Why do you insist on using commas between the words? qw() is a source code beautifying tool, so you can only use it in the source code. There's no way you can apply it to user supplied data.

Simply use whitespace as delimiter, and you can use qw() — with the added advantage that the split is done at compile time, thus once, even in case the code snippet is executed many times, like in a loop or in a sub.