class ActiveSupport::Cache::MemCacheStore

def initialize(*addresses)

MemCacheStore will connect to localhost:11211 (the default memcached port).
If no addresses are provided, but ENV['MEMCACHE_SERVERS'] is defined, it will be used instead. Otherwise,

ActiveSupport::Cache::MemCacheStore.new("localhost", "server-downstairs.localnetwork:8229")

in the form of "host_name:port". For example:
addresses. Each address is either a host name, or a host-with-port string
Creates a new MemCacheStore object, with the given memcached server 
def initialize(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  if options.key?(:cache_nils)
    options[:skip_nil] = !options.delete(:cache_nils)
  end
  super(options)
  unless [String, Dalli::Client, NilClass].include?(addresses.first.class)
    raise ArgumentError, "First argument must be an empty array, an array of hosts or a Dalli::Client instance."
  end
  if addresses.first.is_a?(Dalli::Client)
    @data = addresses.first
  else
    mem_cache_options = options.dup
    # The value "compress: false" prevents duplicate compression within Dalli.
    mem_cache_options[:compress] = false
    (UNIVERSAL_OPTIONS - %i(compress)).each { |name| mem_cache_options.delete(name) }
    @data = self.class.build_mem_cache(*(addresses + [mem_cache_options]))
  end
end