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PERL572DELTA(1)        Perl Programmers Reference Guide        PERL572DELTA(1)

       perl572delta - what's new for perl v5.7.2

       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 dif-
       ferences 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 vulnerabil-
       ity 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 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 emulated interface.  This change will probably break backward compatibility with compiled modules.  The
       change was made to make Perl more compliant with other applications like modperl which are using the AIX native

       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 with ancient TCP/IP stacks of VMS: we do not know since we weren't able to test Perl in such configura-

       Different Definition of the Unicode Character Classes \p{In...}

       As suggested by the Unicode consortium, the Unicode character 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 lan-
       guages, while the blocks are more artificial groupings of 256 characters 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

       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 appending "Block" to the name: "\p{InHebrew-
       Block}" means what "\p{InHebrew}" meant in perl 5.6.0.  For the full list of affected character classes, see
       "Blocks" in perlunicode.


       The current user-visible implementation of pseudo-hashes (the weird use of the first array element) is depre-
       cated starting from Perl 5.8.0 and will be removed in Perl 5.10.0, and the feature will be implemented differ-
       ently.  Not only is the current interface rather ugly, but the current implementation slows down normal array
       and hash use quite noticeably. 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.

       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 vari-
       ables, "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 float-
       ing 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 subroutines that were declared before the lexicals.

       ?   Lvalue subroutines can now return "undef" in list context.

       ?   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.

       ?   END blocks are now run even if you exit/die in a BEGIN block.  The execution of END blocks is now con-
           trolled 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 network programming

           Perl installation leaves libnet unconfigured, use libnetcfg to configure.

       ?   List::Util - selection of general-utility list subroutines

       ?   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 subroutines

       ?   Test::More - yet another framework for writing test scripts

       ?   Test::Simple - Basic utilities for writing tests

       ?   Time::HiRes - high resolution ualarm, usleep, and gettimeofday

       ?   Time::Piece - Object Oriented time objects

           (Previously known as Time::Object.)

       ?   Time::Seconds - a simple API to convert seconds to other 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 target "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

       ?   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 (usually meaning that the operating system will make one

       ?   The vars pragma now supports declaring fully qualified variables.  (Something that "our()" does not and
           will not support.)

Utility Changes
       ?   The emacs/ is now much faster.

       ?   h2ph now supports C trigraphs.

       ?   h2xs uses the new ExtUtils::Constant module which will affect newly created extensions that define con-
           stants.  Since the new code is more correct (if you have two constants 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 C trigraphs.

       ?   libnetcfg has been added to configure the libnet.

       ?   The Pod::Html (and thusly pod2html) now allows specifying 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 perltodo.

       ?   Use of the gprof tool to profile Perl has been documented 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 ( ) 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
           confused the Perl build process.)

       ?   NetWare from Novell is now supported.  See perlnetware.

       ?   The Amdahl UTS UNIX mainframe platform is now supported.

       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_VER-

       ?   The Thread extension is now not built at all under ithreads ("Configure -Duseithreads") because it wouldn't
           work anyway (the Thread extension requires being Configured with "-Duse5005threads").

       ?   The "B::Deparse" compiler backend has been so significantly 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 constants 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 num-
            ber 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" 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 corre-
       sponding syntactic features of the original regex expression.  The information is attached to the new "offsets"
       member of the "struct regexp". See perldebguts for more complete information.

       gcc -Wall

       The C code has been made much more "gcc -Wall" clean.  Some warning messages still remain, though, so if you
       are compiling with gcc you will see some warnings about dubious practices.  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 earlier Perls.  (This happens because the test scripts
       from under t/lib have been moved to be closer to the library/extension they are testing.)

Known Problems
       Note that unlike other sections in this document (which describe changes since 5.7.0) this section is cumula-
       tive containing known problems for all the 5.7 releases.


       ?   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 May Produce Buggy Code For Perl

           The AIX C compiler vac version 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
 , that has been known to compile Perl correctly.  "lslpp -L|grep vac.C" will tell you the vac ver-

       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 connect to "multihomed" sockets (sockets which have multiple IP addresses).

       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 sub-
       test 9 failed.

       Linux With Sfio Fails op/misc Test 48

       No known fix.


       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
        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".)

       Failure of Thread tests

       Note that support for 5.005-style threading remains experimental.

       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


       ?   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

       ?   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.


       There are a few known test failures, see perluts.


       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 combinations.

       DEC C V5.3-006 on OpenVMS VAX V6.2

         [-.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.


       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 fatal error even from an attempt).

       Variable Attributes are not Currently Usable for Tieing

       This limitation will hopefully be fixed in future.  (Subroutine attributes work fine for tieing, see

       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 doubles", floating point numbers of hopefully better accu-
       racy, 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 support 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
       newsgroup and the perl bug database at  There may also be information at , 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 report, along with the output of "perl -V",
       will be sent off to to be analysed by the Perl porting team.

       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.

       Written by Jarkko Hietaniemi <>, with many contributions from The Perl Porters and Perl Users submit-
       ting feedback and patches.

       Send omissions or corrections to <>.

perl v5.8.8                       2006-01-07                   PERL572DELTA(1)