doc f7abe7

[p5sagit/p5-mst-13.2.git] / pod / perl5132delta.pod

=encoding utf8

=head1 NAME

perldelta - what is new for perl v5.13.2

=head1 DESCRIPTION

This document describes differences between the 5.13.2 release and
the 5.13.1 release.

If you are upgrading from an earlier release such as 5.10, first read
L<perl5120delta>, which describes differences between 5.10 and
5.12.

=head1 Notice

XXX Any important notices here

=head1 Incompatible Changes

=head2 localised tied scalars are tied again.

The change in behaviour in 5.13.1 of localising tied scalar values has
been reverted to the existing 5.12.0 and earlier behaviour (the change for
arrays and hashes remains).

=head2 Naming fixes in Policy_sh.SH may invalidate Policy.sh

Several long-standing typos and naming confusions in Policy_sh.SH have
been fixed, standardizing on the variable names used in config.sh.

This will change the behavior of Policy.sh if you happen to have been
accidentally relying on the Policy.sh incorrect behavior. We'd appreciate
feedback from anyone using Policy.sh to be sure nothing is broken by
this change (c1bd23).

=head2 Stashes are now always defined

%stash:: is now autovivified so 'defined %Foo::' always returns true
- although calling defined on a stash is now deprecated.

=head1 Core Enhancements

=head2 Non-destructive substitution

The substitution operator now supports a C</r> option that
copies the input variable, carries out the substitution on
the copy and returns the result.  The original remains unmodified.

  my $old = 'cat';
  my $new = $old =~ s/cat/dog/r;
  # $old is 'cat' and $new is 'dog'

This is particularly useful with C<map>.  See L<perlop> for more examples
(4f4d75, 000c65).

=head2 package block syntax

A package declaration can now contain a code block, in which case the
declaration is in scope only inside that block.  So C<package Foo { ... }>
is precisely equivalent to C<{ package Foo; ... }>.  It also works with
a version number in the declaration, as in C<package Foo 1.2 { ... }>.
See L<perlfunc> (434da3..36f77d, 702646).

=head2 CLONE_PARAMS structure added to ease correct thread creation

Modules that create threads should now create C<CLONE_PARAMS> structures
by calling the new function C<Perl_clone_params_new()>, and free them with
C<Perl_clone_params_del()>. This will ensure compatibility with any future
changes to the internals of the C<CLONE_PARAMS> structure layout, and that
it is correctly allocated and initialised.

=head2 perl -h no longer recommends -w

perl -h used to mark the -w option as recommended; since this option is
far less useful than it used to be due to lexical 'use warnings' and since
perl -h is primary a list and brief explanation of the command line switches,
the recommendation has now been removed (60eaec).

=head1 New Platforms

XXX List any platforms that this version of perl compiles on, that previous
versions did not. These will either be enabled by new files in the F<hints/>
directories, or new subdirectories and F<README> files at the top level of the
source tree.

=head1 Modules and Pragmata

XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
go here.  If Module::CoreList is updated, generate an initial draft of the
following sections using F<Porting/corelist-perldelta.pl>, which prints stub
entries to STDOUT.  Results can be pasted in place of the '=head2' entries
below.  A paragraph summary for important changes should then be added by hand.
In an ideal world, dual-life modules would have a F<Changes> file that could be
cribbed.

=head2 New Modules and Pragmata

=head2 Pragmata Changes

=head2 Updated Modules

=head2 Locale-Codes 3.13

Locale::Country, Locale::Language and Locale::Currency were updated from
3.12 to 3.13 of the Locale-Codes distribution to include locale code changes
(e1137b).

=head2 Thread-Semaphore 2.11

Added new methods ->down_nb() and ->down_force() at the suggestion of Rick
Garlick.

Refactored methods to skip argument validation when no argument is supplied.

(04febe, f06daa)

=head2 CPAN.pm 1.94_57
   
            * release 1.94_57
   
            * bugfix: treat modules correctly that are deprecated in perl 5.12.
   
