如何在python 3.x中初始化模块以便可以导入？

Question

In Python 2.7 I'd do

void InitPython()
{
    ..
    Py_InitModule3("my_prog", ProgMethods, "documentation");
    ..
}

Then I will simply be able to do import my_prog like this in my c++ code

char strCode[] = "import my_prog, sys, os\n"

PyRun_SimpleString (strCode);

---

However in Python 3.6 , following the official documentation and applying the changes doesn't work

static struct PyModuleDef moduledef = {
    PyModuleDef_HEAD_INIT,
    "my_prog",                          /* m_name */
    "documentation",                    /* m_doc */
    -1,                                 /* m_size */
    ProgMethods,                        /* m_methods */
    NULL,                               /* m_reload */
    NULL,                               /* m_traverse */
    NULL,                               /* m_clear */
    NULL,                               /* m_free */
};

void InitPython()
{
    ..
    PyObject *m1 = PyModule_Create(&moduledef);
    ..
}

Fails with following error:

ModuleNotFoundError: No module named 'my_prog'

How to fix this?

Answer 1

The documentation I can find says your initialization function should be named PyInit_mymodule and marked with PyMODINIT_FUNC :

static PyMethodDef SpamMethods[] = {
    // ...
    {"system",  spam_system, METH_VARARGS, "Execute a shell command."},
    // ...
    {NULL, NULL, 0, NULL}        /* Sentinel */
};

// ...

static struct PyModuleDef spammodule = {
    PyModuleDef_HEAD_INIT,
    "spam",
    spam_doc,
    -1,
    SpamMethods
};

// ...

PyMODINIT_FUNC
PyInit_spam(void)
{
    return PyModule_Create(&spammodule);
}

(As an aside, unless you really do need to create your extension in C, I'd recommend looking at Cython too.)