[p5sagit/p5-mst-13.2.git] / pod / perl592delta.pod

=head1 NAME

perldelta - what is new for perl v5.9.2

=head1 DESCRIPTION

This document describes differences between the 5.9.1 and the 5.9.2
development releases. See L<perl590delta> and L<perl591delta> for the
differences between 5.8.0 and 5.9.1.

=head1 Incompatible Changes

=head2 Packing and UTF-8 strings

The semantics of pack() and unpack() regarding UTF-8-encoded data has been
changed. Processing is now by default character per character instead of
byte per byte on the underlying encoding. Notably, code that used things
like C<pack("a*", $string)> to see through the encoding of string will now
simply get back the original $string. Packed strings can also get upgraded
during processing when you store upgraded characters. You can get the old
behaviour by using C<use bytes>.

To be consistent with pack(), the C<C0> in unpack() templates indicates
that the data is to be processed in character mode, i.e. character by
character; at the contrary, C<U0> in unpack() indicates UTF-8 mode, where
the packed string is processed in its UTF-8-encoded Unicode form on a byte
by byte basis. This is reversed with regard to perl 5.8.X.

Moreover, C<C0> and C<U0> can also be used in pack() templates to specify
respectively character and byte modes.

C<C0> and C<U0> in the middle of a pack or unpack format now switch to the
specified encoding mode, honoring parens grouping. Previously, parens were
ignored.

Also, there is a new pack() character format, C<W>, which is intended to
replace the old C<C>. C<C> is kept for unsigned chars coded as bytes in
the strings internal representation. C<W> represents unsigned (logical)
character values, which can be greater than 255. It is therefore more
robust when dealing with potentially UTF-8-encoded data (as C<C> will wrap
values outside the range 0..255, and not respect the string encoding).

In practice, that means that pack formats are now encoding-neutral, except
C<C>.

For consistency, C<A> in unpack() format now trims all Unicode whitespace
from the end of the string. Before perl 5.9.2, it used to strip only the
classical ASCII space characters.

=head2 The -C option can no longer be used on the #! line

It wasn't working anyway.

=head1 Core Enhancements

=head2 Regexp debug flags

A new variable, ${^RE_DEBUG_FLAGS}, controls what debug flags are in
effect for the regular expression engine when running under C<use re
"debug">. See L<re> for details.

=head1 Modules and Pragmata

=head2 New modules

=over 4

=item *

C<Module::CoreList>, by Richard Clamp, is a small handy module that tells
you what versions of core modules ship with any versions of Perl 5. It
comes with a command-line frontend, C<corelist>.

=back

=head2 Updated And Improved Modules and Pragmata

=head1 Utility Changes

=over 4

=item *

The C<corelist> utility is now installed with perl (see L</"New Modules">
above).

=item *

C<h2ph> and C<h2xs> have been made a bit more robust with regard to
"modern" C code.

=back

=head1 Documentation

=head1 Performance Enhancements

=head2 Trie optimization for regexp engine

The regexp engine is now able to factorize common prefixes and suffixes in
regular expressions. A new special variable, ${^RE_TRIE_MAXBUF}, has been
added to fine tune this optimization.

=head1 Installation and Configuration Improvements

=head1 Selected Bug Fixes

=head1 New or Changed Diagnostics

The warning I<Newline in left-justified string> has been removed.

The error I<Too late for "-T" option> has been reformulated to be more
descriptive.

There is a new compilation error, I<Illegal declaration of subroutine>.

=head1 Changed Internals

=head1 Known Problems

=head2 Platform Specific Problems

=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://bugs.perl.org/ .  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.

