PERL572DELTA(1) Perl Programmers Reference Guide PERL572DELTA(1)NAMEperl572delta - what's new for perl v5.7.2
DESCRIPTION
This document describes differences between the 5.7.1
release and the 5.7.2 release.
(To view the differences between the 5.6.0 release and the
5.7.0 release, see perl570delta. To view the differences
between the 5.7.0 release and the 5.7.1 release, see
perl571delta.)
Security Vulnerability Closed
(This change was already made in 5.7.0 but bears repeating
here.)
A security vulnerability affecting all Perl versions prior
to 5.6.1 was found in August 2000. The vulnerability does
not affect default installations and as far as is known
affects only the Linux platform.
You should upgrade your Perl to 5.6.1 as soon as possible.
Patches for earlier releases exist but using the patches
require full recompilation from the source code anyway, so
5.6.1 is your best choice.
See
http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
for more information.
Incompatible Changes
64-bit platforms and malloc
If your pointers are 64 bits wide, the Perl malloc is no
more being used because it simply does not work with 8-byte
pointers. Also, usually the system malloc on such platforms
are much better optimized for such large memory models than
the Perl malloc.
AIX Dynaloading
The AIX dynaloading now uses in AIX releases 4.3 and newer
the native dlopen interface of AIX instead of the old emu-
lated interface. This change will probably break backward
compatibility with compiled modules. The change was made to
make Perl more compliant with other applications like mod-
perl which are using the AIX native interface.
Socket Extension Dynamic in VMS
The Socket extension is now dynamically loaded instead of
being statically built in. This may or may not be a problem
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with ancient TCP/IP stacks of VMS: we do not know since we
weren't able to test Perl in such configurations.
Different Definition of the Unicode Character Classes
\p{In...}
As suggested by the Unicode consortium, the Unicode charac-
ter classes now prefer scripts as opposed to blocks (as
defined by Unicode); in Perl, when the "\p{In....}" and the
"\p{In....}" regular expression constructs are used. This
has changed the definition of some of those character
classes.
The difference between scripts and blocks is that scripts
are the glyphs used by a language or a group of languages,
while the blocks are more artificial groupings of 256 char-
acters based on the Unicode numbering.
In general this change results in more inclusive Unicode
character classes, but changes to the other direction also
do take place: for example while the script "Latin" includes
all the Latin characters and their various diacritic-adorned
versions, it does not include the various punctuation or
digits (since they are not solely "Latin").
Changes in the character class semantics may have happened
if a script and a block happen to have the same name, for
example "Hebrew". In such cases the script wins and
"\p{InHebrew}" now means the script definition of Hebrew.
The block definition in still available, though, by append-
ing "Block" to the name: "\p{InHebrewBlock}" means what
"\p{InHebrew}" meant in perl 5.6.0. For the full list of
affected character classes, see "Blocks" in perlunicode.
Deprecations
The current user-visible implementation of pseudo-hashes
(the weird use of the first array element) is deprecated
starting from Perl 5.8.0 and will be removed in Perl 5.10.0,
and the feature will be implemented differently. Not only
is the current interface rather ugly, but the current imple-
mentation slows down normal array and hash use quite notice-
ably. The "fields" pragma interface will remain available.
The syntaxes "@a->[...]" and "@h->{...}" have now been
deprecated.
The suidperl is also considered to be too much a risk to
continue maintaining and the suidperl code is likely to be
removed in a future release.
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The "package;" syntax ("package" without an argument has
been deprecated. Its semantics were never that clear and
its implementation even less so. If you have used that
feature to disallow all but fully qualified variables, "use
strict;" instead.
The chdir(undef) and chdir('') behaviors to match chdir()
has been deprecated. In future versions, chdir(undef) and
chdir('') will simply fail.
Core Enhancements
In general a lot of fixing has happened in the area of
Perl's understanding of numbers, both integer and floating
point. Since in many systems the standard number parsing
functions like "strtoul()" and "atof()" seem to have bugs,
Perl tries to work around their deficiencies. This results
hopefully in more accurate numbers.
+ The rules for allowing underscores (underbars) in
numeric constants have been relaxed and simplified: now
you can have an underscore between digits.
+ GMAGIC (right-hand side magic) could in many cases such
as string concatenation be invoked too many times.
