...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::functional::distance::result<This(InputIterator, InputIterator)>
// In header: <boost/proto/functional/std/iterator.hpp> template<typename This, typename InputIterator> struct result<This(InputIterator, InputIterator)> { // types typedef typename std::iterator_traits< typename boost::remove_const< typename boost::remove_reference<InputIterator>::type >::type >::difference_type type; };