From: Gavin Sinclair <gsinclair@...>
Date: 2003-10-22T23:47:22+09:00
Subject: Re: [Q] Array not Comparable?

On Thursday, October 23, 2003, 12:40:50 AM, ts wrote:

>>>>>> "G" == Gavin Sinclair <gsinclair@soyabean.com.au> writes:

G>> A. "Arrays are not comparable in general."
G>> B. Array implements <=>.

G>> Seems like a contradiction to me.

>  Well, if you look at the classes which include Comparable you'll see that
>  #<=> return (-1, 0, 1) when the 2 objects are in the same class (this is
>  simplified, see for example String#<=>) 

>  This is not the case for Array

> svg% ruby -e 'p ([1, "a"] <=> [1, 2])'
> nil
> svg% 

>  You have 2 arrays, but ruby can't compare these objects


So:

  class Array
    include Comparable
  end

  [1, 3] > [1, 2]               # true
  [1, "a"] > [1, 2]             # ArgumentError: comparison of Array with Array failed

  
Seems logical to me.

Gavin