Make Ruby Write Your Code For You

Despite best intentions, sometimes you just have to write similar code over and over again. This leads to a massive maintenance burden down the road. But, there’s a better way: have the computer write the code for you.

Code generators are shrouded in mystery and can sound unapproachable, but they aren’t! I’ll show you how code generation is no different than web development and why Ruby has all of the tools to build one quickly. You’ll leave this talk knowing where you could apply code generation in your own code base and how to get started!

Transcript

1. Make Ruby Write Your Code For You Alex Stephen @rambleraptor
3. github.com/googlecloudplatform/ magic-modules
5. Auto-generation: Computer writes code for you
7. Auto-generation: You tell the computer what to write
8. Auto-generation: You tell the computer how to write it
9. Auto-generation: The computer writes what you want where you want it
11. Auto-generation: “Write once, write anywhere****”
13. Preface: Mad Libs The _______ ran up the _______. (noun) (noun) Then, it ________ jumped ______ the chair. (adverb) (preposition) Nouns: cat, dog, mouse, hill Adverbs: angrily, sadly Preposition: under, around Template Word Bank
14. Mad Libs End Result The cat ran up the mouse. Then, it angrily jumped around the chair. The mouse ran up the dog. Then, it sadly jumped under the chair. The cat ran up the hill. Then, it sadly jumped around the chair. The mouse ran up the cat. Then, it angrily jumped under the chair. The dog ran up the hill. Then, it sadly jumped under the chair. The cat ran up the dog. Then, it sadly jumped around the chair. The cat ran up the mouse. Then, it angrily jumped under the chair. The hill ran up the dog. Then, it angrily jumped around the chair. dot dot dot
15. Let’s try something more code related a = _____.new() food a.add(_________) topping a.order() Template Word Bank Pizza Salad Breadsticks Pepperoni Sausage Lettuce Gummy Bears Bread Sticks API Name (Food name) API Options (Ingredients)
16. Let’s try something code centric a = Pizza.new() a.add(“sausage”) a.order() a = Pizza.new() a.add(“pepperoni”) a.order() a = Breadsticks.new() a.add(“bread”) a.order() a = Breadsticks.new() a.add(“sticks”) a.order() dot dot dot a = Salad.new() a.add(“lettuce”) a.order() a = Salad.new() a.add(“carrots”) a.order()
17. Auto-generation is just like Mad Libs!
18. • No blockchain! • No machine learning! • No compiler magic! What auto-generation isn’t (for us)
19. When should I use this?
20. Abstractions
24. Functions provide code reuse
25. Functions provide abstraction over functionality actions
27. Classes provide abstraction over things
28. Classes provide abstraction over inputs
32. We don’t have a way to fix the copy-paste problem
33. We don’t have a way to abstract for similar functionality
34. We don’t have a way to abstract for similar functionality at scale
36. Adding new features by hand takes roughly the same amount of time (except tech debt)
37. Adding new features by auto-generation takes tons of time at first, but eventually it pays off
38. • Lots of similar-looking code • The overhead of building out your templates + framework makes sense • You still might be writing some code manually • Once you start auto-generating, there’s no going back... When do you auto-generate?
40. Ruby!
41. • Can define a word bank • Build out some human-readable templates • Injects values into templates We need a tool that:
42. Templates
43. ERB! require ‘erb’
44. ERB! require ‘erb’
45. What if my template looked like Ruby code?
48. How does this differ from web-dev? • You want as much logic in your templates as possible • Templates should be human readable! Don’t be too clever
49. Word Bank
50. • Contain everything needed in your templates • Something loopable • May have to contain some custom code • Reverse engineer your word bank from your templates Word Bank
51. YAML! YAML.load()
52. YAML! YAML.load()
53. YAML! YAML.load()
55. • Initializers are never called! • You can add anything anywhere! • Potential for bad security issues • TLDR; there are no rules Caveats in YAML
56. • Initializers are never called! • You can add anything anywhere! • Potential for bad security issues • TLDR; there are no rules Caveats in YAML
57. • Code generation is like Mad Libs • Template that looks like code • Word Bank of the things that you’re generating • Runner that combines the two TL;DR
58. Thank you! twitter.com/rambleraptor github.com/rambleraptor speakerdeck.com/rambleraptor github.com/googlecloudplatform/magic-modules