I'm trying to build an extension module and was having problems so I decided
to try something simpler. Article 16.5, "Coding the Methods of a Python
Class in C" in the first edition of the Python Cookbook looked about right.
I generated the code and a setup.py file (shown below). When I run
python setup.py build_ext --inplace
I get the following errors:
LINK : error LNK2001: unresolved external symbol init_Foo
build\temp.win32-2.7\Release\_Foo.lib : fatal error LNK1120: 1 unresolved
externals
If I change the name of the initialization function from Foo_init (as in the
book) to init_Foo the build succeeds but import _Foo fails:
import _Foo
SystemError: dynamic module not initialized properly
This is the problem I was having with the extension module I was trying to
write.
What can I do to correct this?
I'm using Python 2.7 on Win XP.
==========================================================
# File: setup.py
from setuptools import setup, Extension
setup(name='Foo',
version='0.1',
ext_modules=[Extension('_Foo', ['Foo.c'],
include_dirs=['C:\Program Files\Common Files\Microsoft\Visual C++ for
Python\9.0\VC\include',
'C:\Miniconda\include'],
)],
)
=================================================
# File: Foo.c
#include <Python.h>
PyObject* init_Foo(PyObject *self, PyObject *args){
printf("Foo.__init__ called\n");
Py_INCREF(Py_None);
return Py_None;
}
static PyObject* Foo_doSomething(PyObject *self, PyObject *args){
printf("Foo.doSomething called\n");
Py_INCREF(Py_None);
return Py_None;
}
static PyMethodDef FooMethods[] = {
{"__init__", init_Foo, METH_VARARGS, "doc_string"},
{"doSomething", Foo_doSomething, METH_VARARGS, "doc string"},
{0, 0},
};
static PyMethodDef ModuleMethods[] = {{0,0}};
void initFoo() {
PyMethodDef *def;
PyObject *module = Py_InitModule("Foo", ModuleMethods);
PyObject *moduleDict = PyModule_GetDict(module);
PyObject *classDict = PyDict_New();
PyObject *className = PyString_FromString("Foo");
PyObject *fooClass = PyClass_New(NULL, classDict, className);
PyDict_SetItemString(moduleDict, "Foo", fooClass);
Py_DECREF(classDict);
Py_DECREF(className);
Py_DECREF(fooClass);
for (def = FooMethods; def->ml_name != NULL; def++) {
PyObject *func = PyCFunction_New(def, NULL);
PyObject *method = PyMethod_New(func, NULL, fooClass);
PyDict_SetItemString(classDict, def->ml_name, method);
Py_DECREF(func);
Py_DECREF(method);
}
}
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