Re: [boost] Re: Units libraries... (long reply)

From: Matthias Schabel (boost_at_[hidden])
Date: 2004-01-12 22:17:50

> I just want to note that support of std::complex would require
> operators with mixed underlying types. That is,
>
>   template <typename u1, typename u2, typename v1, typename v2>
>   unit<unit_product_type<u1, u2>::type, number_product_type<v1,  
> v2>::type>
>   operator* (unit<u1, v1>, unit <u2, v2>) { ... }
>
> rather than
>
>   template <typename u1, typename u2, typename v>
>   unit<unit_product_type<u1, u2>::type, v>
>   operator* (unit<u1, v>, unit <u2, v>) { ... }
>
> This is because one would frequently need to multiply a complex by a  
> real.

This is a good point - in fact, since I'm allowing user-defined classes  
as value types,
I really should template multiplication and division on two classes.   
Unfortunately,
that means that there needs to be a definition of  
multiply<T,V>::type...  Hmm...
>
> Maybe std::complex< unit<electric_current, double> > is not such a bad  
> idea?

Could also work, I suppose.  Seems backwards to me, though.

------------------------------------------------------------------------ 
---------------------------
Matthias Schabel, Ph.D.                           	
Utah Center for Advanced Imaging Research
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