absolute_unit 0.11.4

A unit system for Rust's type system to catch unit errors in your physical calculations.
Documentation 
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use crate::{
    DynamicUnits, LengthUnit, Real, TimeUnit, Velocity, impl_value_type_conversions,
    supports_absdiffeq, supports_cancellation, supports_quantity_ops, supports_scalar_ops,
    supports_shift_ops, supports_value_type_conversion,
};
use std::{fmt, fmt::Debug, marker::PhantomData};

// While there is no "meaning" to this unit, traditionally, it shows up in _so many_ places
// that having a way to represent it as an intermediate is extremely useful to avoid dynamic
// analysis of unit types (and associated .as_dyn() line noise).
#[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "bevy_reflect", derive(bevy_reflect::Reflect))]
pub struct VelocitySquared<UnitLength: LengthUnit, UnitTime: TimeUnit> {
    v: Real,
    #[cfg_attr(feature = "serde", serde(skip))]
    #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
    phantom_1: PhantomData<UnitLength>,
    #[cfg_attr(feature = "serde", serde(skip))]
    #[cfg_attr(feature = "bevy_reflect", reflect(ignore))]
    phantom_2: PhantomData<UnitTime>,
}
supports_quantity_ops!(VelocitySquared<A, B>, LengthUnit, TimeUnit);
supports_shift_ops!(VelocitySquared<A1, B1>, VelocitySquared<A2, B2>, LengthUnit, TimeUnit);
supports_scalar_ops!(VelocitySquared<A, B>, LengthUnit, TimeUnit);
supports_cancellation!(VelocitySquared<A1, B1>, VelocitySquared<A2, B2>, LengthUnit, TimeUnit);
supports_absdiffeq!(VelocitySquared<A, B>, LengthUnit, TimeUnit);
supports_value_type_conversion!(VelocitySquared<A, B>, LengthUnit, TimeUnit, impl_value_type_conversions);

impl<L, T> fmt::Display for VelocitySquared<L, T>
where
    L: LengthUnit,
    T: TimeUnit,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.v.0, f)?;
        write!(f, "{}^2/{}^2", L::UNIT_SHORT_NAME, T::UNIT_SHORT_NAME)
    }
}

impl<L, T> VelocitySquared<L, T>
where
    L: LengthUnit,
    T: TimeUnit,
{
    pub fn sqrt(&self) -> Velocity<L, T> {
        Velocity::<L, T>::from(self.v.sqrt())
    }

    pub fn as_dyn(&self) -> DynamicUnits {
        DynamicUnits::new2o2::<L, L, T, T>(self.v)
    }
}

impl<'a, LA, TA, LB, TB> From<&'a VelocitySquared<LA, TA>> for VelocitySquared<LB, TB>
where
    LA: LengthUnit,
    TA: TimeUnit,
    LB: LengthUnit,
    TB: TimeUnit,
{
    fn from(v: &'a VelocitySquared<LA, TA>) -> Self {
        let length_ratio = Real(LA::METERS_IN_UNIT / LB::METERS_IN_UNIT);
        let time_ratio = Real(TB::SECONDS_IN_UNIT / TA::SECONDS_IN_UNIT);
        Self {
            v: v.v * length_ratio * length_ratio * time_ratio * time_ratio,
            phantom_1: PhantomData,
            phantom_2: PhantomData,
        }
    }
}

// impl<LA, TA, TB> Mul<Time<TB>> for VelocitySquared<LA, TA>
// where
//     LA: LengthUnit,
//     TA: TimeUnit,
//     TB: TimeUnit,
// {
//     type Output = Velocity<LA, TA>;
//
//     fn mul(self, other: Time<TB>) -> Self::Output {
//         Velocity::<LA, TA>::from(self.v.0 * Time::<TA>::from(&other).f64())
//     }
// }

#[cfg(test)]
mod test {
    use crate::meters_per_second;
    use approx::assert_abs_diff_eq;

    #[test]
    fn test_velocity_squared() {
        let a = meters_per_second!(1f64);
        let b = meters_per_second!(1f64);
        assert_abs_diff_eq!(
            (a * a + b * b).sqrt(),
            meters_per_second!(1.414),
            epsilon = 0.001
        );
    }
}