// In header: <boost/convert/base.hpp>
template<typename > 
struct cnvbase {
  // types
  typedef cnvbase                this_type;  
  typedef int                    int_type;   
  typedef unsigned int           uint_type;  
  typedef long int               lint_type;  
  typedef unsigned long int      ulint_type; 
  typedef short int              sint_type;  
  typedef unsigned short int     usint_type; 
  typedef long long int          llint_type; 
  typedef unsigned long long int ullint_type;
  typedef float                  flt_type;   
  typedef double                 dbl_type;   
  typedef long double            ldbl_type;  
  // construct/copy/destruct
  cnvbase();
  // public member functions
  template<typename type_in, typename type_out> 
    void operator()(type_in const &, boost::optional< type_out > &) const;
   BOOST_CNV_TO_STRING(int_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(uint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(lint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(llint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(ulint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(ullint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(sint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(usint_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(flt_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(dbl_type, optional< string_type > &) const;
   BOOST_CNV_TO_STRING(ldbl_type, optional< string_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< int_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< uint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< lint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< llint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< ulint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< ullint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< sint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< usint_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< flt_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< dbl_type > &) const;
   BOOST_CNV_STRING_TO(string_type const &, optional< ldbl_type > &) const;
   BOOST_CNV_PARAM(base, base::type);
   BOOST_CNV_PARAM(adjust, adjust::type);
   BOOST_CNV_PARAM(precision, int);
   BOOST_CNV_PARAM(precision, int);
   BOOST_CNV_PARAM(uppercase, bool);
   BOOST_CNV_PARAM(skipws, bool);
   BOOST_CNV_PARAM(width, int);
   BOOST_CNV_PARAM(fill, char);
  // protected member functions
  template<typename string_type, typename out_type> 
    void str_to_(string_type const &, optional< out_type > &) const;
  template<typename in_type, typename string_type> 
    void to_str_(in_type, optional< string_type > &) const;
  template<typename char_type> 
    void format_(char_type *, char_type *&, char_type *&) const;
  derived_type const & dncast() const;
  derived_type & dncast();
};