Zend Framework 2 getControllerConfig vs getConfig - php

Question

I am listening to this talk here : https://www.youtube.com/watch?v=Vp7y65rnN98
At the 44:00 Module.php::getConfig() vs Module.php::getControllerConfig()
looking at an example module like ZFCampuses zf-apigility-admin module ...
I see BOTH config/module.config.php and Module.php::getControllerConfig() defining Controller Factories.
zf-apigility/config/module.config.php
'controllers' => array(
'aliases' => array(
'ZF\Apigility\Admin\Controller\HttpBasicAuthentication' => 'ZF\Apigility\Admin\Controller\Authentication',
'ZF\Apigility\Admin\Controller\HttpDigestAuthentication' => 'ZF\Apigility\Admin\Controller\Authentication',
'ZF\Apigility\Admin\Controller\OAuth2Authentication' => 'ZF\Apigility\Admin\Controller\Authentication',
),
'invokables' => array(
'ZF\Apigility\Admin\Controller\App' => 'ZF\Apigility\Admin\Controller\AppController',
'ZF\Apigility\Admin\Controller\CacheEnabled' => 'ZF\Apigility\Admin\Controller\CacheEnabledController',
'ZF\Apigility\Admin\Controller\FsPermissions' => 'ZF\Apigility\Admin\Controller\FsPermissionsController',
),
'factories' => array(
'ZF\Apigility\Admin\Controller\Documentation' => 'ZF\Apigility\Admin\Controller\DocumentationControllerFactory',
'ZF\Apigility\Admin\Controller\Filters' => 'ZF\Apigility\Admin\Controller\FiltersControllerFactory',
'ZF\Apigility\Admin\Controller\Hydrators' => 'ZF\Apigility\Admin\Controller\HydratorsControllerFactory',
'ZF\Apigility\Admin\Controller\Validators' => 'ZF\Apigility\Admin\Controller\ValidatorsControllerFactory',
'ZF\Apigility\Admin\Controller\InputFilter' => 'ZF\Apigility\Admin\Controller\InputFilterControllerFactory',
),
),
zf-apigility/Module.php
public function getControllerConfig()
{
return array('factories' => array(
'ZF\Apigility\Admin\Controller\Authentication' => function ($controllers) {
$services = $controllers->getServiceLocator();
$model = $services->get('ZF\Apigility\Admin\Model\AuthenticationModel');
return new Controller\AuthenticationController($model);
},
'ZF\Apigility\Admin\Controller\Authorization' => function ($controllers) {
$services = $controllers->getServiceLocator();
$factory = $services->get('ZF\Apigility\Admin\Model\AuthorizationModelFactory');
return new Controller\AuthorizationController($factory);
},
'ZF\Apigility\Admin\Controller\Config' => function ($controllers) {
$services = $controllers->getServiceLocator();
return new Controller\ConfigController($services->get('ZF\Configuration\ConfigResource'));
},
'ZF\Apigility\Admin\Controller\ModuleConfig' => function ($controllers) {
$services = $controllers->getServiceLocator();
return new Controller\ModuleConfigController($services->get('ZF\Configuration\ConfigResourceFactory'));
},
'ZF\Apigility\Admin\Controller\ModuleCreation' => function ($controllers) {
$services = $controllers->getServiceLocator();
$model = $services->get('ZF\Apigility\Admin\Model\ModuleModel');
return new Controller\ModuleCreationController($model);
},
'ZF\Apigility\Admin\Controller\Source' => function ($controllers) {
$services = $controllers->getServiceLocator();
$model = $services->get('ZF\Apigility\Admin\Model\ModuleModel');
return new Controller\SourceController($model);
},
'ZF\Apigility\Admin\Controller\Versioning' => function ($controllers) {
$services = $controllers->getServiceLocator();
$factory = $services->get('ZF\Apigility\Admin\Model\VersioningModelFactory');
return new Controller\VersioningController($factory);
},
));
}
My question is, why is this doubling up occurring here? What am I missing about the usage of Module.php::getControllerConfig() vs merely listing the Factories in Module.config.php ?
Edit : I think I found the answer to my question here https://stackoverflow.com/a/22374072/389976

Answer 1

You'll see that all the factories defined in Module.php use closures (AKA anonymous functions). The convention is for all config to go into module.config.php except for the closures.
ZF has built-in functionality (disabled by default) to cache the merged config files, but it can't do that if the config file contains closures, as these cannot be serialized, and thus are not cacheable. By keeping them separate you can enable config caching, which improves performance.
Edit: Perhaps we're talking at crossed purposes a little here. My answer above hopefully explains why the closures from Module.php shouldn't be moved to the module config file. You could of course create factory classes for each of the closures defined, and then list those in the module config. Some would consider this best practice (personally I rarely do this). At this point it's a trade off between ease of development and performance. It's much more convenient to create a four line closure than create a whole new class.