The OP did imply that the alt tags would be in order in the tag file. I was just making the point that I wouldn't do it that way, but rather, would use a hash to map image names to tags. And the reason is that if you miss-order just one item in the text list, you'll end up screwing up the whole thing. What a mess that could be. Imagine the image of a puppydog showing up with the text for a cat! But even worse, imagine every image past that point also being screwed up.;)

Your method works fine too... as long as there are no mistakes when creating the image alt text file.