From: Alexandru Popescu <the.mindstorm.mailinglist@...>
Date: 2006-07-16T17:46:01+09:00
Subject: Re: salt = [Array.new(6){rand(256).chr}.join].pack("m").chomp

On 7/16/06, Mike Stok <mike@stok.ca> wrote:
>
> On 15-Jul-06, at 8:30 PM, Alexandru Popescu wrote:
>
> > To my understanding: creates
> > Array.new(6){rand(256).chr} => array of 6 random chars
> > array.join => string of 6 chars
> > [array.join] => array with 1 string of length 6
> > newarray.pack("m") => encode base64
> >
> > and the last chomp assures that the last generated char is not a
> > newline.
>
> Close - the pack('m') always pads its result with = if necessary (to
> get to a multiple of 4 characters for the encoded string) and adds a
> newline.  As we start with  6 characters, and base64 encoding turns
> three characters into four, we end up with an 8 character string plus
> a new line. The chomp deletes that newline.
>

I was quite close... thanks for details Mike :-).

./alex
--
.w( the_mindstorm )p.

> In irb:
>
> ratdog:~ mike$ irb --prompt simple
>  >> Array.new(6){rand(256).chr}
> => ["\332", "w", "\035", "!", "\237", "\030"]
>  >> ["\332", "w", "\035", "!", "\237", "\030"].join
> => "\332w\035!\237\030"
>  >> ["\332w\035!\237\030"].pack('m')
> => "2ncdIZ8Y\n"
>  >> "2ncdIZ8Y\n".chomp
> => "2ncdIZ8Y"
>
> Mike
>
> >
> > hth (even if I am not completely sure about it, and I would like to
> > hear from more experienced guys).
> >
> > ./alex
> > --
> > .w( the_mindstorm )p.
> >
> >
> >
> > On 7/16/06, Alexandre Hudelot <alexandre.hudelot@gmail.com> wrote:
> >> This is a line taken from the "authentification" recipe in the 'Rails
> >> Recipes' book.
> >> I can see that it generates a string of random characters but I am
> >> unsure of all that's going on here.
> >>
> >> The strings that are generated have 8 characters, how come when the
> >> array is initialized with the arg '6' ?
> >>
> >> What exactly is .join doing here?
> >>
> >> What does .pack("m") do?
> >>
> >> And why the .chomp? I thought that was a func to remove newline
> >> characters.
> >>
> >> Thanks in advance for the help.
> >>
> >> -Alex
> >>
> >> --
> >> Posted via http://www.ruby-forum.com/.
> >>
> >>
> >
> >
>
> --
>
> Mike Stok <mike@stok.ca>
> http://www.stok.ca/~mike/
>
> The "`Stok' disclaimers" apply.
>
>
>
>
>
>