Move a trait into a helper class.

We thought traits were pretty cool and they are. But they result in
harder to read/understand code that I'd prefer to not have long term.

src/ORM/Association/DependentDeleteHelper.php

@@ -0,0 +1,59 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         3.0.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\ORM\Association;
+
+use Cake\Datasource\EntityInterface;
+use Cake\ORM\Association;
+
+/**
+ * Helper class for cascading deletes in associations.
+ *
+ * @internal
+ */
+class DependentDeleteHelper
+{
+
+    /**
+     * Cascade a delete to remove dependent records.
+     *
+     * This method does nothing if the association is not dependent.
+     *
+     * @param \Cake\ORM\Association $association The association callbacks are being cascaded on.
+     * @param \Cake\Datasource\EntityInterface $entity The entity that started the cascaded delete.
+     * @param array $options The options for the original delete.
+     * @return bool Success.
+     */
+    public function cascadeDelete(Association $association, EntityInterface $entity, array $options = [])
+    {
+        if (!$association->getDependent()) {
+            return true;
+        }
+        $table = $association->getTarget();
+        $foreignKey = (array)$association->getForeignKey();
+        $bindingKey = (array)$association->getBindingKey();
+        $conditions = array_combine($foreignKey, $entity->extract($bindingKey));
+
+        if ($association->getCascadeCallbacks()) {
+            foreach ($association->find()->where($conditions)->toList() as $related) {
+                $table->delete($related, $options);
+            }
+
+            return true;
+        }
+        $conditions = array_merge($conditions, $association->getConditions());
+
+        return (bool)$table->deleteAll($conditions);
+    }
+}

src/ORM/Association/DependentDeleteTrait.php

@@ -15,11 +15,14 @@
 namespace Cake\ORM\Association;
 
 use Cake\Datasource\EntityInterface;
+use Cake\ORM\Association\DependentDeleteHelper;
 
 /**
  * Implements cascading deletes for dependent associations.
  *
  * Included by HasOne and HasMany association classes.
+ *
+ * @deprected 3.5.0 Unused in CakePHP now. This class will be removed in 4.0.0
  */
 trait DependentDeleteTrait
 {
@@ -35,24 +38,7 @@ trait DependentDeleteTrait
      */
     public function cascadeDelete(EntityInterface $entity, array $options = [])
     {
-        if (!$this->getDependent()) {
-            return true;
-        }
-        $table = $this->getTarget();
-        $foreignKey = (array)$this->getForeignKey();
-        $bindingKey = (array)$this->getBindingKey();
-        $conditions = array_combine($foreignKey, $entity->extract($bindingKey));
-
-        if ($this->_cascadeCallbacks) {
-            foreach ($this->find()->where($conditions)->toList() as $related) {
-                $table->delete($related, $options);
-            }
-
-            return true;
-        }
-
-        $conditions = array_merge($conditions, $this->getConditions());
-
-        return $table->deleteAll($conditions);
+        $helper = new DependentDeleteHelper();
+        return $helper->cascadeDelete($this, $entity, $options);
     }
 }

src/ORM/Association/HasMany.php

@@ -20,6 +20,7 @@
 use Cake\Database\Expression\QueryExpression;
 use Cake\Datasource\EntityInterface;
 use Cake\ORM\Association;
+use Cake\ORM\Association\DependentDeleteHelper;
 use Cake\ORM\Association\Loader\SelectLoader;
 use Cake\ORM\Table;
 use InvalidArgumentException;
@@ -34,8 +35,6 @@
 class HasMany extends Association
 {
 
-    use DependentDeleteTrait;
-
     /**
      * Order in which target records should be returned
      *
@@ -655,4 +654,13 @@ public function eagerLoader(array $options)
 
         return $loader->buildEagerLoader($options);
     }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function cascadeDelete(EntityInterface $entity, array $options = [])
+    {
+        $helper = new DependentDeleteHelper();
+        return $helper->cascadeDelete($this, $entity, $options);
+    }
 }

src/ORM/Association/HasOne.php

@@ -16,6 +16,7 @@
 
 use Cake\Datasource\EntityInterface;
 use Cake\ORM\Association;
+use Cake\ORM\Association\DependentDeleteHelper;
 use Cake\ORM\Association\Loader\SelectLoader;
 use Cake\ORM\Table;
 use Cake\Utility\Inflector;
@@ -28,9 +29,6 @@
  */
 class HasOne extends Association
 {
-
-    use DependentDeleteTrait;
-
     /**
      * Valid strategies for this type of association
      *
@@ -145,4 +143,13 @@ public function eagerLoader(array $options)
 
         return $loader->buildEagerLoader($options);
     }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function cascadeDelete(EntityInterface $entity, array $options = [])
+    {
+        $helper = new DependentDeleteHelper();
+        return $helper->cascadeDelete($this, $entity, $options);
+    }
 }