Crate measures 

Set of declarative macros to define types to handle quantities provided of units of measurement, and optional uncertainty. The only macro to be used in application code is define_measure_types, which must be called at most once per module. It is recommended to be called only once per application. It is suggested to called it in a module named units.

Here is an extensive tutorial for the last version of the library.

Example of usage

mod units {
    measures::define_measure_types! {
        exact with_approx,
        scalar_properties [
            Time [
                Second {
                    suffix: " s",
                }
                Hour {
                    suffix: " h",
                    ratio: 3600.,
                }
            ]
        ]
        vector_properties [
            Length [
                Metre {
                    suffix: " m",
                }
                Foot {
                    suffix: " ft",
                    ratio: 0.3048,
                }
            ]
            Velocity [
                MetrePerSecond {
                    suffix: " m/s",
                }
            ]
        ]
        relationships [
            Metre 1 == MetrePerSecond 1 * Second 1,
        ]
    }
}

let l = units::Measure::<units::Metre, f32>::new(10000.);
assert_eq!(
    format!("{} = {}", l, l.convert::<units::Foot>()),
    "10000 m = 32808.4 ft",
);

let t = units::ApproxMeasure::<units::Second>::with_variance(5400., 0.81);
assert_eq!(
    format!("{} = {}", t, t.convert::<units::Hour>()),
    "5400 ± 0.9 s = 1.5 ± 0.00025 h",
);
let v = l.lossless_into::<f64>() / units::Measure::from(t);
assert_eq!(
    format!("{v}"),
    "1.8518518518518519 m/s",
);

Syntax of the macro define_measure_types!, in a kind of regular expression, where [] means “optional”, \[ and \] mean actual brackets, ()* means “repeat zero or more times”, | means “or”, and items included in the angle brackets < and > are identifiers, literals or expressions:

measures::define_measure_types! {
    [with_points]
    [with_directions]
    [with_2d]
    [with_3d]
    [with_transformations]
    [exact]
    [with_approx],
    [
    scalar_properties \[
        (
        <Name of a property> \[
            (
            <Name of a unit of measurement> {
                suffix: <string literal>,
                [
                ratio: <f64 const expression>,
                [offset: <f64 const expression>,]
                ]
            }
            )*
            \]
        )*
        \]
    ]
    [
    vector_properties \[
        (
        <Name of a property> \[
            (
            <Name of a unit of measurement> {
                suffix: <string literal>,
                [
                ratio: <f64 const expression>,
                ]
            }
            )*
            \]
        )*
        \]
    ]
    [
    vector_properties \[
        (
        <Name of a property> \[
            (
            <Name of a unit of measurement> {
                suffix: <string literal>,
                [
                ratio: <f64 const expression>,
                ]
            }
            )*
            \]
        )*
        \]
    ]
    [
    angle_measurement_units \[
        (
        <Name of a unit of measurement> {
            suffix: <string literal>,
            cycle_fraction: <f64 const expression>,
        }
        )*
    \]
    ]
    [
    relationships \[
        (
        <unit> 1 == <unit> 1 * __ 1,
        | <unit> 1 == <unit> 1 * <unit> 1,
        | <unit> 2 == <unit> 1 * <unit> 2,
        | <unit> 2 == <unit> 2 * <unit> 1,
        | <unit> 3 == <unit> 1 * <unit> 3,
        | <unit> 3 == <unit> 3 * <unit> 1,
        | <unit> 1 == <unit> 2 * __ 2,
        | <unit> 1 == <unit> 2 * <unit> 2,
        | <unit> 1 == <unit> 3 * __ 3,
        | <unit> 1 == <unit> 3 * <unit> 3,
        | <unit> 1 == <unit> 2 X __ 2,
        | <unit> 1 == <unit> 2 X <unit> 2,
        | <unit> 3 == <unit> 3 X __ 3,
        | <unit> 3 == <unit> 3 X <unit> 3,
        )*
    \]
    ]
}

Modules

angle

define_measure_types

define_units_relationship

dimensionless

inner

matrix_utils

test_utils

traits

Macros

angle_measurement_unit

assert_eq_32

assert_eq_64

assert_eq_tolerance

define_measure_types

define_measure_types_aux

define_scalar_property

define_units_relationship

define_vector_property

expand_1_1

expand_1_2

expand_1_3

expand_1_1_same

expand_2_2

expand_2_2_same

expand_3_3

expand_3_3_same

expand_cross_2

expand_cross_3

expand_cross_2_same

expand_cross_3_same

if_all_true

inner_define_affine_map_2d

inner_define_affine_map_3d

inner_define_approx_measure

inner_define_approx_measure_2d

inner_define_approx_measure_3d

inner_define_approx_measure_point

inner_define_approx_measure_point_2d

inner_define_approx_measure_point_3d

inner_define_linear_map_2d

inner_define_linear_map_3d

inner_define_measure

inner_define_measure_2d

inner_define_measure_3d

inner_define_measure_point

inner_define_measure_point_2d

inner_define_measure_point_3d

inner_define_signed_direction

inner_define_unsigned_direction

measurement_scalar_property

measurement_unit

measurement_unit_aux

measurement_vector_property