-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathextending.html
More file actions
588 lines (549 loc) · 58.2 KB
/
extending.html
File metadata and controls
588 lines (549 loc) · 58.2 KB
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
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="zh_TW">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Extending/Embedding FAQ — Python 3.7.0 說明文件</title>
<link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/underscore.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<script type="text/javascript" src="../_static/translations.js"></script>
<script type="text/javascript" src="../_static/sidebar.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="在 Python 3.7.0 說明文件 中搜尋"
href="../_static/opensearch.xml"/>
<link rel="author" title="關於這些文件" href="../about.html" />
<link rel="index" title="索引" href="../genindex.html" />
<link rel="search" title="搜尋" href="../search.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="next" title="FAQ：在 Windows 使用 Python" href="windows.html" />
<link rel="prev" title="函式庫和擴充功能的常見問題" href="library.html" />
<link rel="shortcut icon" type="image/png" href="../_static/py.png" />
<link rel="canonical" href="https://docs.python.org/3/faq/extending.html" />
<script type="text/javascript" src="../_static/copybutton.js"></script>
<script type="text/javascript" src="../_static/switchers.js"></script>
</head><body>
<div class="related" role="navigation" aria-label="related navigation">
<h3>瀏覽</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">索引</a></li>
<li class="right" >
<a href="../py-modindex.html" title="Python 模組索引"
>模組</a> |</li>
<li class="right" >
<a href="windows.html" title="FAQ：在 Windows 使用 Python"
accesskey="N">下一頁</a> |</li>
<li class="right" >
<a href="library.html" title="函式庫和擴充功能的常見問題"
accesskey="P">上一頁</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> »</li>
<li>
<span class="language_switcher_placeholder">zh_TW</span>
<span class="version_switcher_placeholder">3.7.0</span>
<a href="../index.html">Documentation </a> »
</li>
<li class="nav-item nav-item-1"><a href="index.html" accesskey="U">Python 常見問題</a> »</li>
<li class="right">
<div class="inline-search" style="display: none" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
<script type="text/javascript">$('.inline-search').show(0);</script>
|
</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="section" id="extending-embedding-faq">
<h1><a class="toc-backref" href="#id3">Extending/Embedding FAQ</a><a class="headerlink" href="#extending-embedding-faq" title="本標題的永久連結">¶</a></h1>
<div class="contents topic" id="id1">
<p class="topic-title first">目錄</p>
<ul class="simple">
<li><a class="reference internal" href="#extending-embedding-faq" id="id3">Extending/Embedding FAQ</a><ul>
<li><a class="reference internal" href="#can-i-create-my-own-functions-in-c" id="id4">Can I create my own functions in C?</a></li>
<li><a class="reference internal" href="#id2" id="id5">Can I create my own functions in C++?</a></li>
<li><a class="reference internal" href="#writing-c-is-hard-are-there-any-alternatives" id="id6">Writing C is hard; are there any alternatives?</a></li>
<li><a class="reference internal" href="#how-can-i-execute-arbitrary-python-statements-from-c" id="id7">How can I execute arbitrary Python statements from C?</a></li>
<li><a class="reference internal" href="#how-can-i-evaluate-an-arbitrary-python-expression-from-c" id="id8">How can I evaluate an arbitrary Python expression from C?</a></li>
<li><a class="reference internal" href="#how-do-i-extract-c-values-from-a-python-object" id="id9">How do I extract C values from a Python object?</a></li>
<li><a class="reference internal" href="#how-do-i-use-py-buildvalue-to-create-a-tuple-of-arbitrary-length" id="id10">How do I use Py_BuildValue() to create a tuple of arbitrary length?</a></li>
<li><a class="reference internal" href="#how-do-i-call-an-object-s-method-from-c" id="id11">How do I call an object’s method from C?</a></li>
<li><a class="reference internal" href="#how-do-i-catch-the-output-from-pyerr-print-or-anything-that-prints-to-stdout-stderr" id="id12">How do I catch the output from PyErr_Print() (or anything that prints to stdout/stderr)?</a></li>
<li><a class="reference internal" href="#how-do-i-access-a-module-written-in-python-from-c" id="id13">How do I access a module written in Python from C?</a></li>
<li><a class="reference internal" href="#how-do-i-interface-to-c-objects-from-python" id="id14">How do I interface to C++ objects from Python?</a></li>
<li><a class="reference internal" href="#i-added-a-module-using-the-setup-file-and-the-make-fails-why" id="id15">I added a module using the Setup file and the make fails; why?</a></li>
<li><a class="reference internal" href="#how-do-i-debug-an-extension" id="id16">How do I debug an extension?</a></li>
<li><a class="reference internal" href="#i-want-to-compile-a-python-module-on-my-linux-system-but-some-files-are-missing-why" id="id17">I want to compile a Python module on my Linux system, but some files are missing. Why?</a></li>
<li><a class="reference internal" href="#how-do-i-tell-incomplete-input-from-invalid-input" id="id18">How do I tell 「incomplete input」 from 「invalid input」?</a></li>
<li><a class="reference internal" href="#how-do-i-find-undefined-g-symbols-builtin-new-or-pure-virtual" id="id19">How do I find undefined g++ symbols __builtin_new or __pure_virtual?</a></li>
<li><a class="reference internal" href="#can-i-create-an-object-class-with-some-methods-implemented-in-c-and-others-in-python-e-g-through-inheritance" id="id20">Can I create an object class with some methods implemented in C and others in Python (e.g. through inheritance)?</a></li>
</ul>
</li>
</ul>
</div>
<div class="section" id="can-i-create-my-own-functions-in-c">
<h2><a class="toc-backref" href="#id4">Can I create my own functions in C?</a><a class="headerlink" href="#can-i-create-my-own-functions-in-c" title="本標題的永久連結">¶</a></h2>
<p>Yes, you can create built-in modules containing functions, variables, exceptions
and even new types in C. This is explained in the document
<a class="reference internal" href="../extending/index.html#extending-index"><span class="std std-ref">Extending and Embedding the Python Interpreter</span></a>.</p>
