From: "Aaron D. Gifford" <astounding@...>
Date: 2011-03-26T21:37:24+09:00
Subject: Re: shortcut for add unless nil ?

I was heard to muse:
> An alternative for the original poster's ENV variables potentially
> containing colon-separated paths:
>
>  %w{FOO BAR BAZ}.map{|x| ENV[x].to_s}.join(':').split(/:+/)
>
> The .to_s should handle nil just fine. Concatenate all the strings,
> then do the split.

Append a .uniq to that as desired.  Or do:
 %w{FOO BAR BAZ}.map{|x| ENV[x].to_s.split(/:+/) || []}.flatten.uniq

Aaron out.