[C++-sig] wrapping boost::optional

[Neal D. Becker]

I'm trying to wrap boost::optional<T>.  I have an adequate solution here:

#include <boost/optional.hpp>
#include <boost/python/module.hpp>
#include <boost/python/def.hpp>
#include <boost/python/class.hpp>
#include <boost/python/init.hpp>
#include <boost/python/operators.hpp>

using namespace boost::python;

template<typename T>
inline void set (boost::optional<T>& o, T x) {
  o = x;
}
  
template<typename T>
inline T get (boost::optional<T>& o) {
  return o.get();
}

#define OPTIONAL(T)\
  class_<boost::optional<T> >("opt_"#T) \
    .def ("set", &set<T>) \
    .def ("get", &get<T>) \
    .def (!(self)) \
    ;

BOOST_PYTHON_MODULE(optional_wrap)
{
  OPTIONAL(int)
  
  OPTIONAL(double)
}

What would be better, though, is that if the option is not initialized, it
should return None in response to get.  That would be more pythonic, no? 
Problem is, I don't know how to do that.  Any hints?