Lift up Conditional - the magical refactoring

These are the slides from the two-hour List Up Conditional workshop at PulpoCon 2025 (September 19th 2025, Vigo, Spain).

The first time I saw this powerful refactoring technique demonstrated, I was confused. It seemed like some dark magic indeed. But then I tried a practical example for myself, got my head around it and fell in love. “Lift up conditional” allows you to take messy code filled with nested conditionals and repetitious code, and detangle it into something simple and beautiful that will suddenly be easier to understand and cheaper to maintain. Join me for a hands-on example and your own moment of revelation.

Transcript

1. Samman Learning Hour Lift up conditional License: CC-BY-SA-4.0 Attribution: sammancoaching.org @ClareSudbery
2. @ClareSudbery ALL LINKS FROM TODAY (including a link to these slides)
3. Which of the below if statements is equivalent to this one? if(colour1 == colour1 && colour2 == colour2) @ClareSudbery 1. if(true) 2. if(!(colour1 == "green" || colour2 == "blue")) 3. if(colour1 == "green" || colour2 == "blue") 4. if(colour1 != "green" || colour2 != "blue") 5. if(false)
4. Which of the below if statements is equivalent to this one? if(!(colour1 == "green" && colour2 == "blue")) @ClareSudbery 1. if(true) 2. if(!(colour1 == "green" || colour2 == "blue")) 3. if(colour1 == "green" || colour2 == "blue") 4. if(colour1 != "green" || colour2 != "blue") 5. if(false)
5. Which of the below if statements is equivalent to this one? if(colour1 != "green" && colour2 != "blue") @ClareSudbery 1. if(true) 2. if(!(colour1 == "green" || colour2 == "blue")) 3. if(colour1 == "green" || colour2 == "blue") 4. if(colour1 != "green" || colour2 != "blue") 5. if(false)
6. Which of the below if statements is equivalent to this one? if(colour1 == "green" && colour1 == "blue") @ClareSudbery 1. if(true) 2. if(!(colour1 == "green" || colour2 == "blue")) 3. if(colour1 == "green" || colour2 == "blue") 4. if(colour1 != "green" || colour2 != "blue") 5. if(false)
7. Which of the below if statements is equivalent to this one? if(!(colour1 != "green" && colour2 != "blue")) @ClareSudbery 1. if(true) 2. if(!(colour1 == "green" || colour2 == "blue")) 3. if(colour1 == "green" || colour2 == "blue") 4. if(colour1 != "green" || colour2 != "blue") 5. if(false)
8. @ClareSudbery Parsing if statements - solutions
9. Note to Clare: Go to PulpoCon Mural for schematics @ClareSudbery
10. Demo Lift up conditional Video @ClareSudbery Lift up conditional
11. @ClareSudbery • Code is here: https://github.com/emilybache/GildedRose-Refactoring-Kata • Requirements are in the readme • Visit this url to fork (top right), then clone the code: • https://github.com/emilybache/GildedRose-Refactoring-Kata.git • Choose your language Check you can run the tests in whichever language you are in. ! You probably want to delete “foo” tests. If you use csharp.xUnit, delete the two “foo” tests in ApprovalTest.cs and GildedRoseTest.cs Lift up conditional
12. @ClareSudbery • Code is here: https://github.com/emilybache/GildedRose-Refactoring-Kata • Requirements are in the readme • Visit this url to fork (top right), then clone the code: • https://github.com/emilybache/GildedRose-Refactoring-Kata.git • Choose your language Use the demonstrated method to “lift up” the conditional. ! If you use csharp.xUnit, delete the two “foo” tests in ApprovalTest.cs and GildedRoseTest.cs Lift up conditional
13. Mid-exercise check-in @ClareSudbery Lift up conditional
14. @ClareSudbery • Code is here: https://github.com/emilybache/GildedRose-Refactoring-Kata • Requirements are in the readme • Visit this url to fork (top right), then clone the code: • https://github.com/emilybache/GildedRose-Refactoring-Kata.git • Choose your language Use the demonstrated method to “lift up” the conditional. ! If you use csharp.xUnit, delete the two “foo” tests in ApprovalTest.cs and GildedRoseTest.cs Lift up conditional
15. How confident do you feel about your ability to use the "lift up conditional" technique? @ClareSudbery 1. Not at all 2. A little 3. Medium 4. Confident 5. Very confident
16. How confident do you feel that this is an effective technique? @ClareSudbery 1. Not at all 2. A little 3. Medium 4. Confident 5. Very confident
17. Questions? @ClareSudbery Lift up conditional
18. @ClareSudbery Trifork Academy, Amsterdam Mon Nov 17 + Tue Nov 18, 2025 Two-day workshop “Building Robust Maintainable Software Using genAI”
20. Sudbery Software Engineering Ltd Does your team want help to improve their software delivery? Coaching, keynotes & workshops Events and info: bit.ly/claresudbery Mastodon: mastodon.social/@ClareSudbery LinkedIn: bit.ly/lin-csudbery Podcast: bit.ly/3XvyNbU
21. @ClareSudbery ALL LINKS FROM TODAY (including a link to these slides)
22. See you next time!