Don’t Hang Me Out To DRY

Close your eyes and imagine the perfect codebase to work on. I bet you’ll say it has complete test coverage. It’s fully-optimized, both in terms of performance and architectural design. And, of course, it contains only DRY code. Surely we can all agree that this is an aspirational situation. But...do we really want that?

Don’t get me wrong; these qualities are all beneficial. However, if we also think we should value everything in moderation, when should we push back on these ideals? What problems can they introduce? Let’s talk about the exceptions to some of the “rules” we all hold dear.

Transcript

1. Don’t Hang Me Out
   to DRY
   Kevin Murphy
   @kevin_j_m
   

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2. Don’t Hang Me Out
   to DRY
   Kevin Murphy
   @kevin_j_m
   

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3. @kevin_j_m
   vory Tower

   nnovation TechnologY
   

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4. @kevin_j_m
   T
   T
   

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5. @kevin_j_m
   T
   

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6. @kevin_j_m
   T
   our code has
   

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7. @kevin_j_m
   T
   Make work
   

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8. @kevin_j_m
   T
   Make work
   ☂
   

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9. @kevin_j_m
   T
   Make
   T
   work
   Make right
   

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10. @kevin_j_m
    T
    Make right
    
    ❌
    

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11. @kevin_j_m
    T
    Make
    T
    T
    work
    Make
    Make
    right
    fast
    

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12. @kevin_j_m
    T
    Make fast
    
    

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13. @kevin_j_m
    T
    Make
    T
    T
    work
    Make
    Make
    right
    fast
    

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14. @kevin_j_m
    
    

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16. @kevin_j_m
    Kevin Murphy
    

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17. @kevin_j_m
    T
    

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18. @kevin_j_m
    
    Should see 4 testimonials
    today, but only 3 are seen.
    

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19. @kevin_j_m
    def number_testimonials
    if mercury_retrograde?
    4
    elsif full_moon?
    3
    elsif tuesday?
    2
    else
    coin_flip
    end
    end
    

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20. @kevin_j_m
    def number_testimonials
    if mercury_retrograde?
    4
    elsif full_moon?
    3
    elsif tuesday?
    2
    else
    coin_flip
    end
    end
    

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21. @kevin_j_m
    Farmer’s Almanac
    Mercury in Retrograde
    OCT
    31
    NOV
    20
    

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22. @kevin_j_m
    Code Coverage
    

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23. @kevin_j_m
    

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24. @kevin_j_m
    it "shows 4 testimonials if mercury is in retrograde" do
    end
    

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25. @kevin_j_m
    it "shows 4 testimonials if mercury is in retrograde" do
    allow(Mercury).to receive(:in_retrograde?).and_return(true)
    end
    

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26. @kevin_j_m
    it "shows 4 testimonials if mercury is in retrograde" do
    allow(Mercury).to receive(:in_retrograde?).and_return(true)
    display = TestimonialDisplay.new
    end
    

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27. @kevin_j_m
    it "shows 4 testimonials if mercury is in retrograde" do
    allow(Mercury).to receive(:in_retrograde?).and_return(true)
    display = TestimonialDisplay.new
    expect(display.number_testimonials).to eq 4
    end
    

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28. @kevin_j_m
    

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29. @kevin_j_m
    class Mercury
    def self.in_retrograde?(date)
    end
    end
    

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30. @kevin_j_m
    class Mercury
    def self.in_retrograde?(date)
    false
    end
    end
    

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31. @kevin_j_m
    

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32. @kevin_j_m
    Coverage is insufficient
    

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33. @kevin_j_m
    TDD
    

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34. @kevin_j_m
    Pair Programming
    

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35. @kevin_j_m
    Mutation Testing
    

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36. @kevin_j_m
    Code Review
    

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37. @kevin_j_m
    QA
    

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38. @kevin_j_m
    '
    
    

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39. @kevin_j_m
    Coverage is insufficient
    

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40. @kevin_j_m
    Coverage as a goal
    

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41. @kevin_j_m
    Randomized with seed 46917
    .F..
    Failures:
    1) TestimonialDisplay#number_testimonials will show 0 or 1 testimonial
    if no other conditions are met
    Failure/Error: expect(results.uniq).to match_array [0, 1]
    expected collection contained: [0, 1]
    actual collection contained: [1]
    the missing elements were: [0]
    

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42. @kevin_j_m
    def number_testimonials
    if mercury_retrograde?
    4
    elsif full_moon?
    3
    elsif tuesday?
    2
    else
    coin_flip
    end
    end
    

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43. @kevin_j_m
    def coin_flip
    rand(2)
    end
    

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44. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    end
    

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45. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    end
    

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46. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    end
    

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47. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    end
    

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48. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    end
    end
    

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49. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    2.times do
    end
    end
    end
    

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50. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    2.times do
    results << display.number_testimonials
    end
    end
    end
    

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51. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    2.times do
    results << display.number_testimonials
    end
    end
    expect(results.uniq).to match_array [0, 1]
    end
    

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52. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    2.times do
    results << display.number_testimonials
    end
    end
    expect(results.uniq).to match_array [0, 1]
    end
    

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53. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    2.times do
    results << display.number_testimonials
    end
    end
    expect(results.uniq).to match_array [0, 1]
    end
    

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54. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    results = []
    display = TestimonialDisplay.new
    travel_to waning_monday do
    200.times do
    results << display.number_testimonials
    end
    end
    expect(results.uniq).to match_array [0, 1]
    end
    

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55. @kevin_j_m
    it "will show 0 or 1 testimonial" do
    waning_monday = Date.new(2019, 9, 16)
    display = TestimonialDisplay.new
    travel_to waning_monday do
    expect(results.uniq).to be_in [0, 1]
    end
    end
    

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56. @kevin_j_m
    Vanity metric?
    

