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Get a Whiff of This

Get a Whiff of This

A talk about code smells

Sandi Metz

May 06, 2016
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  1. May 2016
    @sandimetz
    Sandi Metz
    Get a Whiff
    of This
    Sandi Metz

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  2. @sandimetz May 2016
    Kent Beck

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  3. @sandimetz May 2016
    Kent Beck Martin Fowler

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  4. @sandimetz May 2016
    Kent Beck Martin Fowler

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  5. @sandimetz May 2016
    Classic Smells

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  6. @sandimetz May 2016
    Classic Smells
    Alternative Classes
    w/ Different Interfaces
    Comments
    Data Class
    Data Clumps
    Divergent Change
    Duplicated Code
    Feature Envy
    Parallel Inheritance
    Hierarchies
    Primitive Obsession
    Refused Bequest
    Shotgun Surgery
    Speculative Generality
    Switch Statements
    Temporary Field
    Inappropriate Intimacy
    Incomplete Library Client
    Large Class
    Long Method
    Long Parameter List
    Message Chains
    Middle Man
    Lazy Class

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  7. @sandimetz May 2016

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  8. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Comments
    Data Class
    Data Clumps
    Divergent Change
    Duplicated Code
    Feature Envy
    Parallel Inheritance
    Hierarchies
    Primitive Obsession
    Refused Bequest
    Shotgun Surgery
    Speculative Generality
    Switch Statements
    Temporary Field
    Classic Smells
    Inappropriate Intimacy
    Incomplete Library Client
    Large Class
    Long Method
    Long Parameter List
    Message Chains
    Middle Man
    Lazy Class

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  9. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Comments
    Data Class
    Data Clumps
    Divergent Change
    Duplicated Code
    Feature Envy
    Parallel Inheritance
    Hierarchies
    Primitive Obsession
    Refused Bequest
    Shotgun Surgery
    Speculative Generality
    Switch Statements
    Temporary Field
    Classic Smells
    Inappropriate Intimacy
    Incomplete Library Client
    Long Method
    Long Parameter List
    Message Chains
    Middle Man
    Lazy Class
    Large Class

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  10. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Data Class
    Data Clumps
    Divergent Change
    Duplicated Code
    Feature Envy
    Parallel Inheritance
    Hierarchies
    Primitive Obsession
    Refused Bequest
    Shotgun Surgery
    Speculative Generality
    Switch Statements
    Temporary Field
    Classic Smells
    Inappropriate Intimacy
    Long Method
    Long Parameter List
    Message Chains
    Middle Man
    Lazy Class
    Large Class

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  11. @sandimetz May 2016
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class

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  12. @sandimetz May 2016
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class

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  13. @sandimetz May 2016
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class

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  14. @sandimetz May 2016
    Bloaters
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class

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  15. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class
    Bloaters

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  16. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field

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  17. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field

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  18. @sandimetz May 2016
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field

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  19. @sandimetz May 2016
    Tool Abusers
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field

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  20. @sandimetz May 2016
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class
    Bloaters
    Abusers
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery

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  21. @sandimetz May 2016
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery

    View Slide

  22. @sandimetz May 2016
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery

    View Slide

  23. @sandimetz May 2016
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery

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  24. @sandimetz May 2016
    Change Preventers
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery

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  25. @sandimetz May 2016
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class
    Bloaters
    Abusers
    Preventers

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  26. @sandimetz May 2016
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class

    View Slide

  27. @sandimetz May 2016
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class

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  28. @sandimetz May 2016
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class

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  29. @sandimetz May 2016
    Dispensables Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class

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  30. @sandimetz May 2016
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class
    Bloaters
    Abusers
    Preventers
    Dispensables

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  31. @sandimetz May 2016
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man

    View Slide

  32. @sandimetz May 2016
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man

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  33. @sandimetz May 2016
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man

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  34. @sandimetz May 2016
    Couplers
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man

