[26535] in Perl-Users-Digest
Perl-Users Digest, Issue: 8682 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu Nov 17 21:05:31 2005
Date: Thu, 17 Nov 2005 18:05:04 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Thu, 17 Nov 2005 Volume: 10 Number: 8682
Today's topics:
Re: /(foo|)/ vs /(foo)?/ <sdn.girths00869@zoemail.net>
Re: [OT] Google Groups: vote for Default quoting <cwilbur@chromatico.net>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 17 Nov 2005 19:21:16 -0600
From: "Eric J. Roode" <sdn.girths00869@zoemail.net>
Subject: Re: /(foo|)/ vs /(foo)?/
Message-Id: <Xns9711CF34654F0sdn.comcast@216.196.97.136>
-----BEGIN xxx SIGNED MESSAGE-----
Hash: SHA1
Abigail <abigail@abigail.nl> wrote in
news:slrndnpme2.qiv.abigail@alexandra.abigail.nl:
> $_ = "bar";
> print /(foo|) (?(1)|(?!))/x ? "match\n" : "no match\n";
> print /(foo)? (?(1)|(?!))/x ? "match\n" : "no match\n";
> __END__
> match
> no match
Abigail, the master weaver of perl regexes, has once again confounded
me. It ain't the first time. :-) I had never seen (?(...)). I
looked in "perldoc perlre", and it wasn't much help:
"(?(condition)yes-pattern|no-pattern)"
"(?(condition)yes-pattern)"
Conditional expression. "(condition)" should be either an
integer in parentheses (which is valid if the corresponding
pair of parentheses matched), or look-ahead/look-behind/eval-
uate zero-width assertion.
For example:
m{ ( \( )?
[^()]+
(?(1) \) )
}x
matches a chunk of non-parentheses, possibly included in
parentheses themselves.
This.... is vague at best. What is "no-pattern"? What means
"valid"? ("matches", I assume, but perhaps one should not use it if
there's a chance that the numbered parentheses don't match?) Must
the look-ahead/look-behind/evaluate match at that point? If so, how
is it any different than having the assertion at that point *not*
within (?(...))?
If anyone can explain, or point me to a better explanation than
perlre, I would be grateful.
- --
Eric
`$=`;$_=\%!;($_)=/(.)/;$==++$|;($.,$/,$,,$\,$",$;,$^,$#,$~,$*,$:,@%)=(
$!=~/(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/,$"),$=++;$.++;$.++;
$_++;$_++;($_,$\,$,)=($~.$"."$;$/$%[$?]$_$\$,$:$%[$?]",$"&$~,$#,);$,++
;$,++;$^|=$";`$_$\$,$/$:$;$~$*$%[$?]$.$~$*${#}$%[$?]$;$\$"$^$~$*.>&$=`
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------------------------------
Date: Thu, 17 Nov 2005 19:13:02 -0500
From: Charlton Wilbur <cwilbur@chromatico.net>
Subject: Re: [OT] Google Groups: vote for Default quoting
Message-Id: <m2u0eau835.fsf@ubiquity.chromatico.net>
>>>>> "JB" == John Bokma <john@castleamber.com> writes:
JB> Which exclude people working for a company that just firewalls
JB> some ports, or if your Usenet server is down, and you have an
JB> urgent post to make. (Been there).
Not my problem, frankly; they can get their work and their servers to
behave sensibly, or they can cope with me not reading their posts.
The only policies that dictate how I spend my time are those of my
workplace, which compensates me for the inconvenience with money.
If the Google Groups users were to compensate me for my time at a
similar hourly rate, however, I would be pleased to remove the block.
Charlton
--
cwilbur at chromatico dot net
cwilbur at mac dot com
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 8682
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