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Changes for version 5.26.0

  • =head1 Core Enhancements
  • =head2 New regular expression modifier C</xx>
  • Specifying two C<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 S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at L<perlre/E<sol>x and E<sol>xx>.
  • =head2 New Hash Function For 64-bit Builds
  • We have switched to a hybrid hash function to better balance performance for short and long keys.
  • For short keys, 16 bytes and under, we use an optimised variant of One At A Time Hard, and for longer keys we use Siphash 1-3. For very long keys this is a big improvement in performance. For shorter keys there is a modest improvement.
  • =head2 Indented Here-documents
  • This adds a new modifier '~' to here-docs that tells the parser that it should look for /^\s*$DELIM\n/ as the closing delimiter.
  • These syntaxes are all supported:
    • <<~EOF; <<~\EOF; <<~'EOF'; <<~"EOF"; <<~`EOF`; <<~ 'EOF'; <<~ "EOF"; <<~ `EOF`;
  • The '~' modifier will strip, from each line in the here-doc, the same whitespace that appears before the delimiter.
  • Newlines will be copied as is, and lines that don't include the proper beginning whitespace will cause perl to croak.
  • For example:
    • if (1) { print <<~EOF; Hello there EOF }
  • prints "Hello there\n" with no leading whitespace.
  • =head2 '.' and @INC
  • Perl now provides a way to build perl without C<.> in @INC by default. If you want this feature, you can build with -Ddefault_inc_excludes_dot
  • Because the testing / make process for perl modules do not function well with C<.> missing from @INC, Perl now supports the environment variable PERL_USE_UNSAFE_INC=1 which makes Perl behave as it previously did, returning C<.> to @INC in all child processes.
  • WARNING: C<PERL_USE_UNSAFE_INC> has been provided during the perl 5.25 development cycle and is not guaranteed to function in perl 5.26.
  • =head2 create a safer utf8_hop() called utf8_hop_safe()
  • Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after the end of the supplied buffer.
  • =head2 @{^CAPTURE}, %{^CAPTURE}, and %{^CAPTURE_ALL}
  • C<@{^CAPTURE}> exposes the capture buffers of the last match as an array. So C<$1> is C<${^CAPTURE}[0]>.
  • C<%{^CAPTURE}> is the equivalent to C<%+> (ie named captures)
  • C<%{^CAPTURE_ALL}> is the equivalent to C<%-> (ie all named captures).
  • =head2 Unicode 9.0 is now supported
  • A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>. Modules that are shipped with core Perl but not maintained by p5p do not necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
  • =head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
  • Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and called it Script_Extensions (C<scx>). As of now, Perl uses this improved version when a property is specified as just C<\p{I<script>}>. The meaning of compound forms, like C<\p{sc=I<script>}> are unchanged. This should make programs be more accurate when determining if a character is used in a given script, but there is a slight chance of breakage for programs that very specifically needed the old behavior. See L<perlunicode/Scripts>.
  • =head2 Declaring a reference to a variable
  • As an experimental feature, Perl now allows the referencing operator to come after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>, L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must be enabled with C<use feature 'declared_refs'>. It is experimental, and will warn by default unless C<no warnings 'experimental::refaliasing'> is in effect. It is intended mainly for use in assignments to references. For example:
    • use experimental 'refaliasing', 'declared_refs'; my \$a = \$b;
  • See L<perlref/Assigning to References> for slightly more detail.
  • =head2 Perl can now do default collation in UTF-8 locales on platforms that support it
  • Some platforms natively do a reasonable job of collating and sorting in UTF-8 locales. Perl now works with those. For portability and full control, L<Unicode::Collate> is still recommended, but now you may not need to do anything special to get good-enough results, depending on your application. See L<perllocale/Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>.
  • =head2 Better locale collation of strings containing embedded C<NUL> characters
  • In locales that have multi-level character weights, these are now ignored at the higher priority ones. There are still some gotchas in some strings, though. See L<perllocale/Collation of strings containing embedded C<NUL> characters>.
  • =head2 Lexical subroutines are no longer experimental
  • Using the C<lexical_subs> feature no longer emits a warning. Existing code that disables the C<experimental::lexical_subs> warning category that the feature previously used will continue to work. The C<lexical_subs> feature has no effect; all Perl code can use lexical subroutines, regardless of what feature declarations are in scope.
  • =head2 C<CORE> subroutines for hash and array functions callable via reference
  • The hash and array functions in the C<CORE> namespace--C<keys>, C<each>, C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>--, can now be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference (C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be used when inlined.
  • =head2 POSIX::tmpnam() has been removed
  • The fundamentally unsafe C<tmpnam()> interface was deprecated in Perl 5.22.0 and has now been removed. In its place you can use for example the L<File::Temp> interfaces.
  • =head2 require ::Foo::Bar is now illegal.
  • Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any bareword require which starts with a double colon dies instead.
  • =head2 Unescaped literal C<"{"> characters in regular expression patterns are no longer permissible
  • You have to now say something like C<"\{"> or C<"[{]"> 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 C<"{"> is the first character in the pattern.
  • These have been deprecated since v5.16, with a deprecation message displayed starting in v5.22.
  • =head2 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

