• boost.python
• module

Boost.Python v2 now supports a free-function version of def which defines its function in the current scope:

  #include <boost/python/def.hpp>
  #include <boost/python/module_init.hpp>

  BOOST_PYTHON_MODULE_INIT(my_module)
  {
    def("name", function_ptr);
    def("name", function_ptr, call_policies);
    def("name", function_ptr, "documentation string");
    def("name", function_ptr, call_policies, "documentation string");

    def("name", function_ptr, default_stubs);
  }

etc.

To get access to the current module, you can declare the current scope:

  #include <boost/python/scope.hpp>

  BOOST_PYTHON_MODULE_INIT(my_module)
  {
    // set the docstring of the current module scope
    scope().attr("__doc__") = "my module's docstring";
    ...

    scope current;
    current.attr("x") = 1; // my_module.x = 1
  }

Of course, you can also set the current scope to any object:

  object some_obj;
  scope within(some_obj);
  def("foo", &foo); // define a function within some_obj as a namespace

Be warned, however, that although you can set the current scope from a class_<> instance, the class_<>'s def() member function will work properly in some cases where the free-function def() cannot, since the latter is missing information about the class type being wrapped.