[p5sagit/p5-mst-13.2.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 meant that these constructions were 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 meant 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) then
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.

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 APIs for more internals

The lowest layers of the lexer and parts of the pad system now have C
APIs available to XS extensions. These are necessary to support proper
use of pluggable keywords, but have other uses too. The new APIs are
experimental, and only cover a small proportion of what would be necessary
to take full advantage of the core's facilities in these areas. It is
intended that the Perl 5.13 development cycle will see the addition of
a full range of clean, supported interfaces.

=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

=over 4

=item *

Reversing an array to itself (as in C<@a = reverse @a>) in void context now
happens in-place and is several orders of magnitude faster than it used to be.
It will also preserve non-existent elements whenever possible, i.e. for non
magical arrays or tied arrays with C<EXISTS> and C<DELETE> methods.

=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	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
c54f4355	20	An accident of Perl's parser meant that these constructions were all equivalent:
d5114285	21
d83f38d8	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
c54f4355	35	As is, this meant that C<:=> cannot be used as a new token, without silently
d83f38d8	36	changing the meaning of existing code. Hence that particular form is now
d83f38d8	37	deprecated, and will become a syntax error. If it is absolutely necessary to
c54f4355	38	have empty attribute lists (for example, because of a code generator) then
d83f38d8	39	avoid the warning by adding a space before the C<=>.
d5114285	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	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	55	=head2 Pluggable keywords
	56
	57	Extension modules can now cleanly hook into the Perl parser to define new
c54f4355	58	kinds of keyword-headed expression and compound statement. The syntax
c54f4355	59	following the keyword is defined entirely by the extension. This allow
88e1f1a2	60	a completely non-Perl sublanguage to be parsed inline, with the right
c54f4355	61	ops cleanly generated. This feature is currently considered experimental.
88e1f1a2	62
c54f4355	63	See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core source
88e1f1a2	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.
	68
580561a3	69	=head2 APIs for more internals
	70
	71	The lowest layers of the lexer and parts of the pad system now have C
c54f4355	72	APIs available to XS extensions. These are necessary to support proper
c54f4355	73	use of pluggable keywords, but have other uses too. The new APIs are
580561a3	74	experimental, and only cover a small proportion of what would be necessary
c54f4355	75	to take full advantage of the core's facilities in these areas. It is
580561a3	76	intended that the Perl 5.13 development cycle will see the addition of
	77	a full range of clean, supported interfaces.
	78
f7461760	79	=head2 Overridable function lookup
f7461760	80
c54f4355	81	Where an extension module hooks the creation of rv2cv ops to modify
f7461760	82	the subroutine lookup process, this now works correctly for bareword
c54f4355	83	subroutine calls. This means that prototypes on subroutines referenced
c54f4355	84	this way will be processed correctly. (Previously bareword subroutine
f7461760	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.)
	88
d5114285	89	=head1 New Platforms
	90
	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
	94	source tree.
	95
	96	=head1 Modules and Pragmata
	97
	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.
	103
	104	=head2 New Modules and Pragmata
	105
	106	=over 4
	107
	108	=item C<XXX>
	109
	110	XXX
	111
	112	=back
	113
	114	=head2 Pragmata Changes
	115
	116	=over 4
	117
	118	=item C<XXX>
	119
	120	XXX
	121
	122	=back
	123
	124	=head2 Updated Modules
	125
	126	=over 4
	127
	128	=item C<XXX>
	129
	130	XXX
	131
	132	=back
	133
	134	=head1 Utility Changes
	135
	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>.
	138
	139	=over 4
	140
	141	=item F<XXX>
	142
	143	XXX
	144
	145	=back
	146
	147	=head1 New Documentation
	148
	149	XXX Changes which create B<new> files in F<pod/> go here.
	150
	151	=over 4
	152
153	=item L<XXX>
154
155	XXX
156
157	=back
158
159	=head1 Changes to Existing Documentation
160
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>.
163
d5114285	164	=head1 Performance Enhancements
