3 [ Any text flagged as XXX needs to be processed before release. ]
5 perldelta - what is new for perl v5.11.2
9 This document describes differences between the 5.11.1 release and
14 XXX Unlikely to need this section.
16 =head1 Incompatible Changes
18 =head2 Use of C<:=> to mean an empty attribute list is now deprecated.
20 An accident of Perl's parser means that these constructions are all equivalent:
26 with the C<:> being treated as the start of an attribute list, which ends
27 before the C<=>. As whitespace is not significant here, all are parsed as an
28 empty attribute list, hence all the above are equivalent to, and better written
33 because no attribute processing is done for an empty list.
35 As is, this means that C<:=> cannot be used as a new token, without silently
36 changing the meaning of existing code. Hence that particular form is now
37 deprecated, and will become a syntax error. If it is absolutely necessary to
38 have empty attribute lists (for example, because of a code generator) the
39 avoid the warning by adding a space before the C<=>.
41 =head1 Core Enhancements
43 XXX New core language features go here. Summarise user-visible core language
44 enhancements. Particularly prominent performance optimisations could go
45 here, but most should go in the L</Performance Enhancements> section.
49 It is now possible to overload the C<qr//> operator, that is, conversion
50 to regexp, like it was already possible to overload conversion to
51 boolean, string or number of objects. It is invoked when an object
52 appears on the right hand side of the C<=~> operator, or when it is
53 interpolated into a regexp. See L<overload>.
55 =head2 Pluggable keywords
57 Extension modules can now cleanly hook into the Perl parser to define new
58 kinds of keyword-headed expression and compound statement. The syntax
59 following the keyword is defined entirely by the extension. This allow
60 a completely non-Perl sublanguage to be parsed inline, with the right
61 ops cleanly generated. This feature is currently considered experimental.
63 See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core source
64 distribution also includes a new module L<XS::APItest::KeywordRPN>, which
65 implements reverse Polish notation arithmetic via pluggable keywords.
66 This module is mainly used for test purposes, and is not normally
67 installed, but also serves as an example of how to use the new mechanism.
69 =head2 APIs for more internals
71 The lowest layers of the lexer and parts of the pad system now have C
72 APIs available to XS extensions. These are necessary to support proper
73 use of pluggable keywords, but have other uses too. The new APIs are
74 experimental, and only cover a small proportion of what would be necessary
75 to take full advantage of the core's facilities in these areas. It is
76 intended that the Perl 5.13 development cycle will see the addition of
77 a full range of clean, supported interfaces.
79 =head2 Overridable function lookup
81 Where an extension module hooks the creation of rv2cv ops, to modify
82 the subroutine lookup process, this now works correctly for bareword
83 subroutine calls. This means that prototypes on subroutines referenced
84 this way will be processed correctly. (Previously bareword subroutine
85 names were initially looked up, for parsing purposes, by an unhookable
86 mechanism, so extensions could only properly influence subroutine names
87 that appeared with an C<&> sigil.)
91 XXX List any platforms that this version of perl compiles on, that previous
92 versions did not. These will either be enabled by new files in the F<hints/>
93 directories, or new subdirectories and F<README> files at the top level of the
96 =head1 Modules and Pragmata
98 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
99 go here, in a list ordered by distribution name. Minimally it should be the
100 module version, but it's more useful to the end user to give a paragraph's
101 summary of the module's changes. In an ideal world, dual-life modules would
102 have a F<Changes> file that could be cribbed.
104 =head2 New Modules and Pragmata
114 =head2 Pragmata Changes
124 =head2 Updated Modules
134 =head1 Utility Changes
136 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
137 here. Most of these are built within the directories F<utils> and F<x2p>.
147 =head1 New Documentation
149 XXX Changes which create B<new> files in F<pod/> go here.
159 =head1 Changes to Existing Documentation
161 XXX Changes which significantly change existing files in F<pod/> go here.
162 Any changes to F<pod/perldiag.pod> should go in L</New or Changed Diagnostics>.
165 =head1 Performance Enhancements
171 Reversing an array to itself (as in C<@a = reverse @a>) in void context now
172 happens in-place and is several orders of magnitude faster than it used to be.
173 It will also preserve non-existent elements whenever possible, i.e. for non
174 magical arrays or tied arrays with C<EXISTS> and C<DELETE> methods.
178 =head1 Installation and Configuration Improvements
180 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
183 =head2 Configuration improvements
187 =head2 Compilation improvements
191 =head2 Platform Specific Changes
195 =item XXX-some-platform
201 =head1 Selected Bug Fixes
203 XXX Important bug fixes in the core language are summarised here.
204 Bug fixes in files in F<ext/> and F<lib/> are best summarised in
205 L</Modules and Pragmata>.
215 =head1 New or Changed Diagnostics
217 XXX New or changed warnings emitted by the core's C<C> code go here.
227 =head1 Changed Internals
233 C<Perl_pmflag> has been removed from the public API. Calling it now generates
234 a deprecation warning, and it will be removed in a future release. Although
235 listed as part of the API, it was never documented, and only ever used in
236 F<toke.c>, and prior to 5.10, F<regcomp.c>. In core, it has been replaced by a
243 XXX Changes which create B<new> files in F<t/> go here. Changes to
244 existing files in F<t/> aren't worth summarising, although the bugs that
245 they represent may be.
255 =head1 Known Problems
257 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
258 tests that had to be C<TODO>ed for the release would be noted here, unless
259 they were specific to a particular platform (see below).
261 This is a list of some significant unfixed bugs, which are regressions
262 from either 5.10.1 or 5.11.1.
274 XXX Add any new known deprecations here.
276 The following items are now deprecated.
286 =head1 Platform Specific Notes
288 XXX Any changes specific to a particular platform. VMS and Win32 are the usual
289 stars here. It's probably best to group changes under the same section layout
290 as the main perldelta
294 XXX If any significant core contributor has died, we've added a short obituary
297 =head1 Acknowledgements
299 XXX The list of people to thank goes here.
302 =head1 Reporting Bugs
304 If you find what you think is a bug, you might check the articles
305 recently posted to the comp.lang.perl.misc newsgroup and the perl
306 bug database at http://rt.perl.org/perlbug/ . There may also be
307 information at http://www.perl.org/ , the Perl Home Page.
309 If you believe you have an unreported bug, please run the B<perlbug>
310 program included with your release. Be sure to trim your bug down
311 to a tiny but sufficient test case. Your bug report, along with the
312 output of C<perl -V>, will be sent off to perlbug@perl.org to be
313 analysed by the Perl porting team.
315 If the bug you are reporting has security implications, which make it
316 inappropriate to send to a publicly archived mailing list, then please send
317 it to perl5-security-report@perl.org. This points to a closed subscription
318 unarchived mailing list, which includes all the core committers, who be able
319 to help assess the impact of issues, figure out a resolution, and help
320 co-ordinate the release of patches to mitigate or fix the problem across all
321 platforms on which Perl is supported. Please only use this address for
322 security issues in the Perl core, not for modules independently
327 The F<Changes> file for an explanation of how to view exhaustive details
330 The F<INSTALL> file for how to build Perl.
332 The F<README> file for general stuff.
334 The F<Artistic> and F<Copying> files for copyright information.