# Custom Bundles (Symfony) > Bundle creation, extension configuration, compiler passes, reusable bundles, best practices - 20 interview questions - Senior - [Interview Questions: Symfony](https://sharpskill.dev/en/technologies/symfony/interview-questions.md) ## 1. Which class must the main bundle class extend in Symfony? **Answer** The main bundle class in Symfony must extend AbstractBundle (Symfony 6.1+) or Bundle. AbstractBundle is recommended as it simplifies configuration and allows defining configuration directly in the bundle class via the configure() method. Bundle remains available for backward compatibility but AbstractBundle offers a more modern API. ## 2. What is the role of the Extension class in a Symfony bundle? **Answer** The Extension class (extending ConfigurableExtension or Extension) is responsible for loading the bundle configuration and registering services in the container. It reads the bundle's configuration files, processes application parameters, and configures services via the ContainerBuilder. It implements the load() method which is called during container compilation. ## 3. What is the naming convention for the main class of a bundle named AcmePaymentBundle? **Answer** By Symfony convention, the main bundle class must have the same name as the bundle. For AcmePaymentBundle, the main class will be AcmePaymentBundle and must be in the corresponding namespace, typically Acme\PaymentBundle. The file will therefore be AcmePaymentBundle.php in the bundle's src/ folder. ## 17 more questions available - What is a Compiler Pass in Symfony and when should it be used? - How to define semantic configuration for a bundle with parameter validation? Sign up for free: https://sharpskill.dev/en/login ## Other Symfony interview topics - [Modern PHP (8.1+)](https://sharpskill.dev/en/technologies/symfony/interview-questions/php-modern-features.md): 20 questions, Junior - [Symfony Basics](https://sharpskill.dev/en/technologies/symfony/interview-questions/symfony-basics.md): 25 questions, Junior - [Routing & Controllers](https://sharpskill.dev/en/technologies/symfony/interview-questions/routing-controllers.md): 20 questions, Junior - [Twig & Templates](https://sharpskill.dev/en/technologies/symfony/interview-questions/twig-templates.md): 20 questions, Junior - [Doctrine ORM Basics](https://sharpskill.dev/en/technologies/symfony/interview-questions/doctrine-orm-basics.md): 25 questions, Junior - [Symfony Forms](https://sharpskill.dev/en/technologies/symfony/interview-questions/forms.md): 22 questions, Junior - [Data Validation](https://sharpskill.dev/en/technologies/symfony/interview-questions/validation.md): 18 questions, Junior - [Dependency Injection & Services](https://sharpskill.dev/en/technologies/symfony/interview-questions/dependency-injection.md): 24 questions, Mid-Level - [Security & Authentication](https://sharpskill.dev/en/technologies/symfony/interview-questions/security-authentication.md): 26 questions, Mid-Level - [Doctrine Advanced](https://sharpskill.dev/en/technologies/symfony/interview-questions/doctrine-advanced.md): 24 questions, Mid-Level - [API Platform](https://sharpskill.dev/en/technologies/symfony/interview-questions/api-platform.md): 22 questions, Mid-Level - [Serializer Component](https://sharpskill.dev/en/technologies/symfony/interview-questions/serializer.md): 20 questions, Mid-Level - [Events & Event Subscribers](https://sharpskill.dev/en/technologies/symfony/interview-questions/events-subscribers.md): 20 questions, Mid-Level - [Console & Commands](https://sharpskill.dev/en/technologies/symfony/interview-questions/console-commands.md): 18 questions, Mid-Level - [Messenger Component](https://sharpskill.dev/en/technologies/symfony/interview-questions/messenger.md): 22 questions, Mid-Level - [HTTP Client](https://sharpskill.dev/en/technologies/symfony/interview-questions/http-client.md): 18 questions, Mid-Level - [Cache & Performance](https://sharpskill.dev/en/technologies/symfony/interview-questions/cache.md): 20 questions, Mid-Level - [Workflow Component](https://sharpskill.dev/en/technologies/symfony/interview-questions/workflow.md): 18 questions, Mid-Level - [Testing Symfony](https://sharpskill.dev/en/technologies/symfony/interview-questions/testing.md): 22 questions, Mid-Level - [Mailer Component](https://sharpskill.dev/en/technologies/symfony/interview-questions/mailer.md): 16 questions, Mid-Level - [Translations & i18n](https://sharpskill.dev/en/technologies/symfony/interview-questions/translations.md): 16 questions, Mid-Level - [EasyAdmin Bundle](https://sharpskill.dev/en/technologies/symfony/interview-questions/easyadmin.md): 18 questions, Mid-Level - [Symfony Architecture](https://sharpskill.dev/en/technologies/symfony/interview-questions/architecture-patterns.md): 24 questions, Senior - [Performance & Optimization](https://sharpskill.dev/en/technologies/symfony/interview-questions/performance-optimization.md): 22 questions, Senior - [Security Advanced](https://sharpskill.dev/en/technologies/symfony/interview-questions/security-advanced.md): 22 questions, Senior - [Microservices with Symfony](https://sharpskill.dev/en/technologies/symfony/interview-questions/microservices.md): 22 questions, Senior - [Real-time & WebSockets](https://sharpskill.dev/en/technologies/symfony/interview-questions/real-time.md): 18 questions, Senior - [Deployment & DevOps](https://sharpskill.dev/en/technologies/symfony/interview-questions/deployment-devops.md): 20 questions, Senior --- Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack. 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