..  include:: /Includes.rst.txt
..  index:: Events; EvaluateModifierFunctionEvent
..  _EvaluateModifierFunctionEvent:

=============================
EvaluateModifierFunctionEvent
=============================

..  versionadded:: 12.0
    This event is a substitution of the
    :php:`$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tsparser.php']['preParseFunc']`
    hook.

The PSR-14 event
:php:`\TYPO3\CMS\Core\TypoScript\AST\Event\EvaluateModifierFunctionEvent`
allows custom TypoScript functions using the :typoscript:`:=` operator.


Example
=======

A simple TypoScript example looks like this:

..  code-block:: typoscript
    :caption: EXT:my_extension/Configuration/TypoScript/setup.typoscript

    someIdentifier = originalValue
    someIdentifier := myModifierFunction(myFunctionArgument)

The corresponding event listener class could look like this:

..  literalinclude:: _EvaluateModifierFunctionEvent/_MyEventListener.php
    :language: php
    :caption: EXT:my_extension/Classes/TypoScript/EventListener/MyEventListener.php

..  include:: /_includes/EventsAttributeAdded.rst.txt

API
===

..  include:: /CodeSnippets/Events/Core/EvaluateModifierFunctionEvent.rst.txt