Documentation

README for the Porting/ directory in the Perl 5 core distribution.
Compare the performance of perl code snippets across multiple perls.
use git bisect to pinpoint changes
Check that all the URLs in the Perl source are valid
Check source code for ANSI-C violations
list of Perl release epigraphs
expand C macros using the C preprocessor
Annotate commits for perldelta
How to write a perldelta
Notes on handling the Perl Patch Pumpkin And Porting Perl
Releasing a new version of perl 5.x
Perl 5 release schedule
Sort warning and error messages in perldiag.pod
Perl TO-DO list
A post processor for make test.valgrind
autogenerated documentation for the perl public API
access Perl configuration information
lib
manipulate @INC at compile time
Dynamically load C libraries into Perl code
System errno constants
Group Perl's functions a la perlfunc.pod
Test Pod::Functions
convert .pod files to .html files
Test Pod::Html::anchorify()
the
Test HTML cross reference links
Test --htmldir feature
Test --htmldir feature
Test --htmldir feature
Test --htmldir feature
Test --htmldir feature
Test HTML links
Plain Old Documentation: format specification and notes
Perl predefined variables
converts a collection of POD pages to HTML format.
Namespace for Perl's core routines
Reserved special namespace for internals related functions
The tests for Pod::InputObjects
Tests for Pod::Select.
Tests for Pod::Usage
the perl debugger
make patchnum
distribute ppport.h among extensions
The Perl 5 language interpreter
what's new for perl5.004
what's new for perl5.005
what is new for perl 5.10.0
what is new for perl v5.10.1
what is new for perl v5.12.0
what is new for perl v5.12.1
what is new for perl v5.12.2
what is new for perl v5.12.3
what is new for perl v5.12.4
what is new for perl v5.12.5
what is new for perl v5.14.0
what is new for perl v5.14.1
what is new for perl v5.14.2
what is new for perl v5.14.3
what is new for perl v5.14.4
what is new for perl v5.16.0
what is new for perl v5.16.1
what is new for perl v5.16.2
what is new for perl v5.16.3
what is new for perl v5.18.0
what is new for perl v5.18.1
what is new for perl v5.18.2
what is new for perl v5.18.4
what is new for perl v5.20.0
what is new for perl v5.20.1
what is new for perl v5.20.2
what is new for perl v5.20.3
what is new for perl v5.22.0
what is new for perl v5.22.1
what is new for perl v5.22.2
what is new for perl v5.22.3
what is new for perl v5.24.0
what is new for perl v5.24.1
what is new for perl v5.25.10
what is new for perl v5.25.11
what is new for perl v5.25.12
what is new for perl v5.25.1
what is new for perl v5.25.2
what is new for perl v5.25.3
what is new for perl v5.25.4
what is new for perl v5.25.5
what is new for perl v5.25.6
what is new for perl v5.25.7
what is new for perl v5.25.8
what is new for perl v5.25.9
what's new for perl v5.6.1
what's new for perl v5.6.0
what is new for perl v5.8.1
what is new for perl v5.8.2
what is new for perl v5.8.3
what is new for perl v5.8.4
what is new for perl v5.8.5
what is new for perl v5.8.6
what is new for perl v5.8.7
what is new for perl v5.8.8
what is new for perl v5.8.9
what is new for perl v5.8.0
perl's IO abstraction interface.
the Perl Artistic License
Books about and related to Perl
Links to information on object-oriented programming in Perl
Links to information on object-oriented programming in Perl
Perl calling conventions from C
Perl 5 Cheat Sheet