<p>Most intermediate or advanced Python books will also cover this topic.</p>
</div>
<div class="section" id="id2">
<h2><a class="toc-backref" href="#id5">Can I create my own functions in C++?</a><a class="headerlink" href="#id2" title="本標題的永久連結">¶</a></h2>
<p>Yes, using the C compatibility features found in C++. Place <code class="docutils literal notranslate"><span class="pre">extern</span> <span class="pre">"C"</span> <span class="pre">{</span>
<span class="pre">...</span> <span class="pre">}</span></code> around the Python include files and put <code class="docutils literal notranslate"><span class="pre">extern</span> <span class="pre">"C"</span></code> before each
function that is going to be called by the Python interpreter. Global or static
C++ objects with constructors are probably not a good idea.</p>
</div>
<div class="section" id="writing-c-is-hard-are-there-any-alternatives">
<span id="c-wrapper-software"></span><h2><a class="toc-backref" href="#id6">Writing C is hard; are there any alternatives?</a><a class="headerlink" href="#writing-c-is-hard-are-there-any-alternatives" title="本標題的永久連結">¶</a></h2>
<p>There are a number of alternatives to writing your own C extensions, depending
on what you’re trying to do.</p>
<p><a class="reference external" href="http://cython.org">Cython</a> and its relative <a class="reference external" href="https://www.cosc.canterbury.ac.nz/greg.ewing/python/Pyrex/">Pyrex</a> are compilers
that accept a slightly modified form of Python and generate the corresponding
C code. Cython and Pyrex make it possible to write an extension without having
to learn Python’s C API.</p>
<p>If you need to interface to some C or C++ library for which no Python extension
currently exists, you can try wrapping the library’s data types and functions
with a tool such as <a class="reference external" href="http://www.swig.org">SWIG</a>. <a class="reference external" href="https://riverbankcomputing.com/software/sip/intro">SIP</a>, <a class="reference external" href="http://cxx.sourceforge.net/">CXX</a> <a class="reference external" href="http://www.boost.org/libs/python/doc/index.html">Boost</a>, or <a class="reference external" href="https://github.com/scipy/weave">Weave</a> are also
alternatives for wrapping C++ libraries.</p>
</div>
<div class="section" id="how-can-i-execute-arbitrary-python-statements-from-c">
<h2><a class="toc-backref" href="#id7">How can I execute arbitrary Python statements from C?</a><a class="headerlink" href="#how-can-i-execute-arbitrary-python-statements-from-c" title="本標題的永久連結">¶</a></h2>
<p>The highest-level function to do this is <a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_SimpleString" title="PyRun_SimpleString"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_SimpleString()</span></code></a> which takes
a single string argument to be executed in the context of the module
<code class="docutils literal notranslate"><span class="pre">__main__</span></code> and returns <code class="docutils literal notranslate"><span class="pre">0</span></code> for success and <code class="docutils literal notranslate"><span class="pre">-1</span></code> when an exception occurred
(including <code class="docutils literal notranslate"><span class="pre">SyntaxError</span></code>). If you want more control, use
<a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_String" title="PyRun_String"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_String()</span></code></a>; see the source for <a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_SimpleString" title="PyRun_SimpleString"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_SimpleString()</span></code></a> in
<code class="docutils literal notranslate"><span class="pre">Python/pythonrun.c</span></code>.</p>
</div>
<div class="section" id="how-can-i-evaluate-an-arbitrary-python-expression-from-c">
<h2><a class="toc-backref" href="#id8">How can I evaluate an arbitrary Python expression from C?</a><a class="headerlink" href="#how-can-i-evaluate-an-arbitrary-python-expression-from-c" title="本標題的永久連結">¶</a></h2>
<p>Call the function <a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_String" title="PyRun_String"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_String()</span></code></a> from the previous question with the
start symbol <a class="reference internal" href="../c-api/veryhigh.html#c.Py_eval_input" title="Py_eval_input"><code class="xref c c-data docutils literal notranslate"><span class="pre">Py_eval_input</span></code></a>; it parses an expression, evaluates it and
returns its value.</p>
</div>
<div class="section" id="how-do-i-extract-c-values-from-a-python-object">
<h2><a class="toc-backref" href="#id9">How do I extract C values from a Python object?</a><a class="headerlink" href="#how-do-i-extract-c-values-from-a-python-object" title="本標題的永久連結">¶</a></h2>
<p>That depends on the object’s type. If it’s a tuple, <a class="reference internal" href="../c-api/tuple.html#c.PyTuple_Size" title="PyTuple_Size"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyTuple_Size()</span></code></a>
returns its length and <a class="reference internal" href="../c-api/tuple.html#c.PyTuple_GetItem" title="PyTuple_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyTuple_GetItem()</span></code></a> returns the item at a specified
index. Lists have similar functions, <code class="xref c c-func docutils literal notranslate"><span class="pre">PyListSize()</span></code> and
<a class="reference internal" href="../c-api/list.html#c.PyList_GetItem" title="PyList_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyList_GetItem()</span></code></a>.</p>
<p>For bytes, <a class="reference internal" href="../c-api/bytes.html#c.PyBytes_Size" title="PyBytes_Size"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyBytes_Size()</span></code></a> returns its length and
<a class="reference internal" href="../c-api/bytes.html#c.PyBytes_AsStringAndSize" title="PyBytes_AsStringAndSize"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyBytes_AsStringAndSize()</span></code></a> provides a pointer to its value and its
length. Note that Python bytes objects may contain null bytes so C’s
