Hi guys! I've been digging into ideas of Domain-Driven Design for a while and decided to share one cool pattern that I found in book: "Domain-Driven Design: Tackling Complexity in the Heart of Software" by Eric Evans (The Blue Book). If you haven't read this book yet - do that. Twice. Because it's so hard to get all concepts first time :) In this book Eric Evans describes Specification pattern which can make application more flexible. Today we're going to learn how to implement it.