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Postings from July 2001
This is forwarded from a conversation I had with Jeff Friedl.
==========================================================================
Jeff 'japhy/Marillion' Pinyan <jeffp@crusoe.net> wrote:
|> The only problem is (understandable) that $&, while updated in a
|> look-ahead, is NOT "down"dated in a look-behind:
|>
|> "japhy" =~ m{
|> ..
|> (?{ print "<$`><$&><$'>" })
|> (?=
|> ..
|> (?{ print "<$`><$&><$'>" })
|> )
|> (?<=
|> ..
|> (?{ print "<$`><$&><$'>" })
|> )
|> (?{ print "<$`><$&><$'>" })
|> }x;
|>
|> The output is:
|>
|> <><ja><phy>
|> <><japh><y>
|> <><ja><phy>
|> <><ja><phy>
The 2nd one looks like a bug to me. The lookahead is just that, lookahead,
and so I feel that it should never (ever) be part of $&. The other ones
seem as I would expect them.
==========================================================================
I said it didn't seem like a bug, because:
1. look-ahead is a regex, and the modifications done to $& are localized
2. if $& wasn't touched, there'd be little to no information you could
get out of it, apart from capturing (which then bumps up your
following captures)
3. look-behind isn't much of a "regex", and so I don't think it gets
treated the same way internally
What's it seem like to you?
--
Jeff "japhy" Pinyan japhy@pobox.com http://www.pobox.com/~japhy/
I am Marillion, the wielder of Ringril, known as Hesinaur, the Winter-Sun.
Are you a Monk? http://www.perlmonks.com/ http://forums.perlguru.com/
Perl Programmer at RiskMetrics Group, Inc. http://www.riskmetrics.com/
Acacia Fraternity, Rensselaer Chapter. Brother #734
** Manning Publications, Co, is publishing my Perl Regex book **
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