MirBSD manpage: perl572delta(1)

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 differences
     between the 5.7.0 release and the 5.7.1 release, see

Security Vulnerability Closed

     (This change was already made in 5.7.0 but bears repeating

     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.

     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

     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

     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.


     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

     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-

     +   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

     +   ExtUtils::Constant - generate XS code to import C header

     +   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-

     +   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-

     +   Test::More - yet another framework for writing test

     +   Test::Simple - Basic utilities for writing tests

     +   Time::HiRes - high resolution ualarm, usleep, and get-

     +   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

     +   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

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

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-

     +   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_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

     +    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

     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-

     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

     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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Known Problems

     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.


     +   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

     +   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 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

     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

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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 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".)

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     Failure of Thread tests

     Note that support for 5.005-style threading remains experi-

     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 com-

     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.


     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

     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.


     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 <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>.

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