What are Design Patterns? - Explanation & Meaning

Definition

Design patterns are proven, reusable solutions to commonly occurring problems in software design. They are not ready-made code but conceptual templates that developers can apply to specific situations in their own architecture.

Technical explanation

The Gang of Four (GoF) catalogued 23 design patterns in three categories: creational, structural, and behavioral patterns. Creational patterns like Singleton (one instance), Factory Method (delegate object creation), and Builder (construct complex objects step by step) control how objects are created. Structural patterns like Adapter (connect incompatible interfaces), Decorator (dynamically add functionality), and Facade (simplified interface) define how objects are composed. Behavioral patterns like Observer (event-based communication), Strategy (interchangeable algorithms), and Command (requests as objects) describe how objects communicate. In modern TypeScript/JavaScript development, some patterns are built into the language: modules replace Singleton, higher-order functions replace Strategy, and event emitters implement Observer. Patterns like Repository, Unit of Work, and CQRS (Command Query Responsibility Segregation) are popular in contemporary application architecture. Knowing design patterns improves communication between developers through a shared vocabulary.

How MG Software applies this

At MG Software, we consciously apply design patterns where they add value. We use the Repository pattern for data abstraction, Observer/Event patterns for real-time functionality, Factory patterns for creating configurable services, and Strategy patterns for interchangeable business rules. We choose patterns based on the specific problem, not to apply patterns for the sake of patterns.

Practical examples

• An e-commerce platform using the Strategy pattern to handle different payment methods (iDEAL, credit card, PayPal) through a uniform interface, making it easy to add new payment methods.
• A notification system implementing the Observer pattern so multiple channels (email, push, SMS) are automatically informed when an event occurs.
• A reporting system using the Builder pattern to construct complex reports step by step with optional sections, filters, and visualizations.

Related terms