From: ts Date: 2006-04-03T18:34:50+09:00 Subject: Re: What does this hash do? Is this a hash? >>>>> "r" == ralf writes: r> hash = Hash.new("") r> => {} r> hash["a"] << "b" When you write this : 1) ruby return the default value for the hash ('a' don't exist as a key) 2) concatenate "b" to this default value (see String#<<) Finally you have modified the default value for the hash, and you can see this here : r> hash["alskj"] r> => "b" ruby now give the new default value Guy Decoux