Internal replacements for standard C library functions
a brief overview of the Perl community
Perl data types
Perl DBM Filters
Guts of Perl debugging
Perl debugging tutorial
Perl debugging
what is new for perl v5.26.0
list Perl deprecations
various Perl diagnostics
Perl Data Structures Cookbook
Perl's support for DTrace
Considerations for running Perl on EBCDIC platforms
how to embed perl in your C program
A listing of experimental features in Perl
Source Filters
Perl's fork() emulation
Perl formats
Perl builtin functions
Detailed information about git and the Perl repository
the GNU General Public License, version 1
Introduction to the Perl API
How to hack on Perl
Tips for Perl core C code hacking
Walk through the creation of a simple C code patch
the Perl history records
An overview of the Perl interpreter
a brief introduction and overview of Perl
C API for Perl's implementation of IO in Layers.
Perl interprocess communication (signals, fifos, pipes, safe subprocesses, sockets, and semaphores)
Perl Lexical Warnings
Perl locale handling (internationalization and localization)
Manipulating Arrays of Arrays in Perl
Perl modules (packages and symbol tables)
Installing CPAN Modules
constructing new Perl modules and finding existing ones
Perl module style guide
Perl method resolution plugin interface
preparing a new module for distribution
semantics of numbers and numeric operations in Perl
Perl object reference
Object-Oriented Programming in Perl Tutorial
Perl operators and precedence
simple recipes for opening files and pipes in Perl
tutorial on pack and unpack
Perl Performance and Optimization Techniques
the Plain Old Documentation format
Plain Old Documentation: format specification and notes
Perl POD style guide
Various and sundry policies and commitments related to the Perl core
Writing portable Perl
how to write a user pragma
Perl regular expressions
Perl regular expression plugin interface
Perl Regular Expression Backslash Sequences and Escapes
Perl Regular Expression Character Classes
Perl references and nested data structures
Mark's very short tutorial about references
Description of the Perl regular expression engine.
Links to current information on the Perl source repository
Perl regular expressions quick start
Perl Regular Expressions Reference
Perl regular expressions tutorial
how to execute the Perl interpreter
Perl security
A guide to the Perl source tree
Perl style guide
Perl subroutines
Perl syntax
Tutorial on threads in Perl
how to hide an object class in a simple variable
Link to the Perl to-do list
Links to information on object-oriented programming in Perl
Links to information on object-oriented programming in Perl
Perl traps for the unwary
Unicode support in Perl
cookbookish examples of handling Unicode in Perl
Perl Unicode FAQ
Perl Unicode introduction
Perl Unicode Tutorial
utilities packaged with the Perl distribution
Perl predefined variables
VMS-specific documentation for Perl
Perl pragma to enable new features
Generate C macros that match character classes efficiently
Perl pragma to control optional warnings
a C++ base class encapsulating a Perl interpreter in Symbian
a C++ utility class for Perl/Symbian
convert .h C header files to .ph Perl header files
convert .h C header files to Perl extensions
configure libnet
how to submit bug reports on Perl
Perl Installation Verification Procedure
Rough tool to translate Perl4 .pl files to Perl5 .pm modules.

