# price.rb
 
class Price
   def initialize(val = 0); @val = val end
   attr_accessor :val
end
 
 
# decorate_price.rb
 
module Decoratable
   def decos; @decos ||= [] end
   def val; decos.inject(@val){ | acc, deco | deco[acc] } end
end
 
class Price; prepend Decoratable end
$Double = ->x{x*2}
$Wholesales = ->x,adv{x+adv}.curry
 
 
# decorate_price_test.rb
 
price = Price.new(120)
price.decos << $Double << $Wholesales[80] << $Double << $Wholesales[200]
p price.val

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