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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
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +00006- There is a new Unicode companion to the builtin str() function
7 called unistr(). Like str(), it calls either the tp_str slot of
8 objects or the "__str__" method and converts the returned value
9 to an Unicode object (in case this is necessary).
10
11 The unistr() is complemented by a new PyObject_Unicode() C API
12 which behaves in the same way.
13
Guido van Rossumf98eda02001-01-17 15:54:45 +000014- The comparison operators support "rich comparison overloading" (PEP
15 207). C extension types can provide a rich comparison function in
16 the new tp_richcompare slot in the type object. The cmp() function
17 and the C function PyObject_Compare() first try the new rich
18 comparison operators before trying the old 3-way comparison. There
19 is also a new C API PyObject_RichCompare() (which also falls back on
20 the old 3-way comparison, but does not constrain the outcome of the
21 rich comparison to a Boolean result).
22
23 The rich comparison function takes two objects (at least one of
24 which is guaranteed to have the type that provided the function) and
25 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
26 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
27 object, which may be NotImplemented (in which case the tp_compare
28 slot function is used as a fallback, if defined).
29
30 Classes can overload individual comparison operators by defining one
31 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +000032 __ge__. There are no explicit "reflected argument" versions of
33 these; instead, __lt__ and __gt__ are each other's reflection,
34 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
35 reflection (similar at the C level). No other implications are
36 made; in particular, Python does not assume that == is the Boolean
37 inverse of !=, or that < is the Boolean inverse of >=. This makes
38 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +000039
40 Classes or types that want to implement (in)equality tests but not
41 the ordering operators (i.e. unordered types) should implement ==
42 and !=, and raise an error for the ordering operators.
43
Guido van Rossuma88479f2001-01-18 14:28:08 +000044 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +000045 Boolean; e.g. a matrix type might want to return a matrix of bits
46 for A < B, giving elementwise comparisons. Such types should ensure
47 that any interpretation of their value in a Boolean context raises
48 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
49 at the C level) to always raise an exception.
50
Guido van Rossuma88479f2001-01-18 14:28:08 +000051- Complex numbers use rich comparisons to define == and != but raise
52 an exception for <, <=, > and >=. Unfortunately, this also means
53 that cmp() of two complex numbers raises an exception when the two
54 numbers differ. Since it is not mathematically meaningful to compare
55 complex numbers except for equality, I hope that this doesn't break
56 too much code.
57
Barry Warsaw573b5412001-01-15 20:43:18 +000058- Functions and methods now support getting and setting arbitrarily
59 named attributes (PEP 232). Functions have a new __dict__
60 (a.k.a. func_dict) which hold the function attributes. Methods get
61 and set attributes on their underlying im_func. It is a TypeError
62 to set an attribute on a bound method.
63
Guido van Rossum051e3352001-01-15 19:11:10 +000064- The xrange() object implementation has been improved so that
65 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
66 limitation that in this case len(xrange(sys.maxint)) can't be
67 calculated, but the common idiom "for i in xrange(sys.maxint)" will
68 work fine as long as the index i doesn't actually reach 2**31.
69 (Python uses regular ints for sequence and string indices; fixing
70 that is much more work.)
71
Guido van Rossum1cc8f832001-01-12 16:25:08 +000072- Two changes to from...import:
73
74 1) "from M import X" now works even if M is not a real module; it's
75 basically a getattr() operation with AttributeError exceptions
76 changed into ImportError.
77
78 2) "from M import *" now looks for M.__all__ to decide which names to
79 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
80 filters out names starting with '_' as before. Whether or not
81 __all__ exists, there's no restriction on the type of M.
82
Guido van Rossumf61f1662001-01-10 20:13:55 +000083- File objects have a new method, xreadlines(). This is the fastest
84 way to iterate over all lines in a file:
85
86 for line in file.xreadlines():
87 ...do something to line...
88
89 See the xreadlines module (mentioned below) for how to do this for
90 other file-like objects.
91
92- Even if you don't use file.xreadlines(), you may expect a speedup on
93 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +000094 quite a bit in platform-specific ways: on systems (like Linux) that
95 support flockfile(), getc_unlocked(), and funlockfile(), those are
96 used by default. On systems (like Windows) without getc_unlocked(),
97 a complicated (but still thread-safe) method using fgets() is used by
98 default.
99
100 You can force use of the fgets() method by #define'ing
101 USE_FGETS_IN_GETLINE at build time (it may be faster than
102 getc_unlocked()).
103
104 You can force fgets() not to be used by #define'ing
105 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
106 test_bufio.py fails -- and let us know if it does!).
107
108- In addition, the fileinput module, while still slower than the other
109 methods on most platforms, has been sped up too, by using
110 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000111
112- Support for run-time warnings has been added, including a new
113 command line option (-W) to specify the disposition of warnings.
