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perl5259delta - what is new for perl v5.25.9


This document describes differences between the 5.25.8 release and the 5.25.9 release.

If you are upgrading from an earlier release such as 5.25.7, first read perl5258delta, which describes differences between 5.25.7 and 5.25.8.

Core Enhancements ^

New regular expression modifier /xx

Specifying two x characters to modify a regular expression pattern does everything that a single one does, but additionally TAB and SPACE characters within a bracketed character class are generally ignored and can be added to improve readability, like /[ ^ A-Z d-f p-x ]/xx. Details are at "/x and /xx" in perlre.

Deprecations ^

String delimiters that aren't stand-alone graphemes are now deprecated

In order for Perl to eventually allow string delimiters to be Unicode grapheme clusters (which look like a single character, but may be a sequence of several ones), we have to stop allowing a single char delimiter that isn't a grapheme by itself. These are unlikely to exist in actual code, as they would typically display as attached to the character in front of them.

Performance Enhancements ^

Modules and Pragmata ^

Updated Modules and Pragmata

Documentation ^

New Documentation


This file documents all upcoming deprecations, and some of the deprecations which already have been removed. The purpose of this documentation is two-fold: document what will disappear, and by which version, and serve as a guide for people dealing with code which has features that no longer work after an upgrade of their perl.

Diagnostics ^

The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see perldiag.

New Diagnostics

New Warnings

Changes to Existing Diagnostics

As of Perl 5.25.9, all new deprecations will come with a version in which the feature will disappear. And with a few exceptions, most existing deprecations will state when they'll disappear. As such, most deprecation messages have changed.

Utility Changes ^

c2ph and pstruct


Configuration and Compilation ^

Internal Changes ^

Selected Bug Fixes ^

Acknowledgements ^

Perl 5.25.9 represents approximately 4 weeks of development since Perl 5.25.8 and contains approximately 24,000 lines of changes across 400 files from 23 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 17,000 lines of changes to 220 .pm, .t, .c and .h files.

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 5.25.9:

Aaron Crane, Abigail, Andreas König, Andy Lester, Aristotle Pagaltzis Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Collins, David Mitchell, Father Chrysostomos, Hugo van der Sanden, James E Keenan, Jerry D. Hedden, John Lightsey, Karl Williamson, Paul Marquess, Peter Avalos, Sawyer X, Steve Hay, Tomasz Konojacki, Tony Cook, 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 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 see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.


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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