 bisect_right and insort_right. The old names bisect and insort
236 are now aliases for bisect_right and insort_right. XXX_right
237 and XXX_left methods differ in what happens when the new element
238 compares equal to one or more elements already in the list: the
239 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000240 right. Code that doesn't care where equal elements end up should
241 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000242
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000243- The new curses.panel module wraps the panel library that forms part
244 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
245
Guido van Rossumf61f1662001-01-10 20:13:55 +0000246- The SocketServer module now sets the allow_reuse_address flag by
247 default in the TCPServer class.
248
249- A new function, sys._getframe(), returns the stack frame pointer of
250 the caller. This is intended only as a building block for
251 higher-level mechanisms such as string interpolation.
252
253Build issues
254
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000255- For Unix (and Unix-compatible) builds, configuration and building of
256 extension modules is now greatly automated. Rather than having to
257 edit the Modules/Setup file to indicate which modules should be
258 built and where their include files and libraries are, a
259 distutils-based setup.py script now takes care of building most
260 extension modules. All extension modules built this way are built
261 as shared libraries. Only a few modules that must be linked
262 statically are still listed in the Setup file; you won't need to
263 edit their configuration.
264
265- Python should now build out of the box on Cygwin. If it doesn't,
266 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000267
268- Python now always uses its own (renamed) implementation of getopt()
269 -- there's too much variation among C library getopt()
270 implementations.
271
272- C++ compilers are better supported; the CXX macro is always set to a
273 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000274
Tim Petersd92dfe02000-12-12 01:18:41 +0000275Windows changes
276
277- select module: By default under Windows, a select() call
278 can specify no more than 64 sockets. Python now boosts
279 this Microsoft default to 512. If you need even more than
280 that, see the MS docs (you'll need to #define FD_SETSIZE
281 and recompile Python from source).
282
Guido van Rossumf61f1662001-01-10 20:13:55 +0000283- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
284 subdirectory is no more!
285
Tim Petersa3a3a032000-11-30 05:22:44 +0000286
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000287What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000288=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000289
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000290Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000291changes are in the file HISTORY. If you are making the jump directly
292from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
293HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000294
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000295Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
296the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
297http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000298
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000299--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000300
301======================================================================
302
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000303What's new in 2.0 (since release candidate 1)?
304==============================================
305
306Standard library
307
308- The copy_reg module was modified to clarify its intended use: to
309 register pickle support for extension types, not for classes.
310 pickle() will raise a TypeError if it is passed a class.
311
312- Fixed a bug in gettext's "normalize and expand" code that prevented
313 it from finding an existing .mo file.
314
315- Restored support for HTTP/0.9 servers in httplib.
316
Tim Peters989b7b92000-10-16 20:24:53 +0000317- The math module was changed to stop raising OverflowError in case of
318 underflow, and return 0 instead in underflow cases. Whether Python
319 used to raise OverflowError in case of underflow was platform-
320 dependent (it did when the platform math library set errno to ERANGE
321 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000322
323- Fixed a bug in StringIO that occurred when the file position was not
324 at the end of the file and write() was called with enough data to
325 extend past the end of the file.
326
327- Fixed a bug that caused Tkinter error messages to get lost on
328 Windows. The bug was fixed by replacing direct use of
329 interp->result with Tcl_GetStringResult(interp).
330
331- Fixed bug in urllib2 that caused it to fail when it received an HTTP
332 redirect response.
333
334- Several changes were made to distutils: Some debugging code was
335 removed from util. Fixed the installer used when an external zip
336 program (like WinZip) is not found; the source code for this
337 installer is in Misc/distutils. check_lib() was modified to behave
338 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
339 test for whether installed modules are on sys.path was changed to
340 use both normcase() and normpath().
341
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000342- Several minor bugs were fixed in the xml package (the minidom,
343 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000344
345- The regression test driver (regrtest.py) behavior when invoked with
346 -l changed: It now reports a count of objects that are recognized as
347 garbage but not freed by the garbage collector.
348
Tim Peters989b7b92000-10-16 20:24:53 +0000349- The regression test for the math module was changed to test
350 exceptional behavior when the test is run in verbose mode. Python
351 cannot yet guarantee consistent exception behavior across platforms,
352 so the exception part of test_math is run only in verbose mode, and
353 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000354
355Internals
356
357- PyOS_CheckStack() has been disabled on Win64, where it caused
358 test_sre to fail.
