F5QxDpCP

1trait Spec {
2    fn key(&self) -> &str;
3    fn compute_big_number(&self) -> i32;
4}
5
6trait Resolver {
7    fn resolve<S: Spec>(&self, spec: S) -> i32;
8}
9
10fn display<R: Resolver>(r: &R) {
11    struct MySpec;
12    impl Spec for MySpec {
13        fn key(&self) -> &str {
14            "hmmm"
15        }
16        fn compute_big_number(&self) -> i32 {
17            for i in 1..10 {
18                // gee this sure is taking a long time
19            }
20            99
21        }
22    }
23    let spec: MySpec = MySpec {};
24    println!("{}", r.resolve(spec));
25}
26
27fn main() {
28    let secret_key: &str = "awhooga";
29    struct Z;
30    impl Resolver for Z {
31        fn resolve<S: Spec>(&self, spec: S) -> i32 {
32            if spec.key() != secret_key {
33                4
34            } else {
35                spec.compute_big_number()
36            }
37        }
38    }
39    display(&Z {});
40}