<?php
$config->set([
    'database' => function() {
        static $connection;
		if (!isset($connection)) {
		    $connection = new PDO(...);
		}
		return $connection;
    },
	'solr' => function() {
        static $connection;
		if (!isset($connection)) {
		    $connection = new Solarium\Client(...);
		}
		return $connection;
	},
	'cache' => function() {
        static $connection;
		if (!isset($connection)) {
		    $connection = new Memcache(...);
		}
		return $connection;
	},
]);