use std::any::Any;
use std::boxed::Box;
use std::ops::Index;

#[derive(Debug)]
pub struct Test {
    a: u64,
    b: String
}

impl Index<&str> for Test {
    type Output = Box<dyn Any>;

    fn index(&self, val: &str) -> &Self::Output {
        match val{
            "a" => &Box::new(self.a),
            "b" => &Box::new(self.b),
            _ => unreachable!()
        }
    }
}

fn main() {
    let x = Test { a: 1, b: String::from("2")};
    println!("{:?}", x["b"]);
}