Discover how C# extension methods let you inject behavior into types you can’t change. Learn when to use them, see practical examples, and follow best practices for clean, maintainable code without inheritance or wrappers.
TL;DR - abstract vs interface Abstract class: Shared implementation + state management, supports constructors for initialization Interface: Pure contracts + multiple inheritance, no constructors Use abstract classes when you need shared logic, protected members, or default behavior that can be overridden Use interfaces when you need flexible contracts, multiple inheritance, or mocking capabilities 1. When should you choose an abstract class over an interface in C#? Choose abstract classes when you need shared implementation logic and state management across derived types. Interfaces work for contracts, but abstract classes handle common behavior. ...
Discover how composition helps you follow the SOLID principles in C#. See practical examples for each principle, learn why composition is more flexible than inheritance, and get actionable tips for writing robust, testable, and maintainable code.
Discover why composition is often a better choice than inheritance in C#. This article explains the drawbacks of deep inheritance, demonstrates how to use composition for flexible and maintainable code, and provides practical tips for applying these principles in real-world projects. Includes code examples and guidance for testable, scalable software design.
Discover how to use encapsulation and information hiding to write safer, more maintainable C# code. This article covers practical examples, common pitfalls, and modern C# features for protecting internal state and exposing clear, stable interfaces.
Discover how polymorphism makes C# code more flexible and future-proof. See how to replace switch statements with interfaces, add new features without breaking existing code, and write modular, testable business logic. Includes practical examples and actionable best practices for modern C# development.
Learn the key differences between method overloading and overriding in C#. See clear code examples, a quick comparison table, and practical interview tips. Master these essential OOP concepts to write flexible, maintainable, and testable C# code.
Discover why private fields are crucial for safe, maintainable C# code. See the dangers of public fields, how private fields enable validation and business logic, and get actionable tips for robust object design with real-world examples.
TL;DR: Abstract Class in C# - TL;DR What Is Abstract Class? Definition: Incomplete class that cannot be instantiated directly Purpose: Blueprint for related classes with shared behavior Keywords: abstract class, abstract methods, override in derived classes Key Features Mixed Implementation: Can have both concrete methods and abstract methods State: Can contain fields, properties, constructors Access Modifiers: Supports private, protected, internal members Inheritance: Single inheritance only Abstract vs Virtual Methods Abstract: No implementation, must be overridden Virtual: Has default implementation, can be overridden Regular: Concrete implementation, cannot be overridden When to Use Abstract Classes Share code between related classes Need constructors or protected members Template method pattern (define workflow, customize steps) Enforce implementation while providing base functionality Limitations of Abstract Classes Cannot be instantiated directly Single inheritance only Cannot be sealed Common Use Cases Framework/SDK base classes Database providers Document processors Any scenario needing shared behavior + enforced implementation Picture this: you’re building a document management system where users can create Word documents, PDFs, and Excel files. Each document type has its own specific formatting and processing logic, but they all share common behaviors, they need to be saved, validated, and have metadata tracked. ...
TL;DR: Interface in C# - TL;DR What Is It Definition: Pure contract defining what methods/properties a class must have Purpose: Define capabilities without implementation details Keywords: interface, class : IInterface, implement multiple Key Features No Implementation: Methods are abstract by default (C# 8+ allows default implementations) No State: Cannot have instance fields or constructors Access: All members implicitly public Inheritance: Classes can implement multiple interfaces Interface Types Method Signatures: Define what methods must exist Properties: Define required properties (get/set) Events: Define event contracts Default Methods: C# 8+ allows method implementations in interfaces When to Use Multiple contracts needed on same class Dependency injection and testing (easy mocking) Plugin/modular architecture Define capabilities across unrelated classes “Can-do” relationships (ISerializable, IComparable) Benefits Flexibility: Multiple implementation support Testability: Easy to mock for unit tests Loose Coupling: Depend on contracts, not concrete classes Polymorphism: Treat different classes uniformly Common Patterns Repository pattern (IRepository<T>) Service contracts (IEmailService, IPaymentService) Strategy pattern (different algorithms, same interface) Dependency injection containers Limitations No shared implementation (mostly) All members must be public Cannot contain instance state You’re building an e-commerce platform and need to send notifications, order confirmations, shipping updates, promotional emails. Right now you’re using an email service, but next month the marketing team wants SMS notifications too. Later, they might want push notifications or Slack alerts. ...