annotation
@EngineSystem
"@EngineSystem(Component, Phase) function esys_name() { … }"
@EngineSystem(Component, Phase) marks a function as an engine-owned system: the compiler adds it to the engine-system registry, and the frame loop calls it every Phase — after the game's own handlers — whenever the named Component is present in the program. It is the package-declarable form of the built-in engine systems (the ones that advance SpriteAnim/Motion/Light2D), so a third-party controller ships a system the same way the standard library does, with no compiler edit. The function reads and writes components by name through the reflection ABI, so it stays layout-independent and additive: a build that never declares the component compiles byte-for-byte the same. Phases are Input, FixedUpdate, Update, LateUpdate and Render.
Example
program EngineSystemDemo {
property Score { value: int = 0 }
model Player { Score }
@EngineSystem(Score, Update) function esys_score() -> void { # runs every Update
let P = world_prop_id("Score")
let e = world_query_next(P, 0)
if e >= 0 { world_set(e, P, 0, world_get(e, P, 0) + 1) } # advance by name
}
@OnSpawn(Player) handler Init { }
handler Boot phase Start { let e = world_spawn(world_model_id("Player")) }
handler Run phase Update {
let P = world_prop_id("Score")
print(world_get(world_query_next(P, 0), P, 0)) # grows each frame
quit()
}
}