Bloody traits and traitorous traits....

gistfile1.txt

trait MustHave {}


trait First: MustHave {}
trait Second: MustHave {}

trait Final: MustHave {}

impl Final for dyn First {}
impl Final for dyn Second {}

struct A{}
impl MustHave for A{}
struct B{}
impl MustHave for B{}
struct C{}
impl MustHave for C{}

impl First for A{}
impl Second for B{}
impl Final for C{}


fn cast_a(f: Box<dyn First>) -> Box<dyn Final> {
    let d: Box<dyn Final> = f;
    d
}


fn makeit() -> (Box<dyn Final>, Box<dyn Final>, Box<dyn Final>) {
    let a = A{};
    let b = B{};
    let c = C{};
    (Box::new(a) as Box<dyn First>, Box::new(b), Box::new(c))
}

fn main() {
    println!("Hello, world!");
}