=head1 NAME
-perldelta - what is new for perl v5.9.2
+perl592delta - what is new for perl v5.9.2
=head1 DESCRIPTION
=head2 Packing and UTF-8 strings
The semantics of pack() and unpack() regarding UTF-8-encoded data has been
-clarified. B<The character mode is now the default.> Notably, code that
-uses C<pack("a*", $string)> to see through the encoding of string will now
-simply return $string.
+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
+character; on 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 format now switch to the specified
-encoding mode, honoring parens grouping. Previously, parens were ignored.
+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 on eight bits.
-C<W> represents unsigned 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).
+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 Miscellaneous
+
+The internal dump output has been improved, so that non-printable characters
+such as newline and backspace are output in C<\x> notation, rather than
+octal.
+
+The B<-C> option can no longer be used on the C<#!> line. It wasn't
+working there anyway.
+
=head1 Core Enhancements
+=head2 Malloc wrapping
+
+Perl can now be built to detect attempts to assign pathologically large chunks
+of memory. Previously such assignments would suffer from integer wrap-around
+during size calculations causing a misallocation, which would crash perl, and
+could theoretically be used for "stack smashing" attacks. The wrapping
+defaults to enabled on platforms where we know it works (most AIX
+configurations, BSDi, Darwin, DEC OSF/1, FreeBSD, HP-UX, GNU Linux, OpenBSD,
+Solaris, VMS and most Win32 compilers) and defaults to disabled on other
+platforms.
+
+=head2 Unicode Character Database 4.0.1
+
+The copy of the Unicode Character Database included in Perl 5.9 has
+been updated to 4.0.1 from 4.0.0.
+
+=head2 suidperl less insecure
+
+Paul Szabo has analysed and patched C<suidperl> to remove existing known
+insecurities. Currently there are no known holes in C<suidperl>, but previous
+experience shows that we cannot be confident that these were the last. You may
+no longer invoke the set uid perl directly, so to preserve backwards
+compatibility with scripts that invoke #!/usr/bin/suidperl the only set uid
+binary is now C<sperl5.9.>I<n> (C<sperl5.9.2> for this release). C<suidperl>
+is installed as a hard link to C<perl>; both C<suidperl> and C<perl> will
+invoke C<sperl5.9.2> automatically the set uid binary, so this change should
+be completely transparent.
+
+For new projects the core perl team would strongly recommend that you use
+dedicated, single purpose security tools such as C<sudo> in preference to
+C<suidperl>.
+
+=head2 PERLIO_DEBUG
+
+The C<PERLIO_DEBUG> environment variable has no longer any effect for
+setuid scripts and for scripts run with B<-T>.
+
+Moreover, with a thread-enabled perl, using C<PERLIO_DEBUG> could lead to
+an internal buffer overflow. This has been fixed.
+
+=head2 Formats
+
+In addition to bug fixes, C<format>'s features have been enhanced. See
+L<perlform>.
+
+=head2 Unicode Character Classes
+
+Perl's regular expression engine now contains support for matching on the
+intersection of two Unicode character classes. You can also now refer to
+user-defined character classes from within other user defined character
+classes.
+
+=head2 Byte-order modifiers for pack() and unpack()
+
+There are two new byte-order modifiers, C<E<gt>> (big-endian) and C<E<lt>>
+(little-endian), that can be appended to most pack() and unpack() template
+characters and groups to force a certain byte-order for that type or group.
+See L<perlfunc/pack> and L<perlpacktut> for details.
+
+=head2 Byte count feature in pack()
+
+A new pack() template character, C<".">, returns the number of characters
+read so far.
+
+=head2 New variables
+
+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.
+
+A new variable ${^UTF8LOCALE} indicates where a UTF-8 locale was detected
+by perl at startup.
+
=head1 Modules and Pragmata
+=head2 New modules
+
+=over 4
+
+=item *
+
+C<encoding::warnings>, by Audrey Tang, is a module to emit warnings
+whenever an ASCII character string containing high-bit bytes is implicitly
+converted into UTF-8.
+
+=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
+
+Dual-lived modules have been updated to be kept up-to-date with respect to
+CPAN.
+
+The dual-lived modules which contain an C<_> in their version number are
+actually I<ahead> of the corresponding CPAN release.
