Ruby Light #4

eval_string.rb

class EvalString < String
  def eval(b)
    b.eval String.new(self)
  end
end

irb session

>> foo = 1
=> 1
>> bar = 2
=> 2
>> str = EvalString.new "foo+bar"
=> "foo+bar"
>> str
=> "foo+bar"
>> str.eval(binding)
=> 3