3 perldelta - what is new for perl v5.11.2
7 This document describes differences between the 5.11.1 release and
10 =head1 Core Enhancements
14 It is now possible to overload the C<qr//> operator, that is, conversion
15 to regexp, like it was already possible to overload conversion to
16 boolean, string or number of objects. It is invoked when an object
17 appears on the right hand side of the C<=~> operator, or when it is
18 interpolated into a regexp. See L<overload>.
20 =head2 Pluggable keywords
22 Extension modules can now cleanly hook into the Perl parser to define new
23 kinds of keyword-headed expression and compound statement. The syntax
24 following the keyword is defined entirely by the extension. This allow
25 a completely non-Perl sublanguage to be parsed inline, with the right
26 ops cleanly generated. This feature is currently considered experimental.
28 See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core source
29 distribution also includes a new module L<XS::APItest::KeywordRPN>, which
30 implements reverse Polish notation arithmetic via pluggable keywords.
31 This module is mainly used for test purposes, and is not normally
32 installed, but also serves as an example of how to use the new mechanism.
36 We have added a public API for the lowest layers of lexing. This is meant
37 to provide a solid foundation for the parsing that Devel::Declare and
38 similar modules do, and it complements the pluggable keyword mechanism.
39 The API consists of some existing variables combined with some new functions,
40 all marked as experimental (which making them public certainly is).
42 =head2 APIs for more internals
44 The lowest layers of the lexer and parts of the pad system now have C
45 APIs available to XS extensions. These are necessary to support proper
46 use of pluggable keywords, but have other uses too. The new APIs are
47 experimental, and only cover a small proportion of what would be necessary
48 to take full advantage of the core's facilities in these areas. It is
49 intended that the Perl 5.13 development cycle will see the addition of
50 a full range of clean, supported interfaces.
52 =head2 Overridable function lookup
54 Where an extension module hooks the creation of rv2cv ops to modify
55 the subroutine lookup process, this now works correctly for bareword
56 subroutine calls. This means that prototypes on subroutines referenced
57 this way will be processed correctly. (Previously bareword subroutine
58 names were initially looked up, for parsing purposes, by an unhookable
59 mechanism, so extensions could only properly influence subroutine names
60 that appeared with an C<&> sigil.)
62 =head1 Modules and Pragmata
64 =head2 New Modules and Pragmata
70 Preserves legacy behaviors or enable new non-default behaviors.
71 Currently the only behaviour concerns semantics for the 128 characters
72 on ASCII systems that have the 8th bit set.
76 =head2 Pragmata Changes
82 Supports %.0f formatting internally.
86 Allow overloading of 'qr'.
90 =head2 Updated Modules
96 Optimize reversing an array in-place, avoid using defined %hash in core code and tests.
100 Teach B::Deparse about in-place reverse.
104 Refine Carp caller() fix and add tests.
106 =item C<Compress::Zlib>
118 =item C<ExtUtils::CBuilder>
124 Add EXISTS and DELETE methods to Env.pm.
130 =item C<I8N::Langinfo>
132 Correctly document export of I18N::Langinfo.
134 =item C<I8N::LangTags>
136 In I18N::LangTags::Detect, avoid using defined @array and defined %hash.
138 =item C<IO::Compress>
150 =item C<Locale::Maketext>
152 In Locale::Maketext, avoid using defined @array and defined %hash.
153 Convert the odd Locale::Maketext test out from Test to Test::More.
155 =item C<Module::Build>
159 =item C<Module::CoreList>
161 Implemented is_deprecated().
167 =item C<Scalar::Util>
177 =head1 Utility Changes
183 Fixed bugs with the match() operator in list context, remove mention
188 =head1 Performance Enhancements
194 Reversing an array to itself (as in C<@a = reverse @a>) in void context now
195 happens in-place and is several orders of magnitude faster than it used to be.
196 It will also preserve non-existent elements whenever possible, i.e. for non
197 magical arrays or tied arrays with C<EXISTS> and C<DELETE> methods.