<code class="xref c c-func docutils literal notranslate"><span class="pre">strlen()</span></code> should not be used.</p>
<p>To test the type of an object, first make sure it isn’t <em>NULL</em>, and then use
<a class="reference internal" href="../c-api/bytes.html#c.PyBytes_Check" title="PyBytes_Check"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyBytes_Check()</span></code></a>, <a class="reference internal" href="../c-api/tuple.html#c.PyTuple_Check" title="PyTuple_Check"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyTuple_Check()</span></code></a>, <a class="reference internal" href="../c-api/list.html#c.PyList_Check" title="PyList_Check"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyList_Check()</span></code></a>, etc.</p>
<p>There is also a high-level API to Python objects which is provided by the
so-called 『abstract』 interface – read <code class="docutils literal notranslate"><span class="pre">Include/abstract.h</span></code> for further
details. It allows interfacing with any kind of Python sequence using calls
like <a class="reference internal" href="../c-api/sequence.html#c.PySequence_Length" title="PySequence_Length"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySequence_Length()</span></code></a>, <a class="reference internal" href="../c-api/sequence.html#c.PySequence_GetItem" title="PySequence_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySequence_GetItem()</span></code></a>, etc. as well
as many other useful protocols such as numbers (<a class="reference internal" href="../c-api/number.html#c.PyNumber_Index" title="PyNumber_Index"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyNumber_Index()</span></code></a> et
al.) and mappings in the PyMapping APIs.</p>
</div>
<div class="section" id="how-do-i-use-py-buildvalue-to-create-a-tuple-of-arbitrary-length">
<h2><a class="toc-backref" href="#id10">How do I use Py_BuildValue() to create a tuple of arbitrary length?</a><a class="headerlink" href="#how-do-i-use-py-buildvalue-to-create-a-tuple-of-arbitrary-length" title="本標題的永久連結">¶</a></h2>
<p>You can’t. Use <a class="reference internal" href="../c-api/tuple.html#c.PyTuple_Pack" title="PyTuple_Pack"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyTuple_Pack()</span></code></a> instead.</p>
</div>
<div class="section" id="how-do-i-call-an-object-s-method-from-c">
<h2><a class="toc-backref" href="#id11">How do I call an object’s method from C?</a><a class="headerlink" href="#how-do-i-call-an-object-s-method-from-c" title="本標題的永久連結">¶</a></h2>
<p>The <a class="reference internal" href="../c-api/object.html#c.PyObject_CallMethod" title="PyObject_CallMethod"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_CallMethod()</span></code></a> function can be used to call an arbitrary
method of an object. The parameters are the object, the name of the method to
call, a format string like that used with <a class="reference internal" href="../c-api/arg.html#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a>, and the
argument values:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">PyObject</span> <span class="o">*</span>
<span class="nf">PyObject_CallMethod</span><span class="p">(</span><span class="n">PyObject</span> <span class="o">*</span><span class="n">object</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">method_name</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">arg_format</span><span class="p">,</span> <span class="p">...);</span>
</pre></div>
</div>
<p>This works for any object that has methods – whether built-in or user-defined.
You are responsible for eventually <a class="reference internal" href="../c-api/refcounting.html#c.Py_DECREF" title="Py_DECREF"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_DECREF()</span></code></a>』ing the return value.</p>
<p>To call, e.g., a file object’s 「seek」 method with arguments 10, 0 (assuming the
file object pointer is 「f」):</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">res</span> <span class="o">=</span> <span class="n">PyObject_CallMethod</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="s">"seek"</span><span class="p">,</span> <span class="s">"(ii)"</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="mi">0</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="n">res</span> <span class="o">==</span> <span class="nb">NULL</span><span class="p">)</span> <span class="p">{</span>
<span class="p">...</span> <span class="n">an</span> <span class="n">exception</span> <span class="n">occurred</span> <span class="p">...</span>
<span class="p">}</span>
<span class="k">else</span> <span class="p">{</span>
<span class="n">Py_DECREF</span><span class="p">(</span><span class="n">res</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Note that since <a class="reference internal" href="../c-api/object.html#c.PyObject_CallObject" title="PyObject_CallObject"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_CallObject()</span></code></a> <em>always</em> wants a tuple for the
argument list, to call a function without arguments, pass 「()」 for the format,
and to call a function with one argument, surround the argument in parentheses,
e.g. 「(i)」.</p>
</div>
<div class="section" id="how-do-i-catch-the-output-from-pyerr-print-or-anything-that-prints-to-stdout-stderr">
<h2><a class="toc-backref" href="#id12">How do I catch the output from PyErr_Print() (or anything that prints to stdout/stderr)?</a><a class="headerlink" href="#how-do-i-catch-the-output-from-pyerr-print-or-anything-that-prints-to-stdout-stderr" title="本標題的永久連結">¶</a></h2>
<p>In Python code, define an object that supports the <code class="docutils literal notranslate"><span class="pre">write()</span></code> method. Assign
this object to <a class="reference internal" href="../library/sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a> and <a class="reference internal" href="../library/sys.html#sys.stderr" title="sys.stderr"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stderr</span></code></a>. Call print_error, or
just allow the standard traceback mechanism to work. Then, the output will go
wherever your <code class="docutils literal notranslate"><span class="pre">write()</span></code> method sends it.</p>
