File structure¶

TYPO3 files use the following structure:

Opening PHP tag (including strict_types declaration)
Namespace
Copyright notice
Included files
Class information block in phpDoc format
PHP class
Optional module execution code

The following sections discuss each of these parts.

Namespace¶

The namespace declaration of each PHP file in the TYPO3 Core shows where the file belongs inside TYPO3 CMS. The namespace starts with "TYPO3\CMS\", then the extension name in UpperCamelCase, a backslash and then the name of the subfolder of Classes/, in which the file is located (if any). E.g. the file typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php with the class ContentObjectRenderer is in the namespace "TYPO3\CMS\Frontend\ContentObject".

use statements can be added to this section.

Copyright notice¶

TYPO3 is released under the terms of GNU General Public License version 2 or any later version. The copyright notice with a reference to the license text must be included at the top of every TYPO3 PHP class file. user files must have this copyright notice as well. Example:

<?php
declare(strict_types=1);
namespace TYPO3\CMS\XXX;

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

The wording must not be changed/updated/extended, under any circumstances.

Included files¶

Files are included using the require_once() function. All TYPO3 files must use absolute paths in calls to require_once(). There are two ways to obtain the path to the included file:

Use one of the predefined TYPO3 constants: PATH_typo3 or PATH_site. The first one contains the absolute path to the corresponding TYPO3 directory. The last constant contains the absolute path to the TYPO3 root directory. Example:
```
require_once(PATH_typo3 . 'sysext/frontend/Classes/Plugin/AbstractPlugin.php');
```
Use the ExtensionManagementUtility::extPath() function. This function accepts two arguments: first the extension key and second the path to the included file inside the extension. The second argument is optional but recommended to use. Examples:
```
require_once(ExtensionManagementUtility::extPath('lang', 'Classes/LanguageService.php'));
require_once(ExtensionManagementUtility::extPath('lang') . 'Classes/LanguageService.php');
```

Always use one of these two ways to include files. This is required to include files even from the current directory. Some installations do not have the current directory in the PHP include path and require_once() without a proper path will result in a fatal PHP error.

Class information block¶

The class information block provides basic information about the class in the file. It should include a description of the class. Example:

/**
 * This class provides XYZ plugin implementation.
 */

PHP class¶

The PHP class follows the class information block. PHP code must be formatted as described in chapter "PHP syntax formatting".

The class name is expected to follow some conventions. It must be identical to the file name and must be written in upper camel case.

Taking again the example of file typo3/sysext/core/Classes/Cache/Backend/AbstractBackend.php, the PHP class declaration will look like:

class AbstractBackend implements \TYPO3\CMS\Core\Cache\Backend\BackendInterface
{
        …
}

Optional module execution code¶

Module execution code instantiates the class and runs its method(s). Typically this code can be found in eID scripts and old Backend modules. Here is how it may look like:

$controller = GeneralUtility::makeInstance(\Vendor\MyNamespace\MyExtension\Controller\AjaxController::class);
$controller->main();

This code must appear after the PHP class.