Cooking for Programmers: Spaghetti Carbonara

spaghetti_carbonara.rb

class Recipe
  attr_accessor :name, :servings, :ingredients, :instructions

  def initialize(name, servings=1, &block)
    self.name = name
    self.servings = servings
    self.ingredients = []
    self.instructions = []

    instance_eval &block
  end

  def ingredient(name, options = {})
    ingredient = {"name" => name, "amount" => options[:amount], "unit" => options[:unit]}

    ingredients << ingredient
  end

  def step(text, options = {})
    instruction = text
    instruction << " (#{options[:for]})" if options[:for]

    instructions << instruction
  end

  def to_s
    puts "\n#{name} recipe"
    output = ""
    output << "#{'=' * (name.size + 10)}\n\n"
    output << "Servings:\n  #{servings}\n\n"
    output << "Ingredients:\n"
    ingredients.each do |ingredient|
      output << "  #{ingredient['name']} (#{ingredient['amount'] * servings} #{ingredient['unit']})\n"
    end
    output << "\n"
    output << "Instructions:\n"
    instructions.each_with_index do |instructions, index|
      output << "  #{index + 1}) #{instructions}\n"
    end
    output
  end

  spaghetti_carbonara = Recipe.new("Spaghetti Carbonara", 2) do
    ingredient "Spaghetti",       :amount => 125, :unit => "g"
    ingredient "Unsalted butter", :amount => 2,   :unit => "tbsp"
    ingredient "Shallot",         :amount => 0.5, :unit => "pieces"
    ingredient "Garlic",          :amount => 1,   :unit => "cloves"
    ingredient "Mushrooms",       :amount => 75,  :unit => "g"
    ingredient "Pancetta",        :amount => 3,   :unit => "rashers"
    ingredient "Egg",             :amount => 1,   :unit => "egg"
    ingredient "Double cream",    :amount => 75,  :unit => "ml"
    ingredient "Parmesan",        :amount => 15,  :unit => "g"
    ingredient "Thyme",           :amount => 1,   :unit => "sprig"
    ingredient "Sea salt",        :amount => 1,   :unit => "pinch"
    ingredient "Black pepper",    :amount => 1,   :unit => "pinch"

    step "Prepare ingredients:\nFinely chop shallot and garlic, then cut the pancetta and mushrooms into thin strips. Grate your parmesan if it isn't already grated."

    step "Cook the pasta:\nBring a large pot of water to the boil, then add a pinch of salt but no oil. Once boiling, add the spaghetti and cook until al dente (about 1 minute under the recommended time on the packet). Proceed with the next steps while waiting."

    step "Prepare sauce:\nCrack eggs into a bowl and beat together with the cream, most of the parmesan, sea salt and ground black pepper. Set aside."

    step "Cook the components:\nAdd the pancetta to a very hot skillet, then throw in the chopped garlic and shallot together with the butter. Fry for a few minutes and then add the mushrooms. When golden, take off the heat."

    step "Combine:\nUsing a pair of tongs, place the cooked spaghetti into the skillet. Pour in the sauce from Step 3, and mix together. Add a spoonful or 2 of the water you cooked the pasta in to moisten the pasta. Throw in the rest of the parmesan, and add salt or pepper to taste. If the pasta gets dry, add more pasta water."

    step "Eat."

  end
  puts spaghetti_carbonara
end