A Brewer's Guide to Filtering out Complexity and Churn

RubyConf Mini 2022 presentation by Alan Ridlehoover & Fito von Zastrow

Abstract
Mechanical coffee machines are amazing! You drop in a coin, listen for the clink, make a selection, and the machine springs to life, hissing, clicking, and whirring. Then the complex mechanical ballet ends, splashing that glorious, aromatic liquid into the cup. Ah! C’est magnifique!

There’s just one problem. Our customers also want soup! And, our machine is not extensible. So, we have a choice: we can add to the complexity of our machine by jamming in a new dispenser with each new request; or, we can pause to make our machine more extensible before development slows to a halt.

Pitch
We contend that:
* Complex code is expensive and risky to change.
* Most programmers are unaware of how their changes increase complexity over time.
* Most programmers add code by mimicking existing code (i.e. complex code begets more complex code).
* Eventually, ignored complexity leads to programmer pain and frustration.
* Without understanding how they arrived at this place, programmers tend to blame their tools, including Ruby.

This talk helps audience members fall in love with Ruby again by showing:
* How complexity sneaks into a code base
* How to recognize that complexity before it gets painful
* How to refactor code away from that pain and frustration

Transcript

1. Alan Ridlehoover & Fito von Zastrow
   RubyConf Mini 2022
   The Coffee
   Machine Talk
   A Brewer’s Guide to Filtering out
   Complexity and Churn
   

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2. PRONOUNS
   
   he/him/his
   
   HOMETOWN
   
   Asunción

   RUBY EXPERIENCE
   
   12 years
   
   FAVORITE COFFEE
   
   Ghirardelli Dark
   Chocolate Mocha
   PRONOUNS
   
   he/him/his
   
   HOMETOWN
   
   Seattle

   RUBY EXPERIENCE
   
   12 years
   
   FAVORITE COFFEE
   
   New Orleans Cold
   Brew w/ Chicory
   

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3. View Slide

4. 🤲
   

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5. View Slide

6. View Slide

7. 👍
   

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8. How did we get here?
   How complexity sneaks into a code base.
   

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9. ☕ Story: As a patron, I want coffee
   class CoffeeMachine
   
   
   def vend
   
   
   dispense_cup
   
   
   heat_water
   
   
   prepare_grounds
   
   
   dispense_water
   
   
   dispose_of_grounds
   
   
   end
   
   
   end
   

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10. ☕ Story: As a patron, I want tea
    class CoffeeMachine
    
    
    def vend(drink: :coffee)
    
    
    if drink == :coffee
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispose_of_grounds
    
    
    elsif drink == :tea
    
    
    dispense_cup
    
    
    dispense_tea_bag
    
    
    heat_water
    
    
    dispense_water
    
    
    end
    
    
    end
    
    
    end
    

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11. ☕ Refactor: DRY up the code
    class CoffeeMachine
    
    
    def vend(drink: :coffee)
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    
    
    

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12. ☕ Story: As a patron, I want sweetener
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    

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13. ☕ Story: As a patron, I want cream
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_cream if options[:creamy]
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    
    
    

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14. ☕ Story: As a patron, I want cocoa
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    

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15. ☕ Story: As a patron, I want whipped cream
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    unless drink == :tea
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    

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16. Do you smell that?
    How to recognize the problem before it
    becomes painful and frustrating.
    Rules by Sandi Metz Flog by Ryan Davis
    

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17. ☕ Measuring complexity with the flog gem
    Score of Means
    
    
    - - - - - - - - - - - - - - - - - - - - - - - - -
    
    
    0-10 Awesome
    
    
    11-20 Good enough
    
    
    21-40 Might need refactoring
    
    
    41-60 Possible to justify
    
    
    61-100 Danger
    
    
    100-200 Whoop, whoop, whoop
    
    
    200 + Someone please think of the children
    
    
    (note: these are scores for an individual method)
    
    
    What's a good
    fl
    og score? by Jake Scruggs
    

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18. ☕ Story: As a patron, I want coffee
    class CoffeeMachine
    
    
    def vend
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    Churn
    
    1
    Complexity
    
    5.5
    10
    20
    30
    25
    15
    5
    0
    

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19. ☕ Story: As a patron, I want tea
    class CoffeeMachine
    
    
    def vend(drink: :coffee)
    
    
    if drink == :coffee
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispose_of_grounds
    
    
    elsif drink == :tea
    
    
    dispense_cup
    
    
    dispense_tea_bag
    
    
    heat_water
    
    
    dispense_water
    
    
    end
    
    
    end
    
    
    end
    Churn
    
    2
    Complexity
    
    14.6
    10
    20
    30
    25
    15
    5
    0
    

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20. ☕ Refactor: DRY up the code
    class CoffeeMachine
    
    
    def vend(drink: :coffee)
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    
    
    Churn
    
    3
    Complexity
    
    10.9
    10
    20
    30
    25
    15
    5
    0
    

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21. ☕ Story: As a patron, I want sweetener
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    Churn
    
