Execution Order - s&box Documentation

Execution Order

Understanding the order in which component methods are called.

Flowchart

Component lifecycle follows a specific order:

1. Constructor — Object created
2. OnAwake — First initialization (once)
3. OnEnabled — Component becomes active
4. OnStart — Scene is ready
5. OnUpdate — Every frame
6. OnFixedUpdate — Physics timestep
7. OnDisabled — Component deactivated
8. OnDestroy — Cleanup

Order Within Stages

Within each stage, components execute in order:

1. By default, execution order is undefined
2. Use [Order(int)] attribute to control:

[Order( 100 )]
public class EarlyComponent : Component { }

[Order( 500 )]
public class LateComponent : Component { }

Lower numbers execute first.

GameObjectSystem Order

Systems also have execution stages:

public class MySystem : GameObjectSystem
{
    public MySystem( Scene scene ) : base( scene )
    {
        ListenToStage( Stage.Startup, 0, OnStartup );
        ListenToStage( Stage.Update, 100, OnUpdate );
    }
}

Best Practices

• Use [Order()] sparingly
• Don't rely on execution order between unrelated components
• Use events/messages for cross-component communication
• Initialize in OnAwake, start logic in OnStart

Common Mistakes

• Assuming components update in creation order
• Doing heavy work in constructors
• Not handling disabled state properly
• Cross-component dependencies without proper ordering