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  35. @sandimetz May 2016
    Feature Envy
    Inappropriate Intimacy
    Message Chains
    Middle Man
    Data Class
    Duplicated Code
    Speculative Generality
    Lazy Class
    Divergent Change
    Parallel Inheritance
    Hierarchies
    Shotgun Surgery
    Alternative Classes
    w/ Different Interfaces
    Refused Bequest
    Switch Statements
    Temporary Field
    Data Clumps
    Primitive Obsession
    Long Method
    Long Parameter List
    Large Class
    Bloaters
    Abusers
    Preventers
    Dispensables
    Couplers

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  36. @sandimetz May 2016
    Refactoring

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  37. @sandimetz May 2016
    Refactoring Recipe

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  38. @sandimetz May 2016
    Fowler 149:
    Extract Class

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  39. @sandimetz May 2016
    Refactoring Recipe

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  40. @sandimetz May 2016
    Code Smell
    Curative Refactoring Recipe

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  41. @sandimetz May 2016
    http://www.industriallogic.com/wp-content/uploads/2005/09/smellstorefactorings.pdf

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  42. @sandimetz May 2016
    http://www.industriallogic.com/wp-content/uploads/2005/09/smellstorefactorings.pdf

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  43. @sandimetz May 2016

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  44. @sandimetz May 2016
    1

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  45. @sandimetz May 2016
    class Sale < Persistence
    end

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  46. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  47. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  48. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  49. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  50. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  51. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  52. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  53. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  54. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

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  55. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

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  56. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  57. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  58. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  59. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  60. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  61. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  62. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  63. @sandimetz May 2016
    class Sale < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  64. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

    View Slide

  65. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  66. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  67. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  68. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  69. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  70. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  71. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    Kaboom

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  72. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

    View Slide

  73. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  74. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  75. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  76. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  77. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  78. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  79. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  80. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  81. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  82. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  83. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Larry
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Curly
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Mo
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  84. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Larry
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Curly
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Mo
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Fee
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Fi
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Foe
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  85. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Larry
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Curly
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Mo
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Fee
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Fi
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Foe
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  86. @sandimetz May 2016

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  87. @sandimetz May 2016
    2
    Data Clump | Extract Class

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  88. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  89. @sandimetz May 2016
    class Sale < Persistence
    end
    class Expense < Persistence
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  90. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  91. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  92. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  93. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  94. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  95. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  96. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  97. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  98. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  99. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Foo
    def sales_total(params)
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  100. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  101. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  102. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end

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  103. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  104. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Bar
    def weekly_sales_total(params)
    start_date = (Date.parse(params[:starting]))
    end_date = start_date + 6
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

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  105. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Bar
    def weekly_sales_total(params)
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

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  106. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: (start_date..end_date)).sum("cost")
    end
    end

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  107. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  108. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  109. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  110. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Baz
    def expense_total(params)
    start_date = (Date.parse(params[:starting])) rescue Date.today
    end_date = (Date.parse(params[:ending])) rescue start_date
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  111. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Baz
    def expense_total(params)
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  112. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: (Date.parse(params[:starting]))..(Date.parse(params[:ending]))).sum("cost")
    end
    end

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  113. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  114. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  115. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  116. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  117. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end
    Data Clump | Extract Class

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  118. @sandimetz May 2016
    3
    Message Chain | Hide Delegate

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  119. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  120. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  121. @sandimetz May 2016
    Foo
    Sale.where(date: range).sum("cost")

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  122. @sandimetz May 2016
    Foo Sale
    Sale.where(date: range).sum("cost")

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  123. @sandimetz May 2016
    Foo Sale
    where
    Sale.where(date: range).sum("cost")

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  124. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    Sale.where(date: range).sum("cost")

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  125. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    Sale.where(date: range).sum("cost")

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  126. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    Sale.where(date: range).sum("cost")

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  127. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    Sale.where(date: range).sum("cost")

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  128. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  129. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  130. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  131. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    a list
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  132. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    a list
    a list
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  133. @sandimetz May 2016
    Foo Sale
    Persistence
    where
    where
    List
    sum
    a list
    a list
    Sale.where(date: range).sum("cost")
    ??? ??? ???

