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Re: Accepting [xyz---abc] - three minus signs to mean one

From: arnold
Subject: Re: Accepting [xyz---abc] - three minus signs to mean one
Date: Thu, 21 Apr 2022 05:37:18 -0600
User-agent: Heirloom mailx 12.5 7/5/10


Bruno Haible <bruno@clisp.org> wrote:

> Is there some realistic possibility that the POSIX regex syntax might be
> extended in the future, in such a way that [^0-9---] means something
> different?

That shouldn't happen, as one can point at V7 Unix and Unix awk and
mawk as treating --- as "-" since forever. Existing practice trumps
(or should trump) innovative new interpretations.

> If that happens, and if we opt now to assign a meaning to this
> regex, we would have to choose between POSIX compliance and backward
> compatibility — a bad situation.

I don't think it's a realistic worry.

My two cents of course.  I have already pushed this change in gawk's
copy of regex.



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