@@ -203,31 +203,42 @@ function usually raises :c:data:`PyExc_TypeError`. If you have an argument whos
203203value must be in a particular range or must satisfy other conditions,
204204:c:data: `PyExc_ValueError ` is appropriate.
205205
206- You can also define a new exception that is unique to your module. For this, you
207- usually declare a static object variable at the beginning of your file::
206+ You can also define a new exception that is unique to your module.
207+ For this, you can declare a static global object variable at the beginning
208+ of the file::
208209
209210 static PyObject *SpamError;
210211
211- and initialize it in your module's initialization function ( :c:func: ` !PyInit_spam `)
212- with an exception object ::
212+ and initialize it with an exception object in the module's
213+ :c:data: ` Py_mod_exec ` function ( :c:func: ` !spam_module_exec `) ::
213214
214- PyMODINIT_FUNC
215- PyInit_spam(void )
215+ static int
216+ spam_module_exec(PyObject *m )
216217 {
217- PyObject *m;
218-
219- m = PyModule_Create(&spammodule);
220- if (m == NULL)
221- return NULL;
222-
223218 SpamError = PyErr_NewException("spam.error", NULL, NULL);
224- if (PyModule_AddObjectRef(m, "error", SpamError) < 0) {
225- Py_CLEAR(SpamError);
226- Py_DECREF(m);
227- return NULL;
219+ if (PyModule_AddObjectRef(m, "SpamError", SpamError) < 0) {
220+ return -1;
228221 }
229222
230- return m;
223+ return 0;
224+ }
225+
226+ static PyModuleDef_Slot spam_module_slots[] = {
227+ {Py_mod_exec, spam_module_exec},
228+ {0, NULL}
229+ };
230+
231+ static struct PyModuleDef spam_module = {
232+ .m_base = PyModuleDef_HEAD_INIT,
233+ .m_name = "spam",
234+ .m_size = 0, // non-negative
235+ .m_slots = spam_module_slots,
236+ };
237+
238+ PyMODINIT_FUNC
239+ PyInit_spam(void)
240+ {
241+ return PyModuleDef_Init(&spam_module);
231242 }
232243
233244Note that the Python name for the exception object is :exc: `!spam.error `. The
@@ -318,7 +329,7 @@ The Module's Method Table and Initialization Function
318329I promised to show how :c:func: `!spam_system ` is called from Python programs.
319330First, we need to list its name and address in a "method table"::
320331
321- static PyMethodDef SpamMethods [] = {
332+ static PyMethodDef spam_methods [] = {
322333 ...
323334 {"system", spam_system, METH_VARARGS,
324335 "Execute a shell command."},
@@ -343,13 +354,10 @@ function.
343354
344355The method table must be referenced in the module definition structure::
345356
346- static struct PyModuleDef spammodule = {
347- PyModuleDef_HEAD_INIT,
348- "spam", /* name of module */
349- spam_doc, /* module documentation, may be NULL */
350- -1, /* size of per-interpreter state of the module,
351- or -1 if the module keeps state in global variables. */
352- SpamMethods
357+ static struct PyModuleDef spam_module = {
358+ ...
359+ .m_methods = spam_methods,
360+ ...
353361 };
354362
355363This structure, in turn, must be passed to the interpreter in the module's
@@ -360,23 +368,17 @@ only non-\ ``static`` item defined in the module file::
360368 PyMODINIT_FUNC
361369 PyInit_spam(void)
362370 {
363- return PyModule_Create(&spammodule );
371+ return PyModuleDef_Init(&spam_module );
364372 }
365373
366374Note that :c:macro: `PyMODINIT_FUNC ` declares the function as ``PyObject * `` return type,
367375declares any special linkage declarations required by the platform, and for C++
368376declares the function as ``extern "C" ``.
369377
370- When the Python program imports module :mod: `!spam ` for the first time,
371- :c:func: `!PyInit_spam ` is called. (See below for comments about embedding Python.)
372- It calls :c:func: `PyModule_Create `, which returns a module object, and
373- inserts built-in function objects into the newly created module based upon the
374- table (an array of :c:type: `PyMethodDef ` structures) found in the module definition.
375- :c:func: `PyModule_Create ` returns a pointer to the module object
376- that it creates. It may abort with a fatal error for
377- certain errors, or return ``NULL `` if the module could not be initialized
378- satisfactorily. The init function must return the module object to its caller,
379- so that it then gets inserted into ``sys.modules ``.
378+ :c:func: `!PyInit_spam ` is called when each interpreter imports its module
379+ :mod: `!spam ` for the first time. (See below for comments about embedding Python.)
380+ A pointer to the module definition must be returned via :c:func: `PyModuleDef_Init `,
381+ so that the import machinery can create the module and store it in ``sys.modules ``.
380382
381383When embedding Python, the :c:func: `!PyInit_spam ` function is not called
382384automatically unless there's an entry in the :c:data: `PyImport_Inittab ` table.
@@ -433,23 +435,19 @@ optionally followed by an import of the module::
433435
434436.. note ::
435437
436- Removing entries from ``sys.modules `` or importing compiled modules into
437- multiple interpreters within a process (or following a :c:func: `fork ` without an
438- intervening :c:func: `exec `) can create problems for some extension modules.
439- Extension module authors should exercise caution when initializing internal data
440- structures.
