From: Dossy <dossy@...>
Date: 2002-08-29T09:28:40+09:00
Subject: Re: CompareByValue

On 2002.08.27, Ryan King <rking@panoptic.com> wrote:
> 
> I added another test, which makes this implementation fail, too.

Terrific!  I updated the code that makes the new test pass.

> The implementation could be hacked so that this passes.  However,
> I wrote it as a simple case to represent an arbitrarily recursive
> structure.
> 
> The recursion is what makes this problem a "Challenge" rather
> than a "Trivial Chunk of Code". =)

I don't think my solution to make the test pass is a "hack" that
just makes the test pass, but the whole class of tests involving
recursion, to pass.

  http://www.rubygarden.org/ruby?DossysCompareByValue

Here's the code for folks to review:

 module CompareByValue
   def CompareByValue.compare(a, b)
     return true if a.equal? b
     return false unless a.instance_of? b.type
     return false unless a.instance_variables == b.instance_variables
     a.instance_variables.each { |name|
       next if a.equal? a.instance_eval(name)
       next if a.equal? b.instance_eval(name)
       return false unless CompareByValue.compare(a.instance_eval(name),
         b.instance_eval(name))
     }
     true
   end
   def ==(other)
     return CompareByValue.compare(self, other)
   end
 end

-- Dossy

-- 
Dossy Shiobara                       mail: dossy@panoptic.com 
Panoptic Computer Network             web: http://www.panoptic.com/ 
  "He realized the fastest way to change is to laugh at your own
    folly -- then you can let go and quickly move on." (p. 70)