359
360Build issues
361
362- Changed compiler flags, so that gcc is always invoked with -Wall and
363 -Wstrict-prototypes. Users compiling Python with GCC should see
364 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000365 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000366 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000367
Tim Petersa3a3a032000-11-30 05:22:44 +0000368- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000369
370Tools and other miscellany
371
372- The compiler in Tools/compiler was updated to support the new
373 language features introduced in 2.0: extended print statement, list
374 comprehensions, and augmented assignments. The new compiler should
375 also be backwards compatible with Python 1.5.2; the compiler will
376 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000377 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000378
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000379What's new in 2.0 release candidate 1 (since beta 2)?
380=====================================================
381
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000382What is release candidate 1?
383
384We believe that release candidate 1 will fix all known bugs that we
385intend to fix for the 2.0 final release. This release should be a bit
386more stable than the previous betas. We would like to see even more
387widespread testing before the final release, so we are producing this
388release candidate. The final release will be exactly the same unless
389any show-stopping (or brown bag) bugs are found by testers of the
390release candidate.
391
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000392All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000393to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000394
395Core language, builtins, and interpreter
396
397- A bug that caused crashes when __coerce__ was used with augmented
398 assignment, e.g. +=, was fixed.
399
400- Raise ZeroDivisionError when raising zero to a negative number,
401 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
402 power operator and the result of math.pow(0.0, -2.0) will vary by
403 platform. On Linux, it raises a ValueError.
404
405- A bug in Unicode string interpolation was fixed that occasionally
406 caused errors with formats including "%%". For example, the
407 following expression "%% %s" % u"abc" no longer raises a TypeError.
408
409- Compilation of deeply nested expressions raises MemoryError instead
410 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
411
412- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
413 rendering them useless. They are now written in binary mode again.
414
415Standard library
416
417- Keyword arguments are now accepted for most pattern and match object
418 methods in SRE, the standard regular expression engine.
419
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000420- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000421 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000422
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000423- Several bugs in the Unicode handling and error handling in _tkinter
424 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000425
426- Fix memory management errors in Merge() and Tkapp_Call() routines.
427
428- Several changes were made to cStringIO to make it compatible with
429 the file-like object interface and with StringIO. If operations are
430 performed on a closed object, an exception is raised. The truncate
431 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000432 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000433
434- There were many changes made to the linuxaudiodev module and its
435 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000436 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000437
438 Note that this module is named poorly, because it should work
439 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000440 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000441
442 The module now raises exceptions when errors occur instead of
443 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
444 audio) and defines a getptr() method that calls the
445 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
446
447- The library_version attribute, introduced in an earlier beta, was
448 removed because it can not be supported with early versions of the C
449 readline library, which provides no way to determine the version at
450 compile-time.
451
452- The binascii module is now enabled on Win64.
453
Tim Peters46446d62000-10-09 21:19:31 +0000454- tokenize.py no longer suffers "recursion depth" errors when parsing
455 programs with very long string literals.
456
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000457Internals
458
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000459- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000460 which is called when the interpreter starts up to determine where
461 the standard library is installed. These vulnerabilities affect all
462 previous versions of Python and can be exploited by setting very
463 long values for PYTHONHOME or argv[0]. The risk is greatest for a
464 setuid Python script, although use of the wrapper in
465 Misc/setuid-prog.c will eliminate the vulnerability.
466
467- Fixed garbage collection bugs in instance creation that were
468 triggered when errors occurred during initialization. The solution,
469 applied in cPickle and in PyInstance_New(), is to call
470 PyObject_GC_Init() after the initialization of the object's
471 container attributes is complete.
472
473- pyexpat adds definitions of PyModule_AddStringConstant and
474 PyModule_AddObject if the Python version is less than 2.0, which
475 provides compatibility with PyXML on Python 1.5.2.
476
477- If the platform has a bogus definition for LONG_BIT (the number of
478 bits in a long), an error will be reported at compile time.
479
480- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
481 collection crashes and possibly other, unreported crashes.
482
483- Fixed a memory leak in _PyUnicode_Fini().
484
485Build issues
486
487- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000488 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000489 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000490
491- The mmap.PAGESIZE constant is now initialized using sysconf when
492 possible, which eliminates a dependency on -lucb for Reliant UNIX.