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57. @kevin_j_m
    

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58. @kevin_j_m
    Coverage is a signal
    

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59. @kevin_j_m
    

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60. @kevin_j_m
    

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61. @kevin_j_m
    

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62. @kevin_j_m
    

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63. @kevin_j_m
    

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64. @kevin_j_m
    Coverage Consideration
    Total Cost of Ownership
    

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65. @kevin_j_m
    T
    

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66. @kevin_j_m
    +
    

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67. @kevin_j_m
    ☑
    Dark Dungeon API Access Keys
    should follow same convention
    

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68. @kevin_j_m
    it "does not provide a company key" do
    end
    

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69. @kevin_j_m
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    end
    

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70. @kevin_j_m
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    end
    

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71. @kevin_j_m
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(COMPANY_REGEX)).not_to eq true
    end
    

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72. @kevin_j_m
    it "appends the user id if the user's id is odd" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :user, user_id: 1)
    expect(key).to end_with("-1")
    end
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(COMPANY_REGEX)).not_to eq true
    end
    it "raises an exception if it doesn't understand the accessor type" do
    generator = AccessKeyGenerator.new
    expect { generator.access_key(accessor_type: :foo) }
    .to raise_error UnknownAccessorType
    end
    end
    end
    

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73. @kevin_j_m
    it "appends the user id if the user's id is odd" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :user, user_id: 1)
    expect(key).to end_with("-1")
    end
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(COMPANY_REGEX)).not_to eq true
    end
    it "raises an exception if it doesn't understand the accessor type" do
    generator = AccessKeyGenerator.new
    expect { generator.access_key(accessor_type: :foo) }
    .to raise_error UnknownAccessorType
    end
    end
    end
    

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74. @kevin_j_m
    RSpec.describe AccessKeyGenerator do
    UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/
    COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/
    describe "#access_key" do
    it "provides a base-64 encoded key if the key is for an acquired company" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company, acquired_company: true)
    expect(key).to eq Base64.strict_encode64(Base64.decode64(key))
    end
    it "creates an ivory tower company access key if it's a company not acquired" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company, acquired_company: false)
    expect(key.match?(COMPANY_REGEX)).to eq true
    end
    it "does not provide a full UUID if the key is for a company" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company)
    

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75. @kevin_j_m
    RSpec.describe AccessKeyGenerator do
    UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/
    COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/
    describe "#access_key" do
    it "provides a base-64 encoded key if the key is for an acquired company" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company, acquired_company: true)
    expect(key).to eq Base64.strict_encode64(Base64.decode64(key))
    end
    it "creates an ivory tower company access key if it's a company not acquired" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company, acquired_company: false)
    expect(key.match?(COMPANY_REGEX)).to eq true
    end
    it "does not provide a full UUID if the key is for a company" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor_type: :company)
    

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76. @kevin_j_m
    DRY Code
    Don’t Repeat Yourself
    

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77. @kevin_j_m
    DAMP Code
    Descriptive And Meaningful
    Phrases
    

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78. @kevin_j_m
    it "does not provide a company key" do
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(COMPANY_REGEX)).not_to eq true
    end
    

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79. @kevin_j_m
    it "does not provide a company key" do
    company_regex = /CO-[0-9a-fA-F]{8}/
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(COMPANY_REGEX)).not_to eq true
    end
    

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80. @kevin_j_m
    it "does not provide a company key" do
    company_regex = /CO-[0-9a-fA-F]{8}/
    generator = AccessKeyGenerator.new
    key = generator.access_key(accessor: :user, user_id: 0)
    expect(key.match?(company_regex)).not_to eq true
    end
    

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81. @kevin_j_m
    T
    

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82. @kevin_j_m
    class AccessKeyGenerator
    def access_key(accessor:, user_id: nil)
    if accessor == :company
    "CO-#{SecureRandom.hex(8)}"
    elsif accessor == :user
    uuid = SecureRandom.uuid
    user_id.odd? ? uuid << “-#{user_id}" : uuid
    end
    end
    end
    

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83. @kevin_j_m
    class AccessKeyGenerator
    def access_key(accessor:, acquired_co: nil, user_id: nil)
    if accessor == :company
    "CO-#{SecureRandom.hex(8)}"
    elsif accessor == :user
    uuid = SecureRandom.uuid
    user_id.odd? ? uuid << “-#{user_id}" : uuid
    end
    end
    end
    

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84. @kevin_j_m
    class AccessKeyGenerator
    def access_key(accessor:, acquired_co: nil, user_id: nil)
    if accessor == :company
    if acquired_co
    SecureRandom.base64
    else
    “CO-#{SecureRandom.hex(8)}”
    end
    elsif accessor == :user
    uuid = SecureRandom.uuid
    user_id.odd? ? uuid << “-#{user_id}" : uuid
    end
    end
    end
    

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85. @kevin_j_m
    DRY Code?
    

