In my experience object IDs almost always use the stringified reference as a hash key (the usual way for inside-out objects.) Or Scalar::Util::refaddr is used (as in Class::Std and PBP.)

refaddr returns the numified reference, but Scalar::Util already turns warnings off when munging that. (And SU does it in a rather bizarre way with a regex and hex instead of using direct numification for reasons that remain mysterious to me.)

I don't think there are many common uses of numified references outside those two contexts.

Update: Actually it looks like the issue with refaddr is fixed in recent versions. It uses int now.

In reply to Re^2: The trap of reference numification by friedo
in thread The trap of reference numification by samtregar

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