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[Merged by Bors] - Enable Constructing ReflectComponent/Resource #6257

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[Merged by Bors] - Enable Constructing ReflectComponent/Resource #6257

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fb37d6b
Enable Constructing ReflectComponent/Resource
zicklag Oct 14, 2022
d9f6046
Fix Typos in Doc Comments
zicklag Oct 14, 2022
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184 changes: 148 additions & 36 deletions crates/bevy_ecs/src/reflect.rs
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Expand Up @@ -17,14 +17,55 @@ use bevy_reflect::{
/// A [`ReflectComponent`] for type `T` can be obtained via
/// [`bevy_reflect::TypeRegistration::data`].
#[derive(Clone)]
pub struct ReflectComponent {
insert: fn(&mut World, Entity, &dyn Reflect),
apply: fn(&mut World, Entity, &dyn Reflect),
apply_or_insert: fn(&mut World, Entity, &dyn Reflect),
remove: fn(&mut World, Entity),
reflect: fn(&World, Entity) -> Option<&dyn Reflect>,
reflect_mut: unsafe fn(&World, Entity) -> Option<Mut<dyn Reflect>>,
copy: fn(&World, &mut World, Entity, Entity),
pub struct ReflectComponent(ReflectComponentFns);

/// The raw function pointers needed to make up a [`ReflectComponent`].
///
/// This is used when creating custom implementations of [`ReflectComponent`] with
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We should link to / explain the simpler way here. Ditto for the resource equivalent.

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Agreed. We should probably also include it in the docs for the constructors (e.g. ReflectComponent::new) as well, and indicate that this is almost certainly not needed unless you know what you're doing.

/// [`ReflectComponent::new()`].
///
/// > **Note:**
/// > Creating custom implementations of [`ReflectComponent`] is an advanced feature that most users
/// > will not need.
/// > Usually a [`ReflectComponent`] is created for a type by deriving [`Reflect`]
/// > and adding the `#[reflect(Component)]` attribute.
/// > After adding the component to the [`TypeRegistry`][bevy_reflect::TypeRegistry],
/// > it's [`ReflectComponent`] can then be retrieved when needed.
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///
/// Creating a custom [`ReflectComponent`] may be useful if you need to create new component types
/// at runtime, for example, for scripting implementations.
///
/// By creating a custom [`ReflectComponent`] and inserting it into a type's
/// [`TypeRegistration`][bevy_reflect::TypeRegistration],
/// you can modify the way that reflected components of that type will be inserted into the Bevy
/// world.
#[derive(Clone)]
pub struct ReflectComponentFns {
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Should these structs have their own ReflectComponentFns::new<T: Component>() -> Self functions to fill in the entire struct, allowing individual modification if needed? Or does it not make sense to only override some but not all function pointers?

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That's actually a good idea. I'm not 100% sure that there will be a use for overriding only some options, but it seems like it could happen.

/// Function pointer implementing [`ReflectComponent::insert()`].
pub insert: fn(&mut World, Entity, &dyn Reflect),
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Could you add a doc comment for each of these (same for ReflectResourceFns)? I imagine the people who do need this could benefit from knowing what they actually do.

/// Function pointer implementing [`ReflectComponent::apply()`].
pub apply: fn(&mut World, Entity, &dyn Reflect),
/// Function pointer implementing [`ReflectComponent::apply_or_insert()`].
pub apply_or_insert: fn(&mut World, Entity, &dyn Reflect),
/// Function pointer implementing [`ReflectComponent::remove()`].
pub remove: fn(&mut World, Entity),
/// Function pointer implementing [`ReflectComponent::reflect()`].
pub reflect: fn(&World, Entity) -> Option<&dyn Reflect>,
/// Function pointer implementing [`ReflectComponent::reflect_mut()`].
pub reflect_mut: unsafe fn(&World, Entity) -> Option<Mut<dyn Reflect>>,
/// Function pointer implementing [`ReflectComponent::copy()`].
pub copy: fn(&World, &mut World, Entity, Entity),
}

impl ReflectComponentFns {
/// Get the default set of [`ReflectComponentFns`] for a specific component type using its
/// [`FromType`] implementation.
///
/// This is useful if you want to start with the default implementation before overriding some
/// of the functions to create a custom implementation.
pub fn new<T: Component + Reflect + FromWorld>() -> Self {
<ReflectComponent as FromType<T>>::from_type().0
}
}

impl ReflectComponent {
Expand All @@ -34,7 +75,7 @@ impl ReflectComponent {
///
/// Panics if there is no such entity.
pub fn insert(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.insert)(world, entity, component);
(self.0.insert)(world, entity, component);
}

