embedding python

PeterG picture PeterG · Nov 22, 2011 · Viewed 7.2k times · Source

Im trying to call python functions from C code, and i followed a sample from here

I also have the correct include file directries, library directries, and linked the python32.lib (im using python 32) however the error was that python/C APIs such as PyString_FromString, PyInt_FromLong, PyInt_AsLong are undefined (error in the debugger)

this is strange because im also using other APIs, but they're all fine...

whats the problem here??

int
main(int argc, char *argv[])
{
    PyObject *pName, *pModule, *pDict, *pFunc;
    PyObject *pArgs, *pValue;
    int i;

    if (argc < 3) {
        fprintf(stderr,"Usage: call pythonfile funcname [args]\n");
        return 1;
    }

    Py_Initialize();
    pName = PyString_FromString(argv[1]);
    /* Error checking of pName left out */

    pModule = PyImport_Import(pName);
    Py_DECREF(pName);

    if (pModule != NULL) {
        pDict = PyModule_GetDict(pModule);
        /* pDict is a borrowed reference */

Py_Initialize(), PyImport_Import(), PyModule_GetDict() all work fine, but not PyString_FromString...

Answer

yak picture yak · Nov 22, 2011

The example code you used is for ancient Python version, 2.3.2. Python 3.x line introduced a number of incompatibilites not only in the language but in the C API as well.

The functions you mention simply no longer exist in Python 3.2.

PyString_ functions were renamed to PyBytes_.

PyInt_ functions are gone, PyLong_ should be used instead.

Here's the same example that you've used but for Python 3:

5.3. Pure Embedding

Note that it's using PyUnicode_ instead of PyString_/PyBytes_. In many places where Python 2.x used byte strings, Python 3.x uses unicode strings.

By the way, I usually use this page to look up all possible calls:

Index – P