blob: e48add572b532fd02edfda7759fe94cb51be788f [file] [log] [blame]
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 Lemburgebb195b2001-01-20 10:34:52 +00006- There is a new Unicode companion to the PyObject_Str() API
7 called PyObject_Unicode(). It behaves in the same way as the
8 former, but assures that the returned value is an Unicode object
9 (applying the usual coercion if necessary).
Marc-André Lemburgad7c98e2001-01-17 17:09:53 +000010
Guido van Rossumf98eda02001-01-17 15:54:45 +000011- The comparison operators support "rich comparison overloading" (PEP
12 207). C extension types can provide a rich comparison function in
13 the new tp_richcompare slot in the type object. The cmp() function
14 and the C function PyObject_Compare() first try the new rich
15 comparison operators before trying the old 3-way comparison. There
16 is also a new C API PyObject_RichCompare() (which also falls back on
17 the old 3-way comparison, but does not constrain the outcome of the
18 rich comparison to a Boolean result).
19
20 The rich comparison function takes two objects (at least one of
21 which is guaranteed to have the type that provided the function) and
22 an integer indicating the opcode, which can be Py_LT, Py_LE, Py_EQ,
23 Py_NE, Py_GT, Py_GE (for <, <=, ==, !=, >, >=), and returns a Python
24 object, which may be NotImplemented (in which case the tp_compare
25 slot function is used as a fallback, if defined).
26
27 Classes can overload individual comparison operators by defining one
28 or more of the methods__lt__, __le__, __eq__, __ne__, __gt__,
Guido van Rossuma88479f2001-01-18 14:28:08 +000029 __ge__. There are no explicit "reflected argument" versions of
30 these; instead, __lt__ and __gt__ are each other's reflection,
31 likewise for__le__ and __ge__; __eq__ and __ne__ are their own
32 reflection (similar at the C level). No other implications are
33 made; in particular, Python does not assume that == is the Boolean
34 inverse of !=, or that < is the Boolean inverse of >=. This makes
35 it possible to define types with partial orderings.
Guido van Rossumf98eda02001-01-17 15:54:45 +000036
37 Classes or types that want to implement (in)equality tests but not
38 the ordering operators (i.e. unordered types) should implement ==
39 and !=, and raise an error for the ordering operators.
40
Guido van Rossuma88479f2001-01-18 14:28:08 +000041 It is possible to define types whose rich comparison results are not
Guido van Rossumf98eda02001-01-17 15:54:45 +000042 Boolean; e.g. a matrix type might want to return a matrix of bits
43 for A < B, giving elementwise comparisons. Such types should ensure
44 that any interpretation of their value in a Boolean context raises
45 an exception, e.g. by defining __nonzero__ (or the tp_nonzero slot
46 at the C level) to always raise an exception.
47
Guido van Rossuma88479f2001-01-18 14:28:08 +000048- Complex numbers use rich comparisons to define == and != but raise
49 an exception for <, <=, > and >=. Unfortunately, this also means
50 that cmp() of two complex numbers raises an exception when the two
51 numbers differ. Since it is not mathematically meaningful to compare
52 complex numbers except for equality, I hope that this doesn't break
53 too much code.
54
Barry Warsaw573b5412001-01-15 20:43:18 +000055- Functions and methods now support getting and setting arbitrarily
56 named attributes (PEP 232). Functions have a new __dict__
57 (a.k.a. func_dict) which hold the function attributes. Methods get
58 and set attributes on their underlying im_func. It is a TypeError
59 to set an attribute on a bound method.
60
Guido van Rossum051e3352001-01-15 19:11:10 +000061- The xrange() object implementation has been improved so that
62 xrange(sys.maxint) can be used on 64-bit platforms. There's still a
63 limitation that in this case len(xrange(sys.maxint)) can't be
64 calculated, but the common idiom "for i in xrange(sys.maxint)" will
65 work fine as long as the index i doesn't actually reach 2**31.
66 (Python uses regular ints for sequence and string indices; fixing
67 that is much more work.)
68
Guido van Rossum1cc8f832001-01-12 16:25:08 +000069- Two changes to from...import:
70
71 1) "from M import X" now works even if M is not a real module; it's
72 basically a getattr() operation with AttributeError exceptions
73 changed into ImportError.
74
75 2) "from M import *" now looks for M.__all__ to decide which names to
76 import; if M.__all__ doesn't exist, it uses M.__dict__.keys() but
77 filters out names starting with '_' as before. Whether or not
78 __all__ exists, there's no restriction on the type of M.
79
Guido van Rossumf61f1662001-01-10 20:13:55 +000080- File objects have a new method, xreadlines(). This is the fastest
81 way to iterate over all lines in a file:
82
83 for line in file.xreadlines():
84 ...do something to line...
85
86 See the xreadlines module (mentioned below) for how to do this for
87 other file-like objects.
88
89- Even if you don't use file.xreadlines(), you may expect a speedup on
90 line-by-line input. The file.readline() method has been optimized
Tim Petersf29b64d2001-01-15 06:33:19 +000091 quite a bit in platform-specific ways: on systems (like Linux) that
92 support flockfile(), getc_unlocked(), and funlockfile(), those are
93 used by default. On systems (like Windows) without getc_unlocked(),
94 a complicated (but still thread-safe) method using fgets() is used by
95 default.
96
97 You can force use of the fgets() method by #define'ing
98 USE_FGETS_IN_GETLINE at build time (it may be faster than
99 getc_unlocked()).
100
101 You can force fgets() not to be used by #define'ing
102 DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
103 test_bufio.py fails -- and let us know if it does!).
104
105- In addition, the fileinput module, while still slower than the other
106 methods on most platforms, has been sped up too, by using
107 file.readlines(sizehint).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000108
109- Support for run-time warnings has been added, including a new
110 command line option (-W) to specify the disposition of warnings.
111 See the description of the warnings module below.
112
113- Extensive changes have been made to the coercion code. This mostly
114 affects extension modules (which can now implement mixed-type
115 numerical operators without having to use coercion), but
116 occasionally, in boundary cases the coercion semantics have changed
117 subtly. Since this was a terrible gray area of the language, this
Guido van Rossumae72d872001-01-11 15:00:14 +0000118 is considered an improvement. Also note that __rcmp__ is no longer
Guido van Rossumf61f1662001-01-10 20:13:55 +0000119 supported -- instead of calling __rcmp__, __cmp__ is called with
Guido van Rossuma88479f2001-01-18 14:28:08 +0000120 reflected arguments.
