From: Ryan Leavengood <leavengood@...>
Date: 2007-05-03T23:25:38+09:00
Subject: Re: [SUMMARY] Checking Credit Cards (#122)

On 5/3/07, Rick DeNatale <rick.denatale@gmail.com> wrote:
>
> After seeing the neat use of each_slice instead of each_with_index
>
> def luhn(string)
>   string.scan(/./).reverse.enum_for(:each_slice, 2).inject(0) do |sum, (d1, d2)|
>     sum += d1.to_i + (d2||'0').tr('0123456789', '0246813579').to_i
>   end  % 10 == 0
> end
>
> No need to define any extra Enumerator methods.

Nice, I like it. When I first thought about using
enum_for(:each_slice, 2) I was surprised that it even worked.
Enumerator is a powerful library.

It seems like I learn something new every time I do one of these
quizzes, either from making my own solution or reading someone else's.

Ryan