Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 1 | What's New in Python 2.0b2? |
Guido van Rossum | 6100033 | 1997-08-15 04:39:58 +0000 | [diff] [blame] | 2 | =========================== |
| 3 | |
Guido van Rossum | 8ed602b | 2000-09-01 22:34:33 +0000 | [diff] [blame] | 4 | Below is a list of all relevant changes since release 1.6. Older |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 5 | changes are in the file HISTORY. If you are making the jump directly |
| 6 | from Python 1.5.2 to 2.0, make sure to read the section for 1.6 in the |
| 7 | HISTORY file! Many important changes listed there. |
Guido van Rossum | 6100033 | 1997-08-15 04:39:58 +0000 | [diff] [blame] | 8 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 9 | Alternatively, a good overview of the changes between 1.5.2 and 2.0 is |
| 10 | the document "What's New in Python 2.0" by Kuchling and Moshe Zadka: |
| 11 | http://starship.python.net/crew/amk/python/writing/new-python/. |
Guido van Rossum | 1f83cce | 1997-10-06 21:04:35 +0000 | [diff] [blame] | 12 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 13 | --Guido van Rossum (home page: http://www.pythonlabs.com/~guido/) |
Guido van Rossum | 437cfe8 | 1999-04-08 20:17:57 +0000 | [diff] [blame] | 14 | |
| 15 | ====================================================================== |
| 16 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 17 | |
| 18 | What's new in 2.0 beta 2 (since beta 1)? |
| 19 | ======================================== |
| 20 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 21 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 22 | Core language, builtins, and interpreter |
| 23 | |
Tim Peters | 482c021 | 2000-09-26 06:33:09 +0000 | [diff] [blame] | 24 | - Add support for unbounded ints in %d,i,u,x,X,o formats; for example |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 25 | "%d" % 2L**64 == "18446744073709551616". |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 26 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 27 | - Add -h and -V command line options to print the usage message and |
| 28 | Python version number and exit immediately. |
| 29 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 30 | |
| 31 | Standard library and extensions |
| 32 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 33 | - array: reverse() method of array now works. buffer_info() now does |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 34 | argument checking; it still takes no arguments. |
| 35 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 36 | - asyncore/asynchat: Included most recent version from Sam Rushing. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 37 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 38 | - cgi: Accept '&' or ';' as separator characters when parsing form data. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 39 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 40 | - CGIHTTPServer: Now works on Windows (and perhaps even Mac). |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 41 | |
| 42 | - ConfigParser: When reading the file, options spelled in upper case |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 43 | letters are now correctly converted to lowercase. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 44 | |
| 45 | - copy: Copy Unicode objects atomically. |
| 46 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 47 | - cPickle: Fail gracefully when copy_reg can't be imported. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 48 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 49 | - cStringIO: Implemented readlines() method. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 50 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 51 | - dbm: Add set() and setdefault() methods to dbm object. Add constant |
| 52 | `library' to module that names the library used. Better doc strings |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 53 | and argument checking. Uses configure to determine which ndbm.h |
| 54 | file to include; Berkeley DB's nbdm is now an option. |
| 55 | |
| 56 | - distutils: Update to version 0.9.3. |
| 57 | |
| 58 | - dl: Add several dl.RTLD_ constants. |
| 59 | |
| 60 | - fpectl: Now supported on FreeBSD. |
| 61 | |
| 62 | - gc: Add DEBUG_SAVEALL option. When enabled all garbage objects |
| 63 | found by the collector will be saved in gc.garbage. This is useful |
| 64 | for debugging a program that creates reference cycles. |
| 65 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 66 | - httplib: Three changes: Restore support for set_debuglevel feature |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 67 | of HTTP class. Do not close socket on zero-length response. Do not |
