code: public static function setCacheType(string $sCacheName)
  	{
  		if ($sCacheName === 'file') { self::$_sTypeOfCache = 'file'; }
  		else if ($sCacheName === 'memcache') { self::$_sTypeOfCache = 'memcache'; }
  		else if ($sCacheName === 'apc') { self::$_sTypeOfCache = 'apc'; }
  		else if ($sCacheName === 'redis') { self::$_sTypeOfCache = 'redis'; }
  		else { self::$_sTypeOfCache = 'mock'; }
  	}
docs: set the cache that we would use
  
  @access private
  @param  string $sCacheName name of cache
  @return object