Explicit cast of a quantity's representation

Synopsis

Declared in <mp‐units/framework/value_cast.h>

template<
    Quantity ToQ,
    typename FwdQ,
    Quantity Q = std::remove_cvref_t<FwdQ>>
requires (ToQ::quantity_spec == Q::quantity_spec) &&
          (MP_UNITS_WEAK_UNIT_OF(MP_UNITS_NONCONST_TYPE(ToQ::unit), Q::quantity_spec)) &&
          std::constructible_from<typename ToQ::rep, typename Q::rep> &&
          detail::SaneScaling<Q::unit, ToQ::unit, typename ToQ::rep>
[[nodiscard]]
constexpr
Quantity auto
value_cast(FwdQ&& q);

Description

Implicit conversions between quantities of different types are allowed only for "safe" (e.g. non‐truncating) conversion. In truncating cases an explicit cast have to be used.

using ToQ = quantity<us, int>; auto q = value_cast<ToQ>(1.23 ms);

Note that value_cast only changes the "representation aspects" (unit and representation type), but not the "meaning" (quantity type).

Template Parameters

Name

Description

ToQ

a target quantity type to which to cast the representation

Created with MrDocs