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

28 May 2008


      AMDG

Torsten Mähne wrote:
...
I noticed that currently Units and Lambda use two independent systems of
trait classes to determine the return type of algebraic operations like
+, -, *, /.
Boost.Units actually relies on Boost.Typeof for user types.
...
- Can some of the partial specializations be dropped?
I don't think so.
...
- Is there a need to add other specializations
  (e.g, for boost::units::unit<Dim, System, Enable>)?
Drop the Enable parameter, it's an implementation detail which I plan to 
remove soon.
...
- 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)); }
};

In Christ,
Steven Watanabe