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Re: RFC: New regex modifier flags

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From:
Paul LeoNerd Evans
Date:
August 3, 2010 15:14
Subject:
Re: RFC: New regex modifier flags
Message ID:
20100803221445.GY11110@cel.leo
On Tue, Aug 03, 2010 at 01:22:36PM -0600, karl williamson wrote:
> I think that's it.  Here is your ballot (I briefly what I think are
> the up/downsides.  Feel free to add things.)

Will this be first-past-the-post, or AV? ;)

My votes in preference, are:

> 2) Use two-letter options for the mutually exclusive ones.
> Extensible, visually distinguishable, but /abc/Clip may be hard to
> read.
Most preferred. We've suddenly now bought ourselves precident to have a
great number of other switches and knobs in future, should we find we
require them.

> 3) Use single capital letters for these options; distinguishable,
> not extensible.
2nd choice. A lesser version of the above.

> 5) Use single letter lower case option letters, but until 5.16 they
> are only valid in the (?:) form.  They are not visibly distinguished
> from options that aren't mutually exclusive.
3rd choice. This might not be so bad as their effect is quite locallised
anyway, so

  (?u:\d)   matches a unicode digit

is fairly neat and a resonable way to access the functionallity.

Though, I somewhat dislike either this or 6); see below.

> 6) Use single letter lower case option letters implemented in such a
> way that until 5.16 ambiguities are resolved to the existing
> interpretations.  The option letters are not visibly distinguished
> from options that aren't mutually exclusive.  After the deprecation
> cycle in 5.14, there won't be these ambiguities.  My vote goes to
> this one.
4th choice. Introducing new flags only to then change their behaviour in
short time seems a bit unpredictable.

Also, this and 5) both suffer, in that the mutually-exclusive choice for
the Unicode behaviour should not feel the same as all the current flags,
which are currently orthogonal to each other. Not a -major- problem; to
pick UNIX precident again, we do note that tar -xc are mutually
exclusive but tar -xzv is fine. A little messy but I could live with it.

> 1) Do nothing.  Don't implement this, leave the Unicode bugs there.
5th choice. We do need some Unicode support here, but if we can't think
of a decent way to implement it now, we may want to consider further
thought until a better idea avails itself.

> 4) Use single letter lower case option letters, but choose
> non-mnemonic ones to avoid ambiguities with existing keywords.  They
> are not visibly distinguished from options that aren't mutually
> exclusive.
Last choice. It'd be worse to introduce a poor interface given all the
better ideas that might fit, simply for the expedience of getting a
quick bug fix out now.

-- 
Paul "LeoNerd" Evans

leonerd@leonerd.org.uk
ICQ# 4135350       |  Registered Linux# 179460
http://www.leonerd.org.uk/

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