#include <boost/units/quantity.hpp>

#include <boost/units/systems/si.hpp>

#include <boost/units/base_units/us/foot.hpp>

using namespace boost::units;

 

class Test {

  public:

    // takes any unit of length

    template<class System>

    void setX(quantity<unit<length_dimension,System> > const& x) {

      // explicit conversion to si::length = meters

      m_X = quantity<si::length>(x);

    }

  private:

    quantity<si::length> m_X;

};