A Brewer's Guide to Filtering out Complexity and Churn (RubyConf Mini 2022 Edition)

RubyConf Mini 2022 presentation by Alan Ridlehoover & Fito von Zastrow

Mechanical coffee machines are amazing! You drop in a coin, listen for the clink, make a selection, and the machine springs to life, hissing, clicking, and whirring. Then the complex mechanical ballet ends, splashing that glorious, aromatic liquid into the cup. Ah! C’est magnifique!

There’s just one problem. Our customers also want soup! And, our machine is not extensible. So, we have a choice: we can add to the complexity of our machine by jamming in a new dispenser with each new request; or, we can pause to make our machine more extensible before development slows to a halt.

Here's the video of the talk: https://youtu.be/RJRSosxtzbU

Transcript

1. Alan Ridlehoover & Fito von Zastrow RubyConf Mini 2022 The Coffee Machine Talk A Brewer’s Guide to Filtering out Complexity and Churn
2. PRONOUNS he/him/his HOMETOWN Asunción
 RUBY EXPERIENCE 12 years FAVORITE COFFEE Ghirardelli Dark Chocolate Mocha PRONOUNS he/him/his HOMETOWN Seattle
 RUBY EXPERIENCE 12 years FAVORITE COFFEE New Orleans Cold Brew w/ Chicory
4. 🤲
7. 👍
8. How did we get here? How complexity sneaks into a code base.
9. ☕ Story: As a patron, I want coffee class CoffeeMachine def vend dispense_cup heat_water prepare_grounds dispense_water dispose_of_grounds end end
10. ☕ Story: As a patron, I want tea class CoffeeMachine def vend(drink: :coffee) if drink == :coffee dispense_cup heat_water prepare_grounds dispense_water dispose_of_grounds elsif drink == :tea dispense_cup dispense_tea_bag heat_water dispense_water end end end
11. ☕ Refactor: DRY up the code class CoffeeMachine def vend(drink: :coffee) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispose_of_grounds if drink == :coffee end end
12. ☕ Story: As a patron, I want sweetener class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispense_sweetener if options[:sweet] dispose_of_grounds if drink == :coffee end end
13. ☕ Story: As a patron, I want cream class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispense_sweetener if options[:sweet] dispense_cream if options[:creamy] dispose_of_grounds if drink == :coffee end end
14. ☕ Story: As a patron, I want cocoa class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end dispose_of_grounds if drink == :coffee end end
15. ☕ Story: As a patron, I want whipped cream class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end unless drink == :tea dispense_whipped_cream if options[:fluffy] end dispose_of_grounds if drink == :coffee end end
16. Do you smell that? How to recognize the problem before it becomes painful and frustrating. Rules by Sandi Metz Flog by Ryan Davis
17. ☕ Measuring complexity with the flog gem Score of Means - - - - - - - - - - - - - - - - - - - - - - - - - 0-10 Awesome 11-20 Good enough 21-40 Might need refactoring 41-60 Possible to justify 61-100 Danger 100-200 Whoop, whoop, whoop 200 + Someone please think of the children (note: these are scores for an individual method) What's a good fl og score? by Jake Scruggs
18. ☕ Story: As a patron, I want coffee class CoffeeMachine def vend dispense_cup heat_water prepare_grounds dispense_water dispose_of_grounds end end Churn 1 Complexity 5.5 10 20 30 25 15 5 0
19. ☕ Story: As a patron, I want tea class CoffeeMachine def vend(drink: :coffee) if drink == :coffee dispense_cup heat_water prepare_grounds dispense_water dispose_of_grounds elsif drink == :tea dispense_cup dispense_tea_bag heat_water dispense_water end end end Churn 2 Complexity 14.6 10 20 30 25 15 5 0
20. ☕ Refactor: DRY up the code class CoffeeMachine def vend(drink: :coffee) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispose_of_grounds if drink == :coffee end end Churn 3 Complexity 10.9 10 20 30 25 15 5 0
21. ☕ Story: As a patron, I want sweetener class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispense_sweetener if options[:sweet] dispose_of_grounds if drink == :coffee end end Churn 4 Complexity 13.5 10 20 30 25 15 5 0
22. ☕ Story: As a patron, I want cream class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag end dispense_water dispense_sweetener if options[:sweet] dispense_cream if options[:creamy] dispose_of_grounds if drink == :coffee end end Churn 5 Complexity 16.0 10 20 30 25 15 5 0
23. ☕ Story: As a patron, I want cocoa class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end dispose_of_grounds if drink == :coffee end end Churn 6 Complexity 21.3 10 20 30 25 15 5 0
24. ☕ Story: As a patron, I want whipped cream class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end unless drink == :tea dispense_whipped_cream if options[:fluffy] end dispose_of_grounds if drink == :coffee end end Churn 7 Complexity 25.5 10 20 30 25 15 5 0
