From: "Brian F. Feldman" <green@...>
Date: 2001-01-08T04:17:34+09:00
Subject: [ruby-talk:8780] Re: No :<, :>, etc. methods for Array

matz@zetabits.com (Yukihiro Matsumoto) wrote:
> Hi,
> 
> In message "[ruby-talk:8774] No :<, :>, etc. methods for Array"
>     on 01/01/07, "Brian F. Feldman" <green@FreeBSD.org> writes:
> 
> |So, why not include Comparable in Array by default?  It shouldn't have any 
> |bad side-effects, and it makes sense that if Array implements :<=>, it 
> |should then include Comparable.
> 
> Because arrays are not always comparable.  `sort', `min', and `max' in
> Enumerable are the best compromise I could made.

So it's done to "discourage" people from doing it?  E.g. currently the best 
way to compare version numbers would be:

irb(main):003:0> ([1, 6, 2] <=> [1, 4, 3]) == 1
true

I also had a question if  Array specifically could have a Array#sum method; 
the behavior would be very simple and straightforward:

class Array
    def sum
        total = self[0]	# defaults to nil
	self[1..-1].each {|x| total += x}
	total
    end
end

It simplifies lots of things (especially mathematics) in Ruby to have it, 
and I believe it's generally useful enough that it should probably be 
standard.  What do you think?

-- 
 Brian Fundakowski Feldman           \  FreeBSD: The Power to Serve!  /
 green@FreeBSD.org                    `------------------------------'