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backend/vendor/doctrine/collections/docs/en/derived-collections.rst

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+Derived Collections
+===================
+
+You can create custom collection classes by extending the
+``Doctrine\Common\Collections\ArrayCollection`` class. If the
+``__construct`` semantics are different from the default ``ArrayCollection``
+you can override the ``createFrom`` method:
+
+.. code-block:: php
+    final class DerivedArrayCollection extends ArrayCollection
+    {
+        /** @var \stdClass */
+        private $foo;
+
+        public function __construct(\stdClass $foo, array $elements = [])
+        {
+            $this->foo = $foo;
+
+            parent::__construct($elements);
+        }
+
+        protected function createFrom(array $elements) : self
+        {
+            return new static($this->foo, $elements);
+        }
+    }