FazBrowse GitHub Viewer
|
Trending
|
URL:
|
Home
Tools:
[Download Repo ZIP]
[View Raw Code]
[Original HTTPS Page]
python-docs-de/extending/extending.po at 3.14 · python/python-docs-de · GitHub
python
python-docs-de
Repository navigation
Code
Issues
Pull requests
2
(2)
Actions
Security and quality
Insights
Expand file tree
Breadcrumbs
python-docs-de
/
extending
/
extending.po
Copy path
More file actions
More file actions
Latest commit
History
History
History
2004 lines (1778 loc) · 72.1 KB
Breadcrumbs
python-docs-de
/
extending
/
extending.po
Copy path
File metadata and controls
2004 lines (1778 loc) · 72.1 KB
Raw
Copy raw file
Download raw file
Open symbols panel
Edit and raw actions
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#
SOME DESCRIPTIVE TITLE.
#
Copyright (C) 2001 Python Software Foundation
#
This file is distributed under the same license as the Python package.
#
FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
#
#
Translators:
#
python-doc bot, 2025
#
msgid ""
msgstr ""
"
Project-Id-Version
:
Python 3.14\n
"
"
Report-Msgid-Bugs-To
:
\n
"
"
POT-Creation-Date
:
2026-09-05 16:53+0200\n
"
"
PO-Revision-Date
:
2025-09-16 00:00+0000\n
"
"
Last-Translator
:
python-doc bot, 2025\n
"
"
Language-Team
:
German (https://app.transifex.com/python-doc/teams/5390/de/)\n
"
"
Language
:
de\n
"
"
MIME-Version
:
1.0\n
"
"
Content-Type
:
text/plain; charset=UTF-8\n
"
"
Content-Transfer-Encoding
:
8bit\n
"
"
Plural-Forms
:
nplurals=2; plural=(n != 1);\n
"
#:
../../extending/extending.rst:8
msgid
"Extending Python with C or C++"
msgstr
""
#:
../../extending/extending.rst:10
msgid
""
"It is quite easy to add new built-in modules to Python, if you know how to "
"program in C. Such :dfn:`extension modules` can do two things that can't be "
"done directly in Python: they can implement new built-in object types, and "
"they can call C library functions and system calls."
msgstr
""
#:
../../extending/extending.rst:15
msgid
""
"To support extensions, the Python API (Application Programmers Interface) "
"defines a set of functions, macros and variables that provide access to most "
"aspects of the Python run-time system. The Python API is incorporated in a "
"C source file by including the header ``
\"
Python.h
\"
``."
msgstr
""
#:
../../extending/extending.rst:20
msgid
""
"The compilation of an extension module depends on its intended use as well "
"as on your system setup; details are given in later chapters."
msgstr
""
#:
../../extending/extending.rst:25
msgid
""
"The C extension interface is specific to CPython, and extension modules do "
"not work on other Python implementations. In many cases, it is possible to "
"avoid writing C extensions and preserve portability to other "
"implementations. For example, if your use case is calling C library "
"functions or system calls, you should consider using the :mod:`ctypes` "
"module or the `cffi <https://cffi.readthedocs.io/>`_ library rather than "
"writing custom C code. These modules let you write Python code to interface "
"with C code and are more portable between implementations of Python than "
"writing and compiling a C extension module."
msgstr
""
#:
../../extending/extending.rst:40
msgid
"A Simple Example"
msgstr
""
#:
../../extending/extending.rst:42
msgid
""
"Let's create an extension module called ``spam`` (the favorite food of Monty "
"Python fans...) and let's say we want to create a Python interface to the C "
"library function :c:func:`system` [#]_. This function takes a null-"
"terminated character string as argument and returns an integer. We want "
"this function to be callable from Python as follows:"
msgstr
""
#:
../../extending/extending.rst:48
msgid
""
">>> import spam\n"
">>> status = spam.system(
\"
ls -l
\"
)"
msgstr
""
#:
../../extending/extending.rst:53
msgid
""
"Begin by creating a file :file:`spammodule.c`. (Historically, if a module "
"is called ``spam``, the C file containing its implementation is called :file:"
"`spammodule.c`; if the module name is very long, like ``spammify``, the "
"module name can be just :file:`spammify.c`.)"
msgstr
""
#:
../../extending/extending.rst:58
msgid
"The first two lines of our file can be::"
msgstr
""
#:
../../extending/extending.rst:60
../../extending/extending.rst:704
msgid
""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>"
msgstr
""
#:
../../extending/extending.rst:63
msgid
""
"which pulls in the Python API (you can add a comment describing the purpose "
"of the module and a copyright notice if you like)."
msgstr
""
#:
../../extending/extending.rst:68
msgid
""
"Since Python may define some pre-processor definitions which affect the "
"standard headers on some systems, you *must* include :file:`Python.h` before "
"any standard headers are included."
