I thought of that, but that's akin to overriding the as_string method, and would have a global effect (i.e. all string-forms of Frooble would then revert back to Frooble=HASH() form).

What I was after was something like

# prints "Blortz", i.e. the instance name
print "$frooble";

# prints "Frooble=HASH(..)"
print UNIVERSAL::as_string($frooble);
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but unless I'm missing something (not unusual ;) ) nothing like that exists.