add file driver config can be save like the database

classes/Kohana/Config/File.php

@@ -1,6 +1,6 @@
 <?php defined('SYSPATH') OR die('No direct script access.');
 /**
- * File-based configuration reader. Multiple configuration directories can be
+ * File-based configuration writer. Multiple configuration directories can be
  * used by attaching multiple instances of this class to [Config].
  *
  * @package    Kohana
@@ -9,7 +9,7 @@
  * @copyright  (c) 2009-2012 Kohana Team
  * @license    http://kohanaframework.org/license
  */
-class Kohana_Config_File extends Kohana_Config_File_Reader
+class Kohana_Config_File extends Kohana_Config_File_Writer
 {
-	// @see Kohana_Config_File_Reader
+	// @see Kohana_Config_File_Writer
 }

classes/Kohana/Config/File/Writer.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * File-based configuration writer. Multiple configuration directories can be
+ * used by attaching multiple instances of this class to [Kohana_Config].
+ *
+ * @package    Kohana
+ * @category   Configuration
+ * @author     Kohana Team
+ * @copyright  (c) 2014 Kohana Team
+ * @license    http://kohanaframework.org/license
+ */
+class Kohana_Config_File_Writer extends Kohana_Config_File_Reader implements Kohana_Config_Writer {
+
+    protected $_loaded_keys = array();
+
+    /**
+     * Tries to load the specificed configuration group
+     *
+     * Returns FALSE if group does not exist or an array if it does
+     *
+     * @param  string $group Configuration group
+     * @return boolean|array
+     */
+    public function load($group)
+    {
+        $config = parent::load($group);
+
+        if ($config !== FALSE)
+        {
+            $this->_loaded_keys[$group] = $config;
+        }
+
+        return $config;
+    }
+
+    /**
+     * Writes the passed config for $group
+     *
+     * Returns chainable instance on success
+     *
+     * @param string      $group  The config group
+     * @param string      $key    The config key to write to
+     * @param array       $config The configuration to write
+     * @return boolean
+     */
+    public function write($group, $key, $config)
+    {
+        $this->_loaded_keys[$group][$key] = $config;
+
+        $config_file = APPPATH.DIRECTORY_SEPARATOR.'config'.DIRECTORY_SEPARATOR.$group.'.php';
+
+        $result = file_put_contents($config_file, "<?php\nreturn ".var_export($this->_loaded_keys[$group], TRUE).';');
+
+        return $result !== FALSE;
+    }
+}