in reply to Check if a key exists in several hashes at once

unless ( grep { exists $$_{$foo} } \%hash1, \%hash2, \%hash3 ) {

(You could also use (core module) List::Util's first in the exact same way, but it's not going to make a noticeable difference unless you've benchmarked that this is slowing you down.)

In Section Seekers of Perl Wisdom