Struct oxygengine_core::ecs::EntityBuilder

#[must_use = "Please call .build() on this to finish building it."]
pub struct EntityBuilder<'a> {
    pub entity: Entity,
    pub world: &'a World,
    // some fields omitted
}

The entity builder, allowing to build an entity together with its components.

Examples

use specs::{prelude::*, storage::HashMapStorage};

struct Health(f32);

impl Component for Health {
    type Storage = HashMapStorage<Self>;
}

struct Pos {
    x: f32,
    y: f32,
}

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

let mut world = World::new();
world.register::<Health>();
world.register::<Pos>();

let entity = world
    .create_entity() // This call returns `EntityBuilder`
    .with(Health(4.0))
    .with(Pos { x: 1.0, y: 3.0 })
    .build(); // Returns the `Entity`

Distinguishing Mandatory Components from Optional Components

use specs::{prelude::*, storage::HashMapStorage};

struct MandatoryHealth(f32);

impl Component for MandatoryHealth {
    type Storage = HashMapStorage<Self>;
}

struct OptionalPos {
    x: f32,
    y: f32,
}

impl Component for OptionalPos {
    type Storage = DenseVecStorage<Self>;
}

let mut world = World::new();
world.register::<MandatoryHealth>();
world.register::<OptionalPos>();

let mut entitybuilder = world.create_entity().with(MandatoryHealth(4.0));

// something trivial to serve as our conditional
let include_optional = true;

if include_optional == true {
    entitybuilder = entitybuilder.with(OptionalPos { x: 1.0, y: 3.0 })
}

let entity = entitybuilder.build();

Fields

entity: Entity

The (already created) entity for which components will be inserted.

world: &'a World

A reference to the World for component insertions.

Trait Implementations

impl<'a> Builder for EntityBuilder<'a>

pub fn with<T>(self, c: T) -> EntityBuilder<'a> where
    T: Component, 

Inserts a component for this entity.

If a component was already associated with the entity, it will overwrite the previous component.

pub fn build(self) -> Entity

Finishes the building and returns the entity. As opposed to LazyBuilder, the components are available immediately.

impl<'a> Drop for EntityBuilder<'a>

pub fn drop(&mut self)

Executes the destructor for this type.