AMDG David Walthall <walthall <at> stanfordalumni.org> writes:
Here is my review of the proposed Boost.Units library.
<snip>
* What is your evaluation of the design?
The only complaint I have is that unique values of ordinal<N> have to be used.
<snip>
Nod. The only way to prevent collisions is to use more bits and either guids or compile time strings storing the fully qualified name.
<snip>
It would be nice if the typedef for a new type, such as molar_energy_type, was something like: composite_dimension<energy_type,1, amount_type,-1>::type instead of: composite_dimension<length_tag,2, mass_tag,1, time_tag,-2, amount_tag,-1>::type
The existing composite_dimension<> is more efficient. If we made such a template it should work for quantities and units, too. composite<SI::energy, 1, SI::amount, -1>::type template<class T0 = dimensionless_type, int E0 = 0, class T1 = dimensionless_type, int E1 = 0, class T2 = dimensionless_type, int E2 = 0, ...
struct composite { typedef typename static_power<T0, static_rational<E0> >::type t0; typedef typename static_power<T1, static_rational<E1> >::type t1; typedef typename static_power<T2, static_rational<E2> >::type t2; ... typedef t0 type0; typedef typename static_multiply<type0, t1>::type type1; typedef typename static_multiply<type1, t2>::type type2; ... typedef typeN type; };
<snip>
My final suggestion is that CODATA constants should be available for libraries that do not support typeof. (I expect that this will be fairly straightforward since the units are known.)
Boost.Typeof is in 1.34 and we have support for emulation.
<snip>
Thank you for your review. In Christ, Steven Watanabe