Hi, I face the following issue with a hash having an empty array as default value. I don't how to describe it in English, here is an illustrative code: hash = Hash.new Array.new hash[:a] = [1] hash[:b] << 2 puts hash[:b] # => returns [2] puts hash.keys # => returns [:a], not [:a, :b] ? hash[:b] is set to [2] but I don't understand why hash.keys does not include :b. Thanks!, Florent -- Posted via http://www.ruby-forum.com/.