$controller = Mage::getControllerInstance('catalog', 'category'); $controller->indexAction();
$controller = Mage::getControllerInstance('customer', 'accountLogin'); $controller->loginPostAction();
$controller = Mage::getControllerInstance('checkout', 'cart'); $controller->addAction();In this example, we are retrieving an instance of the `Checkout_CartController` class and calling its `addAction()` method. Package Library: Magento Checkout Module