<p>The easiest way to do this is to use the <a class="reference internal" href="../library/io.html#io.StringIO" title="io.StringIO"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.StringIO</span></code></a> class:</p>
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">io</span><span class="o">,</span> <span class="nn">sys</span>
<span class="gp">>>> </span><span class="n">sys</span><span class="o">.</span><span class="n">stdout</span> <span class="o">=</span> <span class="n">io</span><span class="o">.</span><span class="n">StringIO</span><span class="p">()</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="s1">'foo'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="s1">'hello world!'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">sys</span><span class="o">.</span><span class="n">stderr</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">stdout</span><span class="o">.</span><span class="n">getvalue</span><span class="p">())</span>
<span class="go">foo</span>
<span class="go">hello world!</span>
</pre></div>
</div>
<p>A custom object to do the same would look like this:</p>
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">io</span><span class="o">,</span> <span class="nn">sys</span>
<span class="gp">>>> </span><span class="k">class</span> <span class="nc">StdoutCatcher</span><span class="p">(</span><span class="n">io</span><span class="o">.</span><span class="n">TextIOBase</span><span class="p">):</span>
<span class="gp">... </span> <span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="gp">... </span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="p">[]</span>
<span class="gp">... </span> <span class="k">def</span> <span class="nf">write</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">stuff</span><span class="p">):</span>
<span class="gp">... </span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">stuff</span><span class="p">)</span>
<span class="gp">...</span>
<span class="gp">>>> </span><span class="kn">import</span> <span class="nn">sys</span>
<span class="gp">>>> </span><span class="n">sys</span><span class="o">.</span><span class="n">stdout</span> <span class="o">=</span> <span class="n">StdoutCatcher</span><span class="p">()</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="s1">'foo'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="s1">'hello world!'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">sys</span><span class="o">.</span><span class="n">stderr</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s1">''</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">stdout</span><span class="o">.</span><span class="n">data</span><span class="p">))</span>
<span class="go">foo</span>
<span class="go">hello world!</span>
</pre></div>
</div>
</div>
<div class="section" id="how-do-i-access-a-module-written-in-python-from-c">
<h2><a class="toc-backref" href="#id13">How do I access a module written in Python from C?</a><a class="headerlink" href="#how-do-i-access-a-module-written-in-python-from-c" title="本標題的永久連結">¶</a></h2>
<p>You can get a pointer to the module object as follows:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">module</span> <span class="o">=</span> <span class="n">PyImport_ImportModule</span><span class="p">(</span><span class="s">"<modulename>"</span><span class="p">);</span>
</pre></div>
</div>
<p>If the module hasn’t been imported yet (i.e. it is not yet present in
<a class="reference internal" href="../library/sys.html#sys.modules" title="sys.modules"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.modules</span></code></a>), this initializes the module; otherwise it simply returns
the value of <code class="docutils literal notranslate"><span class="pre">sys.modules["<modulename>"]</span></code>. Note that it doesn’t enter the
module into any namespace – it only ensures it has been initialized and is
stored in <a class="reference internal" href="../library/sys.html#sys.modules" title="sys.modules"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.modules</span></code></a>.</p>
<p>You can then access the module’s attributes (i.e. any name defined in the
module) as follows:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">attr</span> <span class="o">=</span> <span class="n">PyObject_GetAttrString</span><span class="p">(</span><span class="n">module</span><span class="p">,</span> <span class="s">"<attrname>"</span><span class="p">);</span>
</pre></div>
</div>
<p>Calling <a class="reference internal" href="../c-api/object.html#c.PyObject_SetAttrString" title="PyObject_SetAttrString"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_SetAttrString()</span></code></a> to assign to variables in the module
also works.</p>
</div>
<div class="section" id="how-do-i-interface-to-c-objects-from-python">
<h2><a class="toc-backref" href="#id14">How do I interface to C++ objects from Python?</a><a class="headerlink" href="#how-do-i-interface-to-c-objects-from-python" title="本標題的永久連結">¶</a></h2>
<p>Depending on your requirements, there are many approaches. To do this manually,
begin by reading <a class="reference internal" href="../extending/index.html#extending-index"><span class="std std-ref">the 「Extending and Embedding」 document</span></a>. Realize that for the Python run-time system, there isn’t a
whole lot of difference between C and C++ – so the strategy of building a new
Python type around a C structure (pointer) type will also work for C++ objects.</p>
<p>For C++ libraries, see <a class="reference internal" href="#c-wrapper-software"><span class="std std-ref">Writing C is hard; are there any alternatives?</span></a>.</p>
</div>
<div class="section" id="i-added-a-module-using-the-setup-file-and-the-make-fails-why">
<h2><a class="toc-backref" href="#id15">I added a module using the Setup file and the make fails; why?</a><a class="headerlink" href="#i-added-a-module-using-the-setup-file-and-the-make-fails-why" title="本標題的永久連結">¶</a></h2>
<p>Setup must end in a newline, if there is no newline there, the build process
fails. (Fixing this requires some ugly shell script hackery, and this bug is so
minor that it doesn’t seem worth the effort.)</p>
</div>
<div class="section" id="how-do-i-debug-an-extension">
<h2><a class="toc-backref" href="#id16">How do I debug an extension?</a><a class="headerlink" href="#how-do-i-debug-an-extension" title="本標題的永久連結">¶</a></h2>
