[TASK] Deprecate StandaloneView getters

Views should be data sinks, but not data sources:
In Fluid, RenderingContext is the main state object
used to carry rendering related state.

As such, StandaloneView should not provide getter
methods to retrieve state after it has been set:
They could be misused to "park" state, which is
a sign of bad architecture since only controllers
should keep track, carry and update such state.

The patch deprecates offending methods in
StandaloveView.

Change-Id: Id5c5fc2826b23c258b0f94aedbb0c5e75904e2db
Resolves: #98371
Releases: main
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75773
Tested-by: core-ci <typo3@b13.com>
Tested-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>

typo3/sysext/core/Documentation/Changelog/12.0/Deprecation-98371-DeprecatedFluidGetters.rst

@@ -0,0 +1,54 @@
+.. include:: /Includes.rst.txt
+
+.. _deprecation-98371-1663524265:
+
+==============================================
+Deprecation: #98371 - Deprecated Fluid getters
+==============================================
+
+See :issue:`98371`
+
+Description
+===========
+
+Views in a Model-View-Controller (MVC) construct should be data sinks.
+Class :php:`\TYPO3\CMS\Fluid\View\StandaloneView` violates this concept by
+providing some :php:`getXY()` methods that allow fetching previously set state.
+
+The Fluid class :php:`\TYPO3\CMS\Fluid\Core\Rendering\RenderingContext`
+is the main object carried around within the rendering chain to keep track
+of state. It is the main data object used in view helpers.
+
+As such, :php:`StandaloneView` should not allow fetching state since it allows
+to be misused to park state, which is primarily a controller concern instead.
+
+To enforce this pattern, the following methods have been marked as deprecated in
+TYPO3 core v12 and will be removed in v13:
+
+* :php:`\TYPO3\CMS\Fluid\View\StandaloneView->getRequest()`
+* :php:`\TYPO3\CMS\Fluid\View\StandaloneView->getFormat()`
+* :php:`\TYPO3\CMS\Fluid\View\StandaloneView->getTemplatePathAndFilename()`
+
+
+Impact
+======
+
+Calling one of the above methods triggers a PHP :php:`E_USER_DEPRECATED` level
+error.
+
+
+Affected installations
+======================
+
+Instances with extensions using one of the above methods.
+
+
+Migration
+=========
+
+Do not misuse :php:`StandaloneView` as data source. Typically, controllers
+should handle and keep track of state like a PSR-7 Request and set or update
+view state.
+
+
+.. index:: Fluid, NotScanned, ext:fluid

typo3/sysext/fluid/Classes/View/StandaloneView.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -43,10 +45,9 @@ public function __construct()
     /**
      * Sets the format of the current request (default format is "html")
      *
-     * @param string $format
      * @throws \RuntimeException
      */
-    public function setFormat($format)
+    public function setFormat(string $format): void
     {
         if (!$this->baseRenderingContext instanceof RenderingContext) {
             throw new \RuntimeException('The rendering context must be of type ' . RenderingContext::class, 1482251886);
@@ -64,10 +65,14 @@ public function setFormat($format)
      *
      * @return string $format
      * @throws \RuntimeException
-     * @todo: deprecate?!
+     * @deprecated since v12, will be removed in v13: Views should be data sinks, not data sources. No substitution.
      */
     public function getFormat()
     {
+        trigger_error(
+            'Method ' . __METHOD__ . ' has been deprecated in v12 and will be removed with v13. Do not use StandaloneView as data source.',
+            E_USER_DEPRECATED
+        );
         if ($this->baseRenderingContext instanceof RenderingContext) {
             return $this->baseRenderingContext->getRequest()->getFormat();
         }
@@ -89,10 +94,14 @@ public function setRequest(?ServerRequestInterface $request = null): void
      *
      * @throws \RuntimeException
      * @internal
-     * @todo: deprecate?!
+     * @deprecated since v12, will be removed in v13: Views should be data sinks, not data sources. No substitution.
      */
     public function getRequest(): ?ServerRequestInterface
     {
+        trigger_error(
+            'Method ' . __METHOD__ . ' has been deprecated in v12 and will be removed with v13. Do not use StandaloneView as data source.',
+            E_USER_DEPRECATED
+        );
         if ($this->baseRenderingContext instanceof RenderingContext) {
             return $this->baseRenderingContext->getRequest();
         }
@@ -107,9 +116,14 @@ public function getRequest(): ?ServerRequestInterface
      * and return that template path and filename directly, instead of attempting to resolve it.
      *
      * @return string Fluid template path
+     * @deprecated since v12, will be removed in v13: Views should be data sinks, not data sources. No substitution.
      */
     public function getTemplatePathAndFilename()
     {
+        trigger_error(
+            'Method ' . __METHOD__ . ' has been deprecated in v12 and will be removed with v13. Do not use StandaloneView as data source.',
+            E_USER_DEPRECATED
+        );
         $templatePaths = $this->baseRenderingContext->getTemplatePaths();
         return $templatePaths->resolveTemplateFileForControllerAndActionAndFormat(
             $this->baseRenderingContext->getControllerName(),
@@ -119,30 +133,26 @@ public function getTemplatePathAndFilename()
     }
 
     /**
-     * Sets the Fluid template source
+     * Sets a Fluid template source string directly.
      * You can use setTemplatePathAndFilename() alternatively if you only want to specify the template path
-     *
-     * @param string $templateSource Fluid template source code
      */
-    public function setTemplateSource($templateSource)
+    public function setTemplateSource(string $templateSource): void
     {
         $this->baseRenderingContext->getTemplatePaths()->setTemplateSource($templateSource);
     }
 
     /**
      * Checks whether a template can be resolved for the current request
-     *
-     * @return bool
      */
-    public function hasTemplate()
+    public function hasTemplate(): bool
     {
         try {
             $this->baseRenderingContext->getTemplatePaths()->getTemplateSource(
                 $this->baseRenderingContext->getControllerName(),
                 $this->baseRenderingContext->getControllerAction()
             );
             return true;
-        } catch (InvalidTemplateResourceException $e) {
+        } catch (InvalidTemplateResourceException $_) {
             return false;
         }
     }