msgstr
""
#:
../../extending/extending.rst:72
msgid
""
"``#define PY_SSIZE_T_CLEAN`` was used to indicate that ``Py_ssize_t`` should "
"be used in some APIs instead of ``int``. It is not necessary since Python "
"3.13, but we keep it here for backward compatibility. See :ref:`arg-parsing-"
"string-and-buffers` for a description of this macro."
msgstr
""
#:
../../extending/extending.rst:77
msgid
""
"All user-visible symbols defined by :file:`Python.h` have a prefix of ``Py`` "
"or ``PY``, except those defined in standard header files."
msgstr
""
#:
../../extending/extending.rst:82
msgid
""
"For backward compatibility, :file:`Python.h` includes several standard "
"header files. C extensions should include the standard headers that they "
"use, and should not rely on these implicit includes. If using the limited C "
"API version 3.13 or newer, the implicit includes are:"
msgstr
""
#:
../../extending/extending.rst:87
msgid
"``<assert.h>``"
msgstr
""
#:
../../extending/extending.rst:88
msgid
"``<intrin.h>`` (on Windows)"
msgstr
""
#:
../../extending/extending.rst:89
msgid
"``<inttypes.h>``"
msgstr
""
#:
../../extending/extending.rst:90
msgid
"``<limits.h>``"
msgstr
""
#:
../../extending/extending.rst:91
msgid
"``<math.h>``"
msgstr
""
#:
../../extending/extending.rst:92
msgid
"``<stdarg.h>``"
msgstr
""
#:
../../extending/extending.rst:93
msgid
"``<wchar.h>``"
msgstr
""
#:
../../extending/extending.rst:94
msgid
"``<sys/types.h>`` (if present)"
msgstr
""
#:
../../extending/extending.rst:96
msgid
""
"If :c:macro:`Py_LIMITED_API` is not defined, or is set to version 3.12 or "
"older, the headers below are also included:"
msgstr
""
#:
../../extending/extending.rst:99
msgid
"``<ctype.h>``"
msgstr
""
#:
../../extending/extending.rst:100
msgid
"``<unistd.h>`` (on POSIX)"
msgstr
""
#:
../../extending/extending.rst:102
msgid
""
"If :c:macro:`Py_LIMITED_API` is not defined, or is set to version 3.10 or "
"older, the headers below are also included:"
msgstr
""
#:
../../extending/extending.rst:105
msgid
"``<errno.h>``"
msgstr
""
#:
../../extending/extending.rst:106
msgid
"``<stdio.h>``"
msgstr
""
#:
../../extending/extending.rst:107
msgid
"``<stdlib.h>``"
msgstr
""
#:
../../extending/extending.rst:108
msgid
"``<string.h>``"
msgstr
""
#:
../../extending/extending.rst:110
msgid
""
"The next thing we add to our module file is the C function that will be "
"called when the Python expression ``spam.system(string)`` is evaluated "
"(we'll see shortly how it ends up being called)::"
msgstr
""
#:
../../extending/extending.rst:114
msgid
""
"static PyObject *\n"
"spam_system(PyObject *self, PyObject *args)\n"
"{\n"
" const char *command;\n"
" int sts;\n"
"\n"
" if (!PyArg_ParseTuple(args,
\"
s
\"
, &command))\n"
" return NULL;\n"
" sts = system(command);\n"
" return PyLong_FromLong(sts);\n"
"}"
msgstr
""
#:
../../extending/extending.rst:126
msgid
""
"There is a straightforward translation from the argument list in Python (for "
"example, the single expression ``
\"
ls -l
\"
``) to the arguments passed to the "
"C function. The C function always has two arguments, conventionally named "
"*self* and *args*."
msgstr
""
#:
../../extending/extending.rst:131
msgid
""
"The *self* argument points to the module object for module-level functions; "
"for a method it would point to the object instance."
msgstr
""
#:
../../extending/extending.rst:134
msgid
""
"The *args* argument will be a pointer to a Python tuple object containing "
"the arguments. Each item of the tuple corresponds to an argument in the "
"call's argument list. The arguments are Python objects --- in order to do "
"anything with them in our C function we have to convert them to C values. "
"The function :c:func:`PyArg_ParseTuple` in the Python API checks the "
"argument types and converts them to C values. It uses a template string to "
"determine the required types of the arguments as well as the types of the C "
"variables into which to store the converted values. More about this later."
msgstr
""
#:
../../extending/extending.rst:143
msgid
""
":c:func:`PyArg_ParseTuple` returns true (nonzero) if all arguments have the "
"right type and its components have been stored in the variables whose "
"addresses are passed. It returns false (zero) if an invalid argument list "
"was passed. In the latter case it also raises an appropriate exception so "
"the calling function can return ``NULL`` immediately (as we saw in the "
"example)."
