C# Smart Enum Pattern - Part 3: Advanced generic class

ISmartEnumValue.cs

public interface ISmartEnumValue
{
    int Id { get; }
}

OrderStatus.cs

public record OrderStatusValue(int Id, string Description) : ISmartEnumValue;

public class OrderStatus : SmartEnum<OrderStatusValue, OrderStatus>
{
    public static readonly OrderStatusValue Pending = Register(new(1, "Pending"));
    public static readonly OrderStatusValue Shipped = Register(new(2, "Shipped"));
}

ProductStatus.cs

public record ProductStatusValue(int Id, string Description) : ISmartEnumValue;

public class ProductStatus : SmartEnum<ProductStatusValue, ProductStatus>
{
    public static readonly ProductStatusValue Pending = Register(new(1, "Pending"));
    public static readonly ProductStatusValue Available = Register(new(2, "Available"));
    public static readonly ProductStatusValue OutOfStock = Register(new(3, "Out of Stock"));
}

Program.cs

public class Program
{
    public static void Main()
    {
        // Initialize once at startup (e.g., Program.cs)
        ProductStatus.Initialize();

        // Example 1: Strict access (Expects ID to exist)
        var status = ProductStatus.Get(1); 
        Console.WriteLine($"Expected to exist ProductStatus ID 1 : {status.Description}");

		    // Example 2: Check if exists
        if (ProductStatus.Exists(2))
        {
            var found = ProductStatus.Get(2);
            Console.WriteLine($"\nFound product status (Get): {found.Description}");
        }

        // Example 3: Safe access with null check
        var maybeStatus = ProductStatus.GetOrDefault(99);
        if (maybeStatus == null) 
        { 
          Console.WriteLine("\nProduct status ID 99 does not exist");
        }

        // Example 4: Pattern matching for clean branching
        if (ProductStatus.TryGet(2, out var foundStatus))
        {
          Console.WriteLine($"\nFound Product status (TryGet): {foundStatus?.Description}");
        }
		
        Console.WriteLine("\nAll product statuses:");
        foreach (var s in ProductStatus.GetAll())
        {
            Console.WriteLine($"  - {s})");
        }
		
        OrderStatus.Initialize();
		    if (OrderStatus.Exists(1))
        {
            var orderStatus = OrderStatus.Get(1);
            Console.WriteLine($"\nFound order status: {status.Description}");
        }

        Console.WriteLine("\nAll order statuses:");
        foreach (var s in OrderStatus.GetAll())
        {
            Console.WriteLine($"  - {s.Id}-{s.Description}");
        }
    }
}

SmartEnum.cs

using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;

public abstract class SmartEnum<TValue, TSelf> 
    where TValue : class, ISmartEnumValue
    where TSelf : SmartEnum<TValue, TSelf>
{
    private static readonly Dictionary<int, TValue> _lookup = new();
    
    protected static TValue Register(TValue value)
    {
        _lookup[value.Id] = value;
        return value;
    }
    
    public static void Initialize()
    {
        RuntimeHelpers.RunClassConstructor(typeof(TSelf).TypeHandle);
    }
    
    public static TValue Get(int id)
    {
        if (_lookup.TryGetValue(id, out var value))
            return value;
        
        throw new KeyNotFoundException(
            $"Value with ID {id} not found in {typeof(TSelf).Name}");
    }
    
    public static TValue? GetOrDefault(int id) => _lookup.GetValueOrDefault(id);
    
    public static bool TryGet(int id, out TValue? value)
    {
        return _lookup.TryGetValue(id, out value);
    }
    
    public static bool Exists(int id) => _lookup.ContainsKey(id);
    public static IEnumerable<TValue> GetAll() => _lookup.Values;
}