438+ If you declare a global variable or a local static one, the module may
439+ experience unintended side-effects on re-initialisation, for example when
440+ removing entries from ``sys.modules `` or importing compiled modules into
441+ multiple interpreters within a process
442+ (or following a :c:func: `fork ` without an intervening :c:func: `exec `).
443+ If module state is not yet fully :ref: `isolated <isolating-extensions-howto >`,
444+ authors should consider marking the module as having no support for subinterpreters
445+ (via :c:macro: `Py_MOD_MULTIPLE_INTERPRETERS_NOT_SUPPORTED `).
441446
442447A more substantial example module is included in the Python source distribution
443- as :file: `Modules/xxmodule .c `. This file may be used as a template or simply
448+ as :file: `Modules/xxlimited .c `. This file may be used as a template or simply
444449read as an example.
445450
446- .. note ::
447-
448- Unlike our ``spam `` example, ``xxmodule `` uses *multi-phase initialization *
449- (new in Python 3.5), where a PyModuleDef structure is returned from
450- ``PyInit_spam ``, and creation of the module is left to the import machinery.
451- For details on multi-phase initialization, see :PEP: `489 `.
452-
453451
454452.. _compilation :
455453
790788 {NULL, NULL, 0, NULL} /* sentinel */
791789 };
792790
793- static struct PyModuleDef keywdargmodule = {
794- PyModuleDef_HEAD_INIT,
795- "keywdarg",
796- NULL,
797- -1,
798- keywdarg_methods
791+ static struct PyModuleDef keywdarg_module = {
792+ .m_base = PyModuleDef_HEAD_INIT,
793+ .m_name = "keywdarg",
794+ .m_size = 0,
795+ .m_methods = keywdarg_methods,
799796 };
800797
801798 PyMODINIT_FUNC
802799 PyInit_keywdarg(void)
803800 {
804- return PyModule_Create(&keywdargmodule );
801+ return PyModuleDef_Init(&keywdarg_module );
805802 }
806803
807804
@@ -1072,8 +1069,9 @@ why his :meth:`!__del__` methods would fail...
10721069
10731070The second case of problems with a borrowed reference is a variant involving
10741071threads. Normally, multiple threads in the Python interpreter can't get in each
1075- other's way, because there is a global lock protecting Python's entire object
1076- space. However, it is possible to temporarily release this lock using the macro
1072+ other's way, because there is a :term: `global lock <global interpreter lock> `
1073+ protecting Python's entire object space.
1074+ However, it is possible to temporarily release this lock using the macro
10771075:c:macro: `Py_BEGIN_ALLOW_THREADS `, and to re-acquire it using
10781076:c:macro: `Py_END_ALLOW_THREADS `. This is common around blocking I/O calls, to
10791077let other threads use the processor while waiting for the I/O to complete.
@@ -1259,32 +1257,26 @@ two more lines must be added::
12591257 #include "spammodule.h"
12601258
12611259The ``#define `` is used to tell the header file that it is being included in the
1262- exporting module, not a client module. Finally, the module's initialization
1263- function must take care of initializing the C API pointer array::
1260+ exporting module, not a client module. Finally, the module's :c:data: ` mod_exec
1261+ <Py_mod_exec> ` function must take care of initializing the C API pointer array::
12641262
1265- PyMODINIT_FUNC
1266- PyInit_spam(void )
1263+ static int
1264+ spam_module_exec(PyObject * m )
12671265 {
1268- PyObject *m;
12691266 static void *PySpam_API[PySpam_API_pointers];
12701267 PyObject *c_api_object;
12711268
1272- m = PyModule_Create(&spammodule);
1273- if (m == NULL)
1274- return NULL;
1275-
12761269 /* Initialize the C API pointer array */
12771270 PySpam_API[PySpam_System_NUM] = (void *)PySpam_System;
12781271
12791272 /* Create a Capsule containing the API pointer array's address */
12801273 c_api_object = PyCapsule_New((void *)PySpam_API, "spam._C_API", NULL);
12811274
12821275 if (PyModule_Add(m, "_C_API", c_api_object) < 0) {
1283- Py_DECREF(m);
1284- return NULL;
1276+ return -1;
12851277 }
12861278
1287- return m ;
1279+ return 0 ;
12881280 }
12891281
12901282Note that ``PySpam_API `` is declared ``static ``; otherwise the pointer
@@ -1343,20 +1335,16 @@ like this::
13431335
13441336All that a client module must do in order to have access to the function
13451337:c:func: `!PySpam_System ` is to call the function (or rather macro)
1346- :c:func: `!import_spam ` in its initialization function::
1338+ :c:func: `!import_spam ` in its :c:data: ` mod_exec <Py_mod_exec> ` function::
13471339
1348- PyMODINIT_FUNC
1349- PyInit_client(void )
1340+ static int
1341+ client_module_exec(PyObject *m )
13501342 {
1351- PyObject *m;
1352-
1353- m = PyModule_Create(&clientmodule);
1354- if (m == NULL)
1355- return NULL;
1356- if (import_spam() < 0)
1357- return NULL;
1343+ if (import_spam() < 0) {
1344+ return -1;
1345+ }
13581346 /* additional initialization can happen here */
1359- return m ;
1347+ return 0 ;
13601348 }
13611349
13621350The main disadvantage of this approach is that the file :file: `spammodule.h ` is
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