Crate enum_display_derive

derive Display for simple enums

You can derive the Display trait for simple enums.

Actually, the most complex enum definition that this crate supports is like this one:

#[derive(Display)]
pub enum FooBar {
    Foo,
    Bar(),
    FooBar(i32), // some wrapped type which implements Display
}

The above code will be expanded (roughly, without the enum definition) into this code:

impl Display for FooBar {
    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::result::Result<(), ::std::fmt::Error> {
        match *self {
            FooBar::Foo => f.write_str("Foo"),
            FooBar::Bar => f.write_str("Bar()"),
            FooBar::FooBar(ref inner) => ::std::fmt::Display::fmt(inner, f),
        }
    }
}

Examples

#[macro_use]
extern crate enum_display_derive;

use std::fmt::Display;

#[derive(Display)]
enum FizzBuzz {
   Fizz,
   Buzz,
   FizzBuzz,
   Number(u64),
}

fn fb(i: u64) {
   match (i % 3, i % 5) {
       (0, 0) => FizzBuzz::FizzBuzz,
       (0, _) => FizzBuzz::Fizz,
       (_, 0) => FizzBuzz::Buzz,
       (_, _) => FizzBuzz::Number(i),
   }
}

fn main() {
   for i in 0..100 {
       println!("{}", fb(i));
   }
}