Hello, I'm Charmy

A practical guide to the Dependency Inversion Principle — why high-level modules should not depend on low-level implementations, and how abstractions and dependency injection fix the relationship.

A practical guide to the Interface Segregation Principle — what fat interfaces look like, why they cause problems, and how splitting them leads to cleaner, more flexible code.

A practical guide to the Liskov Substitution Principle — covering the classic Rectangle/Square problem, the Bird/Penguin example, and how to recognize LSP violations before they cause real trouble.

A practical guide to the Open/Closed Principle — what it actually means to be open for extension and closed for modification, with the classic shape area example and a real-world payment system.