attr_accessor_with_history.rb

class Foo ; attr_accessor_with_history :bar ;  end
=> nil
f = Foo.new
=> #<Foo:0x127e678>
f.bar = 3
=> 3
f.bar = :wowzo
=> :wowzo
f.bar = 'boo!'
=> 'boo!'
f.history(:bar)
>> [3, :wowzo, 'boo!']