Practical tips for keeping your C# code base clean

As soon as a codebase grows to a certain point, almost every team struggles to keep that codebase under control. Coding conventions are no longer followed, code reviews become superficial, refactoring doesn't happen as often as it should, and developers lose sight of the original architecture. Fortunately our toolbox contains quite some tools to help you with this, and next to that there are plenty of practices and learnings to help structure your code in more functional manner.

1. 40 practical tips for keeping your C# code base healthy Dennis Doomen @ddoomen | Principal Consultant | Microsoft MVP

2. About Me Coding Architect .NET/C# Bit of TS/JS/React/Vue 29 years of “pro” experience Author of FluentAssertions , Pathy, PackageGuard , Reflectify , .NET Library Starter Kit www.dennisdoomen.com BlueSky, Twitter, Mastodon, LinkedIn

3. Establish clean source control guidelines

4. Establish (HTTP) exception and logging guidelines

5. Merge microservices that don't need independent scaling µService µService µService µService µService µService µService µService µService µService µService µService µService µService µService µService Modular Monolith µService µService µService µService Service Service Service Service Service Service

6. Align projects with the deployment or reusability scope

7. Make the folder structure explain the architecture

8. Keep concrete classes internal by only exposing an interface

9. Use . editorconfig and Prettier to automatically format code

10. Use .NET analyzers and ESLint to get early code quality feedback

11. Use JetBrain’s Cleanup Profiles for auto clean-up

12. Use directory.build.props and . editorconfigs to gradually enforce standards

13. Document the purpose of code, not how it does that

14. Organize code by functionality

15. Clarify code review comment intent https://github.com/erikthedeveloper/code-review-emoji-guide

16. Consider Central Package Management Directory.packages.props MyProject.csproj y

17. Name and group tests functionally

18. Use a well-known branching strategy

19. Split refactoring commits from the rest

20. Use fixup commits and interactive rebases

21. Reduce dependencies on unstable packages Main Package Application More stable package Contract Contract Source-only package Auxiliary Package Optional Dependency Dependency Package

22. Refactor using the Rule of Three

23. Keep code internal

24. Use PolySharp to use newer C# features

25. Shared Module Module 1 Deduplicate complicated reusable code Complicated logic Module 2 Complicated logic Module 3 Complicated logic Module 1 Complicated logic Module 2 Module 3 Shared Module

26. Duplicate and simplify Shared Module Module 1 Simplified logic Module 2 Simplified logic Module 3 Simplified logic Module 1 Overly generic code Module 2 Module 3 Shared Module

27. Split shared projects to reduce dependencies Shared Project Project 1 Project 2 Project 3 Project 1 Project 2 Project 3 Shared Project Shared Project Shared Project

28. Replace lots of dependencies with a single reversed interface MyController ISomeRepository IExternalService IOtherModule Specific interface Adapter ISomeRepository IExternalService IOtherModule MyController

29. Get rid of separate validators and query/handlers patterns Finance Controller Some Request Handler Request validator IValidate < RequestValidator > IHandle < SomeRequestQuery >

30. Don’t forget the OO principles

31. Replace List<T> or Dictionary<T> with a custom collection class Order OrderLine List< OrderLine > Order OrderLine OrderLineCollection

32. Don't introduce interfaces if you don't need them

33. Move container registrations into the functional folder

34. Split bloated interfaces Finance Service IFinanceService Finance Service IProvideVatRates ICalculateIncomeTaxes ITransactionHistory

35. Replace single-method interfaces with delegates

36. Ensure every PR makes the code a little bit better

37. Use // REFACTOR and // SMELL comments https://www.infoq.com/articles/natural-course-refactoring/

38. Keep your licenses in check

39. Learn to use AI assistants and agents

40. Spell check your code

41. Replace Bicep & Terraform with Pulumi

42. Switch to GitHub and Dependabot or adopt Renovate

43. Use Nuke to evolve your build script over time

44. Learn from others

45. Find me at bluesky : @ddoomen.bsky.social mastodon : @ddoomen.mastodon.social twitter : ddoomen email : [email protected]