From: Sean O'Halpin <sean.ohalpin@...>
Date: 2009-04-20T06:53:39+09:00
Subject: Re: ruby1.9 and the retry keyword

On Sun, Apr 19, 2009 at 7:17 PM, Yoann Guillot <john-rubytalk@ofjj.net> wrote:
> On Mon, Apr 20, 2009 at 02:10:33AM +0900, James Gray wrote:
>> On Apr 19, 2009, at 12:01 PM, Christopher Dicely wrote:
>>
>>> That mimics the example (where the retry is unconditional), but
>>> clearly isn't a general solution;
>>
>> I'll be surprised if more complex examples can't be similarly converted
>> fairly easily.  That was kind of my point.  I meant the code to say, take
>> a step back and think what is this trying to do?
>>
>
> My code walks an array, and may change the current element, which is allowed
> without breaking the iteration.
>
> I have also a special case where i have to change a whole subsection of the
> array, this was the case where i used 'retry'
>
> eg
> ary.each { |e|
>        case e
>        when foo
>                ary[ary.index(e)] = foo(e)
>        when bar
>        when ...
>        when baz
>                ary[ary.index(e), 12] = [flublu]
>                retry
>        end
> }
>
> Sure, i could use map or many other ways, my code is quite ugly anyway.
> I was just surprised by the change of behavior.
>
> I don't see the point in removing capabilities from the language (restarting
> an iteration from within), but I can sure live with it.
>
> --
> Yoann
>
>

You could do this I guess:

ary = [:foo, :bar, :baz, :foo]

def foo(e)
  :bom
end

class Retry < StandardError
end

begin
  ary.each { |e|
    case e
    when :foo
      ary[ary.index(e)] = foo(e)
    when :bom
      ary[ary.index(e)] = :foobom # to show retry
    when :baz
      ary[ary.index(e), 12] = [:flublu]
      raise Retry
    end
  }
rescue Retry
  retry
end
p ary
__END__
[:foobom, :bar, :flublu]

but as you point out, this is not restarting the iteration from within.

Regards,
Sean