Am 10.06.2014 18:28, schrieb Brandon Kohn:
On 6/9/2014 14:13 PM, Olaf Peter wrote:
attached my 'playground', it's basically the UDT example simplified extended with math_round capabilities. The range_checker also checks on finite values, but I'm not sure if this is really required (I would say yes, since operator[<,>} wouldn't work on NaN or Inf). Line 486 doesn't compile - vice versa doesn't work for some reasons.
A couple of points:
1) the range checker you've implemented expects that value is always of type core::intrinsic_type<T> as it calls value.to_builtin(); This fails when the 'Source' type/argument_type is a different type (like int.)
2) On the other hand, when Target is of type core::intrinsic_type<T> and Source is a fundamental type, certain comparison operations fail because the fundamental type doesn't know how to compare with core::intrinsic_type<T>.
In order to get this compiling I had to split the range checker into two specializations like so:
//! Define a custom range checker template<typename Traits, typename OverFlowHandler> struct range_checker;
//! One for checking intrinsic_type against some other type (fundamental) template<typename T, typename SourceT, typename OverFlowHandler> struct range_checker < boost::numeric::conversion_traits<core::intrinsic_type<T>, SourceT> , OverFlowHandler
;
//! And another one for checking other types against intrinsic_type template<typename T, typename TargetT, typename OverFlowHandler> struct range_checker < boost::numeric::conversion_traits<TargetT, core::intrinsic_type<T>> , OverFlowHandler
;
thank you for pointing this out.
I should note that in each of these specializations care must be taken that bounds are properly checked given the context of the conversion direction. In my test I essentially converted the fundamental type to an instance of intrinsic_type (via the template constructor) and then used that to compare with the bounds of the intrinsic_type<T>. In a real world example this is possibly nonsense.
I thought this is what the checker does already, including test on NaN and Inf. Could you explain this? Thank you, Olaf