Guidance for a Rust newbie - Decimal constant?

[nwillc-paxos]

Given:

fn percent_change(prior: Decimal, current: Decimal) -> Decimal {
    (current - prior) / prior * Decimal::from(100)
}

Is there a way to have a Decimal::ONE_HUNDRED constant?

[schungx]

I would second this, as it is usually quite convenient to have the following constants, in addition to ZERO, ONE, TWO and PI:

NEGATIVE_ONE (useful as a step)
TEN
HUNDRED (useful for percentage calculations), can be simulated via TEN * TEN
THOUSAND (useful for K calculations), can be simulated via TEN * TEN * TEN
HALF_PI (useful as a 90-deg angle), can be simulated via PI / TWO
TWO_PI (useful as a full circle), can be simulated via PI * TWO
E (useful for scientific)

[c410-f3r]

It is currently possible to create a constant Decimal through the from_parts method.

const DECIMAL_0_001: Decimal = Decimal::from_parts(1, 0, 0, false, 3);

Once rust-lang/rust#51999 is stabilized, it will be possible to write

const PI: Decimal = Decimal::try_from_i128_with_scale(3141_i128, 3).unwrap();

[schungx]

Yes, but in actual usage, it is simpler to just do Dynamic::TEN without having to remember to first create the TEN const somewhere...