Man1 - perldelta.1perl

An initial experimental attempt at providing try=/=catch notation has been added.

use feature try; try { a_function(); } catch ($e) { warn “An error occurred: $e”; }

For more information, see Try Catch Exception Handling in perlsyn.

An empty lower bound is now accepted for regular expression quantifiers, like {,3}.

(in double-quotish contexts and regular expression patterns)

This means you can write things like \x{ FFFC } if you like. This applies to all such constructs, namely \b{}, \g{}, \k{}, \N{}, \o{}, and \x{}; as well as the regular expression quantifier {=/=m=/,=/=n=/=}=. \p{} and \P{} retain their already-existing, even looser, rules mandated by the Unicode standard (see Properties accessible through \p{} and \P{} in perluniprops).

This ability is in effect regardless of the presence of the /x regular expression pattern modifier.

Additionally, the comma in a regular expression braced quantifier may have blanks (tabs or spaces) before and/or after the comma, like qr/a{ 5, 7 }/.

It is now possible to specify octal literals with 0o prefixes, as in 0o123_456, parallel to the existing construct to specify hexadecimal literal 0x=/=ddddd=/ and binary literal =0b=/=ddddd=/. Also, the builtin =oct() function now accepts this new syntax.

See Scalar value constructors in perldata and oct EXPR in perlfunc.

• ExtUtils::PL2Bat 0.004 has been added to the Perl core. This module is a generalization of the pl2bat script. It being a script has led to at least two forks of this code; this module will unify them under one implementation with tests.

