Function and Closure references as values in struct

fns_and_closures_in_structs.rs

/// Demonstrates an approach for accepting different types of functions, with different lifetimes
///  as struct values.

type MyFn = dyn Fn();

struct ContainsFns<'a> {
    other_fn: &'a MyFn,
    fns: Option<Vec<&'a MyFn>>
}

trait RunsFns {
    fn run_fns(&self);
}

impl RunsFns for ContainsFns<'_> {
    fn run_fns(&self) {
        (self.other_fn)();
        self.fns.as_deref().map(|fns| fns.into_iter().for_each(|f| f()));
    }
}

fn hello() {
    println!("Hello 1");
}

fn main() {
    let fn_one = || println!("Hello 1.2");
    let fn_two = || println!("Hello 1.3");

    let t = ContainsFns {
        other_fn: &hello,
        fns: None,
    };

    let t2 = ContainsFns {
        other_fn: &fn_two,
        fns: Some(vec![
            &hello,
            &fn_one,
            &fn_two,
            &|| println!("Hello 1.4")
        ])
    };

    t.run_fns();
    t2.run_fns();
    hello();
}