Black Magic of Code Generation in Magento 2

#mm15de
@SergiiShymko
Senior Software Engineer
Magento, an eBay Inc. company
Code Generation
in Magento 2

#mm15de
Introduction to Code Generation
• Automatic programming – generation of computer program
• Source code generation
– Generation based on template
• Allows to write code at higher abstraction level
• Enables aspect-oriented programming (AOP)
• Enables generic programming – parameterization over types
• Avoids writing boilerplate code

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Code Generation in Magento 1.x

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Code Generation in Magento 2

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Code Generation in Magento 2
• Code is generated:
– On the fly (development)
• Autoload non-existing class that follows naming pattern
– Beforehand (production)
• Run CLI tools
php dev/tools/Magento/Tools/Di/compiler.php
• Location of generated code:
var/generation/

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Factories
• Factory creates objects
• Single method – create()
• Used for non-injectables, i.e. entities
• Isolation from Object Manager
• Type safety
• IDE auto-completion
• Class name pattern:
NamespaceClassFactory

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Factory Usage
namespace MagentoCatalogModelProduct;
class Copier
{
public function __construct(
MagentoCatalogModelProductFactory $productFactory
) {
$this->productFactory = $productFactory;
}
public function copy(MagentoCatalogModelProduct $product) {
$duplicate = $this->productFactory->create();
// ...
}
}
app/code/Magento/Catalog/Model/Product/Copier.php

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Generated Factory (Simplified)
namespace MagentoCatalogModel;
class ProductFactory
{
MagentoFrameworkObjectManagerInterface $objectManager
) {
$this->objectManager = $objectManager;
}
public function create(array $data = array()) {
return $this->objectManager->create(
'MagentoCatalogModelProduct',
$data
);
}
}
var/generation/Magento/Catalog/Model/ProductFactory.php

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Proxies
• Implementation of GoF pattern
• Follows interface of subject
• Delays creation of subject
– Delays creation of dependencies
• Forwards calls to subject
• Used for optional dependencies of DI
NamespaceClassProxy

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Proxy Usage in DI Config
<config>
<type name="MagentoCatalogModelResourceProductCollection">
<arguments>
<argument name="customerSession" xsi:type="object">
MagentoCustomerModelSessionProxy
</argument>
</arguments>
</type>
</config>
app/code/Magento/Catalog/etc/di.xml

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Generated Proxy (Simplified)
namespace MagentoCustomerModelSession;
class Proxy extends MagentoCustomerModelSession
{
protected function getSubject() {
if (!$this->subject) {
$this->subject = $this->objectManager->get(
'MagentoCustomerModelSession'
);
}
return $this->subject;
}
public function getCustomerId() {
return $this->getSubject()->getCustomerId();
}
// ...
}
var/generation/Magento/Customer/Model/Session/Proxy.php

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Interception
• Primary customization approach
• AOP-like mechanism
• Used for plugins
• Attach behavior to public methods
– Before
– After
– Around
• Plugins declared in DI config

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Plugin Implementation
namespace MagentoStoreAppActionPlugin;
class StoreCheck
{
public function aroundDispatch(
MagentoFrameworkAppActionAction $subject,
Closure $proceed,
MagentoFrameworkAppRequestInterface $request
) {
if (!$this->storeManager->getStore()->getIsActive()) {
throw new MagentoFrameworkAppInitException(
'Current store is not active.'
);
}
return $proceed($request);
}
}
app/code/Magento/Store/App/Action/Plugin/StoreCheck.php

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Plugin Declaration in DI Config
<config>
<type name="MagentoFrameworkAppActionAction">
<plugin name="storeCheck"
type="MagentoStoreAppActionPluginStoreCheck"
sortOrder="10"/>
</type>
</config>
app/code/Magento/Store/etc/di.xml

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Generated Interceptor (Simplified)
namespace MagentoFrameworkAppActionAction;
class Interceptor extends MagentoFrameworkAppActionAction
{
public function dispatch(
MagentoFrameworkAppRequestInterface $request
) {
$pluginInfo = $this->pluginList->getNext(
'MagentoFrameworkAppActionAction', 'dispatch'
);
if (!$pluginInfo) {
return parent::dispatch($request);
} else {
return $this->___callPlugins(
'dispatch', func_get_args(), $pluginInfo
);
}
}
}
var/generation/Magento/Framework/App/Action/Action/Interceptor.php

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Code Generation for Service Layer
• Service layer – ultimate public API
• Services implement stateless operations
• Generated code:
– Repository*
– Persistor*
– Search Results
– Extension Attributes
* – may be removed in future releases

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Generated Repository (Simplified)
namespace MagentoSalesApiDataOrder;
class Repository implements MagentoSalesApiOrderRepositoryInterface
{
MagentoSalesApiDataOrderInterfacePersistor $orderPersistor,
MagentoSalesApiDataOrderSearchResultInterfaceFactory $searchResultFactory
) {
$this->orderPersistor = $orderPersistor;
$this->searchResultFactory = $searchResultFactory;
}
public function get($id);
public function create(MagentoSalesApiDataOrderInterface $entity);
public function getList(MagentoFrameworkApiSearchCriteria $criteria);
public function remove(MagentoSalesApiDataOrderInterface $entity);
public function flush();
}
var/generation/Magento/Sales/Api/Data/Order/Repository.php

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Extension Attributes
• Extension to data interfaces from 3rd party modules
• Attributes declared in configuration
• Attribute getters/setters generated
• Type-safe attribute access
• IDE auto-completion
NamespaceClassExtensionInterface
NamespaceClassExtension

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Declaration of Extension Attributes
<config>
<custom_attributes for="MagentoCatalogApiDataProductInterface">
<attribute code="price_type" type="integer" />
</custom_attributes>
</config>
app/code/Magento/Bundle/etc/data_object.xml

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Entity with Extension Attributes
namespace MagentoCatalogApiData;
interface ProductInterface
extends MagentoFrameworkApiCustomAttributesDataInterface
{
/**
* @return MagentoCatalogApiDataProductExtensionInterface|null
*/
public function getExtensionAttributes();
public function setExtensionAttributes(
MagentoCatalogApiDataProductExtensionInterface $attributes
);
// ...
}
app/code/Magento/Catalog/Api/Data/ProductInterface.php

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Generated Interface of Extension Attributes
interface ProductExtensionInterface
extends MagentoFrameworkApiExtensionAttributesInterface
{
/**
* @return integer
*/
public function getPriceType();
/**
* @param integer $priceType
* @return $this
*/
public function setPriceType($priceType);
// ...
}
var/generation/Magento/Catalog/Api/Data/ProductExtensionInterface.php

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Generated Implementation of Extension Attributes
class ProductExtension
extends MagentoFrameworkApiAbstractSimpleObject
implements MagentoCatalogApiDataProductExtensionInterface
{
/**
* @return integer
*/
public function getPriceType() {
return $this->_get('price_type');
}
/**
* @param integer $priceType
* @return $this
*/
public function setPriceType($priceType) {
return $this->setData('price_type', $priceType);
}
// ...
}
var/generation/Magento/Catalog/Api/Data/ProductExtension.php

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Loggers
• Implementation of GoF pattern Decorator
• Activated with the profiler
– Object Manager wraps instances with loggers
• Tracks method call stack
• Forwards calls to original methods
NamespaceClassLogger

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Summary of Code Generation
• DI
– Factory
– Proxy
• Interception
• Service Layer
– Repository
– Persistor
– Search Results
– Extension Attributes
• Logger

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Thank You!
Q & A
@SergiiShymko
sshymko@ebay.com
sergey@shymko.net

Black Magic of Code Generation in Magento 2

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