Design patterns are reusable solution to common problems that occur during software design and development. They provide a structured approach to solving design issues and promote code reusability, maintainability, and scalability.
Design patterns are not specific to a particular programming language or technology but are applicable to various software development contexts. They emerged as a result of capturing and formalizing best practices from experienced software designer and architects.
The concept of design patterns was popularized by the book “Design Patters: Elements of Reusable Object-Oriented Software” written by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides (also known as the Gang of Four or GoF). This book, published in 1994, introduced 23 design patterns classified into 3 categories: creational patterns, structural patterns, and behavioral patterns.
Here’s a brief overview of the three categories:
- Creational Patterns: These patterns focus on object creational mechanisms, providing flexibility in creating objects while hiding the complexity. Example include the Singleton pattern, Factory pattern, Abstract Factory pattern, and Builder pattern.
- Structural Patterns: These patterns deal with the composition of classes and objects to form larger structures while keeping them flexible and efficient. Examples include the Adapter pattern, Decorator pattern, Composite pattern and Proxy pattern.
- Behavioral Patterns: These patterns concentrate on communication between objects, defining how they interact and distribute responsibilities. Example include the Observer pattern, Strategy pattern, Command pattern, and Template Method pattern.