Question

So – I want to to switch my code to dependency injection, dependency injection container (DIC) paradigm. And I’ve been reading about it… it sorta seems to me that I’ve already been doing that all along… maybe…

What I was doing – I was creating namespaced class (container?), which I’d usually call Api, for each separate project which I’d then instantiate and fetch configured objects from. Actual example:

<?php

/**
 * @namespace
 */
namespace SomeNamespace;

/**
 * api
 */
class api {
    public function __construct() {
        /*
         * Requiring all of the common files.
         */
        require_once( VENDORS_PATH . DIRECTORY_SEPARATOR . 'PHPMailer' . DIRECTORY_SEPARATOR . 'class.phpmailer.php' );
        require_once( VENDORS_PATH . DIRECTORY_SEPARATOR . 'PHPMailer' . DIRECTORY_SEPARATOR . 'class.smtp.php' );
    }

    private function getPostgresqlPreprocessor() {
        $spp = new \SomeNamespace\Utils\PostgresSearchPreProcessor();
        $settingsService = $this->getSettingsService();
        $settings = $settingsService->readSettings();
        $spp->setValidator( new \Auro\Validation\Validator() )
            ->setSettings( $settings )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) );
        return $spp;
    }

    public function getDalApi() {
        return new \DalServices\Api();
    }

    public function getFeedsService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $feedsService = new \SomeNamespace\Feeds();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'feeds' );

        $feedsService
            ->setDalApi( new \DalServices\Api() )
            ->setSomeNamespaceApi( $this )
            ->setResponse( $fc->getResponse() )
            ->setPaginator( new \Auro\View\Paginator() )            
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_feeds_config.php' ) )
            ->setCams( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'webcams.php' ) )
            ->setRenderer( $renderer );
        return $feedsService;
    }

    public function getSettingsService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $settingsService = new \SomeNamespace\Settings;
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'settings' );

        $settingsService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) )
            ->setDalApi( new \DalServices\Api() )
            ->setResponse( $fc->getResponse() )
            ->setRenderer( $renderer );
        return $settingsService;
    }

    public function getUsersService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $usersService = new \SomeNamespace\Users();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'users' );
        $usersService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) )
            ->setAvailableCurrencies( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'currencies.php' ) )
            ->setLanguages( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'languages.php' ) )           
            ->setPostgersqlPreprocessor( $this->getPostgresqlPreprocessor() )
            ->setResponse( $fc->getResponse() )
            ->setDalApi( new \DalServices\Api() )
            ->setRenderer( $renderer );
        return $usersService;
    }

    public function getVrcommentsService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $vrcommentsService = new \SomeNamespace\Vrcomments();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'vrcomments' );
        $vrcommentsService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) )
            ->setPostgersqlPreprocessor( $this->getPostgresqlPreprocessor() )
            ->setPaginator( new \Auro\View\Paginator() )
            ->setResponse( $fc->getResponse() )
            ->setDalApi( new \DalServices\Api() )
            ->setRenderer( $renderer );
        return $vrcommentsService;
    }

    public function getVrentalsService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'vrentals' );
        $vrentalsService = new \SomeNamespace\Vrentals();
        $vrentalsService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) )
            ->setPostgersqlPreprocessor( $this->getPostgresqlPreprocessor() )
            ->setPaginator( new \Auro\View\Paginator() )
            ->setDalApi( new \DalServices\Api() )
            ->setRenderer( $renderer )
            ->setResponse( $fc->getResponse() )
            ->setMailConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_mail.php' ) )
            ->setMailer( new \PHPMailer( true ) );
        return $vrentalsService;
    }

    public function getNoAikService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'noaik' );
        $AikService = new \SomeNamespace\Noaik();
        $noAikService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_config.php' ) )
            ->setPostgersqlPreprocessor( $this->getPostgresqlPreprocessor() )
            ->setPaginator( new \Auro\View\Paginator() )
            ->setResponse( $fc->getResponse() )
            ->setDalApi( new \DalServices\Api() )
            ->setRenderer( $renderer )
            ->setMailConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_craig_mail.php' ) )
            ->setMailer( new \PHPMailer( true ) );
        return $noAikService;
    }

    public function getTotalauthService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $renderer = new \Auro\View\Renderer();
        $renderer->setBasePath( VIEWS_PATH . DIRECTORY_SEPARATOR . 'totalauth' );
        $totalauthService = new \SomeNamespace\Totalauth();
        $totalauthService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setRenderer( $renderer )
            ->setResponse( $fc->getResponse() )
            ->setDalApi( new \DalServices\Api() )
            ->setConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_totalauth_config.php' ) )
            ->setMailConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_totalauth_mail.php' ) )
            ->setMailer( new \PHPMailer( true ) );
        return $totalauthService;
    }

    public function getQuickmailService() {
        $fc = \Auro\Mvc\Front::getInstance();
        $quickmailService = new \SomeNamespace\Quickmail();
        $quickmailService
            ->setSomeNamespaceApi( $this )
            ->setValidator( new \Auro\Validation\Validator() )
            ->setResponse( $fc->getResponse() )
            ->setMailConfig( require( CONFIGS_PATH . DIRECTORY_SEPARATOR . 'models_quickmail_mail.php' ) )
            ->setMailer( new \PHPMailer( true ) );
        return $quickmailService;
    }
}

?>

Could someone confirm that this is in fact dependency injection container and what can be improved?

Answer 1

To me this looks like a collection of methods to instantiate objects needed by the specific API. I don’t know that I would consider it dependency injection in and of itself. It is hard to tell though without seeing how this class is actually used. To me, a dependency injection container would basically containe metadata about how to instantiate various classes that implement a common interface.

So a sample set of classes that might interact to achieve dependency injection might look like:

class db_dependency_provider {
    private static $class_map = array(
        'postgres' => 'postgres_abstraction_class',
        'mysql' => 'mysql_abstraction_class',
        'oracle' => 'oracle_abstraction_class'
    }

    public static function get_db_abstraction($type) {
        $class = self::$class_map[$type];
        return new $class();
    }
}

interface db_abstraction_interface {
    public function connect();
    public function query($query);
    // etc.
}

class mysql_db_abstraction implements db_abstraction_interface {
    // actual implementation
}

class postgres_db_abstraction implements db_abstraction_interface {
    // actual implementation
}

class some_class_that_needs_a_db {
    $db = null;
    public function __construct($db) {
        $this->db = $db;
    }
    // other methods
}

// use dependency injection container
$class = new some_class_that_needs_a_db(db_dependency_provider::get_db_abstraction('mysql'));