Guido van Rossumf61f1662001-01-10 20:13:55 +0000121
Guido van Rossumf98eda02001-01-17 15:54:45 +0000122- In connection with the coercion changes, a new built-in singleton
123 object, NotImplemented is defined. This can be returned for
124 operations that wish to indicate they are not implemented for a
125 particular combination of arguments. From C, this is
126 Py_NotImplemented.
127
Martin v. Löwisbe4c0f52001-01-04 20:30:56 +0000128- The interpreter accepts now bytecode files on the command line even
129 if they do not have a .pyc or .pyo extension. On Linux, after executing
130
131 echo ':pyc:M::\x87\xc6\x0d\x0a::/usr/local/bin/python:' > /proc/sys/fs/binfmt_misc/register
132
133 any byte code file can be used as an executable (i.e. as an argument
134 to execve(2)).
135
Tim Peters9940b802000-12-01 07:59:35 +0000136- %[xXo] formats of negative Python longs now produce a sign
Tim Petersa3a3a032000-11-30 05:22:44 +0000137 character. In 1.6 and earlier, they never produced a sign,
138 and raised an error if the value of the long was too large
139 to fit in a Python int. In 2.0, they produced a sign if and
140 only if too large to fit in an int. This was inconsistent
141 across platforms (because the size of an int varies across
142 platforms), and inconsistent with hex() and oct(). Example:
143
144 >>> "%x" % -0x42L
Tim Peters9940b802000-12-01 07:59:35 +0000145 '-42' # in 2.1
Tim Petersa3a3a032000-11-30 05:22:44 +0000146 'ffffffbe' # in 2.0 and before, on 32-bit machines
147 >>> hex(-0x42L)
148 '-0x42L' # in all versions of Python
149
Tim Peters9940b802000-12-01 07:59:35 +0000150 The behavior of %d formats for negative Python longs remains
151 the same as in 2.0 (although in 1.6 and before, they raised
152 an error if the long didn't fit in a Python int).
153
154 %u formats don't make sense for Python longs, but are allowed
155 and treated the same as %d in 2.1. In 2.0, a negative long
156 formatted via %u produced a sign if and only if too large to
157 fit in an int. In 1.6 and earlier, a negative long formatted
158 via %u raised an error if it was too big to fit in an int.
159
Guido van Rossum3661d392000-12-12 22:10:31 +0000160- Dictionary objects have an odd new method, popitem(). This removes
161 an arbitrary item from the dictionary and returns it (in the form of
162 a (key, value) pair). This can be useful for algorithms that use a
163 dictionary as a bag of "to do" items and repeatedly need to pick one
164 item. Such algorithms normally end up running in quadratic time;
165 using popitem() they can usually be made to run in linear time.
166
Tim Peters36cdad12000-12-29 02:06:45 +0000167Standard library
168
Thomas Woutersfe385252001-01-19 23:16:56 +0000169- In the time module, the time argument to the functions strftime,
170 localtime, gmtime, asctime and ctime is now optional, defaulting to
171 the current time (in the local timezone).
172
Guido van Rossumda91f222001-01-15 16:36:08 +0000173- The ftplib module now defaults to passive mode, which is deemed a
174 more useful default given that clients are often inside firewalls
175 these days. Note that this could break if ftplib is used to connect
176 to a *server* that is inside a firewall, from outside; this is
177 expected to be a very rare situation. To fix that, you can call
178 ftp.set_pasv(0).
179
Martin v. Löwis10a27872001-01-13 09:54:41 +0000180- The module site now treats .pth files not only for path configuration,
181 but also supports extensions to the initialization code: Lines starting
182 with import are executed.
183
Guido van Rossumf61f1662001-01-10 20:13:55 +0000184- There's a new module, warnings, which implements a mechanism for
185 issuing and filtering warnings. There are some new built-in
186 exceptions that serve as warning categories, and a new command line
187 option, -W, to control warnings (e.g. -Wi ignores all warnings, -We
188 turns warnings into errors). warnings.warn(message[, category])
189 issues a warning message; this can also be called from C as
190 PyErr_Warn(category, message).
191
192- A new module xreadlines was added. This exports a single factory
193 function, xreadlines(). The intention is that this code is the
194 absolutely fastest way to iterate over all lines in an open
195 file(-like) object:
196
197 import xreadlines
198 for line in xreadlines.xreadlines(file):
199 ...do something to line...
200
201 This is equivalent to the previous the speed record holder using
202 file.readlines(sizehint). Note that if file is a real file object
203 (as opposed to a file-like object), this is equivalent:
204
205 for line in file.xreadlines():
206 ...do something to line...
207
Tim Peters36cdad12000-12-29 02:06:45 +0000208- The bisect module has new functions bisect_left, insort_left,
209 bisect_right and insort_right. The old names bisect and insort
210 are now aliases for bisect_right and insort_right. XXX_right
211 and XXX_left methods differ in what happens when the new element
212 compares equal to one or more elements already in the list: the
213 XXX_left methods insert to the left, the XXX_right methods to the
Tim Peters742bb6f2001-01-05 08:05:32 +0000214 right. Code that doesn't care where equal elements end up should
215 continue to use the old, short names ("bisect" and "insort").
Tim Peters36cdad12000-12-29 02:06:45 +0000216
Andrew M. Kuchlingf6f3a892001-01-13 14:53:34 +0000217- The new curses.panel module wraps the panel library that forms part
218 of SYSV curses and ncurses. Contributed by Thomas Gellekum.
219
Guido van Rossumf61f1662001-01-10 20:13:55 +0000220- The SocketServer module now sets the allow_reuse_address flag by
221 default in the TCPServer class.
222
223- A new function, sys._getframe(), returns the stack frame pointer of
224 the caller. This is intended only as a building block for
225 higher-level mechanisms such as string interpolation.
226
227Build issues
228
Guido van Rossum1e33bdc2001-01-23 03:17:00 +0000229- For Unix (and Unix-compatible) builds, configuration and building of
230 extension modules is now greatly automated. Rather than having to
231 edit the Modules/Setup file to indicate which modules should be
232 built and where their include files and libraries are, a
233 distutils-based setup.py script now takes care of building most
234 extension modules. All extension modules built this way are built
235 as shared libraries. Only a few modules that must be linked
236 statically are still listed in the Setup file; you won't need to
237 edit their configuration.
238
239- Python should now build out of the box on Cygwin. If it doesn't,
240 mail to Jason Tishler (jlt63 at users.sourceforge.net).
Guido van Rossumf61f1662001-01-10 20:13:55 +0000241
242- Python now always uses its own (renamed) implementation of getopt()
243 -- there's too much variation among C library getopt()
244 implementations.
245
246- C++ compilers are better supported; the CXX macro is always set to a
247 C++ compiler if one is found.
Tim Peters36cdad12000-12-29 02:06:45 +0000248
Tim Petersd92dfe02000-12-12 01:18:41 +0000249Windows changes
250
251- select module: By default under Windows, a select() call
252 can specify no more than 64 sockets. Python now boosts
253 this Microsoft default to 512. If you need even more than
254 that, see the MS docs (you'll need to #define FD_SETSIZE
255 and recompile Python from source).
