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Ruby Modules

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Extend and Include

4:14 with Jason Seifer

In this video, we learn a little trick with extending and including something at the same time.

Code Samples

module Inventoryable

  def self.included(klass)
    klass.extend(ClassMethods)
  end

  module ClassMethods
    def create(attributes)
      object = new(attributes)
      instances.push(object)
      return object
    end

    def instances
      @instances ||= []
    end
  end

  def stock_count
    @stock_count ||= 0
  end

  def stock_count=(number)
    @stock_count = number
  end

  def in_stock?
    stock_count > 0
  end

end

class Shirt
  include Inventoryable
  attr_accessor :attributes

  def initialize(attributes)
    @attributes = attributes
  end
end

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    Now what we're gonna do is take the same pattern that we used in the tracking 0:00
    module to do this create and return instances. 0:02
    So, we're gonna do this in a tricky little way. 0:08
    We're gonna do it inside of another module, inside of Inventoryable. 0:11
    We're gonna call this ClassMethods 0:15
    because these are going to go on the class of what we want inventoried. 0:19
    So let's go ahead and write our create method. 0:25

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