Crate bevy_register_in_world

Crate provides a way for tracking initialized to the world types, automatically initializing components into the world on add and conveniently adding system during runtime.

Motivation

Sometimes it’s impossible, or will be way too hard, to initialize everything on the stage of building the app.

For example:

 
#[derive(Component)]
struct GenericComponent<A, B>(A, B)
    where A: Send + Sync + 'static, B: Send + Sync + 'static;

fn system_operating_on_generic_component<A, B>(query: Query<&GenericComponent<A, B>>)
    where A: Send + Sync + 'static, B: Send + Sync + 'static 
{
    // do_something ...
}

Usual way to use generic types in bevy’s ecs is to provide a method to register all data, related to the generic parameter, to the world. For example, add_event registers all necessary data to the app so that it is possible to work with the registered event. This way of handling generics should still be preferred, because it avoids unnecessary runtime checks.

But in the situation above, for it to be possible, user should register every possible combination of two generics beforehand for the program to work. And situation gets progressively worse with the increase in amount of generics.

So, with this library you can do this:

use bevy_register_in_world::prelude::*;

#[derive(ComponentAutoRegister)]
struct GenericComponent<A, B>(A, B)
    where A: Send + Sync + 'static, B: Send + Sync + 'static;

impl<A, B> RegisterInWorld for GenericComponent<A, B> 
    where A: Send + Sync + 'static, B: Send + Sync + 'static
{
    fn register(mut world: DeferredWorld) {
        world.add_systems(Update, system_operating_on_generic_component::<A, B>);
    }
}
 
fn system_operating_on_generic_component<A, B>(query: Query<&GenericComponent<A, B>>) 
    where A: Send + Sync + 'static, B: Send + Sync + 'static
{
    // do_something ...
}

And when component with unique combination of generics is added, register is called during it’s on_add hook.

Modules

add_systems

Adding systems

app

Logic for app

component

Component stuff

prelude

Prelude module

Structs

RegisteredTypes

Stores a HashSet of types that were registered into the world using RegisterInWorld trait.

Traits

RegisterExtension

Trait that is implemented for world and app types for convenience of registering.

RegisterInWorld

Types that can be registered to the world.