| 68 | crash when server sends invalid content-length header. |
| 69 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 70 | - mailbox: Mailbox class conforms better to qmail specifications. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 71 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 72 | - operator: Add contains(), invert(), __invert__() as aliases for |
| 73 | __contains__(), inv(), and __inv__() respectively. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 74 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 75 | - os: Add support for popen2() and popen3() on all platforms where |
| 76 | fork() exists. (popen4() is still in the works.) |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 77 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 78 | - os: (Windows only:) Add startfile() function that acts like double- |
Tim Peters | 482c021 | 2000-09-26 06:33:09 +0000 | [diff] [blame] | 79 | clicking on a file in Explorer (or passing the file name to the |
| 80 | DOS "start" command). |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 81 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 82 | - os.path: (Windows, DOS:) Treat trailing colon correctly in |
Tim Peters | 482c021 | 2000-09-26 06:33:09 +0000 | [diff] [blame] | 83 | os.path.join. os.path.join("a:", "b") yields "a:b". |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 84 | |
| 85 | - pickle: Now raises ValueError when an invalid pickle that contains |
| 86 | a non-string repr where a string repr was expected. This behavior |
| 87 | matches cPickle. |
| 88 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 89 | - posixfile: Remove broken __del__() method. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 90 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 91 | - py_compile: support CR+LF line terminators in source file. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 92 | |
| 93 | - readline: Does not immediately exit when ^C is hit when readline and |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 94 | threads are configured. Adds defintion of rl_library_version. (The |
| 95 | latter addition requires GNU readline 2.2 or later.) |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 96 | |
| 97 | - rfc822: Domain literals returned by AddrlistClass method |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 98 | getdomainliteral() are now properly wrapped in brackets. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 99 | |
| 100 | - site: sys.setdefaultencoding() should only be called in case the |
Tim Peters | 482c021 | 2000-09-26 06:33:09 +0000 | [diff] [blame] | 101 | standard default encoding ("ascii") is changed. This saves quite a |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 102 | few cycles during startup since the first call to |
| 103 | setdefaultencoding() will initialize the codec registry and the |
| 104 | encodings package. |
| 105 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 106 | - socket: Support for size hint in readlines() method of object returned |
| 107 | by makefile(). |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 108 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 109 | - sre: Added experimental expand() method to match objects. Does not |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 110 | user buffer interface on Unicode strings. Does not hang if group id |
| 111 | is followed by whitespace. |
| 112 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 113 | - StringIO: size hint in readlines() is now supported as documented. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 114 | |
| 115 | - struct: Check ranges for bytes and shorts. |
| 116 | |
| 117 | - urllib: Improved handling of win32 proxy settings. Fixed quote and |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 118 | quote_plus functions so that the always encode a comma. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 119 | |
| 120 | - Tkinter: Image objects are now guaranteed to have unique ids. Set |
| 121 | event.delta to zero if Tk version doesn't support mousewheel. |
| 122 | Removed some debugging prints. |
| 123 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 124 | - UserList: now implements __contains__(). |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 125 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 126 | - webbrower: On Windows, use os.startfile() instead of os.popen(), |
| 127 | which works around a bug in Norton AntiVirus 2000 that leads directly |
