Unity singleton

info.md

Singleton adapted for Unity needs

 

Notes

Simple tu use and foolproof. It uses abstraction to make it almost invisible on your code and easy to reuse it.

 

Usage

1. Inherid on your class:

    public class MyMonoBehaviour : Singleton<MyMonoBehaviour>
    {
        public bool ExampleBool;
    }

2. Call it from another script:

    MyMonoBehaviour.Instance.ExampleBool;

Same instructions for SingletonPersistent.cs

 

Compatibility

• Any Unity version
• Any pipeline (Build-in, URP, HDRP, etc)

 

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Singleton.cs

using UnityEngine;

public abstract class Singleton<T> : MonoBehaviour where T : MonoBehaviour
{
    public static T Instance { get; private set; }

    protected virtual void Awake()
    {
        CheckSingleton();
    }

    public virtual bool CheckSingleton()
    {
        // Check if base and derived classes are the same type
        if (this is not T)
        {
            Debug.LogError($"Base and derived classes are different types:\n\t- Base: {typeof(T)}\n\t- Derived: {GetType()}\nPlease modify {typeof(T)}\nDestroying the component in <b>{name}</b>.");
            Destroy(this);
            return false;
        }

        // Check if this instance is a duplicated
        if (Instance != null && Instance != this)
        {   
            if (this.gameObject.GetComponents<Component>().Length <= 2)
            {
                Debug.LogWarning($"Multiple instances of <b>{GetType().Name}</b>\nDestroying the gameobject <b>{name}</b>.");
                Destroy(this.gameObject);
            }
            else
            {
                Debug.LogWarning($"Multiple instances of <b>{GetType().Name}</b>\nDestroying the component in <b>{name}</b>.");
                DestroyImmediate(this); // Instant destruction to avoid waiting for the end of the frame.
            }
            return false;
        }

        // Set this instance as the selected
        Instance = this as T;
        return true;
    }
}

SingletonPersistent.cs

using UnityEngine;

public abstract class Singleton<T> : MonoBehaviour where T : MonoBehaviour
{
    public static T Instance { get; private set; }

    protected virtual void Awake()
    {
        CheckSingleton();
    }

    public virtual bool CheckSingleton()
    {
        // Check if base and derived classes are the same type
        if (this is not T)
        {
            Debug.LogError($"Base and derived classes are different types:\n\t- Base: {typeof(T)}\n\t- Derived: {GetType()}\nPlease modify {typeof(T)}\nDestroying the component in <b>{name}</b>.");
            Destroy(this);
            return false;
        }

        // Check if this instance is a duplicated
        if (Instance != null && Instance != this)
        {
            Debug.LogWarning($"Multiple instances of <b>{GetType().Name}</b>\nDestroying the component in <b>{name}</b>.");
            Destroy(this);
            return false;
        }

        // Set this instance as the selected
        Instance = this as T;
        return true;
    }
}