Design Patterns

Design patterns are recurring solutions to common problems encountered during software development. They represent best practices for designing and structuring code to achieve specific objectives while promoting maintainability, scalability, and flexibility.

Here are some commonly recognized design patterns:

1. Creational Patterns:
   • Singleton: Ensures a class has only one instance and provides a global point of access to it.
   • Factory Method: Defines an interface for creating an object, but lets subclasses alter the type of objects that will be created.
   • Abstract Factory: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
2. Structural Patterns:
   • Adapter: Allows incompatible interfaces to work together by wrapping an interface around an existing class.
   • Decorator: Attaches additional responsibilities to an object dynamically, providing a flexible alternative to subclassing for extending functionality.
   • Facade: Provides a unified interface to a set of interfaces in a subsystem, simplifying their usage.
3. Behavioral Patterns:
   • Observer: Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
   • Strategy: Defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
   • Command: Encapsulates a request as an object, thereby allowing for parameterization of clients with queues, requests, and operations.
4. Architectural Patterns:
   • Model-View-Controller (MVC): Separates the representation of information from the user’s interaction with it, allowing independent development, testing, and maintenance of each component.
   • Layered Architecture: Divides the software into distinct layers where each layer performs a specific set of tasks, promoting maintainability and scalability.
   • Microservices: Architectural style that structures an application as a collection of loosely coupled services, each encapsulating a specific business capability.
5. Concurrency Patterns:
   • Producer-Consumer: Involves two processes, a producer that produces data, and a consumer that consumes that data concurrently, avoiding issues like race conditions.
   • Thread Pool: Manages a group of threads, improving performance by reducing the overhead associated with creating and destroying threads for short-lived tasks.
6. Anti-patterns:
   • Singletonitis: Overuse of the singleton pattern, leading to tight coupling and reduced flexibility.
   • Spaghetti Code: Unstructured and tangled code that is difficult to understand and maintain.
   • God Object: A single class that handles all or most of the application’s functionality, violating principles of modularity and separation of concerns.

Understanding these patterns and knowing when to apply them appropriately can significantly improve the quality and maintainability of software systems. However, it’s crucial to use them judiciously and adapt them to the specific requirements and constraints of each project.