            * bugfix: RT #57482 and #57788 revealed that configure_requires
            implicitly assumed build_requires instead of normal requires. (Reported
            by Andrew Whatson and Father Chrysostomos respectively)
   
            * testfix: solaris should run the tests without expect because (some?)
            solaris have a broken expect
   
            * testfix: run tests with cache_metadata off to prevent spill over
            effects from previous test runs

(742adb)

=head2 Hash::Util warning fix

Hash::Util now enables "no warnings 'uninitialized'" to suppress spurious
warnings from undefined hash values (RT #74280).

=head2 Removed Modules and Pragmata

=head1 Utility Changes

XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
here. Most of these are built within the directories F<utils> and F<x2p>.

=over 4

=item F<XXX>

XXX

=back

=head1 New Documentation

XXX Changes which create B<new> files in F<pod/> go here.

=over 4

=item L<XXX>

XXX

=back

=head1 Changes to Existing Documentation

XXX Changes which significantly change existing files in F<pod/> go here.
Any changes to F<pod/perldiag.pod> should go in L</New or Changed Diagnostics>.

=head2 Replace wrong tr/// table in perlebcdic.pod

perlebcdic.pod contains a helpful table to use in tr/// to convert
between EBCDIC and Latin1/ASCII.  Unfortunately, the table was the
inverse of the one it describes, though the code that used the table
worked correctly for the specific example given.

The table has been changed to its inverse, and the sample code changed
to correspond, as this is easier for the person trying to follow the
instructions since deriving the old table is somewhat more complicated.

The table has also been changed to hex from octal, as that is more the norm
these days, and the recipes in the pod altered to print out leading
zeros to make all the values the same length, as the table that they can
generate has them (5f26d5).

=head2 Document tricks for user-defined casing

perlunicode.pod now contains an explanation of how to override, mangle
and otherwise tweak the way perl handles upper, lower and other case
conversions on unicode data, and how to provide scoped changes to alter
one's own code's behaviour without stomping on anybody else (71648f).

=head2 Document $# and $* as removed and clarify $#array usage

$# and $* were both disabled as of perl5 version 10; this release adds
documentation to that effect, a description of the results of continuing
to try and use them, and a note explaining that $# can also function as a
sigil in the $#array form (7f315d2).

=head2 INSTALL explicitly states the requirement for C89

This was already true but it's now Officially Stated For The Record (51eec7).

=head2 No longer advertise Math::TrulyRandom

This module hasn't been updated since 1996 so we can't recommend it any more
(83918a).

=head2 perlfaq synchronised to upstream

The FAQ has been updated to commit
37550b8f812e591bcd0dd869d61677dac5bda92c from the perlfaq repository
at git@github.com:briandfoy/perlfaq.git

=head1 Performance Enhancements

Only allocate entries for @_ on demand - this not only saves memory per
subroutine defined but should hopefully improve COW behaviour (77bac2).

=head2 Multiple small improvements to threads

The internal structures of threading now make fewer API calls and fewer
allocations, resulting in noticeably smaller object code. Additionally,
many thread context checks have been deferred so that they're only done
when required (although this is only possible for non-debugging builds).

=head2 Size optimisations to SV and HV structures

xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and
on some systems will cause struct xpvhv to become cache aligned. To avoid
this memory saving causing a slowdown elsewhere, boolean use of HvFILL
now calls HvTOTALKEYS instead (which is equivalent) - so while the fill
data when actually required is now calculated on demand, the cases when
this needs to be done should be few and far between (f4431c .. fcd245).

The order of structure elements in SV bodies has changed. Effectively,
the NV slot has swapped location with STASH and MAGIC. As all access to
SV members is via macros, this should be completely transparent. This
change allows the space saving for PVHVs documented above, and may reduce
the memory allocation needed for PVIVs on some architectures.

=head2 Optimisation of regexp engine string comparison work

The foldEQ_utf8 API function for case-insensitive comparison of strings (which
is used heavily by the regexp engine) was substantially refactored and
optimised - and its documentation much improved as a free bonus gift
(8b3587, e6226b).

=head2 Memory consumption improvements to Exporter

The @EXPORT_FAIL AV is no longer created unless required, hence neither is
the typeglob backing it - this saves about 200 bytes per Exporter using
package that doesn't use this functionality.

=head1 Installation and Configuration Improvements

XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
go here.

=head2 Configuration improvements

XXX

=head2 Compilation improvements

Fix CCINCDIR and CCLIBDIR for mingw64 cross compiler to correctly be under
$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).

