less-code-20-min-wide-theorem_local.pdf

Where do simplicity and code meet? This presentation is an attempt to show why certain tools can be considered simple, minimalistic, or otherwise part of the less code culture.

Transcript

1. Less code, more confidence Lucas "Tonchis" Tolchinsky
2. Less code, more confidence Lucas "Tonchis" Tolchinsky
3. I hate debugging
4. feeling lost in code
5. legacy code
6. nobody knows how it works
7. less code
8. libraries over frameworks
9. what makes a library simple?
10. where is the less code?
11. Agenda • Readability • Explicit is better than implicit • Avoiding redundancy
12. disclaimer!
13. people != code
14. Readability
15. code has two purposes
16. tell computers what to do
17. explain to humans how it's done
18. assert-url 1 def test_foo 2 post "/foo" 3 4 assert_equal 201, last_response.status 5 assert_equal "http://localhost:8080/foo/1", 6 last_response.location 7 end
19. assert-url 1 include AssertUrl 2 3 def test_foo 4 post "/foo" 5 6 assert_equal 201, last_response.status 7 assert_path_equal "/foo/1", last_response.location 8 end
20. assert-url 1 module AssertUrl 2 PARTS = %W[scheme host port path query fragment] 3 4 PARTS.each do |part| 5 error = const_set("#{part.capitalize}Error", Class.new(StandardError)) 6 7 define_method(:"assert_#{part}_equal") do |expected, value| 8 expected = normalize(part, expected) 9 value = urify(value).send(part.to_sym) 10 11 expected == value || (raise error, "expected #{expected}, got #{value}") 12 end 13 end 53 end
21. why write it this way?
22. optimized for? who is this code
23. assert-url 1 module AssertUrl 2 PARTS = %W[scheme host port path query fragment] 3 4 PARTS.each do |part| 5 error = const_set("#{part.capitalize}Error", Class.new(StandardError)) 6 7 define_method(:"assert_#{part}_equal") do |expected, value| 8 expected = normalize(part, expected) 9 value = urify(value).send(part.to_sym) 10 11 expected == value || (raise error, "expected #{expected}, got #{value}") 12 end 13 end 53 end
24. assert-url 1 module AssertUrl 2 PARTS = %W[scheme host port path query fragment].each do |part| 3 const_set("#{part.capitalize}Error", Class.new(StandardError)) 4 end 5 6 def assert_scheme_equal(expected, value) 7 value = urify(value).scheme 8 9 expected.to_s == value || raises(SchemeError, expected, value) 10 end 11 12 def assert_host_equal(expected, value) 13 value = urify(value).host 14 15 expected == value || raises(HostError, expected, value) 16 end 137 end
25. why is this better?
26. reading > writing
27. easier to load into your head
28. less legacy code
30. Explicit is better than implicit
31. what we choose to show
32. what we choose to hide
33. abstraction
34. Devise 1 require "devise" 2 3 # In the model 4 class User 5 devise :database_authenticatable 6 end 7 8 # In the controller 9 class ApplicationController < ActionController::Base 10 before_action :authenticate_user! 11 end
35. this is practical, but...
36. dangerous abstraction
37. Devise 1 require "devise" 2 3 # In the model 4 class User 5 devise :database_authenticatable 6 end 7 8 # In the controller 9 class ApplicationController < ActionController::Base 10 before_action :authenticate_user! 11 end
38. Devise 112 def self.define_helpers(mapping) #:nodoc: 113 mapping = mapping.name 114 115 class_eval <<-METHODS, __FILE__, __LINE__ + 1 116 def authenticate_#{mapping}!(opts={}) 117 opts[:scope] = :#{mapping} 118 warden.authenticate!(opts) if !devise_controller? || opts.delete(:force) 119 end 120 METHODS 121 end https://github.com/plataformatec/devise/blob/c9a2d0654e9fc1aaebe6f99ef6fbc55c55a91fdd/lib/devise/controllers/helpers.rb#L112 112 def self.define_helpers(mapping) #:nodoc: 113 mapping = mapping.name 114 115 class_eval <<-METHODS, __FILE__, __LINE__ + 1 116 def authenticate_#{mapping}!(opts={}) 117 opts[:scope] = :#{mapping} 118 warden.authenticate!(opts) if !devise_controller? || opts.delete(:force) 119 end 120 METHODS 121 end
39. learning in the worst moment possible
40. Shield 1 # In the model 2 class User 3 include Shield::Model 4 5 def self.fetch(username) 6 # Find user 7 end 8 end 9 10 # In the controller/routes 11 @user = User.authenticate("tonchis", "pass1234")
