module ActiveSupport::Cache

def expand_cache_key(key, namespace = nil)

def expand_cache_key(key, namespace = nil)
  expanded_cache_key = namespace ? "#{namespace}/" : ""
  if prefix = ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]
    expanded_cache_key << "#{prefix}/"
  end
  expanded_cache_key << retrieve_cache_key(key)
  expanded_cache_key
end

def lookup_store(*store_option)

# => returns MyOwnCacheStore.new
ActiveSupport::Cache.lookup_store(MyOwnCacheStore.new)

If the first argument is not a Symbol, then it will simply be returned:

# => same as: ActiveSupport::Cache::FileStore.new("/tmp/cache")
ActiveSupport::Cache.lookup_store(:file_store, "/tmp/cache")

class's constructor:
Any additional arguments will be passed to the corresponding cache store

# => returns a new ActiveSupport::Cache::MemCacheStore object
ActiveSupport::Cache.lookup_store(:mem_cache_store)

# => returns a new ActiveSupport::Cache::MemoryStore object
ActiveSupport::Cache.lookup_store(:memory_store)

For example:
store class under the ActiveSupport::Cache namespace will be created.
If you pass a Symbol as the first argument, then a corresponding cache

ActiveSupport::Cache::MemoryStore object will be returned.
If no arguments are passed to this method, then a new

Creates a new CacheStore object according to the given options.
def lookup_store(*store_option)
  store, *parameters = *Array.wrap(store_option).flatten
  case store
  when Symbol
    store_class_name = store.to_s.camelize
    store_class =
      begin
        require "active_support/cache/#{store}"
      rescue LoadError => e
        raise "Could not find cache store adapter for #{store} (#{e})"
      else
        ActiveSupport::Cache.const_get(store_class_name)
      end
    store_class.new(*parameters)
  when nil
    ActiveSupport::Cache::MemoryStore.new
  else
    store
  end
end

def retrieve_cache_key(key)

def retrieve_cache_key(key)
  case
  when key.respond_to?(:cache_key) then key.cache_key
  when key.is_a?(Array)            then key.map { |element| retrieve_cache_key(element) }.to_param
  else                                  key.to_param
  end.to_s
end