+
+=over 4
+
+=item B::Concise
+
+C<B::Concise> was significantly improved.
+
+=item Socket
+
+There is experimental support for Linux abstract Unix domain sockets.
+
+=item Sys::Syslog
+
+C<syslog()> can now use numeric constants for facility names and priorities,
+in addition to strings.
+
+=item threads
+
+Detached threads are now also supported on Windows.
+
+=back
+
=head1 Utility Changes
-=head1 Documentation
+=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.
+
+=item *
+
+Several bugs have been fixed in C<find2perl>, regarding C<-exec> and
+C<-eval>. Also the options C<-path>, C<-ipath> and C<-iname> have been
+added.
+
+=item *
+
+The Perl debugger can now save all debugger commands for sourcing later;
+notably, it can now emulate stepping backwards, by restarting and
+rerunning all bar the last command from a saved command history.
+
+It can also display the parent inheritance tree of a given class.
+
+Perl has a new -dt command-line flag, which enables threads support in the
+debugger.
+
+=back
=head1 Performance Enhancements
+=over 4
+
+=item *
+
+Unicode case mappings (C</i>, C<lc>, C<uc>, etc) are faster.
+
+=item *
+
+C<@a = sort @a> was optimized to do in-place sort. Likewise, C<reverse
+sort ...> is now optimized to sort in reverse, avoiding the generation of
+a temporary intermediate list.
+
+=item *
+
+Unnecessary assignments are optimised away in
+
+ my $s = undef;
+ my @a = ();
+ my %h = ();
+
+=item *
+
+C<map> in scalar context is now optimized.
+
+=item *
+
+The regexp engine now implements the trie optimization : it's able to
+factorize common prefixes and suffixes in regular expressions. A new
+special variable, ${^RE_TRIE_MAXBUF}, has been added to fine-tune this
+optimization.
+
+=back
+
=head1 Installation and Configuration Improvements
+Run-time customization of @INC can be enabled by passing the
+C<-Dusesitecustomize> flag to configure. When enabled, this will make perl
+run F<$sitelibexp/sitecustomize.pl> before anything else. This script can
+then be set up to add additional entries to @INC.
+
+There is alpha support for relocatable @INC entries.
+
+Perl should build on Interix and on GNU/kFreeBSD.
+
=head1 Selected Bug Fixes
+Most of those bugs were reported in the perl 5.8.x maintenance track.
+Notably, quite a few utf8 bugs were fixed, and several memory leaks were
+suppressed. The perl58Xdelta manpages have more details on them.
+
+Development-only bug fixes include :
+
+C<$Foo::_> was wrongly forced as C<$main::_>.
+
=head1 New or Changed Diagnostics
+A new warning, C<!=~ should be !~>, is emitted to prevent this misspelling
+of the non-matching operator.
+
+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>,
+for an obscure case of syntax errors.
+
+The diagnostic output of Carp has been changed slightly, to add a space after
+the comma between arguments. This makes it much easier for tools such as
+web browsers to wrap it, but might confuse any automatic tools which perform
+detailed parsing of Carp output.
+
+C<perl -V> has several improvements, making it more useable from shell
+scripts to get the value of configuration variables. See L<perlrun> for
+details.
+
=head1 Changed Internals
+The perl core has been refactored and reorganised in several places.
+In short, this release will not be binary compatible with any previous
+perl release.
+
=head1 Known Problems
-=head2 Platform Specific Problems
+For threaded builds, F<ext/threads/shared/t/wait.t> has been reported to
+fail some tests on HP-UX 10.20.
+
+Net::Ping might fail some tests on HP-UX 11.00 with the latest OS
+upgrades.
+
+F<t/io/dup.t>, F<t/io/open.t> and F<lib/ExtUtils/t/Constant.t> fail some
+tests on some BSD flavours.
+
+=head1 Plans for the next release
+
+The current plan for perl 5.9.3 is to add CPANPLUS as a core module.
+More regular expression optimizations are also in the works.
+
+It is planned to release a development version of perl more frequently,
+i.e. each time something major changes.
=head1 Reporting Bugs
https://perl5.git.perl.org / perl5.git / blobdiff