Styjun

• situation

I want to implement a generic-based 'PoolingManagerBase' in a singleton pattern for class pooling.

• Question

Why is it that a class that inherits from 'PoolingManagerBase' does not create a component that contains a singleton instance?

• Configuration

First, I implement the generic-based 'Singleton' class.

The 'Singleton' class code looks like this

public abstract class Singleton<T> : CComponent where T : CComponent

 private static T _Instance = null;

 public static T Instance
 
 get
 
 if (_Instance == null)
 
 GameObject gObject = new GameObject(typeof(T).ToString());
 _Instance = gObject.AddComponent<T>();

 DontDestroyOnLoad(gObject);
 
 return _Instance;
 
 

 public static T Create() => Instance;

Items are also held in the form of 'PoolingItemBase' and scoped to ITEM as below

public class PoolingItemBase where ITEM : PoolingItemBase<ITEM>

Therefore, the item manager also scopes ITEM as below

public class PoolingManagerBase <ITEM>: Singleton <PoolingManagerBase<ITEM>> where ITEM : PoolingItemBase<ITEM>

• apply

To actually use it, we construct the child class as shown below.

public class TempItem : PoolingItemBase<TempItem>

public class TempItemManager : PoolingManagerBase<TempItem>

• result

Singleton's

_Instance = gObject.AddComponent<T>();

Null is returned in part

I've been shoveling for two days, but I do not have a pointy reason ...

Is there a limit to writing nested generics in Unity?

--------------- EDIT ---------------

1. To distinguish it from the existing Unity Component, I replaced the Singleton inherited Component with CComponent




2. Below is the code for the CComponent class

public abstract class CComponent : MonoBehaviour

 [HideInInspector] public Transform _Transform = null;
 [HideInInspector] public Rigidbody _Rigidbody = null;
 [HideInInspector] public Rigidbody2D _Rigidbody2D = null;

 public virtual void Awake()
 
 _Transform = transform;
 _Rigidbody = GetComponentInChildren<Rigidbody>();
 _Rigidbody2D = GetComponentInChildren<Rigidbody2D>();
 

 public virtual void Update() 
 public virtual void FixedUpdate() 
 public virtual void LateUpdate() 

3. It seems to have come to an answer after thinking about the painful time.
   When I added _Instance via AddComponent<T>() inside Singleton, the type I actually imported came with information about <T>, not the lowest class.
   We just learned that Unity does not support generic-based components, so the above code did not work.
   So I modified the Singleton with the following code.

public abstract class Singleton<T> : CComponent where T : MonoBehaviour

 private static T _Instance = null;
 private static Type _InstanceType = null;

 public static T Instance
 
 get
 
 if (_Instance == null)
 
 GameObject gObject = new GameObject(typeof(T).ToString());
 _Instance = gObject.AddComponent(_InstanceType) as T;

 DontDestroyOnLoad(gObject);
 
 return _Instance;
 
 

 public static T Create(Type tType)
 
 _InstanceType = tType;
 return Instance;
 

I had the inconvenience of going through Create(typeof(T)), but now it's working well.