下列常量由此擴展定義，且僅在此擴展編譯入 PHP 或在運行時(shí)動(dòng)態(tài)載入時(shí)可用。
YAF_VERSION
(string)
YAF_ENVIRON
(string)
YAF_ERR_STARTUP_FAILED
(integer)
YAF_ERR_ROUTE_FAILED
(integer)
YAF_ERR_DISPATCH_FAILED
(integer)
YAF_ERR_AUTOLOAD_FAILED
(integer)
YAF_ERR_NOTFOUND_MODULE
(integer)
YAF_ERR_NOTFOUND_CONTROLLER
(integer)
YAF_ERR_NOTFOUND_ACTION
(integer)
YAF_ERR_NOTFOUND_VIEW
(integer)
YAF_ERR_CALL_FAILED
(integer)
YAF_ERR_TYPE_ERROR
(integer)