Simple demo show how to use trait object for dynamic dispatch

trait_obj.rs

#![allow(dead_code)]
trait Bar {
    fn bar(&self) -> i32;
}
struct Foo{
    i:i32
}
impl Bar for Foo {
    fn bar(&self) -> i32{
     self.i
    }
}
fn baz ( t: Box<&dyn Bar>) -> i32 {
    t.bar() + 1 
}
#[test]
fn test() {
    let  foo = Foo{ i : 10}; 
    assert_eq!(10, foo.i);
    let d :&dyn Bar = &foo;
    let v1 = d.bar();
    let x = Box::new(d);
    let v2 = baz(x);
    assert_eq!(v1,10);
    assert_eq!(v2,11);
}