Last week we worked out how to parse our new items form, albeit with NullPointer exceptions to handle missing or invalid data.
The feedback I got from David Denton, one of the http4k developers, was “You know you can use the form lenses here and avoid all this bullshit?”
So this episode we’ll refactor the current code to use form lenses, and see how much bullshit we actually avoid.
Significant moments
* 00:00:38 We found two bugs
* 00:01:35 Recreate a bug in the tests
* 00:04:00 Fix the bug as quickly as possible
* 00:04:47 Refactor to make things better
* 00:05:36 Add some test for other things that might not work
* 00:06:15 They do work, so commit
* 00:06:27 Review our implementation and our tests
* 00:07:26 Refactor our tests to reveal intention
* 00:09:40 Refactor parsing to use lenses
* 00:13:21 AI Assistant comes in handy
* 00:15:17 IntelliJ refactoring bug
* 00:21:23 http4k bug
* 00:23:49 Use lenses to diagnose multiple failures
* 00:24:37 Inline and extract to refactor to better semantics
* 00:30:17 Raise an event for parse failures
* 00:31:22 Callback to Errors are Events episode
* 00:31:25 Creating a custom Hamkrest matcher
* 00:38:02 Commit
* 00:38:14 Review
* 00:38:46 Fix bug where we have two intertwingled forms
* 00:41:19 Review
This is part 86 of an exploration of where a Test Driven Development implementation of the Gilded Rose stock control system might take us in Kotlin. You can see the whole series as a playlist
and the code on GitHub
If you like this, you’ll probably like my book Java to Kotlin, A Refactoring Guidebook
(
http://java-to-kotlin.dev). It's about far more than just the syntax differences between the languages - it shows how to upgrade your thinking to a more functional style.