DSL Example in Ruby

Cookbook

recipe :pasta do
    add 1.liter, of: :water, in: :pot
    turn_on :fire
    wait_until :pot, :boiling?

    add 1.gram, of: :salt, in: :pot
    wait 1.minute

    add 150.grams, of: :pasta, in: :pot

    cook for: 3.minutes

    remove :water, from: :pot

    eat :pasta
end

dsl_parser.rb

class CookbookDSL
    def initialize(file_name)
        @recipes = []
        instance_eval(File.read(file_name), file_name)
    end

    def recipe(name, &block)
        @recipes << Recipe.new(name, &block)
    end
end

class Ingredient
    def initialize(name, options = {})
        @name = name
        @options = options
    end
end

class Action
    def initialize(action, options = {})
        @action = action
        @options = options
    end
end

class Recipe
    def initialize(&block)
        @steps = []
        instance_eval(&block)
    end

    def add(amount, options)
        @steps << Ingredient.new(amount, options)
    end

    def turn_on(device)
        @steps << Action.new(:turn_on, device)
    end

    def wait(time)
        @steps << Action.new(:wait, time)
    end

    def wait_until(device, condition)
        @steps << Action.new(:wait_until, device, condition)
    end

    def remove(device, options)
        @steps << Action.new(:remove, device, options)
    end

    def cook(options)
        @steps << Action.new(:cook, options)
    end

    def eat(item)
        @steps << Action.new(:eat, item)
    end
end

class Quantity
    def initialize(value, unit_of_measure)
        @value = value
        @unit_of_measure = unit_of_measure
    end
end

class Integer
    def grams
        Quantity.new(self, :grams)
    end

    def gram
        Quantity.new(self, :grams)
    end

    def liter
        Quantity.new(self, :liters)
    end

    def liters
        Quantity.new(self, :liters)
    end

    def kilograms
        Quantity.new(self * 1000, :grams)
    end
end

usage.rb

CookbookDSL.new('./Cookbook')