[perl5.git] / pod / perl5112delta.pod

=head1 NAME

[ Any text flagged as XXX needs to be processed before release. ]

perldelta - what is new for perl v5.11.2

=head1 DESCRIPTION

This document describes differences between the 5.11.1 release and
the 5.11.2 release.

=head1 Notice

XXX Unlikely to need this section.

=head1 Incompatible Changes

=head2 Use of C<:=> to mean an empty attribute list is now deprecated.

An accident of Perl's parser means that these constructions are all equivalent:

    my $pi := 4;
    my $pi : = 4;
    my $pi :  = 4;

with the C<:> being treated as the start of an attribute list, which ends
before the C<=>. As whitespace is not significant here, all are parsed as an
empty attribute list, hence all the above are equivalent to, and better written
as

    my $pi = 4;

because no attribute processing is done for an empty list.

As is, this means that C<:=> cannot be used as a new token, without silently
changing the meaning of existing code. Hence that particular form is now
deprecated, and will become a syntax error. If it is absolutely necessary to
have empty attribute lists (for example, because of a code generator) the
avoid the warning by adding a space before the C<=>.

=head1 Core Enhancements

XXX New core language features go here. Summarise user-visible core language
enhancements. Particularly prominent performance optimisations could go
here, but most should go in the L</Performance Enhancements> section.

=head2 qr overloading

It is now possible to overload the C<qr//> operator, that is, conversion
to regexp, like it was already possible to overload conversion to
boolean, string or number of objects. It is invoked when an object
appears on the right hand side of the C<=~> operator, or when it is
interpolated into a regexp. See L<overload>.

=head2 Pluggable keywords

Extension modules can now cleanly hook into the Perl parser to define new
kinds of keyword-headed expression and compound statement.  The syntax
following the keyword is defined entirely by the extension.  This allow
a completely non-Perl sublanguage to be parsed inline, with the right
ops cleanly generated.

This feature is currently considered experimental, and using it to do
anything interesting is difficult.  Many necessary supporting facilities,
such as the lexer and the pad system, can only be accessed through
unsupported internal interfaces.  It is intended that the Perl 5.13
development cycle will see the addition of clean, supported interfaces
for many of these functions.  In Perl 5.12 most uses of pluggable keywords
will be via L<Devel::Declare>.

See L<perlapi/PL_keyword_plugin> for the mechanism.  The Perl core source
distribution also includes a new module L<XS::APItest::KeywordRPN>, which
implements reverse Polish notation arithmetic via pluggable keywords.
This module is mainly used for test purposes, and is not normally
installed, but also serves as an example of how to use the new mechanism.

=head2 Overridable function lookup

Where an extension module hooks the creation of rv2cv ops, to modify
the subroutine lookup process, this now works correctly for bareword
subroutine calls.  This means that prototypes on subroutines referenced
this way will be processed correctly.  (Previously bareword subroutine
names were initially looked up, for parsing purposes, by an unhookable
mechanism, so extensions could only properly influence subroutine names
that appeared with an C<&> sigil.)

=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, in a list ordered by distribution name. Minimally it should be the
module version, but it's more useful to the end user to give a paragraph's
summary of the module's changes. In an ideal world, dual-life modules would
have a F<Changes> file that could be cribbed.

=head2 New Modules and Pragmata

=over 4

=item C<XXX>

XXX

=back

=head2 Pragmata Changes

=over 4

=item C<XXX>

XXX

=back

=head2 Updated Modules

=over 4

=item C<XXX>

XXX

=back

=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>.


=head1 Performance Enhancements

XXX Changes which enhance performance without changing behaviour go here. There
may well be none in a stable release.

=over 4

=item *

XXX

=back

=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

XXX

=head2 Platform Specific Changes

=over 4

=item XXX-some-platform

XXX

=back

=head1 Selected Bug Fixes

XXX Important bug fixes in the core language are summarised here.
Bug fixes in files in F<ext/> and F<lib/> are best summarised in
L</Modules and Pragmata>.

=over 4

=item *

XXX

=back

=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

=over 4

=item *

C<Perl_pmflag> has been removed from the public API. Calling it now generates
a deprecation warning, and it will be removed in a future release. Although
listed as part of the API, it was never documented, and only ever used in
F<toke.c>, and prior to 5.10, F<regcomp.c>. In core, it has been replaced by a
static function.

=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 5.10.1 or 5.11.1.

=over 4

=item *

XXX

=back

=head1 Deprecations

XXX Add any new known deprecations here.