| 128 | to a Blue Screen freeze. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 129 | |
| 130 | - xml: New version detection code allows PyXML to override standard |
| 131 | XML package if PyXML version is greater than 0.6.1. |
| 132 | |
| 133 | - xml.dom: XXX |
| 134 | |
| 135 | - xml.sax: XXX |
| 136 | |
| 137 | - XXX pyexpat: XXX |
| 138 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 139 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 140 | C API |
| 141 | |
| 142 | - Add three new convenience functions for module initialization -- |
| 143 | PyModule_AddObject(), PyModule_AddIntConstant(), and |
| 144 | PyModule_AddStringConstant(). |
| 145 | |
| 146 | - Cleaned up definition of NULL in C source code; all defintions were |
| 147 | removed and add #error to Python.h if NULL isn't defined after |
| 148 | #include of stdio.h. |
| 149 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 150 | - Py_PROTO() macros that were removed in 2.0b1 have been restored for |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 151 | backwards compatibility (at the source level) with old extensions. |
| 152 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 153 | - A wrapper API was added for signal() and sigaction(). Instead of |
| 154 | either function, always use PyOS_getsig() to get a signal handler |
| 155 | and PyOS_setsig() to set one. A new convenience typedef |
| 156 | PyOS_sighandler_t is defined for the type of signal handlers. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 157 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 158 | - Add PyString_AsStringAndSize() function that provides access to the |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 159 | internal data buffer and size of a string object -- or the default |
| 160 | encoded version of a Unicode object. |
| 161 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 162 | - The standard header <limits.h> is now included by Python.h (if it |
| 163 | exists). |
| 164 | |
| 165 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 166 | Internals |
| 167 | |
| 168 | - On Unix, fix code for finding Python installation directory so that |
| 169 | it works when argv[0] is a relative path. |
| 170 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 171 | - Added a true unicode_internal_encode() function and fixed the |
| 172 | unicode_internal_decode function() to support Unicode objects directly |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 173 | rather than by generating a copy of the object. |
| 174 | |
Tim Peters | 482c021 | 2000-09-26 06:33:09 +0000 | [diff] [blame] | 175 | - Several of the internal Unicode tables are much smaller now, and |
| 176 | the source code should be much friendlier to weaker compilers. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 177 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 178 | |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 179 | Build and platform-specific issues |
| 180 | |
| 181 | - Better support of GNU Pth via --with-pth configure option. |
| 182 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 183 | - Fix linker problems on Reliant UNIX. |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 184 | |
| 185 | - Changes for the benefit of SunOS 4.1.4 (really!). mmapmodule.c: |
| 186 | Don't define MS_SYNC to be zero when it is undefined. Added missing |
| 187 | prototypes in posixmodule.c. |
| 188 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 189 | - Improved support for HP-UX build -- threads should now be correctly |
| 190 | configured (on HP-UX 10.20 and 11.00). |
Jeremy Hylton | 1b61859 | 2000-09-26 05:32:36 +0000 | [diff] [blame] | 191 | |
| 192 | |
| 193 | What's new in 2.0 beta 1? |
| 194 | ========================= |
| 195 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 196 | Source Incompatibilities |
| 197 | ------------------------ |
| 198 | |
| 199 | None. Note that 1.6 introduced several incompatibilities with 1.5.2, |
| 200 | such as single-argument append(), connect() and bind(), and changes to |
| 201 | str(long) and repr(float). |
| 202 | |
| 203 | |
| 204 | Binary Incompatibilities |
| 205 | ------------------------ |
| 206 | |
| 207 | - Third party extensions built for Python 1.5.x or 1.6 cannot be used |
| 208 | with Python 2.0; these extensions will have to be rebuilt for Python |
| 209 | 2.0. |
| 210 | |
| 211 | - On Windows, attempting to import a third party extension built for |
| 212 | Python 1.5.x or 1.6 results in an immediate crash; there's not much we |
| 213 | can do about this. Check your PYTHONPATH environment variable! |
