# from http://liquiddevelopment.blogspot.com/2006/04/way-of-meta-part-iv-hijacking-local.html

def report recipe, ingredients
    puts "to make #{recipe} you should buy:"
    ingredients.each_pair do 
        |ingredient,description| 
        puts " * #{Array(description).join ' '} #{ingredient}" 
    end
    puts 
end

def shopping_list recipe
    shopping_binding = yield
    ingredients = {}
    eval("local_variables" , shopping_binding). 
      each do |var|
        ingredients[var] = eval "#{var}" , shopping_binding 
      end

    report recipe, ingredients    
end

alias the binding

shopping_list "english breakfast" do
    tomatoes = 2, :green
    sausages = 3
    eggs = 2, :big
    bacon = 4
the end                 # returns binding

shopping_list "banana milkshake" do
    milk = 1
    bananas = 2    
the end