date time comparison

Hi there

in RoR i can convert a Time into a Date object

t = Time.new
=> Thu Jun 14 14:00:46 BST 2007
d = Date.new(2007,06,03)
#<Date: 4908509/2,0,2299161>
t.to_date
=> #<Date: 4908531/2,0,2299161>
d.to_time
=> Sun Jun 03 00:00:00 BST 2007

But I can not compare Date and Time object

t > d

ArgumentError: comparison of Time with Date failed

Now, am I shooting myself in the foot if I do something like

class Date
  alias oldcmp <=>
  def <=>(other)
    if other.respond_to? :to_date
      oldcmp(other.to_date)
    else
      oldcmp(other)
    end
  end
end

class Time
  alias oldcmp <=>
  def <=>(other)
    if other.respond_to? :to_time
      oldcmp(other.to_time)
    else
      oldcmp(other)
    end
  end
end

To allow comparison among Date and Time objects?

Thanks

Paolo