SOLID Refactoring

This repository provides examples of code refactoring to implement SOLID principles:

• Single Responsibility principle (SRP)
• Open/closed principle (OCP)
• Liskov Substitution principle (LSP)
• Interface Segregation principle (ISP)
• Dependency injection principle (DIP)

You can find 2 commits:

• #1 - first, "bad" version of code
• #2 - refactored, "good" version of code

Of course, there could be done deeper refactoring, but I decide to show some simple steps to implement this:

• Move code that solves not direct problem to different class, it solves SRP (e.g. OrderRepository, AnalyticsService, NotificationService, ReportService)
• Combine same code to a class, it will be easier to change similar logic after if you need, it solves OCP (e.g. Logger, ConsoleLogger, OrderRepository)
• Add small interfaces, it solves ISP (e.g. Logger)
• Instead of if statements use inheritance and provide abstract methods to child, it solves LSP (e.g. Order, DigitalOrder, PhysicalOrder)
• Inject dependencies, do not create objects by yourself, it solves DIP (e.g. OrderManager)
• Move object's logic to object itself, it solves SRP (e.g. Order)