Re: [boost] [Units] A first step to ease the usage of Units' quantities inside of functors created with the Lambda library

From: Torsten Maehne (Torsten.Maehne_at_[hidden])
Date: 2008-06-06 10:01:21

Hello Steven,

Steven Watanabe wrote:
>> - Is there a way to work around boost::lambda:bind's limitation
>>   concerning the binding of overloaded functions? The required
>>   static_cast to the function pointer (referring, e.g., a function
>>   from boost/units/cmath.hpp) is tedious.
>>   
> 
> The problem is avoided by creating a function object.  (untested)
> 
> struct sin_t {
>     template<class Args>
>     struct sig {
>         typedef typename boost::tuples::element<0>::type arg1_type;
>         BOOST_TYPEOF_NESTED_TYPEDEF(nested, (sin(make<arg1_type>())));
>         typedef typename nested::type type;
>     };
>     template<class T>
>     ... operator()(const T& arg) { return(sin(arg)); }
> };

I finally came around to test your proposed solutions: I got it working
in the attached small example for two cases sin() and
pow<static_rational<N, D> >(). What do you think about a header
cmath_functor.hpp, which would collect functors under, e.g.,
boost::units::functor to replace the cmath functions in lambda expressions?

Best regards,

Torsten