From: Dossy <dossy@...>
Date: 2002-08-25T10:24:08+09:00
Subject: Re: CompareByValue

On 2002.08.25, Ryan King <rking@panoptic.com> wrote:
> I put a challenge up at:
>   http://www.rubygarden.org/ruby?CompareByValue

I don't think this is the /best/ solution, but it's one
that makes all ten tests pass:

    module CompareByValue
      def ==(other)
        # return true if self.id == other.id
        return false unless self.type == other.type
        return false unless self.instance_variables == other.instance_variables
        self.instance_variables.each { |name|
          next if self.id == self.instance_eval(name).id
          next if other.id == other.instance_eval(name).id
          next if self.id == other.instance_eval(name).id
          next if other.id == self.instance_eval(name).id
          return false unless self.instance_eval(name) ==
            other.instance_eval(name)
        }
        true
      end
    end

The commented-out line is not required to make the tests pass (that's
why it's commented out) but it's an optimization that might make the
comparison go faster.

> http://www.rubygarden.org/ruby?CompareByValueTests (which isn't
> even a thorough test suite, necessarily).

What kind or class of tests might be missing?

> I'm curious to see if this list can come up with something that's
> elegant and that works.

I'd rather see the list come up with a comprehensive list of tests that
would really give confidence that whatever code passes the test will
work.  ;-)

-- 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)