25. ☕ CoffeeMachine Pain Index over time class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end unless drink == :tea dispense_whipped_cream if options[:fluffy] end dispose_of_grounds if drink == :coffee end end Churn 7 Complexity 25.5 10 20 30 25 15 5 0
26. ☕ CoffeeMachine Pain Index over time class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end unless drink == :tea dispense_whipped_cream if options[:fluffy] end dispose_of_grounds if drink == :coffee end end Churn 7 Complexity 25.5 10 20 30 25 15 5 0
27. Can we turn it around? How to fi lter out complexity and churn.
28. ☕ Refactor: Rehydrate to see missing abstractions class CoffeeMachine def vend(drink: :coffee, options: {}) dispense_cup heat_water if drink == :coffee prepare_grounds elsif drink == :tea dispense_tea_bag elsif drink == :cocoa dispense_cocoa_mix end dispense_water unless drink == :cocoa dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end unless drink == :tea dispense_whipped_cream if options[:fluffy] end dispose_of_grounds if drink == :coffee end end
29. ☕ Refactor: Rehydrate to see missing abstractions class CoffeeMachine def vend(drink: :coffee, options: {}) if drink == :coffee dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds elsif drink == :tea dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] elsif drink == :cocoa dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end end
30. ☕ Refactor: Extract polymorphic objects class CoffeeMachine def vend(drink: :coffee, options: {}) if drink == :coffee Coffee.new(options: options).prepare elsif drink == :tea Tea.new(options: options).prepare elsif drink == :cocoa Cocoa.new(options: options).prepare end end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
31. ☕ Refactor: Extract polymorphic objects class CoffeeMachine def vend(drink: :coffee, options: {}) if drink == :coffee Coffee.new(options: options).prepare elsif drink == :tea Tea.new(options: options).prepare elsif drink == :cocoa Cocoa.new(options: options).prepare end end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
32. ☕ Refactor: Extract factory class class CoffeeMachine def vend(drink: :coffee, options: {}) BeverageFactory.build(drink, options).prepare end end class BeverageFactory def self.build(drink, options) if drink == :coffee Coffee.new(options: options) elsif drink == :tea Tea.new(options: options) elsif drink == :cocoa Cocoa.new(options: options) end end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
33. ☕ Refactor: Extract factory class class CoffeeMachine def vend(drink: :coffee, options: {}) BeverageFactory.build(drink, options).prepare end end class BeverageFactory def self.build(drink, options) if drink == :coffee Coffee.new(options: options) elsif drink == :tea Tea.new(options: options) elsif drink == :cocoa Cocoa.new(options: options) else NullBeverage.new(options: options) end end end class NullBeverage def prepare # no-op end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
34. ☕ Refactor: Use convention to prevent churn class CoffeeMachine def vend(drink: :coffee, options: {}) BeverageFactory.build(drink, options).prepare end end class BeverageFactory def self.build(drink, options) klass = drink.capitalize if Module.const_defined?(klass) Module.const_get(klass).new(options: options) else NullBeverage.new(options: options) end end end class NullBeverage def prepare # no-op end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
35. ☕ Complexity of the CoffeeMachine class over time Rehydrate Extract Classes Introduce Factory Whipped Cream Cocoa Cream Sweetener DRY Tea Co ff ee 10 20 30 25 15 5 0 40 35
36. ☕ Complexity of the CoffeeMachine class over time Rehydrate Extract Classes Introduce Factory Whipped Cream Cocoa Cream Sweetener DRY Tea Co ff ee 10 20 30 25 15 5 0 40 35
37. ☕ Complexity of the CoffeeMachine class over time Rehydrate Extract Classes Introduce Factory Whipped Cream Cocoa Cream Sweetener DRY Tea Co ff ee 10 20 30 25 15 5 0 40 35
38. ☕ Complexity of the CoffeeMachine class over time Rehydrate Extract Classes Introduce Factory Whipped Cream Cocoa Cream Sweetener DRY Tea Co ff ee 10 20 30 25 15 5 0 40 35
39. ☕ Complexity of the application Class Churn Complexity --------------------- ----- ---------- CoffeeMachine#vend 10 3.9 BeverageFactory#build 2 6.2 Coffee#prepare 1 16.6 Tea#prepare 1 11.8 Cocoa#prepare 1 8.1 NullBeverage#prepare 1 0.0
40. How to add functionality without modifying existing fi les. Now, who wants ?
41. ☕ Refactor: Use convention to prevent churn class CoffeeMachine def vend(drink: :coffee, options: {}) BeverageFactory.build(drink, options).prepare end end class BeverageFactory def self.build(drink, options) klass = drink.capitalize if Module.const_defined?(klass) Module.const_get(klass).new(options: options) else NullBeverage.new(options: options) end end end class NullBeverage def prepare # no-op end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