493
494- The md5 file should now compile on all platforms.
495
496- The select module now compiles on platforms that do not define
497 POLLRDNORM and related constants.
498
499- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000500 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000501
Jeremy Hylton10921202000-10-09 18:34:12 +0000502- BeOS: A number of changes were made to the build and installation
503 process. ar-fake now operates on a directory of object files.
504 dl_export.h is gone, and its macros now appear on the mwcc command
505 line during build on PPC BeOS.
506
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000507- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000508 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000509
510- Cygwin: Support for shared libraries, Tkinter, and sockets.
511
512- SunOS 4.1.4_JL: Fix test for directory existence in configure.
513
514Tools and other miscellany
515
516- Removed debugging prints from main used with freeze.
517
Tim Peters46446d62000-10-09 21:19:31 +0000518- IDLE auto-indent no longer crashes when it encounters Unicode
519 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000520
521What's new in 2.0 beta 2 (since beta 1)?
522========================================
523
524Core language, builtins, and interpreter
525
Tim Peters482c0212000-09-26 06:33:09 +0000526- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000527 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000528
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000529- Add -h and -V command line options to print the usage message and
530 Python version number and exit immediately.
531
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000532- eval() and exec accept Unicode objects as code parameters.
533
534- getattr() and setattr() now also accept Unicode objects for the
535 attribute name, which are converted to strings using the default
536 encoding before lookup.
537
538- Multiplication on string and Unicode now does proper bounds
539 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
540 string is too long."
541
542- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000543 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000544
Jeremy Hylton1b618592000-09-26 05:32:36 +0000545
546Standard library and extensions
547
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000548- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000549 argument checking; it still takes no arguments.
550
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000551- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000552
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000553- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000554
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000555- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000556
557- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000558 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000559
560- copy: Copy Unicode objects atomically.
561
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000562- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000563
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000564- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000565
Fred Drake67233bc2000-09-26 16:40:27 +0000566- dbm: Add get() and setdefault() methods to dbm object. Add constant
567 `library' to module that names the library used. Added doc strings
568 and method names to error messages. Uses configure to determine
569 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
570 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000571
572- distutils: Update to version 0.9.3.
573
574- dl: Add several dl.RTLD_ constants.
575
576- fpectl: Now supported on FreeBSD.
577
578- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
579 found by the collector will be saved in gc.garbage. This is useful
580 for debugging a program that creates reference cycles.
581
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000582- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000583 of HTTP class. Do not close socket on zero-length response. Do not
584 crash when server sends invalid content-length header.
585
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000586- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000587
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000588- marshal: When reading a short, sign-extend on platforms where shorts
589 are bigger than 16 bits. When reading a long, repair the unportable
590 sign extension that was being done for 64-bit machines. (It assumed
591 that signed right shift sign-extends.)
592
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000593- operator: Add contains(), invert(), __invert__() as aliases for
594 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000595
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000596- os: Add support for popen2() and popen3() on all platforms where
597 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000598
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000599- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000600 clicking on a file in Explorer (or passing the file name to the
601 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000602
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000603- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000604 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000605
606- pickle: Now raises ValueError when an invalid pickle that contains
607 a non-string repr where a string repr was expected. This behavior
608 matches cPickle.
609
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000610- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000611
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000612- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000613
614- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000615 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000616 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000617
618- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000619 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000620
621- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000622 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000623 few cycles during startup since the first call to
624 setdefaultencoding() will initialize the codec registry and the
625 encodings package.
626
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000627- socket: Support for size hint in readlines() method of object returned
628 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000629
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000630- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000631 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000632 is followed by whitespace.
633
Tim Petersa3a3a032000-11-30 05:22:44 +0000634- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000635
636- struct: Check ranges for bytes and shorts.
637
638- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000639 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000640
641- Tkinter: Image objects are now guaranteed to have unique ids. Set
642 event.delta to zero if Tk version doesn't support mousewheel.