msgstr
""
#:
../../extending/extending.rst:153
msgid
"Intermezzo: Errors and Exceptions"
msgstr
""
#:
../../extending/extending.rst:155
msgid
""
"An important convention throughout the Python interpreter is the following: "
"when a function fails, it should set an exception condition and return an "
"error value (usually ``-1`` or a ``NULL`` pointer). Exception information "
"is stored in three members of the interpreter's thread state. These are "
"``NULL`` if there is no exception. Otherwise they are the C equivalents of "
"the members of the Python tuple returned by :meth:`sys.exc_info`. These are "
"the exception type, exception instance, and a traceback object. It is "
"important to know about them to understand how errors are passed around."
msgstr
""
#:
../../extending/extending.rst:164
msgid
""
"The Python API defines a number of functions to set various types of "
"exceptions."
msgstr
""
#:
../../extending/extending.rst:166
msgid
""
"The most common one is :c:func:`PyErr_SetString`. Its arguments are an "
"exception object and a C string. The exception object is usually a "
"predefined object like :c:data:`PyExc_ZeroDivisionError`. The C string "
"indicates the cause of the error and is converted to a Python string object "
"and stored as the
\"
associated value
\"
of the exception."
msgstr
""
#:
../../extending/extending.rst:172
msgid
""
"Another useful function is :c:func:`PyErr_SetFromErrno`, which only takes an "
"exception argument and constructs the associated value by inspection of the "
"global variable :c:data:`errno`. The most general function is :c:func:"
"`PyErr_SetObject`, which takes two object arguments, the exception and its "
"associated value. You don't need to :c:func:`Py_INCREF` the objects passed "
"to any of these functions."
msgstr
""
#:
../../extending/extending.rst:179
msgid
""
"You can test non-destructively whether an exception has been set with :c:"
"func:`PyErr_Occurred`. This returns the current exception object, or "
"``NULL`` if no exception has occurred. You normally don't need to call :c:"
"func:`PyErr_Occurred` to see whether an error occurred in a function call, "
"since you should be able to tell from the return value."
msgstr
""
#:
../../extending/extending.rst:185
msgid
""
"When a function *f* that calls another function *g* detects that the latter "
"fails, *f* should itself return an error value (usually ``NULL`` or "
"``-1``). It should *not* call one of the ``PyErr_*`` functions --- one has "
"already been called by *g*. *f*'s caller is then supposed to also return an "
"error indication to *its* caller, again *without* calling ``PyErr_*``, and "
"so on --- the most detailed cause of the error was already reported by the "
"function that first detected it. Once the error reaches the Python "
"interpreter's main loop, this aborts the currently executing Python code and "
"tries to find an exception handler specified by the Python programmer."
msgstr
""
#:
../../extending/extending.rst:195
msgid
""
"(There are situations where a module can actually give a more detailed error "
"message by calling another ``PyErr_*`` function, and in such cases it is "
"fine to do so. As a general rule, however, this is not necessary, and can "
"cause information about the cause of the error to be lost: most operations "
"can fail for a variety of reasons.)"
msgstr
""
#:
../../extending/extending.rst:201
msgid
""
"To ignore an exception set by a function call that failed, the exception "
"condition must be cleared explicitly by calling :c:func:`PyErr_Clear`. The "
"only time C code should call :c:func:`PyErr_Clear` is if it doesn't want to "
"pass the error on to the interpreter but wants to handle it completely by "
"itself (possibly by trying something else, or pretending nothing went wrong)."
msgstr
""
#:
../../extending/extending.rst:207
msgid
""
"Every failing :c:func:`malloc` call must be turned into an exception --- the "
"direct caller of :c:func:`malloc` (or :c:func:`realloc`) must call :c:func:"
"`PyErr_NoMemory` and return a failure indicator itself. All the object-"
"creating functions (for example, :c:func:`PyLong_FromLong`) already do this, "
"so this note is only relevant to those who call :c:func:`malloc` directly."
msgstr
""
#:
../../extending/extending.rst:213
msgid
""
"Also note that, with the important exception of :c:func:`PyArg_ParseTuple` "
"and friends, functions that return an integer status usually return a "
"positive value or zero for success and ``-1`` for failure, like Unix system "
"calls."
msgstr
""
#:
../../extending/extending.rst:217
msgid
""
"Finally, be careful to clean up garbage (by making :c:func:`Py_XDECREF` or :"
"c:func:`Py_DECREF` calls for objects you have already created) when you "
"return an error indicator!"
