About this chapter
The rest of this course taught you what good design looks like - principles, SOLID, and the Gang of Four patterns. This final chapter is about the other direction: recognizing bad design and repairing it without breaking anything.
You'll start with a catalog of code smells, the small warning signs that something needs attention, each with a one-line tell and a pointer to the principle or pattern that fixes it. Then come the named anti-patterns - the big, well-known failure shapes like the God Object and the Big Ball of Mud - and why decent teams still drift into them.
After that you'll learn the refactoring techniques themselves: concrete, named moves you apply in small, safe steps, ideally behind tests. The chapter - and the course - ends with a capstone case study: one ugly PHP service refactored step by step, pulling together SRP, Strategy and dependency injection so you can see every idea working at once.
Lessons from courses
- 1 A catalog of common code smells A catalog of PHP code smells - long method, god class, duplicated code, feature envy, primitive obsession - each with a one-line tell and its fix.
- 2 Anti-patterns and why they happen The classic anti-patterns - God Object, Spaghetti Code, Golden Hammer, Big Ball of Mud, Copy-Paste Programming - why they emerge and what to do instead.
- 3 Core refactoring techniques Concrete PHP refactoring techniques - Extract Method, Extract Class, Rename, Parameter Object, Replace Conditional with Polymorphism - in small, safe steps.
- 4 A refactoring case study A full before-and-after: refactor one ugly PHP service with a fat, nested method into clean design using SRP, the Strategy pattern and dependency injection.