643 Removed some debugging prints.
644
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000645- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000646
Fred Drake67233bc2000-09-26 16:40:27 +0000647- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000648 which works around a bug in Norton AntiVirus 2000 that leads directly
649 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000650
651- xml: New version detection code allows PyXML to override standard
652 XML package if PyXML version is greater than 0.6.1.
653
Fred Drake64bb3802000-09-26 16:21:35 +0000654- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
655 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
656 tree only for nodes which are sufficiently interesting to a specific
657 application. Does not provide the HTML-specific extensions. Still
658 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000659
Fred Drake64bb3802000-09-26 16:21:35 +0000660- xml.sax: SAX 2 support for Python, including all the handler
661 interfaces needed to process XML 1.0 compliant XML. Some
662 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000663
Fred Drake64bb3802000-09-26 16:21:35 +0000664- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
665 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000666
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000667
Jeremy Hylton1b618592000-09-26 05:32:36 +0000668C API
669
670- Add three new convenience functions for module initialization --
671 PyModule_AddObject(), PyModule_AddIntConstant(), and
672 PyModule_AddStringConstant().
673
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000674- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000675 removed and add #error to Python.h if NULL isn't defined after
676 #include of stdio.h.
677
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000678- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000679 backwards compatibility (at the source level) with old extensions.
680
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000681- A wrapper API was added for signal() and sigaction(). Instead of
682 either function, always use PyOS_getsig() to get a signal handler
683 and PyOS_setsig() to set one. A new convenience typedef
684 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000685
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000686- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000687 internal data buffer and size of a string object -- or the default
688 encoded version of a Unicode object.
689
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000690- PyString_Size() and PyString_AsString() accept Unicode objects.
691
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000692- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000693 exists). INT_MAX and LONG_MAX will always be defined, even if
694 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000695
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000696- PyFloat_FromString takes a second argument, pend, that was
697 effectively useless. It is now officially useless but preserved for
698 backwards compatibility. If the pend argument is not NULL, *pend is
699 set to NULL.
700
701- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
702 for the attribute name. See note on getattr() above.
703
704- A few bug fixes to argument processing for Unicode.
705 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
706 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
707 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000708 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000709
710- Py_BuildValue accepts B format (for bgen-generated code).
711
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000712
Jeremy Hylton1b618592000-09-26 05:32:36 +0000713Internals
714
715- On Unix, fix code for finding Python installation directory so that
716 it works when argv[0] is a relative path.
717
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000718- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000719 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000720 rather than by generating a copy of the object.
721
Tim Peters482c0212000-09-26 06:33:09 +0000722- Several of the internal Unicode tables are much smaller now, and
723 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000724
Jeremy Hylton97693b02000-09-26 17:42:51 +0000725- In the garbage collector: Fixed bug in collection of tuples. Fixed
726 bug that caused some instances to be removed from the container set
727 while they were still live. Fixed parsing in gc.set_debug() for
728 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000729
730- Fixed refcount problem in instance deallocation that only occurred
731 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
732
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000733- On Windows, getpythonregpath is now protected against null data in
734 registry key.
735
736- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000737 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000738
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000739
Jeremy Hylton1b618592000-09-26 05:32:36 +0000740Build and platform-specific issues
741
742- Better support of GNU Pth via --with-pth configure option.
743
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000744- Python/C API now properly exposed to dynamically-loaded extension
745 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000746
747- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
748 Don't define MS_SYNC to be zero when it is undefined. Added missing
749 prototypes in posixmodule.c.
750
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000751- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000752 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000753
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000754- Fix largefile support on older NetBSD systems and OpenBSD by adding
755 define for TELL64.
756
757
758Tools and other miscellany
759
760- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
761
762- freeze: The modulefinder now works with 2.0 opcodes.
763
Tim Petersa3a3a032000-11-30 05:22:44 +0000764- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000765 Move hackery of sys.argv until after the Tk instance has been
766 created, which allows the application-specific Tkinter
767 initialization to be executed if present; also pass an explicit
768 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000769
Jeremy Hylton1b618592000-09-26 05:32:36 +0000770
771What's new in 2.0 beta 1?
772=========================
773
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000774Source Incompatibilities
775------------------------
776
777None. Note that 1.6 introduced several incompatibilities with 1.5.2,
778such as single-argument append(), connect() and bind(), and changes to
779str(long) and repr(float).
780
781
782Binary Incompatibilities
783------------------------
784
785- Third party extensions built for Python 1.5.x or 1.6 cannot be used
786with Python 2.0; these extensions will have to be rebuilt for Python
7872.0.
788
789- On Windows, attempting to import a third party extension built for
790Python 1.5.x or 1.6 results in an immediate crash; there's not much we
791can do about this. Check your PYTHONPATH environment variable!