<p>When using GDB with dynamically loaded extensions, you can’t set a breakpoint in
your extension until your extension is loaded.</p>
<p>In your <code class="docutils literal notranslate"><span class="pre">.gdbinit</span></code> file (or interactively), add the command:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>br _PyImport_LoadDynamicModule
</pre></div>
</div>
<p>Then, when you run GDB:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> gdb /local/bin/python
<span class="go">gdb) run myscript.py</span>
<span class="go">gdb) continue # repeat until your extension is loaded</span>
<span class="go">gdb) finish # so that your extension is loaded</span>
<span class="go">gdb) br myfunction.c:50</span>
<span class="go">gdb) continue</span>
</pre></div>
</div>
</div>
<div class="section" id="i-want-to-compile-a-python-module-on-my-linux-system-but-some-files-are-missing-why">
<h2><a class="toc-backref" href="#id17">I want to compile a Python module on my Linux system, but some files are missing. Why?</a><a class="headerlink" href="#i-want-to-compile-a-python-module-on-my-linux-system-but-some-files-are-missing-why" title="本標題的永久連結">¶</a></h2>
<p>Most packaged versions of Python don’t include the
<code class="file docutils literal notranslate"><span class="pre">/usr/lib/python2.</span><em><span class="pre">x</span></em><span class="pre">/config/</span></code> directory, which contains various files
required for compiling Python extensions.</p>
<p>For Red Hat, install the python-devel RPM to get the necessary files.</p>
<p>For Debian, run <code class="docutils literal notranslate"><span class="pre">apt-get</span> <span class="pre">install</span> <span class="pre">python-dev</span></code>.</p>
</div>
<div class="section" id="how-do-i-tell-incomplete-input-from-invalid-input">
<h2><a class="toc-backref" href="#id18">How do I tell 「incomplete input」 from 「invalid input」?</a><a class="headerlink" href="#how-do-i-tell-incomplete-input-from-invalid-input" title="本標題的永久連結">¶</a></h2>
<p>Sometimes you want to emulate the Python interactive interpreter’s behavior,
where it gives you a continuation prompt when the input is incomplete (e.g. you
typed the start of an 「if」 statement or you didn’t close your parentheses or
triple string quotes), but it gives you a syntax error message immediately when
the input is invalid.</p>
<p>In Python you can use the <a class="reference internal" href="../library/codeop.html#module-codeop" title="codeop: Compile (possibly incomplete) Python code."><code class="xref py py-mod docutils literal notranslate"><span class="pre">codeop</span></code></a> module, which approximates the parser’s
behavior sufficiently. IDLE uses this, for example.</p>
<p>The easiest way to do it in C is to call <a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_InteractiveLoop" title="PyRun_InteractiveLoop"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_InteractiveLoop()</span></code></a> (perhaps
in a separate thread) and let the Python interpreter handle the input for
you. You can also set the <a class="reference internal" href="../c-api/veryhigh.html#c.PyOS_ReadlineFunctionPointer" title="PyOS_ReadlineFunctionPointer"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyOS_ReadlineFunctionPointer()</span></code></a> to point at your
custom input function. See <code class="docutils literal notranslate"><span class="pre">Modules/readline.c</span></code> and <code class="docutils literal notranslate"><span class="pre">Parser/myreadline.c</span></code>
for more hints.</p>
<p>However sometimes you have to run the embedded Python interpreter in the same
thread as your rest application and you can’t allow the
<a class="reference internal" href="../c-api/veryhigh.html#c.PyRun_InteractiveLoop" title="PyRun_InteractiveLoop"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyRun_InteractiveLoop()</span></code></a> to stop while waiting for user input. The one
solution then is to call <code class="xref c c-func docutils literal notranslate"><span class="pre">PyParser_ParseString()</span></code> and test for <code class="docutils literal notranslate"><span class="pre">e.error</span></code>
equal to <code class="docutils literal notranslate"><span class="pre">E_EOF</span></code>, which means the input is incomplete). Here’s a sample code
fragment, untested, inspired by code from Alex Farber:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span> <span class="cpf"><Python.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><node.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><errcode.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><grammar.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><parsetok.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><compile.h></span><span class="cp"></span>
<span class="kt">int</span> <span class="nf">testcomplete</span><span class="p">(</span><span class="kt">char</span> <span class="o">*</span><span class="n">code</span><span class="p">)</span>
<span class="cm">/* code should end in \n */</span>
<span class="cm">/* return -1 for error, 0 for incomplete, 1 for complete */</span>
<span class="p">{</span>
<span class="n">node</span> <span class="o">*</span><span class="n">n</span><span class="p">;</span>
<span class="n">perrdetail</span> <span class="n">e</span><span class="p">;</span>
<span class="n">n</span> <span class="o">=</span> <span class="n">PyParser_ParseString</span><span class="p">(</span><span class="n">code</span><span class="p">,</span> <span class="o">&</span><span class="n">_PyParser_Grammar</span><span class="p">,</span>
<span class="n">Py_file_input</span><span class="p">,</span> <span class="o">&</span><span class="n">e</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="n">n</span> <span class="o">==</span> <span class="nb">NULL</span><span class="p">)</span> <span class="p">{</span>
<span class="k">if</span> <span class="p">(</span><span class="n">e</span><span class="p">.</span><span class="n">error</span> <span class="o">==</span> <span class="n">E_EOF</span><span class="p">)</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">PyNode_Free</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
<span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Another solution is trying to compile the received string with