| 214 | |
| 215 | - Python bytecode files (*.pyc and *.pyo) are not compatible between |
| 216 | releases. |
| 217 | |
| 218 | |
| 219 | Overview of Changes Since 1.6 |
| 220 | ----------------------------- |
| 221 | |
| 222 | There are many new modules (including brand new XML support through |
| 223 | the xml package, and i18n support through the gettext module); a list |
| 224 | of all new modules is included below. Lots of bugs have been fixed. |
| 225 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 226 | The process for making major new changes to the language has changed |
| 227 | since Python 1.6. Enhancements must now be documented by a Python |
| 228 | Enhancement Proposal (PEP) before they can be accepted. |
| 229 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 230 | There are several important syntax enhancements, described in more |
| 231 | detail below: |
| 232 | |
| 233 | - Augmented assignment, e.g. x += 1 |
| 234 | |
| 235 | - List comprehensions, e.g. [x**2 for x in range(10)] |
| 236 | |
| 237 | - Extended import statement, e.g. import Module as Name |
| 238 | |
| 239 | - Extended print statement, e.g. print >> file, "Hello" |
| 240 | |
| 241 | Other important changes: |
| 242 | |
| 243 | - Optional collection of cyclical garbage |
| 244 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 245 | Python Enhancement Proposal (PEP) |
| 246 | --------------------------------- |
| 247 | |
| 248 | PEP stands for Python Enhancement Proposal. A PEP is a design |
| 249 | document providing information to the Python community, or describing |
| 250 | a new feature for Python. The PEP should provide a concise technical |
| 251 | specification of the feature and a rationale for the feature. |
| 252 | |
| 253 | We intend PEPs to be the primary mechanisms for proposing new |
| 254 | features, for collecting community input on an issue, and for |
| 255 | documenting the design decisions that have gone into Python. The PEP |
| 256 | author is responsible for building consensus within the community and |
| 257 | documenting dissenting opinions. |
| 258 | |
| 259 | The PEPs are available at http://python.sourceforge.net/peps/. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 260 | |
| 261 | Augmented Assignment |
| 262 | -------------------- |
| 263 | |
| 264 | This must have been the most-requested feature of the past years! |
| 265 | Eleven new assignment operators were added: |
| 266 | |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 267 | += -= *= /= %= **= <<= >>= &= ^= |= |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 268 | |
| 269 | For example, |
| 270 | |
| 271 | A += B |
| 272 | |
| 273 | is similar to |
| 274 | |
| 275 | A = A + B |
| 276 | |
| 277 | except that A is evaluated only once (relevant when A is something |
| 278 | like dict[index].attr). |
| 279 | |
| 280 | However, if A is a mutable object, A may be modified in place. Thus, |
| 281 | if A is a number or a string, A += B has the same effect as A = A+B |
| 282 | (except A is only evaluated once); but if a is a list, A += B has the |
| 283 | same effect as A.extend(B)! |
| 284 | |
| 285 | Classes and built-in object types can override the new operators in |
| 286 | order to implement the in-place behavior; the not-in-place behavior is |
| 287 | used automatically as a fallback when an object doesn't implement the |
| 288 | in-place behavior. For classes, the method name is derived from the |
| 289 | method name for the corresponding not-in-place operator by inserting |
| 290 | an 'i' in front of the name, e.g. __iadd__ implements in-place |
| 291 | __add__. |
| 292 | |
| 293 | Augmented assignment was implemented by Thomas Wouters. |
| 294 | |
| 295 | |
| 296 | List Comprehensions |
| 297 | ------------------- |
| 298 | |
| 299 | This is a flexible new notation for lists whose elements are computed |
| 300 | from another list (or lists). The simplest form is: |
| 301 | |
| 302 | [<expression> for <variable> in <sequence>] |
| 303 | |
Guido van Rossum | 56db095 | 2000-09-06 23:34:25 +0000 | [diff] [blame] | 304 | For example, [i**2 for i in range(4)] yields the list [0, 1, 4, 9]. |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 305 | This is more efficient than a for loop with a list.append() call. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 306 | |
| 307 | You can also add a condition: |
| 308 | |
| 309 | [<expression> for <variable> in <sequence> if <condition>] |
| 310 | |
| 311 | For example, [w for w in words if w == w.lower()] would yield the list |
