`mp_units::value_cast`¶

Explicit cast of a quantity's unit

Synopsis¶

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

template<auto ToU, typename FwdQ, RoundingPolicy Policy = truncated_t, Quantity Q = std::remove_cvref_t<FwdQ>>
  requires UnitOf<MP_UNITS_NTTP_TYPE(ToU), Q::quantity_spec> &&
           detail::ExplicitlyCastable<Q::unit, ToU, typename Q::rep> &&
           detail::ValidRoundingPolicyFor<Policy, typename Q::rep, typename Q::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.

auto d = value_cast<si::second>(1234 * ms); auto e = value_cast<si::second>(1567 * ms, rounded);

Return Value¶

Note

The return value should not be discarded.

Template Parameters¶

Name	Description
ToU	a unit to use for a target quantity

Parameters¶

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

mp_units::value_cast¶