A time subclass represents only the time of a day.

TimeOfDay.rb

class TimeOfDay < Time
    def <=>(another_time)
        self_time_of_day = Time.local(Time.now.year, Time.now.month, Time.now.day, 
                                    self.hour, self.min, self.sec )
        another_time_of_day = Time.local(Time.now.year, Time.now.month, Time.now.day, 
                                    another_time.hour, another_time.min, another_time.sec)

        self_time_of_day <=> another_time_of_day
    end 
end