converter.rs

pub trait Converter {
  fn blah(&self) -> &String;
}

struct This {
  convert: String,
}
struct That {
  convert: String,
}

impl Converter for This { fn blah(&self) -> &String { &self.convert } }
impl Converter for That { fn blah(&self) -> &String { &self.convert } }

fn convert_to(s: &str) -> Option<Box<Converter+'static>> {
    match s {
        "this" => Some(Box::new(This {convert: "converted!".to_string()})),
        "that" => Some(Box::new(That {convert: "converted!".to_string()})),
        _ => None
    }
}

fn main() {
    let x = convert_to("this").unwrap();
    let y = convert_to("that").unwrap();
    println!("{:?}", x.blah());
    println!("{:?}", y.blah());
}