=head1 SEE ALSO

The F<Changes> file for 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
e0eb806d	1	=head1 NAME
	2
	3	perldelta - what is new for perl v5.9.2
	4
	5	=head1 DESCRIPTION
	6
	7	This document describes differences between the 5.9.1 and the 5.9.2
fa11829f	8	development releases. See L<perl590delta> and L<perl591delta> for the
e0eb806d	9	differences between 5.8.0 and 5.9.1.
	10
	11	=head1 Incompatible Changes
	12
a8cf0b1d	13	=head2 Packing and UTF-8 strings
	14
	15	The semantics of pack() and unpack() regarding UTF-8-encoded data has been
f1aa04aa	16	changed. Processing is now by default character per character instead of
	17	byte per byte on the underlying encoding. Notably, code that used things
	18	like C<pack("a*", $string)> to see through the encoding of string will now
	19	simply get back the original $string. Packed strings can also get upgraded
	20	during processing when you store upgraded characters. You can get the old
	21	behaviour by using C<use bytes>.
a8cf0b1d	22
	23	To be consistent with pack(), the C<C0> in unpack() templates indicates
	24	that the data is to be processed in character mode, i.e. character by
	25	character; at the contrary, C<U0> in unpack() indicates UTF-8 mode, where
	26	the packed string is processed in its UTF-8-encoded Unicode form on a byte
	27	by byte basis. This is reversed with regard to perl 5.8.X.
	28
	29	Moreover, C<C0> and C<U0> can also be used in pack() templates to specify
	30	respectively character and byte modes.
	31
f1aa04aa	32	C<C0> and C<U0> in the middle of a pack or unpack format now switch to the
	33	specified encoding mode, honoring parens grouping. Previously, parens were
	34	ignored.
a8cf0b1d	35
a8cf0b1d	36	Also, there is a new pack() character format, C<W>, which is intended to
f1aa04aa	37	replace the old C<C>. C<C> is kept for unsigned chars coded as bytes in
	38	the strings internal representation. C<W> represents unsigned (logical)
	39	character values, which can be greater than 255. It is therefore more
	40	robust when dealing with potentially UTF-8-encoded data (as C<C> will wrap
	41	values outside the range 0..255, and not respect the string encoding).
a8cf0b1d	42
	43	In practice, that means that pack formats are now encoding-neutral, except
	44	C<C>.
	45
1cdd6bcc	46	For consistency, C<A> in unpack() format now trims all Unicode whitespace
	47	from the end of the string. Before perl 5.9.2, it used to strip only the
	48	classical ASCII space characters.
	49
3911fe8f	50	=head2 The -C option can no longer be used on the #! line
	51
	52	It wasn't working anyway.
	53
e0eb806d	54	=head1 Core Enhancements
e0eb806d	55
1cdd6bcc	56	=head2 Regexp debug flags
	57
	58	A new variable, ${^RE_DEBUG_FLAGS}, controls what debug flags are in
	59	effect for the regular expression engine when running under C<use re
	60	"debug">. See L<re> for details.
	61
e0eb806d	62	=head1 Modules and Pragmata
e0eb806d	63
3911fe8f	64	=head2 New modules
	65
	66	=over 4
	67
	68	=item *
	69
	70	C<Module::CoreList>, by Richard Clamp, is a small handy module that tells
	71	you what versions of core modules ship with any versions of Perl 5. It
	72	comes with a command-line frontend, C<corelist>.
	73
	74	=back
	75
	76	=head2 Updated And Improved Modules and Pragmata
	77
e0eb806d	78	=head1 Utility Changes
e0eb806d	79
3911fe8f	80	=over 4
	81
	82	=item *
	83
	84	The C<corelist> utility is now installed with perl (see L</"New Modules">
	85	above).
	86
	87	=item *
	88
	89	C<h2ph> and C<h2xs> have been made a bit more robust with regard to
	90	"modern" C code.
	91
	92	=back
	93
e0eb806d	94	=head1 Documentation
	95
	96	=head1 Performance Enhancements
	97
1cdd6bcc	98	=head2 Trie optimization for regexp engine
	99
	100	The regexp engine is now able to factorize common prefixes and suffixes in
0111c4fd	101	regular expressions. A new special variable, ${^RE_TRIE_MAXBUF}, has been
1cdd6bcc	102	added to fine tune this optimization.
1cdd6bcc	103
e0eb806d	104	=head1 Installation and Configuration Improvements
	105
	106	=head1 Selected Bug Fixes
	107
	108	=head1 New or Changed Diagnostics
	109
3911fe8f	110	The warning I<Newline in left-justified string> has been removed.
	111
	112	The error I<Too late for "-T" option> has been reformulated to be more
	113	descriptive.
	114
	115	There is a new compilation error, I<Illegal declaration of subroutine>.
	116
e0eb806d	117	=head1 Changed Internals
	118
	119	=head1 Known Problems
	120
	121	=head2 Platform Specific Problems
	122
	123	=head1 Reporting Bugs
	124
	125	If you find what you think is a bug, you might check the articles
	126	recently posted to the comp.lang.perl.misc newsgroup and the perl
	127	bug database at http://bugs.perl.org/ . There may also be
	128	information at http://www.perl.org/ , the Perl Home Page.
	129
	130	If you believe you have an unreported bug, please run the B<perlbug>
	131	program included with your release. Be sure to trim your bug down
	132	to a tiny but sufficient test case. Your bug report, along with the
	133	output of C<perl -V>, will be sent off to perlbug@perl.org to be
	134	analysed by the Perl porting team.
	135
	136	=head1 SEE ALSO
	137
	138	The F<Changes> file for exhaustive details on what changed.
	139
	140	The F<INSTALL> file for how to build Perl.
	141
	142	The F<README> file for general stuff.
	143
	144	The F<Artistic> and F<Copying> files for copyright information.
	145
	146	=cut