Inject logger in objects using dependency injection

logger-aware.php

<?php

require __DIR__.'/vendor/autoload.php';

use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use Monolog\Logger;

interface LoggerAwareInterface
{
    public function setLogger(LoggerInterface $logger);
}

// Foobar is an example of object using a logger
class Foobar implements LoggerAwareInterface
{
    protected $logger;

    public function __construct()
    {
        $this->logger = new NullLogger();
    }

    public function setLogger(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function doFoo()
    {
        $this->logger->debug('I\'m doin foo!');
        // Doin some foo process...
    }
}

// Extend the DIC to do the hook
class Container extends Pimple
{
    protected $logger;

    public function __construct($debug = false)
    {
        if ($debug) {
            $this->logger = new Logger('test');
        }
    }

    public function offsetGet($id)
    {
        $object = parent::offsetGet($id);

        // Here is the hook: inject the logger
        if (null !== $this->logger && $object instanceof LoggerAwareInterface) {
            $object->setLogger($this->logger);
        }

        return $object;
    }
}

$container = new Container(true); // try to change it to false
$container['foo'] = $container->share(function() {
    return new Foobar();
});

$container['foo']->doFoo();