// Copyright David Abrahams 2002. // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #ifndef AS_TO_PYTHON_FUNCTION_DWA2002121_HPP # define AS_TO_PYTHON_FUNCTION_DWA2002121_HPP # include namespace boost { namespace python { namespace converter { // Given a typesafe to_python conversion function, produces a // to_python_function_t which can be registered in the usual way. template struct as_to_python_function { // Assertion functions used to prevent wrapping of converters // which take non-const reference parameters. The T* argument in // the first overload ensures it isn't used in case T is a // reference. template static void convert_function_must_take_value_or_const_reference(U(*)(T), int, T* = 0) {} template static void convert_function_must_take_value_or_const_reference(U(*)(T const&), long ...) {} static PyObject* convert(void const* x) { convert_function_must_take_value_or_const_reference(&ToPython::convert, 1L); // Yes, the const_cast below opens a hole in const-correctness, // but it's needed to convert auto_ptr to python. // // How big a hole is it? It allows ToPython::convert() to be // a function which modifies its argument. The upshot is that // client converters applied to const objects may invoke // undefined behavior. The damage, however, is limited by the // use of the assertion function. Thus, the only way this can // modify its argument is if T is an auto_ptr-like type. There // is still a const-correctness hole w.r.t. auto_ptr const, // but c'est la vie. return ToPython::convert(*const_cast(static_cast(x))); } #ifndef BOOST_PYTHON_NO_PY_SIGNATURES static PyTypeObject const * get_pytype() { return ToPython::get_pytype(); } #endif }; }}} // namespace boost::python::converter #endif // AS_TO_PYTHON_FUNCTION_DWA2002121_HPP