Searching for an elegant way in PHP for loading dependencies/services/configuration?

Question

I\'m building a MVC PHP framework and I wonder which are the best practices to load what I need in my classes, be it other classes or plain configuration.

Till today

Answer 1

Why reinvent the wheel? Use Pimple as your DI container, and learn how to use it from its documentation.

Or, use Silex microframework as a base to create your own framework. It extends Pimple functionality, so you can use dependency injection.

To answer your question, this is how you use a DI without coupling your classes to it:

interface ContainerInterface {
    public function getService($service_name);
    public function registerService($service_name,Closure $service_definition);
}

class Application {
    public function __construct(ContainerInterface $container) {
        $this->container= $container;
    }

    public function run() {
        // very simple to use!
        $this->container->getService('db')->someDatabaseQuery();
    }
}

$c = new My_DI_Container;

// Service definitions could be in a separate file
$c->registerService('db',function() { return new Database('some config'); });

// Then you inject your DI container into the objects that need it
$app = new Application($c);
$app->run(); // or whatever

This way, the DI container is decoupled and in the future you could use a different implementation. The only requirement is that it implements the ContainerInterface.

Note that the container object is being pushed, and not pulled. Avoid using singleton. To get/set single-instance objects, use the container (that's its responsibility). And to get the container instance, just push it through constructors.