| 312 | of words that contain no uppercase characters. This is more efficient |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 313 | than a for loop with an if statement and a list.append() call. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 314 | |
| 315 | You can also have nested for loops and more than one 'if' clause. For |
| 316 | example, here's a function that flattens a sequence of sequences:: |
| 317 | |
| 318 | def flatten(seq): |
| 319 | return [x for subseq in seq for x in subseq] |
| 320 | |
| 321 | flatten([[0], [1,2,3], [4,5], [6,7,8,9], []]) |
| 322 | |
| 323 | This prints |
| 324 | |
| 325 | [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] |
| 326 | |
| 327 | List comprehensions originated as a patch set from Greg Ewing; Skip |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 328 | Montanaro and Thomas Wouters also contributed. Described by PEP 202. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 329 | |
| 330 | |
| 331 | Extended Import Statement |
| 332 | ------------------------- |
| 333 | |
| 334 | Many people have asked for a way to import a module under a different |
| 335 | name. This can be accomplished like this: |
| 336 | |
| 337 | import foo |
| 338 | bar = foo |
| 339 | del foo |
| 340 | |
| 341 | but this common idiom gets old quickly. A simple extension of the |
| 342 | import statement now allows this to be written as follows: |
| 343 | |
| 344 | import foo as bar |
| 345 | |
| 346 | There's also a variant for 'from ... import': |
| 347 | |
| 348 | from foo import bar as spam |
| 349 | |
| 350 | This also works with packages; e.g. you can write this: |
| 351 | |
| 352 | import test.regrtest as regrtest |
| 353 | |
| 354 | Note that 'as' is not a new keyword -- it is recognized only in this |
| 355 | context (this is only possible because the syntax for the import |
| 356 | statement doesn't involve expressions). |
| 357 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 358 | Implemented by Thomas Wouters. Described by PEP 221. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 359 | |
| 360 | |
| 361 | Extended Print Statement |
| 362 | ------------------------ |
| 363 | |
| 364 | Easily the most controversial new feature, this extension to the print |
| 365 | statement adds an option to make the output go to a different file |
| 366 | than the default sys.stdout. |
| 367 | |
| 368 | For example, to write an error message to sys.stderr, you can now |
| 369 | write: |
| 370 | |
| 371 | print >> sys.stderr, "Error: bad dog!" |
| 372 | |
| 373 | As a special feature, if the expression used to indicate the file |
| 374 | evaluates to None, the current value of sys.stdout used. Thus: |
| 375 | |
| 376 | print >> None, "Hello world" |
| 377 | |
| 378 | is equivalent to |
| 379 | |
| 380 | print "Hello world" |
| 381 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 382 | Design and implementation by Barry Warsaw. Described by PEP 214. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 383 | |
| 384 | |
| 385 | Optional Collection of Cyclical Garbage |
| 386 | --------------------------------------- |
| 387 | |
| 388 | Python is now equipped with a garbage collector that can hunt down |
| 389 | cyclical references between Python objects. It's no replacement for |
| 390 | reference counting; in fact, it depends on the reference counts being |
| 391 | correct, and decides that a set of objects belong to a cycle if all |
| 392 | their reference counts can be accounted for from their references to |
| 393 | each other. This devious scheme was first proposed by Eric Tiedemann, |
| 394 | and brought to implementation by Neil Schemenauer. |
| 395 | |
| 396 | There's a module "gc" that lets you control some parameters of the |
| 397 | garbage collection. There's also an option to the configure script |
| 398 | that lets you enable or disable the garbage collection. In 2.0b1, |
| 399 | it's on by default, so that we (hopefully) can collect decent user |
| 400 | experience with this new feature. There are some questions about its |
| 401 | performance. if it proves to be too much of a problem, we'll turn it |
| 402 | off by default in the final 2.0 release. |
| 403 | |
| 404 | |
| 405 | Smaller Changes |
| 406 | --------------- |
| 407 | |
| 408 | A new function zip() was added. zip(seq1, seq2, ...) is equivalent to |
| 409 | map(None, seq1, seq2, ...) when the sequences have the same length; |
| 410 | i.e. zip([1,2,3], [10,20,30]) returns [(1,10), (2,20), (3,30)]. When |
| 411 | the lists are not all the same length, the shortest list wins: |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 412 | zip([1,2,3], [10,20]) returns [(1,10), (2,20)]. See PEP 201. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 413 | |