    4
    Complexity
    
    13.5
    10
    20
    30
    25
    15
    5
    0
    

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22. ☕ Story: As a patron, I want cream
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    end
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_cream if options[:creamy]
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    
    
    Churn
    
    5
    Complexity
    
    16.0
    10
    20
    30
    25
    15
    5
    0
    

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23. ☕ Story: As a patron, I want cocoa
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    Churn
    
    6
    Complexity
    
    21.3
    10
    20
    30
    25
    15
    5
    0
    

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24. ☕ Story: As a patron, I want whipped cream
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    unless drink == :tea
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    Churn
    
    7
    Complexity
    
    25.5
    10
    20
    30
    25
    15
    5
    0
    

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25. ☕ CoffeeMachine Pain Index over time
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    unless drink == :tea
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    Churn
    
    7
    Complexity
    
    25.5
    10
    20
    30
    25
    15
    5
    0
    

    View Slide

26. ☕ CoffeeMachine Pain Index over time
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    unless drink == :tea
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    Churn
    
    7
    Complexity
    
    25.5
    10
    20
    30
    25
    15
    5
    0
    

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27. Can we turn it around?
    How to
    fi
    lter out complexity and churn.
    

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28. ☕ Refactor: Rehydrate to see missing abstractions
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    dispense_cup
    
    
    heat_water
    
    
    if drink == :coffee
    
    
    prepare_grounds
    
    
    elsif drink == :tea
    
    
    dispense_tea_bag
    
    
    elsif drink == :cocoa
    
    
    dispense_cocoa_mix
    
    
    end
    
    
    dispense_water
    
    
    unless drink == :cocoa
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    unless drink == :tea
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    dispose_of_grounds if drink == :coffee
    
    
    end
    
    
    end
    

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29. ☕ Refactor: Rehydrate to see missing abstractions
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    if drink == :coffee
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    elsif drink == :tea
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    elsif drink == :cocoa
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    
    
    end
    

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30. ☕ Refactor: Extract polymorphic objects
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    if drink == :coffee
    
    
    Coffee.new(options: options).prepare
    
    
    elsif drink == :tea
    
    
    Tea.new(options: options).prepare
    
    
    elsif drink == :cocoa
    
    
    Cocoa.new(options: options).prepare
    
    
    end
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

    View Slide

31. ☕ Refactor: Extract polymorphic objects
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    if drink == :coffee
    
    
    Coffee.new(options: options).prepare
    
    
    elsif drink == :tea
    
    
    Tea.new(options: options).prepare
    
    
    elsif drink == :cocoa
    
    
    Cocoa.new(options: options).prepare
    
    
    end
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

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32. ☕ Refactor: Extract factory class
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    BeverageFactory.build(drink, options).prepare
    
    
    end
    
    
    end
    
    
    class BeverageFactory
    
    
    def self.build(drink, options)
    
    
    if drink == :coffee
    
    
    Coffee.new(options: options)
    
    
    elsif drink == :tea
    
    
    Tea.new(options: options)
    
    
    elsif drink == :cocoa
    
    
    Cocoa.new(options: options)
    
    
    end
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

    View Slide

33. ☕ Refactor: Extract factory class
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    BeverageFactory.build(drink, options).prepare
    
    
    end
    
    
    end
    
    
    class BeverageFactory
    
    
    def self.build(drink, options)
    
    
    if drink == :coffee
    
    
    Coffee.new(options: options)
    
    
    elsif drink == :tea
    
    
    Tea.new(options: options)
    
    
    elsif drink == :cocoa
    
    
    Cocoa.new(options: options)
    
    
    else
    
    
    NullBeverage.new(options: options)
    
    
    end
    
    
    end
    
    
    end
    
    
    class NullBeverage
    
    
    def prepare
    
    
    # no-op
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

    View Slide

34. ☕ Refactor: Use convention to prevent churn
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    BeverageFactory.build(drink, options).prepare
    
    
    end
    
    
    end
    
    
    class BeverageFactory
    
    
    def self.build(drink, options)
    
    
    klass = drink.capitalize
    
    
    if Module.const_defined?(klass)
    
