Access to singleton instance fails with derived class

Question

I have a database wrapper code like this (pseudo code):

class MyDBWrapper<objecttype> : Singleton
{
    private DBDriver _Driver

    Driver => Instance._Driver; 

    ... tons of static functionality here referencing the driver
}

and then I can create custom databases from it:

class ObjectA_DB : MyDBWrapper<ObjectA_Type>
{
    ... all my calls using the static functionalities of the base class
}

this works very well...

Now, comes a different scenario:

I have a generic object: BaseObject and a bunch of derived objects: ObjectA, ObjectB, etc

and they all require the same database code, so I did that:

class MyGenericDB<T> : MyDBWrapper<T> where T : BaseObject
{
    .. common functionality
} 

and then instantiated the type specific classes like this:

class MyTypeA_DB : MyGenericDB<ObjectA_Type>
class MyTypeB_DB : MyGenericDB<ObjectB_Type>

and this compiles properly, however the singleton code is causing problem when I try to access the instance as it seems like it's recursing. Visual studio is unable to give a proper error as to what happens, but it hangs then crashes, so I am guessing a stack overflow.

The singleton code is here:

public abstract class Singleton<T> where T : class
{
    private static readonly Lazy<T> _Instance = new Lazy<T>(CreateInstanceOfT, LazyThreadSafetyMode.PublicationOnly);
    protected static T Instance => _Instance.Value;
    private static T CreateInstanceOfT()
    {
        return Activator.CreateInstance(typeof(T), true) as T;
    }
}

Did I miss anything obvious?

Answer 1

Not that used to this version of generics as my main work is in unity, and they update their core every decade, but I am pretty sure that you need your instance to be public to be allowed to read it.

When I write this, I traditionally create a private static instance of the passed type, and follow that up with a public static access function that creates that type if it does not yet exist.

A good full example for my own main engine can be found here: http://wiki.unity3d.com/index.php/Singleton .