• Archive::Tar has been upgraded from version 2.36 to 2.38.
• autodie has been upgraded from version 2.32 to 2.34.
• B has been upgraded from version 1.80 to 1.82.
• B::Deparse has been upgraded from version 1.54 to 1.56.
• bytes has been upgraded from version 1.07 to 1.08.
• Carp has been upgraded from version 1.50 to 1.52.
• Compress::Raw::Bzip2 has been upgraded from version 2.093 to 2.101.
• Compress::Raw::Zlib has been upgraded from version 2.093 to 2.101.
• Config::Perl::V has been upgraded from version 0.32 to 0.33.
• CPAN has been upgraded from version 2.27 to 2.28.
• Data::Dumper has been upgraded from version 2.174 to 2.179.
• DB has been upgraded from version 1.58 to 1.59.
• DB_File has been upgraded from version 1.853 to 1.855.
• Devel::Peek has been upgraded from version 1.28 to 1.30.
• Devel::PPPort has been upgraded from version 3.57 to 3.62. New PERL_VERSION_* comparison macros are now available. ppport.h --api-info no longer includes non-API info unless that is the only match
• Digest has been upgraded from version 1.17_01 to 1.19.
• Digest::MD5 has been upgraded from version 2.55_01 to 2.58.
• DynaLoader has been upgraded from version 1.47 to 1.50.
• Encode has been upgraded from version 3.06 to 3.08.
• Env has been upgraded from version 1.04 to 1.05.
• Errno has been upgraded from version 1.30 to 1.33.
• experimental has been upgraded from version 0.020 to 0.024.
• Exporter has been upgraded from version 5.74 to 5.76.
• ExtUtils::CBuilder has been upgraded from version 0.280234 to 0.280236.
• ExtUtils::Install has been upgraded from version 2.14 to 2.20.
• ExtUtils::MakeMaker has been upgraded from version 7.44 to 7.62.
• ExtUtils::Manifest has been upgraded from version 1.72 to 1.73.
• ExtUtils::Miniperl has been upgraded from version 1.09 to 1.10.
• ExtUtils::ParseXS has been upgraded from version 3.40 to 3.43.
• ExtUtils::Typemaps has been upgraded from version 3.38 to 3.43.
• Fcntl has been upgraded from version 1.13 to 1.14.
• feature has been upgraded from version 1.58 to 1.64. Added the default enabled bareword_filehandles feature. A new multidimensional feature has been added, which is enabled by default but allows turning off multi-dimensional array emulation.
• :Copy has been upgraded from version 2.34 to 2.35.
• :Fetch has been upgraded from version 0.56 to 1.00.
• :Find has been upgraded from version 1.37 to 1.39.
• :Path has been upgraded from version 2.16 to 2.18.
• :Spec has been upgraded from version 3.78 to 3.80.
• :Temp has been upgraded from version 0.2309 to 0.2311.
• Filter::Util::Call has been upgraded from version 1.59 to 1.60.
• FindBin has been upgraded from version 1.51 to 1.52.
• GDBM_File has been upgraded from version 1.18 to 1.19. New functions and compatibility for newer versions of GDBM. [GH #18435 https://github.com/Perl/perl5/pull/18435]
• Getopt::Long has been upgraded from version 2.51 to 2.52.
• Getopt::Std has been upgraded from version 1.12 to 1.13.
• Hash::Util has been upgraded from version 0.23 to 0.25.
• Hash::Util::FieldHash has been upgraded from version 1.20 to 1.21.
• I18N::LangTags has been upgraded from version 0.44 to 0.45.
• if has been upgraded from version 0.0608 to 0.0609.
• IO has been upgraded from version 1.43 to 1.46. IO::Socket now stores error messages in $IO::Socket::errstr, in addition to in $@. The error method now reports the error state for both the input and output streams for sockets and character devices. Similarly clearerr now clears the error state for both streams. A spurious error reported for regular file handles has been fixed in IO::Handle. [GH #18019 https://github.com/Perl/perl5/issues/18019]
• IO-Compress has been upgraded from version 2.093 to 2.102. bin/zipdetails version 2.02
• IO::Socket::IP has been upgraded from version 0.39 to 0.41.
• IO::Zlib has been upgraded from version 1.10 to 1.11.
• IPC::SysV has been upgraded from version 2.07 to 2.09.
• JSON::PP has been upgraded from version 4.04 to 4.06.
• The libnet distribution has been upgraded from version 3.11 to 3.13.
• locale has been upgraded from version 1.09 to 1.10.
• Math::Complex has been upgraded from version 1.5901 to 1.5902.
• MIME::Base64 has been upgraded from version 3.15 to 3.16.
• Module::CoreList has been upgraded from version 5.20200620 to 5.20210520.
• Module::Load has been upgraded from version 0.34 to 0.36.
• Module::Load::Conditional has been upgraded from version 0.70 to 0.74.
• mro has been upgraded from version 1.23 to 1.25_001.
• Net::Ping has been upgraded from version 2.72 to 2.74.
• NEXT has been upgraded from version 0.67_01 to 0.68.
• ODBM_File has been upgraded from version 1.16 to 1.17.
• Opcode has been upgraded from version 1.47 to 1.50.
• overload has been upgraded from version 1.31 to 1.33.
• perlfaq has been upgraded from version 5.20200523 to 5.20210411.
• PerlIO::encoding has been upgraded from version 0.28 to 0.30.
• PerlIO::mmap has been upgraded from version 0.016 to 0.017.
• PerlIO::scalar has been upgraded from version 0.30 to 0.31.
• PerlIO::via::QuotedPrint has been upgraded from version 0.08 to 0.09.
• Pod::Checker has been upgraded from version 1.73 to 1.74.
• Pod::Html has been upgraded from version 1.25 to 1.27.
• Pod::Simple has been upgraded from version 3.40 to 3.42.
• Pod::Usage has been upgraded from version 1.69 to 2.01.
• POSIX has been upgraded from version 1.94 to 1.97. POSIX::signbit() behaviour has been improved. [GH #18441 https://github.com/Perl/perl5/pull/18441] Documentation for asctime clarifies that the result is always in English. (Use strftime for a localized result.)
• re has been upgraded from version 0.40 to 0.41. (See under Internal Changes for more information.)
• Safe has been upgraded from version 2.41 to 2.43.
• Socket has been upgraded from version 2.029 to 2.031.
• Storable has been upgraded from version 3.21 to 3.23.
• strict has been upgraded from version 1.11 to 1.12.
• subs has been upgraded from version 1.03 to 1.04.
• Symbol has been upgraded from version 1.08 to 1.09.
• Test::Harness has been upgraded from version 3.42 to 3.43.
• Test::Simple has been upgraded from version 1.302175 to 1.302183.
• Text::Balanced has been upgraded from version 2.03 to 2.04.
• threads has been upgraded from version 2.25 to 2.26.
• threads::shared has been upgraded from version 1.61 to 1.62.
• Tie::RefHash has been upgraded from version 1.39 to 1.40.
• Time::HiRes has been upgraded from version 1.9764 to 1.9767.
• Time::Local has been upgraded from version 1.28 to 1.30.
• Unicode::Collate has been upgraded from version 1.27 to 1.29.
• Unicode::Normalize has been upgraded from version 1.27 to 1.28.
• utf8 has been upgraded from version 1.22 to 1.24.
• version has been upgraded from version 0.9924 to 0.9928.
• warnings has been upgraded from version 1.47 to 1.51.
• Win32 has been upgraded from version 0.53 to 0.57. Fix calling convention for PFNRegGetValueA. Added Win32::IsSymlinkCreationAllowed(), Win32::IsDeveloperModeEnabled(), and Win32::GetProcessPrivileges(). Removed old code for versions before Windows 2000.
• XS::APItest has been upgraded from version 1.09 to 1.16.
• XS::Typemap has been upgraded from version 0.17 to 0.18.