msgstr
""
#:
../../extending/extending.rst:221
msgid
""
"The choice of which exception to raise is entirely yours. There are "
"predeclared C objects corresponding to all built-in Python exceptions, such "
"as :c:data:`PyExc_ZeroDivisionError`, which you can use directly. Of course, "
"you should choose exceptions wisely --- don't use :c:data:`PyExc_TypeError` "
"to mean that a file couldn't be opened (that should probably be :c:data:"
"`PyExc_OSError`). If something's wrong with the argument list, the :c:func:"
"`PyArg_ParseTuple` function usually raises :c:data:`PyExc_TypeError`. If "
"you have an argument whose value must be in a particular range or must "
"satisfy other conditions, :c:data:`PyExc_ValueError` is appropriate."
msgstr
""
#:
../../extending/extending.rst:231
msgid
""
"You can also define a new exception that is unique to your module. The "
"simplest way to do this is to declare a static global object variable at the "
"beginning of the file::"
msgstr
""
#:
../../extending/extending.rst:235
msgid
"static PyObject *SpamError = NULL;"
msgstr
""
#:
../../extending/extending.rst:237
msgid
""
"and initialize it by calling :c:func:`PyErr_NewException` in the module's :c:"
"data:`Py_mod_exec` function (:c:func:`!spam_module_exec`)::"
msgstr
""
#:
../../extending/extending.rst:240
msgid
"SpamError = PyErr_NewException(
\"
spam.error
\"
, NULL, NULL);"
msgstr
""
#:
../../extending/extending.rst:242
msgid
""
"Since :c:data:`!SpamError` is a global variable, it will be overwritten "
"every time the module is reinitialized, when the :c:data:`Py_mod_exec` "
"function is called."
msgstr
""
#:
../../extending/extending.rst:245
msgid
""
"For now, let's avoid the issue: we will block repeated initialization by "
"raising an :py:exc:`ImportError`::"
msgstr
""
#:
../../extending/extending.rst:248
msgid
""
"static PyObject *SpamError = NULL;\n"
"\n"
"static int\n"
"spam_module_exec(PyObject *m)\n"
"{\n"
" if (SpamError != NULL) {\n"
" PyErr_SetString(PyExc_ImportError,\n"
"
\"
cannot initialize spam module more than once
\"
);\n"
" return -1;\n"
" }\n"
" SpamError = PyErr_NewException(
\"
spam.error
\"
, NULL, NULL);\n"
" if (PyModule_AddObjectRef(m,
\"
SpamError
\"
, SpamError) < 0) {\n"
" return -1;\n"
" }\n"
"\n"
" return 0;\n"
"}\n"
"\n"
"static PyModuleDef_Slot spam_module_slots[] = {\n"
" {Py_mod_exec, spam_module_exec},\n"
" {0, NULL}\n"
"};\n"
"\n"
"static struct PyModuleDef spam_module = {\n"
" .m_base = PyModuleDef_HEAD_INIT,\n"
" .m_name =
\"
spam
\"
,\n"
" .m_size = 0, // non-negative\n"
" .m_slots = spam_module_slots,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_spam(void)\n"
"{\n"
" return PyModuleDef_Init(&spam_module);\n"
"}"
msgstr
""
#:
../../extending/extending.rst:284
msgid
""
"Note that the Python name for the exception object is :exc:`!spam.error`. "
"The :c:func:`PyErr_NewException` function may create a class with the base "
"class being :exc:`Exception` (unless another class is passed in instead of "
"``NULL``), described in :ref:`bltin-exceptions`."
msgstr
""
#:
../../extending/extending.rst:289
msgid
""
"Note also that the :c:data:`!SpamError` variable retains a reference to the "
"newly created exception class; this is intentional! Since the exception "
"could be removed from the module by external code, an owned reference to the "
"class is needed to ensure that it will not be discarded, causing :c:data:`!"
"SpamError` to become a dangling pointer. Should it become a dangling "
"pointer, C code which raises the exception could cause a core dump or other "
"unintended side effects."
msgstr
""
#:
../../extending/extending.rst:296
msgid
""
"For now, the :c:func:`Py_DECREF` call to remove this reference is missing. "
"Even when the Python interpreter shuts down, the global :c:data:`!SpamError` "
"variable will not be garbage-collected. It will
\"
leak
\"
. We did, however, "
"ensure that this will happen at most once per process."
msgstr
""
#:
../../extending/extending.rst:301
msgid
""
"We discuss the use of :c:macro:`PyMODINIT_FUNC` as a function return type "
"later in this sample."