+ Lexicals I: lexicals outside an eval "" weren't resolved
correctly inside a subroutine definition inside the eval
"" if they were not already referenced in the top level
of the eval""ed code.
+ Lexicals II: lexicals leaked at file scope into subrou-
tines that were declared before the lexicals.
+ Lvalue subroutines can now return "undef" in list con-
text.
+ The "op_clear" and "op_null" are now exported.
+ A new special regular expression variable has been
introduced: $^N, which contains the most-recently closed
group (submatch).
+ utime now supports "utime undef, undef, @files" to
change the file timestamps to the current time.
+ The Perl parser has been stress tested using both random
input and Markov chain input.
+ "eval "v200"" now works.
+ VMS now works under PerlIO.
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+ END blocks are now run even if you exit/die in a BEGIN
block. The execution of END blocks is now controlled by
PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the
new behaviour for perl embedders. This will default in
5.10. See perlembed.
Modules and Pragmata
New Modules and Distributions
+ Attribute::Handlers - Simpler definition of attribute
handlers
+ ExtUtils::Constant - generate XS code to import C header
constants
+ I18N::Langinfo - query locale information
+ I18N::LangTags - functions for dealing with
RFC3066-style language tags
+ libnet - a collection of perl5 modules related to net-
work programming
Perl installation leaves libnet unconfigured, use lib-
netcfg to configure.
+ List::Util - selection of general-utility list subrou-
tines
+ Locale::Maketext - framework for localization
+ Memoize - Make your functions faster by trading space
for time
+ NEXT - pseudo-class for method redispatch
+ Scalar::Util - selection of general-utility scalar sub-
routines
+ Test::More - yet another framework for writing test
scripts
+ Test::Simple - Basic utilities for writing tests
+ Time::HiRes - high resolution ualarm, usleep, and get-
timeofday
+ Time::Piece - Object Oriented time objects
(Previously known as Time::Object.)
+ Time::Seconds - a simple API to convert seconds to other
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date values
+ UnicodeCD - Unicode Character Database
Updated And Improved Modules and Pragmata
+ B::Deparse module has been significantly enhanced. It
now can deparse almost all of the standard test suite
(so that the tests still succeed). There is a make tar-
get "test.deparse" for trying this out.
+ Class::Struct now assigns the array/hash element if the
accessor is called with an array/hash element as the
sole argument.
+ Cwd extension is now (even) faster.
+ DB_File extension has been updated to version 1.77.
+ Fcntl, Socket, and Sys::Syslog have been rewritten to
use the new-style constant dispatch section (see
ExtUtils::Constant).
+ File::Find is now (again) reentrant. It also has been
made more portable.
+ File::Glob now supports "GLOB_LIMIT" constant to limit
the size of the returned list of filenames.
+ IO::Socket::INET now supports "LocalPort" of zero (usu-
ally meaning that the operating system will make one
up.)
+ The vars pragma now supports declaring fully qualified
variables. (Something that "our()" does not and will not
support.)
Utility Changes
+ The emacs/e2ctags.pl is now much faster.
+ h2ph now supports C trigraphs.
+ h2xs uses the new ExtUtils::Constant module which will
affect newly created extensions that define constants.
Since the new code is more correct (if you have two con-
stants where the first one is a prefix of the second
one, the first constant never gets defined), less lossy
(it uses integers for integer constant, as opposed to
the old code that used floating point numbers even for
integer constants), and slightly faster, you might want
to consider regenerating your extension code (the new
scheme makes regenerating easy). h2xs now also supports
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C trigraphs.
+ libnetcfg has been added to configure the libnet.
+ The Pod::Html (and thusly pod2html) now allows specify-
ing a cache directory.
New Documentation
+ Locale::Maketext::TPJ13 is an article about software
localization, originally published in The Perl Journal
#13, republished here with kind permission.
+ More README.$PLATFORM files have been converted into
pod, which also means that they also be installed as
perl$PLATFORM documentation files. The new files are
perlapollo, perlbeos, perldgux, perlhurd, perlmint,
perlnetware, perlplan9, perlqnx, and perltru64.
+ The Todo and Todo-5.6 files have been merged into perl-
todo.
