Trait components_arena::ComponentClass

pub trait ComponentClass {
    // Required method
    fn token() -> &'static ComponentClassToken
       where Self: Sized;
}

An utility trait describing a specific component type.

Normally for a non-generic component type the component type itself implements ComponentClass.

For generic components it would be difficult to have an own ComponentClassToken instance for every specialization because Rust does not have “generic statics” feature.

So, if some component type X is generic, normally you should introduce common non-generic uninhabited type XComponent and implement ComponentClass for this synthetic type.

Correct implementation should return reference to the one and same ComponentClassToken instance from the token function. Also it should be guaranteed that no other ComponentClass implementation returns same ComponentClassLock instance. This requirements can be easily satisfied with private static:

struct MyComponent { /* ... */ }

impl ComponentClass for MyComponent {
    fn token() -> &'static ComponentClassToken {
        static TOKEN: ComponentClassToken = ComponentClassToken::new();
        &TOKEN
    }
}

Required Methods

fn token() -> &'static ComponentClassTokenwhere Self: Sized,

Essential for components arena internal mechanic.

Implementors