callable.php

<?php
class Callable {

    public function __invoke(array $options) {
        print_r($options);
    }
}

class Model {

    public $attribute;

    public function __construct() {
        $this->attribute = new Callable();
    }
}

$callable = new Callable();
$callable(array('conditions' => '1 = 1'));

$model = new Model();
$model->attribute(array('order' => 'name ASC'));
?>

#############
## OUTPUT

Array
(
   [conditions] => 1 = 1
)

Fatal error: Call to undefined method Model::attribute() in /home/rafael/projects/php53/callable.php on line 22