Re: [Boost-users] [units] Creating specific unit quantities

On Mon, Mar 7, 2011 at 5:35 PM, Matthias Schabel wrote:

// takes any unit of length template<class System> void setX(quantity > const& x) { // explicit conversion to si::length = meters m_X = quantitysi::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 to quantity is allowed if Yand Z are implicitly convertible. quantity to quantity explicit conversion between quantity and quantity is allowed if Unit1 and Unit2 have the same dimensions and if Y and Z are implicitly convertible. quantity to quantity Both have the same length dimension. implicit conversion between quantity and quantity 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