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Re: [perl #104906] Data::Dumper will not correctly create eval-ablecode for self-referntial structures
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From:
demerphq
Date:
November 30, 2011 03:18
Subject:
Re: [perl #104906] Data::Dumper will not correctly create eval-ablecode for self-referntial structures
Message ID:
CANgJU+V7O33hvWKvwD4QRSnjkgnASW5_mGwOtT7Qt1yZ8VQHew@mail.gmail.com
Not a bug. Data::Dumper doesn't say it does this.
You can easily use Data::Dumper in a way it does not matter.
For instance
my $dump= 'do{' . Data::Dumper->new([$x,$y,$z], [qw($x $y
$z)])->Purity(1)->Dump() . ' ($x,$y,$z) }'
cheers,
yves
On 29 November 2011 22:25, goldstei@ugcs.caltech.edu
<perlbug-followup@perl.org> wrote:
> # New Ticket Created by goldstei@ugcs.caltech.edu
> # Please include the string: [perl #104906]
> # in the subject line of all future correspondence about this issue.
> # <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=104906 >
>
>
>
> This is a bug report for perl from goldstei@ugcs.caltech.edu,
> generated with the help of perlbug 1.39 running under perl 5.10.1.
>
>
> -----------------------------------------------------------------
> [Please describe your issue here]
>
> I've noticed that Data::Dumper does not always create ouput that will eval
> correctly for self-referential structures, even if Purity=1.
>
> For example, take this code:
>
> ====================
> use Data::Dumper;
>
> my $h = {b => 1};
> my $m = {c => $h};
> $h->{d} = $m;
> $h->{a}[0] = $m;
> $Data::Dumper::Purity = 1;
> print Dumper($h) . "\n";
> my $s = Dumper($h);
> my $a = eval $s;
> print Dumper($a);
> ====================
>
> This produces the output:
>
> ====================
> $VAR1 = {
> 'a' => [
> {
> 'c' => {}
> }
> ],
> 'b' => 1,
> 'd' => {}
> };
> $VAR1->{'a'}[0]{'c'} = $VAR1;
> $VAR1->{'d'} = $VAR1->{'a'}[0];
>
> $VAR1 = {
> 'c' => {
> 'a' => [
> {}
> ],
> 'b' => 1,
> 'd' => {}
> }
> };
> $VAR1->{'c'}{'a'}[0] = $VAR1;
> $VAR1->{'c'}{'d'} = $VAR1;
> ====================
>
> Note that the first outputs $h, while the second outputs $m. This is because,
> as the 'eval' function description states:
>
> "In both forms, the value returned is the value of the last expression
> evaluated inside the mini-program; a return statement may be also used, just as
> with subroutines. The expression providing the return value is evaluated in
> void, scalar, or list context, depending on the context of the eval itself."
>
> The correct output could be obtained by adding a '$VAR1' at the end of the
> structure, whenever the structure is self-referential.
>
> This issue also appears to be present as late as perl 5.12.4.
>
> [Please do not change anything below this line]
> -----------------------------------------------------------------
> ---
> Flags:
> category=library
> severity=low
> module=Data::Dumper
> ---
> Site configuration information for perl 5.10.1:
>
> Configured by Debian Project at Thu Jun 30 22:25:10 UTC 2011.
>
> Summary of my perl5 (revision 5 version 10 subversion 1) configuration:
>
> Platform:
> osname=linux, osvers=2.6.32-5-amd64, archname=x86_64-linux-gnu-thread-multi
> uname='linux brahms 2.6.32-5-amd64 #1 smp tue jun 14 09:42:28 utc 2011 x86_64 gnulinux '
> config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.10.1 -Dsitearch=/usr/local/lib/perl/5.10.1 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.1 -Dd_dosuid -des'
> hint=recommended, useposix=true, d_sigaction=define
> useithreads=define, usemultiplicity=define
> useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
> use64bitint=define, use64bitall=define, uselongdouble=undef
> usemymalloc=n, bincompat5005=undef
> Compiler:
> cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
> optimize='-O2 -g',
> cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
> ccversion='', gccversion='4.4.5', gccosandvers=''
> intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
> d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
> ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
> alignbytes=8, prototype=define
> Linker and Libraries:
> ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
> libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
> libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
> perllibs=-ldl -lm -lpthread -lc -lcrypt
> libc=/lib/libc-2.11.2.so, so=so, useshrplib=true, libperl=libperl.so.5.10.1
> gnulibc_version='2.11.2'
> Dynamic Linking:
> dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
> cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib -fstack-protector'
>
> Locally applied patches:
> DEBPKG:debian/arm_thread_stress_timeout - http://bugs.debian.org/501970 Raise the timeout of ext/threads/shared/t/stress.t to accommodate slower build hosts
> DEBPKG:debian/cpan_config_path - Set location of CPAN::Config to /etc/perl as /usr may not be writable.
> DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
> DEBPKG:debian/db_file_ver - http://bugs.debian.org/340047 Remove overly restrictive DB_File version check.
> DEBPKG:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.
> DEBPKG:debian/enc2xs_inc - http://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
> DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
> DEBPKG:debian/extutils_hacks - Various debian-specific ExtUtils changes
> DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.
> DEBPKG:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.
> DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.
> DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.
> DEBPKG:debian/m68k_thread_stress - http://bugs.debian.org/495826 Disable some threads tests on m68k for now due to missing TLS.
> DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
> DEBPKG:debian/module_build_man_extensions - http://bugs.debian.org/479460 Adjust Module::Build manual page extensions for the Debian Perl policy
> DEBPKG:debian/perl_synopsis - http://bugs.debian.org/278323 Rearrange perl.pod
> DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
> DEBPKG:debian/use_gdbm - Explicitly link against -lgdbm_compat in ODBM_File/NDBM_File.
> DEBPKG:fixes/assorted_docs - http://bugs.debian.org/443733 [384f06a] Math::BigInt::CalcEmu documentation grammar fix
> DEBPKG:fixes/net_smtp_docs - http://bugs.debian.org/100195 [rt.cpan.org #36038] Document the Net::SMTP 'Port' option
> DEBPKG:fixes/processPL - http://bugs.debian.org/357264 [rt.cpan.org #17224] Always use PERLRUNINST when building perl modules.
> DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
> DEBPKG:fixes/pod2man-index-backslash - http://bugs.debian.org/521256 Escape backslashes in .IX entries
> DEBPKG:debian/disable-zlib-bundling - Disable zlib bundling in Compress::Raw::Zlib
> DEBPKG:fixes/kfreebsd_cppsymbols - http://bugs.debian.org/533098 [3b910a0] Add gcc predefined macros to $Config{cppsymbols} on GNU/kFreeBSD.
> DEBPKG:debian/cpanplus_definstalldirs - http://bugs.debian.org/533707 Configure CPANPLUS to use the site directories by default.
> DEBPKG:debian/cpanplus_config_path - Save local versions of CPANPLUS::Config::System into /etc/perl.
> DEBPKG:fixes/kfreebsd-filecopy-pipes - http://bugs.debian.org/537555 [16f708c] Fix File::Copy::copy with pipes on GNU/kFreeBSD
> DEBPKG:fixes/anon-tmpfile-dir - http://bugs.debian.org/528544 [perl #66452] Honor TMPDIR when open()ing an anonymous temporary file
> DEBPKG:fixes/abstract-sockets - http://bugs.debian.org/329291 [89904c0] Add support for Abstract namespace sockets.
> DEBPKG:fixes/hurd_cppsymbols - http://bugs.debian.org/544307 [eeb92b7] Add gcc predefined macros to $Config{cppsymbols} on GNU/Hurd.
> DEBPKG:fixes/autodie-flock - http://bugs.debian.org/543731 Allow for flock returning EAGAIN instead of EWOULDBLOCK on linux/parisc
> DEBPKG:fixes/archive-tar-instance-error - http://bugs.debian.org/539355 [rt.cpan.org #48879] Separate Archive::Tar instance error strings from each other
> DEBPKG:fixes/positive-gpos - http://bugs.debian.org/545234 [perl #69056] [c584a96] Fix \\G crash on first match
> DEBPKG:debian/devel-ppport-ia64-optim - http://bugs.debian.org/548943 Work around an ICE on ia64
> DEBPKG:fixes/trie-logic-match - http://bugs.debian.org/552291 [perl #69973] [0abd0d7] Fix a DoS in Unicode processing [CVE-2009-3626]
> DEBPKG:fixes/hppa-thread-eagain - http://bugs.debian.org/554218 make the threads-shared test suite more robust, fixing failures on hppa
> DEBPKG:fixes/crash-on-undefined-destroy - http://bugs.debian.org/564074 [perl #71952] [1f15e67] Fix a NULL pointer dereference when looking for a DESTROY method
> DEBPKG:fixes/tainted-errno - http://bugs.debian.org/574129 [perl #61976] [be1cf43] fix an errno stringification bug in taint mode
> DEBPKG:fixes/safe-upgrade - http://bugs.debian.org/582978 Upgrade Safe.pm to 2.25, fixing CVE-2010-1974
> DEBPKG:fixes/tell-crash - http://bugs.debian.org/578577 [f4817f3] Fix a tell() crash on bad arguments.