| 414 | sys.version_info is a tuple (major, minor, micro, level, serial). |
| 415 | |
| 416 | Dictionaries have an odd new method, setdefault(key, default). |
| 417 | dict.setdefault(key, default) returns dict[key] if it exists; if not, |
| 418 | it sets dict[key] to default and returns that value. Thus: |
| 419 | |
| 420 | dict.setdefault(key, []).append(item) |
| 421 | |
| 422 | does the same work as this common idiom: |
| 423 | |
| 424 | if not dict.has_key(key): |
| 425 | dict[key] = [] |
| 426 | dict[key].append(item) |
| 427 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 428 | There are two new variants of SyntaxError that are raised for |
| 429 | indentation-related errors: IndentationError and TabError. |
| 430 | |
| 431 | Changed \x to consume exactly two hex digits; see PEP 223. Added \U |
| 432 | escape that consumes exactly eight hex digits. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 433 | |
| 434 | The limits on the size of expressions and file in Python source code |
| 435 | have been raised from 2**16 to 2**32. Previous versions of Python |
| 436 | were limited because the maximum argument size the Python VM accepted |
| 437 | was 2**16. This limited the size of object constructor expressions, |
| 438 | e.g. [1,2,3] or {'a':1, 'b':2}, and the size of source files. This |
| 439 | limit was raised thanks to a patch by Charles Waldman that effectively |
| 440 | fixes the problem. It is now much more likely that you will be |
| 441 | limited by available memory than by an arbitrary limit in Python. |
| 442 | |
| 443 | The interpreter's maximum recursion depth can be modified by Python |
| 444 | programs using sys.getrecursionlimit and sys.setrecursionlimit. This |
| 445 | limit is the maximum number of recursive calls that can be made by |
| 446 | Python code. The limit exists to prevent infinite recursion from |
| 447 | overflowing the C stack and causing a core dump. The default value is |
| 448 | 1000. The maximum safe value for a particular platform can be found |
| 449 | by running Misc/find_recursionlimit.py. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 450 | |
| 451 | New Modules and Packages |
| 452 | ------------------------ |
| 453 | |
| 454 | atexit - for registering functions to be called when Python exits. |
| 455 | |
| 456 | imputil - Greg Stein's alternative API for writing custom import |
| 457 | hooks. |
| 458 | |
| 459 | pyexpat - an interface to the Expat XML parser, contributed by Paul |
| 460 | Prescod. |
| 461 | |
| 462 | xml - a new package with XML support code organized (so far) in three |
| 463 | subpackages: xml.dom, xml.sax, and xml.parsers. Describing these |
| 464 | would fill a volume. There's a special feature whereby a |
| 465 | user-installed package named _xmlplus overrides the standard |
| 466 | xmlpackage; this is intended to give the XML SIG a hook to distribute |
| 467 | backwards-compatible updates to the standard xml package. |
| 468 | |
| 469 | webbrowser - a platform-independent API to launch a web browser. |
| 470 | |
| 471 | |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 472 | Changed Modules |
| 473 | --------------- |
| 474 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 475 | array -- new methods for array objects: count, extend, index, pop, and |
| 476 | remove |
| 477 | |
| 478 | binascii -- new functions b2a_hex and a2b_hex that convert between |
| 479 | binary data and its hex representation |
| 480 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 481 | calendar -- Many new functions that support features including control |
| 482 | over which day of the week is the first day, returning strings instead |
| 483 | of printing them. Also new symbolic constants for days of week, |
| 484 | e.g. MONDAY, ..., SUNDAY. |
| 485 | |
| 486 | cgi -- FieldStorage objects have a getvalue method that works like a |
| 487 | dictionary's get method and returns the value attribute of the object. |
| 488 | |
| 489 | ConfigParser -- The parser object has new methods has_option, |
| 490 | remove_section, remove_option, set, and write. They allow the module |
| 491 | to be used for writing config files as well as reading them. |
| 492 | |
| 493 | ftplib -- ntransfercmd(), transfercmd(), and retrbinary() all now |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 494 | optionally support the RFC 959 REST command. |
| 495 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 496 | gzip -- readline and readlines now accept optional size arguments |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 497 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 498 | httplib -- New interfaces and support for HTTP/1.1 by Greg Stein. See |
