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Re: RFC: Adding \p{foo=/re/}

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Deven T. Corzine
February 6, 2019 02:08
Re: RFC: Adding \p{foo=/re/}
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On Tue, Feb 5, 2019 at 7:33 PM Karl Williamson <>

> Although it's called a technical standard, it's not actually a part of
> the Unicode Standard, and even though those clauses are written as if
> they are requirements, they're not.

That's a good point to keep in mind.

> This was made clear to me when we followed this document closely, and
> then Unicode made a contradictory rule in the actual Standard.  When I
> pointed this out, they (did seem to be embarrassed, and) said UTS 18
> isn't a standard, and they removed the language from it, leaving us in
> the lurch.  There was a deprecation period for people who were using
> what we had furnished, before we fully supported the Standard again.

Sounds like they pulled a technicality to save face...

The lesson here is that Unicode doesn't always know best, and we need to
> exercise judgment in following them.  Various things from this document
> have been withdrawn as a result of my and others questioning them.  One
> I noticed again today is 2.1, where there there used to be an RL2.1
> apparent requirement.  This document appears to have been written by a
> bunch of people sitting around and brainstorming what would be nice, but
> without an implementation to test things out on.

That's probably exactly what happened.

It sucks that they've jerked you around before, but on the bright side,
your questions probably helped make the final standard better, right?

We already differ significantly from their syntaxes.  Our set notation
> is different; we don't have a \p{name=...} syntax, etc.

If there's already syntax differences, I guess that's a decent argument for
requiring "=~/.../" then.

> I knew that they thought the patterns weren't anchored, but my
> experience indicates we should do what we think is best in this regards,
> which may be the unanchored approach.  But I want to hear what people
> think from a perl-based view.

Personally, unanchored would be my vote.  It makes much more sense to me
than anchored, which feels awkward and inconsistent.


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