Exporting wrapped functions doesn't work

[m-u-xyz]

I find myself in need of exporting a whole lot of functions to Python which require a wrapper (the API needs locking and whatnot).

The following code probably should work (pybind11 can handle it, for the most part), but doesn't.

#include <iostream>
#include <boost/python.hpp>

template <class R, class... Args>
struct wrap
{
    using funct_type = R(*)(Args...);
    funct_type func;
    wrap(funct_type f): func(f) {};
    R operator()(Args&&... args)
    {
          std::cout << "before calling\n";
          R ret=func(std::forward<Args>(args)...);
          std::cout << "After calling\n";
          return ret;
    }
};

class bar {};
class foo : bar {
    public:
    enum xfoo { FOO=1, BAR=2, BAZ=3    };
    static int add(int a, int b, enum xfoo c) { return a+b; }
    static int add2(int a, int b) { return a+b; }
};

BOOST_PYTHON_MODULE(example)
{
    using namespace boost::python;

    // this works
    std::cout << "Result" << wrap{foo::add}(1,2, foo::xfoo::FOO) << std::endl;

    // so does this
    def("add", foo::add, "A function that adds two numbers and no enum");

    // this works with pybind11 but not boost
    def("add2", wrap{foo::add2}, "A function that adds two numbers");

    // this works with neither
    def("add", wrap{foo::add}, "A function that adds two numbers and no enum");
}