[boost] Re: boost::numeric::converter

From: Fernando Cacciola (fernando_cacciola_at_[hidden])
Date: 2004-01-26 14:33:06

"Andy Little" <andy_at_[hidden]> escribió en el mensaje
news:bv1kl9$me6$1_at_sea.gmane.org...
> Thanks Fernando Cacciola...The converter is great ... I love it... :-)
>

:-) You're welcomne.

> #include <iostream>
> #include <limits>
> #include "boost/numeric/converter.hpp"
>
> template<typename T, typename S>
> struct converter : boost::numeric::converter<
>     T,
>     S,
>     typename boost::numeric::conversion_traits<T,S>,
>     typename boost::numeric::def_overflow_handler,
>     boost::numeric::Round<
>         typename boost::numeric::conversion_traits<
>             T,
>             S
>         >::source_type
>     >,
>     boost::numeric::raw_converter<
>         typename boost::numeric::conversion_traits<
>             T,
>             S
>         >
>     >,
>     boost::numeric::UseInternalRangeChecker
> >{};
>
> //Of course could specialise converter<X,Y>
>
> // value_type_traits
> // Value_type with user definable conversion
> template<
>     typename Value_type,
>     template<
>         typename T,
>         typename S
>     > class Converter
> >
> struct value_type_traits
> {
>     typedef Value_type value_type;
>     template <typename V>
>     static Value_type convert_to_value_type( V v)
>     {
>         return Converter<Value_type,V>::convert(v);
>     }
>     template <typename V>
>     static V convert_from_value_type( V v)
>     {
>         return Converter<V,Value_type>::convert(v);
>     }
> };
>
> int main()
> {
>     try{
>         typedef value_type_traits<int,converter> v_traits;
>         //whatever
>         std::cout << v_traits::convert_to_value_type(100000000.5) <<'\n';
>         std::cout << v_traits::convert_from_value_type(65535) << '\n';
>     }
>     catch (std::exception e){
>         std::cout << "failed with " << e.what() << '\n';;
>     }
> }
> /*output:
> 100000001
> 65535
> */
>
I see.
The idea is that the user of value_type_traits plugs in her own converter,
which can be easily composed out of boost::numeric::converter by derivation.
Looks nice to me.

Cheers,

Fernando Cacciola
SciSoft