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Tim Petersa3a3a032000-11-30 05:22:44 +00001What's New in Python 2.1 alpha 1?
2=================================
3
4Core language, builtins, and interpreter
5
Guido van Rossumf98eda02001-01-17 15:54:45 +00006- The comparison operators support "rich comparison overloading" (PEP
7 207). C extension types can provide a rich comparison function in
8 the new tp_richcompare slot in the type object. The cmp() function
9 and the C function PyObject_Compare() first try the new rich
10 comparison operators before trying the old 3-way comparison. There
11 is also a new C API PyObject_RichCompare() (which also falls back on
12 the old 3-way comparison, but does not constrain the outcome of the
13 rich comparison to a Boolean result).
14
15 The rich comparison function takes two objects (at least one of
16 which is guaranteed to have the type that provided the function) and
17 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
18 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
19 object, which may be NotImplemented (in which case the tp_compare
20 slot function is used as a fallback, if defined).
21
22 Classes can overload individual comparison operators by defining one
23 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
24 __ge__. There are no explicit "reversed argument" versions of
25 these; instead, __lt__ and __gt__ are each other's reverse, likewise
26 for__le__ and __ge__; __eq__ and __ne__ are their own reverse
27 (similar at the C level). No other implications are made; in
28 particular, Python does not assume that == is the inverse of !=, or
29 that < is the inverse of >=. This makes it possible to define types
30 with partial orderings.
31
32 Classes or types that want to implement (in)equality tests but not
33 the ordering operators (i.e. unordered types) should implement ==
34 and !=, and raise an error for the ordering operators.
35
36 It is possible to define types whose comparison results are not
37 Boolean; e.g. a matrix type might want to return a matrix of bits
38 for A < B, giving elementwise comparisons. Such types should ensure
39 that any interpretation of their value in a Boolean context raises
40 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
41 at the C level) to always raise an exception.
42
Barry Warsaw573b5412001-01-15 20:43:18 +000043- Functions and methods now support getting and setting arbitrarily
44 named attributes (PEP 232). Functions have a new __dict__
45 (a.k.a. func_dict) which hold the function attributes. Methods get
46 and set attributes on their underlying im_func. It is a TypeError
47 to set an attribute on a bound method.
48
Guido van Rossum051e3352001-01-15 19:11:10 +000049- The xrange() object implementation has been improved so that
50 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
51 limitation that in this case len(xrange(sys.maxint)) can't be
52 calculated, but the common idiom "for i in xrange(sys.maxint)" will
53 work fine as long as the index i doesn't actually reach 2**31.
54 (Python uses regular ints for sequence and string indices; fixing
55 that is much more work.)
56
Guido van Rossum1cc8f832001-01-12 16:25:08 +000057- Two changes to from...import:
58
59 1) "from M import X" now works even if M is not a real module; it's
60 basically a getattr() operation with AttributeError exceptions
61 changed into ImportError.
62
63 2) "from M import *" now looks for M.__all__ to decide which names to
64 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
65 filters out names starting with '_' as before. Whether or not
66 __all__ exists, there's no restriction on the type of M.
67
Guido van Rossumf61f1662001-01-10 20:13:55 +000068- File objects have a new method, xreadlines(). This is the fastest
69 way to iterate over all lines in a file:
70
71 for line in file.xreadlines():
72 ...do something to line...
73
74 See the xreadlines module (mentioned below) for how to do this for
75 other file-like objects.
76
77- Even if you don't use file.xreadlines(), you may expect a speedup on
78 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +000079 quite a bit in platform-specific ways: on systems (like Linux) that
80 support flockfile(), getc_unlocked(), and funlockfile(), those are
81 used by default. On systems (like Windows) without getc_unlocked(),
82 a complicated (but still thread-safe) method using fgets() is used by
83 default.
84
85 You can force use of the fgets() method by #define'ing
86 USE_FGETS_IN_GETLINE at build time (it may be faster than
87 getc_unlocked()).
88
89 You can force fgets() not to be used by #define'ing
90 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
91 test_bufio.py fails -- and let us know if it does!).
92
93- In addition, the fileinput module, while still slower than the other
94 methods on most platforms, has been sped up too, by using
95 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +000096
97- Support for run-time warnings has been added, including a new
98 command line option (-W) to specify the disposition of warnings.
99 See the description of the warnings module below.
100
101- Extensive changes have been made to the coercion code. This mostly
102 affects extension modules (which can now implement mixed-type
103 numerical operators without having to use coercion), but
104 occasionally, in boundary cases the coercion semantics have changed
105 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000106 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000107 supported -- instead of calling __rcmp__, __cmp__ is called with
108 reversed arguments.
