I used a bigger regex, which contained some such groups. And for avoiding unexpected results, I wanted to use atomics/possessives. And I wanted to capture these groups. So instead of writing /(?> ($pat1) ) (?> ($pat2) )/x I decided to use possessive quantifiers to increase readability :) (my eyes dislike too many parentheses)
I don't have access to code, where I used it, but friend wrote to me, that with perl 5.20 he gained something wrong (warning/error).

In reply to Re^5: about style: use possessive or atomic? by rsFalse
in thread about style: use possessive or atomic? by rsFalse

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