Symfony 7.4 Contracts Component

GitHub: https://github.com/symfony/contracts Docs: https://symfony.com/doc/7.4/components/contracts.html

Quick Reference

What Are Contracts?

Contracts are a set of PHP interfaces, traits, and normative docblocks extracted from Symfony components. They provide abstractions for loose coupling and interoperability.

Installation

bash

composer require symfony/cache-contracts
composer require symfony/event-dispatcher-contracts
composer require symfony/deprecation-contracts
composer require symfony/http-client-contracts
composer require symfony/service-contracts
composer require symfony/translation-contracts

Using Contracts as Type Hints

php

use Symfony\Contracts\Cache\CacheInterface;

class MyService
{
    public function __construct(
        private CacheInterface $cache,
    ) {}

    public function getData(): array
    {
        return $this->cache->get('my_key', function () {
            return $this->computeExpensiveData();
        });
    }
}

Service Contracts (Autowiring)

php

use Symfony\Contracts\Service\ServiceSubscriberInterface;
use Psr\Container\ContainerInterface;

class MyController implements ServiceSubscriberInterface
{
    public function __construct(private ContainerInterface $locator) {}

    public static function getSubscribedServices(): array
    {
        return [
            'logger' => LoggerInterface::class,
        ];
    }
}

Declaring Implementation in composer.json

json

{
    "provide": {
        "symfony/cache-implementation": "3.0"
    }
}

Key Contract Packages

Package	Interfaces
`cache-contracts`	`CacheInterface`, `TagAwareCacheInterface`, `CallbackInterface`
`event-dispatcher-contracts`	`EventDispatcherInterface`
`http-client-contracts`	`HttpClientInterface`, `ResponseInterface`
`service-contracts`	`ServiceSubscriberInterface`, `ResetInterface`, `ServiceProviderInterface`
`translation-contracts`	`TranslatorInterface`, `LocaleAwareInterface`
`deprecation-contracts`	`trigger_deprecation()` function

Full Documentation

For complete details including design principles, differences from PHP-FIG PSRs, and all available interfaces, see references/contracts.md.