114 See the description of the warnings module below.
115
116- Extensive changes have been made to the coercion code. This mostly
117 affects extension modules (which can now implement mixed-type
118 numerical operators without having to use coercion), but
119 occasionally, in boundary cases the coercion semantics have changed
120 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000121 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000122 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000123 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000124
Guido van Rossumf98eda02001-01-17 15:54:45 +0000125- In connection with the coercion changes, a new built-in singleton
126 object, NotImplemented is defined. This can be returned for
127 operations that wish to indicate they are not implemented for a
128 particular combination of arguments. From C, this is
129 Py_NotImplemented.
130
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000131- The interpreter accepts now bytecode files on the command line even
132 if they do not have a .pyc or .pyo extension. On Linux, after executing
133
134 echo ':pyc:M::\x87\xc6\x0d\x0a::/usr/local/bin/python:' > /proc/sys/fs/binfmt_misc/register
135
136 any byte code file can be used as an executable (i.e. as an argument
137 to execve(2)).
138
Tim Peters9940b802000-12-01 07:59:35 +0000139- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000140 character. In 1.6 and earlier, they never produced a sign,
141 and raised an error if the value of the long was too large
142 to fit in a Python int. In 2.0, they produced a sign if and
143 only if too large to fit in an int. This was inconsistent
144 across platforms (because the size of an int varies across
145 platforms), and inconsistent with hex() and oct(). Example:
146
147 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000148 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000149 'ffffffbe' # in 2.0 and before, on 32-bit machines
150 >>> hex(-0x42L)
151 '-0x42L' # in all versions of Python
152
Tim Peters9940b802000-12-01 07:59:35 +0000153 The behavior of %d formats for negative Python longs remains
154 the same as in 2.0 (although in 1.6 and before, they raised
155 an error if the long didn't fit in a Python int).
156
157 %u formats don't make sense for Python longs, but are allowed
158 and treated the same as %d in 2.1. In 2.0, a negative long
159 formatted via %u produced a sign if and only if too large to
160 fit in an int. In 1.6 and earlier, a negative long formatted
161 via %u raised an error if it was too big to fit in an int.
162
Guido van Rossum3661d392000-12-12 22:10:31 +0000163- Dictionary objects have an odd new method, popitem(). This removes
164 an arbitrary item from the dictionary and returns it (in the form of
165 a (key, value) pair). This can be useful for algorithms that use a
166 dictionary as a bag of "to do" items and repeatedly need to pick one
167 item. Such algorithms normally end up running in quadratic time;
168 using popitem() they can usually be made to run in linear time.
169
Tim Peters36cdad12000-12-29 02:06:45 +0000170Standard library
171
Guido van Rossumda91f222001-01-15 16:36:08 +0000172- The ftplib module now defaults to passive mode, which is deemed a
173 more useful default given that clients are often inside firewalls
174 these days. Note that this could break if ftplib is used to connect
175 to a *server* that is inside a firewall, from outside; this is
176 expected to be a very rare situation. To fix that, you can call
177 ftp.set_pasv(0).
178
Martin v. Löwis10a27872001-01-13 09:54:41 +0000179- The module site now treats .pth files not only for path configuration,
180 but also supports extensions to the initialization code: Lines starting
181 with import are executed.
182
Guido van Rossumf61f1662001-01-10 20:13:55 +0000183- There's a new module, warnings, which implements a mechanism for
184 issuing and filtering warnings. There are some new built-in
185 exceptions that serve as warning categories, and a new command line
186 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
187 turns warnings into errors). warnings.warn(message[, category])
188 issues a warning message; this can also be called from C as
189 PyErr_Warn(category, message).
190
191- A new module xreadlines was added. This exports a single factory
192 function, xreadlines(). The intention is that this code is the
193 absolutely fastest way to iterate over all lines in an open
194 file(-like) object:
195
196 import xreadlines
197 for line in xreadlines.xreadlines(file):
198 ...do something to line...
199
200 This is equivalent to the previous the speed record holder using
201 file.readlines(sizehint). Note that if file is a real file object
202 (as opposed to a file-like object), this is equivalent:
203
204 for line in file.xreadlines():
205 ...do something to line...
206
Tim Peters36cdad12000-12-29 02:06:45 +0000207- The bisect module has new functions bisect_left, insort_left,
208 bisect_right and insort_right. The old names bisect and insort
209 are now aliases for bisect_right and insort_right. XXX_right
210 and XXX_left methods differ in what happens when the new element
211 compares equal to one or more elements already in the list: the
212 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000213 right. Code that doesn't care where equal elements end up should
214 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000215
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000216- The new curses.panel module wraps the panel library that forms part
217 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
218
Guido van Rossumf61f1662001-01-10 20:13:55 +0000219- The SocketServer module now sets the allow_reuse_address flag by
220 default in the TCPServer class.
221
222- A new function, sys._getframe(), returns the stack frame pointer of
223 the caller. This is intended only as a building block for
224 higher-level mechanisms such as string interpolation.
