nice! But for some reason I believe this would work for argument functions
double f(quantity<si::length> v){ return 1.;} ... quantity<cgs::lengh> A = 4.*cgs::centimeter f(A); // doesn't work! not matching function
why is this? isn't the argument of the call a sort of construction argument for the function argument, or is more like a plain assignment. Is there a way to force the automatic conversion of the function call.
Or I am forced to use this other long call?
f(quantity<si::length>(A));
Yes. The constructor is explicit.
Or you can write it as a template function that takes any argument that is a quantity of length : #include <iostream> #include <boost/units/io.hpp> #include <boost/units/systems/cgs.hpp> #include <boost/units/systems/si.hpp> using namespace boost::units; template<class System,class Y> Y f(quantity<unit<length_dimension,System>,Y> v) { const Y w = quantity<si::length,Y>(v).value(); std::cout << v << "\t" << w << std::endl; return w; } int main(void) { f(quantity<cgs::length,double>(17.0*cgs::centimeters)); return 0; } Matthias