+ Use of the gprof tool to profile Perl has been docu-
mented in perlhack. There is a make target "perl.gprof"
for generating a gprofiled Perl executable.
Installation and Configuration Improvements
New Or Improved Platforms
+ AIX should now work better with gcc, threads, and
64-bitness. Also the long doubles support in AIX should
be better now. See perlaix.
+ AtheOS ( http://www.atheos.cx/ ) is a new platform.
+ DG/UX platform now supports the 5.005-style threads.
See perldgux.
+ DYNIX/ptx platform (a.k.a. dynixptx) is supported at or
near osvers 4.5.2.
+ Several Mac OS (Classic) portability patches have been
applied. We hope to get a fully working port by 5.8.0.
(The remaining problems relate to the changed IO model
of Perl.) See perlmacos.
+ Mac OS X (or Darwin) should now be able to build Perl
even on HFS+ filesystems. (The case-insensitivity con-
fused the Perl build process.)
+ NetWare from Novell is now supported. See perlnetware.
+ The Amdahl UTS UNIX mainframe platform is now supported.
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Generic Improvements
+ In AFS installations one can configure the root of the
AFS to be somewhere else than the default /afs by using
the Configure parameter "-Dafsroot=/some/where/else".
+ The version of Berkeley DB used when the Perl (and,
presumably, the DB_File extension) was built is now
available as @Config{qw(db_version_major
db_version_minor db_version_patch)} from Perl and as
"DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
DB_VERSION_PATCH_CFG" from C.
+ The Thread extension is now not built at all under
ithreads ("Configure -Duseithreads") because it wouldn't
work anyway (the Thread extension requires being Config-
ured with "-Duse5005threads").
+ The "B::Deparse" compiler backend has been so signifi-
cantly improved that almost the whole Perl test suite
passes after being deparsed. A make target has been
added to help in further testing: "make test.deparse".
Selected Bug Fixes
+ The autouse pragma didn't work for
Multi::Part::Function::Names.
+ The behaviour of non-decimal but numeric string con-
stants such as "0x23" was platform-dependent: in some
platforms that was seen as 35, in some as 0, in some as
a floating point number (don't ask). This was caused
by Perl using the operating system libraries in a
situation where the result of the string to number
conversion is undefined: now Perl consistently handles
such strings as zero in numeric contexts.
+ dprofpp -R didn't work.
+ PERL5OPT with embedded spaces didn't work.
+ Sys::Syslog ignored the "LOG_AUTH" constant.
Platform Specific Changes and Fixes
+ Some versions of glibc have a broken modfl(). This
affects builds with "-Duselongdouble". This version of
Perl detects this brokenness and has a workaround for
it. The glibc release 2.2.2 is known to have fixed the
modfl() bug.
New or Changed Diagnostics
+ In the regular expression diagnostics the "<< HERE"
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marker introduced in 5.7.0 has been changed to be "<--
HERE" since too many people found the "<<" to be too
similar to here-document starters.
+ If you try to "pack" in perlfunc a number less than 0 or
larger than 255 using the "C" format you will get an
optional warning. Similarly for the "c" format and a
number less than -128 or more than 127.
+ Certain regex modifiers such as "(?o)" make sense only
if applied to the entire regex. You will an optional
warning if you try to do otherwise.
+ Using arrays or hashes as references (e.g. "%foo->{bar}"
has been deprecated for a while. Now you will get an
optional warning.
Source Code Enhancements
MAGIC constants
The MAGIC constants (e.g. 'P') have been macrofied (e.g.
"PERL_MAGIC_TIED") for better source code readability and
maintainability.
Better commented code
perly.c, sv.c, and sv.h have now been extensively commented.
Regex pre-/post-compilation items matched up
The regex compiler now maintains a structure that identifies
nodes in the compiled bytecode with the corresponding syn-
tactic features of the original regex expression. The
information is attached to the new "offsets" member of the
"struct regexp". See perldebguts for more complete informa-
tion.
gcc -Wall
The C code has been made much more "gcc -Wall" clean. Some
warning messages still remain, though, so if you are compil-
ing with gcc you will see some warnings about dubious prac-
tices. The warnings are being worked on.
New Tests
Several new tests have been added, especially for the lib
subsection.
