Rails on Ruby: How Ruby Makes Rails Great

Ruby puts the Ruby in “Ruby on Rails”! It’s the Ruby language that makes Rails flexible, powerful, and with a developer-friendly API. How does Rails take advantage of Ruby’s flexibility and metaprogramming to make it so useful? And how can you take advantage of those features in your Rails app? We’ll go over a few specific Ruby features, like how Rails uses Modules, or `define_method` or `instance_eval`. You’ll be able to use these features to make your app as powerful as Rails itself.

Transcript

1. This slide intentionally left self- promotional https://pragprog.com/ titles/ruby5 35% off with code RailsConf_Atlanta
2. Let's look at some code
4. Rails.env.production? instead of Rails.env == "production"
5. It's Rails Magic!
6. There's a secret:
7. It's all Ruby
8. Rails on Ruby: How Ruby Makes Rails Great Noel Rappin (@noelrap@ruby.social) https://www.chime.com http://noelrappin.com
9. 5 Ruby tricks in the Rails codebase
10. We're not going to explain all of Rails' internals
11. We're also not going to be defensive about Rails design
12. Act 1: String Inquirer
14. method_missing the method of last resort
15. Allows you to parse the method name
16. Rails used to use this for AR record finders find_all_by_name_and_email
17. If the method name ends in ? compare it to the value of the string Rails.env.production?
18. respond_to_missing?
19. Why do this?
20. Flexible to new environments
21. Encapsulates knowledge of internals
22. Act 2: View Assigns
23. Here's some code...
24. instance_variables returns a list: ["@user", "@country"]
25. returns a hash: {user: "Noel", country: "USA"}
26. And some other code
27. instance_variable_set("@user", "Noel")
28. Easy to use by devs (Especially if you don't think about it)
29. Act 3: Callbacks
31. define_method
34. This is part of the code
35. Used by Controllers ActiveJob ActionCable ActiveRecord
36. Easy to implement new callback hooks
37. Act 4: Dirty
38. ActiveRecord::Dirty API > user.zip_code = "60015" > user.zip_code_changed? true > user.zip_code_was "02134"
40. included
43. Looks for a pattern match
44. first_name_was becomes attribute_was(:first_name)
46. Also used for ? and =
47. AR doesn't like looking up attribute names
48. Act 5: Migrations
50. class_eval
51. Makes reversible migrations very easy
52. Conclusion: Why is Rails like this?
53. We have to talk about discoverability
54. The "Look up Definition" IDE button doesn't work
55. One Neat Trick source_location > ApplicationController.method(:before_action).source_location => ["[REDACTED]/actionpack-7.0.4/lib/abstract_controller/callbacks.rb", 204]
56. Flexible
57. Generalizable
58. Developer experience
59. When can you adopt these methods
60. This slide intentionally left self-promotional https://pragprog.com/ titles/ruby5 35% off with code RailsConf_Atlanta @noelrap@ruby.social noelrappin.com