792
793- Python bytecode files (*.pyc and *.pyo) are not compatible between
794releases.
795
796
797Overview of Changes Since 1.6
798-----------------------------
799
800There are many new modules (including brand new XML support through
801the xml package, and i18n support through the gettext module); a list
802of all new modules is included below. Lots of bugs have been fixed.
803
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000804The process for making major new changes to the language has changed
805since Python 1.6. Enhancements must now be documented by a Python
806Enhancement Proposal (PEP) before they can be accepted.
807
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000808There are several important syntax enhancements, described in more
809detail below:
810
811 - Augmented assignment, e.g. x += 1
812
813 - List comprehensions, e.g. [x**2 for x in range(10)]
814
815 - Extended import statement, e.g. import Module as Name
816
817 - Extended print statement, e.g. print >> file, "Hello"
818
819Other important changes:
820
821 - Optional collection of cyclical garbage
822
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000823Python Enhancement Proposal (PEP)
824---------------------------------
825
826PEP stands for Python Enhancement Proposal. A PEP is a design
827document providing information to the Python community, or describing
828a new feature for Python. The PEP should provide a concise technical
829specification of the feature and a rationale for the feature.
830
831We intend PEPs to be the primary mechanisms for proposing new
832features, for collecting community input on an issue, and for
833documenting the design decisions that have gone into Python. The PEP
834author is responsible for building consensus within the community and
835documenting dissenting opinions.
836
837The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000838
839Augmented Assignment
840--------------------
841
842This must have been the most-requested feature of the past years!
843Eleven new assignment operators were added:
844
Guido van Rossume905e952000-09-05 12:42:46 +0000845 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000846
847For example,
848
849 A += B
850
851is similar to
852
853 A = A + B
854
855except that A is evaluated only once (relevant when A is something
856like dict[index].attr).
857
858However, if A is a mutable object, A may be modified in place. Thus,
859if A is a number or a string, A += B has the same effect as A = A+B
860(except A is only evaluated once); but if a is a list, A += B has the
861same effect as A.extend(B)!
862
863Classes and built-in object types can override the new operators in
864order to implement the in-place behavior; the not-in-place behavior is
865used automatically as a fallback when an object doesn't implement the
866in-place behavior. For classes, the method name is derived from the
867method name for the corresponding not-in-place operator by inserting
868an 'i' in front of the name, e.g. __iadd__ implements in-place
869__add__.
870
871Augmented assignment was implemented by Thomas Wouters.
872
873
874List Comprehensions
875-------------------
876
877This is a flexible new notation for lists whose elements are computed
878from another list (or lists). The simplest form is:
879
880 [<expression> for <variable> in <sequence>]
881
Guido van Rossum56db0952000-09-06 23:34:25 +0000882For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000883This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000884
885You can also add a condition:
886
887 [<expression> for <variable> in <sequence> if <condition>]
888
889For example, [w for w in words if w == w.lower()] would yield the list
890of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000891than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000892
893You can also have nested for loops and more than one 'if' clause. For
894example, here's a function that flattens a sequence of sequences::
895
896 def flatten(seq):
897 return [x for subseq in seq for x in subseq]
898
899 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
900
901This prints
902
903 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
904
905List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000906Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000907
908
909Extended Import Statement
910-------------------------
911
912Many people have asked for a way to import a module under a different
913name. This can be accomplished like this:
914
915 import foo
916 bar = foo
917 del foo
918
919but this common idiom gets old quickly. A simple extension of the
920import statement now allows this to be written as follows:
921
922 import foo as bar
923
924There's also a variant for 'from ... import':
925
926 from foo import bar as spam
927
928This also works with packages; e.g. you can write this:
929
930 import test.regrtest as regrtest
931
932Note that 'as' is not a new keyword -- it is recognized only in this
933context (this is only possible because the syntax for the import
934statement doesn't involve expressions).
935
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000936Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000937
938
939Extended Print Statement
940------------------------
941
942Easily the most controversial new feature, this extension to the print
943statement adds an option to make the output go to a different file
944than the default sys.stdout.
945
946For example, to write an error message to sys.stderr, you can now
947write:
948
949 print >> sys.stderr, "Error: bad dog!"
