Specs example (https://github.com/slide-rs/specs)

specs-example.rs

extern crate specs;

use specs::Component;
use specs::VecStorage;
use specs::System;
use specs::WriteStorage;
use specs::ReadStorage;
use specs::World;
use specs::DispatcherBuilder;
use specs::RunNow;
use specs::Fetch;
use specs::Entities;
use specs::NullStorage;

#[derive(Debug)]
struct Vel(f32);

impl Component for Vel {
    type Storage = VecStorage<Self>;
}

#[derive(Debug)]
struct Pos(f32);

impl Component for Pos {
    type Storage = VecStorage<Self>;
}

#[derive(Debug, Default)]
struct Hero;

impl Component for Hero {
    type Storage = NullStorage<Self>;
}

struct SysA;

impl<'a> System<'a> for SysA {
    type SystemData = (Fetch<'a, DeltaTime>, Entities<'a>, WriteStorage<'a, Pos>, ReadStorage<'a, Vel>, ReadStorage<'a, Hero>);

    fn run(&mut self, (delta, entities, mut pos, vel, tag): Self::SystemData) {
        use specs::Join;

        println!("{:?}", *delta);

        for (entity, pos, vel, _) in (&*entities, &mut pos, &vel, !&tag).join() {
            match tag.get(entity) {
                Some(x) => panic!("{:?}", x),
                None => println!("None")
            }

            pos.0 += vel.0;
            println!("{:?}", pos);
            println!("{:?}", vel);
        }
    }
}

#[derive(Debug)]
struct DeltaTime(i32);

fn main() {
    let mut world = World::new();
    world.register::<Pos>();
    world.register::<Vel>();
    world.register::<Hero>();

    world.add_resource(DeltaTime(10));

    world.write_resource::<DeltaTime>().0 = 100;

    world.create_entity().with(Vel(2.0)).with(Pos(0.0)).build();
    world.create_entity().with(Vel(4.0)).with(Pos(1.6)).build();
    world.create_entity().with(Vel(1.5)).with(Pos(5.4)).with(Hero).build();

    world.create_entity().with(Pos(2.0)).build();

    let sys = SysA;

    let mut dispatcher = DispatcherBuilder::new().add(sys, "sys_a", &[]).build();

    dispatcher.dispatch(&world.res);

    //sys.run_now(&world.res);
}