1<?php
2
3/*
4 * This file is part of the Symfony package.
5 *
6 * (c) Fabien Potencier <fabien@symfony.com>
7 *
8 * For the full copyright and license information, please view the LICENSE
9 * file that was distributed with this source code.
10 */
11
12namespace Symfony\Contracts\Service;
13
14/**
15 * A ServiceSubscriber exposes its dependencies via the static {@link getSubscribedServices} method.
16 *
17 * The getSubscribedServices method returns an array of service types required by such instances,
18 * optionally keyed by the service names used internally. Service types that start with an interrogation
19 * mark "?" are optional, while the other ones are mandatory service dependencies.
20 *
21 * The injected service locators SHOULD NOT allow access to any other services not specified by the method.
22 *
23 * It is expected that ServiceSubscriber instances consume PSR-11-based service locators internally.
24 * This interface does not dictate any injection method for these service locators, although constructor
25 * injection is recommended.
26 *
27 * @author Nicolas Grekas <p@tchwork.com>
28 */
29interface ServiceSubscriberInterface
30{
31    /**
32     * Returns an array of service types required by such instances, optionally keyed by the service names used internally.
33     *
34     * For mandatory dependencies:
35     *
36     *  * ['logger' => 'Psr\Log\LoggerInterface'] means the objects use the "logger" name
37     *    internally to fetch a service which must implement Psr\Log\LoggerInterface.
38     *  * ['loggers' => 'Psr\Log\LoggerInterface[]'] means the objects use the "loggers" name
39     *    internally to fetch an iterable of Psr\Log\LoggerInterface instances.
40     *  * ['Psr\Log\LoggerInterface'] is a shortcut for
41     *  * ['Psr\Log\LoggerInterface' => 'Psr\Log\LoggerInterface']
42     *
43     * otherwise:
44     *
45     *  * ['logger' => '?Psr\Log\LoggerInterface'] denotes an optional dependency
46     *  * ['loggers' => '?Psr\Log\LoggerInterface[]'] denotes an optional iterable dependency
47     *  * ['?Psr\Log\LoggerInterface'] is a shortcut for
48     *  * ['Psr\Log\LoggerInterface' => '?Psr\Log\LoggerInterface']
49     *
50     * @return array The required service types, optionally keyed by service names
51     */
52    public static function getSubscribedServices();
53}
54