Magento Module – Understanding the Use of `_notes`

Caveats: There's no designed way to do what you're asking in the system. The following should work, but I've never tried it out extensively on a production system, and there may be situations where it will cause more trouble that it's worth. Only proceed if you're comfortable debugging problems related to the changing the rewrites of a working system.

Step 1 is undoing the rewrite. The Magento configuration tree can be changed at runtime. So, if you run the following code

$config = Mage::getConfig();        
$config->setNode(
    'global/blocks/catalog/rewrite/product_list_toolbar',
    'Mage_Catalog_Block_Product_List_Toolbar'
);

Then Magento will instantiate the original Mage_Catalog_Block_Product_List_Toolbar block for the remainder of the request.

Step 2 is deciding where to call this in your module. Since this is just for your controller and it's rewriting a block that won't be instantiated until the end of your controller, I'd add a method to your controller class something like this

protected function _undoRewrites()
{
    $config = Mage::getConfig();        
    $config->setNode(
        'global/blocks/catalog/rewrite/product_list_toolbar',
        'Mage_Catalog_Block_Product_List_Toolbar'
    );    
}

and then just call this method at the start of each of your actions

public function indexAction()
{
    $this->_undoRewrites();
    $test = Mage::getSingleton('core/layout')->createBlock('catalog/product_list_toolbar');        
    var_dump($test);
}

This may seem a little clunky, but I think it's a good idea to be clunky (i.e. obvious) when you're being clever with Magento's system objects. Another place for this could be the controller_action_predispatch or controller_action_predispatch_front_controller_action events and/or applied conditionally.

Just remember the rewrite won't be undone until this method is called. That means if you attempt to instantiate a block before calling _undoRewrites, the rewritten class will be used to instantiate the object.

To run your extension again you need to remove your extension entry from setup_module table also remove your table which are created by your extension script then run below command

php bin/magento setup:upgrade

Thanks