gistfile1.txt

# ./bin/puppet apply -e '$foo = undef notice(inline_template("<%= foo.inspect %>"))'
/Users/ken/Development/puppet/lib/puppet/defaults.rb:127: warning: Insecure world writable dir /usr/local/share in PATH, mode 040777
Notice: Scope(Class[main]): :undef
Notice: Finished catalog run in 0.12 seconds

cat ~/.puppet/modules/foo/lib/puppet/parser/functions/foo.rb

module Puppet::Parser::Functions
newfunction(:foo, :type => :statement) do |arguments|
puts arguments[0].inspect
end
end

~/Development/puppet/bin/puppet apply -e 'foo(undef)'

""