<a class="reference internal" href="../c-api/veryhigh.html#c.Py_CompileString" title="Py_CompileString"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_CompileString()</span></code></a>. If it compiles without errors, try to execute the
returned code object by calling <a class="reference internal" href="../c-api/veryhigh.html#c.PyEval_EvalCode" title="PyEval_EvalCode"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyEval_EvalCode()</span></code></a>. Otherwise save the
input for later. If the compilation fails, find out if it’s an error or just
more input is required - by extracting the message string from the exception
tuple and comparing it to the string 「unexpected EOF while parsing」. Here is a
complete example using the GNU readline library (you may want to ignore
<strong>SIGINT</strong> while calling readline()):</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span> <span class="cpf"><stdio.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><readline.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><Python.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><object.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><compile.h></span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf"><eval.h></span><span class="cp"></span>
<span class="kt">int</span> <span class="nf">main</span> <span class="p">(</span><span class="kt">int</span> <span class="n">argc</span><span class="p">,</span> <span class="kt">char</span><span class="o">*</span> <span class="n">argv</span><span class="p">[])</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">i</span><span class="p">,</span> <span class="n">j</span><span class="p">,</span> <span class="n">done</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span class="cm">/* lengths of line, code */</span>
<span class="kt">char</span> <span class="n">ps1</span><span class="p">[]</span> <span class="o">=</span> <span class="s">">>> "</span><span class="p">;</span>
<span class="kt">char</span> <span class="n">ps2</span><span class="p">[]</span> <span class="o">=</span> <span class="s">"... "</span><span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">prompt</span> <span class="o">=</span> <span class="n">ps1</span><span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">msg</span><span class="p">,</span> <span class="o">*</span><span class="n">line</span><span class="p">,</span> <span class="o">*</span><span class="n">code</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">PyObject</span> <span class="o">*</span><span class="n">src</span><span class="p">,</span> <span class="o">*</span><span class="n">glb</span><span class="p">,</span> <span class="o">*</span><span class="n">loc</span><span class="p">;</span>
<span class="n">PyObject</span> <span class="o">*</span><span class="n">exc</span><span class="p">,</span> <span class="o">*</span><span class="n">val</span><span class="p">,</span> <span class="o">*</span><span class="n">trb</span><span class="p">,</span> <span class="o">*</span><span class="n">obj</span><span class="p">,</span> <span class="o">*</span><span class="n">dum</span><span class="p">;</span>
<span class="n">Py_Initialize</span> <span class="p">();</span>
<span class="n">loc</span> <span class="o">=</span> <span class="n">PyDict_New</span> <span class="p">();</span>
<span class="n">glb</span> <span class="o">=</span> <span class="n">PyDict_New</span> <span class="p">();</span>
<span class="n">PyDict_SetItemString</span> <span class="p">(</span><span class="n">glb</span><span class="p">,</span> <span class="s">"__builtins__"</span><span class="p">,</span> <span class="n">PyEval_GetBuiltins</span> <span class="p">());</span>
<span class="k">while</span> <span class="p">(</span><span class="o">!</span><span class="n">done</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">line</span> <span class="o">=</span> <span class="n">readline</span> <span class="p">(</span><span class="n">prompt</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="nb">NULL</span> <span class="o">==</span> <span class="n">line</span><span class="p">)</span> <span class="cm">/* Ctrl-D pressed */</span>
<span class="p">{</span>
<span class="n">done</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">else</span>
<span class="p">{</span>
<span class="n">i</span> <span class="o">=</span> <span class="n">strlen</span> <span class="p">(</span><span class="n">line</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="n">i</span> <span class="o">></span> <span class="mi">0</span><span class="p">)</span>
<span class="n">add_history</span> <span class="p">(</span><span class="n">line</span><span class="p">);</span> <span class="cm">/* save non-empty lines */</span>
<span class="k">if</span> <span class="p">(</span><span class="nb">NULL</span> <span class="o">==</span> <span class="n">code</span><span class="p">)</span> <span class="cm">/* nothing in code yet */</span>
<span class="n">j</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
<span class="k">else</span>
<span class="n">j</span> <span class="o">=</span> <span class="n">strlen</span> <span class="p">(</span><span class="n">code</span><span class="p">);</span>
<span class="n">code</span> <span class="o">=</span> <span class="n">realloc</span> <span class="p">(</span><span class="n">code</span><span class="p">,</span> <span class="n">i</span> <span class="o">+</span> <span class="n">j</span> <span class="o">+</span> <span class="mi">2</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="nb">NULL</span> <span class="o">==</span> <span class="n">code</span><span class="p">)</span> <span class="cm">/* out of memory */</span>
<span class="n">exit</span> <span class="p">(</span><span class="mi">1</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="mi">0</span> <span class="o">==</span> <span class="n">j</span><span class="p">)</span> <span class="cm">/* code was empty, so */</span>
<span class="n">code</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="sc">'\0'</span><span class="p">;</span> <span class="cm">/* keep strncat happy */</span>
<span class="n">strncat</span> <span class="p">(</span><span class="n">code</span><span class="p">,</span> <span class="n">line</span><span class="p">,</span> <span class="n">i</span><span class="p">);</span> <span class="cm">/* append line to code */</span>