msgstr
""
#:
../../extending/extending.rst:304
msgid
""
"The :exc:`!spam.error` exception can be raised in your extension module "
"using a call to :c:func:`PyErr_SetString` as shown below::"
msgstr
""
#:
../../extending/extending.rst:307
msgid
""
"static PyObject *\n"
"spam_system(PyObject *self, PyObject *args)\n"
"{\n"
" const char *command;\n"
" int sts;\n"
"\n"
" if (!PyArg_ParseTuple(args,
\"
s
\"
, &command))\n"
" return NULL;\n"
" sts = system(command);\n"
" if (sts < 0) {\n"
" PyErr_SetString(SpamError,
\"
System command failed
\"
);\n"
" return NULL;\n"
" }\n"
" return PyLong_FromLong(sts);\n"
"}"
msgstr
""
#:
../../extending/extending.rst:327
msgid
"Back to the Example"
msgstr
""
#:
../../extending/extending.rst:329
msgid
""
"Going back to our example function, you should now be able to understand "
"this statement::"
msgstr
""
#:
../../extending/extending.rst:332
msgid
""
"if (!PyArg_ParseTuple(args,
\"
s
\"
, &command))\n"
" return NULL;"
msgstr
""
#:
../../extending/extending.rst:335
msgid
""
"It returns ``NULL`` (the error indicator for functions returning object "
"pointers) if an error is detected in the argument list, relying on the "
"exception set by :c:func:`PyArg_ParseTuple`. Otherwise the string value of "
"the argument has been copied to the local variable :c:data:`!command`. This "
"is a pointer assignment and you are not supposed to modify the string to "
"which it points (so in Standard C, the variable :c:data:`!command` should "
"properly be declared as ``const char *command``)."
msgstr
""
#:
../../extending/extending.rst:343
msgid
""
"The next statement is a call to the Unix function :c:func:`system`, passing "
"it the string we just got from :c:func:`PyArg_ParseTuple`::"
msgstr
""
#:
../../extending/extending.rst:346
msgid
"sts = system(command);"
msgstr
""
#:
../../extending/extending.rst:348
msgid
""
"Our :func:`!spam.system` function must return the value of :c:data:`!sts` as "
"a Python object. This is done using the function :c:func:"
"`PyLong_FromLong`. ::"
msgstr
""
#:
../../extending/extending.rst:351
msgid
"return PyLong_FromLong(sts);"
msgstr
""
#:
../../extending/extending.rst:353
msgid
""
"In this case, it will return an integer object. (Yes, even integers are "
"objects on the heap in Python!)"
msgstr
""
#:
../../extending/extending.rst:356
msgid
""
"If you have a C function that returns no useful argument (a function "
"returning :c:expr:`void`), the corresponding Python function must return "
"``None``. You need this idiom to do so (which is implemented by the :c:"
"macro:`Py_RETURN_NONE` macro)::"
msgstr
""
#:
../../extending/extending.rst:361
msgid
""
"Py_INCREF(Py_None);\n"
"return Py_None;"
msgstr
""
#:
../../extending/extending.rst:364
msgid
""
":c:data:`Py_None` is the C name for the special Python object ``None``. It "
"is a genuine Python object rather than a ``NULL`` pointer, which means "
"
\"
error
\"
in most contexts, as we have seen."
msgstr
""
#:
../../extending/extending.rst:372
msgid
"The Module's Method Table and Initialization Function"
msgstr
""
#:
../../extending/extending.rst:374
msgid
""
"I promised to show how :c:func:`!spam_system` is called from Python "
"programs. First, we need to list its name and address in a
\"
method table
\"
::"
msgstr
""
#:
../../extending/extending.rst:377
msgid
""
"static PyMethodDef spam_methods[] = {\n"
" ...\n"
" {
\"
system
\"
, spam_system, METH_VARARGS,\n"
"
\"
Execute a shell command.
\"
},\n"
" ...\n"
" {NULL, NULL, 0, NULL} /* Sentinel */\n"
"};"
msgstr
""
#:
../../extending/extending.rst:385
msgid
""
"Note the third entry (``METH_VARARGS``). This is a flag telling the "
"interpreter the calling convention to be used for the C function. It should "
"normally always be ``METH_VARARGS`` or ``METH_VARARGS | METH_KEYWORDS``; a "
"value of ``0`` means that an obsolete variant of :c:func:`PyArg_ParseTuple` "
"is used."
msgstr
""
#:
../../extending/extending.rst:390
msgid
""
"When using only ``METH_VARARGS``, the function should expect the Python-"
"level parameters to be passed in as a tuple acceptable for parsing via :c:"
"func:`PyArg_ParseTuple`; more information on this function is provided below."
msgstr
""
#:
../../extending/extending.rst:394
msgid
""
"The :c:macro:`METH_KEYWORDS` bit may be set in the third field if keyword "
"arguments should be passed to the function. In this case, the C function "
"should accept a third ``PyObject *`` parameter which will be a dictionary of "
"keywords. Use :c:func:`PyArg_ParseTupleAndKeywords` to parse the arguments "
"to such a function."