256
Guido van Rossumf61f1662001-01-10 20:13:55 +0000257- Support for Windows 3.1, DOS and OS/2 is gone. The Lib/dos-8x3
258 subdirectory is no more!
259
Tim Petersa3a3a032000-11-30 05:22:44 +0000260
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000261What's New in Python 2.0?
Fred Drake1a640502000-10-16 20:27:25 +0000262=========================
Guido van Rossum61000331997-08-15 04:39:58 +0000263
Guido van Rossum8ed602b2000-09-01 22:34:33 +0000264Below is a list of all relevant changes since release 1.6. Older
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000265changes are in the file HISTORY. If you are making the jump directly
266from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the
267HISTORY file! Many important changes listed there.
Guido van Rossum61000331997-08-15 04:39:58 +0000268
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000269Alternatively, a good overview of the changes between 1.5.2 and 2.0 is
270the document "What's New in Python 2.0" by Kuchling and Moshe Zadka:
271http://starship.python.net/crew/amk/python/writing/new-python/.
Guido van Rossum1f83cce1997-10-06 21:04:35 +0000272
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000273--Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)
Guido van Rossum437cfe81999-04-08 20:17:57 +0000274
275======================================================================
276
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000277What's new in 2.0 (since release candidate 1)?
278==============================================
279
280Standard library
281
282- The copy_reg module was modified to clarify its intended use: to
283 register pickle support for extension types, not for classes.
284 pickle() will raise a TypeError if it is passed a class.
285
286- Fixed a bug in gettext's "normalize and expand" code that prevented
287 it from finding an existing .mo file.
288
289- Restored support for HTTP/0.9 servers in httplib.
290
Tim Peters989b7b92000-10-16 20:24:53 +0000291- The math module was changed to stop raising OverflowError in case of
292 underflow, and return 0 instead in underflow cases. Whether Python
293 used to raise OverflowError in case of underflow was platform-
294 dependent (it did when the platform math library set errno to ERANGE
295 on underflow).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000296
297- Fixed a bug in StringIO that occurred when the file position was not
298 at the end of the file and write() was called with enough data to
299 extend past the end of the file.
300
301- Fixed a bug that caused Tkinter error messages to get lost on
302 Windows. The bug was fixed by replacing direct use of
303 interp->result with Tcl_GetStringResult(interp).
304
305- Fixed bug in urllib2 that caused it to fail when it received an HTTP
306 redirect response.
307
308- Several changes were made to distutils: Some debugging code was
309 removed from util. Fixed the installer used when an external zip
310 program (like WinZip) is not found; the source code for this
311 installer is in Misc/distutils. check_lib() was modified to behave
312 more like AC_CHECK_LIB by add other_libraries() as a parameter. The
313 test for whether installed modules are on sys.path was changed to
314 use both normcase() and normpath().
315
Jeremy Hyltond867a2c2000-10-16 20:41:38 +0000316- Several minor bugs were fixed in the xml package (the minidom,
317 pulldom, expatreader, and saxutils modules).
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000318
319- The regression test driver (regrtest.py) behavior when invoked with
320 -l changed: It now reports a count of objects that are recognized as
321 garbage but not freed by the garbage collector.
322
Tim Peters989b7b92000-10-16 20:24:53 +0000323- The regression test for the math module was changed to test
324 exceptional behavior when the test is run in verbose mode. Python
325 cannot yet guarantee consistent exception behavior across platforms,
326 so the exception part of test_math is run only in verbose mode, and
327 may fail on your platform.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000328
329Internals
330
331- PyOS_CheckStack() has been disabled on Win64, where it caused
332 test_sre to fail.
333
334Build issues
335
336- Changed compiler flags, so that gcc is always invoked with -Wall and
337 -Wstrict-prototypes. Users compiling Python with GCC should see
338 exactly one warning, except if they have passed configure the
Tim Peters989b7b92000-10-16 20:24:53 +0000339 --with-pydebug flag. The expected warning is for getopt() in
Tim Petersadfb94f2000-10-16 20:51:33 +0000340 Modules/main.c. This warning will be fixed for Python 2.1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000341
Tim Petersa3a3a032000-11-30 05:22:44 +0000342- Fixed configure to add -threads argument during linking on OSF1.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000343
344Tools and other miscellany
345
346- The compiler in Tools/compiler was updated to support the new
347 language features introduced in 2.0: extended print statement, list
348 comprehensions, and augmented assignments. The new compiler should
349 also be backwards compatible with Python 1.5.2; the compiler will
350 always generate code for the version of the interpreter it runs
Tim Petersa3a3a032000-11-30 05:22:44 +0000351 under.
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000352
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000353What's new in 2.0 release candidate 1 (since beta 2)?
354=====================================================
355
Jeremy Hylton6040aaa2000-10-09 21:27:22 +0000356What is release candidate 1?
357
358We believe that release candidate 1 will fix all known bugs that we
359intend to fix for the 2.0 final release. This release should be a bit
360more stable than the previous betas. We would like to see even more
361widespread testing before the final release, so we are producing this
362release candidate. The final release will be exactly the same unless
363any show-stopping (or brown bag) bugs are found by testers of the
364release candidate.
365
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000366All the changes since the last beta release are bug fixes or changes
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000367to support building Python for specific platforms.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000368
369Core language, builtins, and interpreter
370
371- A bug that caused crashes when __coerce__ was used with augmented
372 assignment, e.g. +=, was fixed.
373
374- Raise ZeroDivisionError when raising zero to a negative number,
375 e.g. 0.0 ** -2.0. Note that math.pow is unrelated to the builtin
376 power operator and the result of math.pow(0.0, -2.0) will vary by
377 platform. On Linux, it raises a ValueError.
378
379- A bug in Unicode string interpolation was fixed that occasionally
380 caused errors with formats including "%%". For example, the
381 following expression "%% %s" % u"abc" no longer raises a TypeError.
382
383- Compilation of deeply nested expressions raises MemoryError instead
384 of SyntaxError, e.g. eval("[" * 50 + "]" * 50).
385
386- In 2.0b2 on Windows, the interpreter wrote .pyc files in text mode,
387 rendering them useless. They are now written in binary mode again.
388
389Standard library
390
391- Keyword arguments are now accepted for most pattern and match object
392 methods in SRE, the standard regular expression engine.
