5 Underused C# Features That Make Defensive Code Obsolete

5 Underused C# Features That Make Defensive Code Obsolete Modern C# Is Better at Protecting Your Invariants Than You Are Cristian Sifuentes · 2026 · #dotnet #csharp #architecture #performance Defensive programming used to be a badge of seniority. Null checks everywhere. Guard clauses in every method. Private setters “just in case.” Constructors bloated with validation logic. Unit tests verifying invariants that the type system should have enforced in the first place. But modern C# (10–13) quietly changed the deal. The language and runtime now offer mechanisms that encode intent directly into the type system and flow analysis , reducing entire categories of runtime defensive code to compile-time guarantees. This article is not about syntactic sugar. It’s about removing whole layers of defensive friction using five features that most teams still underuse. Every example below is production-oriented. Every insight is rooted in the code. 1. required Members — Compile-Time Invariants For yea