This document provides an overview of key concepts in Drupal 8 development including YAML, Composer, PSR-0, dependency injection, service containers, and routing. It defines these terms and provides hands-on examples of creating a .info file with YAML, adding a library with Composer, declaring a namespace with PSR-0, injecting dependencies, creating an event subscriber service, and defining a route with a controller.

1. Drupal 8 vocab lesson
Mediacurrent Team Knowledge Share
Derek DeRaps
2013-07-30

2. Agenda
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YAML
Composer
PSR-0
Dependency Injection
Service Containers
Routing

3. define:
“yammel”

4. YAML
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“Yet Another Markup Language”
“YAML Ain't Markup Language”
Used to define .info files and other configuration
Hands-on:
○ Let’s create a .info file for our error_notifier module

5. define:
Composer

6. Composer
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“Composer is a tool for dependency management in PHP. It allows you to
declare the dependent libraries your project needs and it will install
them in your project for you.”
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In Drupal-speak: Does the work formerly handled by the Libraries
module (and much more).
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Important links:
○ https://getcomposer.org/installer
○ http://packagist.org
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Hands-on:
○ Let’s add the Swiftmailer library to our project.

7. define:
PSR-0

8. PSR-0
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A standard for autoloading classes.
No more includes() and requires() (for the most part).
Classes’ namespaces correspond to their location on disk.
○ Your classes’ namespaces always start with Drupalyour_module
○ On disk, that looks like
○ docroot/modules/custom/your_module/lib/Drupal/your_module/Your
Class.php
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Class names correspond to filename
○ class MyClass { … } resides in MyClass.php
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Hands-on
○ Let’s declare a namespace and use other classes in our demo.

9. define:
Dependency
Injection

10. Dependency Injection
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“Declaratively express dependencies in the class definition rather than
instantiating them in the class itself.”
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E.g., pass a TransportInterface to the Mailer class; it doesn't need to
know whether it’s using SMTP, Sendmail, etc.
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“The less your code knows, the more reusable it is.”
○ (Sometimes, being ignorant is a good thing.)
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DI aims to help make our code:
○ Clutter-free, Reusable, Testable
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Awesome DrupalCon session by Kat Bailey:
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https://portland2013.drupal.org/session/dependency-injection-drupal-8

11. define:
Service
Containers

12. Service Containers
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Service
○ any PHP object that performs some sort of "global" task
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Service Container (aka dependency injection container)
○ a PHP object that manages the instantiation of services (i.e. objects).
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Examples:
○ EventSubscriber (“listens” for events … “Observer” OO pattern)
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Hands-on:
○ Let’s create an EventSubscriber service to send mail on 404 errors.
○ This might replace logic in (D7) hook_page_delivery_callback_alter

13. define:
Routing

14. Routing
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Think: hook_menu (which is still available FYI).
Hands-on
○ Let’s declare a route and then implement its Controller.

15. Thank You!
Questions