The document discusses dependency injection (DI) in Magento. It describes the traditional "pull" approach used in Magento where classes directly instantiate dependencies, leading to tightly coupled code. It then introduces the "push" approach using a DI container, where dependencies are injected into classes rather than pulled, reducing coupling. It provides examples of how Magento's object manager implements DI to improve testability and flexibility of classes.

1. Киев
15 сентября 2012
Magento DI

2. Software Entropy
Pull-approach and its problems
Push-approach
Magento Object Manager

3. Software entropy

4. Software entropy cycle

5. Pull-approach

6. Mage::getModel(“Mage_Cms_Model_Page”)
Mage::getSingleton(“Mage_Cms_Model_Page”)

7. class Mage_Cms_Model_Page
{
public function __construct()
{
$this->_idFieldName = Mage::getResourceSingleton($this->_resourceName);
}
public function getAvailableStatuses()
{
$statuses = new Varien_Object(array(
self::STATUS_ENABLED => Mage::helper('Mage_Cms_Helper_Data')->__('Enabled')
self::STATUS_DISABLED => Mage::helper('Mage_Cms_Helper_Data') ->__(„Disabled')
));
Mage::dispatchEvent('cms_page_get_available_statuses', array('statuses' => $statuses));
}
}

8. class Mage_Cms_Model_PageTest extends PHPUnit_Framework_TestCase
{
public function setUp()
{
$this->_page = new Mage_Cms_Model_Page();
}
}

9. class Mage_Cms_Model_PageTest extends PHPUnit_Framework_TestCase
{
public function setUp()
{
Mage::setResourceSingleton(„Page_Resource‟, $this->getMock(„Page_Resource‟));
$this->_page = new Mage_Cms_Model_Page();
}
public function testProcessDoesSomething()
{
Mage::setHelper(„Mage_Cms_Helper_Data‟, $this->getMock(„Mage_Cms_Helper_Data‟));
$this->assertSomething($this->_page->process());
}
}

10. Mage::getXXX() ===

11. Push-approach

12. class Mage_Core_Model_Abstract
{
public function __construct(array $data = array())
{
parent::__construct($data);
$this->_construct();
}
}

13. class Mage_Core_Model_Abstract
{
public function __construct(
Mage_Core_Model_Event_Manager $eventDispatcher,
Mage_Core_Model_Cache $cacheManager,
Mage_Core_Model_Resource_Abstract $resource = null,
Varien_Data_Collection_Db $resourceCollection = null,
array $data = array()
){
$this->_eventDispatcher = $eventDispatcher;
$this->_cacheManager = $cacheManager;
$this->_resource = $resource;
$this->_resourceCollection = $resourceCollection;
parent::__construct($data);
$this->__construct();
}
}

14. Mage::getXXX()
Mage_Some_Class::__construct()
Magento_ObjectManager

15. Magento Object Manager

16. interface Magento_ObjectManager
{
public function get($className, $arguments);
public function create($className, $arguments);
}

18. ZendDi

19. class Mage_Core_Model_Abstract
{
public function __construct(
Mage_Core_Model_Event_Manager $eventDispatcher,
Mage_Core_Model_Cache $cacheManager,
Mage_Core_Model_Resource_Abstract $resource = null,
Varien_Data_Collection_Db $resourceCollection = null,
array $data = array()
){
$this->_eventDispatcher = $eventDispatcher;
$this->_cacheManager = $cacheManager;
$this->_resource = $resource;
$this->_resourceCollection = $resourceCollection;
parent::__construct($data);
$this->__construct();
}
}

20. <config>
<global>
<di>
<Mage_Core_Model_Cache>
<parameters>
<cacheDir>/path/to/cache/dir</cacheDir>
</parameters>
</Mage_Core_Model_Cache>
</di>
</global>
</config>

21. <di>
<Magento_Data_Structure>
<shared>0</shared>
</Magento_Data_Structure>
</di>

22. public function __construct(Some_Interface $processor)

23. <adminhtml>
<di>
<preferences>
<Some_Interface>Some_Backend_Implementation</Some_Interface>
</preferences>
</di>
</adminhtml>
<api>
<di>
<preferences>
<Some_Interface>Some_Api_Implementation</Some_Interface>
</preferences>
</di>
</api>

24. INJECTABLES - NON-INJECTABLES
Varien_Db_Adapter
Mage_Catalog_Model_Product
Mage_Core_Model_Cache
Mage_Wishlist_Model_Wishlist
Mage_Core_Model_Config

25. class Varien_Data_Collection
{
//...
public function getNewEmptyItem()
{
return Mage::getModel($this->_itemObjectClass);
}
//...
}

26. class Varien_Data_Collection
{
public function __construct(Magento_ObjectFactory $factory)
{
$this->_itemFactory = $factory;
}
//...
public function getNewEmptyItem()
{
return $this->_itemFactory->create();
}
//...
}

27. class Mage_Catalog_Model_Product_Factory implements Magento_ObjectManager_Factory
{
protected $_objectManager;
public function __construct(Magento_ObjectManager $objectManager)
{
$this->_objectManager = $objectManager;
}
public function createFromArray(array $arguments = array())
{
return $this->_objectManager->create('Mage_Catalog_Model_Product', $arguments);
}
}

28. class Mage_Review_Model_Observer
{
public function processDeletedProduct (Varien_Event_Observer $observer)
{
$productId = $observer->getEvent()->getProduct()->getId();
if ($productId) {
Mage::getResourceSingleton('Mage_Review_Model_Resource_Review')
->deleteReviewsByProductId($productId);
}
}
}

29. class Mage_Review_Model_Observer
{
public function __construct(Mage_Review_Model_Resource_Review $review)
{
$this->_reviewResource = $reviewResource;
}
//...
}

30. <di>
<Mage_Review_Model_Observer>
<parameters>
<review>
Mage_Review_Model_Resource_Review_Proxy
</review>
</parameters>
</ Mage_Review_Model_Observer >
</di>

31. class Mage_Review_Model_Resource_Review_Proxy
extends Mage_Review_Model_Resource_Review
{
public function __construct(Magento_ObjectManager $objectManager)
{
$this->_objectManager = $objectManager;
}
public function deleteReviewByProductId($productId)
{
return $this->_objectManager
->get('Mage_Review_Model_Resource_Review ')
->deleteReviewByProductId();
}
}