Matthias Schabel wrote:
While quantity_reinterpret_cast may not be perfectly analogous to reinterpret_cast, it represents the reinterpretation of a raw number as being of a different type, and so I think it's a pretty good name. Just as importantly, I can't think of anything better. Do you have any other ideas? quantity_unsafe_cast? quantity_arbitrary_cast? :)
Sorry, I think I muddied the waters here - I agree that quantity_reinterpret_cast should be reserved for those cases where access to the raw data is necessary. I was just saying that we can write things like
quantity<SI::length,double> q; quantity<SI::length,int> r; quantity<CGS::length,double> s; quantity<CGS::length,int> t;
q = quantity<SI::length,double>(r); q = quantity<SI::length,double>(s); q = quantity<SI::length,double>(t);
already, so the only non-degenerate use case of quantity_cast is to take a raw value and return a quantity:
q = quantity_cast< quantity<SI::length,double> >(1.5);
I think you are right that quantity_cast becomes unnecessary, and in the last usage there, the user should have to specify the units or use quantity_reinterpret_cast. One more thought, instead of: q = quantity<SI::length,double>(r); what about a syntax like q.convert_from(r) to emphasize that this is performing a safe unit conversion, and to avoid having to repeat the type name? -lewis