#!/usr/bin/perl

use strict;
use warnings;

my $filedata = "Here is XYZ_ABC_123456.7890 Foo Bar";

my $mode = ( @ARGV and $ARGV[0] =~ /u/ ) ? ":utf8" : '';

open I, "<$mode", \$filedata ;
while (<I>) {
    my ( $id ) = ( /(XYZ_ABC_[\d.]+)/ );
    print "ID is $id\n";
}

##</code><code>##

$ perl test.pl            # no debugger, not utf8
ID is XYZ_ABC_123456.7890

$ perl test.pl u          # no debugger, utf8
ID is XYZ_ABC_123456.7890

$ perl -d test.pl         # debugging, not utf8

Loading DB routines from perl5db.pl version 1.28
...

main::(test.pl:6):      my $filedata = "Here is XYZ_ABC_123456.7890 Foo Bar";

DB<1> c
ID is XYZ_ABC_123456.7890
Debugged program terminated...

DB<1> q


## and now the kicker:

$ perl -d test.pl u       # debugging, utf8

Loading DB routines from perl5db.pl version 1.28
...

main::(test.pl:6):      my $filedata = "Here is XYZ_ABC_123456.7890 Foo Bar";

DB<1> c
perl(18841) malloc: *** vm_allocate(size=4294832128) failed (error code=3)
perl(18841) malloc: *** error: can't allocate region
perl(18841) malloc: *** set a breakpoint in szone_error to debug
Out of memory!
Debugged program terminated.  Use q to quit or R to restart,
  use O inhibit_exit to avoid stopping after program termination,
  h q, h R or h O to get additional info.

DB<1> q

$ perl -v

This is perl, v5.8.6 built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)


##</code><code>##

Summary of my perl5 (revision 5 version 8 subversion 6) configuration:
  Platform:
    osname=darwin, osvers=8.0, archname=darwin-thread-multi-2level
    uname='darwin b28.apple.com 8.0 darwin kernel version 7.5.0: thu mar 3 18:48:46 pst 2005; root:xnuxnu-517.99.13.obj~1release_ppc power macintosh powerpc '
    config_args='-ds -e -Dprefix=/usr -Dccflags=-g  -pipe  -Dldflags=-Dman3ext=3pm -Duseithreads -Duseshrplib'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-g -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include',
    optimize='-Os',
    cppflags='-no-cpp-precomp -g -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.3 20030304 (Apple Computer, Inc. build 1809)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=4321
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags ='-L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lc
    perllibs=-ldl -lm -lc
    libc=/usr/lib/libc.dylib, so=dylib, useshrplib=true, libperl=libperl.dylib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-bundle -undefined dynamic_lookup -L/usr/local/lib'


Characteristics of this binary (from libperl): 
  Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES PERL_IMPLICIT_CONTEXT
  Locally applied patches:
        23953 - fix for File::Path::rmtree CAN-2004-0452 security issue
        33990 - fix for setuid perl security issues
  Built under darwin
  Compiled at Mar 20 2005 16:34:19
  @INC:
    /System/Library/Perl/5.8.6/darwin-thread-multi-2level
    /System/Library/Perl/5.8.6
    /Library/Perl/5.8.6/darwin-thread-multi-2level
    /Library/Perl/5.8.6
    /Library/Perl
    /Network/Library/Perl/5.8.6/darwin-thread-multi-2level
    /Network/Library/Perl/5.8.6
    /Network/Library/Perl
    /System/Library/Perl/Extras/5.8.6/darwin-thread-multi-2level
    /System/Library/Perl/Extras/5.8.6
    /Library/Perl/5.8.1/darwin-thread-multi-2level
    /Library/Perl/5.8.1
    .

##</code><code>##

panic: pp_match start/end pointers at my_real_script.perl line 61, <I> chunk 2.
 at my_real_script.perl line 61

### or, alternatively (if I try to single-step past line 61:

Out of memory during ridiculously large request at my_real_script.perl line 61, <I> chunk 2.