The problem with "HASH" eq ref($r) is that it will fail if $r is a reference to a blessed hash. Why would you want to refuse to do useful hash stuff on something just because it is blessed?Because a blessed hashref is not a hashref; it's an object. The whole point of an object is encapsulation; to quote The Camel, "In Perl culture, by contrast, you're expected to stay out of someone's home because you weren't invited in, not because there are bars on the windows" (pg. 278, 2nd ed.). i.e., Just because a blessed hashref is a hashref - with modifiable values - at heart doesn't mean i should manipulate it. That could break an object in spectacular ways.