Ruby Book Club LIVE

Hello and welcome to the Ruby Book Club! We’re delighted that you could join us.

Today we’re starting with section 4.9 in Avdi Grimm’s ‘Confident Ruby’: Replace “string typing” with classes.

As always, it doesn’t matter if you haven’t found time to do the reading. At the Ruby Book Club, we like to make sure that everyone is on the same page.

Transcript

1. Ruby Book Club
   
   LIVE
   Nadia Odunayo
   @nodunayo
   @rubybookclub
   

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2. 1 hour of a
   Ruby book
   each week
   

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3. @saronyitbarek
   codenewbie.org
   

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4. @nodunayo
   ignition.works
   

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6. 4.9
   Replace “string typing”
   with classes
   

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7. Interactive!
   

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8. What did
   
   you make of the
   reading?
   

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9. Who’s done the
   reading?
   

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12. Let’s get started!
    

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13. “The string is a stark data structure…a
    perfect vehicle for hiding information.”
    — Alan Perlis
    p.84
    

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14. Alan J. Perlis
    (April 1, 1922 – February 7, 1990)
    

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15. String Typing
    

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16. Replace strings that have special
    meanings with user-defined types.”
    p.84
    

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17. Input data is represented as a
    specially-formatted String.
    p.84
    

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18. Input data is represented as a
    specially-formatted String.
    There are numerous case statements
    switching on the content of the
    String.
    p.84
    

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19. Polymorphism
    

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20. p.85
    

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28. Can you spot any
    problems with this
    code?
    

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32. p.87
    

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33. light = TrafficLight.new
    p.87
    

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34. light = TrafficLight.new
    light.change_to(“PROCEED”)
    p.87
    

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35. light = TrafficLight.new
    light.change_to(“PROCEED”)
    puts “Next state: #{light.next_state.inspect}”
    p.87
    

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36. Next state: nil
    

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38. Next state: nil
    

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39. None of the case
    statements end with
    else clauses.
    p.87
    

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42. Something doesn’t feel
    right…
    

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43. …so what can we do
    about it?
    

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44. What if we
    represented traffic
    light states as
    objects?
    

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49. So, let’s get rid of that
    other case statement…
    

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50. p.92
    

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51. Subclasses
    

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55. Conclusion
    

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56. There were repetitive
    case statements all
    switching on the same
    variable.
    p.96
    

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57. It was too easy to
    introduce an invalid
    value for the @state
    variable.
    p.96
    

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58. “traffic light state”
    p.96
    

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59. “The key to working productively in an
    OO language is to make the type
    system and polymorphic method
    dispatch do the work for you.”
    
    — Avdi Grimm
    p.96
    

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60. Wrap up
    

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61. See you next
    week?
    

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62. Do I need to
    convince you to
    come back next
    week?
    

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63. Here’s the thing…
    

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64. How do we
    
    level up
    
    as developers?
    

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65. Read books
    

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66. How many technical
    books have you
    
    finished?
    

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67. Being in a book
    club is the answer.
    

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68. Focus
    

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69. Review
    

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70. Fun
    

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71. Being in a book
    club is the answer.
    

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72. Being in the Ruby
    Book Club is the
    answer.
    

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74. CRBOOKCLUB
    20% off
    confidentruby.com
    

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75. Subscribe
    

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76. rubybookclub.com
    

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77. @rubybookclub
    

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78. See you next week.
    

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79. See you next week.
    Nadia Odunayo
    @nodunayo
    @rubybookclub
    Thank you!
    rubybookclub.com
    

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