// In header: <boost/program_options/errors.hpp>

class invalid_syntax : public boost::program_options::error_with_option_name {
public:
  enum kind_t { long_not_allowed = = 30, long_adjacent_not_allowed, 
                short_adjacent_not_allowed, empty_adjacent_parameter, 
                missing_parameter, extra_parameter, unrecognized_line };
  // construct/copy/destruct
  invalid_syntax(kind_t, const std::string & = "", const std::string & = "", 
                 int = 0);
  ~invalid_syntax();
  // public member functions
  kind_t kind() const;
  virtual std::string tokens() const;
  // protected member functions
  std::string get_template(kind_t);
};