SOLID Principles

Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation and Dependency Inversion in modern C#.

1. What does the Single Responsibility Principle really mean, and how do you apply it in a .NET codebase without creating hundreds of tiny classes?

   SRP as one reason to change (one actor), spotting violations, splitting by change drivers, and avoiding over-fragmentation.

   Mid-Level Architecture SOLID Principles · 🔗 3 follow-ups · 🛠 1 real-world
2. What is the Open/Closed Principle, and how do you apply it in C# without building speculative plug-in frameworks?

   Open for extension, closed for modification; strategy, polymorphism, DI and pattern-based extension; when a switch is fine; avoiding speculative generality.

   Mid-Level Architecture SOLID Principles · 🔗 3 follow-ups · 🛠 1 real-world
3. Explain the Liskov Substitution Principle with a C# example of a violation, and how you would detect and fix it.

   Behavioural subtyping, preconditions, postconditions and invariants, NotSupportedException smells, the read-only collection example, and fixing hierarchies.

   Senior Architecture SOLID Principles · 🔗 3 follow-ups · 🛠 1 real-world
4. What is the Interface Segregation Principle, and how do you apply it to repositories, services and libraries in .NET?

   Client-specific interfaces, fat interface smells, read and write splits, role interfaces, default interface methods and avoiding interface explosion.

   Mid-Level Architecture SOLID Principles · 🔗 3 follow-ups · 🛠 1 real-world
5. What is the Dependency Inversion Principle, how is it different from dependency injection, and how do you apply it in a layered .NET application?

   High-level policy not depending on low-level details, abstraction ownership, DIP versus DI versus IoC containers, ports and adapters, and when not to invert.

   Senior Architecture SOLID Principles · 🔗 3 follow-ups · 🛠 1 real-world