perldelta - what is new for perl v5.35.10
This document describes differences between the 5.35.9 release and the 5.35.10 release.
If you are upgrading from an earlier release such as 5.35.8, first read perl5359delta, which describes differences between 5.35.8 and 5.35.9.
builtin::trim
This function treats its argument as a string, returning the result of removing all white space at its beginning and ending. See "trim" in builtin
Prior to this release any form of variable length lookbehind was considered experimental. With this release the experimental status has been reduced to cover only lookbehind that contains capturing parenthesis. This is because it is not clear if
"aaz"=~/(?=z)(?<=(a|aa))/
should match and leave $1 equaling "a" or "aa". Currently it will match the longest possible alternative, "aa". We are confident that the overall construct will now match only when it should, we are not confident that we will keep the current "longest match" behavior.
A new function has been added to the builtin package, called indexed. It returns a list twice as big as its argument list, where each item is preceded by its index within that list. This is primarily useful for using the new foreach syntax with multiple iterator variables to iterate over an array or list, while also tracking the index of each item:
builtin
indexed
foreach
use builtin 'indexed'; foreach my ($index, $val) (indexed @array) { ... }
Perl traditionally has allowed just four pairs of string/pattern delimiters: ( ) { } [ ] and < >, all in the ASCII range. Unicode has hundreds more possibilities, and using this feature enables many of them. When enabled, you can say qr« » for example, or use utf8; <q𝄃string𝄂. See "The 'extra_paired_delimiters' feature" in feature for details.
( )
{ }
[ ]
< >
qr« »
use utf8; <q𝄃string𝄂
Large hashes no longer allocate their keys from the shared string table.
The same internal datatype (PVHV) is used for all of
PVHV
Symbol tables
Objects (by default)
Associative arrays
The shared string table was originally added to improve performance for blessed hashes used as objects, because every object instance has the same keys, so it is an optimisation to share memory between them. It also makes sense for symbol tables, where derived classes will have the same keys (typically method names), and the OP trees built for method calls can also share memory. The shared string table behaves roughly like a cache for hash keys.
But for hashes actually used as associative arrays - mapping keys to values - typically the keys are not re-used in other hashes. For example, "seen" hashes are keyed by object IDs (or addresses), and logically these keys won't repeat in other hashes.
Storing these "used just once" keys in the shared string table increases CPU and RAM use for no gain. For such keys the shared string table behaves as a cache with a 0% hit rate. Storing all the keys there increases the total size of the shared string table, as well as increasing the number of times it is resized as it grows. Worse - in any environment that has "copy on write" memory for child process (such as a pre-forking server), the memory pages used for the shared string table rapidly need to be copied as the child process manipulates hashes. Hence if most of the shared string table is such keys that are used only in one place, there is no benefit from re-use within the perl interpreter, but a high cost due to more pages for the OS to copy.
The perl interpreter now disables shared hash keys for "large" hashes (that are neither objects nor symbol tables). "Large" is a heuristic - currently the heuristic is that sharing is disabled when adding a key to a hash triggers allocation of more storage, and the hash has more than 42 keys.
This might cause slightly increased memory usage for programs that create (unblessed) data structures that contain multiple large hashes that share the same keys. But generally our testing suggests that for the specific cases described it is a win, and other code is unaffected.
Attribute::Handlers has been upgraded from version 1.01 to 1.02.
B::Deparse has been upgraded from version 1.62 to 1.63.
DB_File has been upgraded from version 1.856 to 1.857.
Devel::PPPort has been upgraded from version 3.64 to 3.68.
experimental has been upgraded from version 0.027 to 0.028.
ExtUtils::ParseXS has been upgraded from version 3.44 to 3.45.
ExtUtils::Typemaps has been upgraded from version 3.44 to 3.45.
feature has been upgraded from version 1.70 to 1.71.
File::Spec has been upgraded from version 3.83 to 3.84.
GDBM_File has been upgraded from version 1.22 to 1.23.
Module::CoreList has been upgraded from version 5.20220220 to 5.20220320.
Opcode has been upgraded from version 1.56 to 1.57.
Scalar::Util has been upgraded from version 1.61 to 1.62.
Test::Simple has been upgraded from version 1.302188 to 1.302190.
warnings has been upgraded from version 1.57 to 1.58.
XS::APItest has been upgraded from version 1.21 to 1.22.
We have attempted to update the documentation to reflect the changes listed in this document. If you find any we have missed, open an issue at https://github.com/Perl/perl5/issues.
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.
Wide character in $0
Attempts to put wide characters into the program name ($0) now provoke this warning.
$0
New 'scalar' category for "Useless use of sort in scalar context"
When sort is used in scalar context, it provokes a warning that this is not useful. This warning used to be in the void category. A new category for warnings about scalar context has now been added, called scalar.
sort
void
scalar
sv_dump (and Devel::Peek’s Dump function) now escapes high-bit octets in the PV as hex rather than octal. Since most folks understand hex more readily than octal, this should make these dumps a bit more legible. This does not affect any other diagnostic interfaces like pv_display.
sv_dump
Dump
pv_display
Perl 5.35.10 represents approximately 4 weeks of development since Perl 5.35.9 and contains approximately 15,000 lines of changes across 300 files from 26 authors.
Excluding auto-generated files, documentation and release tools, there were approximately 6,900 lines of changes to 190 .pm, .t, .c and .h files.
Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.35.10:
Bernd, Brad Barden, Chad Granum, cuishuang, Curtis Poe, Dagfinn Ilmari Mannsåker, Daniel Laügt, Felipe Gasper, Graham Knop, Hugo van der Sanden, James E Keenan, Karl Williamson, Leon Timmermans, Matthew Horsfall, Michiel Beijen, Nicholas Clark, Nicolas R, Paul Evans, Renee Baecker, Ricardo Signes, Richard Leach, Sawyer X, Sisyphus, Steve Hay, TAKAI Kousuke, 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.
If you find what you think is a bug, you might check the perl bug database at https://github.com/Perl/perl5/issues. There may also be information at http://www.perl.org/, the Perl Home Page.
If you believe you have an unreported bug, please open an issue at https://github.com/Perl/perl5/issues. Be sure to trim your bug down to a tiny but sufficient test case.
If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.
If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the perlthanks program:
perlthanks
This will send an email to the Perl 5 Porters list with your show of thanks.
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.
To install utf8, copy and paste the appropriate command in to your terminal.
cpanm
cpanm utf8
CPAN shell
perl -MCPAN -e shell install utf8
For more information on module installation, please visit the detailed CPAN module installation guide.