msgstr
""
#:
../../extending/extending.rst:400
msgid
""
"The method table must be referenced in the module definition structure::"
msgstr
""
#:
../../extending/extending.rst:402
msgid
""
"static struct PyModuleDef spam_module = {\n"
" ...\n"
" .m_methods = spam_methods,\n"
" ...\n"
"};"
msgstr
""
#:
../../extending/extending.rst:408
msgid
""
"This structure, in turn, must be passed to the interpreter in the module's "
"initialization function. The initialization function must be named :c:func:"
"`!PyInit_name`, where *name* is the name of the module, and should be the "
"only non-
\\
``static`` item defined in the module file::"
msgstr
""
#:
../../extending/extending.rst:413
msgid
""
"PyMODINIT_FUNC\n"
"PyInit_spam(void)\n"
"{\n"
" return PyModuleDef_Init(&spam_module);\n"
"}"
msgstr
""
#:
../../extending/extending.rst:419
msgid
""
"Note that :c:macro:`PyMODINIT_FUNC` declares the function as ``PyObject *`` "
"return type, declares any special linkage declarations required by the "
"platform, and for C++ declares the function as ``extern
\"
C
\"
``."
msgstr
""
#:
../../extending/extending.rst:423
msgid
""
":c:func:`!PyInit_spam` is called when each interpreter imports its module :"
"mod:`!spam` for the first time. (See below for comments about embedding "
"Python.) A pointer to the module definition must be returned via :c:func:"
"`PyModuleDef_Init`, so that the import machinery can create the module and "
"store it in ``sys.modules``."
msgstr
""
#:
../../extending/extending.rst:428
msgid
""
"When embedding Python, the :c:func:`!PyInit_spam` function is not called "
"automatically unless there's an entry in the :c:data:`PyImport_Inittab` "
"table. To add the module to the initialization table, use :c:func:"
"`PyImport_AppendInittab`, optionally followed by an import of the module::"
msgstr
""
#:
../../extending/extending.rst:433
msgid
""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"\n"
"int\n"
"main(int argc, char *argv[])\n"
"{\n"
" PyStatus status;\n"
" PyConfig config;\n"
" PyConfig_InitPythonConfig(&config);\n"
"\n"
" /* Add a built-in module, before Py_Initialize */\n"
" if (PyImport_AppendInittab(
\"
spam
\"
, PyInit_spam) == -1) {\n"
" fprintf(stderr,
\"
Error: could not extend in-built modules "
"table
\\
n
\"
);\n"
" exit(1);\n"
" }\n"
"\n"
" /* Pass argv[0] to the Python interpreter */\n"
" status = PyConfig_SetBytesString(&config, &config.program_name, "
"argv[0]);\n"
" if (PyStatus_Exception(status)) {\n"
" goto exception;\n"
" }\n"
"\n"
" /* Initialize the Python interpreter. Required.\n"
" If this step fails, it will be a fatal error. */\n"
" status = Py_InitializeFromConfig(&config);\n"
" if (PyStatus_Exception(status)) {\n"
" goto exception;\n"
" }\n"
" PyConfig_Clear(&config);\n"
"\n"
" /* Optionally import the module; alternatively,\n"
" import can be deferred until the embedded script\n"
" imports it. */\n"
" PyObject *pmodule = PyImport_ImportModule(
\"
spam
\"
);\n"
" if (!pmodule) {\n"
" PyErr_Print();\n"
" fprintf(stderr,
\"
Error: could not import module 'spam'
\\
n
\"
);\n"
" }\n"
"\n"
" // ... use Python C API here ...\n"
"\n"
" return 0;\n"
"\n"
" exception:\n"
" PyConfig_Clear(&config);\n"
" Py_ExitStatusException(status);\n"
"}"
msgstr
""
#:
../../extending/extending.rst:483
msgid
""
"If you declare a global variable or a local static one, the module may "
"experience unintended side-effects on re-initialisation, for example when "
"removing entries from ``sys.modules`` or importing compiled modules into "
"multiple interpreters within a process (or following a :c:func:`fork` "
"without an intervening :c:func:`exec`). If module state is not yet fully :"
"ref:`isolated <isolating-extensions-howto>`, authors should consider marking "
"the module as having no support for subinterpreters (via :c:macro:"
"`Py_MOD_MULTIPLE_INTERPRETERS_NOT_SUPPORTED`)."
msgstr
""
#:
../../extending/extending.rst:492
msgid
""
"A more substantial example module is included in the Python source "
"distribution as :file:`Modules/xxlimited.c`. This file may be used as a "
"template or simply read as an example."