<span class="n">code</span><span class="p">[</span><span class="n">i</span> <span class="o">+</span> <span class="n">j</span><span class="p">]</span> <span class="o">=</span> <span class="sc">'\n'</span><span class="p">;</span> <span class="cm">/* append '\n' to code */</span>
<span class="n">code</span><span class="p">[</span><span class="n">i</span> <span class="o">+</span> <span class="n">j</span> <span class="o">+</span> <span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="sc">'\0'</span><span class="p">;</span>
<span class="n">src</span> <span class="o">=</span> <span class="n">Py_CompileString</span> <span class="p">(</span><span class="n">code</span><span class="p">,</span> <span class="s">"<stdin>"</span><span class="p">,</span> <span class="n">Py_single_input</span><span class="p">);</span>
<span class="k">if</span> <span class="p">(</span><span class="nb">NULL</span> <span class="o">!=</span> <span class="n">src</span><span class="p">)</span> <span class="cm">/* compiled just fine - */</span>
<span class="p">{</span>
<span class="k">if</span> <span class="p">(</span><span class="n">ps1</span> <span class="o">==</span> <span class="n">prompt</span> <span class="o">||</span> <span class="cm">/* ">>> " or */</span>
<span class="sc">'\n'</span> <span class="o">==</span> <span class="n">code</span><span class="p">[</span><span class="n">i</span> <span class="o">+</span> <span class="n">j</span> <span class="o">-</span> <span class="mi">1</span><span class="p">])</span> <span class="cm">/* "... " and double '\n' */</span>
<span class="p">{</span> <span class="cm">/* so execute it */</span>
<span class="n">dum</span> <span class="o">=</span> <span class="n">PyEval_EvalCode</span> <span class="p">(</span><span class="n">src</span><span class="p">,</span> <span class="n">glb</span><span class="p">,</span> <span class="n">loc</span><span class="p">);</span>
<span class="n">Py_XDECREF</span> <span class="p">(</span><span class="n">dum</span><span class="p">);</span>
<span class="n">Py_XDECREF</span> <span class="p">(</span><span class="n">src</span><span class="p">);</span>
<span class="n">free</span> <span class="p">(</span><span class="n">code</span><span class="p">);</span>
<span class="n">code</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="k">if</span> <span class="p">(</span><span class="n">PyErr_Occurred</span> <span class="p">())</span>
<span class="n">PyErr_Print</span> <span class="p">();</span>
<span class="n">prompt</span> <span class="o">=</span> <span class="n">ps1</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span> <span class="cm">/* syntax error or E_EOF? */</span>
<span class="k">else</span> <span class="k">if</span> <span class="p">(</span><span class="n">PyErr_ExceptionMatches</span> <span class="p">(</span><span class="n">PyExc_SyntaxError</span><span class="p">))</span>
<span class="p">{</span>
<span class="n">PyErr_Fetch</span> <span class="p">(</span><span class="o">&</span><span class="n">exc</span><span class="p">,</span> <span class="o">&</span><span class="n">val</span><span class="p">,</span> <span class="o">&</span><span class="n">trb</span><span class="p">);</span> <span class="cm">/* clears exception! */</span>
<span class="k">if</span> <span class="p">(</span><span class="n">PyArg_ParseTuple</span> <span class="p">(</span><span class="n">val</span><span class="p">,</span> <span class="s">"sO"</span><span class="p">,</span> <span class="o">&</span><span class="n">msg</span><span class="p">,</span> <span class="o">&</span><span class="n">obj</span><span class="p">)</span> <span class="o">&&</span>
<span class="o">!</span><span class="n">strcmp</span> <span class="p">(</span><span class="n">msg</span><span class="p">,</span> <span class="s">"unexpected EOF while parsing"</span><span class="p">))</span> <span class="cm">/* E_EOF */</span>
<span class="p">{</span>
<span class="n">Py_XDECREF</span> <span class="p">(</span><span class="n">exc</span><span class="p">);</span>
<span class="n">Py_XDECREF</span> <span class="p">(</span><span class="n">val</span><span class="p">);</span>
<span class="n">Py_XDECREF</span> <span class="p">(</span><span class="n">trb</span><span class="p">);</span>
<span class="n">prompt</span> <span class="o">=</span> <span class="n">ps2</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">else</span> <span class="cm">/* some other syntax error */</span>
<span class="p">{</span>
<span class="n">PyErr_Restore</span> <span class="p">(</span><span class="n">exc</span><span class="p">,</span> <span class="n">val</span><span class="p">,</span> <span class="n">trb</span><span class="p">);</span>
<span class="n">PyErr_Print</span> <span class="p">();</span>
<span class="n">free</span> <span class="p">(</span><span class="n">code</span><span class="p">);</span>
<span class="n">code</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">prompt</span> <span class="o">=</span> <span class="n">ps1</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">else</span> <span class="cm">/* some non-syntax error */</span>
<span class="p">{</span>
<span class="n">PyErr_Print</span> <span class="p">();</span>
<span class="n">free</span> <span class="p">(</span><span class="n">code</span><span class="p">);</span>
<span class="n">code</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">prompt</span> <span class="o">=</span> <span class="n">ps1</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">free</span> <span class="p">(</span><span class="n">line</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="n">Py_XDECREF</span><span class="p">(</span><span class="n">glb</span><span class="p">);</span>
<span class="n">Py_XDECREF</span><span class="p">(</span><span class="n">loc</span><span class="p">);</span>
<span class="n">Py_Finalize</span><span class="p">();</span>
<span class="n">exit</span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="how-do-i-find-undefined-g-symbols-builtin-new-or-pure-virtual">
<h2><a class="toc-backref" href="#id19">How do I find undefined g++ symbols __builtin_new or __pure_virtual?</a><a class="headerlink" href="#how-do-i-find-undefined-g-symbols-builtin-new-or-pure-virtual" title="本標題的永久連結">¶</a></h2>