41. Shield https://github.com/cyx/shield/blob/40e573a23f07aeb6d88adc2c36967ca67c5aa018/lib/shield.rb#L78-L84 78 def authenticate(username, password) 79 user = fetch(username) 80 81 if user and is_valid_password?(user, password) 82 return user 83 end 84 end 78 def authenticate(username, password) 79 user = fetch(username) 80 81 if user and is_valid_password?(user, password) 82 return user 83 end 84 end
42. the strategy is explicit
43. black magic!
44. less legacy code
46. > La perfection est atteinte, non pas lorsqu'il n'y a plus rien à ajouter, mais lorsqu'il n'y a plus rien à retirer. - Antoine de Saint-Exupéry
47. Avoiding redundancy
48. flexibility is a double-edged sword
49. harder to write homogenous code
50. homogenous code is predictable
51. predictable code is more readable
52. homogenous code is an old quest
53. Fat 1 require "fat" 2 3 hash = { 4 "foo" => { 5 "bar" => { 6 "baz" => "value", 7 }, 8 }, 9 } 10 11 hash["foo"]["not"]["baz"] # undefined method [] for nil 12 13 Fat.at(hash, "foo", "not", "baz") # Fat::FatError: "foo.not" is nil 14 15 Fat.at(hash, "foo.bar.baz") # When keys are Strings. 16 17 Fat.at(hash, "foo:bar:baz") # When keys are Symbols. 1 require "fat" 2 3 hash = { 4 "foo" => { 5 "bar" => { 6 "baz" => "value", 7 }, 8 }, 9 } 10 11 hash["foo"]["not"]["baz"] # undefined method [] for nil 12 13 Fat.at(hash, "foo", "not", "baz") # Fat::FatError: "foo.not" is nil 14 15 Fat.at(hash, "foo.bar.baz") # When keys are Strings. 16 17 Fat.at(hash, "foo:bar:baz") # When keys are Symbols.
54. Fat https://gitlab.com/tonchis/fat/blob/v1.0.0/ext/fat/fat.c#L63 63 static inline void parse_fields(VALUE args, VALUE *fields) { 64 if (RARRAY_LEN(args) == 1) { 65 *fields = rb_str_split(RARRAY_PTR(args)[0], "."); 66 67 if (RARRAY_LEN(*fields) == 1) { 68 VALUE split = rb_str_split(RARRAY_PTR(args)[0], ":"); 69 70 if (RARRAY_LEN(split) == 1) { 71 rb_raise(rb_eFatError, "Single argument expected..."); 72 } else { 73 for (long i = 0; i < RARRAY_LEN(split); i++) { 74 rb_ary_store(*fields, i, str_to_sym(RARRAY_AREF(split, i))); 75 } 76 } 77 } 78 } else { 79 *fields = args; 80 } 81 }
55. has nothing to do with Hash navigation
56. Is it worth it? More work for the reader to understand.
57. Is it worth it? More room for bugs or attack vectors.
58. can we live without the feature?
59. how can we find redundancy?
60. are all my users using 100% of the code?
61. code coverage
62. interface coverage
63. Cuba 1 require "cuba" 2 3 # This block catches `GET /home` 4 Cuba.define do 5 on "home" do 6 on get do 7 res.write("I'm home!") 8 end 9 end 10 end
64. Cuba 1 require "cuba" 2 3 # Which is the same as this one 4 Cuba.define do 5 on get do 6 on "home" do 7 res.write("I'm home!") 8 end 9 end 10 end
65. Cuba 1 require "cuba" 2 3 # And the same as this other one 4 Cuba.define do 5 on get, "home" do 6 res.write("I'm home!") 7 end 8 end
66. Cuba https://github.com/soveran/cuba/blob/1dce54d0926c5d6e5daab033a8e9685c6faa4227/lib/cuba.rb#L167 167 def on(*args, &block) 168 try do 169 @captures = [] 170 171 return unless args.all? { |arg| match(arg) } 172 173 yield(*captures) 174 175 if res.status.nil? 176 if res.body.empty? 177 res.status = 404 178 else 179 res.headers[CONTENT_TYPE] ||= DEFAULT_CONTENT_TYPE 180 res.status = 200 181 end 182 end 183 184 halt(res.finish) 185 end 186 end 167 def on(*args, &block) 168 try do 169 @captures = [] 170 171 return unless args.all? { |arg| match(arg) } 172 173 yield(*captures) 174 175 if res.status.nil? 176 if res.body.empty? 177 res.status = 404 178 else 179 res.headers[CONTENT_TYPE] ||= DEFAULT_CONTENT_TYPE 180 res.status = 200 181 end 182 end 183 184 halt(res.finish) 185 end 186 end
67. is this so bad?
68. code conventions!
69. Syro 1 require "syro" 2 3 # This catches `GET /home` 4 Syro.new do 5 on "home" do 6 get do 7 res.write("I'm home!") 8 end 9 end 10 end
70. Syro 1 require "syro" 2 3 # `GET /home` => 404 Not Found 4 Syro.new do 5 get do 6 on "home" do 7 res.write("I'm home!") 8 end 9 end 10 end
71. Syro https://github.com/soveran/syro/blob/1.0.0/lib/syro.rb#L176-L182 176 def get 177 if root? && req.get? 178 yield 179 180 halt(res.finish) 181 end 182 end 176 def get 177 if root? && req.get? 178 yield 179 180 halt(res.finish) 181 end 182 end
72. more predictable code
73. less legacy code
75. less code • Optimize for readability • Make your solutions explicit • Avoid redundant interfaces
76. thank you!