Domain-Driven Design in PHP

In-Memory Implementation

As Uncle Bob wrote in Screaming Architecture:

A good software architecture allows decisions about frameworks, databases, web-servers, and other environmental issues and tools, to be deferred and delayed. A good architecture makes it unnecessary to decide on Rails, or Spring, or Hibernate, or Tomcat or MySql, until much later in the project. A good architecture makes it easy to change your mind about those decisions too. A good architecture emphasizes the use-cases and decouples them from peripheral concerns.

In the early stages of your application, a fast in-memory implementation could come in handy. It's something you could use to mature other parts of your system, allowing you to delay database decisions to the ...