393
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000394- In SRE, fixed error with negative lookahead and lookbehind that
Jeremy Hylton32e20ff2000-10-09 19:48:11 +0000395 manifested itself as a runtime error in patterns like "(?<!abc)(def)".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000396
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000397- Several bugs in the Unicode handling and error handling in _tkinter
398 were fixed.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000399
400- Fix memory management errors in Merge() and Tkapp_Call() routines.
401
402- Several changes were made to cStringIO to make it compatible with
403 the file-like object interface and with StringIO. If operations are
404 performed on a closed object, an exception is raised. The truncate
405 method now accepts a position argument and readline accepts a size
Tim Petersa3a3a032000-11-30 05:22:44 +0000406 argument.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000407
408- There were many changes made to the linuxaudiodev module and its
409 test suite; as a result, a short, unexpected audio sample should now
Tim Petersa3a3a032000-11-30 05:22:44 +0000410 play when the regression test is run.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000411
412 Note that this module is named poorly, because it should work
413 correctly on any platform that supports the Open Sound System
Tim Petersa3a3a032000-11-30 05:22:44 +0000414 (OSS).
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000415
416 The module now raises exceptions when errors occur instead of
417 crashing. It also defines the AFMT_A_LAW format (logarithmic A-law
418 audio) and defines a getptr() method that calls the
419 SNDCTL_DSP_GETxPTR ioctl defined in the OSS Programmer's Guide.
420
421- The library_version attribute, introduced in an earlier beta, was
422 removed because it can not be supported with early versions of the C
423 readline library, which provides no way to determine the version at
424 compile-time.
425
426- The binascii module is now enabled on Win64.
427
Tim Peters46446d62000-10-09 21:19:31 +0000428- tokenize.py no longer suffers "recursion depth" errors when parsing
429 programs with very long string literals.
430
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000431Internals
432
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000433- Fixed several buffer overflow vulnerabilities in calculate_path(),
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000434 which is called when the interpreter starts up to determine where
435 the standard library is installed. These vulnerabilities affect all
436 previous versions of Python and can be exploited by setting very
437 long values for PYTHONHOME or argv[0]. The risk is greatest for a
438 setuid Python script, although use of the wrapper in
439 Misc/setuid-prog.c will eliminate the vulnerability.
440
441- Fixed garbage collection bugs in instance creation that were
442 triggered when errors occurred during initialization. The solution,
443 applied in cPickle and in PyInstance_New(), is to call
444 PyObject_GC_Init() after the initialization of the object's
445 container attributes is complete.
446
447- pyexpat adds definitions of PyModule_AddStringConstant and
448 PyModule_AddObject if the Python version is less than 2.0, which
449 provides compatibility with PyXML on Python 1.5.2.
450
451- If the platform has a bogus definition for LONG_BIT (the number of
452 bits in a long), an error will be reported at compile time.
453
454- Fix bugs in _PyTuple_Resize() which caused hard-to-interpret garbage
455 collection crashes and possibly other, unreported crashes.
456
457- Fixed a memory leak in _PyUnicode_Fini().
458
459Build issues
460
461- configure now accepts a --with-suffix option that specifies the
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000462 executable suffix. This is useful for builds on Cygwin and Mac OS
Tim Petersa3a3a032000-11-30 05:22:44 +0000463 X, for example.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000464
465- The mmap.PAGESIZE constant is now initialized using sysconf when
466 possible, which eliminates a dependency on -lucb for Reliant UNIX.
467
468- The md5 file should now compile on all platforms.
469
470- The select module now compiles on platforms that do not define
471 POLLRDNORM and related constants.
472
473- Darwin (Mac OS X): Initial support for static builds on this
Tim Petersa3a3a032000-11-30 05:22:44 +0000474 platform.
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000475
Jeremy Hylton10921202000-10-09 18:34:12 +0000476- BeOS: A number of changes were made to the build and installation
477 process. ar-fake now operates on a directory of object files.
478 dl_export.h is gone, and its macros now appear on the mwcc command
479 line during build on PPC BeOS.
480
Jeremy Hyltond6e20232000-10-16 20:08:38 +0000481- Platform directory in lib/python2.0 is "plat-beos5" (or
Jeremy Hylton10921202000-10-09 18:34:12 +0000482 "plat-beos4", if building on BeOS 4.5), rather than "plat-beos".
Jeremy Hyltoned9e6442000-10-09 18:26:42 +0000483
484- Cygwin: Support for shared libraries, Tkinter, and sockets.
485
486- SunOS 4.1.4_JL: Fix test for directory existence in configure.
487
488Tools and other miscellany
489
490- Removed debugging prints from main used with freeze.
491
Tim Peters46446d62000-10-09 21:19:31 +0000492- IDLE auto-indent no longer crashes when it encounters Unicode
493 characters.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000494
495What's new in 2.0 beta 2 (since beta 1)?
496========================================
497
498Core language, builtins, and interpreter
499
Tim Peters482c0212000-09-26 06:33:09 +0000500- Add support for unbounded ints in %d,i,u,x,X,o formats; for example
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000501 "%d" % 2L**64 == "18446744073709551616".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000502
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000503- Add -h and -V command line options to print the usage message and
504 Python version number and exit immediately.
505
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000506- eval() and exec accept Unicode objects as code parameters.
507
508- getattr() and setattr() now also accept Unicode objects for the
509 attribute name, which are converted to strings using the default
510 encoding before lookup.
511
512- Multiplication on string and Unicode now does proper bounds
513 checking; e.g. 'a' * 65536 * 65536 will raise ValueError, "repeated
514 string is too long."
515
516- Better error message when continue is found in try statement in a
Tim Petersa3a3a032000-11-30 05:22:44 +0000517 loop.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000518
Jeremy Hylton1b618592000-09-26 05:32:36 +0000519
520Standard library and extensions
521
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000522- array: reverse() method of array now works. buffer_info() now does
Jeremy Hylton1b618592000-09-26 05:32:36 +0000523 argument checking; it still takes no arguments.
524
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000525- asyncore/asynchat: Included most recent version from Sam Rushing.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000526
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000527- cgi: Accept '&' or ';' as separator characters when parsing form data.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000528
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000529- CGIHTTPServer: Now works on Windows (and perhaps even Mac).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000530
531- ConfigParser: When reading the file, options spelled in upper case
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000532 letters are now correctly converted to lowercase.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000533
534- copy: Copy Unicode objects atomically.
535
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000536- cPickle: Fail gracefully when copy_reg can't be imported.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000537
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000538- cStringIO: Implemented readlines() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000539
Fred Drake67233bc2000-09-26 16:40:27 +0000540- dbm: Add get() and setdefault() methods to dbm object. Add constant
541 `library' to module that names the library used. Added doc strings
542 and method names to error messages. Uses configure to determine
543 which ndbm.h file to include; Berkeley DB's nbdm and GDBM's ndbm is
544 now available options.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000545
546- distutils: Update to version 0.9.3.