109
Guido van Rossumf98eda02001-01-17 15:54:45 +0000110- In connection with the coercion changes, a new built-in singleton
111 object, NotImplemented is defined. This can be returned for
112 operations that wish to indicate they are not implemented for a
113 particular combination of arguments. From C, this is
114 Py_NotImplemented.
115
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000116- The interpreter accepts now bytecode files on the command line even
117 if they do not have a .pyc or .pyo extension. On Linux, after executing
118
119 echo ':pyc:M::\x87\xc6\x0d\x0a::/usr/local/bin/python:' > /proc/sys/fs/binfmt_misc/register
120
121 any byte code file can be used as an executable (i.e. as an argument
122 to execve(2)).
123
Tim Peters9940b802000-12-01 07:59:35 +0000124- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000125 character. In 1.6 and earlier, they never produced a sign,
126 and raised an error if the value of the long was too large
127 to fit in a Python int. In 2.0, they produced a sign if and
128 only if too large to fit in an int. This was inconsistent
129 across platforms (because the size of an int varies across
130 platforms), and inconsistent with hex() and oct(). Example:
131
132 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000133 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000134 'ffffffbe' # in 2.0 and before, on 32-bit machines
135 >>> hex(-0x42L)
136 '-0x42L' # in all versions of Python
137
Tim Peters9940b802000-12-01 07:59:35 +0000138 The behavior of %d formats for negative Python longs remains
139 the same as in 2.0 (although in 1.6 and before, they raised
140 an error if the long didn't fit in a Python int).
141
142 %u formats don't make sense for Python longs, but are allowed
143 and treated the same as %d in 2.1. In 2.0, a negative long
144 formatted via %u produced a sign if and only if too large to
145 fit in an int. In 1.6 and earlier, a negative long formatted
146 via %u raised an error if it was too big to fit in an int.
147
Guido van Rossum3661d392000-12-12 22:10:31 +0000148- Dictionary objects have an odd new method, popitem(). This removes
149 an arbitrary item from the dictionary and returns it (in the form of
150 a (key, value) pair). This can be useful for algorithms that use a
151 dictionary as a bag of "to do" items and repeatedly need to pick one
152 item. Such algorithms normally end up running in quadratic time;
153 using popitem() they can usually be made to run in linear time.
154
Tim Peters36cdad12000-12-29 02:06:45 +0000155Standard library
156
Guido van Rossumda91f222001-01-15 16:36:08 +0000157- The ftplib module now defaults to passive mode, which is deemed a
158 more useful default given that clients are often inside firewalls
159 these days. Note that this could break if ftplib is used to connect
160 to a *server* that is inside a firewall, from outside; this is
161 expected to be a very rare situation. To fix that, you can call
162 ftp.set_pasv(0).
163
Martin v. Löwis10a27872001-01-13 09:54:41 +0000164- The module site now treats .pth files not only for path configuration,
165 but also supports extensions to the initialization code: Lines starting
166 with import are executed.
167
Guido van Rossumf61f1662001-01-10 20:13:55 +0000168- There's a new module, warnings, which implements a mechanism for
169 issuing and filtering warnings. There are some new built-in
170 exceptions that serve as warning categories, and a new command line
171 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
172 turns warnings into errors). warnings.warn(message[, category])
173 issues a warning message; this can also be called from C as
174 PyErr_Warn(category, message).
175
176- A new module xreadlines was added. This exports a single factory
177 function, xreadlines(). The intention is that this code is the
178 absolutely fastest way to iterate over all lines in an open
179 file(-like) object:
180
181 import xreadlines
182 for line in xreadlines.xreadlines(file):
183 ...do something to line...
184
185 This is equivalent to the previous the speed record holder using
186 file.readlines(sizehint). Note that if file is a real file object
187 (as opposed to a file-like object), this is equivalent:
188
189 for line in file.xreadlines():
190 ...do something to line...
191
Tim Peters36cdad12000-12-29 02:06:45 +0000192- The bisect module has new functions bisect_left, insort_left,
193 bisect_right and insort_right. The old names bisect and insort
194 are now aliases for bisect_right and insort_right. XXX_right
195 and XXX_left methods differ in what happens when the new element
196 compares equal to one or more elements already in the list: the
197 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000198 right. Code that doesn't care where equal elements end up should
199 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000200
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000201- The new curses.panel module wraps the panel library that forms part
202 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
203
Guido van Rossumf61f1662001-01-10 20:13:55 +0000204- The SocketServer module now sets the allow_reuse_address flag by
205 default in the TCPServer class.
206
207- A new function, sys._getframe(), returns the stack frame pointer of
208 the caller. This is intended only as a building block for
209 higher-level mechanisms such as string interpolation.
210
211Build issues
212
213- On Linux (and possibly other Unix platforms), the readline and
214 _curses modules are automatically configured through
215 Modules/Setup.config. These, and the bsddb module (which was
216 already dynamically configured) are now built as shared libraries by
217 default.
