merge configs instead of overriding them completely

cake/libs/configure.php

@@ -286,14 +286,25 @@ public static function drop($name) {
  * @link http://book.cakephp.org/view/929/load
  * @param string $key name of configuration resource to load.
  * @param string $config Name of the configured reader to use to read the resource identfied by $key.
+ * @param boolean $merge if config files should be merged instead of simply overridden
  * @return mixed false if file not found, void if load successful.
  * @throws ConfigureException Will throw any exceptions the reader raises.
  */
-	public static function load($key, $config = 'default') {
+	public static function load($key, $config = 'default', $merge = false) {
 		if (!isset(self::$_readers[$config])) {
 			return false;
 		}
 		$values = self::$_readers[$config]->read($key);
+
+		if ($merge) {
+			$keys = array_keys($values);
+			foreach ($keys as $key) {
+				if (($c = self::read($key)) && is_array($values[$key]) && is_array($c)) {
+					$values[$key] = array_merge_recursive($c, $values[$key]);
+				}
+			}
+		}
+
 		return self::write($values);
 	}
 

cake/tests/cases/libs/configure.test.php

@@ -204,6 +204,13 @@ function testLoad() {
 		$this->assertTrue($result);
 
 		$this->assertEquals('value', Configure::read('Read'));
+
+		$result = Configure::load('var_test2', 'test', true);
+		$this->assertTrue($result);
+
+		$this->assertEquals('value2', Configure::read('Read'));
+		$this->assertEquals('buried2', Configure::read('Deep.Second.SecondDeepest'));
+		$this->assertEquals('buried', Configure::read('Deep.Deeper.Deepest'));
 	}
 
 /**

cake/tests/test_app/config/var_test2.php

@@ -0,0 +1,9 @@
+<?php
+$config = array(
+	'Read' => 'value2',
+	'Deep' => array(
+		'Second' => array(
+			'SecondDeepest' => 'buried2'
+		)
+	)
+);