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Injector

public class Injector : Singleton<Injector>

A lightweight runtime dependency injection (DI) system tailored for Unity, supporting [Inject] and [Provide] attributes. The Injector finds and resolves dependencies via reflection at runtime startup, simplifying cross-component references and modular game architecture.

If you wish to inject after the first-time setup of the Injector during runtime, derive from ISelfRegisteredInjectionTarget and call Injector.CollectSelfRegisteredInjectable(this) in your Awake() method.

Overview​

  • Purpose: Automatically inject dependencies into MonoBehaviour components marked with [Inject], and collect dependencies from IDependencyProvider methods marked with [Provide].
  • Lifecycle: Executes early via DefaultExecutionOrder(-3000) to ensure dependencies are wired before most game logic begins.

Attributes​

InjectAttribute​

Usage: Apply to fields or methods.
Target: Field, Method
Purpose: Declares a dependency that should be automatically resolved and injected at runtime.

ProvideAttribute​

Usage: Apply to methods.
Target: Method
Purpose: Registers the returned value as a resolvable dependency in the injection registry.

Interfaces​

IDependencyProvider​

Marker interface to identify provider MonoBehaviours containing [Provide] methods.

IInjectorReceivable​

Components implementing this interface will have their InjectionCompleted() method called after all injections are performed.

Functionality​

Initialization (Awake)​

  • Scans scene for all MonoBehaviours implementing IDependencyProvider.
  • Registers each [Provide] method's return value into a DI registry.
  • Injects all [Inject] fields and methods for discovered components.
  • Queues and injects any ISelfRegisteredInjectionTarget collected pre-initialization.

Injection Logic (Inject)​

  • Resolves and assigns instances to fields marked with [Inject].
  • Invokes methods marked with [Inject], passing resolved arguments.
  • Calls InjectionCompleted() on any IInjectorReceivable.

Public Methods​

CollectSelfRegisteredInjectable(ISelfRegisteredInjectionTarget target)​

Adds a component to the injection queue if injection hasn’t started yet, otherwise injects immediately.

Internal Mechanics​

  • Binding Flags: Uses BindingFlags.Instance | Public | NonPublic to access all eligible fields/methods.
  • Resolution: Matches field/method parameter types against the internal registry of provided instances.

Dependencies & Integration​

  • Designed to work seamlessly with GameStateManager, where [Inject] is used to resolve MultiplayerService, GameServiceFactory, and more.

Usage Example​

[Inject]
private MultiplayerService _multiplayer;

[Inject]
void Init(GameServiceFactory factory)
{
    _factory = factory;
}
[Provide]
public GameOrchestrator GetGameOrchestrator() => orchestrator;

Hook this into your architecture and your MonoBehaviours will magically receive what they need—no more FindObjectOfType() spaghetti!