218
219- Python now always uses its own (renamed) implementation of getopt()
220 -- there's too much variation among C library getopt()
221 implementations.
222
223- C++ compilers are better supported; the CXX macro is always set to a
224 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000225
Tim Petersd92dfe02000-12-12 01:18:41 +0000226Windows changes
227
228- select module: By default under Windows, a select() call
229 can specify no more than 64 sockets. Python now boosts
230 this Microsoft default to 512. If you need even more than
231 that, see the MS docs (you'll need to #define FD_SETSIZE
232 and recompile Python from source).
233
Guido van Rossumf61f1662001-01-10 20:13:55 +0000234- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
235 subdirectory is no more!
236
Tim Petersa3a3a032000-11-30 05:22:44 +0000237
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000238What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000239=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000240
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000241Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000242changes are in the file HISTORY. If you are making the jump directly
243from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
244HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000245
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000246Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
247the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
248http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000249
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000250--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000251
252======================================================================
253
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000254What's new in 2.0 (since release candidate 1)?
255==============================================
256
257Standard library
258
259- The copy_reg module was modified to clarify its intended use: to
260 register pickle support for extension types, not for classes.
261 pickle() will raise a TypeError if it is passed a class.
262
263- Fixed a bug in gettext's "normalize and expand" code that prevented
264 it from finding an existing .mo file.
265
266- Restored support for HTTP/0.9 servers in httplib.
267
Tim Peters989b7b92000-10-16 20:24:53 +0000268- The math module was changed to stop raising OverflowError in case of
269 underflow, and return 0 instead in underflow cases. Whether Python
270 used to raise OverflowError in case of underflow was platform-
271 dependent (it did when the platform math library set errno to ERANGE
272 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000273
274- Fixed a bug in StringIO that occurred when the file position was not
275 at the end of the file and write() was called with enough data to
276 extend past the end of the file.
277
278- Fixed a bug that caused Tkinter error messages to get lost on
279 Windows. The bug was fixed by replacing direct use of
280 interp->result with Tcl_GetStringResult(interp).
281
282- Fixed bug in urllib2 that caused it to fail when it received an HTTP
283 redirect response.
284
285- Several changes were made to distutils: Some debugging code was
286 removed from util. Fixed the installer used when an external zip
287 program (like WinZip) is not found; the source code for this
288 installer is in Misc/distutils. check_lib() was modified to behave
289 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
290 test for whether installed modules are on sys.path was changed to
291 use both normcase() and normpath().
292
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000293- Several minor bugs were fixed in the xml package (the minidom,
294 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000295
296- The regression test driver (regrtest.py) behavior when invoked with
297 -l changed: It now reports a count of objects that are recognized as
298 garbage but not freed by the garbage collector.
299
Tim Peters989b7b92000-10-16 20:24:53 +0000300- The regression test for the math module was changed to test
301 exceptional behavior when the test is run in verbose mode. Python
302 cannot yet guarantee consistent exception behavior across platforms,
303 so the exception part of test_math is run only in verbose mode, and
304 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000305
306Internals
307
308- PyOS_CheckStack() has been disabled on Win64, where it caused
309 test_sre to fail.
310
311Build issues
312
313- Changed compiler flags, so that gcc is always invoked with -Wall and
314 -Wstrict-prototypes. Users compiling Python with GCC should see
315 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000316 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000317 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000318
Tim Petersa3a3a032000-11-30 05:22:44 +0000319- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000320
321Tools and other miscellany
322
323- The compiler in Tools/compiler was updated to support the new
324 language features introduced in 2.0: extended print statement, list
325 comprehensions, and augmented assignments. The new compiler should
326 also be backwards compatible with Python 1.5.2; the compiler will
327 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000328 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000329
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000330What's new in 2.0 release candidate 1 (since beta 2)?
331=====================================================
332
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000333What is release candidate 1?
334
335We believe that release candidate 1 will fix all known bugs that we
336intend to fix for the 2.0 final release. This release should be a bit
337more stable than the previous betas. We would like to see even more
338widespread testing before the final release, so we are producing this
339release candidate. The final release will be exactly the same unless
340any show-stopping (or brown bag) bugs are found by testers of the
341release candidate.
342
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000343All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000344to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000345
346Core language, builtins, and interpreter
347
348- A bug that caused crashes when __coerce__ was used with augmented
349 assignment, e.g. +=, was fixed.
350
351- Raise ZeroDivisionError when raising zero to a negative number,
352 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
353 power operator and the result of math.pow(0.0, -2.0) will vary by
354 platform. On Linux, it raises a ValueError.
355
356- A bug in Unicode string interpolation was fixed that occasionally
357 caused errors with formats including "%%". For example, the
358 following expression "%% %s" % u"abc" no longer raises a TypeError.
359
360- Compilation of deeply nested expressions raises MemoryError instead
361 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
362
363- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
364 rendering them useless. They are now written in binary mode again.
