// In header: <boost/log/utility/setup/formatter_parser.hpp>
template<typename CharT, typename AttributeValueT> 
class basic_formatter_factory : public boost::log::formatter_factory< CharT > {
public:
  // types
  typedef AttributeValueT           value_type;      // Attribute value type. 
  typedef base_type::formatter_type formatter_type;
  typedef base_type::args_map       args_map;      
  // public member functions
  virtual formatter_type 
  create_formatter(attribute_name const &, args_map const &);
};