perl5123delta: Improve description

[perl5.git] / pod / perl5133delta.pod

=encoding utf8

=head1 NAME

perl5133delta - what is new for perl v5.13.3

=head1 DESCRIPTION

This document describes differences between the 5.13.3 release and
the 5.13.2 release.

If you are upgrading from an earlier release such as 5.13.1, first read
L<perl5132delta>, which describes differences between 5.13.1 and
5.13.2.

=head1 Core Enhancements

=head2 \o{...} for octals

There is a new escape sequence, C<"\o">, in double-quote-like contexts.
It must be followed by braces enclosing an octal number of at least one
digit.  It interpolates as the character with an ordinal value equal to
the octal number.  This construct allows large octal ordinals beyond the
current max of 0777 to be represented.  It also allows you to specify a
character in octal which can safely be concatenated with other regex
snippets and which won't be confused with being a backreference to
a regex capture group.  See L<perlre/Capture groups>.

=head2 C<\N{I<name>}> and C<charnames> enhancements

C<\N{}> and C<charnames::vianame> now know about the abbreviated
character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ, etc., as
well as all the customary abbreviations for the C0 and C1 control
characters (such as ACK, BEL, CAN, etc.), as well as a few new variants
in common usage of some C1 full names.

In the past, it was ineffective to override one of Perl's abbreviations
with your own custom alias.  Now it works.

You can also create a custom alias directly to the ordinal of a
character, known by C<\N{...}>, C<charnames::vianame()>, and
C<charnames::viacode()>.  Previously, an alias had to be to an official
Unicode character name.  This made it impossible to create an alias for
a code point that had no name, such as the ones reserved for private
use.  So this change allows you to make more effective use of private
use characters.  Only if there is no official name will
C<charnames::viacode()> return your custom one.

See L<charnames> for details on all these changes.

=head2 Uppercase X/B allowed in hexadecimal/binary literals

Literals may now use either upper case C<0X...> or C<0B...> prefixes,
in addition to the already supported C<0x...> and C<0b...>
syntax. (RT#76296) (a674e8d, 333f87f)

C, Ruby, Python and PHP already supported this syntax, and it makes
Perl more internally consistent. A round-trip with C<eval sprintf
"%#X", 0x10> now returns C<16> in addition to C<eval sprintf "%#x",
0x10>, which worked before.

=head1 Incompatible Changes

=head2 \400 - \777

Use of C<\400> - C<\777> in regexes in certain circumstances has given
different, anomalous behavior than their use in all other
double-quote-like contexts.   Since 5.10.1, a deprecated warning message
has been raised when this happens.  Now, all double-quote-like contexts
have the same behavior, namely to be equivalent to C<\x{100}> -
C<\x{1FF}>, with no deprecation warning. Use of these values in the
command line option C<"-0"> retains the current meaning to slurp input
files whole; previously, this was documented only for C<"-0777">.  It is
recommended, however, because of various ambiguities, to use the new
C<\o{...}> construct to represent characters in octal.
(fa1639c..f6993e9).

=head1 Deprecations

=head2 Omitting a space between a regular expression and subsequent word

Omitting a space between a regex pattern or pattern modifiers and the
following word is deprecated. Deprecation for regular expression
I<matches> was added in Perl 5.13.2.  In this release, the deprecation
is extended to regular expression I<substitutions>. For example,
C<< s/foo/bar/sand $bar >> will still be parsed as
C<< s/foo/bar/s and $bar >> but will issue a warning. (aa78b66)

=head2 Deprecation warning added for deprecated-in-core .pl libs

This is a mandatory warning, not obeying -X or lexical warning bits.
The warning is modelled on that supplied by deprecate.pm for
deprecated-in-core .pm libraries.  It points to the specific CPAN
distribution that contains the .pl libraries. The CPAN version, of
course, does not generate the warning. (0111154)

=head1 Performance Enhancements

There are several small optimizations to reduce CPU cache misses in various very
commonly used modules like C<warnings> and C<Carp> as well in accessing
file-handles for reading.

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item C<autodie>

Upgraded from version 2.06_01 to 2.10.

=item C<charnames>

Upgraded from version 1.08 to 1.10.

C<viacode()> is now significantly faster. (f3227b7)

=item C<lib>

Upgraded from version 0.62 to 0.63.

=item C<threads>

Upgraded from version 1.77_02 to 1.77_03.

=item C<threads::shared>

Upgraded from version 1.33_01 to 1.33_02.