365
366Standard library
367
368- Keyword arguments are now accepted for most pattern and match object
369 methods in SRE, the standard regular expression engine.
370
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000371- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000372 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000373
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000374- Several bugs in the Unicode handling and error handling in _tkinter
375 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000376
377- Fix memory management errors in Merge() and Tkapp_Call() routines.
378
379- Several changes were made to cStringIO to make it compatible with
380 the file-like object interface and with StringIO. If operations are
381 performed on a closed object, an exception is raised. The truncate
382 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000383 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000384
385- There were many changes made to the linuxaudiodev module and its
386 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000387 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000388
389 Note that this module is named poorly, because it should work
390 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000391 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000392
393 The module now raises exceptions when errors occur instead of
394 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
395 audio) and defines a getptr() method that calls the
396 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
397
398- The library_version attribute, introduced in an earlier beta, was
399 removed because it can not be supported with early versions of the C
400 readline library, which provides no way to determine the version at
401 compile-time.
402
403- The binascii module is now enabled on Win64.
404
Tim Peters46446d62000-10-09 21:19:31 +0000405- tokenize.py no longer suffers "recursion depth" errors when parsing
406 programs with very long string literals.
407
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000408Internals
409
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000410- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000411 which is called when the interpreter starts up to determine where
412 the standard library is installed. These vulnerabilities affect all
413 previous versions of Python and can be exploited by setting very
414 long values for PYTHONHOME or argv[0]. The risk is greatest for a
415 setuid Python script, although use of the wrapper in
416 Misc/setuid-prog.c will eliminate the vulnerability.
417
418- Fixed garbage collection bugs in instance creation that were
419 triggered when errors occurred during initialization. The solution,
420 applied in cPickle and in PyInstance_New(), is to call
421 PyObject_GC_Init() after the initialization of the object's
422 container attributes is complete.
423
424- pyexpat adds definitions of PyModule_AddStringConstant and
425 PyModule_AddObject if the Python version is less than 2.0, which
426 provides compatibility with PyXML on Python 1.5.2.
427
428- If the platform has a bogus definition for LONG_BIT (the number of
429 bits in a long), an error will be reported at compile time.
430
431- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
432 collection crashes and possibly other, unreported crashes.
433
434- Fixed a memory leak in _PyUnicode_Fini().
435
436Build issues
437
438- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000439 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000440 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000441
442- The mmap.PAGESIZE constant is now initialized using sysconf when
443 possible, which eliminates a dependency on -lucb for Reliant UNIX.
444
445- The md5 file should now compile on all platforms.
446
447- The select module now compiles on platforms that do not define
448 POLLRDNORM and related constants.
449
450- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000451 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000452
Jeremy Hylton10921202000-10-09 18:34:12 +0000453- BeOS: A number of changes were made to the build and installation
454 process. ar-fake now operates on a directory of object files.
455 dl_export.h is gone, and its macros now appear on the mwcc command
456 line during build on PPC BeOS.
457
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000458- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000459 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000460
461- Cygwin: Support for shared libraries, Tkinter, and sockets.
462
463- SunOS 4.1.4_JL: Fix test for directory existence in configure.
464
465Tools and other miscellany
466
467- Removed debugging prints from main used with freeze.
468
Tim Peters46446d62000-10-09 21:19:31 +0000469- IDLE auto-indent no longer crashes when it encounters Unicode
470 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000471
472What's new in 2.0 beta 2 (since beta 1)?
473========================================
474
475Core language, builtins, and interpreter
476
Tim Peters482c0212000-09-26 06:33:09 +0000477- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000478 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000479
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000480- Add -h and -V command line options to print the usage message and
481 Python version number and exit immediately.
482
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000483- eval() and exec accept Unicode objects as code parameters.
484
485- getattr() and setattr() now also accept Unicode objects for the
486 attribute name, which are converted to strings using the default
487 encoding before lookup.
488
489- Multiplication on string and Unicode now does proper bounds
490 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
491 string is too long."
492
493- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000494 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000495
Jeremy Hylton1b618592000-09-26 05:32:36 +0000496
497Standard library and extensions
498
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000499- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000500 argument checking; it still takes no arguments.
501
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000502- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000503
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000504- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000505
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000506- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000507
508- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000509 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000510
511- copy: Copy Unicode objects atomically.
512
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000513- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000514
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000515- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000516
Fred Drake67233bc2000-09-26 16:40:27 +0000517- dbm: Add get() and setdefault() methods to dbm object. Add constant
518 `library' to module that names the library used. Added doc strings
519 and method names to error messages. Uses configure to determine
520 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
521 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000522
523- distutils: Update to version 0.9.3.
524
525- dl: Add several dl.RTLD_ constants.
526
527- fpectl: Now supported on FreeBSD.
