scene_api.rs

use std::cell::{Ref, RefCell, RefMut};
use std::collections::HashMap;
use std::rc::Rc;

pub trait MyTrait {
    fn get_id(&self) -> i32;
    fn print_message(&self);
    fn mut_message(&mut self, String);
}

#[derive(Default)]
pub struct Object {
    message: String,
    id: i32,
}

impl Object {
    pub fn new(id: i32) -> Object {
        Object {
            id,
            message: String::from("\"Default message\""),
            ..Default::default()
        }
    }
}

impl MyTrait for Object {
    fn get_id(&self) -> i32 {
        self.id
    }
    fn print_message(&self) {
        println!("Object {}: {}", self.id, self.message);
    }

    fn mut_message(&mut self, message: String) {
        self.message = message
    }
}

#[derive(Default)]
pub struct Scene {
    objects: HashMap<i32, Rc<RefCell<MyTrait>>>,
}

impl Scene {
    pub fn new() -> Scene {
        Scene {
            ..Default::default()
        }
    }

    pub fn add(&mut self, object: impl MyTrait + 'static) -> i32 {
        let id = object.get_id();
        self.objects
            .insert(id.clone(), Rc::new(RefCell::new(object)));
        id
    }

    pub fn get(&self, id: &i32) -> Ref<MyTrait + 'static> {
        self.objects
            .get(id)
            .map(|x| x.borrow())
            .expect("Object Not found")
    }

    pub fn get_mut(&mut self, id: &i32) -> RefMut<MyTrait + 'static> {
        self.objects
            .get_mut(id)
            .map(|x| x.borrow_mut())
            .expect("Object Not found")
    }
}

fn main() {
    let mut scene = Scene::new();

    let id_0 = scene.add(Object::new(0));
    let id_1 = scene.add(Object::new(1));
    let id_2 = scene.add(Object::new(2));

    let s = scene.get(&id_0);
    s.print_message();

    let w = scene.get(&id_1);
    w.print_message();

    let z = scene.get_mut(&id_2);
    z.print_message();
}