547
548- dl: Add several dl.RTLD_ constants.
549
550- fpectl: Now supported on FreeBSD.
551
552- gc: Add DEBUG_SAVEALL option. When enabled all garbage objects
553 found by the collector will be saved in gc.garbage. This is useful
554 for debugging a program that creates reference cycles.
555
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000556- httplib: Three changes: Restore support for set_debuglevel feature
Jeremy Hylton1b618592000-09-26 05:32:36 +0000557 of HTTP class. Do not close socket on zero-length response. Do not
558 crash when server sends invalid content-length header.
559
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000560- mailbox: Mailbox class conforms better to qmail specifications.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000561
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000562- marshal: When reading a short, sign-extend on platforms where shorts
563 are bigger than 16 bits. When reading a long, repair the unportable
564 sign extension that was being done for 64-bit machines. (It assumed
565 that signed right shift sign-extends.)
566
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000567- operator: Add contains(), invert(), __invert__() as aliases for
568 __contains__(), inv(), and __inv__() respectively.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000569
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000570- os: Add support for popen2() and popen3() on all platforms where
571 fork() exists. (popen4() is still in the works.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000572
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000573- os: (Windows only:) Add startfile() function that acts like double-
Tim Peters482c0212000-09-26 06:33:09 +0000574 clicking on a file in Explorer (or passing the file name to the
575 DOS "start" command).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000576
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000577- os.path: (Windows, DOS:) Treat trailing colon correctly in
Tim Peters482c0212000-09-26 06:33:09 +0000578 os.path.join. os.path.join("a:", "b") yields "a:b".
Jeremy Hylton1b618592000-09-26 05:32:36 +0000579
580- pickle: Now raises ValueError when an invalid pickle that contains
581 a non-string repr where a string repr was expected. This behavior
582 matches cPickle.
583
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000584- posixfile: Remove broken __del__() method.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000585
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000586- py_compile: support CR+LF line terminators in source file.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000587
588- readline: Does not immediately exit when ^C is hit when readline and
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000589 threads are configured. Adds definition of rl_library_version. (The
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000590 latter addition requires GNU readline 2.2 or later.)
Jeremy Hylton1b618592000-09-26 05:32:36 +0000591
592- rfc822: Domain literals returned by AddrlistClass method
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000593 getdomainliteral() are now properly wrapped in brackets.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000594
595- site: sys.setdefaultencoding() should only be called in case the
Tim Peters482c0212000-09-26 06:33:09 +0000596 standard default encoding ("ascii") is changed. This saves quite a
Jeremy Hylton1b618592000-09-26 05:32:36 +0000597 few cycles during startup since the first call to
598 setdefaultencoding() will initialize the codec registry and the
599 encodings package.
600
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000601- socket: Support for size hint in readlines() method of object returned
602 by makefile().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000603
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000604- sre: Added experimental expand() method to match objects. Does not
Jeremy Hylton625915e2000-10-02 13:43:33 +0000605 use buffer interface on Unicode strings. Does not hang if group id
Jeremy Hylton1b618592000-09-26 05:32:36 +0000606 is followed by whitespace.
607
Tim Petersa3a3a032000-11-30 05:22:44 +0000608- StringIO: Size hint in readlines() is now supported as documented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000609
610- struct: Check ranges for bytes and shorts.
611
612- urllib: Improved handling of win32 proxy settings. Fixed quote and
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000613 quote_plus functions so that the always encode a comma.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000614
615- Tkinter: Image objects are now guaranteed to have unique ids. Set
616 event.delta to zero if Tk version doesn't support mousewheel.
617 Removed some debugging prints.
618
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000619- UserList: now implements __contains__().
Jeremy Hylton1b618592000-09-26 05:32:36 +0000620
Fred Drake67233bc2000-09-26 16:40:27 +0000621- webbrowser: On Windows, use os.startfile() instead of os.popen(),
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000622 which works around a bug in Norton AntiVirus 2000 that leads directly
623 to a Blue Screen freeze.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000624
625- xml: New version detection code allows PyXML to override standard
626 XML package if PyXML version is greater than 0.6.1.
627
Fred Drake64bb3802000-09-26 16:21:35 +0000628- xml.dom: DOM level 1 support for basic XML. Includes xml.dom.minidom
629 (conventional DOM), and xml.dom.pulldom, which allows building the DOM
630 tree only for nodes which are sufficiently interesting to a specific
631 application. Does not provide the HTML-specific extensions. Still
632 undocumented.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000633
Fred Drake64bb3802000-09-26 16:21:35 +0000634- xml.sax: SAX 2 support for Python, including all the handler
635 interfaces needed to process XML 1.0 compliant XML. Some
636 documentation is already available.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000637
Fred Drake64bb3802000-09-26 16:21:35 +0000638- pyexpat: Renamed to xml.parsers.expat since this is part of the new,
639 packagized XML support.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000640
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000641
Jeremy Hylton1b618592000-09-26 05:32:36 +0000642C API
643
644- Add three new convenience functions for module initialization --
645 PyModule_AddObject(), PyModule_AddIntConstant(), and
646 PyModule_AddStringConstant().
647
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000648- Cleaned up definition of NULL in C source code; all definitions were
Jeremy Hylton1b618592000-09-26 05:32:36 +0000649 removed and add #error to Python.h if NULL isn't defined after
650 #include of stdio.h.
651
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000652- Py_PROTO() macros that were removed in 2.0b1 have been restored for
Jeremy Hylton1b618592000-09-26 05:32:36 +0000653 backwards compatibility (at the source level) with old extensions.
654
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000655- A wrapper API was added for signal() and sigaction(). Instead of
656 either function, always use PyOS_getsig() to get a signal handler
657 and PyOS_setsig() to set one. A new convenience typedef
658 PyOS_sighandler_t is defined for the type of signal handlers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000659
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000660- Add PyString_AsStringAndSize() function that provides access to the
Jeremy Hylton1b618592000-09-26 05:32:36 +0000661 internal data buffer and size of a string object -- or the default
662 encoded version of a Unicode object.
663
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000664- PyString_Size() and PyString_AsString() accept Unicode objects.
665
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000666- The standard header <limits.h> is now included by Python.h (if it
Fred Drake64bb3802000-09-26 16:21:35 +0000667 exists). INT_MAX and LONG_MAX will always be defined, even if
668 <limits.h> is not available.
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000669
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000670- PyFloat_FromString takes a second argument, pend, that was
671 effectively useless. It is now officially useless but preserved for
672 backwards compatibility. If the pend argument is not NULL, *pend is
673 set to NULL.
674
675- PyObject_GetAttr() and PyObject_SetAttr() now accept Unicode objects
676 for the attribute name. See note on getattr() above.