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86. @kevin_j_m
    class User < ApplicationRecord
    def generate_access_key
    SecureRandom.uuid
    end
    end
    

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87. @kevin_j_m
    class Company < ApplicationRecord
    def generate_access_key
    SecureRandom.uuid
    end
    end
    

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88. @kevin_j_m
    

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89. @kevin_j_m
    class AccessKeyGenerator
    def access_key
    SecureRandom.uuid
    end
    end
    

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90. @kevin_j_m
    class AccessKeyGenerator
    def access_key(accessor:, user_id: nil)
    if accessor == :company
    "CO-#{SecureRandom.hex(8)}"
    elsif accessor == :user
    uuid = SecureRandom.uuid
    user_id.odd? ? uuid << “-#{user_id}" : uuid
    end
    end
    end
    

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91. @kevin_j_m
    WET Code
    Write Everything Twice
    

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92. @kevin_j_m
    

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93. @kevin_j_m
    class User < ApplicationRecord
    def generate_access_key
    SecureRandom.uuid
    end
    end
    

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94. @kevin_j_m
    class User < ApplicationRecord
    def generate_access_key
    SecureRandom.uuid
    end
    end
    class Company < ApplicationRecord
    def generate_access_key
    SecureRandom.uuid
    end
    end
    

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95. @kevin_j_m
    class User < ApplicationRecord
    def generate_access_key
    if id.odd?
    "#{SecureRandom.uuid}-#{id}"
    else
    SecureRandom.uuid
    end
    end
    end
    

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96. @kevin_j_m
    class User < ApplicationRecord
    def generate_access_key
    if id.odd?
    "#{SecureRandom.uuid}-#{id}"
    else
    SecureRandom.uuid
    end
    end
    end
    class Company < ApplicationRecord
    def generate_access_key
    if acquisition?
    SecureRandom.base64
    else
    "CO-#{SecureRandom.hex(8)}"
    end
    end
    end
    

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97. @kevin_j_m
    DRY Consideration
    Flexibility
    

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98. @kevin_j_m
    T
    

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99. @kevin_j_m
    
    Passing “15” to API
    provides wrong result
    

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100. @kevin_j_m
     Performant Code
     

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101. @kevin_j_m
     Rust
     

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102. @kevin_j_m
     gem 'helix-rails', '~> 0.5.0'
     

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103. @kevin_j_m
     def generate(bound: i32)
     

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104. @kevin_j_m
     def generate(bound: i32) -> Vec {
     }
     

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105. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     }
     

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106. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     }
     }
     

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107. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     })
     }
     }
     

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108. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     })
     }
     }
     

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109. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     })
     }
     }
     

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110. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     })
     }
     }
     

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111. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (2, 4) => "Buzz".to_string(),
     })
     }
     }
     

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112. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (2, 4) => "Buzz".to_string(),
     (_, _) => x.to_string(),
     })
     }
     }
     

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113. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (2, 4) => "Buzz".to_string(),
     (_, _) => x.to_string(),
     })
     }
     results
     }
     

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114. @kevin_j_m
     FBAAS
     

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115. @kevin_j_m
     FBAAS
     FizzBuzz As A Service
     

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116. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (2, 4) => "Buzz".to_string(),
     (_, _) => x.to_string(),
     })
     }
     results
     }
     

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117. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (2, 4) => "Buzz".to_string(),
     (_, _) => x.to_string(),
     })
     }
     results
     }
     

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118. @kevin_j_m
     def generate(bound: i32) -> Vec {
     let mut results = Vec::new();
     for x in 1..(bound+1) {
     results.push(match(x % 3, x % 5) {
     (0, 0) => "FizzBuzz".to_string(),
     (0, _) => "Fizz".to_string(),
     (_, 0) => "Buzz".to_string(),
     (_, _) => x.to_string(),
     })
     }
     results
     }
     

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119. @kevin_j_m
     Performant Consideration
     Weigh observed behavior &
     maintenance
     

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120. @kevin_j_m
     T
     Make
     T
     T
     work
     Make
     Make
     right
     fast
     

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121. @kevin_j_m
     T
     Make work
     for confidence,
     not metrics
     

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122. @kevin_j_m
     T
     Make right
     knowing “right”
     is subjective
     

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123. @kevin_j_m
     T
     Make fast
     when you know
     it’s warranted
     

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124. @kevin_j_m
     https://www.thegnar.co/rubyconf
     https://github.com/kevin-j-m/ivory-tower
     T
     

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125. @kevin_j_m
     https://www.thegnar.co/rubyconf
     

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