merged branch schmittjoh/configurableExtension (PR symfony#3632)

Commits
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3f2b917 added a configurable extension base class

Discussion
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added a configurable extension base class

This is mostly a convenience class which provides first-class integration with the Config/Definition component.

src/Symfony/Component/HttpKernel/DependencyInjection/ConfigurableExtension.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of the Symfony framework.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Symfony\Component\HttpKernel\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * This extension sub-class provides first-class integration with the
+ * Config/Definition Component.
+ *
+ * You can use this as base class if you
+ *
+ *    a) use the Config/Definition component for configuration
+ *    b) your configuration class is named "Configuration" and
+ *    c) the configuration class resides in the DependencyInjection sub-folder
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+abstract class ConfigurableExtension extends Extension
+{
+    /**
+     * {@inheritDoc}
+     */
+    public final function load(array $configs, ContainerBuilder $container)
+    {
+        $this->loadInternal($this->processConfiguration($this->getConfiguration(array(), $container), $configs), $container);
+    }
+
+    /**
+     * Configures the passed container according to the merged configuration.
+     *
+     * @param array $mergedConfig
+     * @param ContainerBuilder $container
+     */
+    abstract protected function loadInternal(array $mergedConfig, ContainerBuilder $container);
+}