No you've got it right. I'd use POSIX character classes but that's because I'm thinking ahead to perl6 and Unicode. It's just a good habit to get into. Your equivalent regex would look like m{[^[:alnum:] ]}. If you mean whitespace in general as opposed to just the literal ' ' character then use \s or :space:.

__SIG__
use B;
printf "You are here %08x\n", unpack "L!", unpack "P4", pack
  "L!", B::svref_2object(sub{})->OUTSIDE;
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