perldocstyle

This document is a guide for the authorship and maintenance of the documentation that ships with Perl.

perlgov

This document describes the goals, scope, system, and rules for Perl’s new governance model.

Other pod files, most notably perlpolicy, were amended to reflect its adoption.

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.

Additionally, the following selected changes have been made:

• perlapi, perlguts, perlxs, and perlxstut now prefer SvPVbyte over SvPV.
• References to Pumpking have been replaced with a more accurate term or Steering Council where appropriate.
• The Perl Steering Council is now the fallback contact for security issues.

perlapi

• Efforts continue in improving the presentation of this document, and to document more API elements.

perlcommunity

• The freenode IRC URL has been updated.

perldebguts

• Corrected the description of the scalar ${"_<$filename"} variables.

perldiag

• Now documents additional examples of not imported warnings.

perlfaq

• The Perl FAQ was updated to CPAN version 5.20201107 with minor improvements.

perlfunc

• my() and state() now explicitly warn the reader that lexical variables should typically not be redeclared within the same scope or statement. [GH #18389 https://github.com/Perl/perl5/issues/18389]
• The localtime entry has been improved and now also states that the result of the function is always in English.
• msgsnd() documented a length field included in the packed MSG parameter to msgsnd(), but there was no such field. MSG contains only the type and the message content.
• Better explanation of what happens when sleep is called with a zero or negative value.
• Simplify the split() documentation by removing the =join()=s from the examples [GH #18676 https://github.com/Perl/perl5/issues/18676]

perlgit

• document how to create a remote-tracking branch for every PR
• document how to get a PR as a local branch

perlguts

• perlguts now explains in greater detail the need to consult SvUTF8 when calling SvPV (or variants). A new How do I pass a Perl string to a C library? section in the same document discusses when to use which style of macro to read an SV’s string value.
• Corrected my_rpeep example in perlguts.
• A section has been added on the formatted printing of special sizes.

perlop

• The <> and <<>> operators are commonly referred to as the diamond and double diamond operators respectively, but that wasn’t mentioned previously in their documentation.
• Document range op behavior change.

perlpacktut

• Incorrect variables used in an example have been fixed.

perlsyn

• Document that caller() does not see try{} blocks
• A new example shows how a lexical my variable can be declared during the initialization of a for loop.

perlunifaq

• Fix description of what Perl does with unencoded strings

New Errors

• Bareword filehandle %s not allowed under ’no feature bareword_filehandles’ This accompanies the new bareword_filehandles feature.
• Multidimensional hash lookup is disabled This accompanies the new multidimensional feature.

New Warnings

• Wide character in setenv key (encoding to utf8) Attempts to put wide characters into environment variable keys via %ENV now provoke this warning.

• Error %s in expansion of %s An error was encountered in handling a user-defined property (User-Defined Character Properties in perlunicode). These are programmer written subroutines, hence subject to errors that may prevent them from compiling or running.
• Infinite recursion in user-defined property A user-defined property (User-Defined Character Properties in perlunicode) can depend on the definitions of other user-defined properties. If the chain of dependencies leads back to this property, infinite recursion would occur, were it not for the check that raised this error.
• Timeout waiting for another thread to define \p{%s} The first time a user-defined property (User-Defined Character Properties in perlunicode) is used, its definition is looked up and converted into an internal form for more efficient handling in subsequent uses. There could be a race if two or more threads tried to do this processing nearly simultaneously.
• Unknown user-defined property name \p{%s} You specified to use a property within the \p{...} which was a syntactically valid user-defined property, but no definition was found for it
• Too few arguments for subroutine ’%s’ (got %d; expected %d) Subroutine argument-count mismatch errors now include the number of given and expected arguments.
• Too many arguments for subroutine ’%s’ (got %d; expected %d) Subroutine argument-count mismatch errors now include the number of given and expected arguments.
• Lost precision when %s %f by 1 This warning was only issued for positive too-large values when incrementing, and only for negative ones when decrementing. It is now issued for both positive or negative too-large values. [GH #18333 https://github.com/Perl/perl5/issues/18333]
• \K not permitted in lookahead/lookbehind in regex; marked by <– HERE in m/%s/ This error was incorrectly produced in some cases involving nested lookarounds. This has been fixed. [GH #18123 https://github.com/Perl/perl5/issues/18123]
• Use of uninitialized value%s This warning may now include the array or hash index when the uninitialized value is the result of an element not found. This will only happen if the index is a simple non-magical variable.

