Constants {#smarty.constants} ========= SMARTY\_DIR {#constant.smarty.dir} =========== This is the **full system path** to the location of the Smarty class files. If this is not defined in your script, then Smarty will attempt to determine the appropriate value automatically. If defined, the path **must end with a trailing slash/**. See also [`$smarty.const`](../designers/language-variables/language-variables-smarty.md).