528
529- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
530 found by the collector will be saved in gc.garbage. This is useful
531 for debugging a program that creates reference cycles.
532
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000533- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000534 of HTTP class. Do not close socket on zero-length response. Do not
535 crash when server sends invalid content-length header.
536
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000537- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000538
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000539- marshal: When reading a short, sign-extend on platforms where shorts
540 are bigger than 16 bits. When reading a long, repair the unportable
541 sign extension that was being done for 64-bit machines. (It assumed
542 that signed right shift sign-extends.)
543
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000544- operator: Add contains(), invert(), __invert__() as aliases for
545 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000546
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000547- os: Add support for popen2() and popen3() on all platforms where
548 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000549
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000550- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000551 clicking on a file in Explorer (or passing the file name to the
552 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000553
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000554- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000555 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000556
557- pickle: Now raises ValueError when an invalid pickle that contains
558 a non-string repr where a string repr was expected. This behavior
559 matches cPickle.
560
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000561- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000562
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000563- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000564
565- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000566 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000567 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000568
569- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000570 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000571
572- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000573 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000574 few cycles during startup since the first call to
575 setdefaultencoding() will initialize the codec registry and the
576 encodings package.
577
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000578- socket: Support for size hint in readlines() method of object returned
579 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000580
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000581- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000582 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000583 is followed by whitespace.
584
Tim Petersa3a3a032000-11-30 05:22:44 +0000585- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000586
587- struct: Check ranges for bytes and shorts.
588
589- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000590 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000591
592- Tkinter: Image objects are now guaranteed to have unique ids. Set
593 event.delta to zero if Tk version doesn't support mousewheel.
594 Removed some debugging prints.
595
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000596- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000597
Fred Drake67233bc2000-09-26 16:40:27 +0000598- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000599 which works around a bug in Norton AntiVirus 2000 that leads directly
600 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000601
602- xml: New version detection code allows PyXML to override standard
603 XML package if PyXML version is greater than 0.6.1.
604
Fred Drake64bb3802000-09-26 16:21:35 +0000605- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
606 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
607 tree only for nodes which are sufficiently interesting to a specific
608 application. Does not provide the HTML-specific extensions. Still
609 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000610
Fred Drake64bb3802000-09-26 16:21:35 +0000611- xml.sax: SAX 2 support for Python, including all the handler
612 interfaces needed to process XML 1.0 compliant XML. Some
613 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000614
Fred Drake64bb3802000-09-26 16:21:35 +0000615- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
616 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000617
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000618
Jeremy Hylton1b618592000-09-26 05:32:36 +0000619C API
620
621- Add three new convenience functions for module initialization --
622 PyModule_AddObject(), PyModule_AddIntConstant(), and
623 PyModule_AddStringConstant().
624
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000625- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000626 removed and add #error to Python.h if NULL isn't defined after
627 #include of stdio.h.
628
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000629- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000630 backwards compatibility (at the source level) with old extensions.
631
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000632- A wrapper API was added for signal() and sigaction(). Instead of
633 either function, always use PyOS_getsig() to get a signal handler
634 and PyOS_setsig() to set one. A new convenience typedef
635 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000636
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000637- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000638 internal data buffer and size of a string object -- or the default
639 encoded version of a Unicode object.
640
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000641- PyString_Size() and PyString_AsString() accept Unicode objects.
642
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000643- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000644 exists). INT_MAX and LONG_MAX will always be defined, even if
645 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000646
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000647- PyFloat_FromString takes a second argument, pend, that was
648 effectively useless. It is now officially useless but preserved for
649 backwards compatibility. If the pend argument is not NULL, *pend is
650 set to NULL.
651
652- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
653 for the attribute name. See note on getattr() above.
654
655- A few bug fixes to argument processing for Unicode.
656 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
657 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
658 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000659 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000660
661- Py_BuildValue accepts B format (for bgen-generated code).
662
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000663
Jeremy Hylton1b618592000-09-26 05:32:36 +0000664Internals
665
666- On Unix, fix code for finding Python installation directory so that
667 it works when argv[0] is a relative path.
668
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000669- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000670 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000671 rather than by generating a copy of the object.
672
Tim Peters482c0212000-09-26 06:33:09 +0000673- Several of the internal Unicode tables are much smaller now, and
674 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000675
Jeremy Hylton97693b02000-09-26 17:42:51 +0000676- In the garbage collector: Fixed bug in collection of tuples. Fixed
677 bug that caused some instances to be removed from the container set
678 while they were still live. Fixed parsing in gc.set_debug() for
679 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000680
681- Fixed refcount problem in instance deallocation that only occurred
682 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
683
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000684- On Windows, getpythonregpath is now protected against null data in
685 registry key.
686
687- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000688 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000689
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000690
Jeremy Hylton1b618592000-09-26 05:32:36 +0000691Build and platform-specific issues
692
693- Better support of GNU Pth via --with-pth configure option.
