rust_programming_book 0.1.1

// https://www.ncameron.org/blog/dyn-trait-and-impl-trait-in-rust/
pub trait Animal {
    fn feed(&self) -> &str {
        "yerp"
    }

    fn make_noise(&self) {}

    fn lives_in(&self) {}
}

pub trait Herbivore {
    fn eats(&self) {}
}

#[allow(dead_code)]
#[derive(Debug)]
pub struct Dog {
    pub name: String,
    pub age: u8,
}
#[allow(dead_code)]
#[derive(Debug)]

pub struct Cow {
    pub name: String,
    pub weight: u8,
}
#[allow(dead_code)]
#[derive(Debug)]

pub struct Elephant {
    name: String,
    tusk_size: f32,
}

impl Animal for Dog {
    fn lives_in(&self) {
        println!("House");
    }
    fn make_noise(&self) {
        println!("whow!");
    }
}

impl Animal for Elephant {
    fn lives_in(&self) {
        println!("Forest");
    }
    fn make_noise(&self) {
        println!("Yawwww");
    }
}

impl Herbivore for Cow {
    fn eats(&self) {
        println!("grass");
    }
}

impl Herbivore for Elephant {
    fn eats(&self) {
        println!("milk and grass");
    }
}

// generic approach for impl
fn display_animal<T, U>(first: &T, second: &U)
where
    T: Animal + Herbivore,
    U: Herbivore,
{
    first.make_noise();
    first.lives_in();

    second.eats();
}
// impl approach
fn display_animal_second_approach(first: &(impl Animal + Herbivore), second: &impl Herbivore) {
    first.make_noise();
    first.lives_in();

    second.eats();
}
// dyn approach &(dyn Animal + Herbivore) is no possible)
fn display_animal_dyn_approach(first: &dyn Animal, second: &dyn Herbivore) {
    first.make_noise();
    first.lives_in();

    second.eats();
}

#[allow(dead_code)]
pub fn impl_dyn() {
    let dog = Dog {
        name: "Mike".to_string(),
        age: 2,
    };
    let cow = Cow {
        name: "Yak".to_string(),
        weight: 67,
    };

    let elephant = Elephant {
        name: "Ronaldo".to_string(),
        tusk_size: 2.1,
    };

    display_animal(&elephant, &cow);
    display_animal_second_approach(&elephant, &cow);

    display_animal_dyn_approach(&dog, &elephant);
}