• New option: HistItemMinLength This option controls the minimum length a command must be to get stored in history. Traditionally, this has been fixed at 2. Changes to the debugger are often perilous, and new bugs should be reported so the debugger can be debugged.
• Fix to i and l commands The i $var and l $var commands work again with lexical variables.

9front

Allow building Perl on i386 9front systems (a fork of plan9).

Plan9

Improve support for Plan9 on i386 platforms.

MacOS (Darwin)

The hints file for darwin has been updated to handle future MacOS versions beyond 10. [GH #17946 https://github.com/Perl/perl5/issues/17946]

Symbian

Support code relating to Symbian has been removed. Symbian was an operating system for mobile devices. The port was last updated in July 2009, and the platform itself in October 2012.

DragonFlyBSD

Tests were updated to workaround DragonFlyBSD bugs in tc*() functions https://bugs.dragonflybsd.org/issues/3252 and ctime updates https://bugs.dragonflybsd.org/issues/3251.

Mac OS X

A number of system libraries no longer exist as actual files on Big Sur, even though dlopen will pretend they do, so now we fall back to dlopen if a library file can not be found. [GH #18407 https://github.com/Perl/perl5/issues/18407]

Windows

Reading non-ASCII characters from the console when its codepage was set to 65001 (UTF-8) was broken due to a bug in Windows. A workaround for this problem has been implemented. [GH #18701 https://github.com/Perl/perl5/issues/18701] Building with mingw.org compilers (version 3.4.5 or later) using mingw runtime versions < 3.22 now works again. This was broken in Perl 5.31.4. Building with mingw.org compilers (version 3.4.5 or later) using mingw runtime versions >= 3.21 now works (for compilers up to version 5.3.0). Makefile.mk, and thus support for dmake, has been removed. It is still possible to build Perl on Windows using nmake (Makefile) and GNU make (GNUmakefile). [GH #18511 https://github.com/Perl/perl5/pull/18511] perl can now be built with USE_QUADMATH on MS Windows using (32-bit and 64-bit) mingw-w64 ports of gcc. [GH #18465 https://github.com/Perl/perl5/pull/18465] The pl2bat.pl utility now needs to use ExtUtils::PL2Bat. This could cause failures in parallel builds. Windows now supports symlink() and readlink(), and lstat() is no longer an alias for stat(). [GH #18005 https://github.com/Perl/perl5/issues/18005]. Unlike POSIX systems, creating a symbolic link on Windows requires either elevated privileges or Windows 10 1703 or later with Developer Mode enabled. stat(), including stat FILEHANDLE, and lstat() now uses our own implementation that populates the device dev and inode numbers ino returned rather than always returning zero. The number of links nlink field is now always populated. ${^WIN32_SLOPPY_STAT} previously controlled whether the nlink field was populated requiring a separate Windows API call to fetch, since nlink and the other information required for stat() is now retrieved in a single API call. The -r and -w operators now return true for the STDIN, STDOUT and STDERR handles. Unfortunately it still won’t return true for duplicates of those handles. [GH #8502 https://github.com/Perl/perl5/issues/8502]. The times returned by stat() and lstat() are no longer incorrect across Daylight Savings Time adjustments. [GH #6080 https://github.com/Perl/perl5/issues/6080]. -x on a filehandle should now match -x on the corresponding filename on Vista or later. [GH #4145 https://github.com/Perl/perl5/issues/4145]. -e " no longer incorrectly returns true. [GH #12431 https://github.com/Perl/perl5/issues/12431]. The same manifest is now used for Visual C++ and gcc builds. Previously, MSVC builds were using the /manifestdependency flag instead of embedding perlexe.manifest, which caused issues such as GetVersionEx() returning the wrong version number on Windows 10.

z/OS

The locale categories LC_SYNTAX and LC_TOD are now recognized. Perl doesn’t do anything with these, except it now allows you to specify them. They are included in LC_ALL.