The following items are now deprecated.

=over 4

=item *

XXX

=back

=head1 Platform Specific Notes

XXX Any changes specific to a particular platform. VMS and Win32 are the usual
stars here. It's probably best to group changes under the same section layout
as the main perldelta

=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.


=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
Commit	Line	Data
d5114285 NC	1	=head1 NAME
	2
	3	[ Any text flagged as XXX needs to be processed before release. ]
	4
	5	perldelta - what is new for perl v5.11.2
	6
	7	=head1 DESCRIPTION
	8
	9	This document describes differences between the 5.11.1 release and
	10	the 5.11.2 release.
	11
	12	=head1 Notice
	13
	14	XXX Unlikely to need this section.
	15
	16	=head1 Incompatible Changes
	17
d83f38d8	18	=head2 Use of C<:=> to mean an empty attribute list is now deprecated.
d5114285	19
d83f38d8	20	An accident of Perl's parser means that these constructions are all equivalent:
d5114285	21
d83f38d8 NC	22	my $pi := 4;
	23	my $pi : = 4;
	24	my $pi : = 4;
	25
	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
	29	as
	30
	31	my $pi = 4;
	32
	33	because no attribute processing is done for an empty list.
	34
	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<=>.
d5114285 NC	40
	41	=head1 Core Enhancements
	42
	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.
	46
97352077 RGS	47	=head2 qr overloading
	48
	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>.
	54
88e1f1a2 JV	55	=head2 Pluggable keywords
	56
	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.
	62
	63	This feature is currently considered experimental, and using it to do
	64	anything interesting is difficult. Many necessary supporting facilities,
	65	such as the lexer and the pad system, can only be accessed through
	66	unsupported internal interfaces. It is intended that the Perl 5.13
	67	development cycle will see the addition of clean, supported interfaces
	68	for many of these functions. In Perl 5.12 most uses of pluggable keywords
	69	will be via L<Devel::Declare>.
	70
	71	See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core source
	72	distribution also includes a new module L<XS::APItest::KeywordRPN>, which
	73	implements reverse Polish notation arithmetic via pluggable keywords.
	74	This module is mainly used for test purposes, and is not normally
	75	installed, but also serves as an example of how to use the new mechanism.
	76
f7461760 Z	77	=head2 Overridable function lookup
	78
	79	Where an extension module hooks the creation of rv2cv ops, to modify
	80	the subroutine lookup process, this now works correctly for bareword
	81	subroutine calls. This means that prototypes on subroutines referenced
	82	this way will be processed correctly. (Previously bareword subroutine
	83	names were initially looked up, for parsing purposes, by an unhookable
	84	mechanism, so extensions could only properly influence subroutine names
	85	that appeared with an C<&> sigil.)
	86
d5114285 NC	87	=head1 New Platforms
	88
	89	XXX List any platforms that this version of perl compiles on, that previous
	90	versions did not. These will either be enabled by new files in the F<hints/>
	91	directories, or new subdirectories and F<README> files at the top level of the
	92	source tree.
	93
	94	=head1 Modules and Pragmata
	95
	96	XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
	97	go here, in a list ordered by distribution name. Minimally it should be the
	98	module version, but it's more useful to the end user to give a paragraph's
	99	summary of the module's changes. In an ideal world, dual-life modules would
	100	have a F<Changes> file that could be cribbed.
	101
	102	=head2 New Modules and Pragmata
	103
	104	=over 4
	105
	106	=item C<XXX>
	107
	108	XXX
	109
	110	=back
	111
	112	=head2 Pragmata Changes
	113
	114	=over 4
	115
	116	=item C<XXX>
	117
	118	XXX
	119
	120	=back
	121
	122	=head2 Updated Modules
	123
	124	=over 4
	125
	126	=item C<XXX>
	127
	128	XXX
	129
	130	=back
	131
	132	=head1 Utility Changes
	133
	134	XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
	135	here. Most of these are built within the directories F<utils> and F<x2p>.
	136
	137	=over 4
	138
	139	=item F<XXX>
	140
	141	XXX
	142
	143	=back
	144
	145	=head1 New Documentation
	146
	147	XXX Changes which create B<new> files in F<pod/> go here.
	148
	149	=over 4
	150
151	=item L<XXX>
152
153	XXX
154
155	=back
156
157	=head1 Changes to Existing Documentation
158
159	XXX Changes which significantly change existing files in F<pod/> go here.
