[C++-sig] libboost-python: how to create module in C++-runtime and use it from python code, in python 3.x

[Nikolay Shaplov]

В письме от пятница, 22 июля 2022 г. 10:39:09 MSK пользователь Nikolay Shaplov 
написал:

I finally managed to fix it. 
Key point here was, that in python3.x you should manually add such modules to 
inittab(whatever it is) using PyImport_AppendInittab

Finally my sample that builds with both 2.7 anx 3.x pythons looks like this

#include <boost/python.hpp>

std::string provide_hello() {
    return "hello world provided";
}

BOOST_PYTHON_MODULE(_hello_provider) {
    using namespace boost::python;
    def("provide_hello", &provide_hello);
}

int main()
{
#if PY_MAJOR_VERSION >= 3
  PyImport_AppendInittab((char*)"_hello_provider", PyInit__hello_provider);
#else
  PyImport_AppendInittab((char*)"_hello_provider", init_hello_provider);
#endif
  Py_InitializeEx(0);

  try {
    boost::python::object modImp = boost::python::import("imp");
    PyImport_AddModule("test_module");

    modImp.attr("load_source")("test_module", "test_module.py");

    boost::python::exec("print(test_var)", 
boost::python::import("test_module").attr("__dict__"));
    boost::python::exec("print(hello_static())", 
boost::python::import("test_module").attr("__dict__"));
    boost::python::exec("print(hello_provided())", 
boost::python::import("test_module").attr("__dict__"));
  }
  catch (const boost::python::error_already_set&)
  {
    PyErr_Print();
  }
  Py_Finalize();
}

Special thanks to https://github.com/TNG/boost-python-examples/tree/main/10-Embedding authors and O02eg from linux.org.ru
-- 
Nikolay Shaplov aka Nataraj
Fuzzing Engineer at Postgres Professional
Matrix IM: @dhyan:nataraj.su
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