annotation
@Queries
@Queries(these: [Position, Velocity])
@Queries lets a handler declare the properties it operates on up front, and the compiler wraps the whole body in a query loop over the matching model instances. The body then runs once per match with each listed property bound by name — you write Position.column directly instead of opening a for (…) in query […] yourself — and self() gives the current instance. It takes the same shape as a manual query: these: [ … ] lists the required properties (each may carry a filter like Health{current <= 0}), and an optional on: Model restricts the match to instances of one model. Reach for it when a handler's entire job is "for every matching instance, do this"; drop to an explicit query when you need finer control inside the loop.
Example
program AdvanceMovement {
property Position { column: int = 0, row: int = 0 }
property Velocity { delta_x: int = 0, delta_y: int = 0 }
model Player { Position, Velocity }
@Queries(these: [Position, Velocity], on: Player) # body runs once per matching Player
handler AdvancePositions phase FixedUpdate {
Position.column = Position.column + Velocity.delta_x
Position.row = Position.row + Velocity.delta_y
}
handler SpawnPlayer phase Start {
spawn Player { Position { column: 0, row: 0 }, Velocity { delta_x: 1, delta_y: 0 } }
}
}