Implement Display, LowerExp, UpperExp, ...

[iliekturtles]

https://doc.rust-lang.org/core/fmt/trait.Binary.html
https://doc.rust-lang.org/core/fmt/trait.Display.html
https://doc.rust-lang.org/core/fmt/trait.LowerExp.html
https://doc.rust-lang.org/core/fmt/trait.LowerHex.html
https://doc.rust-lang.org/core/fmt/trait.Octal.html
https://doc.rust-lang.org/core/fmt/trait.UpperExp.html
https://doc.rust-lang.org/core/fmt/trait.UpperHex.html

Is there a way to use the fmt syntax or flags to include an implicit unit conversion, unit abbreviation, or unit label?

// What replaces `...` to allow the following outputs: 10 m, 10 meters, 32.8084 ft, 32.8084 feet
println!("{...}", new Length(10, meter));

• Quantity
• $quantities (Dimension)
• BaseUnits
• $unit (Measurement units)

[iliekturtles]

Something like the following should be able to meet the requirements. Note that the following code takes a lot of liberties and is just to give an idea of what should be necessary.

The Arguments struct would contain uom specific formatting settings like the subunit to display and how to label the value. Numeric formatting options would still come from the format string and be pushed down to the underlying storage type's Display/LowerExp/... implementation.

mod fmt {
    pub struct Arguments<...> {
        subunit: Subunit,
        label: LabelEnum,
    }

    pub struct QuantityArguments<...> {
        quantity: Quantity<...>,
        arguments: Arguments,
    }

    impl Display for Arguments { ... }
    impl LowerExp for Arguments { ... }
    ...
}

...

let l = Length::<meter>::new(10);
let a1: Arguments = Arguments::new(meter, Abbreviation);
let a2: Arguments = Arguments::new(meter, Description);
let a3: QuantityArguments = Arguments::new(l, foot, Abbreviation);
let a4: QuantityArguments = Arguments::new(l, foot, Description);

// 10 m, 10 meters, 32.8084 ft, 32.8084 feet
println!("{}, {}, {}, {}", a1.with(l), a2.with(l), a3, a4);

[Aehmlo]

I have a working implementation that'll print a Quantity in any of the desired styles (with the unit appended in the desired format); do we need to be able to print raw units as well? If so, I'll write that and send a PR, but I'm not sure I see any use cases for that.

[iliekturtles]

Not exactly sure what you mean by printing raw units. Can you provide a short example?

[Aehmlo]

Something like println!("{}", meter), perhaps with the same options for the output to be "meter"/"m".

[iliekturtles]

Ahhh. Not needed! meter.abbreviation()/.singular()/.description() can be used.

[Aehmlo]

That's what I figured. PR inbound soon.