225
226Build issues
227
228- On Linux (and possibly other Unix platforms), the readline and
229 _curses modules are automatically configured through
230 Modules/Setup.config. These, and the bsddb module (which was
231 already dynamically configured) are now built as shared libraries by
232 default.
233
234- Python now always uses its own (renamed) implementation of getopt()
235 -- there's too much variation among C library getopt()
236 implementations.
237
238- C++ compilers are better supported; the CXX macro is always set to a
239 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000240
Tim Petersd92dfe02000-12-12 01:18:41 +0000241Windows changes
242
243- select module: By default under Windows, a select() call
244 can specify no more than 64 sockets. Python now boosts
245 this Microsoft default to 512. If you need even more than
246 that, see the MS docs (you'll need to #define FD_SETSIZE
247 and recompile Python from source).
248
Guido van Rossumf61f1662001-01-10 20:13:55 +0000249- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
250 subdirectory is no more!
251
Tim Petersa3a3a032000-11-30 05:22:44 +0000252
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000253What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000254=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000255
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000256Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000257changes are in the file HISTORY. If you are making the jump directly
258from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
259HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000260
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000261Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
262the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
263http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000264
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000265--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000266
267======================================================================
268
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000269What's new in 2.0 (since release candidate 1)?
270==============================================
271
272Standard library
273
274- The copy_reg module was modified to clarify its intended use: to
275 register pickle support for extension types, not for classes.
276 pickle() will raise a TypeError if it is passed a class.
277
278- Fixed a bug in gettext's "normalize and expand" code that prevented
279 it from finding an existing .mo file.
280
281- Restored support for HTTP/0.9 servers in httplib.
282
Tim Peters989b7b92000-10-16 20:24:53 +0000283- The math module was changed to stop raising OverflowError in case of
284 underflow, and return 0 instead in underflow cases. Whether Python
285 used to raise OverflowError in case of underflow was platform-
286 dependent (it did when the platform math library set errno to ERANGE
287 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000288
289- Fixed a bug in StringIO that occurred when the file position was not
290 at the end of the file and write() was called with enough data to
291 extend past the end of the file.
292
293- Fixed a bug that caused Tkinter error messages to get lost on
294 Windows. The bug was fixed by replacing direct use of
295 interp->result with Tcl_GetStringResult(interp).
296
297- Fixed bug in urllib2 that caused it to fail when it received an HTTP
298 redirect response.
299
300- Several changes were made to distutils: Some debugging code was
301 removed from util. Fixed the installer used when an external zip
302 program (like WinZip) is not found; the source code for this
303 installer is in Misc/distutils. check_lib() was modified to behave
304 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
305 test for whether installed modules are on sys.path was changed to
306 use both normcase() and normpath().
307
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000308- Several minor bugs were fixed in the xml package (the minidom,
309 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000310
311- The regression test driver (regrtest.py) behavior when invoked with
312 -l changed: It now reports a count of objects that are recognized as
313 garbage but not freed by the garbage collector.
314
Tim Peters989b7b92000-10-16 20:24:53 +0000315- The regression test for the math module was changed to test
316 exceptional behavior when the test is run in verbose mode. Python
317 cannot yet guarantee consistent exception behavior across platforms,
318 so the exception part of test_math is run only in verbose mode, and
319 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000320
321Internals
322
323- PyOS_CheckStack() has been disabled on Win64, where it caused
324 test_sre to fail.
325
326Build issues
327
328- Changed compiler flags, so that gcc is always invoked with -Wall and
329 -Wstrict-prototypes. Users compiling Python with GCC should see
330 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000331 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000332 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000333
Tim Petersa3a3a032000-11-30 05:22:44 +0000334- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000335
336Tools and other miscellany
337
338- The compiler in Tools/compiler was updated to support the new
339 language features introduced in 2.0: extended print statement, list
340 comprehensions, and augmented assignments. The new compiler should
341 also be backwards compatible with Python 1.5.2; the compiler will
342 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000343 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000344
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000345What's new in 2.0 release candidate 1 (since beta 2)?
346=====================================================
347
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000348What is release candidate 1?
349
350We believe that release candidate 1 will fix all known bugs that we
351intend to fix for the 2.0 final release. This release should be a bit
352more stable than the previous betas. We would like to see even more
353widespread testing before the final release, so we are producing this
354release candidate. The final release will be exactly the same unless
355any show-stopping (or brown bag) bugs are found by testers of the
356release candidate.
357
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000358All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000359to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000360
361Core language, builtins, and interpreter
362
363- A bug that caused crashes when __coerce__ was used with augmented
364 assignment, e.g. +=, was fixed.
365
366- Raise ZeroDivisionError when raising zero to a negative number,
367 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
368 power operator and the result of math.pow(0.0, -2.0) will vary by
369 platform. On Linux, it raises a ValueError.