694
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000695- Python/C API now properly exposed to dynamically-loaded extension
696 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000697
698- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
699 Don't define MS_SYNC to be zero when it is undefined. Added missing
700 prototypes in posixmodule.c.
701
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000702- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000703 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000704
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000705- Fix largefile support on older NetBSD systems and OpenBSD by adding
706 define for TELL64.
707
708
709Tools and other miscellany
710
711- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
712
713- freeze: The modulefinder now works with 2.0 opcodes.
714
Tim Petersa3a3a032000-11-30 05:22:44 +0000715- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000716 Move hackery of sys.argv until after the Tk instance has been
717 created, which allows the application-specific Tkinter
718 initialization to be executed if present; also pass an explicit
719 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000720
Jeremy Hylton1b618592000-09-26 05:32:36 +0000721
722What's new in 2.0 beta 1?
723=========================
724
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000725Source Incompatibilities
726------------------------
727
728None. Note that 1.6 introduced several incompatibilities with 1.5.2,
729such as single-argument append(), connect() and bind(), and changes to
730str(long) and repr(float).
731
732
733Binary Incompatibilities
734------------------------
735
736- Third party extensions built for Python 1.5.x or 1.6 cannot be used
737with Python 2.0; these extensions will have to be rebuilt for Python
7382.0.
739
740- On Windows, attempting to import a third party extension built for
741Python 1.5.x or 1.6 results in an immediate crash; there's not much we
742can do about this. Check your PYTHONPATH environment variable!
743
744- Python bytecode files (*.pyc and *.pyo) are not compatible between
745releases.
746
747
748Overview of Changes Since 1.6
749-----------------------------
750
751There are many new modules (including brand new XML support through
752the xml package, and i18n support through the gettext module); a list
753of all new modules is included below. Lots of bugs have been fixed.
754
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000755The process for making major new changes to the language has changed
756since Python 1.6. Enhancements must now be documented by a Python
757Enhancement Proposal (PEP) before they can be accepted.
758
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000759There are several important syntax enhancements, described in more
760detail below:
761
762 - Augmented assignment, e.g. x += 1
763
764 - List comprehensions, e.g. [x**2 for x in range(10)]
765
766 - Extended import statement, e.g. import Module as Name
767
768 - Extended print statement, e.g. print >> file, "Hello"
769
770Other important changes:
771
772 - Optional collection of cyclical garbage
773
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000774Python Enhancement Proposal (PEP)
775---------------------------------
776
777PEP stands for Python Enhancement Proposal. A PEP is a design
778document providing information to the Python community, or describing
779a new feature for Python. The PEP should provide a concise technical
780specification of the feature and a rationale for the feature.
781
782We intend PEPs to be the primary mechanisms for proposing new
783features, for collecting community input on an issue, and for
784documenting the design decisions that have gone into Python. The PEP
785author is responsible for building consensus within the community and
786documenting dissenting opinions.
787
788The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000789
790Augmented Assignment
791--------------------
792
793This must have been the most-requested feature of the past years!
794Eleven new assignment operators were added:
795
Guido van Rossume905e952000-09-05 12:42:46 +0000796 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000797
798For example,
799
800 A += B
801
802is similar to
803
804 A = A + B
805
806except that A is evaluated only once (relevant when A is something
807like dict[index].attr).
808
809However, if A is a mutable object, A may be modified in place. Thus,
810if A is a number or a string, A += B has the same effect as A = A+B
811(except A is only evaluated once); but if a is a list, A += B has the
812same effect as A.extend(B)!
813
814Classes and built-in object types can override the new operators in
815order to implement the in-place behavior; the not-in-place behavior is
816used automatically as a fallback when an object doesn't implement the
817in-place behavior. For classes, the method name is derived from the
818method name for the corresponding not-in-place operator by inserting
819an 'i' in front of the name, e.g. __iadd__ implements in-place
820__add__.
821
822Augmented assignment was implemented by Thomas Wouters.
823
824
825List Comprehensions
826-------------------
827
828This is a flexible new notation for lists whose elements are computed
829from another list (or lists). The simplest form is:
830
831 [<expression> for <variable> in <sequence>]
832
Guido van Rossum56db0952000-09-06 23:34:25 +0000833For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000834This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000835
836You can also add a condition:
837
838 [<expression> for <variable> in <sequence> if <condition>]
839
840For example, [w for w in words if w == w.lower()] would yield the list
841of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000842than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000843
844You can also have nested for loops and more than one 'if' clause. For
845example, here's a function that flattens a sequence of sequences::
846
847 def flatten(seq):
848 return [x for subseq in seq for x in subseq]
849
850 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
851
852This prints
853
854 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
855
856List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000857Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000858
859
860Extended Import Statement
861-------------------------
862
863Many people have asked for a way to import a module under a different
864name. This can be accomplished like this:
865
866 import foo
867 bar = foo
868 del foo
869
870but this common idiom gets old quickly. A simple extension of the
871import statement now allows this to be written as follows:
872
873 import foo as bar
874
875There's also a variant for 'from ... import':
876
877 from foo import bar as spam
878
879This also works with packages; e.g. you can write this:
880
881 import test.regrtest as regrtest
882
883Note that 'as' is not a new keyword -- it is recognized only in this
884context (this is only possible because the syntax for the import
885statement doesn't involve expressions).
