$trusted_dir is only for use when $security is enabled. This is an array
of all directories that are considered trusted. Trusted directories are
where you keep php scripts that are executed directly from the templates
with {include_php}.
信任目录变量仅用在$security启动之后.这是一个所有建立信任的目录数组变量.你可以将php脚本放到这些信任目录中,这些脚本会直接在模板里以{include_php}标记得到执行.