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