From @Abigail

Created by @Abigail

As far as I know, the effect of a \U, \L or \Q is cancelled by the
first \E encountered, and no nesting happens.

And as long as you use \U and \L, it works this way. However, \Q seems
to behave differently. \Q seems to match with a matching \E, and work
from the inside out.

I don't know what "\Q-\Q-\E-\E-" is supposed to be, both '\-\---' and
'\-\\Q\---' have some logic (although the former would be my favourite);
however, currently "\Q-\Q-\E-\E-" equals '\-\\\-\--', which seems plain
wrong to me.

The following tests fail 5 times (tests 2, 5, 7, 8, and 9), while I think
they should all pass.

  #!/usr/bin/perl

  use strict;
  use warnings;
  no warnings 'syntax';

  use Test​::More tests => 9;

  is "Aa-\UBb-\LCc-\EDd-\EEe-", 'Aa-BB-cc-Dd-Ee-', '\L after \U';
  is "Aa-\UBb-\QCc-\EDd-\EEe-", 'Aa-BB-CC\-Dd-Ee-', '\Q after \U';
  is "Aa-\UBb-\UCc-\EDd-\EEe-", 'Aa-BB-CC-Dd-Ee-', '\U after \U';

  is "Aa-\LBb-\UCc-\EDd-\EEe-", 'Aa-bb-CC-Dd-Ee-', '\U after \L';
  is "Aa-\LBb-\QCc-\EDd-\EEe-", 'Aa-bb-cc\-Dd-Ee-', '\Q after \L';
  is "Aa-\LBb-\LCc-\EDd-\EEe-", 'Aa-bb-cc-Dd-Ee-', '\L after \L';

  is "Aa-\QBb-\UCc-\EDd-\EEe-", 'Aa-Bb\-CC\-Dd-Ee-', '\U after \Q';
  is "Aa-\QBb-\LCc-\EDd-\EEe-", 'Aa-Bb\-cc\-Dd-Ee-', '\L after \Q';
  is "Aa-\QBb-\QCc-\EDd-\EEe-", 'Aa-Bb\-Cc\-Dd-Ee-', '\Q after \Q';

  __END__
 

Flags:
    category=core
    severity=low

Site configuration information for perl v5.8.8:

Configured by abigail at Fri Feb  3 23:37:31 CET 2006.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=linux, osvers=2.4.18-bf2.4, archname=i686-linux-64int-ld
    uname='linux alexandra 2.4.18-bf2.4 #1 son apr 14 09:53:28 cest 2002 i686 unknown '
    config_args='-des -Dusemorebits -Uversiononly -Dmydomain=.abigail.be -Dcf_email=abigail@abigail.be -Dperladmin=abigail@abigail.be -Doptimize=-g -Dcc=gcc -Dprefix=/opt/perl'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=undef uselongdouble=define
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-g',
    cppflags='-DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include'
    ccversion='', gccversion='3.0.4', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='long double', nvsize=12, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -ldl -lm -lcrypt -lutil -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.2.5.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.2.5'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    defined-or


@INC for perl v5.8.8:
    /home/abigail/Perl
    /opt/perl/lib/5.8.8/i686-linux-64int-ld
    /opt/perl/lib/5.8.8
    /opt/perl/lib/site_perl/5.8.8/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.8
    /opt/perl/lib/site_perl/5.8.7/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.7
    /opt/perl/lib/site_perl/5.8.6/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.6
    /opt/perl/lib/site_perl/5.8.5/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.5
    /opt/perl/lib/site_perl/5.8.4/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.4
    /opt/perl/lib/site_perl/5.8.3/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.3
    /opt/perl/lib/site_perl/5.8.2/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.2
    /opt/perl/lib/site_perl/5.8.1/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.1
    /opt/perl/lib/site_perl/5.8.0/i686-linux-64int-ld
    /opt/perl/lib/site_perl/5.8.0
    /opt/perl/lib/site_perl
    .


Environment for perl v5.8.8:
    HOME=/home/abigail
    LANG=C
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/home/abigail/Lib:/usr/local/lib:/usr/lib:/lib:/usr/X11R6/lib
    LOGDIR (unset)
    PATH=/home/abigail/Bin:/opt/perl/bin:/usr/local/bin:/usr/local/X11/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/games:/usr/share/texmf/bin:/opt/Acrobat/bin:/opt/java/blackdown/j2sdk1.3.1/bin:/usr/local/games/bin
    PERL5LIB=/home/abigail/Perl
    PERLDIR=/opt/perl
    PERL_BADLANG (unset)
    SHELL=/bin/bash

From rick@bort.ca

On Mar 23 2007, Abigail wrote​:

As far as I know, the effect of a \U, \L or \Q is cancelled by the
first \E encountered, and no nesting happens.

And as long as you use \U and \L, it works this way. However, \Q seems
to behave differently. \Q seems to match with a matching \E, and work
from the inside out.

I don't know what "\Q-\Q-\E-\E-" is supposed to be, both '\-\---' and
'\-\\Q\---' have some logic (although the former would be my favourite);
however, currently "\Q-\Q-\E-\E-" equals '\-\\\-\--', which seems plain
wrong to me.

I think this is all covered in L<perlop/"Gory details of parsing quoted
constructs">. Basically, everything after \Q is double-quote
interpolated before escaping, which includes interpolating \Q sequences.
So these are all equivalent​:

  print "\Q-\Q-\E-\E";
  print quotemeta("-\Q-\E-\E");
  print quotemeta("-" . "\Q-\E-\E");
  print quotemeta("-" . quotemeta("-\E") . "-\E");

--
Rick Delaney
rick@​bort.ca

The RT System itself - Status changed from 'new' to 'open'

From david@landgren.net

Rick Delaney a écrit :

On Mar 23 2007, Abigail wrote​:

As far as I know, the effect of a \U, \L or \Q is cancelled by the
first \E encountered, and no nesting happens.

And as long as you use \U and \L, it works this way. However, \Q seems
to behave differently. \Q seems to match with a matching \E, and work
from the inside out.

I don't know what "\Q-\Q-\E-\E-" is supposed to be, both '\-\---' and
'\-\\Q\---' have some logic (although the former would be my favourite);
however, currently "\Q-\Q-\E-\E-" equals '\-\\\-\--', which seems plain
wrong to me.

I think this is all covered in L<perlop/"Gory details of parsing quoted
constructs">. Basically, everything after \Q is double-quote
interpolated before escaping, which includes interpolating \Q sequences.
So these are all equivalent​:

print "\\Q\-\\Q\-\\E\-\\E";
print quotemeta\("\-\\Q\-\\E\-\\E"\);
print quotemeta\("\-" \. "\\Q\-\\E\-\\E"\);
print quotemeta\("\-" \. quotemeta\("\-\\E"\) \. "\-\\E"\);

I think the only real bug in all this is

% perl -le "print qq{\Un\lext}"
NEXT

According to the docs, that should print "NeXT". I cam see where and why
in the parser it comes out like this, but at this late stage of the game
I think it would be better to amend to documentation to say that \l and
\u are ignored if a \U or \L are in force.

There's a bug (#9360) open on this issue.

David

There's a bug (#9360) open on this issue.

For reference: in github this is actually issue #5467