lib/merry/Config.php
protected function walk(&$ptr, $key, $val, $key_sep) {
		foreach (explode($key_sep, $key) as $sub) {
			$ptr = &$ptr[$sub];
		}
		$ptr = $val;
	}
protected function walk(&$ptr, $key, $val, $key_sep) {
		foreach (explode($key_sep, $key) as $sub) {
			$ptr = &$ptr[$sub];
		}
		$ptr = $val;
	}
Walk a key split by the key separator into an array up and set the
respective value on the leaf
@param mixed $ptr current leaf pointer in the array
@param string $key the array key
@param mixed $val the value to set
@param string $key_sep the key separator for traversal