How to clone a boxed closure

help
25

Sorry to bother, I read @leudz 's code at Rust Playground again and fixed the problem using box

use std::rc::Rc;
use std::collections::HashMap;

trait FnClone: Fn(usize, usize) -> usize {
    fn clone_box(&self) -> Box<dyn FnClone>;
}

impl<T> FnClone for T
where
    T: 'static + Fn(usize, usize) -> usize + Clone,
{
    fn clone_box(&self) -> Box<dyn FnClone> {
        Box::new(self.clone())
    }
}

impl Clone for Box<dyn FnClone> {
    fn clone(&self) -> Self {
        (**self).clone_box()
    }
}

fn main() {
    let mut h = HashMap::new();

    let add1: Box<dyn FnClone> = Box::new(|a: usize, b: usize| -> usize {
        a + b
    });
    let add2: Box<dyn FnClone> = Box::new(|a: usize, b: usize| -> usize {
        a + b + 1
    });

    h.insert("add1", add1);
    h.insert("add2", add2);

    let mut engine = Engine::default();

    for (_name, f) in h.iter() {
        let f1 = f.clone();
        engine.register_fn(f1);
    }
    println!("len={}", engine.fs.len());
}

#[derive(Default)]
pub struct Engine {
    pub fs: Vec<Rc<Fn(usize, usize) -> usize>>
}
impl Engine {
    pub fn register_fn(&mut self, f: impl Fn(usize, usize)->usize + 'static) {
        self.fs.push(Rc::new(f));
    }
}

This code compiles, but it uses box and treated a closure as a trait FnClone, not very simple. Can my code above get fixed while still using Rc?