Example usage vector with objects witch implemented common trait

trait.rs

trait Figure {
    fn area(&self) -> f64;
}

struct Circle {
    radius: f64,
}

struct Rectangle {
    a: f64,
    b: f64,
}

struct Square {
    a: f64,
}

impl Figure for Circle {
    fn area(&self) -> f64 {
        self.radius * self.radius * 3.14
    }
}

impl Figure for Square {
    fn area(&self) -> f64 {
        self.a * self.a
    }
}

impl Figure for Rectangle {
    fn area(&self) -> f64 {
        todo!()
    }
}

fn main() {
    let figures: Vec<Box<dyn Figure>> = vec![
        Box::new(Circle{radius:1.0}),
        Box::new(Square{a:2.0}), 
        Box::new(Rectangle{a:1.0, b:2.0}),
    ];

    for figure in figures.iter() {
        println!("{}", figure.area())
    }