cpython/Doc/howto/cporting.rst

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Devil merge! Merged revisions 66561,66564,66580,66610,66614,66618,66624-66625,66628-66629,66643,66645,66660-66665 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r66561 | benjamin.peterson | 2008-09-22 17:13:29 -0500 (Mon, 22 Sep 2008) | 1 line clean up docs for platform's linux_distribution and dist functions ........ r66564 | benjamin.peterson | 2008-09-23 08:32:46 -0500 (Tue, 23 Sep 2008) | 1 line mention how to override boolean evaluation ........ r66580 | georg.brandl | 2008-09-24 04:47:55 -0500 (Wed, 24 Sep 2008) | 2 lines Indentation normalization. ........ r66610 | andrew.kuchling | 2008-09-24 12:27:55 -0500 (Wed, 24 Sep 2008) | 1 line Improve wording ........ r66614 | benjamin.peterson | 2008-09-24 17:11:59 -0500 (Wed, 24 Sep 2008) | 4 lines #3950 fix missing scale factors in turtle.py reviewers: Georg, Benjamin ........ r66618 | benjamin.peterson | 2008-09-25 15:35:45 -0500 (Thu, 25 Sep 2008) | 1 line add a NEWs entry for r66614 ........ r66624 | raymond.hettinger | 2008-09-25 18:31:52 -0500 (Thu, 25 Sep 2008) | 1 line Fix namedtuple bug reported by Glenn Linderman. Template did not form correctly if the field names were input in Unicode. ........ r66625 | benjamin.peterson | 2008-09-25 21:58:36 -0500 (Thu, 25 Sep 2008) | 1 line add the beginnings of a C-API 2 -> 3 porting guide ........ r66628 | benjamin.peterson | 2008-09-26 15:52:06 -0500 (Fri, 26 Sep 2008) | 1 line add an 'other options' section ........ r66629 | georg.brandl | 2008-09-26 16:15:21 -0500 (Fri, 26 Sep 2008) | 2 lines typos. ........ r66643 | andrew.kuchling | 2008-09-27 09:12:33 -0500 (Sat, 27 Sep 2008) | 1 line Add a last bunch of items ........ r66645 | benjamin.peterson | 2008-09-27 11:23:55 -0500 (Sat, 27 Sep 2008) | 1 line 2to3's api should be considered unstable ........ r66660 | andrew.kuchling | 2008-09-27 17:54:08 -0500 (Sat, 27 Sep 2008) | 1 line #3510: future-proof text ........ r66661 | benjamin.peterson | 2008-09-27 18:28:43 -0500 (Sat, 27 Sep 2008) | 1 line clarify a few things ........ r66662 | andrew.kuchling | 2008-09-27 19:15:27 -0500 (Sat, 27 Sep 2008) | 1 line #1579477: mention necessity to flush output before exec'ing ........ r66663 | andrew.kuchling | 2008-09-27 20:08:47 -0500 (Sat, 27 Sep 2008) | 1 line #1415508: Document two functions ........ r66664 | benjamin.peterson | 2008-09-27 20:51:36 -0500 (Sat, 27 Sep 2008) | 1 line better grammar ........ r66665 | benjamin.peterson | 2008-09-27 20:53:29 -0500 (Sat, 27 Sep 2008) | 1 line note the 2to3 -d could be useful for other refactoring ........
