Rust でぽりもーふぃずむった

trait でオブジェクト指向っぽいことをしよう

use std::io;

trait Animal {
  fn get_num(&self) -> u64;
}

struct Cat {
  num: u64,
}

struct Dog {
  num: u64,
}

impl Animal for Cat {
  fn get_num(&self) -> u64 {
    println!("Cat");
    self.num
  }
}

impl Animal for Dog {
  fn get_num(&self) -> u64 {
    println!("Dog");
    self.num
  }
}

fn main() {
    println!("1:Cat, 2:Dog");
    let mut input = String::new();
    io::stdin().read_line(&mut input).expect("failed");
    let input = input.trim();

    let cat = Cat{num: 1};
    let dog = Dog{num: 2};

    let animal: &dyn Animal = match input.as_ref() {
      "1" => &cat as &dyn Animal,
      "2" => &dog as &dyn Animal,
      _=> panic!("error"),
    };

    println!("num: {}", animal.get_num());
}