5 perldelta - what is new for perl v5.13.2
9 This document describes differences between the 5.13.2 release and
12 If you are upgrading from an earlier release such as 5.10, first read
13 L<perl5120delta>, which describes differences between 5.10 and
18 XXX Any important notices here
20 =head1 Incompatible Changes
22 =head2 localised tied scalars are tied again.
24 The change in behaviour in 5.13.1 of localising tied scalar values has
25 been reverted to the existing 5.12.0 and earlier behaviour (the change for
26 arrays and hashes remains).
28 =head1 Core Enhancements
30 XXX New core language features go here. Summarise user-visible core language
31 enhancements. Particularly prominent performance optimisations could go
32 here, but most should go in the L</Performance Enhancements> section.
34 =head2 Non-destructive substitution
36 The substitution operator now supports a C</r> option that
37 copies the input variable, carries out the substitution on
38 the copy and returns the result. The original remains unmodified.
41 my $new = $old =~ s/cat/dog/r;
42 # $old is 'cat' and $new is 'dog'
44 This is particularly useful with C<map>. See L<perlop> for more examples
47 =head2 package block syntax
49 A package declaration can now contain a code block, in which case the
50 declaration is in scope only inside that block. So C<package Foo { ... }>
51 is precisely equivalent to C<{ package Foo; ... }>. It also works with
52 a version number in the declaration, as in C<package Foo 1.2 { ... }>.
53 See L<perlfunc> (434da3..36f77d, 702646).
57 XXX List any platforms that this version of perl compiles on, that previous
58 versions did not. These will either be enabled by new files in the F<hints/>
59 directories, or new subdirectories and F<README> files at the top level of the
62 =head1 Modules and Pragmata
64 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
65 go here. If Module::CoreList is updated, generate an initial draft of the
66 following sections using F<Porting/corelist-perldelta.pl>, which prints stub
67 entries to STDOUT. Results can be pasted in place of the '=head2' entries
68 below. A paragraph summary for important changes should then be added by hand.
69 In an ideal world, dual-life modules would have a F<Changes> file that could be
72 =head2 New Modules and Pragmata
74 =head2 Pragmata Changes
76 =head2 Updated Modules
78 =head2 Removed Modules and Pragmata
80 =head1 Utility Changes
82 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
83 here. Most of these are built within the directories F<utils> and F<x2p>.
93 =head1 New Documentation
95 XXX Changes which create B<new> files in F<pod/> go here.
105 =head1 Changes to Existing Documentation
107 XXX Changes which significantly change existing files in F<pod/> go here.
108 Any changes to F<pod/perldiag.pod> should go in L</New or Changed Diagnostics>.
110 =head2 Replace wrong tr/// table in perlebcdic.pod
112 perlebcdic.pod contains a helpful table to use in tr/// to convert
113 between EBCDIC and Latin1/ASCII. Unfortunately, the table was the
114 inverse of the one it describes, though the code that used the table
115 worked correctly for the specific example given.
117 The table has been changed to its inverse, and the sample code changed
118 to correspond, as this is easier for the person trying to follow the
119 instructions since deriving the old table is somewhat more complicated.
121 The table has also been changed to hex from octal, as that is more the norm
122 these days, and the recipes in the pod altered to print out leading
123 zeros to make all the values the same length, as the table that they can
126 =head2 Document tricks for user-defined casing
128 perlunicode.pod now contains an explanation of how to override, mangle
129 and otherwise tweak the way perl handles upper, lower and other case
130 conversions on unicode data, and how to provide scoped changes to alter
131 one's own code's behaviour without stomping on anybody else (71648f).
133 =head1 Performance Enhancements
135 Only allocate entries for @_ on demand - this not only saves memory per
136 subroutine defined but should hopefully improve COW behaviour (77bac2).
138 Multiple small improvements to threads:
144 Change the internal structured of thread->params from an SV (RV) to an AV
145 - so we now pass around and store the array directly, rather than creating,
146 holding and dereferencing a reference to it (78b7eff).
150 Change S_ithread_create() params from a single AV* to a pair of SV** pointers.
151 This saves creating, duplicating and freeing and AV, which is only ever used for
152 an internal calling convention (4cf5ea).
156 Remove redundant hv_exists() calls from ithread_create()'s spec parser (b1faab).
160 Skip unnecessary newAV() in ithread_create() (39f3f7).
164 Avoid duping pads created for recursion since there's no point pre-allocating
165 the same memory in the new thread (6de654).
169 Eliminated xhv_fill from struct xpvhv: This saves 1 IV per hash and on some
170 systems will cause struct xpvhv to become cache aligned. To avoid this
171 memory saving causing a slowdown elsewhere, boolean use of HvFILL now
172 calls HvTOTALKEYS instead (which is equivalent) - so while the fill data when
173 actually required is now calculated on demand, the cases when this needs to
174 be done should be few and far between (f4431c .. fcd245).
