Architecture

TL;DR - Default Interface Methods vs Abstract Methods Use default interface methods for API evolution and optional behavior without breaking existing code. Use abstract methods and classes for shared state, dependency injection, and complex inheritance. Interfaces support multiple inheritance; abstract classes do not. Abstract classes allow fields, constructors, and access modifiers; interfaces do not. Performance is similar; choose based on design and maintainability. Default interface methods arrived in C# 8, letting you add implementation directly to interfaces. But when should you use them over traditional abstract methods? ...

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. ...