From: Peter Ertl <pertl@...>
Date: 2006-03-24T23:25:59+09:00
Subject: Re: iterator class not working

Thanks for all you help.

Finally, using two nested continuations works well...

Here's my working code ... I am very curious about 
optimization and alternatives from you guts. Afterall 
I found this issue a very exciting one!!

class Iterator

  def initialize(obj, method = :each)
    @obj = obj
    @method = method
  end

  def next
    raise "done" if @done
    @iteration.call if @iteration
    @iteration, @current = callcc do |loop|
      @obj.send(@method) do |item|
        callcc do |state|
          loop.call state, item
        end
      end
      nil
    end
    @current
  end

end

names = %w{peter paul mary gordy john jane elwood}

it = Iterator.new(names)
while item = it.next
  puts item
end

it = Iterator.new("Teststring", :each_byte)
while item = it.next
  puts item.chr
end


peter
paul
mary
gordy
john
jane
elwood
T
e
s
t
s
t
r
i
n
g


> --- Urspr�ngliche Nachricht ---
> Von: Ross Bamford <rossrt@roscopeco.co.uk>
> An: ruby-talk@ruby-lang.org (ruby-talk ML)
> Betreff: Re: iterator class not working
> Datum: Fri, 24 Mar 2006 23:10:05 +0900
> 
> Just a small fix:
> 
> On Fri, 2006-03-24 at 22:49 +0900, Ross Bamford wrote:
> >   def initialize(enum)
> >     @yield = lambda do
> >       enum.each do |item|
> > -       @yield = callcc { |cc|
>   +       callcc { |cc|
> >           @next.call cc, item
> >         }
> >       end
> >       raise "Exhausted"
> >     end
> >   end
> 
> Doesn't really hurt (as currently written) but it's unnecessary and
> could cause confusion.
> 
> -- 
> Ross Bamford - rosco@roscopeco.REMOVE.co.uk
> 
>