$1 will be set to undef after a match with no parentheses.

Is this documented behaviour? I could have sworn I'd used a perl at some point where $1 persisted unless you made another captured match. I could, of course, be making shit up :-)

In reply to Re^2: Determing whether a regexp has capturing matches by adrianh
in thread Determing whether a regexp has capturing matches by adrianh

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