class

fn main() {
    let mut monster: Mammal = MammalT::new();
    println!("monster's HP is {} and Hunger is {}", monster.hp, monster.hunger);
    monster.hunger = 15;
    monster.chkhunger();
    println!("monster's HP is {} and Hunger is {}", monster.hp, monster.hunger);
}

struct Mammal {
    hp: int,
    hunger: int
}

trait MammalT {
    fn new() -> Self;
    fn chkhunger(&mut self);
}

impl MammalT for Mammal {
    fn new() -> Mammal {
        Mammal { hp: 10, hunger: 0 }
    }
    fn chkhunger(&mut self) {
        if self.hunger > 10 {
            self.hp -= 1;
        }
    }
}