Implementing Domain-Driven Design

Lambda Syntax

If your language supports lambda expressions, it is possible to make otherwise repetitive code more compact by avoiding repetitive Event Stream management. To demonstrate this fact, here we introduce a helper method within our Application Service:

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public class CustomerApplicationService {   ...   public void Update(CustomerId id, Action<Customer> execute)   {     EventStream eventStream = _eventStore.LoadEventStream(id);     Customer customer = new Customer(eventStream.Events);     execute(customer);     _eventStore.AppendToStream(       id, eventStream.Version, customer.Changes);   }   ... }

In this method the parameter Action<Customer> execute references an anonymous function (C# delegate) that ...