Zend PostCode Validator dependent on Country

PostCode.php

<?php

class My_Validate_PostCode extends Zend_Validate_Abstract
{
	public function isValid($value, $context = null)
	{
		$value = (string) $value;

		if(!(is_array($context) && isset($context['country'])))
		{
			return true;
		}

		$country = $context['country'];

		$locale = Zend_Locale::getLocaleToTerritory($country);
		$validator = new Zend_Validate_PostCode($locale);

		return $validator->isValid($value);
	}
}