From: MonkeeSage <MonkeeSage@...>
Date: 2007-12-05T19:30:00+09:00
Subject: Re: I think this is cool, ruby iterators and continuations

On Dec 4, 1:18 pm, "wbsurf...@yahoo.com" <wbsurf...@gmail.com> wrote:
> =begin
>
>  This might be old hat to some, but I just figured out how to make an
> iterator so that if I get some kind of failure, it will return the
> element and try again on the same iteration. The code below is just a
> simulation, but now that I have this example working, I know how to
> code what I really want. This feature of ruby really impresses me
> alot !
>
> =end
>
> #####################################
>
> $fail = true
>
> $cont = nil
>
> def proc_tab
>   statement = ["first statement", "second statement",
>   "third statement"]
>
>     statement.each_with_index do |stat,idx|
>       if $cont
>         cont = $cont
>         $cont = nil
>         cont.call
>       end
> # simulate a failure on index 1
>       callcc {|cont| $cont = cont } if idx == 1 and $fail
>       $fail = false if $cont
>       yield stat
>     end
> end
>
> ["searchCIO","searchCRM"].each do |site|
>   (1..5).each do |art|
>     $fail = true
>     puts site + "->" + art.to_s
>     proc_tab do |stat|
>       puts "stat:"  + stat
>     end
>   end
> end

I'm not sure how useful it is to signal failure in the block of
proc_tab (seems like that would be something to go in the method body
instead; i.e., check the value and fix it/skip it/whatever before you
yield it to the block). But in any case, I don't think you actually
need continuations for this...

$fail = false

class IterError < Exception; end

def proc_tab
  statement = ["first statement",
               "second statement",
               "third statement"]
  statement.each_index { | idx |
    begin
      # simulate a failure on index 1
      yield statement[idx]
      raise IterError if idx == 1 and $fail
    rescue IterError
      $fail = false
      retry
    end
  }
end

["searchCIO", "searchCRM"].each { | site |
  (1..5).each { | art |
    $fail = true
    puts site + "->" + art.to_s
    proc_tab { | stat |
      puts "stat:"  + stat
    }
  }
}

Regards,
Jordan