You missed /^[ABC]\z/ which should be faster than an alternation (but is only viable with one letter options). I also wonder about length($str)==1 && $str=~/[ABC]/

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$world=~s/war/peace/g

In reply to Re^2: Collapsing repetitive equality tests: || vs {} vs // (an observation) by demerphq
in thread Collapsing repetitive equality tests: || vs {} vs // (an observation) by blogical

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