370
371- A bug in Unicode string interpolation was fixed that occasionally
372 caused errors with formats including "%%". For example, the
373 following expression "%% %s" % u"abc" no longer raises a TypeError.
374
375- Compilation of deeply nested expressions raises MemoryError instead
376 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
377
378- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
379 rendering them useless. They are now written in binary mode again.
380
381Standard library
382
383- Keyword arguments are now accepted for most pattern and match object
384 methods in SRE, the standard regular expression engine.
385
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000386- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000387 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000388
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000389- Several bugs in the Unicode handling and error handling in _tkinter
390 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000391
392- Fix memory management errors in Merge() and Tkapp_Call() routines.
393
394- Several changes were made to cStringIO to make it compatible with
395 the file-like object interface and with StringIO. If operations are
396 performed on a closed object, an exception is raised. The truncate
397 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000398 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000399
400- There were many changes made to the linuxaudiodev module and its
401 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000402 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000403
404 Note that this module is named poorly, because it should work
405 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000406 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000407
408 The module now raises exceptions when errors occur instead of
409 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
410 audio) and defines a getptr() method that calls the
411 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
412
413- The library_version attribute, introduced in an earlier beta, was
414 removed because it can not be supported with early versions of the C
415 readline library, which provides no way to determine the version at
416 compile-time.
417
418- The binascii module is now enabled on Win64.
419
Tim Peters46446d62000-10-09 21:19:31 +0000420- tokenize.py no longer suffers "recursion depth" errors when parsing
421 programs with very long string literals.
422
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000423Internals
424
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000425- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000426 which is called when the interpreter starts up to determine where
427 the standard library is installed. These vulnerabilities affect all
428 previous versions of Python and can be exploited by setting very
429 long values for PYTHONHOME or argv[0]. The risk is greatest for a
430 setuid Python script, although use of the wrapper in
431 Misc/setuid-prog.c will eliminate the vulnerability.
432
433- Fixed garbage collection bugs in instance creation that were
434 triggered when errors occurred during initialization. The solution,
435 applied in cPickle and in PyInstance_New(), is to call
436 PyObject_GC_Init() after the initialization of the object's
437 container attributes is complete.
438
439- pyexpat adds definitions of PyModule_AddStringConstant and
440 PyModule_AddObject if the Python version is less than 2.0, which
441 provides compatibility with PyXML on Python 1.5.2.
442
443- If the platform has a bogus definition for LONG_BIT (the number of
444 bits in a long), an error will be reported at compile time.
445
446- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
447 collection crashes and possibly other, unreported crashes.
448
449- Fixed a memory leak in _PyUnicode_Fini().
450
451Build issues
452
453- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000454 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000455 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000456
457- The mmap.PAGESIZE constant is now initialized using sysconf when
458 possible, which eliminates a dependency on -lucb for Reliant UNIX.
459
460- The md5 file should now compile on all platforms.
461
462- The select module now compiles on platforms that do not define
463 POLLRDNORM and related constants.
464
465- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000466 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000467
Jeremy Hylton10921202000-10-09 18:34:12 +0000468- BeOS: A number of changes were made to the build and installation
469 process. ar-fake now operates on a directory of object files.
470 dl_export.h is gone, and its macros now appear on the mwcc command
471 line during build on PPC BeOS.
472
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000473- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000474 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000475
476- Cygwin: Support for shared libraries, Tkinter, and sockets.
477
478- SunOS 4.1.4_JL: Fix test for directory existence in configure.
479
480Tools and other miscellany
481
482- Removed debugging prints from main used with freeze.
483
Tim Peters46446d62000-10-09 21:19:31 +0000484- IDLE auto-indent no longer crashes when it encounters Unicode
485 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000486
487What's new in 2.0 beta 2 (since beta 1)?
488========================================
489
490Core language, builtins, and interpreter
491
Tim Peters482c0212000-09-26 06:33:09 +0000492- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000493 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000494
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000495- Add -h and -V command line options to print the usage message and
496 Python version number and exit immediately.
497
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000498- eval() and exec accept Unicode objects as code parameters.
499
500- getattr() and setattr() now also accept Unicode objects for the
501 attribute name, which are converted to strings using the default
502 encoding before lookup.
503
504- Multiplication on string and Unicode now does proper bounds
505 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
506 string is too long."
507
508- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000509 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000510
Jeremy Hylton1b618592000-09-26 05:32:36 +0000511
512Standard library and extensions
513
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000514- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000515 argument checking; it still takes no arguments.
516
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000517- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000518
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000519- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000520
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000521- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000522
523- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000524 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000525
526- copy: Copy Unicode objects atomically.
527
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000528- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000529
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000530- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000531
Fred Drake67233bc2000-09-26 16:40:27 +0000532- dbm: Add get() and setdefault() methods to dbm object. Add constant
533 `library' to module that names the library used. Added doc strings
534 and method names to error messages. Uses configure to determine
535 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
536 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000537
538- distutils: Update to version 0.9.3.