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  134. @sandimetz May 2016
    Foo

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  135. @sandimetz May 2016
    DateRange
    Foo

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  136. @sandimetz May 2016
    Sale
    #where
    DateRange
    Foo

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  137. @sandimetz May 2016
    Sale
    #where
    DateRange
    Foo
    Immediate Collaborators

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  138. @sandimetz May 2016
    List
    #sum
    Sale
    #where
    DateRange
    Foo

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  139. @sandimetz May 2016
    List
    #sum
    Sale
    #where
    DateRange
    Foo

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  140. @sandimetz May 2016
    List
    #sum
    Sale
    #where
    DateRange
    Foo
    Sale.where(date: range).sum("cost")

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  141. @sandimetz May 2016
    List
    #sum
    Sale
    #where
    DateRange
    Foo
    I know my collaborators collaborators

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  142. @sandimetz May 2016
    List
    #sum
    Sale
    #where
    DateRange
    Foo
    This is gonna hurt

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  143. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  144. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  145. @sandimetz May 2016
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  146. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  147. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  148. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  149. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.where(date: range).sum("cost")
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  150. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  151. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.where(date: range).sum("cost")
    end
    end

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  152. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end

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  153. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end

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  154. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end

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  155. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end

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  156. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  157. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.where(date: range).sum("cost")
    end
    end

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  158. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.total(within: range)
    end
    end

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  159. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.total(within: range)
    end
    end

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  160. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.total(within: range)
    end
    end

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  161. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.total(within: range)
    end
    end

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  162. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params)
    range = DateRange.new(starting: params[:starting]).week_range
    Sale.total(within: range)
    end
    end
    class Baz
    def expense_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Expense.total(within: range)
    end
    end
    Message Chain | Hide Delegate

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  163. @sandimetz May 2016
    4
    Sidebar: How Much Reality?

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  164. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end

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  165. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end

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  166. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end

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  167. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end

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  168. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

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  169. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

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  170. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  171. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end
    Check the query result

    View Slide

  172. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  173. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  174. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  175. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end
    Depend on Sale class?

    View Slide

  176. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  177. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  178. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end
    Depend on Totalizable role!

    View Slide

  179. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  180. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  181. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    Sale.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  182. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  183. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  184. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  185. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  186. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  187. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end
    Two players of the Totalizable role

    View Slide

  188. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  189. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  190. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  191. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    assert_equal 28, Foo.new.sales_total(starting: "2016-04-01", ending: "2016-04-07")
    end
    end

    View Slide

  192. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    assert_equal 28, Foo.new.sales_total(params)
    end
    end

    View Slide

  193. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 28, Foo.new.sales_total(params)
    end
    end

    View Slide

  194. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 28, Foo.new.sales_total(params)
    end
    end

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  195. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 28, Foo.new.sales_total(params, model)
    end
    end

    View Slide

  196. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 28, Foo.new.sales_total(params, model)
    end
    end

    View Slide

  197. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 47, Foo.new.sales_total(params, model)
    end
    end

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  198. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 47, Foo.new.sales_total(params, model)
    end
    end
    FAST

    View Slide

  199. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # Slow Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 47, Foo.new.sales_total(params, model)
    end
    end

    View Slide

  200. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    # FAST Test
    class TotalizableDouble
    def self.total(within:)
    47
    end
    end
    class FooTest < Minitest::Test
    def test_sales_total
    params = {:starting => "2016-04-01", :ending => "2016-04-07"}
    model = TotalizableDouble
    assert_equal 47, Foo.new.sales_total(params, model)
    end
    end

    View Slide

  201. @sandimetz May 2016
    5
    Duplicated Code | Pull Up Method

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  202. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  203. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  204. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  205. @sandimetz May 2016
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  206. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  207. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  208. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end

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  209. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    Speculative Generality

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  210. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    class Expense < Persistence
    def self.total(within:)
    where(date: within).sum("cost")
    end
    end
    Dependency Injection
    Is
    Awesome

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  211. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    end
    class Expense < Persistence
    end

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  212. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    extend Totalable
    end
    class Expense < Persistence
    extend Totalable
    end

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  213. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    extend Totalable
    end
    class Expense < Persistence
    extend Totalable
    end

