// In header: <boost/log/expressions/formatters/format.hpp>
template<typename CharT> 
class format_terminal {
public:
  // types
  typedef CharT                          char_type;    // Character type. 
  typedef unspecified                    format_type;  // Boost.Format formatter type. 
  typedef std::basic_string< char_type > string_type;  // String type. 
  typedef format_type::pump              result_type;  // Terminal result type. 
  // construct/copy/destruct
  explicit format_terminal(const char_type *);
  format_terminal() = delete;
  // public member functions
  template<typename ContextT> result_type operator()(ContextT const &) const;
};