| 499 | the module doc strings for details. |
Guido van Rossum | 830ca2a | 2000-09-05 15:34:16 +0000 | [diff] [blame] | 500 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 501 | locale -- implement getdefaultlocale for Win32 and Macintosh |
| 502 | |
| 503 | marshal -- no longer dumps core when marshaling deeply nested or |
| 504 | recursive data structures |
| 505 | |
| 506 | os -- new functions isatty, seteuid, setegid, setreuid, setregid |
| 507 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 508 | os/popen2 -- popen2/popen3/popen4 support under Windows. popen2/popen3 |
| 509 | support under Unix. |
| 510 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 511 | os/pty -- support for openpty and forkpty |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 512 | |
| 513 | os.path -- fix semantics of os.path.commonprefix |
| 514 | |
| 515 | smtplib -- support for sending very long messages |
| 516 | |
| 517 | socket -- new function getfqdn() |
| 518 | |
| 519 | readline -- new functions to read, write and truncate history files. |
| 520 | The readline section of the library reference manual contains an |
| 521 | example. |
| 522 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 523 | select -- add interface to poll system call |
| 524 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 525 | shutil -- new copyfileobj function |
| 526 | |
| 527 | SimpleHTTPServer, CGIHTTPServer -- Fix problems with buffering in the |
| 528 | HTTP server. |
| 529 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 530 | Tkinter -- optimization of function flatten |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 531 | |
| 532 | urllib -- scans environment variables for proxy configuration, |
Tim Peters | 8b09233 | 2000-09-05 20:15:25 +0000 | [diff] [blame] | 533 | e.g. http_proxy. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 534 | |
| 535 | whichdb -- recognizes dumbdbm format |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 536 | |
| 537 | |
| 538 | Obsolete Modules |
| 539 | ---------------- |
| 540 | |
| 541 | None. However note that 1.6 made a whole slew of modules obsolete: |
| 542 | stdwin, soundex, cml, cmpcache, dircache, dump, find, grep, packmail, |
| 543 | poly, zmod, strop, util, whatsound. |
| 544 | |
| 545 | |
| 546 | Changed, New, Obsolete Tools |
| 547 | ---------------------------- |
| 548 | |
Tim Peters | 8b09233 | 2000-09-05 20:15:25 +0000 | [diff] [blame] | 549 | None. |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 550 | |
| 551 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 552 | C-level Changes |
| 553 | --------------- |
| 554 | |
| 555 | Several cleanup jobs were carried out throughout the source code. |
| 556 | |
| 557 | All C code was converted to ANSI C; we got rid of all uses of the |
| 558 | Py_PROTO() macro, which makes the header files a lot more readable. |
| 559 | |
| 560 | Most of the portability hacks were moved to a new header file, |
| 561 | pyport.h; several other new header files were added and some old |
| 562 | header files were removed, in an attempt to create a more rational set |
| 563 | of header files. (Few of these ever need to be included explicitly; |
| 564 | they are all included by Python.h.) |
| 565 | |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 566 | Trent Mick ensured portability to 64-bit platforms, under both Linux |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 567 | and Win64, especially for the new Intel Itanium processor. Mick also |
| 568 | added large file support for Linux64 and Win64. |
Guido van Rossum | f2ffce0 | 2000-09-05 04:38:34 +0000 | [diff] [blame] | 569 | |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 570 | The C APIs to return an object's size have been update to consistently |
| 571 | use the form PyXXX_Size, e.g. PySequence_Size and PyDict_Size. In |
| 572 | previous versions, the abstract interfaces used PyXXX_Length and the |
| 573 | concrete interfaces used PyXXX_Size. The old names, |
| 574 | e.g. PyObject_Length, are still available for backwards compatibility |
| 575 | at the API level, but are deprecated. |
| 576 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 577 | The PyOS_CheckStack function has been implemented on Windows by |
| 578 | Fredrik Lundh. It prevents Python from failing with a stack overflow |
| 579 | on Windows. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 580 | |
| 581 | The GC changes resulted in creation of two new slots on object, |