677
678- A few bug fixes to argument processing for Unicode.
679 PyArg_ParseTupleAndKeywords() now accepts "es#" and "es".
680 PyArg_Parse() special cases "s#" for Unicode objects; it returns a
681 pointer to the default encoded string data instead of to the raw
Tim Petersa3a3a032000-11-30 05:22:44 +0000682 UTF-16.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000683
684- Py_BuildValue accepts B format (for bgen-generated code).
685
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000686
Jeremy Hylton1b618592000-09-26 05:32:36 +0000687Internals
688
689- On Unix, fix code for finding Python installation directory so that
690 it works when argv[0] is a relative path.
691
Andrew M. Kuchlinga1099be2000-12-15 01:16:43 +0000692- Added a true unicode_internal_encode() function and fixed the
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000693 unicode_internal_decode function() to support Unicode objects directly
Jeremy Hylton1b618592000-09-26 05:32:36 +0000694 rather than by generating a copy of the object.
695
Tim Peters482c0212000-09-26 06:33:09 +0000696- Several of the internal Unicode tables are much smaller now, and
697 the source code should be much friendlier to weaker compilers.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000698
Jeremy Hylton97693b02000-09-26 17:42:51 +0000699- In the garbage collector: Fixed bug in collection of tuples. Fixed
700 bug that caused some instances to be removed from the container set
701 while they were still live. Fixed parsing in gc.set_debug() for
702 platforms where sizeof(long) > sizeof(int).
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000703
704- Fixed refcount problem in instance deallocation that only occurred
705 when Py_REF_DEBUG was defined and Py_TRACE_REFS was not.
706
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000707- On Windows, getpythonregpath is now protected against null data in
708 registry key.
709
710- On Unix, create .pyc/.pyo files with O_EXCL flag to avoid a race
Tim Petersa3a3a032000-11-30 05:22:44 +0000711 condition.
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000712
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000713
Jeremy Hylton1b618592000-09-26 05:32:36 +0000714Build and platform-specific issues
715
716- Better support of GNU Pth via --with-pth configure option.
717
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000718- Python/C API now properly exposed to dynamically-loaded extension
719 modules on Reliant UNIX.
Jeremy Hylton1b618592000-09-26 05:32:36 +0000720
721- Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c:
722 Don't define MS_SYNC to be zero when it is undefined. Added missing
723 prototypes in posixmodule.c.
724
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000725- Improved support for HP-UX build. Threads should now be correctly
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000726 configured (on HP-UX 10.20 and 11.00).
Jeremy Hylton1b618592000-09-26 05:32:36 +0000727
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000728- Fix largefile support on older NetBSD systems and OpenBSD by adding
729 define for TELL64.
730
731
732Tools and other miscellany
733
734- ftpmirror: Call to main() is wrapped in if __name__ == "__main__".
735
736- freeze: The modulefinder now works with 2.0 opcodes.
737
Tim Petersa3a3a032000-11-30 05:22:44 +0000738- IDLE:
Jeremy Hyltonfa2e2c12000-09-26 16:31:30 +0000739 Move hackery of sys.argv until after the Tk instance has been
740 created, which allows the application-specific Tkinter
741 initialization to be executed if present; also pass an explicit
742 className parameter to the Tk() constructor.
Fred Drake64bb3802000-09-26 16:21:35 +0000743
Jeremy Hylton1b618592000-09-26 05:32:36 +0000744
745What's new in 2.0 beta 1?
746=========================
747
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000748Source Incompatibilities
749------------------------
750
751None. Note that 1.6 introduced several incompatibilities with 1.5.2,
752such as single-argument append(), connect() and bind(), and changes to
753str(long) and repr(float).
754
755
756Binary Incompatibilities
757------------------------
758
759- Third party extensions built for Python 1.5.x or 1.6 cannot be used
760with Python 2.0; these extensions will have to be rebuilt for Python
7612.0.
762
763- On Windows, attempting to import a third party extension built for
764Python 1.5.x or 1.6 results in an immediate crash; there's not much we
765can do about this. Check your PYTHONPATH environment variable!
766
767- Python bytecode files (*.pyc and *.pyo) are not compatible between
768releases.
769
770
771Overview of Changes Since 1.6
772-----------------------------
773
774There are many new modules (including brand new XML support through
775the xml package, and i18n support through the gettext module); a list
776of all new modules is included below. Lots of bugs have been fixed.
777
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000778The process for making major new changes to the language has changed
779since Python 1.6. Enhancements must now be documented by a Python
780Enhancement Proposal (PEP) before they can be accepted.
781
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000782There are several important syntax enhancements, described in more
783detail below:
784
785 - Augmented assignment, e.g. x += 1
786
787 - List comprehensions, e.g. [x**2 for x in range(10)]
788
789 - Extended import statement, e.g. import Module as Name
790
791 - Extended print statement, e.g. print >> file, "Hello"
792
793Other important changes:
794
795 - Optional collection of cyclical garbage
796
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000797Python Enhancement Proposal (PEP)
798---------------------------------
799
800PEP stands for Python Enhancement Proposal. A PEP is a design
801document providing information to the Python community, or describing
802a new feature for Python. The PEP should provide a concise technical
803specification of the feature and a rationale for the feature.
804
805We intend PEPs to be the primary mechanisms for proposing new
806features, for collecting community input on an issue, and for
807documenting the design decisions that have gone into Python. The PEP
808author is responsible for building consensus within the community and
809documenting dissenting opinions.
810
811The PEPs are available at http://python.sourceforge.net/peps/.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000812
813Augmented Assignment
814--------------------
815
816This must have been the most-requested feature of the past years!
817Eleven new assignment operators were added:
818
Guido van Rossume905e952000-09-05 12:42:46 +0000819 += -= *= /= %= **= <<= >>= &= ^= |=
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000820
821For example,
822
823 A += B
824
825is similar to
826
827 A = A + B
828
829except that A is evaluated only once (relevant when A is something
830like dict[index].attr).
831
832However, if A is a mutable object, A may be modified in place. Thus,
833if A is a number or a string, A += B has the same effect as A = A+B
834(except A is only evaluated once); but if a is a list, A += B has the
835same effect as A.extend(B)!
836
837Classes and built-in object types can override the new operators in
838order to implement the in-place behavior; the not-in-place behavior is
839used automatically as a fallback when an object doesn't implement the
840in-place behavior. For classes, the method name is derived from the
841method name for the corresponding not-in-place operator by inserting
842an 'i' in front of the name, e.g. __iadd__ implements in-place
843__add__.
844
845Augmented assignment was implemented by Thomas Wouters.
