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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 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.

       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 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 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 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 languages, while the blocks are
       more artificial groupings of 256 characters based on the Unicode

       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 appending "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 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

       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

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.

       o   The rules for allowing underscores (underbars) in numeric constants
           have been relaxed and simplified: now you can have an underscore
           between digits.

       o   GMAGIC (right-hand side magic) could in many cases such as string
           concatenation be invoked too many times.

       o   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.

       o   Lexicals II: lexicals leaked at file scope into subroutines that
           were declared before the lexicals.

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

       o   The "op_clear" and "op_null" are now exported.

       o   A new special regular expression variable has been introduced: $^N,
           which contains the most-recently closed group (submatch).

       o   utime now supports "utime undef, undef, @files" to change the file
           timestamps to the current time.

       o   The Perl parser has been stress tested using both random input and
           Markov chain input.

       o   "eval "v200"" now works.

       o   VMS now works under PerlIO.

       o   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
       o   Attribute::Handlers - Simpler definition of attribute handlers

       o   ExtUtils::Constant - generate XS code to import C header constants

       o   I18N::Langinfo - query locale information

       o   I18N::LangTags - functions for dealing with RFC3066-style language

       o   libnet - a collection of perl5 modules related to network

           Perl installation leaves libnet unconfigured, use libnetcfg to

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

       o   Locale::Maketext - framework for localization

       o   Memoize - Make your functions faster by trading space for time

       o   NEXT - pseudo-class for method redispatch

       o   Scalar::Util - selection of general-utility scalar subroutines

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

       o   Test::Simple - Basic utilities for writing tests

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

       o   Time::Piece - Object Oriented time objects

           (Previously known as Time::Object.)

       o   Time::Seconds - a simple API to convert seconds to other date

       o   UnicodeCD - Unicode Character Database

   Updated And Improved Modules and Pragmata
       o   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.

       o   Class::Struct now assigns the array/hash element if the accessor is
           called with an array/hash element as the sole argument.

       o   Cwd extension is now (even) faster.

       o   DB_File extension has been updated to version 1.77.

       o   Fcntl, Socket, and Sys::Syslog have been rewritten to use the new-
           style constant dispatch section (see ExtUtils::Constant).

       o   File::Find is now (again) reentrant.  It also has been made more

       o   File::Glob now supports "GLOB_LIMIT" constant to limit the size of
           the returned list of filenames.

       o   IO::Socket::INET now supports "LocalPort" of zero (usually meaning
           that the operating system will make one up.)

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

Utility Changes

       o   The emacs/ is now much faster.

       o   h2ph now supports C trigraphs.

       o   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 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.

       o   libnetcfg has been added to configure the libnet.

       o   The Pod::Html (and thusly pod2html) now allows specifying a cache

New Documentation

       o   Locale::Maketext::TPJ13 is an article about software localization,
           originally published in The Perl Journal #13, republished here with
           kind permission.

       o   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

       o   The Todo and Todo-5.6 files have been merged into perltodo.

       o   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
       o   AIX should now work better with gcc, threads, and 64-bitness.  Also
           the long doubles support in AIX should be better now.  See perlaix.

       o   AtheOS ( ) is a new platform.

       o   DG/UX platform now supports the 5.005-style threads.  See perldgux.

       o   DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers

       o   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.

       o   Mac OS X (or Darwin) should now be able to build Perl even on HFS+
           filesystems.  (The case-insensitivity confused the Perl build

       o   NetWare from Novell is now supported.  See perlnetware.

       o   The Amdahl UTS Unix mainframe platform is now supported.

   Generic Improvements
       o   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".

       o   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.

       o   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

       o   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

       o    The autouse pragma didn't work for Multi::Part::Function::Names.

       o    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 number conversion is
            undefined: now Perl consistently handles such strings as zero in
            numeric contexts.

       o    dprofpp -R didn't work.

       o    PERL5OPT with embedded spaces didn't work.

       o    Sys::Syslog ignored the "LOG_AUTH" constant.

   Platform Specific Changes and Fixes
       o   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

       o   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

       o   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.

       o   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

       o   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 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 cumulative containing known
       problems for all the 5.7 releases.

       o   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.

       o   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 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
       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".)

   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

       o   ext/POSIX/sigaction subtests 6 and 13 may fail.

       o   lib/ExtUtils may spuriously claim that subtest 28 failed, which is
           interesting since the test only has 27 tests.

       o   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

       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

   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 Tying
       This limitation will hopefully be fixed in future.  (Subroutine
       attributes work fine for tying, 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 doubles", 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 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 submitting feedback and patches.

       Send omissions or corrections to <>.

perl v5.14.0                      2011-05-07                   perl572delta(1)

perl 5.14.0 - Generated Tue May 17 14:42:57 CDT 2011
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