trait_object_example.rs

fn main() {
    let xs: Vec<Box<dyn PrintableNumber>> = vec![Box::new(Foo), Box::new(Bar)];
    print_each(xs);
}

struct Foo;
struct Bar;

// Combined trait that requires both ToString and ToInt
trait PrintableNumber: ToString + ToInt {}

// Implement the combined trait for any type that implements both component traits
impl<T: ToString + ToInt> PrintableNumber for T {}

trait ToString {
    fn to_string(&self) -> String;
}

impl ToString for Foo {
    fn to_string(&self) -> String {
        "Foo".to_string()
    }
}

impl ToString for Bar {
    fn to_string(&self) -> String {
        "Bar".to_string()
    }
}

trait ToInt {
    fn to_int(&self) -> i32;
}

impl ToInt for Foo {
    fn to_int(&self) -> i32 {
        42
    }
}

impl ToInt for Bar {
    fn to_int(&self) -> i32 {
        24
    }
}

fn print_each(xs: Vec<Box<dyn PrintableNumber>>) {
    for x in xs {
        println!("{}", x.to_string());
        println!("{}", x.to_int());
    }
}