> DEBPKG:fixes/format-write-crash - http://bugs.debian.org/579537 [perl #22977] [421f30e] Fix a crash in format/write
> DEBPKG:fixes/arm-alignment - http://bugs.debian.org/289884 [f1c7503] Prevent gcc from optimizing the alignment test away on armel
> DEBPKG:fixes/fcgi-test - Fix a failure in CGI/t/fast.t when FCGI is installed
> DEBPKG:fixes/hurd-ccflags - http://bugs.debian.org/587901 Make hints/gnu.sh append to $ccflags rather than overriding them
> DEBPKG:debian/squelch-locale-warnings - http://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
> DEBPKG:fixes/lc-numeric-docs - http://bugs.debian.org/379329 [perl #78452] [903eb63] LC_NUMERIC documentation fixes
> DEBPKG:fixes/lc-numeric-sprintf - http://bugs.debian.org/601549 [perl #78632] [b3fd614] Fix sprintf not to ignore LC_NUMERIC with constants
> DEBPKG:fixes/concat-stack-corruption - http://bugs.debian.org/596105 [perl #78674] [e3393f5] Fix stack pointer corruption in pp_concat() with 'use encoding'
> DEBPKG:fixes/cgi-multiline-header - http://bugs.debian.org/606995 [CVE-2010-2761 CVE-2010-4410 CVE-2010-4411] CGI.pm MIME boundary and multiline header vulnerabilities
> DEBPKG:fixes/casing-taint-cve-2011-1487 - http://bugs.debian.org/622817 [perl #87336] fix unwanted taint laundering in lc(), uc() et al.
> DEBPKG:fixes/safe-reval-rdo-cve-2010-1447 - [PATCH] Wrap by default coderefs returned by rdo and reval
> DEBPKG:patchlevel - http://bugs.debian.org/567489 List packaged patches for 5.10.1-17squeeze2 in patchlevel.h
>
> ---
> @INC for perl 5.10.1:
> /etc/perl
> /usr/local/lib/perl/5.10.1
> /usr/local/share/perl/5.10.1
> /usr/lib/perl5
> /usr/share/perl5
> /usr/lib/perl/5.10
> /usr/share/perl/5.10
> /usr/local/lib/site_perl
> .
>
> ---
> Environment for perl 5.10.1:
> HOME=/afs/.ugcs/user/goldstei
> LANG=en_US.UTF-8
> LANGUAGE (unset)
> LD_LIBRARY_PATH (unset)
> LOGDIR (unset)
> PATH=/afs/.ugcs/user/goldstei/ugcs2/scripts:/usr/ug/bin:/usr/ug/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/ug/adm/bin/scripts:/ug/adm/bin/:/usr/X11R6/bin:/afs/.ugcs/user/goldstei/bin:/afs/.ugcs/user/goldstei/maple10/bin:/mnt/cresol/cresol/ufs/egnor/i386-linux2/bin:/usr/ug/share/scripts:/afs/.ugcs/user/goldstei/ugcs2/scripts:/usr/ug/bin:/usr/ug/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/ug/adm/bin/scripts:/ug/adm/bin/:/usr/X11R6/bin:/afs/.ugcs/user/goldstei/bin:/afs/.ugcs/user/goldstei/maple10/bin:/mnt/cresol/cresol/ufs/egnor/i386-linux2/bin:/usr/ug/share/scripts:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games
> PERL_BADLANG (unset)
> SHELL=/bin/zsh
>
--
perl -Mre=debug -e "/just|another|perl|hacker/"
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