On Mon, Mar 7, 2011 at 5:35 PM, Matthias Schabel <boost@schabel-family.org>wrote:
// takes any unit of length template<class System> void setX(quantity<unit<length_dimension,System> > const& x) { // explicit conversion to si::length = meters m_X = quantity<si::length>(x); }
Is the following set of statements correct. si::length has a length_dimension and is part of the si::system. boost::units::si:: meter_base_unit::unit_type has a length_dimension and is part of the si::system. boost::units::us::foot_base_unit::unit_type has a length_dimension and is part of the us system. Since an explicit conversion is needed I definitely don't understand the differences between the following three statements. I've included examples to show my limited understanding. implicit conversion of quantity<Unit,Y> to quantity<Unit,Z> is allowed if Yand Z are implicitly convertible. quantity<si::length, int> to quantity<si::length, double> explicit conversion between quantity<Unit1,Y> and quantity<Unit2,Z> is allowed if Unit1 and Unit2 have the same dimensions and if Y and Z are implicitly convertible. quantity<us::foot_base_unit::unit_type, int> to quantity<si::length, double> Both have the same length dimension. implicit conversion between quantity<Unit1,Y> and quantity<Unit2,Z> is allowed if Unit1 reduces to exactly the same combination of base units as Unit2 and if Y and Z are convertible. I'm not sure on the example for this one. Ryan