Flag interfaces

[hautajoki]

this pr adds support for flag interfaces not associated with any component data.

`// A component that stores data
interface Position {
    x: number;
    y: number;
}

// A flag (contains no data)
interface Alive extends Flag {}

const ball = spawn();

// Components with data must be assigned using set()
set<Position>(ball, { x: 10, y: 20 });

// @ts-expect-error: Cannot use add() with components that contain data
add<Position>(ball);

// @ts-expect-error: Cannot use set() with flag components
set<Alive>(ball, true);

// Tag components can only be added or removed
add<Alive>(ball);

// Flags can also be used  with spawn/insert functions
const cube = spawn<[Alive]>()

const torus = spawn()
insert<[Position, Alive]>([{ x: 10, y: 20 }])

[Ukendio]

I dont like that it is called a Flag and not a Tag. It doesnt really represent the same things. You can use Tags as flags for certain things, but can also be representative of symbolic state.

[Ukendio]

Just saw thiis but the first element is the predicate not the object.

[hautajoki]

The predicate here is a flamework generated key. pair<SomeComponent>(object)

[Ukendio]

Change the name of this interface and every subsequent dependents on this interface to use "Tag"

[hautajoki]

Tag is already used for Entity<.undefined>. Should I just get rid of that then?

[Ukendio]

Should I just get rid of that then?

Yeah, that sounds reasonable.