TYPO3 v15 dev-main snapshot ()

2026-08-10 22:31:09 +02:00
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+.. include:: /Includes.rst.txt
+
+.. _feature-67293:
+
+=============================================
+Feature: #67293 - Dependency ordering service
+=============================================
+
+See :issue:`67293`
+
+Description
+===========
+
+In many cases it is necessary to establish a sorted list of items from a set of "dependencies".
+The ordered list is then used to execute actions in the given order.
+
+Some examples from the Core are:
+
+- Hook execution order
+- Extension loading order
+- Listing of menu items
+
+The dependencies are therefore specified in a relative manner, outlining that an item has to be executed/loaded/listed
+"before" or "after" some other item.
+
+Typical use case:
+
+.. code-block:: php
+
+	$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['someExt']['someHook'][<some id>] = [
+		'handler' => someClass::class,
+		'runBefore' => [ <some other ID> ],
+		'runAfter' => [ ... ],
+		...
+	];
+
+In order to evaluate such relative dependencies to finally have a sorted list for `['someHook']`, we introduced a new
+helper class `\TYPO3\CMS\Core\Service\DependencyOrderingService`, which does the evaluation work for you.
+
+Example usage:
+
+.. code-block:: php
+
+	$hooks = $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['someExt']['someHook'];
+	$sortedHooks = GeneralUtility:makeInstance(DependencyOrderingService::class)->orderByDependencies($hooks , 'runBefore', 'runAfter');
+
+`$sortedHooks` will then contain the content of `$hooks`, but sorted according to the dependencies.
+
+The `DependencyOrderingService` class also detects cycles in the dependencies and will throw an Exception in case
+conflicting dependencies have been defined.
+
+In case the initial list does not specify a dependency for an item, those items will be put last in the final sorted list.
+
+
+.. index:: PHP-API