    
    Module.const_get(klass).new(options: options)
    
    
    else
    
    
    NullBeverage.new(options: options)
    
    
    end
    
    
    end
    
    
    end
    
    
    class NullBeverage
    
    
    def prepare
    
    
    # no-op
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

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35. ☕ Complexity of the CoffeeMachine class over time
    Rehydrate
    Extract Classes
    Introduce Factory
    Whipped Cream
    Cocoa
    Cream
    Sweetener
    DRY
    Tea
    Co
    ff
    ee
    10
    20
    30
    25
    15
    5
    0
    40
    35
    

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36. ☕ Complexity of the CoffeeMachine class over time
    Rehydrate
    Extract Classes
    Introduce Factory
    Whipped Cream
    Cocoa
    Cream
    Sweetener
    DRY
    Tea
    Co
    ff
    ee
    10
    20
    30
    25
    15
    5
    0
    40
    35
    

    View Slide

37. ☕ Complexity of the CoffeeMachine class over time
    Rehydrate
    Extract Classes
    Introduce Factory
    Whipped Cream
    Cocoa
    Cream
    Sweetener
    DRY
    Tea
    Co
    ff
    ee
    10
    20
    30
    25
    15
    5
    0
    40
    35
    

    View Slide

38. ☕ Complexity of the CoffeeMachine class over time
    Rehydrate
    Extract Classes
    Introduce Factory
    Whipped Cream
    Cocoa
    Cream
    Sweetener
    DRY
    Tea
    Co
    ff
    ee
    10
    20
    30
    25
    15
    5
    0
    40
    35
    

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39. ☕ Complexity of the application
    Class Churn Complexity
    
    
    --------------------- ----- ----------
    
    
    CoffeeMachine#vend 10 3.9
    
    
    BeverageFactory#build 2 6.2
    
    
    Coffee#prepare 1 16.6
    
    
    Tea#prepare 1 11.8
    
    
    Cocoa#prepare 1 8.1
    
    
    NullBeverage#prepare 1 0.0
    

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40. How to add functionality without modifying existing
    fi
    les.
    Now, who wants ?
    

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41. ☕ Refactor: Use convention to prevent churn
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    BeverageFactory.build(drink, options).prepare
    
    
    end
    
    
    end
    
    
    class BeverageFactory
    
    
    def self.build(drink, options)
    
    
    klass = drink.capitalize
    
    
    if Module.const_defined?(klass)
    
    
    Module.const_get(klass).new(options: options)
    
    
    else
    
    
    NullBeverage.new(options: options)
    
    
    end
    
    
    end
    
    
    end
    
    
    class NullBeverage
    
    
    def prepare
    
    
    # no-op
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

    View Slide

42. ☕ Refactor: Use convention to prevent churn
    class CoffeeMachine
    
    
    def vend(drink: :coffee, options: {})
    
    
    BeverageFactory.build(drink, options).prepare
    
    
    end
    
    
    end
    
    
    class BeverageFactory
    
    
    def self.build(drink, options)
    
    
    klass = drink.capitalize
    
    
    if Module.const_defined?(klass)
    
    
    Module.const_get(klass).new(options: options)
    
    
    else
    
    
    NullBeverage.new(options: options)
    
    
    end
    
    
    end
    
    
    end
    
    
    class NullBeverage
    
    
    def prepare
    
    
    # no-op
    
    
    end
    
    
    end
    
    
    class Soup
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_condensed_soup
    
    
    dispense_water
    
    
    dispense_croutons if options[:crunchy]
    
    
    dispense_hot_sauce if options[:spicy]
    
    
    end
    
    
    end
    class Coffee
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    prepare_grounds
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    dispose_of_grounds
    
    
    end
    
    
    end
    
    
    class Tea
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_tea_bag
    
    
    dispense_water
    
    
    dispense_sweetener if options[:sweet]
    
    
    dispense_creamer if options[:creamy]
    
    
    end
    
    
    end
    
    
    class Cocoa
    
    
    def prepare
    
    
    dispense_cup
    
    
    heat_water
    
    
    dispense_cocoa_mix
    
    
    dispense_water
    
    
    dispense_whipped_cream if options[:fluffy]
    
    
    end
    
    
    end
    

    View Slide

43. Yeah, but does it scale?
    How to apply this to a large, complicated code base.
    

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44. ☕ Plotting complexity vs. churn
    Churn
    Complexity
    Getting Empirical about Refactoring by Michael Feathers
    

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45. ☕ Plotting complexity vs. churn
    Pain Free
    Churn
    Complexity
    