201 =head1 New or Changed Diagnostics
203 Several new diagnostics, see L<perldiag> for details.
207 =item C<Bad plugin affecting keyword '%s'>
209 =item C<gmtime(%.0f) too large>
211 =item C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
213 =item C<Lexing code internal error (%s)>
215 =item C<localtime(%.0f) too large>
217 =item C<Overloaded dereference did not return a reference>
219 =item C<Overloaded qr did not return a REGEXP>
221 =item C<Perl_pmflag() is deprecated, and will be removed from the XS API>
225 One diagnostic has been removed:
229 =item C<Runaway format>
233 =head1 Changed Internals
239 C<Perl_pmflag> has been removed from the public API. Calling it now generates
240 a deprecation warning, and it will be removed in a future release. Although
241 listed as part of the API, it was never documented, and only ever used in
242 F<toke.c>, and prior to 5.10, F<regcomp.c>. In core, it has been replaced by a
251 =item F<t/op/while_readdir.t>
253 Test that a bare readdir in while loop sets $_.
257 =head1 Known Problems
261 =item Known test failures on VMS
263 Perl 5.11.2 fails a small set of core and CPAN tests as of this release.
264 With luck, that'll be sorted out for 5.11.3.
270 The following items are now deprecated.
272 =head2 Use of C<:=> to mean an empty attribute list is now deprecated.
274 An accident of Perl's parser meant that these constructions were all equivalent:
280 with the C<:> being treated as the start of an attribute list, which ends
281 before the C<=>. As whitespace is not significant here, all are parsed as an
282 empty attribute list, hence all the above are equivalent to, and better written
287 because no attribute processing is done for an empty list.
289 As is, this meant that C<:=> cannot be used as a new token, without silently
290 changing the meaning of existing code. Hence that particular form is now
291 deprecated, and will become a syntax error. If it is absolutely necessary to
292 have empty attribute lists (for example, because of a code generator) then
293 avoid the warning by adding a space before the C<=>.
295 =head1 Acknowledgements
297 Perl 5.11.2 represents approximately 3 weeks development since Perl 5.11.1
298 contains 29,992 lines of changes across 458 files from 38 authors and committers:
300 Abhijit Menon-Sen, Abigail, Ben Morrow, Bo Borgerson, Brad Gilbert, Bram,
301 Chris Williams, Craig A. Berry, Daniel Frederick Crisman, Dave Rolsky,
302 David E. Wheeler, David Golden, Eric Brine, Father Chrysostomos,
303 Frank Wiegand, Gerard Goossen, Gisle Aas, Graham Barr, Harmen, H.Merijn Brand,
304 Jan Dubois, Jerry D. Hedden, Jesse Vincent, Karl Williamson, Kevin Ryde,
305 Leon Brocard, Nicholas Clark, Paul Marquess, Philippe Bruhat,
306 Rafael Garcia-Suarez, Sisyphus, Steffen Mueller, Steve Hay, Steve Peters,
307 Vincent Pit, Yuval Kogman, Yves Orton, and Zefram.
309 Many of the changes included in this version originated in the CPAN
310 modules included in Perl's core. We're grateful to the entire CPAN
311 community for helping Perl to flourish.
313 =head1 Reporting Bugs
315 If you find what you think is a bug, you might check the articles
316 recently posted to the comp.lang.perl.misc newsgroup and the perl
317 bug database at http://rt.perl.org/perlbug/ . There may also be
318 information at http://www.perl.org/ , the Perl Home Page.
320 If you believe you have an unreported bug, please run the B<perlbug>
321 program included with your release. Be sure to trim your bug down
322 to a tiny but sufficient test case. Your bug report, along with the
323 output of C<perl -V>, will be sent off to perlbug@perl.org to be
324 analysed by the Perl porting team.
326 If the bug you are reporting has security implications, which make it
327 inappropriate to send to a publicly archived mailing list, then please send
328 it to perl5-security-report@perl.org. This points to a closed subscription
329 unarchived mailing list, which includes all the core committers, who be able
330 to help assess the impact of issues, figure out a resolution, and help
331 co-ordinate the release of patches to mitigate or fix the problem across all
332 platforms on which Perl is supported. Please only use this address for
333 security issues in the Perl core, not for modules independently
338 The F<Changes> file for an explanation of how to view exhaustive details
341 The F<INSTALL> file for how to build Perl.
343 The F<README> file for general stuff.
345 The F<Artistic> and F<Copying> files for copyright information.