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.. highlightlang:: c
.. _cporting-howto:
Devil merge! Merged revisions 66561,66564,66580,66610,66614,66618,66624-66625,66628-66629,66643,66645,66660-66665 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r66561 | benjamin.peterson | 2008-09-22 17:13:29 -0500 (Mon, 22 Sep 2008) | 1 line clean up docs for platform's linux_distribution and dist functions ........ r66564 | benjamin.peterson | 2008-09-23 08:32:46 -0500 (Tue, 23 Sep 2008) | 1 line mention how to override boolean evaluation ........ r66580 | georg.brandl | 2008-09-24 04:47:55 -0500 (Wed, 24 Sep 2008) | 2 lines Indentation normalization. ........ r66610 | andrew.kuchling | 2008-09-24 12:27:55 -0500 (Wed, 24 Sep 2008) | 1 line Improve wording ........ r66614 | benjamin.peterson | 2008-09-24 17:11:59 -0500 (Wed, 24 Sep 2008) | 4 lines #3950 fix missing scale factors in turtle.py reviewers: Georg, Benjamin ........ r66618 | benjamin.peterson | 2008-09-25 15:35:45 -0500 (Thu, 25 Sep 2008) | 1 line add a NEWs entry for r66614 ........ r66624 | raymond.hettinger | 2008-09-25 18:31:52 -0500 (Thu, 25 Sep 2008) | 1 line Fix namedtuple bug reported by Glenn Linderman. Template did not form correctly if the field names were input in Unicode. ........ r66625 | benjamin.peterson | 2008-09-25 21:58:36 -0500 (Thu, 25 Sep 2008) | 1 line add the beginnings of a C-API 2 -> 3 porting guide ........ r66628 | benjamin.peterson | 2008-09-26 15:52:06 -0500 (Fri, 26 Sep 2008) | 1 line add an 'other options' section ........ r66629 | georg.brandl | 2008-09-26 16:15:21 -0500 (Fri, 26 Sep 2008) | 2 lines typos. ........ r66643 | andrew.kuchling | 2008-09-27 09:12:33 -0500 (Sat, 27 Sep 2008) | 1 line Add a last bunch of items ........ r66645 | benjamin.peterson | 2008-09-27 11:23:55 -0500 (Sat, 27 Sep 2008) | 1 line 2to3's api should be considered unstable ........ r66660 | andrew.kuchling | 2008-09-27 17:54:08 -0500 (Sat, 27 Sep 2008) | 1 line #3510: future-proof text ........ r66661 | benjamin.peterson | 2008-09-27 18:28:43 -0500 (Sat, 27 Sep 2008) | 1 line clarify a few things ........ r66662 | andrew.kuchling | 2008-09-27 19:15:27 -0500 (Sat, 27 Sep 2008) | 1 line #1579477: mention necessity to flush output before exec'ing ........ r66663 | andrew.kuchling | 2008-09-27 20:08:47 -0500 (Sat, 27 Sep 2008) | 1 line #1415508: Document two functions ........ r66664 | benjamin.peterson | 2008-09-27 20:51:36 -0500 (Sat, 27 Sep 2008) | 1 line better grammar ........ r66665 | benjamin.peterson | 2008-09-27 20:53:29 -0500 (Sat, 27 Sep 2008) | 1 line note the 2to3 -d could be useful for other refactoring ........
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********************************
Porting Extension Modules to 3.0
********************************
:author: Benjamin Peterson
.. topic:: Abstract
Although changing the C-API was not one of Python 3.0's objectives, the many
Python level changes made leaving 2.x's API intact impossible. In fact, some
changes such as :func:`int` and :func:`long` unification are more obvious on
the C level. This document endeavors to document incompatibilities and how
they can be worked around.
Conditional compilation
=======================
The easiest way to compile only some code for 3.0 is to check if
:cmacro:`PY_MAJOR_VERSION` is greater than or equal to 3. ::
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#endif
API functions that are not present can be aliased to their equivalents within
conditional blocks.
Changes to Object APIs
======================
Python 3.0 merged together some types with similar functions while cleanly
separating others.