d5114285	165
d5114285	166	=over 4
	167
	168	=item *
	169
437d4214	170	Reversing an array to itself (as in C<@a = reverse @a>) in void context now
	171	happens in-place and is several orders of magnitude faster than it used to be.
	172	It will also preserve non-existent elements whenever possible, i.e. for non
	173	magical arrays or tied arrays with C<EXISTS> and C<DELETE> methods.
d5114285	174
	175	=back
	176
	177	=head1 Installation and Configuration Improvements
	178
	179	XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
	180	go here.
	181
	182	=head2 Configuration improvements
	183
	184	XXX
	185
	186	=head2 Compilation improvements
	187
	188	XXX
	189
	190	=head2 Platform Specific Changes
	191
	192	=over 4
	193
	194	=item XXX-some-platform
	195
	196	XXX
	197
	198	=back
	199
	200	=head1 Selected Bug Fixes
	201
	202	XXX Important bug fixes in the core language are summarised here.
	203	Bug fixes in files in F<ext/> and F<lib/> are best summarised in
	204	L</Modules and Pragmata>.
	205
	206	=over 4
	207
	208	=item *
	209
	210	XXX
	211
	212	=back
	213
	214	=head1 New or Changed Diagnostics
	215
	216	XXX New or changed warnings emitted by the core's C<C> code go here.
	217
	218	=over 4
	219
	220	=item C<XXX>
	221
	222	XXX
	223
	224	=back
	225
	226	=head1 Changed Internals
	227
d5114285	228	=over 4
	229
	230	=item *
	231
879d0c72	232	C<Perl_pmflag> has been removed from the public API. Calling it now generates
	233	a deprecation warning, and it will be removed in a future release. Although
	234	listed as part of the API, it was never documented, and only ever used in
	235	F<toke.c>, and prior to 5.10, F<regcomp.c>. In core, it has been replaced by a
	236	static function.
d5114285	237
	238	=back
	239
	240	=head1 New Tests
	241
	242	XXX Changes which create B<new> files in F<t/> go here. Changes to
	243	existing files in F<t/> aren't worth summarising, although the bugs that
	244	they represent may be.
	245
	246	=over 4
	247
	248	=item F<XXX>
	249
	250	XXX
	251
	252	=back
	253
	254	=head1 Known Problems
	255
	256	XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
	257	tests that had to be C<TODO>ed for the release would be noted here, unless
	258	they were specific to a particular platform (see below).
	259
	260	This is a list of some significant unfixed bugs, which are regressions
	261	from either 5.10.1 or 5.11.1.
	262
	263	=over 4
	264
	265	=item *
	266
	267	XXX
	268
	269	=back
	270
	271	=head1 Deprecations
	272
	273	XXX Add any new known deprecations here.
	274
	275	The following items are now deprecated.
	276
	277	=over 4
	278
	279	=item *
	280
	281	XXX
	282
	283	=back
	284
	285	=head1 Platform Specific Notes
	286
	287	XXX Any changes specific to a particular platform. VMS and Win32 are the usual
	288	stars here. It's probably best to group changes under the same section layout
	289	as the main perldelta
	290
	291	=head1 Obituary
	292
	293	XXX If any significant core contributor has died, we've added a short obituary
	294	here.
	295
	296	=head1 Acknowledgements
	297
	298	XXX The list of people to thank goes here.
	299
	300
301	=head1 Reporting Bugs
302
303	If you find what you think is a bug, you might check the articles
304	recently posted to the comp.lang.perl.misc newsgroup and the perl
305	bug database at http://rt.perl.org/perlbug/ . There may also be
306	information at http://www.perl.org/ , the Perl Home Page.
307
308	If you believe you have an unreported bug, please run the B<perlbug>
309	program included with your release. Be sure to trim your bug down
310	to a tiny but sufficient test case. Your bug report, along with the
311	output of C<perl -V>, will be sent off to perlbug@perl.org to be
312	analysed by the Perl porting team.
313
314	If the bug you are reporting has security implications, which make it
315	inappropriate to send to a publicly archived mailing list, then please send
316	it to perl5-security-report@perl.org. This points to a closed subscription
317	unarchived mailing list, which includes all the core committers, who be able
318	to help assess the impact of issues, figure out a resolution, and help
319	co-ordinate the release of patches to mitigate or fix the problem across all
320	platforms on which Perl is supported. Please only use this address for
321	security issues in the Perl core, not for modules independently
322	distributed on CPAN.
323
324	=head1 SEE ALSO
325
326	The F<Changes> file for an explanation of how to view exhaustive details
327	on what changed.
328
329	The F<INSTALL> file for how to build Perl.
330
331	The F<README> file for general stuff.
332
333	The F<Artistic> and F<Copying> files for copyright information.
334
335	=cut