Question

Having php code:

function getChildren($parent_id = 0)
{
....
return $SomeChildrenArray;
}

And Smarty assignation $smarty->assign('children', getChildren($id));

How to write smarty expression to pass some value to the function?

Answer 1

Smarty can be extended through its plugins API. See registerPlugin() for an introduction.

$smarty->registerPlugin('function', 'children', function($params, $template) {
  return "some string:" . $params['foobar'];
});

and

{children foobar="hello world"}

would output

some string:hello world

Note that plugin functions have to return a string.

---

Since Smarty3 you can call and assign arbitrary functions from within a template:

{$children = getChildren(3)}

This way you can call any function and return any value/type you want. See Smarty_Security for details on how to control which functions may be called…