$undefined
未定義變量
This sets the value of $undefined for Smarty, default is null.
Currently this is only used to set undefined variables in
$global_assign to a default value.
該變量為Smarty設(shè)定沒有得到定義的變量的值,默認(rèn)為空.當(dāng)前僅用來設(shè)定全局配置中的未定義變量為一個(gè)默認(rèn)值.