We'll look at nil from many angles. Why do nils show up in your programs? What kinds of problems can they cause when they get out of control? How can we design our systems to fail loudly when unexpected nils exist and, more importantly, to avoid the introduction of nils entirely? This screencast uses Ruby, but the techniques apply in any language.

How and Why to Avoid Nil was published on 2011-02-24. It uses Rails 3.0.3, RSpec 2.4.0, Ruby 1.8.7, Vim 7.3, and Zsh 4.3.9.