539
540- dl: Add several dl.RTLD_ constants.
541
542- fpectl: Now supported on FreeBSD.
543
544- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
545 found by the collector will be saved in gc.garbage. This is useful
546 for debugging a program that creates reference cycles.
547
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000548- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000549 of HTTP class. Do not close socket on zero-length response. Do not
550 crash when server sends invalid content-length header.
551
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000552- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000553
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000554- marshal: When reading a short, sign-extend on platforms where shorts
555 are bigger than 16 bits. When reading a long, repair the unportable
556 sign extension that was being done for 64-bit machines. (It assumed
557 that signed right shift sign-extends.)
558
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000559- operator: Add contains(), invert(), __invert__() as aliases for
560 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000561
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000562- os: Add support for popen2() and popen3() on all platforms where
563 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000564
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000565- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000566 clicking on a file in Explorer (or passing the file name to the
567 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000568
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000569- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000570 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000571
572- pickle: Now raises ValueError when an invalid pickle that contains
573 a non-string repr where a string repr was expected. This behavior
574 matches cPickle.
575
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000576- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000577
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000578- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000579
580- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000581 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000582 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000583
584- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000585 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000586
587- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000588 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000589 few cycles during startup since the first call to
590 setdefaultencoding() will initialize the codec registry and the
591 encodings package.
592
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000593- socket: Support for size hint in readlines() method of object returned
594 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000595
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000596- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000597 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000598 is followed by whitespace.
599
Tim Petersa3a3a032000-11-30 05:22:44 +0000600- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000601
602- struct: Check ranges for bytes and shorts.
603
604- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000605 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000606
607- Tkinter: Image objects are now guaranteed to have unique ids. Set
608 event.delta to zero if Tk version doesn't support mousewheel.
609 Removed some debugging prints.
610
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000611- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000612
Fred Drake67233bc2000-09-26 16:40:27 +0000613- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000614 which works around a bug in Norton AntiVirus 2000 that leads directly
615 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000616
617- xml: New version detection code allows PyXML to override standard
618 XML package if PyXML version is greater than 0.6.1.
619
Fred Drake64bb3802000-09-26 16:21:35 +0000620- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
621 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
622 tree only for nodes which are sufficiently interesting to a specific
623 application. Does not provide the HTML-specific extensions. Still
624 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000625
Fred Drake64bb3802000-09-26 16:21:35 +0000626- xml.sax: SAX 2 support for Python, including all the handler
627 interfaces needed to process XML 1.0 compliant XML. Some
628 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000629
Fred Drake64bb3802000-09-26 16:21:35 +0000630- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
631 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000632
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000633
Jeremy Hylton1b618592000-09-26 05:32:36 +0000634C API
635
636- Add three new convenience functions for module initialization --
637 PyModule_AddObject(), PyModule_AddIntConstant(), and
638 PyModule_AddStringConstant().
639
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000640- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000641 removed and add #error to Python.h if NULL isn't defined after
642 #include of stdio.h.
643
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000644- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000645 backwards compatibility (at the source level) with old extensions.
646
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000647- A wrapper API was added for signal() and sigaction(). Instead of
648 either function, always use PyOS_getsig() to get a signal handler
649 and PyOS_setsig() to set one. A new convenience typedef
650 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000651
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000652- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000653 internal data buffer and size of a string object -- or the default
654 encoded version of a Unicode object.
655
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000656- PyString_Size() and PyString_AsString() accept Unicode objects.
657
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000658- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000659 exists). INT_MAX and LONG_MAX will always be defined, even if
660 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000661
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000662- PyFloat_FromString takes a second argument, pend, that was
663 effectively useless. It is now officially useless but preserved for
664 backwards compatibility. If the pend argument is not NULL, *pend is
665 set to NULL.
666
667- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
668 for the attribute name. See note on getattr() above.
669
670- A few bug fixes to argument processing for Unicode.
671 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
672 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
673 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000674 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000675
676- Py_BuildValue accepts B format (for bgen-generated code).
677
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000678
Jeremy Hylton1b618592000-09-26 05:32:36 +0000679Internals
680
681- On Unix, fix code for finding Python installation directory so that
682 it works when argv[0] is a relative path.
683
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000684- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000685 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000686 rather than by generating a copy of the object.
687
Tim Peters482c0212000-09-26 06:33:09 +0000688- Several of the internal Unicode tables are much smaller now, and
689 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000690
Jeremy Hylton97693b02000-09-26 17:42:51 +0000691- In the garbage collector: Fixed bug in collection of tuples. Fixed
692 bug that caused some instances to be removed from the container set
693 while they were still live. Fixed parsing in gc.set_debug() for
694 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000695
696- Fixed refcount problem in instance deallocation that only occurred
697 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
698
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000699- On Windows, getpythonregpath is now protected against null data in
700 registry key.
