From: ara.t.howard@...
Date: 2006-08-09T23:13:19+09:00
Subject: Re: why doesn't Array include Comparable

On Wed, 9 Aug 2006, Hal Fulton wrote:

> Offhand I would guess it's because arrays can
> hold arbitrary objects.
>
> If one array held four different classes of
> objects, and another held yet another four
> classes of objects, that's potentially sixteen
> spaceship operators that would need to be
> defined for this to make sense. And most of
> those would not make sense anyway.

i don't understand - it's up to to the objects inside the container to
impliment the right methods and array already knows how to handle it:


   harp:~ > cat a.rb
   a = 0, 'foo', 42
   b = 1, 'bar', 42.0

   p a < b rescue puts "can't do that"

   class Array; include Comparable; end

   p a < b

   p a.sort_by{ rand } < b.sort_by{ rand }


   harp:~ > ruby a.rb
   can't do that
   true
   a.rb:9:in `<': comparison of Array with Array failed (ArgumentError)
           from a.rb:9


if you're collections impliment <=> correctly then Array does the right thing -
looping over each of them.

-a
-- 
to foster inner awareness, introspection, and reasoning is more efficient than
meditation and prayer.
- h.h. the 14th dali lama