# Callbacks and values [Back to Python](https://rustic-game-engine.pages.dev/markdown/scripting/python.md). Supported lifecycle names are `on_create`, `on_start`, `on_enable`, `fixed_update`, `update`, `on_disable`, `on_destroy`, and `on_stop`. Only frame callbacks receive `dt` (seconds). Omitted callbacks are handled automatically. C and C++ register function pointers in `RusticBehavior`; Python passes a callback dictionary to `run`; PHP passes one to `rustic_run`; C# and Java dispatch the supplied callback name. Luau returns a table and also accepts `Start`, `FixedUpdate`, `Update`, and the other capitalized lifecycle aliases used by Lua. State declared outside callbacks persists for this behavior instance until teardown or reload. Python and PHP use native dictionaries/arrays for key state. C#, Java, and C use native action structs/objects with `.held`. Luau uses tables and returns translation as three separate numbers. C property/attribute reads return `RusticValue`: inspect its `type` and use `boolean`, `number`, `string`, or `vector`/`length`. C strings and read values last until the next callback; copy them if you need to retain them. C# property/attribute reads return ordinary `object?` values (bool, long/double, string, double[] or null); Java returns Object values (Boolean, Long/Double, String, double[] or null). Cast to the declared property type before arithmetic. C scene listing takes a path argument, e.g. `Game.scene.List("Game.scene")`, and returns a `RusticList` with count/items.