hecs-component-provider

Easily define behavior for sets of components when using the hecs ECS library.

```rust use hecscomponentprovider::{ defaulttraitimpl, gentuplequerycomponentproviders, ComponentProvider, ComponentProviderMut };

struct Position(f32, f32); struct Velocity(f32, f32);

// implement a behavior for all entities that provide the required components

[defaulttraitimpl]

trait Update: ComponentProviderMut + ComponentProvider { fn update(&mut self, dt: f32) { let &Velocity(vx, vy) = self.get(); let position: &mut Position = self.get_mut(); position.0 += vx * dt; position.1 += vy * dt; } }

let mut world = hecs::World::new(); world.spawn((Position(1.0, 2.0), Velocity(0.7, 0.8)));

// prepare a query that returns entities with the components required for the Update behavior gentuplequerycomponentproviders!( Query, (&mut Position, &Velocity) );

let dt = 0.1; for (, mut entity) in world.querymut::() { // apply the Update behavior to the entity entity.update(dt);

let position = entity.0;
assert_eq!(position.0, 1.07);
assert_eq!(position.1, 2.08);

} ```