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Re: qr stringification: why are xism always present? I'm worriedabout backward compatibility

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From:
karl williamson
Date:
August 4, 2010 06:38
Subject:
Re: qr stringification: why are xism always present? I'm worriedabout backward compatibility
Message ID:
4C596D43.3030101@khwilliamson.com
Aristotle Pagaltzis wrote:
> * Ben Morrow <ben@morrow.me.uk> [2010-08-01 22:35]:
>> My alternative suggestion was to introduce a new grouping
>> construct, which I tentatively called (?~sixm:) (I don't much
>> like that, but there aren't many alternatives at this point),
>> which *does* do what you expect; and use that for
>> stringification instead. That way we change the stringification
>> once, now, and then never again.
> 
> I’m unsure about how good an idea that is.
> 
> Presumably the defaults can change in a future version of Perl,
> in which case a stringified pattern that uses this syntax will
> mean different things on different Perl versions. In some cases
> this will even magically do what you want, but it could equally
> be a pitfall.

FWIW, I have given this some thought, and came to the conclusion that 
Perl is almost certainly never going to change the defaults, because of 
the backward compatibility issues.

> 
> Overall I think it *will* lessen difficulties overall, so it’s
> probably worth having… but it will not fix the problem (of, in
> the general sense, semantics versioning) so much as trade one
> manifestation for another.
> 
> Regards,


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