Exposing a C++ class instance to a python embedded interpreter

Question

I am looking for a simple way to expose a C++ class instance to a python embedded interpreter.

• I have a C++ library. This library is wrapped (using swig for th

Answer 1

For reference, here is how you can achieve this using pybind11:

#include 
#include 
namespace py = pybind11;

// Define C++ class "Foo"
class Foo {
    std::string s_;
public:
    Foo(const std::string &s) : s_(s) {}
    void doSomething() { std::cout << s_ << std::endl; }
};
typedef std::shared_ptr FooPtr;

// Define Python module "bar" and Python class "bar.Foo" wrapping the C++ class
PYBIND11_MODULE(bar, m) {
    py::class_(m, "Foo")
        .def("doSomething", &Foo::doSomething);
}

int main(int argc, char **argv)
{
    // Create a C++ instance of Foo
    FooPtr foo = std::make_shared("Hello, World!");

    // Initialize Python interpreter and import bar module
    PyImport_AppendInittab("bar", PyInit_bar);
    Py_Initialize();
    PyRun_SimpleString("import bar");

    // Make C++ instance accessible in Python as a variable named "foo"
    py::module main = py::module::import("__main__");
    main.attr("foo") = foo;

    // Run some Python code using foo
    PyRun_SimpleString("foo.doSomething()");

    // Finalize the Python interpreter
    Py_Finalize();
    return 0;
}