Question

Goal: I’m trying to use python interactively in my c++ code using Boost::Python library.
My goal is to change variables of some class which I have defined in c++ from the python interpreter.

The code is attached below.

Problem: I can load the library in python interface (i.e. load hello) and make an object out of it (obj = hello.World()). I even can access functions without variables ( obj.greet() ) but when I want to access functions with variables (obj.Set(“Hello”) ) I get memory access violation (“Access violation reading location 0xffffffffffffffff”). Even when that function is an empty function which just takes some string.

struct World
{
    void set(string _msg) {}
    string greet() { return msg; }
    string msg;
};
typedef boost::shared_ptr<World> World_ptr;
BOOST_PYTHON_MODULE(hello)
{
    bp::class_<World, World_ptr>("World")
        .def("greet", &World::greet)
        .def("set", &World::set)
    ;
}
int main(int argc, char **argv)
{
    Py_Initialize();    

    bp::object main = bp::object(bp::handle<>(bp::borrowed(PyImport_AddModule("__main__"))));
    bp::object global(main.attr("__dict__"));
    inithello();
    // Bring up Python interpreter
    Py_Main(argc, argv);

    Py_Finalize();

    return 0;
}

Actually this comes from Boost::Python tutorials with some modification to use Python interpreter
http://www.boost.org/doc/libs/1_51_0/libs/python/doc/tutorial/doc/html/python/exposing.html

Many thanks

——————— Edit ———————

I tested a lot and found out that the problem is only with string inputs. i.e. No problem with char* or int. Is there any problem with strings in boost python?

Answer 1

I found that I had made a mistake and added static library of boost_python (.lib file) into the linker page. I’m not sure what It was leading to but after I deleted it I found that instead of “boost_python-vc100-mt-1_51.dll” the program is using “boost_python-vc100-mt-gd-1_51.dll”.

Problem is solved, but can anyone explain what was the problem?

Many thanks for all the helps