From: cilibrar@... (Rudi Cilibrasi)
Date: 2002-10-25T20:44:40+09:00
Subject: How come true, false don't support <=> (comparison) operator?

I am wondering if there is a good reason why Ruby does not by default
support, for instance,
true <=> false  (should be +1 or -1)
or even
false <=> false (should be 0)

I have been surprised at having to make my own versions of these
functions for use in an Array of boolean values.  Some people suggest
that I would be better off using integers and bitmasks, but the Array
has many methods that I need to use; for example, the <=> operator
as applied to booleans:
a = Array.new(10, true)
b = Array.new(10, false)
It would be convenient if I could compare the two bitstrings
lexicographically.
a <=> b
Another common thing I find myself needing is to sort these, like:
a.sort!

I have used the following code to make these operations work:
class TrueClass
  def to_i() 1 end
  def <=>(b)
    to_i <=> b.to_i
  end
end
class FalseClass
  def to_i() 0 end
  def <=>(b)
    to_i <=> b.to_i
  end
end

Would anything break if this were made a part of the standard package?
In thinking about possibilities for future versions of Ruby, perhaps
it would make sense to have TrueClass and FalseClass both derive
from a common base class, say, BooleanClass.

I would enjoy hearing your thoughts as a followup in this forum,

Rudi Cilibrasi