`mp_units::value_cast`¶

Explicit cast of a quantity's representation

Synopsis¶

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

template<Quantity ToQ, typename FwdQ, RoundingPolicy Policy = truncated_t, Quantity Q = std::remove_cvref_t<FwdQ>>
  requires(ToQ::quantity_spec == Q::quantity_spec) && UnitOf<MP_UNITS_NONCONST_TYPE(ToQ::unit), Q::quantity_spec> &&
          std::constructible_from<typename ToQ::rep, typename Q::rep> &&
          detail::ExplicitlyCastable<Q::unit, ToQ::unit, typename ToQ::rep> &&
          detail::ValidRoundingPolicyFor<Policy, typename Q::rep, typename ToQ::rep>
[[nodiscard]] constexpr Quantity auto value_cast(FwdQ&& q, Policy = Policy{});

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).

Return Value¶

Note

The return value should not be discarded.

Template Parameters¶

Name	Description
ToQ	a target quantity type to which to cast the representation

Parameters¶

Name	Description
policy	an optional rounding policy (`truncated` when not provided)

mp_units::value_cast¶