701
702- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000703 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000704
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000705
Jeremy Hylton1b618592000-09-26 05:32:36 +0000706Build and platform-specific issues
707
708- Better support of GNU Pth via --with-pth configure option.
709
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000710- Python/C API now properly exposed to dynamically-loaded extension
711 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000712
713- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
714 Don't define MS_SYNC to be zero when it is undefined. Added missing
715 prototypes in posixmodule.c.
716
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000717- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000718 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000719
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000720- Fix largefile support on older NetBSD systems and OpenBSD by adding
721 define for TELL64.
722
723
724Tools and other miscellany
725
726- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
727
728- freeze: The modulefinder now works with 2.0 opcodes.
729
Tim Petersa3a3a032000-11-30 05:22:44 +0000730- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000731 Move hackery of sys.argv until after the Tk instance has been
732 created, which allows the application-specific Tkinter
733 initialization to be executed if present; also pass an explicit
734 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000735
Jeremy Hylton1b618592000-09-26 05:32:36 +0000736
737What's new in 2.0 beta 1?
738=========================
739
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000740Source Incompatibilities
741------------------------
742
743None. Note that 1.6 introduced several incompatibilities with 1.5.2,
744such as single-argument append(), connect() and bind(), and changes to
745str(long) and repr(float).
746
747
748Binary Incompatibilities
749------------------------
750
751- Third party extensions built for Python 1.5.x or 1.6 cannot be used
752with Python 2.0; these extensions will have to be rebuilt for Python
7532.0.
754
755- On Windows, attempting to import a third party extension built for
756Python 1.5.x or 1.6 results in an immediate crash; there's not much we
757can do about this. Check your PYTHONPATH environment variable!
758
759- Python bytecode files (*.pyc and *.pyo) are not compatible between
760releases.
761
762
763Overview of Changes Since 1.6
764-----------------------------
765
766There are many new modules (including brand new XML support through
767the xml package, and i18n support through the gettext module); a list
768of all new modules is included below. Lots of bugs have been fixed.
769
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000770The process for making major new changes to the language has changed
771since Python 1.6. Enhancements must now be documented by a Python
772Enhancement Proposal (PEP) before they can be accepted.
773
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000774There are several important syntax enhancements, described in more
775detail below:
776
777 - Augmented assignment, e.g. x += 1
778
779 - List comprehensions, e.g. [x**2 for x in range(10)]
780
781 - Extended import statement, e.g. import Module as Name
782
783 - Extended print statement, e.g. print >> file, "Hello"
784
785Other important changes:
786
787 - Optional collection of cyclical garbage
788
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000789Python Enhancement Proposal (PEP)
790---------------------------------
791
792PEP stands for Python Enhancement Proposal. A PEP is a design
793document providing information to the Python community, or describing
794a new feature for Python. The PEP should provide a concise technical
795specification of the feature and a rationale for the feature.
796
797We intend PEPs to be the primary mechanisms for proposing new
798features, for collecting community input on an issue, and for
799documenting the design decisions that have gone into Python. The PEP
800author is responsible for building consensus within the community and
801documenting dissenting opinions.
802
803The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000804
805Augmented Assignment
806--------------------
807
808This must have been the most-requested feature of the past years!
809Eleven new assignment operators were added:
810
Guido van Rossume905e952000-09-05 12:42:46 +0000811 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000812
813For example,
814
815 A += B
816
817is similar to
818
819 A = A + B
820
821except that A is evaluated only once (relevant when A is something
822like dict[index].attr).
823
824However, if A is a mutable object, A may be modified in place. Thus,
825if A is a number or a string, A += B has the same effect as A = A+B
826(except A is only evaluated once); but if a is a list, A += B has the
827same effect as A.extend(B)!
828
829Classes and built-in object types can override the new operators in
830order to implement the in-place behavior; the not-in-place behavior is
831used automatically as a fallback when an object doesn't implement the
832in-place behavior. For classes, the method name is derived from the
833method name for the corresponding not-in-place operator by inserting
834an 'i' in front of the name, e.g. __iadd__ implements in-place
835__add__.
836
837Augmented assignment was implemented by Thomas Wouters.
838
839
840List Comprehensions
841-------------------
842
843This is a flexible new notation for lists whose elements are computed
844from another list (or lists). The simplest form is:
845
846 [<expression> for <variable> in <sequence>]
847
Guido van Rossum56db0952000-09-06 23:34:25 +0000848For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000849This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000850
851You can also add a condition:
852
853 [<expression> for <variable> in <sequence> if <condition>]
854
855For example, [w for w in words if w == w.lower()] would yield the list
856of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000857than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000858
859You can also have nested for loops and more than one 'if' clause. For
860example, here's a function that flattens a sequence of sequences::
861
862 def flatten(seq):
863 return [x for subseq in seq for x in subseq]
864
865 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
866
867This prints
868
869 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
870
871List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000872Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000873
874
875Extended Import Statement
876-------------------------
877
878Many people have asked for a way to import a module under a different
879name. This can be accomplished like this:
880
881 import foo
882 bar = foo
883 del foo
884
885but this common idiom gets old quickly. A simple extension of the
886import statement now allows this to be written as follows:
887
888 import foo as bar
889
890There's also a variant for 'from ... import':
891
892 from foo import bar as spam
893
894This also works with packages; e.g. you can write this:
895
896 import test.regrtest as regrtest
897
898Note that 'as' is not a new keyword -- it is recognized only in this
899context (this is only possible because the syntax for the import
900statement doesn't involve expressions).
