mp_units::value_cast

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_REMOVE_CONST(decltype(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)