use trait

app/code/core/Mage/Adminhtml/Block/Catalog/Helper/Form/Wysiwyg.php

@@ -21,6 +21,8 @@
  */
 class Mage_Adminhtml_Block_Catalog_Helper_Form_Wysiwyg extends Varien_Data_Form_Element_Textarea
 {
+    use Mage_Core_Trait_Module;
+
     /**
      * Retrieve additional html and put it at the end of element html
      *
@@ -50,7 +52,7 @@ public function getAfterElementHtml()
      */
     public function getIsWysiwygEnabled()
     {
-        if (Mage::helper('catalog')->isModuleEnabled('Mage_Cms')) {
+        if ($this->isModuleEnabled('Mage_Cms', 'catalog')) {
             return (bool)(Mage::getSingleton('cms/wysiwyg_config')->isEnabled()
                 && $this->getEntityAttribute()->getIsWysiwygEnabled());
         }

app/code/core/Mage/Adminhtml/controllers/System/ConfigController.php

@@ -106,7 +106,7 @@ public function editAction()
             $block = $this->getLayout()->createBlock('adminhtml/system_config_edit');
             $this->_addContent($block->initForm());
 
-            if (($current == 'carriers') && Mage::helper('core')->isModuleEnabled('Mage_Usa')) {
+            if (($current == 'carriers') && $this->isModuleEnabled('Mage_Usa')) {
                 $this->_addJs($this->getLayout()
                      ->createBlock('adminhtml/template')
                      ->setTemplate('system/shipping/ups.phtml'));

app/code/core/Mage/Api2/Model/Resource/Validator.php

@@ -28,6 +28,8 @@
  */
 abstract class Mage_Api2_Model_Resource_Validator
 {
+    use Mage_Core_Trait_Module;
+
     /**
      * Array of validation failure errors.
      *

app/code/core/Mage/Catalog/Model/Api2/Product/Validator/Product.php

@@ -380,7 +380,7 @@ protected function _validateStockData($data)
                 if (isset($stockData['enable_qty_increments']) && (bool) $stockData['enable_qty_increments'] == true) {
                     $this->_validatePositiveNumeric($stockData, $fieldSet, 'qty_increments', false, true);
                 }
-                if (Mage::helper('catalog')->isModuleEnabled('Mage_CatalogInventory')) {
+                if ($this->isModuleEnabled('Mage_CatalogInventory', 'catalog')) {
                     $this->_validateSource(
                         $stockData,
                         $fieldSet,

app/code/core/Mage/Core/Block/Abstract.php

@@ -1580,7 +1580,7 @@ protected function _isSecure()
 
     public function isModuleEnabled(?string $moduleName = null, string $helperAlias = 'core'): bool
     {
-        if ($moduleName === null) {
+        if (is_null($moduleName)) {
             $moduleName = $this->getModuleName();
         }
 
@@ -1595,7 +1595,7 @@ public function isModuleEnabled(?string $moduleName = null, string $helperAlias
      */
     public function isModuleOutputEnabled(?string $moduleName = null, string $helperAlias = 'core'): bool
     {
-        if ($moduleName === null) {
+        if (is_null($moduleName)) {
             $moduleName = $this->getModuleName();
         }
 

app/code/core/Mage/Core/Controller/Varien/Action.php

@@ -23,6 +23,8 @@
  */
 abstract class Mage_Core_Controller_Varien_Action
 {
+    use Mage_Core_Trait_Module;
+
     public const FLAG_NO_CHECK_INSTALLATION    = 'no-install-check';
     public const FLAG_NO_DISPATCH              = 'no-dispatch';
     public const FLAG_NO_PRE_DISPATCH          = 'no-preDispatch';

app/code/core/Mage/Core/Helper/Abstract.php

@@ -129,7 +129,7 @@ protected function _getModuleName()
      */
     public function isModuleOutputEnabled($moduleName = null)
     {
-        if ($moduleName === null) {
+        if (is_null($moduleName)) {
             $moduleName = $this->_getModuleName();
         }
 
@@ -148,7 +148,7 @@ public function isModuleOutputEnabled($moduleName = null)
      */
     public function isModuleEnabled($moduleName = null)
     {
-        if ($moduleName === null) {
+        if (is_null($moduleName)) {
             $moduleName = $this->_getModuleName();
         }
 

app/code/core/Mage/Core/Model/Abstract.php

@@ -29,6 +29,8 @@
  */
 abstract class Mage_Core_Model_Abstract extends Varien_Object
 {
+    use Mage_Core_Trait_Module;
+
     /**
      * Prefix of model events names
      *
@@ -635,9 +637,4 @@ protected function _clearData()
     {
         return $this;
     }
-
-    public function isModuleEnabled(string $moduleName, string $helperAlias = 'core'): bool
-    {
-        return Mage::helper($helperAlias)->isModuleEnabled($moduleName);
-    }
 }

app/code/core/Mage/Core/Model/Resource/Abstract.php

@@ -21,6 +21,8 @@
  */
 abstract class Mage_Core_Model_Resource_Abstract
 {
+    use Mage_Core_Trait_Module;
+
     /**
      * Main constructor
      */
@@ -226,9 +228,4 @@ protected function _prepareTableValueForSave($value, $type)
         }
         return $value;
     }
-
-    public function isModuleEnabled(string $moduleName, string $helperAlias = 'core'): bool
-    {
-        return Mage::helper($helperAlias)->isModuleEnabled($moduleName);
-    }
 }

app/code/core/Mage/Core/Trait/Module.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * OpenMage
+ *
+ * This source file is subject to the Open Software License (OSL 3.0)
+ * that is bundled with this package in the file LICENSE.txt.
+ * It is also available at https://opensource.org/license/osl-3-0-php
+ *
+ * @category   Mage
+ * @package    Mage_Core
+ * @copyright  Copyright (c) 2006-2020 Magento, Inc. (https://www.magento.com)
+ * @copyright  Copyright (c) 2020-2023 The OpenMage Contributors (https://www.openmage.org)
+ * @license    https://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+ */
+
+declare(strict_types=1);
+
+/**
+ * Module trait
+ *
+ * @category   Mage
+ * @package    Mage_Core
+ */
+trait Mage_Core_Trait_Module
+{
+    /**
+     * @uses Mage_Core_Helper_Abstract::isModuleEnabled()
+     */
+    public function isModuleEnabled(?string $moduleName, string $helperAlias = 'core'): bool
+    {
+        return Mage::helper($helperAlias)->isModuleEnabled($moduleName);
+    }
+}

app/code/core/Mage/Eav/Model/Entity/Collection/Abstract.php

@@ -21,6 +21,8 @@
  */
 abstract class Mage_Eav_Model_Entity_Collection_Abstract extends Varien_Data_Collection_Db
 {
+    use Mage_Core_Trait_Module;
+
     /**
      * Array of items with item id key
      *
@@ -1524,9 +1526,4 @@ public function _prepareSelect(Varien_Db_Select $select)
 
         return (string)$select;
     }
-
-    public function isModuleEnabled(string $moduleName, string $helperAlias = 'core'): bool
-    {
-        return Mage::helper($helperAlias)->isModuleEnabled($moduleName);
-    }
 }