901
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000902Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000903
904
905Extended Print Statement
906------------------------
907
908Easily the most controversial new feature, this extension to the print
909statement adds an option to make the output go to a different file
910than the default sys.stdout.
911
912For example, to write an error message to sys.stderr, you can now
913write:
914
915 print >> sys.stderr, "Error: bad dog!"
916
917As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +0000918evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000919
920 print >> None, "Hello world"
921
922is equivalent to
923
924 print "Hello world"
925
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000926Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000927
928
929Optional Collection of Cyclical Garbage
930---------------------------------------
931
932Python is now equipped with a garbage collector that can hunt down
933cyclical references between Python objects. It's no replacement for
934reference counting; in fact, it depends on the reference counts being
935correct, and decides that a set of objects belong to a cycle if all
936their reference counts can be accounted for from their references to
937each other. This devious scheme was first proposed by Eric Tiedemann,
938and brought to implementation by Neil Schemenauer.
939
940There's a module "gc" that lets you control some parameters of the
941garbage collection. There's also an option to the configure script
942that lets you enable or disable the garbage collection. In 2.0b1,
943it's on by default, so that we (hopefully) can collect decent user
944experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +0000945performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000946off by default in the final 2.0 release.
947
948
949Smaller Changes
950---------------
951
952A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
953map(None, seq1, seq2, ...) when the sequences have the same length;
954i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
955the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000956zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000957
958sys.version_info is a tuple (major, minor, micro, level, serial).
959
960Dictionaries have an odd new method, setdefault(key, default).
961dict.setdefault(key, default) returns dict[key] if it exists; if not,
962it sets dict[key] to default and returns that value. Thus:
963
964 dict.setdefault(key, []).append(item)
965
966does the same work as this common idiom:
967
968 if not dict.has_key(key):
969 dict[key] = []
970 dict[key].append(item)
971
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000972There are two new variants of SyntaxError that are raised for
973indentation-related errors: IndentationError and TabError.
974
975Changed \x to consume exactly two hex digits; see PEP 223. Added \U
976escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +0000977
978The limits on the size of expressions and file in Python source code
979have been raised from 2**16 to 2**32. Previous versions of Python
980were limited because the maximum argument size the Python VM accepted
981was 2**16. This limited the size of object constructor expressions,
982e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
983limit was raised thanks to a patch by Charles Waldman that effectively
984fixes the problem. It is now much more likely that you will be
985limited by available memory than by an arbitrary limit in Python.
986
987The interpreter's maximum recursion depth can be modified by Python
988programs using sys.getrecursionlimit and sys.setrecursionlimit. This
989limit is the maximum number of recursive calls that can be made by
990Python code. The limit exists to prevent infinite recursion from
991overflowing the C stack and causing a core dump. The default value is
9921000. The maximum safe value for a particular platform can be found
993by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000994
995New Modules and Packages
996------------------------
997
998atexit - for registering functions to be called when Python exits.
999
1000imputil - Greg Stein's alternative API for writing custom import
1001hooks.
1002
1003pyexpat - an interface to the Expat XML parser, contributed by Paul
1004Prescod.
1005
1006xml - a new package with XML support code organized (so far) in three
1007subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1008would fill a volume. There's a special feature whereby a
1009user-installed package named _xmlplus overrides the standard
1010xmlpackage; this is intended to give the XML SIG a hook to distribute
1011backwards-compatible updates to the standard xml package.
1012
1013webbrowser - a platform-independent API to launch a web browser.
1014
1015
Guido van Rossume905e952000-09-05 12:42:46 +00001016Changed Modules
1017---------------
1018
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001019array -- new methods for array objects: count, extend, index, pop, and
1020remove
1021
1022binascii -- new functions b2a_hex and a2b_hex that convert between
1023binary data and its hex representation
1024
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001025calendar -- Many new functions that support features including control
1026over which day of the week is the first day, returning strings instead
1027of printing them. Also new symbolic constants for days of week,
1028e.g. MONDAY, ..., SUNDAY.
1029
1030cgi -- FieldStorage objects have a getvalue method that works like a
1031dictionary's get method and returns the value attribute of the object.