msgstr
""
#:
../../extending/extending.rst:500
msgid
"Compilation and Linkage"
msgstr
""
#:
../../extending/extending.rst:502
msgid
""
"There are two more things to do before you can use your new extension: "
"compiling and linking it with the Python system. If you use dynamic "
"loading, the details may depend on the style of dynamic loading your system "
"uses; see the chapters about building extension modules (chapter :ref:"
"`building`) and additional information that pertains only to building on "
"Windows (chapter :ref:`building-on-windows`) for more information about this."
msgstr
""
#:
../../extending/extending.rst:509
msgid
""
"If you can't use dynamic loading, or if you want to make your module a "
"permanent part of the Python interpreter, you will have to change the "
"configuration setup and rebuild the interpreter. Luckily, this is very "
"simple on Unix: just place your file (:file:`spammodule.c` for example) in "
"the :file:`Modules/` directory of an unpacked source distribution, add a "
"line to the file :file:`Modules/Setup.local` describing your file:"
msgstr
""
#:
../../extending/extending.rst:516
msgid
"spam spammodule.o"
msgstr
""
#:
../../extending/extending.rst:520
msgid
""
"and rebuild the interpreter by running :program:`make` in the toplevel "
"directory. You can also run :program:`make` in the :file:`Modules/` "
"subdirectory, but then you must first rebuild :file:`Makefile` there by "
"running ':program:`make` Makefile'. (This is necessary each time you change "
"the :file:`Setup` file.)"
msgstr
""
#:
../../extending/extending.rst:526
msgid
""
"If your module requires additional libraries to link with, these can be "
"listed on the line in the configuration file as well, for instance:"
msgstr
""
#:
../../extending/extending.rst:529
msgid
"spam spammodule.o -lX11"
msgstr
""
#:
../../extending/extending.rst:537
msgid
"Calling Python Functions from C"
msgstr
""
#:
../../extending/extending.rst:539
msgid
""
"So far we have concentrated on making C functions callable from Python. The "
"reverse is also useful: calling Python functions from C. This is especially "
"the case for libraries that support so-called
\"
callback
\"
functions. If a "
"C interface makes use of callbacks, the equivalent Python often needs to "
"provide a callback mechanism to the Python programmer; the implementation "
"will require calling the Python callback functions from a C callback. Other "
"uses are also imaginable."
msgstr
""
#:
../../extending/extending.rst:547
msgid
""
"Fortunately, the Python interpreter is easily called recursively, and there "
"is a standard interface to call a Python function. (If you're interested in "
"how to call the Python parser with a particular string as input, see :ref:"
"`veryhigh`.)"
msgstr
""
#:
../../extending/extending.rst:551
msgid
""
"Calling a Python function is easy. First, the Python program must somehow "
"pass you the Python function object. You should provide a function (or some "
"other interface) to do this. When this function is called, save a pointer "
"to the Python function object (be careful to :c:func:`Py_INCREF` it!) in a "
"global variable --- or wherever you see fit. For example, the following "
"function might be part of a module definition::"
msgstr
""
#:
../../extending/extending.rst:558
msgid
""
"static PyObject *my_callback = NULL;\n"
"\n"
"static PyObject *\n"
"my_set_callback(PyObject *dummy, PyObject *args)\n"
"{\n"
" PyObject *result = NULL;\n"
" PyObject *temp;\n"
"\n"
" if (PyArg_ParseTuple(args,
\"
O:set_callback
\"
, &temp)) {\n"
" if (!PyCallable_Check(temp)) {\n"
" PyErr_SetString(PyExc_TypeError,
\"
parameter must be "
"callable
\"
);\n"
" return NULL;\n"
" }\n"
" Py_XINCREF(temp); /* Add a reference to new callback */\n"
" Py_XDECREF(my_callback); /* Dispose of previous callback */\n"
" my_callback = temp; /* Remember new callback */\n"
" /* Boilerplate to return
\"
None
\"
*/\n"
" Py_INCREF(Py_None);\n"
" result = Py_None;\n"
" }\n"
" return result;\n"
"}"
msgstr
""
#:
../../extending/extending.rst:581
msgid
""
"This function must be registered with the interpreter using the :c:macro:"
"`METH_VARARGS` flag; this is described in section :ref:`methodtable`. The :"
"c:func:`PyArg_ParseTuple` function and its arguments are documented in "
"section :ref:`parsetuple`."
msgstr
""
#:
../../extending/extending.rst:586
msgid
""
"The macros :c:func:`Py_XINCREF` and :c:func:`Py_XDECREF` increment/decrement "
"the reference count of an object and are safe in the presence of ``NULL`` "
"pointers (but note that *temp* will not be ``NULL`` in this context). More "
"info on them in section :ref:`refcounts`."