950
951As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +0000952evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000953
954 print >> None, "Hello world"
955
956is equivalent to
957
958 print "Hello world"
959
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000960Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000961
962
963Optional Collection of Cyclical Garbage
964---------------------------------------
965
966Python is now equipped with a garbage collector that can hunt down
967cyclical references between Python objects. It's no replacement for
968reference counting; in fact, it depends on the reference counts being
969correct, and decides that a set of objects belong to a cycle if all
970their reference counts can be accounted for from their references to
971each other. This devious scheme was first proposed by Eric Tiedemann,
972and brought to implementation by Neil Schemenauer.
973
974There's a module "gc" that lets you control some parameters of the
975garbage collection. There's also an option to the configure script
976that lets you enable or disable the garbage collection. In 2.0b1,
977it's on by default, so that we (hopefully) can collect decent user
978experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +0000979performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000980off by default in the final 2.0 release.
981
982
983Smaller Changes
984---------------
985
986A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
987map(None, seq1, seq2, ...) when the sequences have the same length;
988i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
989the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000990zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000991
992sys.version_info is a tuple (major, minor, micro, level, serial).
993
994Dictionaries have an odd new method, setdefault(key, default).
995dict.setdefault(key, default) returns dict[key] if it exists; if not,
996it sets dict[key] to default and returns that value. Thus:
997
998 dict.setdefault(key, []).append(item)
999
1000does the same work as this common idiom:
1001
1002 if not dict.has_key(key):
1003 dict[key] = []
1004 dict[key].append(item)
1005
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001006There are two new variants of SyntaxError that are raised for
1007indentation-related errors: IndentationError and TabError.
1008
1009Changed \x to consume exactly two hex digits; see PEP 223. Added \U
1010escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001011
1012The limits on the size of expressions and file in Python source code
1013have been raised from 2**16 to 2**32. Previous versions of Python
1014were limited because the maximum argument size the Python VM accepted
1015was 2**16. This limited the size of object constructor expressions,
1016e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
1017limit was raised thanks to a patch by Charles Waldman that effectively
1018fixes the problem. It is now much more likely that you will be
1019limited by available memory than by an arbitrary limit in Python.
1020
1021The interpreter's maximum recursion depth can be modified by Python
1022programs using sys.getrecursionlimit and sys.setrecursionlimit. This
1023limit is the maximum number of recursive calls that can be made by
1024Python code. The limit exists to prevent infinite recursion from
1025overflowing the C stack and causing a core dump. The default value is
10261000. The maximum safe value for a particular platform can be found
1027by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001028
1029New Modules and Packages
1030------------------------
1031
1032atexit - for registering functions to be called when Python exits.
1033
1034imputil - Greg Stein's alternative API for writing custom import
1035hooks.
1036
1037pyexpat - an interface to the Expat XML parser, contributed by Paul
1038Prescod.
1039
1040xml - a new package with XML support code organized (so far) in three
1041subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1042would fill a volume. There's a special feature whereby a
1043user-installed package named _xmlplus overrides the standard
1044xmlpackage; this is intended to give the XML SIG a hook to distribute
1045backwards-compatible updates to the standard xml package.
1046
1047webbrowser - a platform-independent API to launch a web browser.
1048
1049
Guido van Rossume905e952000-09-05 12:42:46 +00001050Changed Modules
1051---------------
1052
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001053array -- new methods for array objects: count, extend, index, pop, and
1054remove
1055
1056binascii -- new functions b2a_hex and a2b_hex that convert between
1057binary data and its hex representation
1058
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001059calendar -- Many new functions that support features including control
1060over which day of the week is the first day, returning strings instead
1061of printing them. Also new symbolic constants for days of week,
1062e.g. MONDAY, ..., SUNDAY.
1063
1064cgi -- FieldStorage objects have a getvalue method that works like a
1065dictionary's get method and returns the value attribute of the object.
1066
1067ConfigParser -- The parser object has new methods has_option,
1068remove_section, remove_option, set, and write. They allow the module
1069to be used for writing config files as well as reading them.
1070
1071ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001072optionally support the RFC 959 REST command.
1073
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001074gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001075
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001076httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1077the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001078
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001079locale -- implement getdefaultlocale for Win32 and Macintosh
1080
1081marshal -- no longer dumps core when marshaling deeply nested or
1082recursive data structures
1083
1084os -- new functions isatty, seteuid, setegid, setreuid, setregid
1085
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001086os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1087support under Unix.