886
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000887Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000888
889
890Extended Print Statement
891------------------------
892
893Easily the most controversial new feature, this extension to the print
894statement adds an option to make the output go to a different file
895than the default sys.stdout.
896
897For example, to write an error message to sys.stderr, you can now
898write:
899
900 print >> sys.stderr, "Error: bad dog!"
901
902As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +0000903evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000904
905 print >> None, "Hello world"
906
907is equivalent to
908
909 print "Hello world"
910
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000911Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000912
913
914Optional Collection of Cyclical Garbage
915---------------------------------------
916
917Python is now equipped with a garbage collector that can hunt down
918cyclical references between Python objects. It's no replacement for
919reference counting; in fact, it depends on the reference counts being
920correct, and decides that a set of objects belong to a cycle if all
921their reference counts can be accounted for from their references to
922each other. This devious scheme was first proposed by Eric Tiedemann,
923and brought to implementation by Neil Schemenauer.
924
925There's a module "gc" that lets you control some parameters of the
926garbage collection. There's also an option to the configure script
927that lets you enable or disable the garbage collection. In 2.0b1,
928it's on by default, so that we (hopefully) can collect decent user
929experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +0000930performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000931off by default in the final 2.0 release.
932
933
934Smaller Changes
935---------------
936
937A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
938map(None, seq1, seq2, ...) when the sequences have the same length;
939i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
940the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000941zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000942
943sys.version_info is a tuple (major, minor, micro, level, serial).
944
945Dictionaries have an odd new method, setdefault(key, default).
946dict.setdefault(key, default) returns dict[key] if it exists; if not,
947it sets dict[key] to default and returns that value. Thus:
948
949 dict.setdefault(key, []).append(item)
950
951does the same work as this common idiom:
952
953 if not dict.has_key(key):
954 dict[key] = []
955 dict[key].append(item)
956
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000957There are two new variants of SyntaxError that are raised for
958indentation-related errors: IndentationError and TabError.
959
960Changed \x to consume exactly two hex digits; see PEP 223. Added \U
961escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +0000962
963The limits on the size of expressions and file in Python source code
964have been raised from 2**16 to 2**32. Previous versions of Python
965were limited because the maximum argument size the Python VM accepted
966was 2**16. This limited the size of object constructor expressions,
967e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
968limit was raised thanks to a patch by Charles Waldman that effectively
969fixes the problem. It is now much more likely that you will be
970limited by available memory than by an arbitrary limit in Python.
971
972The interpreter's maximum recursion depth can be modified by Python
973programs using sys.getrecursionlimit and sys.setrecursionlimit. This
974limit is the maximum number of recursive calls that can be made by
975Python code. The limit exists to prevent infinite recursion from
976overflowing the C stack and causing a core dump. The default value is
9771000. The maximum safe value for a particular platform can be found
978by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000979
980New Modules and Packages
981------------------------
982
983atexit - for registering functions to be called when Python exits.
984
985imputil - Greg Stein's alternative API for writing custom import
986hooks.
987
988pyexpat - an interface to the Expat XML parser, contributed by Paul
989Prescod.
990
991xml - a new package with XML support code organized (so far) in three
992subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
993would fill a volume. There's a special feature whereby a
994user-installed package named _xmlplus overrides the standard
995xmlpackage; this is intended to give the XML SIG a hook to distribute
996backwards-compatible updates to the standard xml package.
997
998webbrowser - a platform-independent API to launch a web browser.
999
1000
Guido van Rossume905e952000-09-05 12:42:46 +00001001Changed Modules
1002---------------
1003
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001004array -- new methods for array objects: count, extend, index, pop, and
1005remove
1006
1007binascii -- new functions b2a_hex and a2b_hex that convert between
1008binary data and its hex representation
1009
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001010calendar -- Many new functions that support features including control
1011over which day of the week is the first day, returning strings instead
1012of printing them. Also new symbolic constants for days of week,
1013e.g. MONDAY, ..., SUNDAY.
1014
1015cgi -- FieldStorage objects have a getvalue method that works like a
1016dictionary's get method and returns the value attribute of the object.
1017
1018ConfigParser -- The parser object has new methods has_option,
1019remove_section, remove_option, set, and write. They allow the module
1020to be used for writing config files as well as reading them.
