TYPO3 uses PHP namespaces for all classes in the Core.

The general structure of namespaces is the following:

General namespace schema

For the Core, the vendor name is TYPO3\CMS and the package name corresponds to a system extension.

All classes must be located inside the Classes folder at the root of the (system) extension. The category name may contain several segments that correspond to the path inside the Classes folder.

Finally the class name is the same as the corresponding file name, without the .php extension.

"UpperCamelCase" is used for all segments.

Core example

The good old t3lib_div class has been renamed to: \TYPO3\CMS\Core\Utility\GeneralUtility

This means that the class is now found in the core system extension, in folder Classes/Utility, in a file named GeneralUtility.php.

Usage in extensions

Extension developers are free to use their own vendor name. Important: It may consist of one segment only. Vendor names must start with an uppercase character and are usually written in UpperCamelCase style. In order to avoid problems with different filesystems, only the characters a-z, A-Z, 0-9 and the dash sign "-" are allowed for package names – don't use special characters:

Examples for vendor names
// correct vendor name for 'web company':

// wrong vendor name for 'web company':

The package name corresponds to the extension key. Underscores in the extension key are removed in the namespace and replaced by upper camel-case. So extension key:

Do not do this

would become:

Do not do this

in the namespace.

As mentioned above, all classes must be located in the Classes folder inside your extension. All sub-folders translate to a segment of the category name and the class name is the file name without the .php extension.

Looking at the "examples" extension, file examples/Classes/Controller/DefaultController.php

corresponds to the class with \Documentation\Examples\Controller\DefaultController as fully qualified name.

Inside the class, the namespace is declared as:

namespace Documentation\Examples\Controller;

Namespaces in Extbase

When registering components in Extbase, the "UpperCamelCase" notation of the extension key is used.

For a backend module:

use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

    // ...

For a frontend module:

use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

    // ...

Namespaces for test classes

As for ordinary classes, namespaces for test classes start with a vendor name followed by the extension key.

All test classes reside in a Tests folder and thus the third segment of the namespace must be "Tests". Unit tests are located in a Unit folder which is the fourth segment of the namespace. Any further subfolders will be subsequent segments.

So a test class in EXT:foo_bar_baz/Tests/Unit/Bla/ will have as namespace \MyVendor\FooBarBaz\Tests\Unit\Bla.

Creating Instances

The following example shows how you can create instances by means of GeneralUtility::makeInstance():

use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Frontend\ContentObject\ContentObjectRenderer;

$contentObject = GeneralUtility::makeInstance(ContentObjectRenderer::class);

include and required

There is no need for require() or include() statements. All classes adhering to namespace conventions will automatically be located and included by the autoloader.


For more information about PHP namespaces in general, you may want to refer to the PHP documentation and in particular the Namespaces FAQ.