Module quantities.compiletime

Example

import quantities.compiletime;
import quantities.si;
import std.format : format;
import std.math : approxEqual;

// Introductory example
{
    // Use the predefined quantity types (in module quantities.si)
    Volume volume;
    Concentration concentration;
    Mass mass;

    // Define a new quantity type
    alias MolarMass = typeof(kilogram / mole);

    // I have to make a new solution at the concentration of 5 mmol/L
    concentration = 5.0 * milli(mole) / liter;

    // The final volume is 100 ml.
    volume = 100.0 * milli(liter);

    // The molar mass of my compound is 118.9 g/mol
    MolarMass mm = 118.9 * gram / mole;

    // What mass should I weigh?
    mass = concentration * volume * mm;
    assert(format("%s", mass) == "5.945e-05 [M]");
    // Wait! That's not really useful!
    assert(siFormat!"%.1f mg"(mass) == "59.5 mg");
}

// Working with predefined units
{
    auto distance = 384_400 * kilo(meter); // From Earth to Moon
    auto speed = 299_792_458 * meter / second; // Speed of light
    auto time = distance / speed;
    assert(time.siFormat!"%.3f s" == "1.282 s");
}

// Dimensional correctness is check at compile-time
{
    Mass mass;
    assert(!__traits(compiles, mass = 15 * meter));
    assert(!__traits(compiles, mass = 1.2));
}

// Calculations can be done at compile-time
{
    enum distance = 384_400 * kilo(meter); // From Earth to Moon
    enum speed = 299_792_458 * meter / second; // Speed of light
    enum time = distance / speed;
    /* static */
    assert(time.siFormat!"%.3f s" == "1.282 s");
    // NB. Phobos can't format floating point values at run-time.
}

// Create a new unit from the predefined ones
{
    auto inch = 2.54 * centi(meter);
    auto mile = 1609 * meter;
    assert(mile.value(inch).approxEqual(63_346)); // inches in a mile
    // NB. Cannot use siFormatter, because inches are not SI units
}

// Create a new unit with new dimensions
{
    // Create a new base unit of currency
    auto euro = unit!(double, "C"); // C is the chosen dimension symol (for currency...)

    auto dollar = euro / 1.35;
    auto price = 2000 * dollar;
    assert(price.value(euro).approxEqual(1481)); // Price in euros
}

// Compile-time parsing
{
    enum distance = si!"384_400 km";
    enum speed = si!"299_792_458 m/s";
    assert(is(typeof(distance) == Length));
    assert(is(typeof(speed) == Speed));
}

// Run-time parsing of statically typed Quantities
{
    auto data = ["distance-to-the-moon" : "384_400 km", "speed-of-light" : "299_792_458 m/s"];
    auto distance = parseSI!Length(data["distance-to-the-moon"]);
    auto speed = parseSI!Speed(data["speed-of-light"]);
}