Auto Singleton

The simplest singleton tool on the Asset Store. Add the [Singleton] attribute to any class and the asset handles everything: automatic asset generation, cleanup, and polymorphic access at runtime.

Features

  • Attribute-based setup: decorate any MonoBehaviour or ScriptableObject with [Singleton]: no base classes, no boilerplate; optional inherited, displayName, and folderPath arguments for fine-grained control
  • Automatic asset management: the editor creates and maintains prefabs (MonoBehaviour) or ScriptableObject assets after each compilation; deleting a singleton class also deletes its asset
  • Polymorphic access: retrieve all singletons assignable to a type via Singleton<T>.Instances; T can be a base class or an interface
  • Instance selection: designate which instance Singleton<T>.Instance returns using SelectInstance: by predicate, priority function, runtime type, direct reference, or no-arg when only one is registered
  • Safe access helpers: HasInstance and TryGetInstance let you check availability without catching exceptions; Find returns all instances matching a predicate
  • Manual registration: use Singleton.Add and Singleton.Remove at runtime to manage singletons of any reference type, not just Unity objects
  • No reload on play mode: works seamlessly with Unity’s no-domain-reload setting
  • Editor tooling: Top Bar menu with force-refresh, automatic refresh, change logging, and project icon toggles; singleton list inspector to view and enable/disable each singleton individually

Content

  • Singleton attribute: SingletonAttribute for automatic asset management, with inherited, displayName, and folderPath options
  • Runtime access classes: Singleton (manual Add / Remove) and Singleton<T> (Instance, Instances, HasInstance, TryGetInstance, Find, SelectInstance)
  • Editor tooling: automatic refresh system, singleton list inspector, project icons
  • Demo: a Tic Tac Toe game built with MVC, demonstrating 5 singletons across MonoBehaviour, ScriptableObject, and plain class types

Requirements

Unity 6.0 or later (tested up to 6.5)

Documentation

Documentation Public API

Get It

View on Unity Asset Store (Free)

Patch Notes

v1.2.0 June 5, 2026

Breaking Changes:

  • The singleton list asset has been renamed to Auto Singleton List and moved from Assets/Auto Singleton/Resources/ to Assets/Resources/. Existing projects must move it manually, or delete it and let it be recreated on the next refresh.
  • Singleton<T>.HasInstance now throws outside of play mode, consistent with Instance. Previously it silently returned false.
  • Singleton<T>.SelectInstance(Predicate<T>) now correctly returns false when no instance matches the predicate, instead of returning true and silently clearing the selected instance.

New:

  • Added Singleton<T>.TryGetInstance(out T instance): a non-throwing alternative to Instance that returns false when no instance is available, safe in both editor and builds.
  • SelectInstance overloads now log a warning in the editor when returning false, making misconfigured or missing setup easier to spot.
  • The Instance error message when no instance was selected now includes the count of available instances and a hint to call SelectInstance().
  • Newly created singleton assets are pinged in the Project window after a refresh.
  • The Auto Singleton List asset is automatically recreated if accidentally deleted.
  • The Auto Singleton root GameObject is now created lazily on the first MonoBehaviour singleton instantiation.
  • The singleton list ordering is now deterministic, preventing spurious VCS diffs on the Auto Singleton List asset.

Bug Fixes:

  • MonoBehaviour singleton components were not being saved to their prefab file correctly; they now are.
  • Open generic MonoBehaviour subclasses (e.g. class Foo<T> : MonoBehaviour) are no longer mistakenly treated as instantiable.
  • Singletons registered via Singleton.Add no longer appear as stale entries in the inspector after re-entering play mode.
  • SelectInstance with a numeric priority no longer incorrectly reports a tie when a singleton’s priority value equals int.MinValue or float.MinValue.
  • Singleton assets are now deleted through Unity’s asset pipeline, preventing stale references.
  • The singleton icon now scales correctly with the Project window’s zoom level.
  • Fixed path issues on Windows that could cause asset operations and the Documentation menu item to fail.
v1.1.0 January 23, 2026
  • The tool now fully works with no reload on play mode enabled
  • Can now add and remove singletons at runtime using new methods, Add and Remove, in the Singleton class
  • Removed the Find method from the Singleton class (it still exists in the Singleton<T> class)
  • Fixed a bug where singleton icons would not appear without an assembly reload
  • Fixed a bug happening if you launched the project with compilation errors
  • Demo and documentation modified to reflect those changes
v1.0.0 October 19, 2023

Initial release.