/// Uses reflection to set the value of this [`Component`] type in the entity to the given value.
Expand All @@ -43,7 +84,7 @@ impl ReflectComponent {
///
/// Panics if there is no [`Component`] of the given type or the `entity` does not exist.
pub fn apply(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.apply)(world, entity, component);
(self.0.apply)(world, entity, component);
}

/// Uses reflection to set the value of this [`Component`] type in the entity to the given value or insert a new one if it does not exist.
Expand All @@ -52,7 +93,7 @@ impl ReflectComponent {
///
/// Panics if the `entity` does not exist.
pub fn apply_or_insert(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.apply_or_insert)(world, entity, component);
(self.0.apply_or_insert)(world, entity, component);
}

/// Removes this [`Component`] type from the entity. Does nothing if it doesn't exist.
Expand All @@ -61,12 +102,12 @@ impl ReflectComponent {
///
/// Panics if there is no [`Component`] of the given type or the `entity` does not exist.
pub fn remove(&self, world: &mut World, entity: Entity) {
(self.remove)(world, entity);
(self.0.remove)(world, entity);
}

/// Gets the value of this [`Component`] type from the entity as a reflected reference.
pub fn reflect<'a>(&self, world: &'a World, entity: Entity) -> Option<&'a dyn Reflect> {
(self.reflect)(world, entity)
(self.0.reflect)(world, entity)
}

/// Gets the value of this [`Component`] type from the entity as a mutable reflected reference.
Expand All @@ -76,7 +117,7 @@ impl ReflectComponent {
entity: Entity,
) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: unique world access
unsafe { (self.reflect_mut)(world, entity) }
unsafe { (self.0.reflect_mut)(world, entity) }
}

/// # Safety
Expand All @@ -90,7 +131,7 @@ impl ReflectComponent {
world: &'a World,
entity: Entity,
) -> Option<Mut<'a, dyn Reflect>> {
(self.reflect_mut)(world, entity)
(self.0.reflect_mut)(world, entity)
}

/// Gets the value of this [`Component`] type from entity from `source_world` and [applies](Self::apply()) it to the value of this [`Component`] type in entity in `destination_world`.
Expand All @@ -105,18 +146,33 @@ impl ReflectComponent {
source_entity: Entity,
destination_entity: Entity,
) {
(self.copy)(
(self.0.copy)(
source_world,
destination_world,
source_entity,
destination_entity,
);
}

/// Create a custom implementation of [`ReflectComponent`].
///
/// This is an advanced feature,
/// useful for scripting implementations,
/// that should not be used by most users
/// unless you know what you are doing.
///
/// Usually you should derive [`Reflect`] and add the `#[reflect(Component)]` component
/// to generate a [`ReflectComponent`] implementation automatically.
///
/// See [`ReflectComponentFns`] for more information.
pub fn new(fns: ReflectComponentFns) -> Self {
Self(fns)
}
}

impl<C: Component + Reflect + FromWorld> FromType<C> for ReflectComponent {
fn from_type() -> Self {
ReflectComponent {
ReflectComponent(ReflectComponentFns {
insert: |world, entity, reflected_component| {
let mut component = C::from_world(world);
component.apply(reflected_component);
Expand Down Expand Up @@ -165,7 +221,7 @@ impl<C: Component + Reflect + FromWorld> FromType<C> for ReflectComponent {
})
}
},
}
})
}
}

Expand All @@ -174,20 +230,61 @@ impl<C: Component + Reflect + FromWorld> FromType<C> for ReflectComponent {
/// A [`ReflectResource`] for type `T` can be obtained via
/// [`bevy_reflect::TypeRegistration::data`].
#[derive(Clone)]
pub struct ReflectResource {
insert: fn(&mut World, &dyn Reflect),
apply: fn(&mut World, &dyn Reflect),
apply_or_insert: fn(&mut World, &dyn Reflect),
remove: fn(&mut World),
reflect: fn(&World) -> Option<&dyn Reflect>,
reflect_unchecked_mut: unsafe fn(&World) -> Option<Mut<dyn Reflect>>,
copy: fn(&World, &mut World),
pub struct ReflectResource(ReflectResourceFns);

