gistfile1.rb

class Foo
  def deadline_string=(deadline_string)
    self.deadline = (parse_string(deadline_string, Chronic) || parse_string(deadline_string, Time))
    @deadline_invalid = true unless self.deadline
  end

  private
  def parse_string(string, parser)
    begin
      parser.parse(string)
    rescue
    end
  end
end

That's good, but what about setting an error?