C# Online Compiler | .NET Fiddle

using System;
using System.Linq;
using System.Collections.Generic;
					
public class Program
{		
	public static void Main()
	{
		var productService = new ProductService();
        productService.GetProducts();

        Console.WriteLine("------");

        var cacheProductService = new CacheProductService(new ProductService());
        cacheProductService.GetProducts();

        Console.WriteLine("------");

        var logProductService = new LogProductService(new CacheProductService(new ProductService()));
        logProductService.GetProducts();
	}
}

public record Product;
	
public interface IProductService
{
	List<Product> GetProducts();
}

public class ProductService : IProductService
{
    public List<Product> GetProducts()
    {
        Console.WriteLine("Products fetched");

        return Enumerable.Empty<Product>().ToList();
    }
}

public abstract class ProductServiceDecorator : IProductService
{
    protected IProductService ProductService { get; }

    protected ProductServiceDecorator(IProductService productService)
    {
        ProductService = productService;
    }

    public abstract List<Product> GetProducts();
}

public class CacheProductService : ProductServiceDecorator
{
    public CacheProductService(IProductService productService) : base(productService)
    {
    }

    public override List<Product> GetProducts()
    {
        Console.WriteLine("Products cached");

        return ProductService.GetProducts();
    }
}

public class LogProductService : ProductServiceDecorator
{
    public LogProductService(IProductService productService) : base(productService)
    {
    }

    public override List<Product> GetProducts()
    {
        Console.WriteLine("Request logged");

        return ProductService.GetProducts();
    }
}

 
using System;
using System.Linq;
using System.Collections.Generic;
                    
public class Program
{       
    public static void Main()
    {
        var productService = new ProductService();
        productService.GetProducts();
​
        Console.WriteLine("------");
​
        var cacheProductService = new CacheProductService(new ProductService());
        cacheProductService.GetProducts();
​
        Console.WriteLine("------");
​
        var logProductService = new LogProductService(new CacheProductService(new ProductService()));
        logProductService.GetProducts();
    }
}
​
public record Product;