Generic Class Factory

GenericClass.cs

using System.Reflection;

namespace GenericInitialiserTest
{
    public static class GenericClassFactory
    {
        public static readonly Dictionary<Type, Type> Classes = new();

        public static void RegisterAllGenerics(Assembly assembly)
        {
            var types = assembly.GetTypes();
            foreach (var type in types)
            {
                var bt = type.BaseType;
                if (bt != null)
                {
                    if (bt.IsGenericType &&
                        bt.GetGenericTypeDefinition() == typeof(GenericClass<>))
                    {
                        var innerTypes = bt.GetGenericArguments();

                        if (innerTypes.Length == 1)
                            Register(innerTypes[0], type);
                    }
                }
            }
        }

        public static void Register(Type innerType, Type genericClass)
        {
            if (Classes.ContainsKey(innerType))
                throw new InvalidProgramException($"Duplicate GenericClass for type: {innerType}");

            Classes.Add(innerType, genericClass);

            Console.WriteLine($"Reigstered for type: {innerType}");
        }

        // This just returns the Type - could be updated to create a new instance instead
        public static Type? GetGenericClassFor<T>()
        {
            if (Classes.TryGetValue(typeof(T), out var t))
                return t;

            return null;
        }
    }

    public abstract class GenericClass<T>
    {
        private readonly T _instance;
        public T Instance => _instance;

        internal GenericClass(T instance)
        {
            _instance = instance;
        }
    }

}

Impls.cs

namespace GenericInitialiserTest
{
    class GenericFloat : GenericClass<float>
    {
        public GenericFloat(float f) : base(f) { }
    }

    class GenericString : GenericClass<string>
    {
        public GenericString(string s) : base(s) { }
    }
}

Program.cs

using GenericInitialiserTest;
using System.Reflection;

// Can register either current assembly or loaded assemblies (such as external DLLs)
GenericClassFactory.RegisterAllGenerics(Assembly.GetExecutingAssembly());

GenericFloat f = new(4.5f);

Console.WriteLine($"Class for float  = {GenericClassFactory.GetGenericClassFor<float>()}");
Console.WriteLine($"Class for string = {GenericClassFactory.GetGenericClassFor<string>()}");