1088
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001089os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001090
1091os.path -- fix semantics of os.path.commonprefix
1092
1093smtplib -- support for sending very long messages
1094
1095socket -- new function getfqdn()
1096
1097readline -- new functions to read, write and truncate history files.
1098The readline section of the library reference manual contains an
1099example.
1100
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001101select -- add interface to poll system call
1102
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001103shutil -- new copyfileobj function
1104
1105SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1106HTTP server.
1107
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001108Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001109
1110urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001111e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001112
1113whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001114
1115
1116Obsolete Modules
1117----------------
1118
1119None. However note that 1.6 made a whole slew of modules obsolete:
1120stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1121poly, zmod, strop, util, whatsound.
1122
1123
1124Changed, New, Obsolete Tools
1125----------------------------
1126
Tim Peters8b092332000-09-05 20:15:25 +00001127None.
Guido van Rossume905e952000-09-05 12:42:46 +00001128
1129
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001130C-level Changes
1131---------------
1132
1133Several cleanup jobs were carried out throughout the source code.
1134
1135All C code was converted to ANSI C; we got rid of all uses of the
1136Py_PROTO() macro, which makes the header files a lot more readable.
1137
1138Most of the portability hacks were moved to a new header file,
1139pyport.h; several other new header files were added and some old
1140header files were removed, in an attempt to create a more rational set
1141of header files. (Few of these ever need to be included explicitly;
1142they are all included by Python.h.)
1143
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001144Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001145and Win64, especially for the new Intel Itanium processor. Mick also
1146added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001147
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001148The C APIs to return an object's size have been update to consistently
1149use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1150previous versions, the abstract interfaces used PyXXX_Length and the
1151concrete interfaces used PyXXX_Size. The old names,
1152e.g. PyObject_Length, are still available for backwards compatibility
1153at the API level, but are deprecated.
1154
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001155The PyOS_CheckStack function has been implemented on Windows by
1156Fredrik Lundh. It prevents Python from failing with a stack overflow
1157on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001158
1159The GC changes resulted in creation of two new slots on object,
1160tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001161the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001162
1163The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001164C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001165
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001166PyErr_Format has been updated to automatically calculate the size of
1167the buffer needed to hold the formatted result string. This change
1168prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001169
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001170New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001171
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001172PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1173that are the same as their non-Ex counterparts except they take an
1174extra flag argument that tells them to close the file when done.
1175
1176XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001177
Tim Peters8b092332000-09-05 20:15:25 +00001178
1179Windows Changes
1180---------------
1181
1182New popen2/popen3/peopen4 in os module (see Changed Modules above).
1183
1184os.popen is much more usable on Windows 95 and 98. See Microsoft
1185Knowledge Base article Q150956. The Win9x workaround described there
1186is implemented by the new w9xpopen.exe helper in the root of your
1187Python installation. Note that Python uses this internally; it is not
1188a standalone program.
1189
1190Administrator privileges are no longer required to install Python
1191on Windows NT or Windows 2000. If you have administrator privileges,
1192Python's registry info will be written under HKEY_LOCAL_MACHINE.
1193Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001194under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001195uses of Python, but will prevent some advanced uses from working
1196(for example, running a Python script as an NT service, or possibly
1197from CGI).
1198
1199[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1200installer; instead, it installs the needed Tcl/Tk files directly in the
1201Python directory. If you already have a Tcl/Tk installation, this
1202wastes some disk space (about 4 Megs) but avoids problems with
1203conflicting Tcl/Tk installations, and makes it much easier for Python
1204to ensure that Tcl/Tk can find all its files.
1205
1206[This was new in 1.6] The Windows installer now installs by default in
1207\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1208
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001209
1210Updates to the changes between 1.5.2 and 1.6
1211--------------------------------------------
1212
1213The 1.6 NEWS file can't be changed after the release is done, so here
1214is some late-breaking news:
1215
1216New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1217and changes to getlocale() and setlocale().
1218
1219The new module is now enabled per default.
1220
1221It is not true that the encodings codecs cannot be used for normal
1222strings: the string.encode() (which is also present on 8-bit strings
1223!) allows using them for 8-bit strings too, e.g. to convert files from
1224cp1252 (Windows) to latin-1 or vice-versa.
1225
1226Japanese codecs are available from Tamito KAJIYAMA:
1227http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1228
1229
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001230======================================================================