=item C<warnings>

Upgraded from version 1.09 to 1.10.

Calling C<use warnings> without arguments is now significantly more efficient.
(8452af9)

=item C<Archive::Extract>

Upgraded from version 0.38 to 0.42.

Updates since 0.38 include: a safe print method that guards
Archive::Extract from changes to $\; a fix to the tests when run in core
perl; support for TZ files; and a modification for the lzma logic to favour
IO::Uncompress::Unlzma (d7f8799)

=item C<Archive::Tar>

Upgraded from version 1.54 to 1.64.

Important changes since 1.54 include: compatibility with busybox
implementations of tar; a fix so that C<write()> and C<create_archive()>
close only handles they opened; and a bug was fixed regarding the exit code
of extract_archive. (afabe0e)

=item C<Attribute::Handlers>

Upgraded from version 0.87 to 0.88.

=item C<Compress::Raw::Bzip2>

Upgraded from version 2.024 to 2.027.

=item C<Compress::Raw::Zlib>

Upgraded from version 2.024 to 2.027_01.

=item C<Compress::Zlib>

Upgraded from version 2.024 to 2.027.

=item C<CPANPLUS>

Upgraded from version 0.90 to 0.9007.

Fixed the shell test to skip if test is not being run under a terminal;
resolved the issue where a prereq on Config would not be recognised as a
core module. (d4e225a)

=item C<Digest::MD5>

Upgraded from version 2.39 to 2.40.

=item C<Digest::SHA>

Upgraded from version 5.47 to 5.48.

=item C<Exporter>

Upgraded from version 5.64_02 to 5.64_03.

Exporter no longer overrides C<$SIG{__WARN__}> (RT #74472) (9b86bb5)

=item C<ExtUtils::CBuilder>

Upgraded from version 0.27 to 0.2703.

=item C<ExtUtils::Manifest>

Upgraded from version 1.57 to 1.58.

=item C<ExtUtils::ParseXS>

Upgraded from version 2.2205 to 2.2206.

=item C<File::Copy>

Upgraded from version 2.19 to 2.20.

Skips suid tests on a nosuid partition.  These tests were being skipped on
OpenBSD, but nosuid partitions can exist on other systems too. Now it just
checks if it can create a suid directory, if not the tests are skipped.
Perl builds without errors in a nosuid /tmp with this patch.  (cae9400)

=item C<I18N::LangTags>

Upgraded from version 0.35 to 0.35_01.

=item C<IPC::Cmd>

Upgraded from version 0.58 to 0.60.

=item C<IPC::SysV>

Upgraded from version 2.01 to 2.03.

=item C<Locale::Maketext>

Upgraded from version 1.14 to 1.15.

Locale::Maketext guts have been merged back into the main module (87d86da)
and adds external cache support (ace47d6)

=item C<Module::Build>

Upgraded from version 0.3603 to 0.3607.

=item C<Module::CoreList>

Upgraded from version 2.34 to 2.36.

=item C<Module::Load>

Upgraded from version 0.16 to 0.18.

=item C<Term::ANSIColor>

Upgraded from version 2.02 to 3.00.

=item C<Test::Harness>

Upgraded from version 3.17 to 3.21.

The core update from Test-Harness 3.17 to 3.21 fixed some things, but
also L<introduced a known problem|/"Known Problems"> with argument
passing to non-Perl tests.

=item C<Time::HiRes>

Upgraded from version 1.9719 to 1.9721.

=item C<Time::Piece>

Upgraded from version 1.15_01 to 1.20_01.

=item C<Unicode::Collate>

Upgraded from version 0.52_01 to 0.53.

Includes Unicode Collation Algorithm 18 (74b94a7)

=item C<Unicode::Normalize>

Upgraded from version 1.03 to 1.06.

