// In header: <boost/log/utility/manipulators/to_log.hpp>
template<typename T, typename TagT = void> 
class to_log_manip {
public:
  // types
  typedef T    value_type;  // Output value type. 
  typedef TagT tag_type;    // Value tag type. 
  // construct/copy/destruct
  explicit to_log_manip(value_type const &) noexcept;
  to_log_manip(to_log_manip const &) noexcept;
  // public member functions
  value_type const & get() const noexcept;
};