846
847
848List Comprehensions
849-------------------
850
851This is a flexible new notation for lists whose elements are computed
852from another list (or lists). The simplest form is:
853
854 [<expression> for <variable> in <sequence>]
855
Guido van Rossum56db0952000-09-06 23:34:25 +0000856For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9].
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000857This is more efficient than a for loop with a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000858
859You can also add a condition:
860
861 [<expression> for <variable> in <sequence> if <condition>]
862
863For example, [w for w in words if w == w.lower()] would yield the list
864of words that contain no uppercase characters. This is more efficient
Guido van Rossumf62ed9c2000-09-26 11:16:10 +0000865than a for loop with an if statement and a list.append() call.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000866
867You can also have nested for loops and more than one 'if' clause. For
868example, here's a function that flattens a sequence of sequences::
869
870 def flatten(seq):
871 return [x for subseq in seq for x in subseq]
872
873 flatten([[0], [1,2,3], [4,5], [6,7,8,9], []])
874
875This prints
876
877 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
878
879List comprehensions originated as a patch set from Greg Ewing; Skip
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000880Montanaro and Thomas Wouters also contributed. Described by PEP 202.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000881
882
883Extended Import Statement
884-------------------------
885
886Many people have asked for a way to import a module under a different
887name. This can be accomplished like this:
888
889 import foo
890 bar = foo
891 del foo
892
893but this common idiom gets old quickly. A simple extension of the
894import statement now allows this to be written as follows:
895
896 import foo as bar
897
898There's also a variant for 'from ... import':
899
900 from foo import bar as spam
901
902This also works with packages; e.g. you can write this:
903
904 import test.regrtest as regrtest
905
906Note that 'as' is not a new keyword -- it is recognized only in this
907context (this is only possible because the syntax for the import
908statement doesn't involve expressions).
909
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000910Implemented by Thomas Wouters. Described by PEP 221.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000911
912
913Extended Print Statement
914------------------------
915
916Easily the most controversial new feature, this extension to the print
917statement adds an option to make the output go to a different file
918than the default sys.stdout.
919
920For example, to write an error message to sys.stderr, you can now
921write:
922
923 print >> sys.stderr, "Error: bad dog!"
924
925As a special feature, if the expression used to indicate the file
Fred Drake45888ff2000-09-29 17:09:11 +0000926evaluates to None, the current value of sys.stdout is used. Thus:
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000927
928 print >> None, "Hello world"
929
930is equivalent to
931
932 print "Hello world"
933
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000934Design and implementation by Barry Warsaw. Described by PEP 214.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000935
936
937Optional Collection of Cyclical Garbage
938---------------------------------------
939
940Python is now equipped with a garbage collector that can hunt down
941cyclical references between Python objects. It's no replacement for
942reference counting; in fact, it depends on the reference counts being
943correct, and decides that a set of objects belong to a cycle if all
944their reference counts can be accounted for from their references to
945each other. This devious scheme was first proposed by Eric Tiedemann,
946and brought to implementation by Neil Schemenauer.
947
948There's a module "gc" that lets you control some parameters of the
949garbage collection. There's also an option to the configure script
950that lets you enable or disable the garbage collection. In 2.0b1,
951it's on by default, so that we (hopefully) can collect decent user
952experience with this new feature. There are some questions about its
Fred Drake9f11cf82000-09-29 17:54:40 +0000953performance. If it proves to be too much of a problem, we'll turn it
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000954off by default in the final 2.0 release.
955
956
957Smaller Changes
958---------------
959
960A new function zip() was added. zip(seq1, seq2, ...) is equivalent to
961map(None, seq1, seq2, ...) when the sequences have the same length;
962i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When
963the lists are not all the same length, the shortest list wins:
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000964zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201.
Guido van Rossumf2ffce02000-09-05 04:38:34 +0000965
966sys.version_info is a tuple (major, minor, micro, level, serial).
967
968Dictionaries have an odd new method, setdefault(key, default).
969dict.setdefault(key, default) returns dict[key] if it exists; if not,
970it sets dict[key] to default and returns that value. Thus:
971
972 dict.setdefault(key, []).append(item)
973
974does the same work as this common idiom:
975
976 if not dict.has_key(key):
977 dict[key] = []
978 dict[key].append(item)
979
Jeremy Hylton24c3d602000-09-05 19:36:26 +0000980There are two new variants of SyntaxError that are raised for
981indentation-related errors: IndentationError and TabError.
982
983Changed \x to consume exactly two hex digits; see PEP 223. Added \U
984escape that consumes exactly eight hex digits.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +0000985
986The limits on the size of expressions and file in Python source code
987have been raised from 2**16 to 2**32. Previous versions of Python
988were limited because the maximum argument size the Python VM accepted
989was 2**16. This limited the size of object constructor expressions,
990e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This
991limit was raised thanks to a patch by Charles Waldman that effectively
992fixes the problem. It is now much more likely that you will be
993limited by available memory than by an arbitrary limit in Python.
994
995The interpreter's maximum recursion depth can be modified by Python
996programs using sys.getrecursionlimit and sys.setrecursionlimit. This
997limit is the maximum number of recursive calls that can be made by
998Python code. The limit exists to prevent infinite recursion from
999overflowing the C stack and causing a core dump. The default value is
10001000. The maximum safe value for a particular platform can be found
1001by running Misc/find_recursionlimit.py.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001002
1003New Modules and Packages
1004------------------------
1005
1006atexit - for registering functions to be called when Python exits.
1007
1008imputil - Greg Stein's alternative API for writing custom import
1009hooks.
1010
1011pyexpat - an interface to the Expat XML parser, contributed by Paul
1012Prescod.
1013
1014xml - a new package with XML support code organized (so far) in three
1015subpackages: xml.dom, xml.sax, and xml.parsers. Describing these
1016would fill a volume. There's a special feature whereby a
1017user-installed package named _xmlplus overrides the standard
1018xmlpackage; this is intended to give the XML SIG a hook to distribute
1019backwards-compatible updates to the standard xml package.
1020
1021webbrowser - a platform-independent API to launch a web browser.
1022
1023
Guido van Rossume905e952000-09-05 12:42:46 +00001024Changed Modules
1025---------------
1026
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001027array -- new methods for array objects: count, extend, index, pop, and
1028remove
1029
1030binascii -- new functions b2a_hex and a2b_hex that convert between
1031binary data and its hex representation
1032
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001033calendar -- Many new functions that support features including control
1034over which day of the week is the first day, returning strings instead
1035of printing them. Also new symbolic constants for days of week,
1036e.g. MONDAY, ..., SUNDAY.
1037
1038cgi -- FieldStorage objects have a getvalue method that works like a
1039dictionary's get method and returns the value attribute of the object.
1040
1041ConfigParser -- The parser object has new methods has_option,
1042remove_section, remove_option, set, and write. They allow the module
1043to be used for writing config files as well as reading them.
