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require 'ostruct'

computer = OpenStruct.new(ram: '4GB')
computer.class          # => OpenStruct

computer.methods(false) # => []
computer[:ram]          # => "4GB"
computer.methods(false) # => []

computer.ram            # => "4GB"

mehdi-farsi

require 'ostruct'

computer = OpenStruct.new(ram: '4GB')
computer.class # => OpenStruct

computer.ram    # => "4GB"
computer[:ram]  # => "4GB"
computer['ram'] # => "4GB"

computer.screens = 2

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Struct.new('Address', :street, :city, :zip)

Struct::Address.superclass # => Struct

home = Struct::Address.new('Broadway', 'NYC', 10040)

home.class # => Struct::Address

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Address = Struct.new(:street, :city, :zip)

class Address
  def full_address
    "#{street} #{city} #{zip}"
  end
end

home = Address.new('Broadway', 'NYC', 10040)

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Address = Struct.new(:street, :city, :zip)

Address.class      # => Class
Address.superclass # => Struct

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home # => #<struct Address street="Broadway", city="NYC", zip=10040>

home.street = 'Opéra'
home[:city] = 'Paris'
home['zip'] = 75009

home # => #<struct Address street="Opéra", city="Paris", zip=75009>

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home.street # => "Broadway"
home[:city] # => "NYC"
home['zip'] # => 10040

home.not_exist    # => NoMethodError: undefined method `not_exist'
home[:not_exist]  # => NameError: no member 'not_exist' in struct
home['not_exist'] # => NameError: no member 'not_exist' in struct

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Address = Struct.new(:street, :city, :zip)
home = Address.new('Broadway', 'NYC', 10040)

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class User
  def self.inherited(user_type)
    puts "#{user_type} is a kind of user"
  end
end

class Tenant < User
end

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module Commentable
  def self.included(commentable_entity)
    puts "The #{commentable_entity} entity now accepts comments !"
  end
end

class MediumPost
  include Commentable
end