42. ☕ Refactor: Use convention to prevent churn class CoffeeMachine def vend(drink: :coffee, options: {}) BeverageFactory.build(drink, options).prepare end end class BeverageFactory def self.build(drink, options) klass = drink.capitalize if Module.const_defined?(klass) Module.const_get(klass).new(options: options) else NullBeverage.new(options: options) end end end class NullBeverage def prepare # no-op end end class Soup def prepare dispense_cup heat_water dispense_condensed_soup dispense_water dispense_croutons if options[:crunchy] dispense_hot_sauce if options[:spicy] end end class Coffee def prepare dispense_cup heat_water prepare_grounds dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] dispense_whipped_cream if options[:fluffy] dispose_of_grounds end end class Tea def prepare dispense_cup heat_water dispense_tea_bag dispense_water dispense_sweetener if options[:sweet] dispense_creamer if options[:creamy] end end class Cocoa def prepare dispense_cup heat_water dispense_cocoa_mix dispense_water dispense_whipped_cream if options[:fluffy] end end
43. Yeah, but does it scale? How to apply this to a large, complicated code base.
44. ☕ Plotting complexity vs. churn Churn Complexity Getting Empirical about Refactoring by Michael Feathers
45. ☕ Plotting complexity vs. churn Pain Free Churn Complexity
46. ☕ Plotting complexity vs. churn Pain Free Painful Churn Complexity
47. Pain Free ☕ Plotting complexity vs. churn Painful Configuration? Churn Complexity
48. ☕ Plotting complexity vs. churn Pain Free Painful Configuration? Omega Mess? Churn Complexity Go Ahead, Make a Mess by Sandi Metz
49. ☕ Plotting complexity vs. churn Churn Complexity
50. Conclusion A Brewer’s Guide to Filtering out Complexity and Churn
51. Take Aways A Brewer’s Guide to Filtering out Complexity and Churn
52. Take Aways A Brewer’s Guide to Filtering out Complexity and Churn Complexity will sneak into your code. • Happens one commit at a time • Conditionals and DRY are often the culprits
53. Take Aways A Brewer’s Guide to Filtering out Complexity and Churn You can recognize complexity before it becomes painful. • Keep methods short • Watch complexity • Pay attention to how it feels Complexity will sneak into your code. • Happens one commit at a time • Conditionals and DRY are often the culprits
54. Take Aways A Brewer’s Guide to Filtering out Complexity and Churn You can recognize complexity before it becomes painful. • Keep methods short • Watch complexity • Pay attention to how it feels And, you can back away from painful complexity. • Polymorphism and factories are your friends • Overly DRY code can hide abstractions and couple algorithms in dangerous ways Complexity will sneak into your code. • Happens one commit at a time • Conditionals and DRY are often the culprits
55. Homework A Brewer’s Guide to Filtering out Complexity and Churn
56. Homework What is the average method complexity for your application? • Use the Flog gem to measure complexity A Brewer’s Guide to Filtering out Complexity and Churn
57. Homework What is the fi le with the most churn in your application? • Use the Churn gem to measure churn What is the average method complexity for your application? • Use the Flog gem to measure complexity A Brewer’s Guide to Filtering out Complexity and Churn
58. Homework What is the fi le with the most churn in your application? • Use the Churn gem to measure churn Which class in your application needs the most attention? • Use the Ruby Critic gem to plot complexity vs. churn • Look for the fi le with the highest complexity and churn What is the average method complexity for your application? • Use the Flog gem to measure complexity A Brewer’s Guide to Filtering out Complexity and Churn
59. EMAIL fi to@meraki.net
 GITHUB @Fito TWITTER @ fi to.vonzastrow EMAIL alan@meraki.net GITHUB @aridlehoover
 TWITTER @aridlehoover BLOG the.codegardener.com GITHUB REPO https://github.com/ fi rst-try-software/co ff ee Get in touch! SLACK CHANNEL #a-brewers-guide-to- fi ltering-out-complexity-and-churn
60. Ruby Flog Ruby Flog VS Code extension that puts fl og scores in your status bar
61. Thanks for coming! A Brewer’s Guide to Filtering out Complexity and Churn Sandi Metz • Practical Object Oriented Design in Ruby (book) • 99 Bottles of OOP (book) (sample on the topic of measuring complexity) • Rules: https://youtu.be/npOGOmkxuio • Go Ahead, Make a Mess: https://youtu.be/mpA2F1In41w Ryan Davis • Flog: https://github.com/seattlerb/ fl og Jake Scruggs • https://jakescruggs.blogspot.com/2008/08/whats-good- fl og-score.html Michael Feathers • Working E ff ectively with Legacy Code (book) • https://www.agileconnection.com/article/getting-empirical-about-refactoring Alan Ridlehoover & Fito von Zastrow • Ruby Flog: https://marketplace.visualstudio.com/items?itemName= fi rst-try-software.ruby- fl og