There's actually nothing special about undef. Any scalar will do, including references.

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re^4: How to call a sub-routine ref by tobyink
in thread How to call a sub-routine ref by greengaroo

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