Rust shared structs.

playground.rs

trait Fruit {
    fn who_am_i(&self) -> String;
}

struct Apple {
    name: String,
}
struct Banana {
    name: String,
    color: String,
}

impl Fruit for Apple {
    fn who_am_i(&self) -> String {
        format!("I am '{}'", self.name)
    }
}

impl Fruit for Banana {
    fn who_am_i(&self) -> String {
        format!("I am '{} {}'", self.color , self.name)
    }
}

fn apple() -> impl Fruit {
    Apple { 
        name: "Apple".to_string(),
    }
}

fn banana() -> impl Fruit {
    Banana {
        name: "Banana".to_string(),
        color: "green".to_string(),
    }
}

fn foods() -> Vec< Box<Fruit> > {
    vec![Box::new(apple()), Box::new(banana()), Box::new(banana())]
}

fn main() {
    println!("{}", apple().who_am_i());
    println!("{}", banana().who_am_i());
    
    println!("foods: ");
    for fruit in foods().into_iter() {
        println!("{}", fruit.who_am_i() )
    }
}