template_method_example.rb

class Pie
  def make
    add_main_ingredient
    add_secondary_ingredients
    cook
    add_toppings
    let_cool
  end
  
  def add_ingredient(ingredient)
    @ingredients << ingredient
  end
  
  def oven_time
    25 # Default implementation for the oven time to make a generic pie.
  end
  
  def add_toppings
    # This is a hook method.
    # Since your concrete pie might or might not include toppings, this is empty for the subclasses to implement it if needed.
  end
  
  def cook
    put_in_oven
    wait_for_minutes(self.oven_time) # Asks for the oven time for the concrete pie.
    take_out_from_oven
  end
  
  def let_cool
    wait_for_minutes(30)
  end
end

class ApplePie < Pie
  def add_main_ingredient
    add_ingredient(:apples)
  end
  
  def add_secondary_ingredients
    add_ingredient(:sugar)
  end
  
  def add_toppings
     add_ingredient(:apple_slices) # This hook method is defined by the ApplePie, but not by the MeatPie since it's not needed.
  end
  
  def oven_time
    20 # We override the default implementation received by inheriting from Pie.
  end
end

class MeatPie < Pie
  def add_main_ingredient
    add_ingredient(:grounded_meat)
  end
  
  def add_secondary_ingredients
    add_ingredient(:salt)
    add_ingredient(:pepper)
  end
  
   def oven_time
    35 # We override the default implementation received by inheriting from Pie.
  end
end

MeatPie.make
ApplePie.make