From: Jim Weirich <jim@...>
Date: 2008-09-11T14:24:15+09:00
Subject: Re: Local variable in loop affects callcc

Sean O'halpin wrote:
> On Tue, Sep 9, 2008 at 5:48 PM, Pinku Surana <suranap@gmail.com> wrote:
>>
>> I'm using "ruby 1.8.6 (2007-09-24 patchlevel 111) [i486-linux]" built
>>    ret.call(2)
>>
>>
>>
> 
> Like David, I haven't fully unravelled this myself, however it appears
> to be a scoping issue. If you replace the
> 
>   for i in 0..2
> 
> with
> 
>   (0..2).each do |i|
> 
> you get the correct result in both cases.
> 
> Regards,
> Sean


Ko1 once showed me a trick with continuations and local variables. 
Local variables in the Ruby stack are not restored to their values when 
the continuation is reentered.  However, variables stored in the C-stack 
(by the implementation) are restored (since the C-stack is copied and 
restored when calling a continuation).   (NOTE: I may have this 
backwards, it is too late at night).

I suspect this may be the essential difference between for and each.

-- Jim Weirich
-- 
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