1021
1022ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001023optionally support the RFC 959 REST command.
1024
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001025gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001026
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001027httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1028the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001029
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001030locale -- implement getdefaultlocale for Win32 and Macintosh
1031
1032marshal -- no longer dumps core when marshaling deeply nested or
1033recursive data structures
1034
1035os -- new functions isatty, seteuid, setegid, setreuid, setregid
1036
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001037os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1038support under Unix.
1039
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001040os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001041
1042os.path -- fix semantics of os.path.commonprefix
1043
1044smtplib -- support for sending very long messages
1045
1046socket -- new function getfqdn()
1047
1048readline -- new functions to read, write and truncate history files.
1049The readline section of the library reference manual contains an
1050example.
1051
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001052select -- add interface to poll system call
1053
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001054shutil -- new copyfileobj function
1055
1056SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1057HTTP server.
1058
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001059Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001060
1061urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001062e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001063
1064whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001065
1066
1067Obsolete Modules
1068----------------
1069
1070None. However note that 1.6 made a whole slew of modules obsolete:
1071stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1072poly, zmod, strop, util, whatsound.
1073
1074
1075Changed, New, Obsolete Tools
1076----------------------------
1077
Tim Peters8b092332000-09-05 20:15:25 +00001078None.
Guido van Rossume905e952000-09-05 12:42:46 +00001079
1080
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001081C-level Changes
1082---------------
1083
1084Several cleanup jobs were carried out throughout the source code.
1085
1086All C code was converted to ANSI C; we got rid of all uses of the
1087Py_PROTO() macro, which makes the header files a lot more readable.
1088
1089Most of the portability hacks were moved to a new header file,
1090pyport.h; several other new header files were added and some old
1091header files were removed, in an attempt to create a more rational set
1092of header files. (Few of these ever need to be included explicitly;
1093they are all included by Python.h.)
1094
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001095Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001096and Win64, especially for the new Intel Itanium processor. Mick also
1097added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001098
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001099The C APIs to return an object's size have been update to consistently
1100use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1101previous versions, the abstract interfaces used PyXXX_Length and the
1102concrete interfaces used PyXXX_Size. The old names,
1103e.g. PyObject_Length, are still available for backwards compatibility
1104at the API level, but are deprecated.
1105
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001106The PyOS_CheckStack function has been implemented on Windows by
1107Fredrik Lundh. It prevents Python from failing with a stack overflow
1108on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001109
1110The GC changes resulted in creation of two new slots on object,
1111tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001112the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001113
1114The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001115C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001116
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001117PyErr_Format has been updated to automatically calculate the size of
1118the buffer needed to hold the formatted result string. This change
1119prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001120
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001121New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001122
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001123PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1124that are the same as their non-Ex counterparts except they take an
1125extra flag argument that tells them to close the file when done.
1126
1127XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001128
Tim Peters8b092332000-09-05 20:15:25 +00001129
1130Windows Changes
1131---------------
1132
1133New popen2/popen3/peopen4 in os module (see Changed Modules above).
1134
1135os.popen is much more usable on Windows 95 and 98. See Microsoft
1136Knowledge Base article Q150956. The Win9x workaround described there
1137is implemented by the new w9xpopen.exe helper in the root of your
1138Python installation. Note that Python uses this internally; it is not
1139a standalone program.
1140
1141Administrator privileges are no longer required to install Python
1142on Windows NT or Windows 2000. If you have administrator privileges,
1143Python's registry info will be written under HKEY_LOCAL_MACHINE.
1144Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001145under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001146uses of Python, but will prevent some advanced uses from working
1147(for example, running a Python script as an NT service, or possibly
1148from CGI).
1149
1150[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1151installer; instead, it installs the needed Tcl/Tk files directly in the
1152Python directory. If you already have a Tcl/Tk installation, this
1153wastes some disk space (about 4 Megs) but avoids problems with
1154conflicting Tcl/Tk installations, and makes it much easier for Python
1155to ensure that Tcl/Tk can find all its files.
1156
1157[This was new in 1.6] The Windows installer now installs by default in
1158\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1159
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001160
1161Updates to the changes between 1.5.2 and 1.6
1162--------------------------------------------
1163
1164The 1.6 NEWS file can't be changed after the release is done, so here
1165is some late-breaking news:
1166
1167New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1168and changes to getlocale() and setlocale().
1169
1170The new module is now enabled per default.
1171
1172It is not true that the encodings codecs cannot be used for normal
1173strings: the string.encode() (which is also present on 8-bit strings
1174!) allows using them for 8-bit strings too, e.g. to convert files from
1175cp1252 (Windows) to latin-1 or vice-versa.
1176
1177Japanese codecs are available from Tamito KAJIYAMA:
1178http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1179
1180
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001181======================================================================