How to pass argument to the functions called using clokwerk library - rust

Question

The following is MVP of what I am doing
use std::sync::Arc;
use clokwerk::Interval::*;
use clokwerk::TimeUnits;
use std::time::Duration;
use std::thread;
#[derive(Clone, Debug)]
pub struct Person {
pub name: String,
pub age: u16,
}
pub fn print_debug_person(person_arc: Arc<Person>) {
println!("Person is :{:?}", person_arc)
}
fn main() {
let p = Person { name: "Asnim".to_string(), age: 10 };
let p = Arc::new(p);
let mut scheduler = clokwerk::Scheduler::new();
for loop_period in 1..5 {
let person_arc = p.clone();
scheduler.every(loop_period.seconds()).run(move || print_debug_person(person_arc));
}
loop {
scheduler.run_pending();
thread::sleep(Duration::from_millis(10));
}
}
Here the code fails with error
error[E0507]: cannot move out of `person_arc`, a captured variable in an `FnMut` closure
--> src/main.rs:27:79
|
26 | let person_arc = p.clone();
| ---------- captured outer variable
27 | scheduler.every(loop_period.seconds()).run(move || print_debug_person(person_arc));
| ^^^^^^^^^^ move occurs because `person_arc` has type `Arc<Person>`, which does not implement the `Copy` trait
What am I doing wrong here. What change should I make so that arc can be passed to this function?
Isn't Arc the right structure to use?
I wont able able add Copy trait to the struct as String doesn't implement Copy trait. Right?
Dependencies
clokwerk = "0.3.5"

Answer 1

The function print_debug_person takes ownership of the value given to it, so calling it with person_arc will attempt to move it. However, since the closure is intended to be called multiple times, this would leave the value invalid for future calls.
To fix this, you can either make a new Arc<Person> each time by cloning it:
scheduler.every(loop_period.seconds()).run(move || print_debug_person(person_arc.clone()));
Or, since your function doesn't seem to need ownership, it should just borrow the Person:
pub fn print_debug_person(person: &Person) {
println!("Person is :{:?}", person)
}
Which you can call with a &Arc<Person> due to deref coercion:
scheduler.every(loop_period.seconds()).run(move || print_debug_person(&person_arc));