deep_copy.rb

def deep_copy(object)
  case object
  when Array
    object.map { |item| deep_copy(item) }
  when Hash
    object.inject({}) do |hash, (key,value)|
      hash[deep_copy(key)] = deep_copy(value)
      hash
    end
  # handle other data structures if need be
  else
    object.respond_to?(:dup) ? object.dup : object
  end
end

The slower, but simpler approach:

def deep_copy(object)
  Marshal.load(Marshal.dump(object))
end