The tests are now reported in a different order than in ear-
lier Perls. (This happens because the test scripts from
under t/lib have been moved to be closer to the
library/extension they are testing.)
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Note that unlike other sections in this document (which
describe changes since 5.7.0) this section is cumulative
containing known problems for all the 5.7 releases.
AIX
+ In AIX 4.2 Perl extensions that use C++ functions that
use statics may have problems in that the statics are
not getting initialized. In newer AIX releases this has
been solved by linking Perl with the libC_r library, but
unfortunately in AIX 4.2 the said library has an obscure
bug where the various functions related to time (such as
time() and gettimeofday()) return broken values, and
therefore in AIX 4.2 Perl is not linked against the
libC_r.
+ vac 5.0.0.0 May Produce Buggy Code For Perl
The AIX C compiler vac version 5.0.0.0 may produce buggy
code, resulting in few random tests failing, but when
the failing tests are run by hand, they succeed. We
suggest upgrading to at least vac version 5.0.1.0, that
has been known to compile Perl correctly. "lslpp -L|grep
vac.C" will tell you the vac version.
Amiga Perl Invoking Mystery
One cannot call Perl using the "volume:" syntax, that is,
"perl -v" works, but for example "bin:perl -v" doesn't. The
exact reason is known but the current suspect is the ixemul
library.
lib/ftmp-security tests warn 'system possibly insecure'
Don't panic. Read INSTALL 'make test' section instead.
Cygwin intermittent failures of lib/Memoize/t/expire_file 11
and 12
The subtests 11 and 12 sometimes fail and sometimes work.
HP-UX lib/io_multihomed Fails When LP64-Configured
The lib/io_multihomed test may hang in HP-UX if Perl has
been configured to be 64-bit. Because other 64-bit platforms
do not hang in this test, HP-UX is suspect. All other tests
pass in 64-bit HP-UX. The test attempts to create and con-
nect to "multihomed" sockets (sockets which have multiple IP
addresses).
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HP-UX lib/posix Subtest 9 Fails When LP64-Configured
If perl is configured with -Duse64bitall, the successful
result of the subtest 10 of lib/posix may arrive before the
successful result of the subtest 9, which confuses the test
harness so much that it thinks the subtest 9 failed.
Linux With Sfio Fails op/misc Test 48
No known fix.
OS/390
OS/390 has rather many test failures but the situation is
actually better than it was in 5.6.0, it's just that so many
new modules and tests have been added.
Failed Test Stat Wstat Total Fail Failed List of Failed
-----------------------------------------------------------------------------
../ext/B/Deparse.t 14 1 7.14% 14
../ext/B/Showlex.t 1 1 100.00% 1
../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
600 602 604-610
../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
../ext/POSIX/POSIX.t 29 1 3.45% 14
../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
../lib/locale.t 129 33024 117 19 16.24% 99-117
../lib/warnings.t 434 1 0.23% 75
../lib/ExtUtils.t 27 1 3.70% 25
../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
../lib/User/pwent.t 9 1 11.11% 4
op/pat.t 660 6 0.91% 242-243 424-425
626-627
op/split.t 0 9 ?? ?? % ??
op/taint.t 174 3 1.72% 156 162 168
op/tr.t 70 3 4.29% 50 58-59
Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
op/sprintf tests 129 and 130
The op/sprintf tests 129 and 130 are known to fail on some
platforms. Examples include any platform using sfio, and
Compaq/Tandem's NonStop-UX. The failing platforms do not
comply with the ANSI C Standard, line 19ff on page 134 of
ANSI X3.159 1989 to be exact. (They produce something other
than "1" and "-1" when formatting 0.6 and -0.6 using the
printf format "%.0f", most often they produce "0" and "-0".)
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Failure of Thread tests
Note that support for 5.005-style threading remains experi-
mental.
The following tests are known to fail due to fundamental
problems in the 5.005 threading implementation. These are
not new failures--Perl 5.005_0x has the same bugs, but
didn't have these tests.
lib/autouse.t 4
t/lib/thr5005.t 19-20
UNICOS
+ ext/POSIX/sigaction subtests 6 and 13 may fail.
+ lib/ExtUtils may spuriously claim that subtest 28
failed, which is interesting since the test only has 27
tests.
