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Source   Latest Release: perl-5.26.0-RC2


perl5251delta - what is new for perl v5.25.1


This document describes differences between the 5.25.0 release and the 5.25.1 release.

If you are upgrading from an earlier release such as 5.24.0, first read perl5250delta, which describes differences between 5.24.0 and 5.25.0.

Core Enhancements ^

POSIX::tmpnam() has been removed

The fundamentally unsafe tmpnam() interface was deprecated in Perl 5.22.0 and has now been removed. In its place you can use for example the File::Temp interfaces.

require ::Foo::Bar is now illegal.

Formerly, require ::Foo::Bar would try to read /Foo/ Now any bareword require which starts with a double colon dies instead.

Unescaped literal "{" characters in regular expression patterns are no longer permissible

You have to now say something like "\{" or "[{]" to specify to match a LEFT CURLY BRACKET. This will allow future extensions to the language. This restriction is not enforced, nor are there current plans to enforce it, if the "{" is the first character in the pattern.

These have been deprecated since v5.16, with a deprecation message displayed starting in v5.22.

Literal control character variable names are no longer permissible

A variable name may no longer contain a literal control character under any circumstances. These previously were allowed in single-character names on ASCII platforms, but have been deprecated there since Perl v5.20. This affects things like $\cT, where \cT is a literal control (such as a NAK or NEGATIVE ACKNOWLEDGE character) in the source code.

qr//xx is no longer permissible

Using more than one /x regular expression pattern modifier on a single pattern is now forbidden. This is to allow a future enhancement to the language. This usage has been deprecated since v5.22.

NBSP is no longer permissible in \N{...}

The name of a character may no longer contain non-breaking spaces. It has been deprecated to do so since Perl v5.22.

Performance Enhancements ^

Modules and Pragmata ^

Updated Modules and Pragmata

Documentation ^

Changes to Existing Documentation

Diagnostics ^

New Diagnostics

New Errors

Changes to Existing Diagnostics

Utility Changes ^


Configuration and Compilation ^

Internal Changes ^

Selected Bug Fixes ^

Acknowledgements ^

Perl 5.25.1 represents approximately 2 weeks of development since Perl 5.25.0 and contains approximately 46,000 lines of changes across 630 files from 24 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 40,000 lines of changes to 510 .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 5.25.1:

Aaron Crane, Andreas Voegele, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, David Mitchell, Doug Bell, Father Chrysostomos, H.Merijn Brand, Hugo van der Sanden, Jarkko Hietaniemi, Jerry D. Hedden, Jim Cromie, John Lightsey, Karen Etheridge, Karl Williamson, Lukas Mai, Maxwell Carey, Nicholas Clark, Niko Tyni, Ricardo Signes, Sawyer X, Tony Cook, Yves Orton.

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 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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