C++ module definition

#include <boost/python/enum.hpp>
#include <boost/python/def.hpp>
#include <boost/python/module.hpp>

using namespace boost::python;

enum color { red = 1, green = 2, blue = 4 };

color identity_(color x) { return x; }

BOOST_PYTHON_MODULE(enums)
{
    enum_<color>("color")
        .value("red", red)
        .value("green", green)
        .export_values()
        .value("blue", blue)
        ;

    def("identity", identity_);
}

Interactive Python:

>>> from enums import *

>>> identity(red)
enums.color.red

>>> identity(color.red)
enums.color.red

>>> identity(green)
enums.color.green

>>> identity(color.green)
enums.color.green

>>> identity(blue)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'blue' is not defined

>>> identity(color.blue)
enums.color.blue

>>> identity(color(1))
enums.color.red

>>> identity(color(2))
enums.color.green

>>> identity(color(3))
enums.color(3)

>>> identity(color(4))
enums.color.blue

>>> identity(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: bad argument type for built-in operation