RubyConf-NG Design Patterns

rubyconf-ng-abstract-factory.rb

# The Abstract Factory
class Waiter
  def initialize meal_order
    @meal_order = meal_order
  end

  def serve!
    @meal_order.utensil
    @meal_order.delicacy
  end
end

# Orders
module OrderInterface
  def utensil
    raise 'Not implemented.'
  end

  def delicacy
    raise 'Not implemented.'
  end
end

# For completeness, we bind the orders to an OrderInterface

# A Factory
class JollofMealOrder
  include OrderInterface
  def utensil
    puts 'Take one spoon'
  end

  def delicacy
    puts 'Jollof for the masses'
  end
end

# A Factory
class ClassyJollofMealOrder
  include OrderInterface
  def utensil
    puts 'Take a knife, and a fork'
  end

  def delicacy
    puts 'Jollof for the masses'
  end
end

# A Factory
class AmalaMealOrder
  include OrderInterface
  def utensil
    puts 'Chop with ya hand o jare!'
  end

  def delicacy
    puts 'Beta Amala and Ewedu'
  end
end

# First Customer waltzes in with an order
first_customer_order = ClassyJollofMealOrder.new

# ...places the order with a waiter
waiter1 = Waiter.new first_customer_order

# Waiter serves the order
waiter1.serve!

# Another customer places an order
another_customer_order = AmalaMealOrder.new

# ...places the order with a waiter
waiter2 = Waiter.new another_customer_order

# Waiter serves the order
waiter2.serve!

rubyconf-ng-decorator.rb

# This is the shoe as sold by the manufacturer
class Shoe
  def cost
    manufacturing_cost
  end

  def manufacturing_cost
    40
  end
end

# Same shoe in a Lekki Store
class LekkiShoe < Shoe
  def cost
    super * 1.23
  end
end

# Same shoe at Yaba Market
class YabaShoe < Shoe
  def cost
    super * 0.73
  end
end

# Same shoe in Dubai
class DubaiShoe < Shoe
  def cost
    super * 8
  end
end

# any shoe in a nice KPakagee box
module KPakagee
  def cost
    super * 2.15
  end
end

yaba_shoe = YabaShoe.new
puts yaba_shoe.cost
dubai_shoe = DubaiShoe.new
puts dubai_shoe.cost
dubai_shoe.extend(KPakagee) # dynamic way to add decorators without using inheritance
puts dubai_shoe.cost