Modules and Mixins

A module can be included in a class to share reusable methods.
mixin A mixin is a module included into a class so its methods act like instance methods.
                            tracking_id
                            tracking_id = 100 (default)tracking_id = 205tracking_id = 310
                        

                            modules_mixins.rb
                        
Replay: real traced execution (multi-file project)

                            module Trackable
  def tracking_label
    "tracking #{tracking_id}"
  end
end

class Shipment
  include Trackable

  def initialize(tracking_id)
    @tracking_id = tracking_id
  end

  def tracking_id
    @tracking_id
  end
end

tracking_id = 100
shipment = Shipment.new(tracking_id)

puts shipment.tracking_label
module Trackable
  def tracking_label
    "tracking #{tracking_id}"
  end
end

class Shipment
  include Trackable

  def initialize(tracking_id)
    @tracking_id = tracking_id
  end

  def tracking_id
    @tracking_id
  end
end

tracking_id = 205
shipment = Shipment.new(tracking_id)

puts shipment.tracking_label
module Trackable
  def tracking_label
    "tracking #{tracking_id}"
  end
end

class Shipment
  include Trackable

  def initialize(tracking_id)
    @tracking_id = tracking_id
  end

  def tracking_id
    @tracking_id
  end
end

tracking_id = 310
shipment = Shipment.new(tracking_id)

puts shipment.tracking_label

                        
1tracking_id ← 100⋯7class Shipment8  include TrackableTrackable910  def initialize(tracking_id)11    @tracking_id = tracking_id12  end1314  def tracking_id15    @tracking_id16  end17end1819tracking_id→ 100 = 100  #@tracking_id=205, 31020shipment = Shipment.new(tracking_id100)⋯
2@tracking_id ← 100⋯10def initialize(tracking_id100)11  @tracking_id→ 100 = tracking_id10012end⋯
3shipment ← ⟨Shipment A @tracking_id=100⟩⋯19tracking_id = 100  #@tracking_id=205, 31020shipment→ ⟨Shipment A @tracking_id=100⟩ = Shipment.new(tracking_id100)2122puts shipment.tracking_labeltracking 100⋯
4def tracking_id⋯14def tracking_id15  @tracking_id10016end⋯
5puts shipment.tracking_label⋯22puts shipment.tracking_labeltracking 100⋯outputtracking 100
1tracking_id ← 205⋯7class Shipment8  include TrackableTrackable910  def initialize(tracking_id)11    @tracking_id = tracking_id12  end1314  def tracking_id15    @tracking_id16  end17end1819tracking_id→ 205 = 20520shipment = Shipment.new(tracking_id205)⋯
2@tracking_id ← 205⋯10def initialize(tracking_id205)11  @tracking_id→ 205 = tracking_id20512end⋯
3shipment ← ⟨Shipment A @tracking_id=205⟩⋯19tracking_id = 20520shipment→ ⟨Shipment A @tracking_id=205⟩ = Shipment.new(tracking_id205)2122puts shipment.tracking_labeltracking 205⋯
4def tracking_id⋯14def tracking_id15  @tracking_id20516end⋯
5puts shipment.tracking_label⋯22puts shipment.tracking_labeltracking 205⋯outputtracking 205
1tracking_id ← 310⋯7class Shipment8  include TrackableTrackable910  def initialize(tracking_id)11    @tracking_id = tracking_id12  end1314  def tracking_id15    @tracking_id16  end17end1819tracking_id→ 310 = 31020shipment = Shipment.new(tracking_id310)⋯
2@tracking_id ← 310⋯10def initialize(tracking_id310)11  @tracking_id→ 310 = tracking_id31012end⋯
3shipment ← ⟨Shipment A @tracking_id=310⟩⋯19tracking_id = 31020shipment→ ⟨Shipment A @tracking_id=310⟩ = Shipment.new(tracking_id310)2122puts shipment.tracking_labeltracking 310⋯
4def tracking_id⋯14def tracking_id15  @tracking_id31016end⋯
5puts shipment.tracking_label⋯22puts shipment.tracking_labeltracking 310⋯outputtracking 310