1044
1045ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now
Guido van Rossume905e952000-09-05 12:42:46 +00001046optionally support the RFC 959 REST command.
1047
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001048gzip -- readline and readlines now accept optional size arguments
Guido van Rossume905e952000-09-05 12:42:46 +00001049
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001050httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See
1051the module doc strings for details.
Guido van Rossum830ca2a2000-09-05 15:34:16 +00001052
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001053locale -- implement getdefaultlocale for Win32 and Macintosh
1054
1055marshal -- no longer dumps core when marshaling deeply nested or
1056recursive data structures
1057
1058os -- new functions isatty, seteuid, setegid, setreuid, setregid
1059
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001060os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3
1061support under Unix.
1062
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001063os/pty -- support for openpty and forkpty
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001064
1065os.path -- fix semantics of os.path.commonprefix
1066
1067smtplib -- support for sending very long messages
1068
1069socket -- new function getfqdn()
1070
1071readline -- new functions to read, write and truncate history files.
1072The readline section of the library reference manual contains an
1073example.
1074
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001075select -- add interface to poll system call
1076
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001077shutil -- new copyfileobj function
1078
1079SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the
1080HTTP server.
1081
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001082Tkinter -- optimization of function flatten
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001083
1084urllib -- scans environment variables for proxy configuration,
Tim Peters8b092332000-09-05 20:15:25 +00001085e.g. http_proxy.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001086
1087whichdb -- recognizes dumbdbm format
Guido van Rossume905e952000-09-05 12:42:46 +00001088
1089
1090Obsolete Modules
1091----------------
1092
1093None. However note that 1.6 made a whole slew of modules obsolete:
1094stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail,
1095poly, zmod, strop, util, whatsound.
1096
1097
1098Changed, New, Obsolete Tools
1099----------------------------
1100
Tim Peters8b092332000-09-05 20:15:25 +00001101None.
Guido van Rossume905e952000-09-05 12:42:46 +00001102
1103
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001104C-level Changes
1105---------------
1106
1107Several cleanup jobs were carried out throughout the source code.
1108
1109All C code was converted to ANSI C; we got rid of all uses of the
1110Py_PROTO() macro, which makes the header files a lot more readable.
1111
1112Most of the portability hacks were moved to a new header file,
1113pyport.h; several other new header files were added and some old
1114header files were removed, in an attempt to create a more rational set
1115of header files. (Few of these ever need to be included explicitly;
1116they are all included by Python.h.)
1117
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001118Trent Mick ensured portability to 64-bit platforms, under both Linux
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001119and Win64, especially for the new Intel Itanium processor. Mick also
1120added large file support for Linux64 and Win64.
Guido van Rossumf2ffce02000-09-05 04:38:34 +00001121
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001122The C APIs to return an object's size have been update to consistently
1123use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In
1124previous versions, the abstract interfaces used PyXXX_Length and the
1125concrete interfaces used PyXXX_Size. The old names,
1126e.g. PyObject_Length, are still available for backwards compatibility
1127at the API level, but are deprecated.
1128
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001129The PyOS_CheckStack function has been implemented on Windows by
1130Fredrik Lundh. It prevents Python from failing with a stack overflow
1131on Windows.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001132
1133The GC changes resulted in creation of two new slots on object,
1134tp_traverse and tp_clear. The augmented assignment changes result in
Guido van Rossum4338a282000-09-06 13:02:08 +00001135the creation of a new slot for each in-place operator.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001136
1137The GC API creates new requirements for container types implemented in
Guido van Rossum4338a282000-09-06 13:02:08 +00001138C extension modules. See Include/objimpl.h for details.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001139
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001140PyErr_Format has been updated to automatically calculate the size of
1141the buffer needed to hold the formatted result string. This change
1142prevents crashes caused by programmer error.
Jeremy Hyltonbdebd542000-09-05 18:28:54 +00001143
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001144New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable.
Guido van Rossume905e952000-09-05 12:42:46 +00001145
Jeremy Hylton24c3d602000-09-05 19:36:26 +00001146PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions
1147that are the same as their non-Ex counterparts except they take an
1148extra flag argument that tells them to close the file when done.
1149
1150XXX There were other API changes that should be fleshed out here.
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001151
Tim Peters8b092332000-09-05 20:15:25 +00001152
1153Windows Changes
1154---------------
1155
1156New popen2/popen3/peopen4 in os module (see Changed Modules above).
1157
1158os.popen is much more usable on Windows 95 and 98. See Microsoft
1159Knowledge Base article Q150956. The Win9x workaround described there
1160is implemented by the new w9xpopen.exe helper in the root of your
1161Python installation. Note that Python uses this internally; it is not
1162a standalone program.
1163
1164Administrator privileges are no longer required to install Python
1165on Windows NT or Windows 2000. If you have administrator privileges,
1166Python's registry info will be written under HKEY_LOCAL_MACHINE.
1167Otherwise the installer backs off to writing Python's registry info
Guido van Rossum4338a282000-09-06 13:02:08 +00001168under HKEY_CURRENT_USER. The latter is sufficient for all "normal"
Tim Peters8b092332000-09-05 20:15:25 +00001169uses of Python, but will prevent some advanced uses from working
1170(for example, running a Python script as an NT service, or possibly
1171from CGI).
1172
1173[This was new in 1.6] The installer no longer runs a separate Tcl/Tk
1174installer; instead, it installs the needed Tcl/Tk files directly in the
1175Python directory. If you already have a Tcl/Tk installation, this
1176wastes some disk space (about 4 Megs) but avoids problems with
1177conflicting Tcl/Tk installations, and makes it much easier for Python
1178to ensure that Tcl/Tk can find all its files.
1179
1180[This was new in 1.6] The Windows installer now installs by default in
1181\Python20\ on the default volume, instead of \Program Files\Python-2.0\.
1182
Guido van Rossumf62ed9c2000-09-26 11:16:10 +00001183
1184Updates to the changes between 1.5.2 and 1.6
1185--------------------------------------------
1186
1187The 1.6 NEWS file can't be changed after the release is done, so here
1188is some late-breaking news:
1189
1190New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(),
1191and changes to getlocale() and setlocale().
1192
1193The new module is now enabled per default.
1194
1195It is not true that the encodings codecs cannot be used for normal
1196strings: the string.encode() (which is also present on 8-bit strings
1197!) allows using them for 8-bit strings too, e.g. to convert files from
1198cp1252 (Windows) to latin-1 or vice-versa.
1199
1200Japanese codecs are available from Tamito KAJIYAMA:
1201http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/
1202
1203
Guido van Rossumab9d6f01998-08-10 22:01:13 +00001204======================================================================