This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
set correctly (23ae7f).

=head2 Platform Specific Changes

=over 4

=item XXX-some-platform

XXX

=back

=head1 Selected Bug Fixes

Timely cleanup of SVs that are cloned into a new thread but then discovered
to be orphaned (i.e. their owners are -not- cloned) (e42956)

Don't accidentally clone lexicals in scope within active stack frames in
the parent when creating a child thread (RT #73086) (05d04d).

Avoid loading feature.pm when 'no 5.13.2;' or similar is encountered (faee19).

Trap invalid use of SvIVX on SVt_REGEXP when assertions are on (e77da3)

Don't stamp on $DB::single, $DB::trace and $DB::signal if they already have
values when $^P is assigned to (RT #72422) (4c0f30).

chop now correctly handles perl's extended UTF-8 (RT #73246) (65ab92)

Defer signal handling when shared SV locks are held to avoid deadlocks
(RT #74868) (65c742).

glob() no longer crashes when %File::Glob:: is empty and CORE::GLOBAL::glob
isn't present (4984aa).

perlbug now always permits the sender address to be changed before sending
- if you were having trouble sending bug reports before now, this should
fix it, we hope (e6eb90).

=over 4

=item *

Overloading now works properly in conjunction with tied variables. What
formerly happened was that most ops checked their arguments for overloading
I<before> checking for magic, so for example an overloaded object returned
by a tied array access would usually be treated as not overloaded
(RT #57012) (6f1401, ed3b9b, 6a5f8c .. 24328f).

=back

Independently, a bug was fixed that prevented $tied->() from always calling
FETCH correctly (RT #8438) (7c7501)

=head1 New or Changed Diagnostics

XXX New or changed warnings emitted by the core's C<C> code go here.

=over 4

=item C<XXX>

XXX

=back

=head1 Changed Internals

The implementation of sv_dup_inc() has changed from a macro to a function.

=over 4

=item *

The C<find_rundefsvoffset> function has been deprecated. It appeared that
its design was insufficient to reliably get the lexical C<$_> at run-time.

Use the new C<find_rundefsv> function or the C<UNDERBAR> macro instead.
They directly return the right SV representing C<$_>, whether it's lexical
or dynamic (789bd8 .. 03d5bc).

=item *

The following new functions or macros have been added to the public API:
C<SvNV_nomg>,  C<sv_2nv_flags>, C<find_rundefsv>.

=item *

The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
noop but should still be used to ensure past and future compatibility.

=item *

The ibcmp_* functions have been renamed and are now called foldEQ,
foldEQ_locale and foldEQ_utf8 (e6226b).

=item *

The ibcmp_* functions have been renamed and are now called foldEQ,
foldEQ_locale and foldEQ_utf8 (e6226b).

=back

=head1 New Tests

XXX Changes which create B<new> files in F<t/> go here. Changes to
existing files in F<t/> aren't worth summarising, although the bugs that
they represent may be.

=over 4

=item F<XXX>

XXX

=back

=head1 Known Problems

XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
tests that had to be C<TODO>ed for the release would be noted here, unless
they were specific to a particular platform (see below).

This is a list of some significant unfixed bugs, which are regressions
from either 5.XXX.XXX or 5.XXX.XXX.

=over 4

=item *

XXX

=back

=head1 Deprecations

XXX Add any new known deprecations here.

The following items are now deprecated.

=over 4

=item *

Omitting a space between a regex pattern or pattern modifiers and the following
word is deprecated.  For example, C<< m/foo/sand $bar >> will still be parsed
as C<< m/foo/s and $bar >> but will issue a warning.

=back

=head1 Platform Specific Notes

=head2 Recent OpenBSDs now use perl's malloc

OpenBSD > 3.7 has a new malloc implementation which is mmap based and as such
can release memory back to the OS; however for perl using this malloc causes
a substantial slowdown so we now default to using perl's malloc instead
(RT #75742) (9b58b5).

=head1 Obituary

XXX If any significant core contributor has died, we've added a short obituary
here.

=head1 Acknowledgements

XXX The list of people to thank goes here.

Your humble release manager would like to specifically call out
Karl Williamson for making the tests a better place to be, and Shlomi
Fish for a passel of tiny incremental docfixes of the sort that don't get
made often enough.

=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