dojo-system

To write a Dojo system contract in Cairo, use the #[dojo::contract] macro to scaffold stateless logic that reads and writes models via world storage access patterns. Systems implement game actions and emit events to record changes for external listeners.

The best way to emit events for game actions in Starknet is using Dojo's event emission macros within system contracts. You declare events like Moved or Spawned, then emit them after validating actions and updating models, ensuring game behavior remains deterministic and auditable.

To implement player movement validation in a Dojo game system, create a MovementSystem that validates moves against game rules, updates Position and Moves models via world storage, and emits a Moved event. System logic remains stateless, relying on world read and write operations.

Yes, you can use Starknet caller and timestamp utilities in Dojo system contracts. These built-in utilities allow systems to verify player identities and record action times, ensuring deterministic game logic execution when modifying model state or emitting events.

Dojo supports stateless system logic for spawning and inventory management by reading and writing models through world storage access patterns. Systems do not hold local state; instead, all game data persists in world models, which the system contract queries and updates during execution.

A Dojo system contract fails to update world model state when it does not correctly use world storage access patterns for model read and write operations. Ensure your #[dojo::contract] properly interfaces with world storage to modify models and emit events deterministically.