--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection;
+
+/**
+ * Parameter represents a parameter reference.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class Parameter
+{
+ private $id;
+
+ /**
+ * @param string $id The parameter key
+ */
+ public function __construct($id)
+ {
+ $this->id = $id;
+ }
+
+ /**
+ * @return string The parameter key
+ */
+ public function __toString()
+ {
+ return (string) $this->id;
+ }
+}