adamfur/AtomicGraph

AtomicGraph

public class Shop
{
	public int Orders { get; set; }
	public decimal TotalSum { get; set; }
	
	public void Checkout(Basket basket)
	{
		++Orders
		TotalSum += basket.Sum();
	}
}

Scenario 1

A proper Basket item is submitted to Checkout

Orders is increased by one, and TotalSum is increased by the Sum of the order

Consistency is preserved

Scenarion 2

A null object is submitted to Checkout

Order is increased by one, and code throws NullRferenceEXception.

Shop is now corrupt

Instead!

public class Shop
{
	public Atomic<int> Orders { get; set; } = new Atomic<int>();
	public Atomic<decimal> TotalSum { get; set; } = new Atomic<decimal>();
	
	public void Checkout(Basket basket)
	{
		++Orders
		TotalSum += basket.Sum();
	}
}