Decorator Pattern: How to Add Features to Objects Without Subclass Sprawl

The Decorator is a structural design pattern from the Gang of Four (GoF) catalog that lets developers add behavior to individual objects dynamically without modifying their source code or creating excessive subclasses. It works by wrapping the original object in additional layers that each contribute a single, focused responsibility, keeping code clean and modular. A DEV Community article explains the pattern using a Java example involving graphical components like buttons, borders, and shadows. The abstract decorator holds a reference to a base Component interface and calls the original behavior before appending new functionality, enabling runtime composition of behaviors. The pattern is recommended when inheritance feels too rigid and when multiple behavior combinations would otherwise require an unmanageable number of subclasses.