You've built a text processing system. Now you need to add features: bold formatting, italic, encryption, compression. Do you create subclasses for every combination? BoldText, ItalicText, BoldItalicText, EncryptedBoldText... The Decorator…
You're building a file system explorer. Files are simple objects, but directories can contain both files and other directories. How do you write code that treats individual files and entire…
You're building an expense approval system. Expenses under £100 can be approved by a manager, under £1000 by a director, and above that by a VP. Hardcoding these rules creates…
You're building a drawing application that needs to support multiple shapes (circles, rectangles) and multiple rendering engines (vector, raster). Without careful design, you'll end up with a combinatorial explosion: CircleVector,…
You've just integrated a third-party payment library into your e-commerce application. Everything looks good until you realize the library expects PaymentRequest objects, but your codebase uses Order objects. Do you refactor your entire system,…
Clone Instead of Reconstruct
What if creating a new object is so expensive that copying an existing one is faster? What if you need to create objects without knowing their…