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## Struct template conversion_helper

boost::units::conversion_helper

## Synopsis

    // In header: <boost/units/conversion.hpp>

    template<typename From, typename To>
    struct conversion_helper {

      // public static functions
      static BOOST_CONSTEXPR To convert(const From &);
    };

## Description

Template for defining conversions between quantities. This template should be specialized for every quantity that allows conversions. For example, if you have a two units called pair and dozen you would write

    namespace boost {
    namespace units {
    template<class T0, class T1>
    struct conversion_helper<quantity<dozen, T0>, quantity<pair, T1> >
    {
        static quantity<pair, T1> convert(const quantity<dozen, T0>& source)
        {
            return(quantity<pair, T1>::from_value(6 * source.value()));
        }
    };
    }
    }

In most cases, the predefined specializations for `unit` and `absolute` should be sufficient, so users should rarely need to use this.

### `conversion_helper` public static functions

1.     static BOOST_CONSTEXPR To convert(const From &);