dsl.rb

module Recipe
  Version = Class.new(Gem::Version)

  class Definition
   attr_reader :options
    def initialize(recipe_name, options = {})
      @options = options
      recipe recipe_name
    end

    def errors
      @errors ||= {}
    end

    def recipe(name = nil)
      return @recipe if name.nil?
      @recipe = name
    end

    def version(version_number = nil)
      return @version if version_number.nil?
      @version = Version.new(version_number)
    rescue => ex
      add_error(:version, :format, ex.message)
    end

    private

    def add_error(field, type, message)
      errors[field] ||= {}
      errors[field][type] ||= []
      errors[field][type] << message
    end
  end

  def self.define(name = nil, options = {}, &block)
    recipe = Definition.new(name, options)
    recipe.instance_exec(&block) if block_given?
    loaded_definitions << recipe
    recipe
  end

  def self.loaded_definitions
    @loaded_definitions ||= []
  end
end

recipe = Recipe.define "moms spaghetti" do
  version "1.3.4"
  ingredients do
    ingredient "spaghetti" do
      grams 100
    end
  end
end