[Boost-users] [Units][Interval] Using both together

Subject: [Boost-users] [Units][Interval] Using both together
From: Anubis (kerub_at_[hidden])
Date: 2009-07-03 13:30:44

Hello all!

First let me congratule Matthias and Steven for the great units library. 
Just recently I have kicked out my own attempt at something like it and 
switched to boost::units.

However I ran into trouble using both boost::units and boost::interval 
because a single int cannot be static casted to a quantity.

So one could either provide a function like:
static boost::units::quantity<Unit,Y> quantity(int aValue) { 
boost::units::quantity<Unit,Y>::from_value(aValue); }

Probably not the best idea as any value would get casted to a quantity 
without notice, therefore totally ruining the concept of from_value.

Or as I have implemented a specific checking policy for boost::interval:

#include <boost/numeric/interval.hpp>
//! The checking policy for boost::interval, if it uses boost::unit
/*!
  Look into boost/numeric/interval/checking.hpp to see other possible base
  checking policies for template parameter Checking
*/
namespace boost { namespace units { namespace interval_support {
template<class T, class Checking = 
boost::numeric::interval_lib::checking_base<T> >
struct checking_base : Checking
  {
    static T empty_lower()
    {
      return (std::numeric_limits<T>::has_quiet_NaN ?
      std::numeric_limits<T>::quiet_NaN() : T::from_value(1));
    }
    static T empty_upper()
    {
      return (std::numeric_limits<T>::has_quiet_NaN ?
      std::numeric_limits<T>::quiet_NaN() : T::from_value(0));
    }
};
}}}

And actually use it like this:

#include <boost/units/interval_support.hpp> // or whichever name
typedef
  boost::numeric::interval_lib::change_checking<
    boost::numeric::interval<MY_QUANTITY_TYPE>,
    boost::units::interval_support::checking_base<MY_QUANTITY_TYPE>
  >::type
  my_unit_interval_type;

HTH to easily use boost::units and boost::interval in the future,
Thomas Taylor