160	Any changes to F<pod/perldiag.pod> should go in L</New or Changed Diagnostics>.
161
162
163	=head1 Performance Enhancements
164
165	XXX Changes which enhance performance without changing behaviour go here. There
166	may well be none in a stable release.
167
168	=over 4
169
170	=item *
171
172	XXX
173
174	=back
175
176	=head1 Installation and Configuration Improvements
177
178	XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
179	go here.
180
181	=head2 Configuration improvements
182
183	XXX
184
185	=head2 Compilation improvements
186
187	XXX
188
189	=head2 Platform Specific Changes
190
191	=over 4
192
193	=item XXX-some-platform
194
195	XXX
196
197	=back
198
199	=head1 Selected Bug Fixes
200
201	XXX Important bug fixes in the core language are summarised here.
202	Bug fixes in files in F<ext/> and F<lib/> are best summarised in
203	L</Modules and Pragmata>.
204
205	=over 4
206
207	=item *
208
209	XXX
210
211	=back
212
213	=head1 New or Changed Diagnostics
214
215	XXX New or changed warnings emitted by the core's C<C> code go here.
216
217	=over 4
218
219	=item C<XXX>
220
221	XXX
222
223	=back
224
225	=head1 Changed Internals
226
d5114285 NC	227	=over 4
	228
	229	=item *
	230
879d0c72 NC	231	C<Perl_pmflag> has been removed from the public API. Calling it now generates
	232	a deprecation warning, and it will be removed in a future release. Although
	233	listed as part of the API, it was never documented, and only ever used in
	234	F<toke.c>, and prior to 5.10, F<regcomp.c>. In core, it has been replaced by a
	235	static function.
d5114285 NC	236
	237	=back
	238
	239	=head1 New Tests
	240
	241	XXX Changes which create B<new> files in F<t/> go here. Changes to
	242	existing files in F<t/> aren't worth summarising, although the bugs that
	243	they represent may be.
	244
	245	=over 4
	246
	247	=item F<XXX>
	248
	249	XXX
	250
	251	=back
	252
	253	=head1 Known Problems
	254
	255	XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
	256	tests that had to be C<TODO>ed for the release would be noted here, unless
	257	they were specific to a particular platform (see below).
	258
	259	This is a list of some significant unfixed bugs, which are regressions
	260	from either 5.10.1 or 5.11.1.
	261
	262	=over 4
	263
	264	=item *
	265
	266	XXX
	267
	268	=back
	269
	270	=head1 Deprecations
	271
	272	XXX Add any new known deprecations here.
	273
	274	The following items are now deprecated.
	275
	276	=over 4
	277
	278	=item *
	279
	280	XXX
	281
	282	=back
	283
	284	=head1 Platform Specific Notes
	285
	286	XXX Any changes specific to a particular platform. VMS and Win32 are the usual
	287	stars here. It's probably best to group changes under the same section layout
	288	as the main perldelta
	289
	290	=head1 Obituary
	291
	292	XXX If any significant core contributor has died, we've added a short obituary
	293	here.
	294
	295	=head1 Acknowledgements
	296
	297	XXX The list of people to thank goes here.
	298
	299
300	=head1 Reporting Bugs
301
302	If you find what you think is a bug, you might check the articles
303	recently posted to the comp.lang.perl.misc newsgroup and the perl
304	bug database at http://rt.perl.org/perlbug/ . There may also be
305	information at http://www.perl.org/ , the Perl Home Page.
306
307	If you believe you have an unreported bug, please run the B<perlbug>
308	program included with your release. Be sure to trim your bug down
309	to a tiny but sufficient test case. Your bug report, along with the
310	output of C<perl -V>, will be sent off to perlbug@perl.org to be
311	analysed by the Perl porting team.
312
313	If the bug you are reporting has security implications, which make it
314	inappropriate to send to a publicly archived mailing list, then please send
315	it to perl5-security-report@perl.org. This points to a closed subscription
316	unarchived mailing list, which includes all the core committers, who be able
317	to help assess the impact of issues, figure out a resolution, and help
318	co-ordinate the release of patches to mitigate or fix the problem across all
319	platforms on which Perl is supported. Please only use this address for
320	security issues in the Perl core, not for modules independently
321	distributed on CPAN.
322
323	=head1 SEE ALSO
324
325	The F<Changes> file for an explanation of how to view exhaustive details
326	on what changed.
327
328	The F<INSTALL> file for how to build Perl.
329
330	The F<README> file for general stuff.
331
332	The F<Artistic> and F<Copying> files for copyright information.
333
334	=cut