class ActiveSupport::Cache::Store

def expanded_key(key) # :nodoc:

:nodoc:
called. If the key is a Hash, then keys will be sorted alphabetically.
object responds to +cache_key+. Otherwise, +to_param+ method will be
Expand key to be a consistent string value. Invoke +cache_key+ if 
def expanded_key(key) # :nodoc:
  return key.cache_key.to_s if key.respond_to?(:cache_key)
  case key
  when Array
    if key.size > 1
      key = key.collect{|element| expanded_key(element)}
    else
      key = key.first
    end
  when Hash
    key = key.sort_by { |k,_| k.to_s }.collect{|k,v| "#{k}=#{v}"}
  end
  key.to_param
end