I was intrigued by the post that _why put up a few days/weeks ago about using case/when for testing arrays [1]. I thought I'd give it a try but I can't make it work. What am I doing wrong? irb(main):001:0> r1 = (0..12).to_a => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] irb(main):002:0> r2 = (20..32).to_a => [20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32] irb(main):003:0> def foo range irb(main):004:1> case range irb(main):005:2> when *r1 irb(main):006:2> puts "#{range} in r1" irb(main):007:2> when *r2 irb(main):008:2> puts "#{range} in r2" irb(main):009:2> else irb(main):010:2* puts "#{range} NOT in any range" irb(main):011:2> end irb(main):012:1> end => nil irb(main):013:0> foo 3 NameError: undefined local variable or method `r1' for main:Object from (irb):5:in `foo' from (irb):13 This is under OSX: ruby 1.8.4 (2005-12-24) [powerpc-darwin8.4.0] [1] http://redhanded.hobix.com/bits/wonderOfTheWhenBeFlat.html