ambassador 0.5.1

Trait implementation delegation via procedural macros
Documentation 
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extern crate ambassador;

use ambassador::{delegatable_trait, Delegate};

#[delegatable_trait]
pub trait Shout {
    fn shout(&self, input: &str) -> String;
}

pub struct Cat;

impl Shout for Cat {
    fn shout(&self, input: &str) -> String {
        format!("{} - meow!", input)
    }
}

pub struct Dog;

impl Shout for Dog {
    fn shout(&self, input: &str) -> String {
        format!("{} - wuff!", input)
    }
}

#[derive(Delegate)]
#[delegate(Shout, target = "bar")]
pub struct WrappedAnimals<A: Shout> {
    foo: Cat,
    bar: A,
}

pub fn main() {
    let foo_animal = WrappedAnimals { foo: Cat, bar: Cat };
    println!("{}", foo_animal.shout("BAR"));
    let bar_animal = WrappedAnimals { foo: Cat, bar: Dog };
    println!("{}", bar_animal.shout("BAR"));
}