Macro components_arena::Component

macro_rules! Component {
    (
        ()
        $vis:vis enum $name:ident $($body:tt)+
    ) => { ... };
    (
        ()
        $vis:vis struct $name:ident $($body:tt)+
    ) => { ... };
    (
        (class=$class:ident)
        $vis:vis enum $name:ident
        < $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ $(,)?>
        $($body:tt)+
    ) => { ... };
    (
        (class=$class:ident)
        $vis:vis struct $name:ident
        < $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ $(,)?>
        $($body:tt)+
    ) => { ... };
    (
        @impl [$name:ident]
    ) => { ... };
    (
        @impl <> [$vis:vis] [$name:ident] [$class:ident] [ $($g:tt)+ ] [ $($r:tt)+ ]
    ) => { ... };
}

Macro attribute for deriving Component trait.

Examples

Non-generic component

macro_attr! {
    #[derive(Component!)]
    struct Item { /* ... */ }
}

static ITEM: ComponentClassMutex<Item> = ComponentClassMutex::new();

// ...

let mut arena = Arena::new(&mut ITEM.lock().unwrap());
let id = arena.insert(|id| (Item { /* ... */ }, id));

Generic component

macro_attr! {
    #[derive(Component!(class=ItemComponent))]
    struct Item<T> {
        context: T
    }
}

static ITEM: ComponentClassMutex<ItemComponent> = ComponentClassMutex::new();

// ...

let mut arena_u8 = Arena::new(&mut ITEM.lock().unwrap());
let _ = arena_u8.insert(|id| (Item { context: 7u8 }, id));

let mut arena_u32 = Arena::new(&mut ITEM.lock().unwrap());
let _ = arena_u32.insert(|id| (Item { context: 7u32 }, id));