From: Ara.T.Howard@...
Date: 2004-11-11T08:13:31+09:00
Subject: Re: array.each restart when array is changed

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On Wed, 10 Nov 2004, Kevin [ISO-8859-15] B=F6rgens wrote:

> Hi!
>
>
> How to restart a "each" iteration when the iterated array is changed? I d=
o
> it like this
>
> changed=3Dfalse
> while (changed)
> changed=3Dfalse
> array.each {|e|
>  if (today_is_christmas)
>    array=3Darray+=3D["Hello santa claus"]
>    changed=3Dtrue
>  end
> }
>
> Is there a more elegant way to do this?
>
>
> Second question:
> why is this not allowed
>
> #show me the first n letters of the alphabet
> ('a'...'a'+gets.to_i).each{|e| puts e }
>
> How to do it the right way?
>
> Thanks in advance,
> Kevin

maybe:

   harp:~ > cat a.rb
   bits =3D [0, 1, 0, 1]
   n =3D 0

   begin
     bits.each_with_index do |bit, pos|
       n |=3D (bit << pos)
       bits << 0 << 1 and raise 'changed' if bits.size =3D=3D 4 and pos =3D=
=3D 3
     end
   rescue =3D> e
     retry
   end

   p n
   printf "%b\n", n


   harp:~ > ruby a.rb
   42
   101010

i don't know if changing an array while iterating is safe though - i'll def=
er
to someone else on that note.

cheers.

-a
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| EMAIL   :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
| PHONE   :: 303.497.6469
| When you do something, you should burn yourself completely, like a good
| bonfire, leaving no trace of yourself.  --Shunryu Suzuki
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