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On Thu, Jul 16, 2015 at 4:36 PM, Rena <hyperhacker@gmail.com> wrote:
> On Jul 16, 2015 6:04 AM, "John Hind" <john.hind@zen.co.uk> wrote:
>
>> New character classes are unlikely to break existing code.
>
> Except code that builds patterns from user input and escapes it like gsub(s,
> "%W", "%%1").

Solution: forget %^ and %$ completely and use %b (beginning) and %e
(end) instead. Neither of those letters are currently in use for
character classes, so nothing would break, and the letters would be
easy to remember.

Plus, by using letters, the standard trick of capitalizing the letter
can be used to say "anything but the beginning/end of the string". Not
sure how useful that would be, but it would be available if someone
wanted it.