Injector.cs

using System;
using System.Collections.Generic;
using Assets.Scripts.Core;
using UnityEngine;
using Object = UnityEngine.Object;

public class Inject : Attribute { }

public class Controller
{
	public Controller()
	{
		Injector.Inject(this);
		Updater.Add(this);
	}
}

public class Injector
{
	static Dictionary<Type, object> objects = new Dictionary<Type, object>();

	public static T Get<T>()
	{
		return (T) Get(typeof(T));
	}

	static object Get(Type type)
	{
		object obj;

		objects.TryGetValue(type, out obj);

		if(obj == null)
		{
			if(typeof(Object).IsAssignableFrom(type))
			{
				obj = Object.FindObjectOfType(type);
				Debug.Assert(obj != null, "Couldn't find view for " +type);
			}
			else
			{
				obj = Activator.CreateInstance(type);
			}
			objects[type] = obj;
		}

		return obj;
	}

	public static void Inject(object obj)
	{
		foreach (var field in obj.GetType().GetFieldsWithAttribute<Inject>())
		{
			var fieldObj = Get(field.FieldType);
			field.SetValue(obj, fieldObj);
		}
	}

	public static void Clear()
	{
		objects.Clear();
	}
}