From: Dave Thomas <Dave@...>
Date: 2001-12-05T00:05:00+09:00
Subject: [ruby-talk:27451] Re: Checking objects in a drb net

Massimiliano Mirra <list@chromatic-harp.com> writes:

> I'm trying to make my app (an ICQ LAN-only clone) a bit real-world
> compliant, and must handle the case where a client is shutted down
> without first calling its logout method first (because of a kill
> signal, of a crash, or whatever).  In other words the server has to
> handle refs to remote objects that stopped existing without telling
> it.

You could rescue the exception and remove the client. Here's a trivial
module based on the standard Observable module that does just that:

     module DRbObservable

       def add_observer(observer)
         @observer_peers ||= []
         unless observer.respond_to? :update
           raise NameError, "observer needs to respond to `update'" 
         end
         @observer_peers.push observer
       end

       def delete_observer(observer)
         @observer_peers.delete observer if defined? @observer_peers
       end

       def notify_observers(*arg)
         return unless defined? @observer_peers
         for i in @observer_peers.dup
           begin
             i.update(*arg)
           rescue
             delete_observer(i)
           end
         end
       end

     end


Regards


Dave