msgstr
""
#:
../../extending/extending.rst:593
msgid
""
"Later, when it is time to call the function, you call the C function :c:func:"
"`PyObject_CallObject`. This function has two arguments, both pointers to "
"arbitrary Python objects: the Python function, and the argument list. The "
"argument list must always be a tuple object, whose length is the number of "
"arguments. To call the Python function with no arguments, pass in ``NULL``, "
"or an empty tuple; to call it with one argument, pass a singleton tuple. :c:"
"func:`Py_BuildValue` returns a tuple when its format string consists of zero "
"or more format codes between parentheses. For example::"
msgstr
""
#:
../../extending/extending.rst:602
msgid
""
"int arg;\n"
"PyObject *arglist;\n"
"PyObject *result;\n"
"...\n"
"arg = 123;\n"
"...\n"
"/* Time to call the callback */\n"
"arglist = Py_BuildValue(
\"
(i)
\"
, arg);\n"
"result = PyObject_CallObject(my_callback, arglist);\n"
"Py_DECREF(arglist);"
msgstr
""
#:
../../extending/extending.rst:613
msgid
""
":c:func:`PyObject_CallObject` returns a Python object pointer: this is the "
"return value of the Python function. :c:func:`PyObject_CallObject` is "
"
\"
reference-count-neutral
\"
with respect to its arguments. In the example a "
"new tuple was created to serve as the argument list, which is :c:func:"
"`Py_DECREF`
\\
-ed immediately after the :c:func:`PyObject_CallObject` call."
msgstr
""
#:
../../extending/extending.rst:620
msgid
""
"The return value of :c:func:`PyObject_CallObject` is
\"
new
\"
: either it is a "
"brand new object, or it is an existing object whose reference count has been "
"incremented. So, unless you want to save it in a global variable, you "
"should somehow :c:func:`Py_DECREF` the result, even (especially!) if you are "
"not interested in its value."
msgstr
""
#:
../../extending/extending.rst:626
msgid
""
"Before you do this, however, it is important to check that the return value "
"isn't ``NULL``. If it is, the Python function terminated by raising an "
"exception. If the C code that called :c:func:`PyObject_CallObject` is called "
"from Python, it should now return an error indication to its Python caller, "
"so the interpreter can print a stack trace, or the calling Python code can "
"handle the exception. If this is not possible or desirable, the exception "
"should be cleared by calling :c:func:`PyErr_Clear`. For example::"
msgstr
""
#:
../../extending/extending.rst:634
msgid
""
"if (result == NULL)\n"
" return NULL; /* Pass error back */\n"
"...use result...\n"
"Py_DECREF(result);"
msgstr
""
#:
../../extending/extending.rst:639
msgid
""
"Depending on the desired interface to the Python callback function, you may "
"also have to provide an argument list to :c:func:`PyObject_CallObject`. In "
"some cases the argument list is also provided by the Python program, through "
"the same interface that specified the callback function. It can then be "
"saved and used in the same manner as the function object. In other cases, "
"you may have to construct a new tuple to pass as the argument list. The "
"simplest way to do this is to call :c:func:`Py_BuildValue`. For example, if "
"you want to pass an integral event code, you might use the following code::"
msgstr
""
#:
../../extending/extending.rst:648
msgid
""
"PyObject *arglist;\n"
"...\n"
"arglist = Py_BuildValue(
\"
(l)
\"
, eventcode);\n"
"result = PyObject_CallObject(my_callback, arglist);\n"
"Py_DECREF(arglist);\n"
"if (result == NULL)\n"
" return NULL; /* Pass error back */\n"
"/* Here maybe use the result */\n"
"Py_DECREF(result);"
msgstr
""
#:
../../extending/extending.rst:658
msgid
""
"Note the placement of ``Py_DECREF(arglist)`` immediately after the call, "
"before the error check! Also note that strictly speaking this code is not "
"complete: :c:func:`Py_BuildValue` may run out of memory, and this should be "
"checked."
msgstr
""
#:
../../extending/extending.rst:662
msgid
""
"You may also call a function with keyword arguments by using :c:func:"
"`PyObject_Call`, which supports arguments and keyword arguments. As in the "
"above example, we use :c:func:`Py_BuildValue` to construct the dictionary. ::"
msgstr
""
#:
../../extending/extending.rst:666
msgid
""
"PyObject *dict;\n"
"...\n"
"dict = Py_BuildValue(
\"
{s:i}
\"
,
\"
name
\"
, val);\n"
"result = PyObject_Call(my_callback, NULL, dict);\n"
"Py_DECREF(dict);\n"
"if (result == NULL)\n"
" return NULL; /* Pass error back */\n"
"/* Here maybe use the result */\n"
"Py_DECREF(result);"
msgstr
""
#:
../../extending/extending.rst:680
msgid
"Extracting Parameters in Extension Functions"
msgstr
""
#:
../../extending/extending.rst:684
View remainder of file in raw view
Back
|
FazBrowse Home
|
New Git URL