addPluginsDir() — add a directory to the list of directories where plugins are stored
Smarty addPluginsDir(string|array plugins_dir);Example 14.2. addPluginsDir()
<?php
// add directory where plugins are stored
$smarty->addPluginsDir('./plugins_1');
// add multiple directories where plugins are stored
$smarty->setPluginsDir(array(
    './plugins_2',
    './plugins_3',
));
// view the plugins dir chain
var_dump($smarty->getPluginsDir());
// chaining of method calls
$smarty->setPluginsDir('./plugins')
       ->addPluginsDir('./plugins_1')
       ->addPluginsDir('./plugins_2');
?>
   
   See also
   getPluginsDir(),
   setPluginsDir() and
   $plugins_dir.