Singleton

AchEngine provides three singleton implementations for cases where DI is not suitable.

Prefer ServiceLocator + AchEngineInstaller when possible. Singletons make testing and dependency tracking harder.

Singleton<T> — Pure C# Singleton

Thread-safe (double-checked locking), no MonoBehaviour required.

public class AnalyticsService : Singleton<AnalyticsService>
{
    protected override void OnInitialized() { }
    public void Track(string eventName) { }
}

AnalyticsService.Instance.Track("level_start");

MonoSingleton<T> — Scene-local Singleton

Destroyed when the scene changes.

public class LobbyController : MonoSingleton<LobbyController> { }

PersistentMonoSingleton<T> — Persistent Singleton

Survives scene transitions via DontDestroyOnLoad.

public class GameSession : PersistentMonoSingleton<GameSession>
{
    public string PlayerId { get; private set; }
}