MonoSingleton.cs

MonoSingleton.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UnityEngine;

namespace LiquidPools {
/// use
/// public class NewClass : MonoSingleton<NewClass> { }
    [DefaultExecutionOrder(-999)]
    public abstract class MonoSingleton<T>: MonoBehaviour where T: MonoSingleton<T> {
        public enum MonoSingletonDuplicateBehaviour {
            DestroyOldInstance,
            DestroyNewInstance,
            DisableOldInstance
        };
        public MonoSingletonDuplicateBehaviour duplicateBehavior = MonoSingletonDuplicateBehaviour.DestroyOldInstance;
        public static string GameObjectName {
            get {
                return Instance.gameObject.name;
            }
        }
        private static T _instance;
        public static bool IsInstanced {
            get {
                return _instance != null;
            }
        }
        public static T Instance {
            get {
                return _instance;
            }
            private set {
                _instance = value;
            }
        }
        
        protected void Awake() {
            if (Instance!=null) {
                Debug.LogError($"MonoSingleton An instance of {Instance.GetType().ToString()} already exists named {Instance.gameObject.name}; {duplicateBehavior}", Instance);

                switch(duplicateBehavior) {
                    case MonoSingletonDuplicateBehaviour.DestroyOldInstance:
                        Destroy(Instance.gameObject);
                        break;
                    case MonoSingletonDuplicateBehaviour.DestroyNewInstance:
                        Destroy(this.gameObject);
                        return;
                    case MonoSingletonDuplicateBehaviour.DisableOldInstance:
                        Instance.gameObject.SetActive(false);
                        break;
                    default:
                        break;
                }
                //return;
            }
            Debug.Log($"MonoSingleton<{typeof(T)}> Awake named {gameObject.name}", this);
            Instance = (T)this;
            AfterAwake();
        }
        protected void OnDestroy() {
            Debug.Log($"MonoSingleton<{typeof(T)}> Destroying  {gameObject.name}", this);
            Instance = null;
            AfterOnDestroy();
        }
        /// Override this method to implement Awake functionality
        protected virtual void AfterAwake() {
        
        }
        /// Override this method to implement OnDestroy functionality
        protected virtual void AfterOnDestroy() {

        }
    }
}