test.rs

use std::string::String;
trait MyToStr {
  fn my_to_str(s: &Self) -> String;
}
struct Foo {
  name : String
}

impl MyToStr for Foo {
  fn my_to_str(s : &Foo) -> String {
    s.name.clone() + " from Foo"
  }
}
struct Bar {
  name : String
}

impl MyToStr for Bar {
  fn my_to_str(s : &Bar) -> String {
    s.name.clone() + " from Bar"
  }
}
fn main(){
  let f = Foo {name : String::from_str("Foo")};
  let b = Bar {name : String::from_str("Bar")};
  let fs = MyToStr::my_to_str(&f);
  let bs = MyToStr::my_to_str(&b);
  println!("String is {}", fs);
  println!("String is {}", bs);
}