The result of (??{ print $1 }) is 1 because print() succeeded in writing to STDOUT. The regex that was then compiled by (??{ ...}) was "1" which then failed. So the (.) advanced over every character and printed them individually. The proper thing to do here would have been (?{ ... }) which will not affect regex matching.

In reply to Re^2: Dynamic regex assertions, capturing groups, and parsers: joy and terror by diotalevi
in thread Dynamic regex assertions, capturing groups, and parsers: joy and terror by japhy

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