public static function doesClassExtendClass($childClassName, $parentClassName) {

        $reflectionClass = new \ReflectionClass ($childClassName);

        do {
            if ($reflectionClass->getName() == $parentClassName)
                return true;
            $reflectionClass = $reflectionClass->getParentClass();
        } while ($reflectionClass);

        // Assume false if we get this far
        return false;
    }