From: Nathan Witmer <nwitmer@...>
Date: 2006-11-11T10:11:41+09:00
Subject: Re: Beginner question: testing for either condition?

It's a little unclear, but it sounds like you're looking for an
exclusive or. Looks like the bitwise XOR operator works on
expressions, not just bits:

false ^ false # => false
false ^ true  # => true
true ^ false  # => true
true ^ true   # => false
(1==1) ^ (1==2) # => true

So you should be able to do:

if (@unit.custodian_id == session[:person_id]) ^
(session[:person_role] == 'admin')