fruit.rs

use std::io;

trait Fruit {
    fn get_size(&self) -> f32;
}

struct Apple {
    size: f32,
}

struct Pine {
    size: f32,
}

impl Fruit for Apple {
    fn get_size(&self) -> f32 {
        self.size
    }
}

impl Fruit for Pine {
    fn get_size(&self) -> f32 {
        self.size
    }
}

fn main() {
    let stdin = io::stdin();
    let mut input = String::new();
    let _ = stdin.read_line(&mut input);

    let apple = Apple { size: 80.0 };
    let pine = Pine { size: 100.0 };

    let data = input.trim();
    let fruit: &dyn Fruit = match data {
        "1" => &apple,
        "2" => &pine,
        _ => panic!("error!"),
    };
    println!("size: {}", fruit.get_size());
}