That's why I commented that there should be a "return, exit, last, or whatever" at the end of the first block. Your version is what I should have arrived at, though.

(I was actually going for a single-if-series solution, but don't know why it didn't occur to me to check the definedness up front. I was irked by having to defined $foo and ... in all conditions before the else-block. Heh. I'm embarrassingly slow lately.)