From: m_seki@...
Date: 2001-11-28T12:53:37+09:00
Subject: [ruby-talk:26734] Re: DRb and failing test, please give some insight...


> I couldn't find any documentation which does not presuppose prior
> knowledge of distributed objects and yet is something more than very
> basic, would love to hear that something is in the works.  (Yes, yes,
> I know, I would already be writing it if I were able to.)

I wrote a thin book.

  * http://www.ascii.co.jp/books/detail/4-7561/4-7561-3961-2.html
    (Distributed Object Programming by dRuby: (sorry, it is Japanese))


RWiki site: dRubyTut (Japanese, too)

  * http://www.jin.gr.jp/~nahi/RWiki/?cmd=view;name=dRubyTut 


Chad's tutorial (Yes, English)

  * http://www.chadfowler.com/ruby/drb.html


> > FYI, drb-1.3.3b's 'drb/eq' has hash, and eql? methods.
> 
> Pardon me... how does this relate to my Client/Server example?

Server class in your example, manage clients by using Array.
I'm worried about change Array to Hash .

 eg.
 |  class Server
 |    def initialize
 |      @users = {}
 |    end
 |    def register(user)
 |      @users[user] = Time.now
 |    end
 |    def online?(user)
 |      @users.include? user
 |    end
 |  end


The 'hash' method is called when compare hash keys.
drb-1.3.2's 'drb/eq' will misstake.

# test script:
require 'drb/drb'

def test_eq
  d1 = DRbObject.new(nil, 'druby://foo:12345')
  d2 = DRbObject.new(nil, 'druby://foo:12345')

  hash = {}
  hash[d1] = true

  p [(d1 == d2), hash.include?(d2)]
end
test_eq() # -> [false, false]

# drb-1.3.2 drb/eq.rb
module DRb
  class DRbObject
    def ==(other)
      return false unless DRbObject === other
      (@ref == other.__drbref) && (@uri == other.__drburi)
    end
  end
end
test_eq() # -> [true, false]


# drb-1.3.3b drb/eq.rb
module DRb
  class DRbObject
    def hash
      [@uri, @ref].hash
    end

    alias eql? ==
  end
end
test_eq() # -> [true, true]