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Source   Latest Release: perl-5.15.9


perl5153delta - what is new for perl v5.15.3


This document describes differences between the 5.15.2 release and the 5.15.3 release.

If you are upgrading from an earlier release such as 5.15.1, first read perl5152delta, which describes differences between 5.15.1 and 5.15.2.

Notice ^

This release includes a rewrite of the perl OO docs which represent a significant modernization of the OO documentation. All of the old OO tutorials (perltoot, perlboot, etc.) have been replaced with pointers to the new docs.

Core Enhancements ^

More CORE subs are callable through references

Perl 5.15.2 introduced subroutines in the CORE namespace. Most of them could only be called as barewords; i.e., they could be aliased at compile time and then inlined under new names.

Almost all of these functions can now be called through references and via &foo() syntax, bypassing the prototype. See CORE for a list of the exceptions.

New debugger commands

The debugger now has disable and enable commands for disabling existing breakpoints and reënabling them. See perldebug.

Security ^

File::Glob::bsd_glob() memory error with GLOB_ALTDIRFUNC (CVE-2011-2728).

Calling File::Glob::bsd_glob with the unsupported flag GLOB_ALTDIRFUNC would cause an access violation / segfault. A Perl program that accepts a flags value from an external source could expose itself to denial of service or arbitrary code execution attacks. There are no known exploits in the wild. The problem has been corrected by explicitly disabling all unsupported flags and setting unused function pointers to null. Bug reported by Clément Lecigne.

Incompatible Changes ^

$[ has been removed

The array/string index offsetting mechanism, controlled by the $[ magic variable, has been removed. $[ now always reads as zero. Writing a zero to it is still permitted, but writing a non-zero value causes an exception. Those hopelessly addicted to FORTRAN-style 1-based indexing may wish to use the module Array::Base, which provides an independent implementation of the index offsetting concept, or Classic::Perl, which allows Array::Base to be controlled through assignment to $[.

User-defined case changing operations.

This feature was deprecated in Perl 5.14, and has now been removed. The CPAN module Unicode::Casing provides better functionality without the drawbacks that this feature had, as are detailed in the 5.14 documentation:

XSUBs are now 'static'

XSUB C functions are now 'static', that is, they are not visible from outside the compilation unit. Users can use the new XS_EXTERNAL(name) and XS_INTERNAL(name) macros to pick the desired linking behaviour. The ordinary XS(name) declaration for XSUBs will continue to declare non-'static' XSUBs for compatibility, but the XS compiler, ExtUtils::ParseXS (xsubpp) will emit 'static' XSUBs by default. ExtUtils::ParseXS's behaviour can be reconfigured from XS using the EXPORT_XSUB_SYMBOLS keyword, see perlxs for details.

Borland compiler

All support for the Borland compiler has been dropped. The code had not worked for a long time anyway.

Weakening read-only references

Weakening read-only references is no longer permitted. It should never hove worked anyway, and in some cases could result in crashes.

Modules and Pragmata ^

Updated Modules and Pragmata

Documentation ^

New Documentation


This a new OO tutorial. It focuses on basic OO concepts, and then recommends that readers choose an OO framework from CPAN.

Changes to Existing Documentation



Removed Documentation

Old OO Documentation

All the old OO tutorials, perltoot, perltooc, and perlboot, have been removed. The perlbot (bag of object tricks) document has been removed as well.

Development Deltas

The old perldelta files for development cycles prior to 5.15 have been removed.

Utility Changes ^


Configuration and Compilation ^

Testing ^

Platform Support ^

Platform-Specific Notes


Remove unnecessary includes, fix miscellaneous compiler warnings and close some unclosed comments on vms/vms.c.

Remove sockadapt layer from the VMS build.

Internal Changes ^

Selected Bug Fixes ^

Known Problems ^

Acknowledgements ^

Perl 5.15.3 represents approximately 2 months of development since Perl 5.15.2 and contains approximately 160,000 lines of changes across 700 files from 44 authors.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.15.3:

Abigail, Alexandr Ciornii, Aristotle Pagaltzis, Chas. Owens, Chip Salzenberg, Chris 'BinGOs' Williams, Craig A. Berry, Damian Conway, Dave Rolsky, David Mitchell, Dominic Hargreaves, Douglas Christopher Wilson, Eric Brine, Father Chrysostomos, Florian Ragwitz, Frederic Briere, George Greer, Gerard Goossen, H.Merijn Brand, Jerry D. Hedden, Jesse Vincent, Jim Cromie, Karl Williamson, Keith Thompson, Leo Lapworth, Leon Timmermans, Lukas Mai, Mark Jason Dominus, Matthew Horsfall, Moritz Lenz, Nicholas Clark, Peter John Acklam, Rafael Garcia-Suarez, Ricardo Signes, Robin Barker, Shlomi Fish, Steffen Müller, Stephen Bennett, Stevan Little, Steve Hay, Tony Cook, Vincent Pit, Walt Mankowski, Zefram.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

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.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.


The Changes file for an explanation of how to view 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.

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