=back

=head1 Documentation

=head2 New Documentation

=head3 L<perl5121delta>

The Perl 5.12.1 perldelta file was added from the Perl maintenance branch

=head2 Changes to Existing Documentation

=head3 General changes

=over

=item *

Octal character escapes in documentation now prefer a three-digit octal
escape or the new C<\o{...}> escape as they have more consistent behavior
in different contexts than other forms. (ce7b6f0) (d8b950d) (e1f120a)

=item *

Documentation now standardizes on the term 'capture group' over 'buffer'
in regular expression documentation (c27a5cf)

=back

=head3 L<perlfunc>

=over

=item *

Added cautionary note about "no VERSION" (e0de7c2)

=item *

Added additional notes regarding srand when forking (d460397)

=back

=head3 L<perlop>

=over 4

=item *

Improved documentation of unusual character escapes (4068718, 9644846)

=item *

Clarified how hexadecimal escapes are interpreted, with particular
attention to the treatment of invalid characters (9644846)

=back

=head3 L<perlrun>

=over

=item *

Clarified the behavior of the C<-0NNN> switch for C<-0400> or higher (7ba31cb)

=back

=head3 L<perlpolicy>

=over

=item *

Added the policy on compatibility and deprecation along with definitions of
terms like "deprecation" (70e4a83)

=back

=head3 L<perlre>

=over

=item *

Added examples of the perils of not using \g{} when there are more
than nine back-references (9d86067)

=back

=head3 L<perltie>

=over

=item *

Updated some examples for modern Perl style (67d00dd)

=back

=head1 Utility Changes

=head3 L<perldb>

=over

=item *

The remote terminal works after forking and spawns new sessions - one
for each forked process (11653f7)

=item *

Uses the less pager path from Config instead of searching for it (bf320d6)

=back

=head1 Configuration and Compilation

=over 4

=item *

Adjusted 'make test.valgrind' to account for cpan/dist/ext separation
(e07ce2e)

=back

=head1 Testing

=over 4

=item *

F<t/harness> clears PERL5LIB, PERLLIB, PERL5OPT as t/TEST does (a2d3de1)

=item *

Many common testing routines were refactored into t/lib/common.pl

=item *

Several test files have been modernized to use Test::More

=back

=head1 Platform Support

=head2 Discontinued Platforms

=over 4

=item MacOS Classic

Support for MacOS Classic within ExtUtils::MakeMaker was removed from Perl in
December 2004.  Vestigial MacOS Classic specific code has now been removed
from other core modules as well (8f8c2a4..c457df0)

=back

=head2 Platform-Specific Notes

=over 4

=item Win32

t/io/openpid.t now uses the alarm() watchdog strategy for more
robustness (5732108)

=back

=head1 Internal Changes

=over 4

=item *

Under some circumstances, the C<CvGV()> field of a CV is now reference
counted. To ensure consistent behaviour, direct assignment to it, for
example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
C<CvGV_set(cv,gv)> has been introduced to perform this operation safely.
Note that modification of this field is not part of of the public API,
regardless of this new macro. This change caused some
L<issues|/"Known Problems"> in modules that used the private C<GvGV()>
field.

=item *

It is now possible for XS code to hook into Perl's lexical scope
mechanism at compile time, using the new C<Perl_blockhook_register>
function. See L<perlguts/"Compile-time scope hooks">.

=item *

Added C<Perl_croak_no_modify()> to implement
C<Perl_croak("%s", PL_no_modify)> (6ad8f25)

=item *

Added prototypes for C<tie()> and C<untie()> to allow overloading (RT#75902)
(1db4d19)

=item *

Adds C<my_[l]stat_flags()> to replace C<my_[l]stat()>.  C<my_stat()> and
C<my_lstat()> call get magic on the stack arg, so create C<_flags()>
variants that allow us to control this. (0d7d409)

=back

=head1 Selected Bug Fixes

=over 4

=item *

Some work has been done on the internal pointers that link between symbol
tables (stashes), typeglobs and subroutines. This has the effect that
various edge cases related to deleting stashes or stash entries (e.g.
<%FOO:: = ()>), and complex typeglob or code reference aliasing, will no
longer crash the interpreter.

=item *

Fixed readline() when interrupted by signals so it no longer returns
the "same thing" as before or random memory

=item *

Fixed a regression of kill() when a match variable is used for the
process ID to kill  (RT#75812) (8af710e)

=item *

Fixed several subtle bugs in sort() when @_ is accessed within a subroutine
used for sorting (RT#72334) (8f443ca)

=item *

Catch yyparse() exceptions in C<< (?{...}) >> (RT#2353) (634d691)

=item *

Avoid UTF-8 cache panics with offsets beyond a string (RT #75898) (3e2d381)

=item *

Fixed POSIX::strftime memory leak (RT#73520) (c4bc4aa)

=item *

Doesn't set strict with C<no VERSION> if C<VERSION> is greater than 5.12
(da8fb5d)

=item *

Avoids multiple FETCH/stringify on filetest ops (40c852d)

