You're building a collection that stores data in a custom tree structure. You want to iterate over all elements, but exposing the internal structure would break encapsulation. The Iterator pattern…
You're building a text editor with undo/redo functionality. Every action (typing, deleting, formatting) needs to be reversible. How do you track what happened and how to undo it? The Command…
You're building a system that loads large images. Loading all images at startup would be slow and memory-intensive. You need images to load only when accessed, with caching to avoid…
You're building a text editor that needs to render thousands of characters on screen. Each character could be an object with font, size, color, and style properties. Creating thousands of…
You're building an e-commerce checkout system. It needs to validate inventory, process payment, update stock, send confirmation emails, and create shipping labels. Your client code would need to know about…
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…