>>>>> "M" == Michael Neumann <mneumann / ntecs.de> writes: M> But why does this work: M> a = [] M> hash[a] = "test" M> a[0] = "1" M> p hash.keys M> # => returns [ ["1"] ] uln% cat b.rb #!/usr/local/bin/ruby a = [] hash = { a => "test"} a[0] = "1" p hash[a] uln% uln% b.rb nil uln% Guy Decoux