Behavioral Patterns
How objects talk to each other and share responsibilities.
10 lessons · follow them in order, or jump to what you need.
Chain of Responsibility Pattern: Pass the Request Until Someone Handles It
Learn the Chain of Responsibility pattern with a simple school leave application story, easy TypeScript and C# code, diagrams, tables, and practice tasks.
Command Pattern: Turn Every Action into an Order Slip
Learn the Command pattern through a restaurant order slip story. Simple TypeScript and C# code with undo and redo, diagrams, tables, and practice tasks.
Iterator Pattern: Visit Every Element, One Seat at a Time
Learn the Iterator pattern with a railway ticket checker story. Build a custom iterator in TypeScript, use for...of and generators, plus C# IEnumerable.
Mediator Pattern: The Control Tower That Stops the Chaos
Learn the Mediator pattern with an airport control tower story, simple TypeScript and C# code, MediatR examples, diagrams, tables and easy practice tasks.
Memento Pattern: Save Your Game Before the Boss Fight
Understand the Memento pattern through a video game save point story, with TypeScript and Python undo examples, diagrams, tables and easy practice tasks.
Observer Pattern: Press Subscribe and Ring the Bell
Master the Observer pattern with a YouTube subscribe and bell icon story, TypeScript and C# event code, real software uses, diagrams and practice tasks.
State Pattern: The Fan That Changes Its Mood
Learn the State design pattern with a ceiling fan regulator story, simple TypeScript and C# code, state diagrams, real software examples, and practice.
Strategy Pattern: Cycle, Bus, or Auto — You Choose
Learn the Strategy design pattern with a simple school travel story, easy TypeScript and C# code, runtime swapping, real examples, and practice tasks.
Template Method Pattern: Chai and Coffee, Same Steps
Learn the Template Method design pattern with a chai and coffee story, easy TypeScript and C# code, hooks, diagrams, real examples, and practice tasks.
Visitor Pattern: The Doctor Who Visits Every Class
Learn the Visitor design pattern with a school health check-up story, double dispatch made simple, TypeScript and C# code, real examples, and practice.