=item *

Fixed issue with string C<eval> not detecting taint of overloaded/tied
arguments (RT #75716) (895b760)

=item *

Fix potential crashes of string C<eval> when evaluating a object with
overloaded stringification by creating a stringified copy when necessary
(3e5c018)

=item *

Fixed bug where overloaded stringification could remove tainting
(RT #75716) (a02ec77)

=item *

Plugs more memory leaks in vms.c. (9e2bec0)

=item *

Fix pthread include error for Time::Piece (e9f284c)

=back

=head1 Known Problems

=over 4

=item *

Bug fixes involving CvGV reference counting break Sub::Name.  A
patch has been sent upstream to the maintainer

=item *

readline() returns an empty string instead of undef when it is
interrupted by a signal

=item *

Test-Harness was updated from 3.17 to 3.21 for this release. A rewrite
in how it handles non-Perl tests (in 3.17_01) broke argument passing to
non-Perl tests with L<prove> (RT #59186), and required that non-Perl
tests be run as C<prove ./test.sh> instead of C<prove test.sh> These
issues are being solved upstream, but didn't make it into this release.
They're expected to be fixed in time for perl v5.13.4.  (RT #59457)

=item *

C<version> now prevents object methods from being called as class methods
(d808b68)

=back

=head1 Errata

=over 4

=item *

Retroactively added the Acknowledgements list to L<perl5132delta>,
which was excluded in the original release (d1e2db0)

=back

=head1 Acknowledgements

Perl 5.13.3 represents approximately one month of development since Perl
5.13.2, and contains 12,184 lines of changes across 575 files from 104
authors and committers.

Thank you to the following for contributing to this release:

Abhijit Menon-Sen, Abigail, Alex Davies, Alex Vandiver, Alexandr
Ciornii, Andreas J. Koenig, Andrew Rodland, Andy Dougherty, Aristotle
Pagaltzis, Arkturuz, Ben Morrow, Bo Borgerson, Bo Lindbergh, Brad
Gilbert, Bram, Brian Phillips, Chas. Owens, Chip Salzenberg, Chris
Williams, Craig A. Berry, Curtis Jewell, Dan Dascalescu, Daniel
Frederick Crisman, Dave Rolsky, David Caldwell, David E. Wheeler, David
Golden, David Leadbeater, David Mitchell, Dennis Kaarsemaker, Eric
Brine, Father Chrysostomos, Florian Ragwitz, Frank Wiegand, Gene
Sullivan, George Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham
Barr, H.Merijn Brand, Harmen, Hugo van der Sanden, James E Keenan, James
Mastros, Jan Dubois, Jerry D. Hedden, Jesse Vincent, Jim Cromie, John
Peacock, Jos Boumans, Josh ben Jore, Karl Williamson, Kevin Ryde, Leon
Brocard, Lubomir Rintel, Maik Hentsche, Marcus Holland-Moritz, Matt
Johnson, Matt S Trout, Max Maischein, Michael Breen, Michael G Schwern,
Moritz Lenz, Nga Tang Chan, Nicholas Clark, Nick Cleaton, Nick Johnston,
Niko Tyni, Offer Kaye, Paul Marquess, Philip Hazel, Philippe Bruhat,
Rafael Garcia-Suarez, Rainer Tammer, Reini Urban, Ricardo Signes,
Richard Soderberg, Robin Barker, Ruslan Zakirov, Salvador Fandino,
Salvador Ortiz Garcia, Shlomi Fish, Sinan Unur, Sisyphus, Slaven Rezic,
Steffen Mueller, Stepan Kasal, Steve Hay, Steve Peters, Sullivan Beck,
Tim Bunce, Todd Rinaldo, Tom Christiansen, Tom Hukins, Tony Cook,
Vincent Pit, Yuval Kogman, Yves Orton, Zefram, brian d foy, chromatic,
kmx, Ævar Arnfjörð Bjarmason

=head1 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 http://rt.perl.org/perlbug/ .  There may also be
information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the B<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 C<perl -V>, will be sent off to perlbug@perl.org 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 perl5-security-report@perl.org. This points to a closed subscription
unarchived mailing list, which includes all the core committers, who 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.

=head1 SEE ALSO

The F<Changes> file for an explanation of how to view exhaustive details
on what changed.

The F<INSTALL> file for how to build Perl.

The F<README> file for general stuff.

The F<Artistic> and F<Copying> files for copyright information.

=cut