Call Python functions from C++ on Ubuntu 12.04

Linux Programming

Code

/home/shinya/py_example/mymain.py

import sys

def main(args):
    sys.stdout.write('Hello, world!\n');
    if args:
        sys.stdout.write('{0}\n'.format(args))

/home/shinya/py_example/main.cc

#include <Python.h>

#include <cassert>
#include <iostream>

int main(int argc, char** argv) {
  Py_Initialize();
  assert(Py_IsInitialized());

  const char* kModuleName = "mymain";
  PyObject* module_name = PyString_FromString(kModuleName);
  PyObject* module = PyImport_Import(module_name);

  PyObject* dic = PyModule_GetDict(module);
  const char* kFuncName = "main";
  PyObject* main_func = PyDict_GetItemString(dic, kFuncName);
  assert(PyCallable_Check(main_func));

  PyObject* main_args = PyTuple_New(1);
  PyObject* main_args_0 = PyString_FromString("Hello, Python!");
  PyTuple_SetItem(main_args, 0, main_args_0);
  PyObject_CallObject(main_func, main_args);

  // raise Exception
  PyObject_CallObject(main_func, NULL);
  PyErr_Print();

  Py_Finalize();
  return 0;
}

Check

$ export PYTHONPATH=${PYTHONPATH}:/home/shinya/py_example
$ g++ -Wall -I/usr/include/python2.7 main.cc -lpython2.7
$ ./a.out
Hello, world!
Hello, Python!
TypeError: main() takes exactly 1 argument (0 given)

References