Ruby knows that:

  a = 4e5

... is a float, turning it into:

  400000.0

If I have a string "4e5", is there a way for me to leverage the parser's
ability to decipher this as a float? I know I can call:

  "4e5".to_f

... but for any string value, how can I do a proper conversion? I want a
routine like this:

  def convertString(value)
    # do magic stuff to convert value to proper Numeric,
    # assuming it's a valid Numeric representation
  end

I'd love to be able to call a Ruby routine to do this for me, same as the
parser does when reading in a script.

Chris