176 =head1 Installation and Configuration Improvements
178 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
181 =head2 Configuration improvements
185 =head2 Compilation improvements
187 Fix CCINCDIR and CCLIBDIR for mingw64 cross compiler to correctly be under
188 $(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
190 This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
191 'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
192 set correctly (23ae7f).
194 =head2 Platform Specific Changes
198 =item XXX-some-platform
204 =head1 Selected Bug Fixes
206 Timely cleanup of SVs that are cloned into a new thread but then discovered
207 to be orphaned (i.e. their owners are -not- cloned) (e42956)
209 Don't accidentally clone lexicals in scope within active stack frames in
210 the parent when creating a child thread (RT #73086) (05d04d).
212 Avoid loading feature.pm when 'no 5.13.2;' or similar is encountered (faee19).
214 Trap invalid use of SvIVX on SVt_REGEXP when assertions are on (e77da3)
216 Don't stamp on $DB::single, $DB::trace and $DB::signal if they already have
217 values when $^P is assigned to (RT #72422) (4c0f30).
223 Overloading now works properly in conjunction with tied variables. What
224 formerly happened was that most ops checked their arguments for overloading
225 I<before> checking for magic, so for example an overloaded object returned
226 by a tied array access would usually be treated as not overloaded
227 (RT #57012) (6f1401, ed3b9b, 6a5f8c .. 24328f).
231 =head1 New or Changed Diagnostics
233 XXX New or changed warnings emitted by the core's C<C> code go here.
243 =head1 Changed Internals
245 XXX Changes which affect the interface available to C<XS> code go here.
251 The C<find_rundefsvoffset> function has been deprecated. It appeared that
252 its design was insufficient to reliably get the lexical C<$_> at run-time.
254 Use the new C<find_rundefsv> function or the C<UNDERBAR> macro instead.
255 They directly return the right SV representing C<$_>, whether it's lexical
260 The following new functions or macros have been added to the public API:
261 C<SvNV_nomg>, C<sv_2nv_flags>, C<find_rundefsv>.
265 The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
266 noop but should still be used to ensure past and future compatibility.
272 XXX Changes which create B<new> files in F<t/> go here. Changes to
273 existing files in F<t/> aren't worth summarising, although the bugs that
274 they represent may be.
284 =head1 Known Problems
286 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
287 tests that had to be C<TODO>ed for the release would be noted here, unless
288 they were specific to a particular platform (see below).
290 This is a list of some significant unfixed bugs, which are regressions
291 from either 5.XXX.XXX or 5.XXX.XXX.
303 XXX Add any new known deprecations here.
305 The following items are now deprecated.
311 Omitting a space between a regex pattern or pattern modifiers and the following
312 word is deprecated. For example, C<< m/foo/sand $bar >> will still be parsed
313 as C<< m/foo/s and $bar >> but will issue a warning.
317 =head1 Platform Specific Notes
319 XXX Any changes specific to a particular platform. VMS and Win32 are the usual
320 stars here. It's probably best to group changes under the same section layout
321 as the main perldelta
325 XXX If any significant core contributor has died, we've added a short obituary
328 =head1 Acknowledgements
330 XXX The list of people to thank goes here.
332 Your humble release manager would like to specifically call out
333 Karl Williamson for making the tests a better place to be, and Shlomi
334 Fish for a passel of tiny incremental docfixes of the sort that don't get
337 =head1 Reporting Bugs
339 If you find what you think is a bug, you might check the articles
340 recently posted to the comp.lang.perl.misc newsgroup and the perl
341 bug database at http://rt.perl.org/perlbug/ . There may also be
342 information at http://www.perl.org/ , the Perl Home Page.
344 If you believe you have an unreported bug, please run the B<perlbug>
345 program included with your release. Be sure to trim your bug down
346 to a tiny but sufficient test case. Your bug report, along with the
347 output of C<perl -V>, will be sent off to perlbug@perl.org to be
348 analysed by the Perl porting team.
350 If the bug you are reporting has security implications, which make it
351 inappropriate to send to a publicly archived mailing list, then please send
352 it to perl5-security-report@perl.org. This points to a closed subscription
353 unarchived mailing list, which includes all the core committers, who be able
354 to help assess the impact of issues, figure out a resolution, and help
355 co-ordinate the release of patches to mitigate or fix the problem across all
356 platforms on which Perl is supported. Please only use this address for
357 security issues in the Perl core, not for modules independently
362 The F<Changes> file for an explanation of how to view exhaustive details
365 The F<INSTALL> file for how to build Perl.
367 The F<README> file for general stuff.
369 The F<Artistic> and F<Copying> files for copyright information.