[C++-sig] def_visitor

[David Abrahams]

I have just checked in changes which cause all class_<...>::def
invocations which aren't applied to [member] function pointers to go
through a new def_visitor<...> interface.  Examples are:

        .def(init<...>())

        .def("foo", some_callable_python_object)

        .def(self + int)

        .def(vector_indexing_suite<...>(...))

This gives us a simple non-intrusive way to add new def()
functionality and lays the groundwork for pure_virtual() and the new
init function generator.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com