public function set($name, $value = null, $namespace = 'default')
	{
		// Add prefix to namespace to avoid collisions
		$namespace = '__' . $namespace;

		if ($this->getState() !== 'active')
		{
			return;
		}

		$old = isset($_SESSION[$namespace][$name]) ? $_SESSION[$namespace][$name] : null;

		if ($value === null)
		{
			unset($_SESSION[$namespace][$name]);
		}
		else
		{
			$_SESSION[$namespace][$name] = $value;
		}

		return $old;
	}