$default_resource_type
默认源类型变量

This tells smarty what resource type to use implicitly. The default value is 'file', meaning that $smarty->display('index.tpl'); and $smarty->display('file:index.tpl'); are identical in meaning. See the resource chapter for details.
该变量告诉smarty隐式地使用什么源类型.默认值为'file',也就是说,$smarty->display('index.tpl');和and $smarty->display('file:index.tpl');从意思上是一样的.祥见resource一章。