<p>To dynamically load g++ extension modules, you must recompile Python, relink it
using g++ (change LINKCC in the Python Modules Makefile), and link your
extension module using g++ (e.g., <code class="docutils literal notranslate"><span class="pre">g++</span> <span class="pre">-shared</span> <span class="pre">-o</span> <span class="pre">mymodule.so</span> <span class="pre">mymodule.o</span></code>).</p>
</div>
<div class="section" id="can-i-create-an-object-class-with-some-methods-implemented-in-c-and-others-in-python-e-g-through-inheritance">
<h2><a class="toc-backref" href="#id20">Can I create an object class with some methods implemented in C and others in Python (e.g. through inheritance)?</a><a class="headerlink" href="#can-i-create-an-object-class-with-some-methods-implemented-in-c-and-others-in-python-e-g-through-inheritance" title="本標題的永久連結">¶</a></h2>
<p>Yes, you can inherit from built-in classes such as <a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>, <a class="reference internal" href="../library/stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a>,
<a class="reference internal" href="../library/stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a>, etc.</p>
<p>The Boost Python Library (BPL, <a class="reference external" href="http://www.boost.org/libs/python/doc/index.html">http://www.boost.org/libs/python/doc/index.html</a>)
provides a way of doing this from C++ (i.e. you can inherit from an extension
class written in C++ using the BPL).</p>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<h3><a href="../contents.html">目錄</a></h3>
<ul>
<li><a class="reference internal" href="#">Extending/Embedding FAQ</a><ul>
<li><a class="reference internal" href="#can-i-create-my-own-functions-in-c">Can I create my own functions in C?</a></li>
<li><a class="reference internal" href="#id2">Can I create my own functions in C++?</a></li>
<li><a class="reference internal" href="#writing-c-is-hard-are-there-any-alternatives">Writing C is hard; are there any alternatives?</a></li>
<li><a class="reference internal" href="#how-can-i-execute-arbitrary-python-statements-from-c">How can I execute arbitrary Python statements from C?</a></li>
<li><a class="reference internal" href="#how-can-i-evaluate-an-arbitrary-python-expression-from-c">How can I evaluate an arbitrary Python expression from C?</a></li>
<li><a class="reference internal" href="#how-do-i-extract-c-values-from-a-python-object">How do I extract C values from a Python object?</a></li>
<li><a class="reference internal" href="#how-do-i-use-py-buildvalue-to-create-a-tuple-of-arbitrary-length">How do I use Py_BuildValue() to create a tuple of arbitrary length?</a></li>
<li><a class="reference internal" href="#how-do-i-call-an-object-s-method-from-c">How do I call an object’s method from C?</a></li>
<li><a class="reference internal" href="#how-do-i-catch-the-output-from-pyerr-print-or-anything-that-prints-to-stdout-stderr">How do I catch the output from PyErr_Print() (or anything that prints to stdout/stderr)?</a></li>
<li><a class="reference internal" href="#how-do-i-access-a-module-written-in-python-from-c">How do I access a module written in Python from C?</a></li>
<li><a class="reference internal" href="#how-do-i-interface-to-c-objects-from-python">How do I interface to C++ objects from Python?</a></li>
<li><a class="reference internal" href="#i-added-a-module-using-the-setup-file-and-the-make-fails-why">I added a module using the Setup file and the make fails; why?</a></li>
<li><a class="reference internal" href="#how-do-i-debug-an-extension">How do I debug an extension?</a></li>
<li><a class="reference internal" href="#i-want-to-compile-a-python-module-on-my-linux-system-but-some-files-are-missing-why">I want to compile a Python module on my Linux system, but some files are missing. Why?</a></li>
<li><a class="reference internal" href="#how-do-i-tell-incomplete-input-from-invalid-input">How do I tell 「incomplete input」 from 「invalid input」?</a></li>
<li><a class="reference internal" href="#how-do-i-find-undefined-g-symbols-builtin-new-or-pure-virtual">How do I find undefined g++ symbols __builtin_new or __pure_virtual?</a></li>
<li><a class="reference internal" href="#can-i-create-an-object-class-with-some-methods-implemented-in-c-and-others-in-python-e-g-through-inheritance">Can I create an object class with some methods implemented in C and others in Python (e.g. through inheritance)?</a></li>
</ul>
</li>
</ul>
<h4>上個主題</h4>
<p class="topless"><a href="library.html"
title="上一章">函式庫和擴充功能的常見問題</a></p>
<h4>下個主題</h4>
<p class="topless"><a href="windows.html"
title="下一章">FAQ：在 Windows 使用 Python</a></p>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../bugs.html">Report a Bug</a></li>
<li>
<a href="https://github.com/python/cpython/blob/3.7/Doc/faq/extending.rst"
rel="nofollow">Show Source
</a>
</li>
</ul>
</div>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related" role="navigation" aria-label="related navigation">
<h3>瀏覽</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
>索引</a></li>
<li class="right" >
<a href="../py-modindex.html" title="Python 模組索引"
>模組</a> |</li>
<li class="right" >
<a href="windows.html" title="FAQ：在 Windows 使用 Python"
>下一頁</a> |</li>
<li class="right" >
<a href="library.html" title="函式庫和擴充功能的常見問題"
>上一頁</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> »</li>
<li>
<span class="language_switcher_placeholder">zh_TW</span>
<span class="version_switcher_placeholder">3.7.0</span>
<a href="../index.html">Documentation </a> »
</li>
<li class="nav-item nav-item-1"><a href="index.html" >Python 常見問題</a> »</li>
<li class="right">
<div class="inline-search" style="display: none" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
<script type="text/javascript">$('.inline-search').show(0);</script>
|
</li>
</ul>
</div>
<div class="footer">
© <a href="../copyright.html">Copyright</a> 2001-2018, Python Software Foundation.
<br />
The Python Software Foundation is a non-profit corporation.
<a href="https://www.python.org/psf/donations/">Please donate.</a>
<br />
Last updated on 8月 22, 2018.
<a href="../bugs.html">Found a bug</a>?
<br />
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.7.
</div>
</body>
</html>