1032
1033ConfigParser -- The parser object has new methods has_option,
1034remove_section, remove_option, set, and write. They allow the module
1035to be used for writing config files as well as reading them.
1036
1037ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001038optionally support the RFC 959 REST command.
1039
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001040gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001041
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001042httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1043the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001044
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001045locale -- implement getdefaultlocale for Win32 and Macintosh
1046
1047marshal -- no longer dumps core when marshaling deeply nested or
1048recursive data structures
1049
1050os -- new functions isatty, seteuid, setegid, setreuid, setregid
1051
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001052os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1053support under Unix.
1054
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001055os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001056
1057os.path -- fix semantics of os.path.commonprefix
1058
1059smtplib -- support for sending very long messages
1060
1061socket -- new function getfqdn()
1062
1063readline -- new functions to read, write and truncate history files.
1064The readline section of the library reference manual contains an
1065example.
1066
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001067select -- add interface to poll system call
1068
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001069shutil -- new copyfileobj function
1070
1071SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1072HTTP server.
1073
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001074Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001075
1076urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001077e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001078
1079whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001080
1081
1082Obsolete Modules
1083----------------
1084
1085None. However note that 1.6 made a whole slew of modules obsolete:
1086stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1087poly, zmod, strop, util, whatsound.
1088
1089
1090Changed, New, Obsolete Tools
1091----------------------------
1092
Tim Peters8b092332000-09-05 20:15:25 +00001093None.
Guido van Rossume905e952000-09-05 12:42:46 +00001094
1095
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001096C-level Changes
1097---------------
1098
1099Several cleanup jobs were carried out throughout the source code.
1100
1101All C code was converted to ANSI C; we got rid of all uses of the
1102Py_PROTO() macro, which makes the header files a lot more readable.
1103
1104Most of the portability hacks were moved to a new header file,
1105pyport.h; several other new header files were added and some old
1106header files were removed, in an attempt to create a more rational set
1107of header files. (Few of these ever need to be included explicitly;
1108they are all included by Python.h.)
1109
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001110Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001111and Win64, especially for the new Intel Itanium processor. Mick also
1112added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001113
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001114The C APIs to return an object's size have been update to consistently
1115use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1116previous versions, the abstract interfaces used PyXXX_Length and the
1117concrete interfaces used PyXXX_Size. The old names,
1118e.g. PyObject_Length, are still available for backwards compatibility
1119at the API level, but are deprecated.
1120
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001121The PyOS_CheckStack function has been implemented on Windows by
1122Fredrik Lundh. It prevents Python from failing with a stack overflow
1123on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001124
1125The GC changes resulted in creation of two new slots on object,
1126tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001127the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001128
1129The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001130C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001131
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001132PyErr_Format has been updated to automatically calculate the size of
1133the buffer needed to hold the formatted result string. This change
1134prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001135
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001136New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001137
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001138PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1139that are the same as their non-Ex counterparts except they take an
1140extra flag argument that tells them to close the file when done.
1141
1142XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001143
Tim Peters8b092332000-09-05 20:15:25 +00001144
1145Windows Changes
1146---------------
1147
1148New popen2/popen3/peopen4 in os module (see Changed Modules above).
1149
1150os.popen is much more usable on Windows 95 and 98. See Microsoft
1151Knowledge Base article Q150956. The Win9x workaround described there
1152is implemented by the new w9xpopen.exe helper in the root of your
1153Python installation. Note that Python uses this internally; it is not
1154a standalone program.
1155
1156Administrator privileges are no longer required to install Python
1157on Windows NT or Windows 2000. If you have administrator privileges,
1158Python's registry info will be written under HKEY_LOCAL_MACHINE.
1159Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001160under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001161uses of Python, but will prevent some advanced uses from working
1162(for example, running a Python script as an NT service, or possibly
1163from CGI).
1164
1165[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1166installer; instead, it installs the needed Tcl/Tk files directly in the
1167Python directory. If you already have a Tcl/Tk installation, this
1168wastes some disk space (about 4 Megs) but avoids problems with
1169conflicting Tcl/Tk installations, and makes it much easier for Python
1170to ensure that Tcl/Tk can find all its files.
1171
1172[This was new in 1.6] The Windows installer now installs by default in
1173\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1174
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001175
1176Updates to the changes between 1.5.2 and 1.6
1177--------------------------------------------
1178
1179The 1.6 NEWS file can't be changed after the release is done, so here
1180is some late-breaking news:
1181
1182New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1183and changes to getlocale() and setlocale().
1184
1185The new module is now enabled per default.
1186
1187It is not true that the encodings codecs cannot be used for normal
1188strings: the string.encode() (which is also present on 8-bit strings
1189!) allows using them for 8-bit strings too, e.g. to convert files from
1190cp1252 (Windows) to latin-1 or vice-versa.
1191
1192Japanese codecs are available from Tamito KAJIYAMA:
1193http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1194
1195
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001196======================================================================