In response to http://adamjonrichardson.com/2012/02/06/long-live-the-goto-statement/

val_somewhat_nested.php

<?php
function val_somewhat_nested($name = null, $value = null, $is_mutable = false) {
	static $values = array();
	static $mutables = array();

	if($name === null)
		return $values;

	if($value === null)
		return isset($values[$name]) ? $values[$name] : null;

	if(isset($values[$name]) && ! in_array($name, $mutables))
		throw new Exception('The value "' . $name . '" is immutable and has already been set to '.$values[$name].'.');
	
	if($is_mutable)
		$mutables[] = $name;

	return $values[$name] = $value;		
}