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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 5, 2010 10:23
Subject:
Re: qr stringification: why are xism always present? I'm worriedabout backward compatibility
Message ID:
4C5AF389.6050604@khwilliamson.com
Aristotle Pagaltzis wrote:
> * karl williamson <public@khwilliamson.com> [2010-08-04 15:40]:
>> 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.
> 
> Yet you *are* changing the past default right now, *in spite* of
> back compat issues… :-)
> 
> Regards,

I'm not sure I understand.  The default options remain the same.  Ben 
made the point in your quote above that by doing this now when we are 
pretty much agreed that something should be done will cause this to 
likely be the last time adding a flag would cause backward compatibility 
issues.

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