From: Robert Dober <robert.dober@...>
Date: 2009-02-15T04:32:51+09:00
Subject: Re: while vs loop

On Sat, Feb 14, 2009 at 7:16 AM, Nobuyoshi Nakada <nobu@ruby-lang.org> wrote:
> Hi,
>
> At Sat, 14 Feb 2009 15:03:03 +0900,
> Vetrivel Vetrivel wrote in [ruby-talk:328175]:
>> what is the Difference between loop and while in ruby ?
>>
>> loop do
>> end
>
> loop is a kernel method which takes a block.  A block
> introduces new local variable scope.
>
>  loop do
>    a = 1
>    break
>  end
>  p a #=> causes NameError
>
>> while 1
>> end
>
> while doesn't.
>
>  while 1
>    a = 1
>    break
>  end
>  p a #=> 1
>
> --
> Nobu Nakada
>
furthermore loop do has an implicit rescue clause for a StopIteration exception
(I believe 1.8.7 and 1.9.1 only IIRC)

therefore

loop do
   some_enumerator.next
end
becomes a convenient idiom.

HTH
Robert



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