Design Patterns

Design patterns are reusable solutions to common problems that arise during software design. They provide general, proven approaches to design and help developers create software that is more modular, flexible, and maintainable.

Design Patterns

The term design pattern has roots in architecture and civil engineering. It was initially used to describe recurring solutions to design problems in these fields. The concept was later adapted and popularized in software engineering by the book Design Patterns: Elements of Reusable Object-Oriented Software, written by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. Those authors are commonly known as the Gang of Four (GoF). The book, published in 1994, introduced the concept of design patterns and formalized a set of recurring solutions to common problems in software design. The term has since become widely used in the software development community to describe these reusable and proven solutions.

Design patterns are typically divided into several categories based on their purpose and intent. The most common categorization includes creational, structural, and behavioral design patterns.

Creational Design Patterns

Creational design patterns focus on the process of object creation. These patterns provide solutions to instantiate objects or classes in a way that is flexible, and efficient, and promotes reusability. Creational patterns address various challenges such as ensuring a single instance of a class, defining an interface for creating objects without specifying their concrete classes, or creating families of related or dependent objects without specifying their classes. By offering guidelines, creational patterns contribute to the creation of modular, maintainable, and scalable software systems.

Design Patterns: Singleton
Singleton is a creational design pattern that ensures a class has only one instance while providing a global access point to this instance.
Design Patterns: Factory Method
The Factory Method design pattern is a creational pattern that addresses the challenge of creating objects without specifying their exact classes.
Design Patterns: Abstract Factory
The Abstract Factory design pattern serves as a solution to the challenge of creating families of related or dependent objects without coupling the client code to specific implementations.

Structural Design Patterns

Structural design patterns are concerned with the composition and organization of classes or objects to form larger, more complex structures. These patterns provide blueprints for creating relationships between entities, emphasizing the arrangement of components to achieve flexibility and maintainability in the overall system. Structural patterns include solutions such as adapting interfaces to work together seamlessly, dynamically attaching additional responsibilities to objects, or composing objects into tree structures to represent part-whole hierarchies. By addressing the organization and composition of elements, structural patterns contribute to the creation of software systems that are adaptable to change and exhibit a clear, modular structure.

Design Patterns: Adapter
The Adapter design pattern resolves interface incompatibility issues by acting as a bridge between classes with disparate interfaces. It allows the integration of existing classes without modifying their source code, facilitating collaboration between incompatible components.
Design Patterns: Decorator
The Decorator design pattern offers a versatile solution for dynamically extending the behavior of objects at runtime without altering their core structure.

Behavioral Design Patterns

Behavioral design patterns revolve around defining and managing the interactions and responsibilities among objects. These patterns focus on how objects collaborate, communicate, and distribute tasks within a system. Behavioral patterns provide solutions to design challenges related to communication between components, such as establishing one-to-many dependencies between objects, encapsulating algorithms and making them interchangeable, or encapsulating requests as objects, allowing for parameterization, queuing, and logging. By addressing the dynamic aspects of a system, behavioral patterns enhance the flexibility, extensibility, and maintainability of software, enabling developers to create applications that can gracefully adapt to changing requirements.

Design Pattern: Strategy
The Strategy design pattern allows the client to choose the appropriate algorithm at runtime, providing flexibility and promoting a clean separation of concerns.
Design Patterns: Observer
The Observer Pattern is a behavioral design pattern that facilitates the establishment of a one-to-many dependency between objects, where multiple observers are notified automatically of any state changes in a subject.