| 582 | tp_traverse and tp_clear. The augmented assignment changes result in |
Guido van Rossum | 4338a28 | 2000-09-06 13:02:08 +0000 | [diff] [blame] | 583 | the creation of a new slot for each in-place operator. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 584 | |
| 585 | The GC API creates new requirements for container types implemented in |
Guido van Rossum | 4338a28 | 2000-09-06 13:02:08 +0000 | [diff] [blame] | 586 | C extension modules. See Include/objimpl.h for details. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 587 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 588 | PyErr_Format has been updated to automatically calculate the size of |
| 589 | the buffer needed to hold the formatted result string. This change |
| 590 | prevents crashes caused by programmer error. |
Jeremy Hylton | bdebd54 | 2000-09-05 18:28:54 +0000 | [diff] [blame] | 591 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 592 | New C API calls: PyObject_AsFileDescriptor, PyErr_WriteUnraisable. |
Guido van Rossum | e905e95 | 2000-09-05 12:42:46 +0000 | [diff] [blame] | 593 | |
Jeremy Hylton | 24c3d60 | 2000-09-05 19:36:26 +0000 | [diff] [blame] | 594 | PyRun_AnyFileEx, PyRun_SimpleFileEx, PyRun_FileEx -- New functions |
| 595 | that are the same as their non-Ex counterparts except they take an |
| 596 | extra flag argument that tells them to close the file when done. |
| 597 | |
| 598 | XXX There were other API changes that should be fleshed out here. |
Guido van Rossum | ab9d6f0 | 1998-08-10 22:01:13 +0000 | [diff] [blame] | 599 | |
Tim Peters | 8b09233 | 2000-09-05 20:15:25 +0000 | [diff] [blame] | 600 | |
| 601 | Windows Changes |
| 602 | --------------- |
| 603 | |
| 604 | New popen2/popen3/peopen4 in os module (see Changed Modules above). |
| 605 | |
| 606 | os.popen is much more usable on Windows 95 and 98. See Microsoft |
| 607 | Knowledge Base article Q150956. The Win9x workaround described there |
| 608 | is implemented by the new w9xpopen.exe helper in the root of your |
| 609 | Python installation. Note that Python uses this internally; it is not |
| 610 | a standalone program. |
| 611 | |
| 612 | Administrator privileges are no longer required to install Python |
| 613 | on Windows NT or Windows 2000. If you have administrator privileges, |
| 614 | Python's registry info will be written under HKEY_LOCAL_MACHINE. |
| 615 | Otherwise the installer backs off to writing Python's registry info |
Guido van Rossum | 4338a28 | 2000-09-06 13:02:08 +0000 | [diff] [blame] | 616 | under HKEY_CURRENT_USER. The latter is sufficient for all "normal" |
Tim Peters | 8b09233 | 2000-09-05 20:15:25 +0000 | [diff] [blame] | 617 | uses of Python, but will prevent some advanced uses from working |
| 618 | (for example, running a Python script as an NT service, or possibly |
| 619 | from CGI). |
| 620 | |
| 621 | [This was new in 1.6] The installer no longer runs a separate Tcl/Tk |
| 622 | installer; instead, it installs the needed Tcl/Tk files directly in the |
| 623 | Python directory. If you already have a Tcl/Tk installation, this |
| 624 | wastes some disk space (about 4 Megs) but avoids problems with |
| 625 | conflicting Tcl/Tk installations, and makes it much easier for Python |
| 626 | to ensure that Tcl/Tk can find all its files. |
| 627 | |
| 628 | [This was new in 1.6] The Windows installer now installs by default in |
| 629 | \Python20\ on the default volume, instead of \Program Files\Python-2.0\. |
| 630 | |
Guido van Rossum | f62ed9c | 2000-09-26 11:16:10 +0000 | [diff] [blame^] | 631 | |
| 632 | Updates to the changes between 1.5.2 and 1.6 |
| 633 | -------------------------------------------- |
| 634 | |
| 635 | The 1.6 NEWS file can't be changed after the release is done, so here |
| 636 | is some late-breaking news: |
| 637 | |
| 638 | New APIs in locale.py: normalize(), getdefaultlocale(), resetlocale(), |
| 639 | and changes to getlocale() and setlocale(). |
| 640 | |
| 641 | The new module is now enabled per default. |
| 642 | |
| 643 | It is not true that the encodings codecs cannot be used for normal |
| 644 | strings: the string.encode() (which is also present on 8-bit strings |
| 645 | !) allows using them for 8-bit strings too, e.g. to convert files from |
| 646 | cp1252 (Windows) to latin-1 or vice-versa. |
| 647 | |
| 648 | Japanese codecs are available from Tamito KAJIYAMA: |
| 649 | http://pseudo.grad.sccs.chukyo-u.ac.jp/~kajiyama/python/ |
| 650 | |
| 651 | |
Guido van Rossum | ab9d6f0 | 1998-08-10 22:01:13 +0000 | [diff] [blame] | 652 | ====================================================================== |