python - How to expose a function which returns a variant vector? -

i'm looking tiny working example of c++ module has method returns variant vector , exposes python (it seems ancient problem, dates 2004, not find clear answers onwards). i've read this , this , more, still can not find solution. documentation seems throw reader tons of information right away. want tiny working example 1 tiny method returns 1 tiny vector. have now:

#include <boost/variant.hpp> #include <boost/python.hpp> #include <vector>  using namespace std; using namespace boost:python  typedef boost::variant<int> variant; typedef vector<variant> vector;  class some{    private:       int idx;    public:       some(...){ ... } //not important       vector mymethod(){           return vector{1};       }  };  boost_python_module(some){     class_<vector>("vector").def(vector_indexing_suite<vector, true>());     class_<some>("some",         init ... //not important         .def("mymethod",&some::mymethod); } 

i have no problems compilation, linkage , usage of resulting shared library, if comment out method. however, if there such method returning vector, whole stack of errors. guess, need make steps, playing drums , doing other magic stuff (or data types conversion etc), not know steps.

you should write to_python_converter variant, should work:

#include <boost/python.hpp> #include <boost/python/suite/indexing/vector_indexing_suite.hpp> #include <python.h> #include <vector> #include <boost/variant.hpp>  typedef boost::variant<int> number; typedef std::vector<number> vector;  vector function() {    return vector{1}; }  struct number_to_object : boost::static_visitor<pyobject*> {    static result_type convert(number const& v)    {       return apply_visitor(number_to_object(), v);    }     template<typename t>    result_type operator () (t const& v) const    {       return boost::python::incref(boost::python::object(v).ptr());    } };  void init_module() {}  boost_python_module(pyexc_test) {    using namespace boost::python;     class_<vector>("vector").def(vector_indexing_suite<vector, true>());     to_python_converter<number, number_to_object>();    implicitly_convertible<int, number>();     def("function", function);    def("init_module", init_module); }