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pub struct Handle<T> where
    T: Asset
{ pub id: HandleId, /* private fields */ }
Expand description

A handle into a specific Asset of type T.

Handles contain a unique id that corresponds to a specific asset in the Assets collection.

Accessing the Asset

A handle is not the asset itself, but should be seen as a pointer to the asset. Modifying a handle’s id only modifies which asset is being pointed to. To get the actual asset, try using Assets::get or Assets::get_mut.

Strong and Weak

A handle can be either “Strong” or “Weak”. Simply put: Strong handles keep the asset loaded, while Weak handles do not affect the loaded status of assets. This is due to a type of reference counting. When the number of Strong handles that exist for any given asset reach zero, the asset is dropped and becomes unloaded. In some cases, you might want a reference to an asset but don’t want to take the responsibility of keeping it loaded that comes with a Strong handle. This is where a Weak handle can be very useful.

For example, imagine you have a Sprite component and a Collider component. The Collider uses the Sprite’s image size to check for collisions. It does so by keeping a Weak copy of the Sprite’s Strong handle to the image asset.

If the Sprite is removed, its Strong handle to the image is dropped with it. And since it was the only Strong handle for that asset, the asset is unloaded. Our Collider component still has a Weak handle to the unloaded asset, but it will not be able to retrieve the image data, resulting in collisions no longer being detected for that entity.

Fields

id: HandleId

The ID of the asset as contained within its respective Assets collection

Implementations

Creates a weak handle into an Asset identified by id.

Recasts this handle as a weak handle of an Asset U.

Returns true if this is a weak handle.

Returns true if this is a strong handle.

Makes this handle Strong if it wasn’t already.

This method requires the corresponding Assets collection.

Creates a weak copy of this handle.

Creates an untyped copy of this handle.

Creates a weak, untyped copy of this handle.

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Executes the destructor for this type. Read more

ECS WorldQuery to fetch the components to extract.

Filters the entities with additional constraints.

Defines how the component is transferred into the “render world”.

Converts to this type from the input type.

Converts to this type from the input type.

Converts to this type from the input type.

Converts to this type from the input type.

Converts to this type from the input type.

Converts to this type from the input type.

Converts to this type from the input type.

Constructs a concrete instance of Self from a reflected value.

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Returns the type name of the underlying type.

Returns the TypeInfo of the underlying type. Read more

Returns the value as a Box<dyn Any>.

Returns the value as a &dyn Any.

Returns the value as a &mut dyn Any.

Casts this type to a reflected value

Casts this type to a mutable reflected value

Clones the value as a Reflect trait object. Read more

Performs a type-checked assignment of a reflected value to this value. Read more

Applies a reflected value to this value. Read more

Returns an enumeration of “kinds” of type. Read more

Returns a mutable enumeration of “kinds” of type. Read more

Returns a “partial equality” comparison result. Read more

Returns a hash of the value (which includes the type). Read more

Debug formatter for the value. Read more

Returns a serializable version of the value. Read more

Returns a reference to the value of the field named name as a &dyn Reflect. Read more

Returns a mutable reference to the value of the field named name as a &mut dyn Reflect. Read more

Returns a reference to the value of the field with index index as a &dyn Reflect. Read more

Returns a mutable reference to the value of the field with index index as a &mut dyn Reflect. Read more

Returns the name of the field with index index.

Returns the number of fields in the struct.

Returns an iterator over the values of the struct’s fields.

Clones the struct into a DynamicStruct.

Returns the compile-time info for the underlying type. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Return the T ShaderType for self. When used in AsBindGroup derives, it is safe to assume that all images in self exist. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait. Read more

Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait. Read more

Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s. Read more

Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s. Read more

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait. Read more

Compare self to key and return true if they are equal.

Returns the argument unchanged.

Creates Self using data from the given World

Returns a reference to the value of the field named name, downcast to T. Read more

Returns a mutable reference to the value of the field named name, downcast to T. Read more

Returns a reference to the value specified by path. Read more

Returns a mutable reference to the value specified by path. Read more

Returns a statically typed reference to the value specified by path.

Returns a statically typed mutable reference to the value specified by path. Read more

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more