/// The raw function pointers needed to make up a [`ReflectResource`].
///
/// This is used when creating custom implementations of [`ReflectResource`] with
/// [`ReflectResource::new()`].
///
/// > **Note:**
/// > Creating custom implementations of [`ReflectResource`] is an advanced feature that most users
/// > will not need.
/// > Usually a [`ReflectResource`] is created for a type by deriving [`Reflect`]
/// > and adding the `#[reflect(Resource)]` attribute.
/// > After adding the component to the [`TypeRegistry`][bevy_reflect::TypeRegistry],
/// > it's [`ReflectResource`] can then be retrieved when needed.
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///
/// Creating a custom [`ReflectResource`] may be useful if you need to create new resource types at
/// runtime, for example, for scripting implementations.
///
/// By creating a custom [`ReflectResource`] and inserting it into a type's
/// [`TypeRegistration`][bevy_reflect::TypeRegistration],
/// you can modify the way that reflected resources of that type will be inserted into the bevy
/// world.
#[derive(Clone)]
pub struct ReflectResourceFns {
/// Function pointer implementing [`ReflectResource::insert()`].
pub insert: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::apply()`].
pub apply: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::apply_or_insert()`].
pub apply_or_insert: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::remove()`].
pub remove: fn(&mut World),
/// Function pointer implementing [`ReflectResource::reflect()`].
pub reflect: fn(&World) -> Option<&dyn Reflect>,
/// Function pointer implementing [`ReflectResource::reflect_unchecked_mut()`].
pub reflect_unchecked_mut: unsafe fn(&World) -> Option<Mut<dyn Reflect>>,
/// Function pointer implementing [`ReflectResource::copy()`].
pub copy: fn(&World, &mut World),
}

impl ReflectResourceFns {
/// Get the default set of [`ReflectResourceFns`] for a specific resource type using its
/// [`FromType`] implementation.
///
/// This is useful if you want to start with the default implementation before overriding some
/// of the functions to create a custom implementation.
pub fn new<T: Resource + Reflect + FromWorld>() -> Self {
<ReflectResource as FromType<T>>::from_type().0
}
}

impl ReflectResource {
/// Insert a reflected [`Resource`] into the world like [`insert()`](World::insert_resource).
pub fn insert(&self, world: &mut World, resource: &dyn Reflect) {
(self.insert)(world, resource);
(self.0.insert)(world, resource);
}

/// Uses reflection to set the value of this [`Resource`] type in the world to the given value.
Expand All @@ -196,28 +293,28 @@ impl ReflectResource {
///
/// Panics if there is no [`Resource`] of the given type.
pub fn apply(&self, world: &mut World, resource: &dyn Reflect) {
(self.apply)(world, resource);
(self.0.apply)(world, resource);
}

/// Uses reflection to set the value of this [`Resource`] type in the world to the given value or insert a new one if it does not exist.
pub fn apply_or_insert(&self, world: &mut World, resource: &dyn Reflect) {
(self.apply_or_insert)(world, resource);
(self.0.apply_or_insert)(world, resource);
}

/// Removes this [`Resource`] type from the world. Does nothing if it doesn't exist.
pub fn remove(&self, world: &mut World) {
(self.remove)(world);
(self.0.remove)(world);
}

/// Gets the value of this [`Resource`] type from the world as a reflected reference.
pub fn reflect<'a>(&self, world: &'a World) -> Option<&'a dyn Reflect> {
(self.reflect)(world)
(self.0.reflect)(world)
}

/// Gets the value of this [`Resource`] type from the world as a mutable reflected reference.
pub fn reflect_mut<'a>(&self, world: &'a mut World) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: unique world access
unsafe { (self.reflect_unchecked_mut)(world) }
unsafe { (self.0.reflect_unchecked_mut)(world) }
}

/// # Safety
Expand All @@ -231,7 +328,7 @@ impl ReflectResource {
world: &'a World,
) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: caller promises to uphold uniqueness guarantees
(self.reflect_unchecked_mut)(world)
(self.0.reflect_unchecked_mut)(world)
}

/// Gets the value of this [`Resource`] type from `source_world` and [applies](Self::apply()) it to the value of this [`Resource`] type in `destination_world`.
Expand All @@ -240,13 +337,28 @@ impl ReflectResource {
///
/// Panics if there is no [`Resource`] of the given type.
pub fn copy(&self, source_world: &World, destination_world: &mut World) {
(self.copy)(source_world, destination_world);
(self.0.copy)(source_world, destination_world);
}

/// Create a custom implementation of [`ReflectResource`].
///
/// This is an advanced feature,
/// useful for scripting implementations,
/// that should not be used by most users
/// unless you know what you are doing.
///
/// Usually you should derive [`Reflect`] and add the `#[reflect(Resource)]` component
/// to generate a [`ReflectResource`] implementation automatically.
///
/// See [`ReflectResourceFns`] for more information.
pub fn new(&self, fns: ReflectResourceFns) -> Self {
Self(fns)
}
}

impl<C: Resource + Reflect + FromWorld> FromType<C> for ReflectResource {
fn from_type() -> Self {
ReflectResource {
ReflectResource(ReflectResourceFns {
insert: |world, reflected_resource| {
let mut resource = C::from_world(world);
resource.apply(reflected_resource);
Expand Down Expand Up @@ -285,7 +397,7 @@ impl<C: Resource + Reflect + FromWorld> FromType<C> for ReflectResource {
destination_resource.apply(source_resource);
destination_world.insert_resource(destination_resource);
},
}
})
}
}

Expand Down