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  214. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    extend Totalable
    end
    class Expense < Persistence
    extend Totalable
    end
    Duplicated Code | Pull Up Method

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  215. @sandimetz May 2016
    Code Smell
    Curative Refactoring Recipe

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  216. @sandimetz May 2016

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  217. @sandimetz May 2016
    class DateRange
    attr_reader :starting, :ending
    def initialize(starting:, ending: nil)
    @starting = Date.parse(starting) rescue Date.today
    @ending = Date.parse(ending) rescue @starting
    end
    def range
    starting..ending
    end
    def week_range
    starting..(starting + 6)
    end
    end

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  218. @sandimetz May 2016
    module Totalable
    def total(within:, date_field: :date, on: "cost")
    where({date_field => within}).sum(on)
    end
    end
    class Sale < Persistence
    extend Totalable
    end
    class Expense < Persistence
    extend Totalable
    end

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  219. @sandimetz May 2016
    class Foo
    def sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end
    class Bar
    def weekly_sales_total(params, model=Sale)
    range = DateRange.new(starting: params[:starting]).week_range
    model.total(within: range)
    end
    end
    class Baz
    def expense_total(params, model=Expense)
    range = DateRange.new(starting: params[:starting], ending: params[:ending]).range
    model.total(within: range)
    end
    end

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  220. @sandimetz May 2016
    Fist Pump

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  221. @sandimetz May 2016
    Fist Pump

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  222. @sandimetz May 2016

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  223. @sandimetz May 2016
    Reek

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  224. @sandimetz May 2016

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  225. @sandimetz May 2016

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  226. @sandimetz May 2016

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  227. @sandimetz May 2016

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  228. @sandimetz
    Thanks
    May 2016

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  229. @sandimetz
    References
    May 2016
    http://martinfowler.com/books/refactoring.html

    http://www.refactoringinruby.info/ Kevin Rutherford, William Wake

    Mäntylä, M. V. and Lassenius, C. "Subjective Evaluation of Software Evolvability Using Code Smells: An
    Empirical Study". Journal of Empirical Software Engineering, vol. 11, no. 3, 2006, pp. 395-431.
    https://github.com/troessner/reek

    https://blog.codeship.com/how-to-find-ruby-code-smells-with-reek

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  230. @sandimetz
    Credits
    May 2016
    Coffee on a Winter's morning, Stefan Lins, https://www.flickr.com/photos/mrlins/8533102693/
    Royal Australian Air Force in Australia during World War II, Argus Newspaper Collection of Photographs, State
    Library of Victoria, https://www.flickr.com/photos/statelibraryofvictoria_collections/16554906225/
    Chevy Crusher, Ruby Eng , https://www.flickr.com/photos/mac-ash/4105522760/
    Misuse Makes Mishaps, Jeremy Brooks , https://www.flickr.com/photos/jeremybrooks/2205135193,
    resistance is futile, Lora, https://www.flickr.com/photos/laroyo/6871150550/
    Well this is pointless, Janet McKnight, https://www.flickr.com/photos/janetmck/2613441853/
    Glue goo 3, Sam-Cat, https://www.flickr.com/photos/samcatchesides/3326878644/
    poses of victory, Daniel Novta, https://www.flickr.com/photos/vanf/7304661962/
    Odorous smells!, auddess, https://www.flickr.com/photos/auddess/4744679975
    EXPLORE] Smell the Flowers, Christine und David Schmitt, https://www.flickr.com/photos/cheesy42/8624536219/
    PIZZA, Tobi Gaulke. https://www.flickr.com/photos/gato-gato-gato/15958062095/
    Ain't Life Grand, Anne Worner, https://www.flickr.com/photos/wefi_official/9305161946/

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  231. @sandimetz
    http://poodr.com
    May 2016

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  232. @sandimetz
    http://99bottlesbook.com
    May 2016

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  233. @sandimetz
    Sandi Metz
    @sandimetz
    http://sandimetz.com
    May 2016

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  234. @sandimetz
    Questions?
    May 2016

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  235. @sandimetz
    Sandi Metz
    @sandimetz
    http://sandimetz.com
    May 2016

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