ComponentId

ComponentId

1. usize

Description

A value which uniquely identifies the type of a [Component] or [Resource] within a [World].

Each time a new Component type is registered within a World using e.g. [World::register_component] or [World::register_component_with_descriptor] or a Resource with e.g. [World::init_resource], a corresponding ComponentId is created to track it.

While the distinction between ComponentId and [TypeId] may seem superficial, breaking them into two separate but related concepts allows components to exist outside of Rust's type system. Each Rust type registered as a Component will have a corresponding ComponentId, but additional ComponentIds may exist in a World to track components which cannot be represented as Rust types for scripting or other advanced use-cases.

A ComponentId is tightly coupled to its parent World. Attempting to use a ComponentId from one World to access the metadata of a Component in a different World is undefined behavior and must not be attempted.

Given a type T which implements [Component], the ComponentId for T can be retrieved from a World using [World::component_id()] or via [Components::component_id()]. Access to the ComponentId for a [Resource] is available via [Components::resource_id()].

Functions