Policy that checks the value is within [min, max]and reports violations.

Synopsis

template<Quantity Q>
struct check_in_range;

Description

If the quantity's representation type has a constraint_violation_handler specialization, the handler's on_violation() is called on out-of-bounds values (providing guaranteed enforcement regardless of build mode). Otherwise, falls back to MP_UNITS_EXPECTS, which may be disabled in release builds.

Example:

{cpp}
 // With constrained<double, throw_policy> rep → throws std::domain_error on violation
 // With plain double rep → asserts via MP_UNITS_EXPECTS (may be no-op in release)
 inline constexpr struct equator final :
     absolute_point_origin<geo_latitude, check_in_range{-90 * deg, 90 * deg}> {} equator;