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Max Maischein > perl-5.15.8 > perl5155delta


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Source   Latest Release: perl-5.15.9


perl5155delta - what is new for perl v5.15.5


This document describes differences between the 5.15.4 release and the 5.15.5 release.

If you are upgrading from an earlier release such as 5.15.3, first read perl5154delta, which describes differences between 5.15.3 and 5.15.4.

Core Enhancements ^

More consistent eval

The eval operator sometimes treats a string argument as a sequence of characters and sometimes as a sequence of bytes, depending on the internal encoding. The internal encoding is not supposed to make any difference, but there is code that relies on this inconsistency.

Under use v5.15 and higher, the unicode_eval and evalbytes features resolve this. The unicode_eval feature causes eval $string to treat the string always as Unicode. The evalbytes features provides a function, itself called evalbytes, which evaluates its argument always as a string of bytes.

These features also fix oddities with source filters leaking to outer dynamic scopes.

See feature for more detail.

$[ is back

The $[ variable is back again, but is now implemented as a module, so programs that do not mention it (i.e., most of them), will not incur any run-time penalty. In a later release in the 5.15 branch it might be disabled in the scope of use v5.16.

The new implementation has some bug fixes. See arybase.

Security ^

Privileges are now set correctly when assigning to $(

A hypothetical bug (probably non-exploitable in practice) due to the incorrect setting of the effective group ID while setting $( has been fixed. The bug would only have affected systems that have setresgid() but not setregid(), but no such systems are known of.

Incompatible Changes ^

Certain deprecated Unicode properties are no longer supported by default

Perl should never have exposed certain Unicode properties that are used by Unicode internally and not meant to be publicly available. Use of these has generated deprecated warning messages since Perl 5.12. The removed properties are Other_Alphabetic, Other_Default_Ignorable_Code_Point, Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase, Other_Math, and Other_Uppercase.

Perl may be recompiled to include any or all of them; instructions are given in "Unicode character properties that are NOT accepted by Perl" in perluniprops.

Dereferencing IO thingies as typeglobs

The *{...} operator, when passed a reference to an IO thingy (as in *{*STDIN{IO}}), creates a new typeglob containing just that IO object.

Previously, it would stringify as an empty string, but some operators would treat it as undefined, producing an "uninitialized" warning.

Having a typeglob appear as an empty string is a side effect of the implementation that has caused various bugs over the years.

The solution was to make it stringify like a normal anonymous typeglob, like those produced by open($foo->{bar}, ...) [perl #96326].

Deprecations ^

Don't read the Unicode data base files in lib/unicore

It is now deprecated to directly read the Unicode data base files. These are stored in the lib/unicore directory. Instead, you should use the new functions in Unicode::UCD. These provide a stable API, and give complete information. (This API is, however, subject to change somewhat during the 5.15 development cycle, as we gain experience and get feedback from using it.)

Perl may at some point in the future change or remove the files. The file most likely for applications to have used is lib/unicore/ "prop_invmap()" in Unicode::UCD can be used to get at its data instead.

Performance Enhancements ^

Modules and Pragmata ^

New Modules and Pragmata

Updated Modules and Pragmata

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 Errors

New Warnings

Changes to Existing Diagnostics

Configuration and Compilation ^

Platform Support ^

Platform-Specific Notes


Numerous build and test failures on GNU/Hurd have been resolved with hints for building DBM modules, detection of the library search path, and enabling of large file support.


Perl is now built with dynamic linking on OpenVOS, the minimum supported version of which is now Release 17.1.0.


The CC workshop C++ compiler is now detected and used on systems that ship without cc.

Internal Changes ^

Selected Bug Fixes ^

Acknowledgements ^

Perl 5.15.5 represents approximately 1 month of development since Perl 5.15.4 and contains approximately 28,000 lines of changes across 440 files from 29 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 5.15.5:

Brian Fraser, Chris 'BinGOs' Williams, chromatic, Craig A. Berry, David Golden, Father Chrysostomos, Florian Ragwitz, H.Merijn Brand, Jilles Tjoelker, Jim Meyering, Karl Williamson, Laurent Dami, Leon Timmermans, Mark A. Stratman, Matthew Horsfall, Michael G Schwern, Moritz Lenz, Nicholas Clark, Paul Evans, Paul Green, Paul Johnson, Perlover, Pino Toscano, Reini Urban, Steve Hay, Tom Christiansen, Tony Cook, Vincent Pit, 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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