Question

I would like to gather multiple Python modules under one package, so they do not reserve too many names from global set of python packages and modules. But I have problems with modules that are written in C.

Here is a very simple example, straight from the official Python documentation. You can find it at the bottom of the page from here: http://docs.python.org/distutils/examples.html

from distutils.core import setup
from distutils.extension import Extension
setup(name='foobar',
      version='1.0',
      ext_modules=[Extension('foopkg.foo', ['foo.c'])],
      )

My foo.c file looks like this

#include <Python.h>

static PyObject *
foo_bar(PyObject *self, PyObject *args);

static PyMethodDef FooMethods[] = {
    {
        "bar",
        foo_bar,
        METH_VARARGS,
        ""
    },
    {NULL, NULL, 0, NULL}
};

static PyObject *
foo_bar(PyObject *self, PyObject *args)
{
    return Py_BuildValue("s", "foobar");
}

PyMODINIT_FUNC
initfoo(void)
{
    (void)Py_InitModule("foo", FooMethods);
}

int
main(int argc, char *argv[])
{
    // Pass argv[0] to the Python interpreter
    Py_SetProgramName(argv[0]);

    // Initialize the Python interpreter.  Required.
    Py_Initialize();

    // Add a static module
    initfoo();

    return 0;
}

It builds and installs fine, but I cannot import foopkg.foo! If I rename it to just “foo” it works perfectly.

Any ideas how I can make the “foopkg.foo” work? For example changing “foo” from Py_InitModule() in C code to “foopkg.foo” does not help.

Answer 1

There must be an __init__.py file in the foopkg folder, otherwise Python does not recognize as a package.

Create a foopkg folder where setup.py is, and put an empty file __init__.py there, and add a packages line to setup.py:

from distutils.core import setup
from distutils.extension import Extension
setup(name='foobar',
      version='1.0',
      packages=['foopkg'],
      ext_modules=[Extension('foopkg.foo', ['foo.c'])],
      )