Design Patterns

Design patterns are proven solutions to common problems in software development. They are not rigid rules, but guidelines.

Classification

1. Creational Patterns: Focus on how objects are created (for example, Singleton, Factory).
2. Structural Patterns: How objects are organized and composed (for example, Adapter, Composite).
3. Behavioral Patterns: How objects interact and communicate.

State Pattern

Allows an object to change its behavior when its internal state changes. Ideal for avoiding many complex if/else blocks.

Example: A music player with Playing, Paused, and Stopped states.

Template Method Pattern

Defines the structure of an algorithm in a superclass, but allows subclasses to override specific steps without changing the overall structure.

Example: A board game where all games have the steps start(), play(), and finish(), but each game implements them differently.