Derive Macro strum::EnumCount

#[derive(EnumCount)]
{
    // Attributes available to this derive:
    #[strum]
}

Add a constant usize equal to the number of variants.

For a given enum generates implementation of strum::EnumCount, which adds a static property COUNT of type usize that holds the number of variants.

use strum::{EnumCount, IntoEnumIterator};
use strum_macros::{EnumCount as EnumCountMacro, EnumIter};

#[derive(Debug, EnumCountMacro, EnumIter)]
enum Week {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
}

assert_eq!(7, Week::COUNT);
assert_eq!(Week::iter().count(), Week::COUNT);