[C++-sig] Boost::Python and Functions with String Inputs

[Hesam]

*Dear Sirs,*

*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. Actually this comes from Boost::Python
tutorials
http://www.boost.org/doc/libs/1_51_0/libs/python/doc/tutorial/doc/html/python/exposing.html

*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
( obj.greet() ) but when I want to access functions with string input
(obj.set("Hello") ) I get memory access violation ("Access violation
reading location 0xffffffffffffffff"). *The problem is just with string
inputs. i.e. if I change function set(string) to set(char*) it works fine. *

If instead of interpreter I use PyRun_SimpleString("import hello;
w=hello.World(); w.set('Hi there');\n"); I get error "Expression
_BLOCK_TYPE_IS_VALID(pHead->nBlockUse)". The point is when I make
breakpoint inside the function value of string is not what I want.

*Details*: Visual studio 2010 (MDd mode), Debug Mode, x64, Win7

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

[image: Inline image 1]
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