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46. ☕ Plotting complexity vs. churn
    Pain Free
    Painful
    Churn
    Complexity
    

    View Slide

47. Pain Free
    ☕ Plotting complexity vs. churn
    Painful
    Configuration?
    Churn
    Complexity
    

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48. ☕ Plotting complexity vs. churn
    Pain Free
    Painful
    Configuration?
    Omega Mess?
    Churn
    Complexity
    Go Ahead, Make a Mess by Sandi Metz
    

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49. ☕ Plotting complexity vs. churn
    Churn
    Complexity
    

    View Slide

50. Conclusion
    A Brewer’s Guide to Filtering out Complexity and Churn
    

    View Slide

51. Take Aways
    A Brewer’s Guide to Filtering out Complexity and Churn
    

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52. Take Aways
    A Brewer’s Guide to Filtering out Complexity and Churn
    Complexity will sneak into your code.
    • Happens one commit at a time
    • Conditionals and DRY are often the culprits
    

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53. Take Aways
    A Brewer’s Guide to Filtering out Complexity and Churn
    You can recognize complexity before it becomes painful.
    • Keep methods short
    • Watch complexity
    • Pay attention to how it feels
    Complexity will sneak into your code.
    • Happens one commit at a time
    • Conditionals and DRY are often the culprits
    

    View Slide

54. Take Aways
    A Brewer’s Guide to Filtering out Complexity and Churn
    You can recognize complexity before it becomes painful.
    • Keep methods short
    • Watch complexity
    • Pay attention to how it feels
    And, you can back away from painful complexity.
    • Polymorphism and factories are your friends
    • Overly DRY code can hide abstractions and couple algorithms in dangerous ways
    Complexity will sneak into your code.
    • Happens one commit at a time
    • Conditionals and DRY are often the culprits
    

    View Slide

55. Homework
    A Brewer’s Guide to Filtering out Complexity and Churn
    

    View Slide

56. Homework
    What is the average method complexity for your application?
    • Use the Flog gem to measure complexity
    A Brewer’s Guide to Filtering out Complexity and Churn
    

    View Slide

57. Homework
    What is the
    fi
    le with the most churn in your application?
    • Use the Churn gem to measure churn
    What is the average method complexity for your application?
    • Use the Flog gem to measure complexity
    A Brewer’s Guide to Filtering out Complexity and Churn
    

    View Slide

58. Homework
    What is the
    fi
    le with the most churn in your application?
    • Use the Churn gem to measure churn
    Which class in your application needs the most attention?
    • Use the Ruby Critic gem to plot complexity vs. churn
    • Look for the
    fi
    le with the highest complexity and churn
    What is the average method complexity for your application?
    • Use the Flog gem to measure complexity
    A Brewer’s Guide to Filtering out Complexity and Churn
    

    View Slide

59. EMAIL
    
    fi
    to@meraki.net

    GITHUB
    
    @Fito
    
    TWITTER
    
    @
    fi
    to.vonzastrow
    EMAIL
    
    alan@meraki.net
    
    GITHUB
    
    @aridlehoover

    TWITTER
    
    @aridlehoover
    
    BLOG
    
    the.codegardener.com
    GITHUB REPO
    
    https://github.com/
    fi
    rst-try-software/co
    ff
    ee
    Get in touch!
    SLACK CHANNEL
    
    #a-brewers-guide-to-
    fi
    ltering-out-complexity-and-churn
    

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60. Ruby Flog
    Ruby Flog
    VS Code extension that puts
    fl
    og scores in your status bar
    

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61. Thanks for coming!
    A Brewer’s Guide to Filtering out Complexity and Churn
    Sandi Metz
    • Practical Object Oriented Design in Ruby (book)
    
    • 99 Bottles of OOP (book) (sample on the topic of measuring complexity)
    
    • Rules: https://youtu.be/npOGOmkxuio
    
    • Go Ahead, Make a Mess: https://youtu.be/mpA2F1In41w
    
    Ryan Davis
    • Flog: https://github.com/seattlerb/
    fl
    og
    Jake Scruggs
    • https://jakescruggs.blogspot.com/2008/08/whats-good-
    fl
    og-score.html
    
    Michael Feathers
    • Working E
    ff
    ectively with Legacy Code (book)
    
    • https://www.agileconnection.com/article/getting-empirical-about-refactoring
    
    Alan Ridlehoover & Fito von Zastrow
    • Ruby Flog: https://marketplace.visualstudio.com/items?itemName=
    fi
    rst-try-software.ruby-
    fl
    og
    
    

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