From: Wyss Clemens <WYS@...>
Date: 2001-05-08T01:08:59+09:00
Subject: [ruby-talk:14786] Re: SimpleDelegator assymetry

> -----Urspr�ngliche Nachricht-----
> Von: Dave Thomas [mailto:Dave@PragmaticProgrammer.com]
> Gesendet am: Montag, 7. Mai 2001 17:39
> An: ruby-talk@ruby-lang.org; ruby-talk@netlab.co.jp
> Betreff: [ruby-talk:14784] Re: AW: Re: SimpleDelegator assymetry
> 
> Wyss Clemens <WYS@helbling.ch> writes:
> 
> > I have a somewhat "not so fast solution" ;-):
> 
> This will have a different behavior to the original delegate.rb. This
> code will not delegate a method that already exists in the delegating
> class, while the original will.

Robert, looks like this was meant by the comment in delegate.rb!

> Which is correct is yet to be determined :)
> 

But as Dave says, the question remains which of the behaviors is correct!
Below (not tested though) find a (possibly) more generic approach. 
No subclassing needed, as this is a "wrapper approach"!

class SimpleDelegatorBase
  def initialize(original_obj, delegatee = nil)
    @__originial_obj = original_obj
    @__delegatee = delegatee
  end

  def __setobj__(object)
    @__delegatee = object
  end

  def method_missing(method, *args)
    receivers().each { | receiver |
      safley_send(receiver, method, args)
    }
  end  

  def safely_send(receiver, method, *args)
    if receiver.respond_to?(method) then
      if args.size() == 0 then
        receiver.send(method)
      else
        receiver.send(method, args)
      end
    end
  end

  def receivers()
    [@__original_obj]
  end
end

class SimpleDelegatorOriginalPrecedence < SimpleDelegatorBase
  # special behavior here ("either-or")
  def method_missing(method, *args)
    if @__originial_obj.respond_to?(method) then
      safley_send(@__originial_obj, method, args)
    else
      safely_send(@__delegatee, method, args)
    end
  end
end

class SimpleDelegatorSubstitute < SimpleDelegatorBase
  def receivers()
    [@__delegatee]
  end  
end

class SimpleDelegatorPreCall < SimpleDelegatorBase
  def receivers()
    [@__delegatee, @__original_obj]
  end  
end

class SimpleDelegatorPostCall < SimpleDelegatorBase
  def receivers()
    [@__original_obj, @__delegatee]
  end  
end

;-)
Clemens