str/unicode Unification
-----------------------
Python 3.0's :func:`str` (``PyString_*`` functions in C) type is equivalent to
2.x's :func:`unicode` (``PyUnicode_*``). The old 8-bit string type has become
:func:`bytes`. Python 2.6 and later provide a compatibility header,
:file:`bytesobject.h`, mapping ``PyBytes`` names to ``PyString`` ones. For best
compatibility with 3.0, :ctype:`PyUnicode` should be used for textual data and
:ctype:`PyBytes` for binary data. It's also important to remember that
:ctype:`PyBytes` and :ctype:`PyUnicode` in 3.0 are not interchangeable like
:ctype:`PyString` and :ctype:`PyString` are in 2.x. The following example shows
best practices with regards to :ctype:`PyUnicode`, :ctype:`PyString`, and
:ctype:`PyBytes`. ::
#include "stdlib.h"
#include "Python.h"
#include "bytesobject.h"
/* text example */
static PyObject *
say_hello(PyObject *self, PyObject *args) {
PyObject *name, *result;
if (!PyArg_ParseTuple(args, "U:say_hello", &name))
return NULL;
result = PyUnicode_FromFormat("Hello, %S!", name);
return result;
}
/* just a forward */
static char * do_encode(PyObject *);
/* bytes example */
static PyObject *
encode_object(PyObject *self, PyObject *args) {
char *encoded;
PyObject *result, *myobj;
if (!PyArg_ParseTuple(args, "O:encode_object", &myobj))
return NULL;
encoded = do_encode(myobj);
if (encoded == NULL)
return NULL;
result = PyBytes_FromString(encoded);
free(encoded);
return result;
}
long/int Unification
--------------------
In Python 3.0, there is only one integer type. It is called :func:`int` on the
Python level, but actually corresponds to 2.x's :func:`long` type. In the
C-API, ``PyInt_*`` functions are replaced by their ``PyLong_*`` neighbors. The
best course of action here is using the ``PyInt_*`` functions aliased to
Merged revisions 70712,70714,70764-70765,70769-70771,70773,70776-70777,70788-70789,70824,70828,70832,70836,70842,70851,70855,70857,70866-70872,70883,70885,70893-70894,70896-70897,70903,70905-70907,70915,70927,70933,70951,70960,70962-70964,70998,71001,71006,71008,71010-71011,71019,71037,71056,71094,71101-71103,71106,71119,71123,71149-71150,71203,71212,71214-71217,71221,71240 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r70712 | benjamin.peterson | 2009-03-30 10:15:38 -0500 (Mon, 30 Mar 2009) | 1 line don't rely on the order dict repr #5605 ........ r70714 | brett.cannon | 2009-03-30 10:20:53 -0500 (Mon, 30 Mar 2009) | 1 line Add an entry to developers.txt. ........ r70764 | martin.v.loewis | 2009-03-30 17:06:33 -0500 (Mon, 30 Mar 2009) | 2 lines Add several VM developers. ........ r70765 | georg.brandl | 2009-03-30 17:09:34 -0500 (Mon, 30 Mar 2009) | 1 line #5199: make warning about vars() assignment more visible. ........ r70769 | andrew.kuchling | 2009-03-30 17:29:53 -0500 (Mon, 30 Mar 2009) | 1 line Remove comment ........ r70770 | andrew.kuchling | 2009-03-30 17:30:20 -0500 (Mon, 30 Mar 2009) | 1 line Add several items and placeholders ........ r70771 | andrew.kuchling | 2009-03-30 17:31:11 -0500 (Mon, 30 Mar 2009) | 1 line Many edits ........ r70773 | georg.brandl | 2009-03-30 17:43:00 -0500 (Mon, 30 Mar 2009) | 1 line #5039: make it clear that the impl. note refers to CPython. ........ r70776 | andrew.kuchling | 2009-03-30 18:08:24 -0500 (Mon, 30 Mar 2009) | 1 line typo fix ........ r70777 | andrew.kuchling | 2009-03-30 18:09:46 -0500 (Mon, 30 Mar 2009) | 1 line Add more items ........ r70788 | andrew.kuchling | 2009-03-30 20:21:01 -0500 (Mon, 30 Mar 2009) | 1 line Add various items ........ r70789 | georg.brandl | 2009-03-30 20:25:15 -0500 (Mon, 30 Mar 2009) | 1 line Fix a wrong struct field assignment (docstring as closure). ........ r70824 | georg.brandl | 2009-03-31 10:43:20 -0500 (Tue, 31 Mar 2009) | 1 line #5519: remove reference to Kodos, which seems dead. ........ r70828 | georg.brandl | 2009-03-31 10:50:16 -0500 (Tue, 31 Mar 2009) | 1 line #5581: fget argument of abstractproperty is optional as well. ........ r70832 | georg.brandl | 2009-03-31 11:31:11 -0500 (Tue, 31 Mar 2009) | 1 line #1386675: specify WindowsError as the exception, because it has a winerror attribute that EnvironmentError doesnt have. ........ r70836 | georg.brandl | 2009-03-31 11:50:25 -0500 (Tue, 31 Mar 2009) | 1 line #5417: replace references to undocumented functions by ones to documented functions. ........ r70842 | georg.brandl | 2009-03-31 12:13:06 -0500 (Tue, 31 Mar 2009) | 1 line #970783: document PyObject_Generic[GS]etAttr. ........ r70851 | georg.brandl | 2009-03-31 13:26:55 -0500 (Tue, 31 Mar 2009) | 1 line #837577: note cryptic return value of spawn*e on invalid env dicts. ........ r70855 | georg.brandl | 2009-03-31 13:30:37 -0500 (Tue, 31 Mar 2009) | 1 line #5245: note that PyRun_SimpleString doesnt return on SystemExit. ........ r70857 | georg.brandl | 2009-03-31 13:33:10 -0500 (Tue, 31 Mar 2009) | 1 line #5227: note that Py_Main doesnt return on SystemExit. ........ r70866 | georg.brandl | 2009-03-31 14:06:57 -0500 (Tue, 31 Mar 2009) | 1 line #4882: document named group behavior a bit better. ........ r70867 | georg.brandl | 2009-03-31 14:10:35 -0500 (Tue, 31 Mar 2009) | 1 line #1096310: document usage of sys.__std*__ a bit better. ........ r70868 | georg.brandl | 2009-03-31 14:12:17 -0500 (Tue, 31 Mar 2009) | 1 line #5190: export make_option in __all__. ........ r70869 | georg.brandl | 2009-03-31 14:14:42 -0500 (Tue, 31 Mar 2009) | 1 line Fix-up unwanted change. ........ r70870 | georg.brandl | 2009-03-31 14:26:24 -0500 (Tue, 31 Mar 2009) | 1 line #4411: document mro() and __mro__. (I hope I got it right.) ........ r70871 | georg.brandl | 2009-03-31 14:30:56 -0500 (Tue, 31 Mar 2009) | 1 line #5618: fix typo. ........ r70872 | r.david.murray | 2009-03-31 14:31:17 -0500 (Tue, 31 Mar 2009) | 3 lines Delete out-of-date and little-known README from the test directory by consensus of devs at pycon sprint. ........ r70883 | georg.brandl | 2009-03-31 15:41:08 -0500 (Tue, 31 Mar 2009) | 1 line #1674032: return value of flag from Event.wait(). OKed by Guido. ........ r70885 | tarek.ziade | 2009-03-31 15:48:31 -0500 (Tue, 31 Mar 2009) | 1 line using log.warn for sys.stderr ........ r70893 | georg.brandl | 2009-03-31 15:56:32 -0500 (Tue, 31 Mar 2009) | 1 line #1530012: move TQS section before raw strings. ........ r70894 | benjamin.peterson | 2009-03-31 16:06:30 -0500 (Tue, 31 Mar 2009) | 1 line take the usual lock precautions around _active_limbo_lock ........ r70896 | georg.brandl | 2009-03-31 16:15:33 -0500 (Tue, 31 Mar 2009) | 1 line #5598: document DocFileSuite *args argument. ........ r70897 | benjamin.peterson | 2009-03-31 16:34:42 -0500 (Tue, 31 Mar 2009) | 1 line fix Thread.ident when it is the main thread or a dummy thread #5632 ........ r70903 | georg.brandl | 2009-03-31 16:45:18 -0500 (Tue, 31 Mar 2009) | 1 line #1676135: remove trailing slashes from --prefix argument. ........ r70905 | georg.brandl | 2009-03-31 17:03:40 -0500 (Tue, 31 Mar 2009) | 1 line #5563: more documentation for bdist_msi. ........ r70906 | georg.brandl | 2009-03-31 17:11:53 -0500 (Tue, 31 Mar 2009) | 1 line #1651995: fix _convert_ref for non-ASCII characters. ........ r70907 | georg.brandl | 2009-03-31 17:18:19 -0500 (Tue, 31 Mar 2009) | 1 line #3427: document correct return type for urlopen().info(). ........ r70915 | georg.brandl | 2009-03-31 17:40:16 -0500 (Tue, 31 Mar 2009) | 1 line #5018: remove confusing paragraph. ........ r70927 | georg.brandl | 2009-03-31 18:01:27 -0500 (Tue, 31 Mar 2009) | 1 line Dont shout to users. ........ r70933 | georg.brandl | 2009-03-31 19:04:33 -0500 (Tue, 31 Mar 2009) | 2 lines Issue #5635: Fix running test_sys with tracing enabled. ........ r70951 | georg.brandl | 2009-04-01 09:02:27 -0500 (Wed, 01 Apr 2009) | 1 line Add Maksim, who worked on several issues at the sprint. ........ r70960 | jesse.noller | 2009-04-01 11:42:19 -0500 (Wed, 01 Apr 2009) | 1 line Issue 3270: document Listener address restrictions on windows ........ r70962 | brett.cannon | 2009-04-01 12:07:16 -0500 (Wed, 01 Apr 2009) | 2 lines Ron DuPlain was given commit privileges at PyCon 2009 to work on 3to2. ........ r70963 | georg.brandl | 2009-04-01 12:46:01 -0500 (Wed, 01 Apr 2009) | 1 line #5655: fix docstring oversight. ........ r70964 | brett.cannon | 2009-04-01 12:52:13 -0500 (Wed, 01 Apr 2009) | 2 lines Paul Kippes was given commit privileges to work on 3to2. ........ r70998 | georg.brandl | 2009-04-01 16:54:21 -0500 (Wed, 01 Apr 2009) | 1 line In Pdb, stop assigning values to __builtin__._ which interferes with the one commonly installed by gettext. ........ r71001 | brett.cannon | 2009-04-01 18:01:12 -0500 (Wed, 01 Apr 2009) | 3 lines Add my initials to Misc/developers.txt. Names are now sorted by number of characters in the person's name. ........ r71006 | georg.brandl | 2009-04-01 18:32:17 -0500 (Wed, 01 Apr 2009) | 1 line Cache the f_locals dict of the current frame, since every access to frame.f_locals overrides its contents with the real locals which undoes modifications made by the debugging user. ........ r71008 | andrew.kuchling | 2009-04-01 19:02:14 -0500 (Wed, 01 Apr 2009) | 1 line Typo fix ........ r71010 | benjamin.peterson | 2009-04-01 19:11:52 -0500 (Wed, 01 Apr 2009) | 1 line fix markup ........ r71011 | benjamin.peterson | 2009-04-01 19:12:47 -0500 (Wed, 01 Apr 2009) | 1 line this should be :noindex: ........ r71019 | georg.brandl | 2009-04-01 21:00:01 -0500 (Wed, 01 Apr 2009) | 1 line Fix test_doctest, missed two assignments to curframe. ........ r71037 | r.david.murray | 2009-04-01 23:34:04 -0500 (Wed, 01 Apr 2009) | 6 lines Clarify that datetime strftime does not produce leap seconds and datetime strptime does not accept it in the strftime behavior section of the datetime docs. Closes issue 2568. ........ r71056 | georg.brandl | 2009-04-02 12:43:07 -0500 (Thu, 02 Apr 2009) | 2 lines Actually the displayhook should print the repr. ........ r71094 | vinay.sajip | 2009-04-03 05:23:18 -0500 (Fri, 03 Apr 2009) | 1 line Added warning about logging use from asynchronous signal handlers. ........ r71101 | andrew.kuchling | 2009-04-03 16:43:00 -0500 (Fri, 03 Apr 2009) | 1 line Add some items ........ r71102 | andrew.kuchling | 2009-04-03 16:44:49 -0500 (Fri, 03 Apr 2009) | 1 line Fix 'the the'; grammar fix ........ r71103 | andrew.kuchling | 2009-04-03 16:45:29 -0500 (Fri, 03 Apr 2009) | 1 line Fix 'the the' duplication ........ r71106 | vinay.sajip | 2009-04-03 16:58:16 -0500 (Fri, 03 Apr 2009) | 1 line Clarified warning about logging use from asynchronous signal handlers. ........ r71119 | raymond.hettinger | 2009-04-04 00:37:47 -0500 (Sat, 04 Apr 2009) | 1 line Add helpful link. ........ r71123 | r.david.murray | 2009-04-04 01:39:56 -0500 (Sat, 04 Apr 2009) | 2 lines Fix error in description of 'oct' (issue 5678). ........ r71149 | georg.brandl | 2009-04-04 08:42:39 -0500 (Sat, 04 Apr 2009) | 1 line #5642: clarify map() compatibility to the builtin. ........ r71150 | georg.brandl | 2009-04-04 08:45:49 -0500 (Sat, 04 Apr 2009) | 1 line #5601: clarify that webbrowser is not meant for file names. ........ r71203 | benjamin.peterson | 2009-04-04 18:46:34 -0500 (Sat, 04 Apr 2009) | 1 line note how using iter* are unsafe while mutating and document iter(dict) ........ r71212 | georg.brandl | 2009-04-05 05:24:20 -0500 (Sun, 05 Apr 2009) | 1 line #1742837: expand HTTP server docs, and fix SocketServer ones to document methods as methods, not functions. ........ r71214 | georg.brandl | 2009-04-05 05:29:57 -0500 (Sun, 05 Apr 2009) | 1 line Normalize spelling of Mac OS X. ........ r71215 | georg.brandl | 2009-04-05 05:32:26 -0500 (Sun, 05 Apr 2009) | 1 line Avoid sure signs of a diseased mind. ........ r71216 | georg.brandl | 2009-04-05 05:41:02 -0500 (Sun, 05 Apr 2009) | 1 line #1718017: document the relation of os.path and the posixpath, ntpath etc. modules better. ........ r71217 | georg.brandl | 2009-04-05 05:48:47 -0500 (Sun, 05 Apr 2009) | 1 line #1726172: dont raise an unexpected IndexError if a voidresp() call has an empty response. ........ r71221 | vinay.sajip | 2009-04-05 06:06:24 -0500 (Sun, 05 Apr 2009) | 1 line Issue #5695: Moved logging.captureWarnings() call inside with statement in WarningsTest.test_warnings. ........ r71240 | georg.brandl | 2009-04-05 09:40:06 -0500 (Sun, 05 Apr 2009) | 1 line #5370: doc update about unpickling objects with custom __getattr__ etc. methods. ........
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``PyLong_*`` found in :file:`intobject.h`. The abstract ``PyNumber_*`` APIs
Devil merge! Merged revisions 66561,66564,66580,66610,66614,66618,66624-66625,66628-66629,66643,66645,66660-66665 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r66561 | benjamin.peterson | 2008-09-22 17:13:29 -0500 (Mon, 22 Sep 2008) | 1 line clean up docs for platform's linux_distribution and dist functions ........ r66564 | benjamin.peterson | 2008-09-23 08:32:46 -0500 (Tue, 23 Sep 2008) | 1 line mention how to override boolean evaluation ........ r66580 | georg.brandl | 2008-09-24 04:47:55 -0500 (Wed, 24 Sep 2008) | 2 lines Indentation normalization. ........ r66610 | andrew.kuchling | 2008-09-24 12:27:55 -0500 (Wed, 24 Sep 2008) | 1 line Improve wording ........ r66614 | benjamin.peterson | 2008-09-24 17:11:59 -0500 (Wed, 24 Sep 2008) | 4 lines #3950 fix missing scale factors in turtle.py reviewers: Georg, Benjamin ........ r66618 | benjamin.peterson | 2008-09-25 15:35:45 -0500 (Thu, 25 Sep 2008) | 1 line add a NEWs entry for r66614 ........ r66624 | raymond.hettinger | 2008-09-25 18:31:52 -0500 (Thu, 25 Sep 2008) | 1 line Fix namedtuple bug reported by Glenn Linderman. Template did not form correctly if the field names were input in Unicode. ........ r66625 | benjamin.peterson | 2008-09-25 21:58:36 -0500 (Thu, 25 Sep 2008) | 1 line add the beginnings of a C-API 2 -> 3 porting guide ........ r66628 | benjamin.peterson | 2008-09-26 15:52:06 -0500 (Fri, 26 Sep 2008) | 1 line add an 'other options' section ........ r66629 | georg.brandl | 2008-09-26 16:15:21 -0500 (Fri, 26 Sep 2008) | 2 lines typos. ........ r66643 | andrew.kuchling | 2008-09-27 09:12:33 -0500 (Sat, 27 Sep 2008) | 1 line Add a last bunch of items ........ r66645 | benjamin.peterson | 2008-09-27 11:23:55 -0500 (Sat, 27 Sep 2008) | 1 line 2to3's api should be considered unstable ........ r66660 | andrew.kuchling | 2008-09-27 17:54:08 -0500 (Sat, 27 Sep 2008) | 1 line #3510: future-proof text ........ r66661 | benjamin.peterson | 2008-09-27 18:28:43 -0500 (Sat, 27 Sep 2008) | 1 line clarify a few things ........ r66662 | andrew.kuchling | 2008-09-27 19:15:27 -0500 (Sat, 27 Sep 2008) | 1 line #1579477: mention necessity to flush output before exec'ing ........ r66663 | andrew.kuchling | 2008-09-27 20:08:47 -0500 (Sat, 27 Sep 2008) | 1 line #1415508: Document two functions ........ r66664 | benjamin.peterson | 2008-09-27 20:51:36 -0500 (Sat, 27 Sep 2008) | 1 line better grammar ........ r66665 | benjamin.peterson | 2008-09-27 20:53:29 -0500 (Sat, 27 Sep 2008) | 1 line note the 2to3 -d could be useful for other refactoring ........
2008-09-27 23:06:32 -03:00
can also be used in some cases. ::
#include "Python.h"
#include "intobject.h"
static PyObject *
add_ints(PyObject *self, PyObject *args) {
int one, two;
PyObject *result;
if (!PyArg_ParseTuple(args, "ii:add_ints", &one, &two))
return NULL;
return PyInt_FromLong(one + two);
}
Module initialization and state
===============================
Python 3.0 has a revamped extension module initialization system. (See PEP
:pep:`3121`.) Instead of storing module state in globals, they should be stored
in an interpreter specific structure. Creating modules that act correctly in
both 2.x and 3.0 is tricky. The following simple example demonstrates how. ::
#include "Python.h"
struct module_state {
PyObject *error;
};
#if PY_MAJOR_VERSION >= 3
#define GETSTATE(m) ((struct module_state*)PyModule_GetState(m))
#else
#define GETSTATE(m) (&_state)
static struct module_state _state;
#endif
static PyObject *
error_out(PyObject *m) {
struct module_state *st = GETSTATE(m);
PyErr_SetString(st->error, "something bad happened");
return NULL;
}
static PyMethodDef myextension_methods[] = {
{"error_out", (PyCFunction)error_out, METH_NOARGS, NULL},
{NULL, NULL}
};
#if PY_MAJOR_VERSION >= 3
static int myextension_traverse(PyObject *m, visitproc visit, void *arg) {
Py_VISIT(GETSTATE(m)->error);
return 0;
}
static int myextension_clear(PyObject *m) {
Py_CLEAR(GETSTATE(m)->error);
return 0;
}
static struct PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
"myextension",
NULL,
sizeof(struct module_state),
myextension_methods,
NULL,
myextension_traverse,
myextension_clear,
NULL
};
#define INITERROR return NULL
PyObject *
PyInit_myextension(void)
#else
#define INITERROR return
void
initmyextension(void)
#endif
{
#if PY_MAJOR_VERSION >= 3
PyObject *module = PyModule_Create(&moduledef);
#else
PyObject *module = Py_InitModule("myextension", myextension_methods);
#endif
if (module == NULL)
INITERROR;
struct module_state *st = GETSTATE(module);
st->error = PyErr_NewException("myextension.Error", NULL, NULL);
if (st->error == NULL) {
Py_DECREF(module);
INITERROR;
}
#if PY_MAJOR_VERSION >= 3
return module;
#endif
}
Other options
=============
If you are writing a new extension module, you might consider `Cython
<http://www.cython.org>`_. It translates a Python-like language to C. The
extension modules it creates are compatible with Python 3.x and 2.x.