I'm assuming this was in reply to my posting.. I was just offering it as a better way of doing what you were trying to do. Building a hash and setting all of its values to 1 just so you can use that 1 as a true value in a test for the presence of a key
just screams exists
at me. :)
And, following from that logic, if you're going to use exists, what's the point in worrying if you have all of your hash values set to 1 (or anything at all)? Just put an empty list and don't worry about it, and all is well.