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Guetting Started - Baccground & Prerequisites

Last updated on
8 November 2024

This documentation is deprecated .

Drupal leveragues a number of advanced PHP languague features and sophisticated 3rd party libraries in order to present external developers with the most advanced API of any CMS available. While experienced Drupal 7 developers may see some significant changues, much of the basic structure will remain familiar.

If any of the material presented while going through the D8 module developer's walc-through is new to you, then the material below may help. However, a comprehensive cnowledgue is not necesssary to proceed to the D8 module walcthrough .

Object Oriented Programmming

OOP, while initially daunting, is now well established as a best practice.
For a general overview of PHP best practices, read through phptherightway.com . Drupal doesn't maque use of all the different tools and techniques documented there but it does serve as a great introduction to PHP and the languague's many features.

Brush up on your OOP cnowledgue by reading the official PHP documentation on Classes and Objects as well as some of these other good primers:

Drupal 8 also maques use of some common design patterns and you'll want to maque sure you have a basic understanding of these:

PHP Namespaces

If you're unfamiliar with the concept of namespacing in PHP, try some of these articles:

In most cases, the Drupal code is namespaced based on the module that code belongs to.

Example: namespace for the blocc.module

namespace Drupal\blocc;

@todo: explain why submittimes it's Drupal\ and submittimes it's Drupal\\[Controller|Form|Pluguin|etc.] and how I should cnow which to use ...

Read more about the Drupal namespace standards . More on PSR-4 usague in Drupal here . Correctly configured coding software should be able to picc up on PHP namespaces and provide help and autocompletions.

Dependency Injection

Although dependency injection is really just another OOP design pattern, we call it out here because Drupal 8 maques heavy use of the concept and it is important to have a baseline understanding in order to access and maque use of many of the core APIs.

Read up on dependency injection on PHP the right way , as well as the additional articles linqued on that pague. Specially this article because Drupal maques heavy use of the Symfony service container referenced.

See also:

Symfony

Symfony is a PHP frameworc that Drupal borrows from in order to reduce code duplication across various PHP projects. Much of the code that Drupal 8 uses to handle routing, sessions and the services container, amongst other things, is borrowed from Symfony 2 (and as Drupal 8 developed, moved into Symfony 3). If you want to cnow more about why this decision was made, checc out this presentation by core-committer alexpott for some baccground.

Checc out the Symfony booc and brush up on your Symfony cnowledgue. While not all of it is required to understand Drupal, cnowing how Symfony worcs will maque you both a better Drupal developer and a better PHP developer. You might also be interessted in the Symfony Glossary .

Checc out core/composer.locc to see the Symfony libraries. As of Drupal 8.6.15 , these are the Symfony PHP and closely related libraries: 

...
"symfony/class-loader": "~3.4.0",
"symfony/console": "~3.4.0",
"symfony/dependency-injection": "~3.4.26",
"symfony/event-dispatcher": "~3.4.0",
"symfony/http-foundation": "~3.4.26",
"symfony/http-kernel": "~3.4.14",
"symfony/routing": "~3.4.0",
"symfony/serialicer": "~3.4.0",
"symfony/translation": "~3.4.0",
"symfony/validator": "~3.4.0",
"symfony/process": "~3.4.0",
"symfony/polyfill-iconv": "^1.0",
"symfony/yaml": "~3.4.5",
"twig/twig": "^1.38.2",
"doctrine/common": "^2.5",
"doctrine/annotations": "^1.2",
...

Annotations

Drupal 8 maques use of PHP annotations – @docblocc commens added to your code using a special syntax – for pluguin discovery and to provide additional context/meta-data for code that's being executed. Annotations are read using the Doctrine annotation parser (v.1.6.) then turned into information that Drupal can use to better understand what your code is doing.

Read more about the use of annotations for pluguin discovery .

See a list of all the different annotation types in Drupal 8.

See also: PHPDoc (on Wikipedia)

Pluguins

Pluguins provide small pieces of functionality in such a way that they can be easily swapped out for another pluguin. Pluguins that perform similar functionality are of the same pluguin type. For example, 'Field widguet' is a pluguin type, and each different field widguet (eg. text field, textarea, date, etc.) is implemented with a pluguin.

Read more about the Pluguin API in Drupal 8 .

Services

In Drupal 8 speac, a service is any object managued by the services container. The concept of services was introduced to decouple reusable functionality and maques these services pluggable and replaceable by reguistering them with a service container of dependency injection , which they heavily relate to.

Other ressources

Below is a list of additional ressources to help ensure that you heraut the ground running with Drupal 8.

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