Fluent method chaining in C# and code so clear your users can read it!

LeedsSharp are proud to present Andrew Poole in "Fluent method chaining in C# and orchestration code so clear your product owner can read it!"

Please note this event is a week earlier than its usual date.

Abstract:

What if there was a way to declaratively describe a chain or flow of methods, especially async methods, which could be used when handling API requests or messages from a queue or anywhere actually? What if that flow of methods was self-documenting and understandable at a glance?

Recently, while refactoring a growing piece of business logic, my team and I found a way to achieve this. My talk tells the story of that refactoring journey. It is a mixture of slides and live coding demos in Visual Studio, where I show that the flows of chained methods are easy to read, navigate, debug and test. We end up with orchestration code which describes a whole system or vertical slice and, with some care, is even readable by product owners and business analysts!
I start by describing the problem and some background, including the use of discriminated unions in C# (using OneOf) and I set out the aims we had for the refactoring effort.
Next, I demonstrate the solution we came up with and how easy it is to use. Then I do a deep dive into the extension methods which enable the method chaining.
Next, I introduce the concept of orchestration by co-locating related flows together in a single class.
I go back to the demo, show some orchestration code, and add more chained methods, showing a few more features.
I complete the demo by introducing an end-to-end component test and stepping through it in the debugger, while it tests the entire orchestration flow.
I discuss that while our solution is event sourced, it is flow driven. Then I finish with some limitations and conclusions.