add chapter about data repositories, and start work on perfomance chapter

implementation/15-adding-content/src/Factory/DoctrineEm.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types=1);
+
+namespace Lubian\NoFramework\Factory;
+
+use Doctrine\ORM\EntityManager;
+use Doctrine\ORM\EntityManagerInterface;
+use Doctrine\ORM\Mapping\Driver\AttributeDriver;
+use Doctrine\ORM\Tools\Setup;
+use Lubian\NoFramework\Settings;
+
+final class DoctrineEm
+{
+    public function __construct(private Settings $settings)
+    {
+    }
+
+    public function create(): EntityManagerInterface
+    {
+        $config = Setup::createConfiguration($this->settings->doctrine['devMode']);
+
+        $config->setMetadataDriverImpl(
+            new AttributeDriver(
+                $this->settings->doctrine['metadataDirs']
+            )
+        );
+
+        return EntityManager::create(
+            $this->settings->connection,
+            $config,
+        );
+    }
+}