+ Numerous numerical test failures
op/numconvert 209,210,217,218
op/override 7
ext/Time/HiRes/HiRes 9
lib/Math/BigInt/t/bigintpm 1145
lib/Math/Trig 25
These tests fail because of yet unresolved floating
point inaccuracies.
UTS
There are a few known test failures, see perluts.
VMS
Rather many tests are failing in VMS but that actually more
tests succeed in VMS than they used to, it's just that there
are many, many more tests than there used to be.
Here are the known failures from some compiler/platform com-
binations.
DEC C V5.3-006 on OpenVMS VAX V6.2
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[-.ext.list.util.t]tainted..............FAILED on test 3
[-.ext.posix]sigaction..................FAILED on test 7
[-.ext.time.hires]hires.................FAILED on test 14
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
[.op]sprintf............................FAILED on test 12
Failed 8/399 tests, 91.23% okay.
DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and Compaq C V6.2-008
on OpenVMS Alpha V7.1
[-.ext.list.util.t]tainted..............FAILED on test 3
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
Failed 4/399 tests, 92.48% okay.
Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
[-.ext.b]showlex........................FAILED on test 1
[-.ext.list.util.t]tainted..............FAILED on test 3
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
[.op]misc...............................FAILED on test 49
Failed 6/401 tests, 92.77% okay.
Win32
In multi-CPU boxes there are some problems with the I/O
buffering: some output may appear twice.
Localising a Tied Variable Leaks Memory
use Tie::Hash;
tie my %tie_hash => 'Tie::StdHash';
...
local($tie_hash{Foo}) = 1; # leaks
Code like the above is known to leak memory every time the
local() is executed.
Self-tying of Arrays and Hashes Is Forbidden
Self-tying of arrays and hashes is broken in rather deep and
hard-to-fix ways. As a stop-gap measure to avoid people
from getting frustrated at the mysterious results (core
dumps, most often) it is for now forbidden (you will get a
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fatal error even from an attempt).
Variable Attributes are not Currently Usable for Tieing
This limitation will hopefully be fixed in future. (Subrou-
tine attributes work fine for tieing, see
Attribute::Handlers).
Building Extensions Can Fail Because Of Largefiles
Some extensions like mod_perl are known to have issues with
`largefiles', a change brought by Perl 5.6.0 in which file
offsets default to 64 bits wide, where supported. Modules
may fail to compile at all or compile and work incorrectly.
Currently there is no good solution for the problem, but
Configure now provides appropriate non-largefile ccflags,
ldflags, libswanted, and libs in the %Config hash (e.g.,
$Config{ccflags_nolargefiles}) so the extensions that are
having problems can try configuring themselves without the
largefileness. This is admittedly not a clean solution, and
the solution may not even work at all. One potential
failure is whether one can (or, if one can, whether it's a
good idea) link together at all binaries with different
ideas about file offsets, all this is platform-dependent.
The Compiler Suite Is Still Experimental
The compiler suite is slowly getting better but is nowhere
near working order yet.
The Long Double Support is Still Experimental
The ability to configure Perl's numbers to use "long dou-
bles", floating point numbers of hopefully better accuracy,
is still experimental. The implementations of long doubles
are not yet widespread and the existing implementations are
not quite mature or standardised, therefore trying to sup-
port them is a rare and moving target. The gain of more
precision may also be offset by slowdown in computations
(more bits to move around, and the operations are more
likely to be executed by less optimised libraries).
Reporting Bugs
If you find what you think is a bug, you might check the
articles recently posted to the comp.lang.perl.misc news-
group and the perl bug database at http://bugs.perl.org/
There may also be information at http://www.perl.com/perl/ ,
the Perl Home Page.
If you believe you have an unreported bug, please run the
perlbug program included with your release. Be sure to trim
your bug down to a tiny but sufficient test case. Your bug
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report, along with the output of "perl -V", will be sent off
to perlbug@perl.org to be analysed by the Perl porting team.
SEE ALSO
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
HISTORY
Written by Jarkko Hietaniemi <jhi@iki.fi>, with many contri-
butions from The Perl Porters and Perl Users submitting
feedback and patches.
Send omissions or corrections to <perlbug@perl.org>.
perl v5.8.8 2006-06-30 14