Modules

functions for dealing with RFC3066-style language tags
detect the user's language preferences
tags and names for human languages
IO
load various IO modules
supply object methods for directory handles
supply object methods for filehandles
supply object methods for I/O handles
supply object methods for pipes
Object interface to system poll call
supply seek based methods for I/O objects
OO interface to the select system call
Object interface to socket communications
Object interface for AF_INET domain sockets
Object interface for AF_UNIX domain sockets
Perl extension for ARexx support
Perl extension for low level amiga support
B
The Perl Compiler Backend
Walk Perl syntax tree, printing concise info about ops
Show lexical variables used in functions or files
Walk Perl syntax tree, printing terse info about ops
Generates cross reference reports for Perl programs
O
Generic interface to Perl Compiler backends
check optrees as rendered by B::Concise
A data debugging tool for the XS programmer
write the C code for miniperlmain.c and perlmain.c
load the C Fcntl.h defines
DOS like globbing and then some
Traverse a directory tree.
Perl extension for BSD glob routine
keep more files open than the system permits
Perl5 access to the gdbm library.
Support for Inside-Out Classes
A selection of general-utility hash subroutines
query locale information
open a process for both reading and writing using open2()
open a process for reading, writing, and error handling using open3()
Tied access to ndbm files
Tied access to odbm files
Disable named opcodes when compiling perl code
ops
Perl pragma to restrict unsafe operations when compiling
Perl interface to IEEE Std 1003.1
encoding layer
Memory mapped IO
in-memory IO, scalar IO
Helper class for PerlIO layers implemented in perl
module to convert pod files to HTML
Tied access to sdbm files
Try every conceivable way to get hostname
Named regexp capture buffers
add data to hash when needed
Perl extension to manipulate DCL symbols
convert between VMS and Unix file specification syntax
standard I/O functions via VMS extensions
Win32 CORE function stubs
Test the perl C API
module to test the XS typemaps distributed with perl
Set indexing base via $[
get/set subroutine or variable attributes
mro
Method Resolution Order
re
Perl pragma to alter regular expression behaviour
Interfaces to some Haiku API Functions
provide framework for multiple DBMs
Perl compiler backend to produce perl code
OP op_private flag definitions
benchmark running times of Perl code
declare struct-like datatypes as Perl classes
hash lookup of which core extensions were built.
DB
programmatic interface to the Perl debugging API
Filter DBM keys/values
filter for DBM_Filter
filter for DBM_Filter
filter for DBM_Filter
filter for DBM_Filter
filter for DBM_Filter
supply object methods for directory handles
use nice English (or awk) names for ugly punctuation variables
Utilities for embedding Perl in C/C++ applications
keep sets of symbol names palatable to the VMS linker
Parse file paths into directory, filename and suffix.
Compare files or filehandles
Copy files or filehandles
by-name interface to Perl's built-in stat() functions
supply object methods for filehandles
Locate directory of original perl script
Process single-character switches with switch clustering
by-name interface to Perl's built-in gethost*() functions
by-name interface to Perl's built-in getnet*() functions
by-name interface to Perl's built-in getproto*() functions
by-name interface to Perl's built-in getserv*() functions
On demand loader for PerlIO layers and root of PerlIO::* name space
save and restore selected file handle
manipulate Perl symbols and their names
Manipulate threads in Perl (for old code only)
base class for tied arrays
base class definitions for tied handles
base class definitions for tied handles
Fixed-table-size, fixed-key-length hashing
by-name interface to Perl's built-in gmtime() function
by-name interface to Perl's built-in localtime() function
internal object used by Time::gmtime and Time::localtime
base class for ALL classes (blessed references)
Unicode character database
by-name interface to Perl's built-in getgr*() functions
by-name interface to Perl's built-in getpw*() functions
Use MakeMaker's uninstalled version of a package
Perl pragma to expose the individual bytes of characters
access to Unicode character names and named character sequences; also define character names
Perl pragma for deprecating the core version of a module
Perl pragma to enable new features
Perl pragma to control the filetest permission operators
Perl pragma to use integer arithmetic instead of floating point
perl pragma to request less of something
Perl pragma to use or avoid POSIX locales for built-in operations
perl pragma to set default PerlIO layers for input and output
Package for overloading Perl operations
perl pragma to lexically control overloading
Perl pragma to enable simple signal handling
perl pragma to control sort() behaviour
Perl pragma to restrict unsafe constructs
Perl pragma to predeclare sub names
Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
Perl pragma to predeclare global variable names
Perl pragma to control VMS-specific language features
Perl pragma to control optional warnings
warnings import function
Perl access to extended attributes.
Perl extension for access to OS/2 setting database.
exports constants for system() call, and process control on OS2.
access to DLLs with REXX calling convention.
access to DLLs with REXX calling convention and REXX runtime.

Provides

in ext/Amiga-ARexx/ARexx.pm
in ext/B/B.pm
in lib/Class/Struct.pm
in symbian/ext/Moped/Msg/Msg.pm
in os2/OS2/OS2-REXX/DLL/DLL.pm
in os2/OS2/OS2-PrfDB/PrfDB.pm
in os2/OS2/OS2-PrfDB/PrfDB.pm
in os2/OS2/OS2-REXX/REXX.pm
in os2/OS2/OS2-REXX/REXX.pm
in os2/OS2/OS2-REXX/REXX.pm
in os2/OS2/OS2-Process/Process.pm
in ext/POSIX/lib/POSIX.pm
in ext/POSIX/lib/POSIX.pm
in ext/POSIX/lib/POSIX.pm
in ext/Pod-Html/lib/Pod/Html.pm
in ext/File-Find/t/lib/Testing.pm
in lib/Tie/Hash.pm
in lib/DBM_Filter.pm
in lib/Tie/Hash.pm
in lib/Tie/Scalar.pm
in lib/Tie/Array.pm
in lib/Tie/Hash.pm
in lib/Tie/Scalar.pm
in ext/VMS-Stdio/Stdio.pm
in lib/diagnostics.pm
in lib/overload/numbers.pm
in ext/XS-APItest/t/BHK.pm
in ext/XS-APItest/t/Markers.pm