=head1 NAME
-perldelta - what's new for perl v5.7.0
+perldelta - what is new for perl v5.8.0
=head1 DESCRIPTION
-This document describes differences between the 5.6.0 release and
-the 5.7.0 release.
+This document describes differences between the 5.6.0 release and the
+5.8.0 release.
-=head1 Security Vulnerability Closed
+=head1 Incompatible Changes
-A potential security vulnerability in the optional suidperl component
-of Perl has been identified. suidperl is neither built nor installed
-by default. As of August the 20th, 2000, the only known vulnerable
-platform is Linux, most likely all Linux distributions. CERT and
-various vendors have been alerted about the vulnerability.
+=head2 64-bit platforms and malloc
-The problem was caused by Perl trying to report a suspected security
-exploit attempt using an external program, /bin/mail. On Linux
-platforms the /bin/mail program had an undocumented feature which gave
-access to a root shell, resulting in a serious compromise instead of
-reporting the exploit attempt. If you don't have /bin/mail, or if you
-have 'safe setuid scripts', or if suidperl is not installed, you
-are safe.
+If your pointers are 64 bits wide, the Perl malloc is no more being
+used because it simply does not work with 8-byte pointers. Also,
+usually the system mallocs on such platforms are much better optimized
+for such large memory models than the Perl malloc. Such platforms
+include 64-bit Alpha, MIPS, HPPA, PPC, and Sparc.
-The exploit attempt reporting feature has been completely removed from
-the Perl 5.7.0 release, so that particular vulnerability isn't there
-anymore. However, further security vulnerabilities are,
-unfortunately, always possible. The suidperl code is being reviewed
-and if deemed too risky to continue to be supported, it may be
-completely removed from future releases. In any case, suidperl should
-only be used by security experts who know exactly what they are doing
-and why they are using suidperl instead of some other solution such as
-sudo (see http://www.courtesan.com/sudo/).
+=head2 AIX Dynaloading
-=head1 Incompatible Changes
+The AIX dynaloading now uses in AIX releases 4.3 and newer the native
+dlopen interface of AIX instead of the old emulated interface. This
+change will probably break backward compatibility with compiled
+modules. The change was made to make Perl more compliant with other
+applications like modperl which are using the AIX native interface.
-=over 4
+=head2 Socket Extension Dynamic in VMS
-=item *
+The Socket extension is now dynamically loaded instead of being
+statically built in. This may or may not be a problem with ancient
+TCP/IP stacks of VMS: we do not know since we weren't able to test
+Perl in such configurations.
+
+=head2 Different Definition of the Unicode Character Classes \p{In...}
+
+As suggested by the Unicode consortium, the Unicode character classes
+now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
+in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
+constructs are used. This has changed the definition of some of those
+character classes.
+
+The difference between scripts and blocks is that scripts are the
+glyphs used by a language or a group of languages, while the blocks
+are more artificial groupings of 256 characters based on the Unicode
+numbering.
+
+In general this change results in more inclusive Unicode character
+classes, but changes to the other direction also do take place:
+for example while the script C<Latin> includes all the Latin
+characters and their various diacritic-adorned versions, it
+does not include the various punctuation or digits (since they
+are not solely C<Latin>).
+
+Changes in the character class semantics may have happened if a script
+and a block happen to have the same name, for example C<Hebrew>.
+In such cases the script wins and C<\p{InHebrew}> now means the script
+definition of Hebrew. The block definition in still available,
+though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
+what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
+of affected character classes, see L<perlunicode/Blocks>.
+
+=head2 Perl Parser Stress Tested
-Arrays now always interpolate into double-quoted strings:
-constructs like "foo@bar" now always assume C<@bar> is an array,
-whether or not the compiler has seen use of C<@bar>.
+The Perl parser has been stress tested using both random input and
+Markov chain input and the few found crashes and lockups have been
+fixed.
+
+=head2 Deprecations
+
+The current user-visible implementation of pseudo-hashes (the weird
+use of the first array element) is deprecated starting from Perl 5.8.0
+and will be removed in Perl 5.10.0, and the feature will be
+implemented differently. Not only is the current interface rather
+ugly, but the current implementation slows down normal array and hash
+use quite noticeably. The C<fields> pragma interface will remain
+available.
+
+The syntaxes C<@a->[...]> and C<@h->{...}> have now been deprecated.
+
+After years of trying the suidperl is considered to be too complex to
+ever be considered truly secure. The suidperl functionality is likely
+to be removed in a future release.
+
+The C<package;> syntax (C<package> without an argument has been
+deprecated. Its semantics were never that clear and its
+implementation even less so. If you have used that feature to
+disallow all but fully qualified variables, C<use strict;> instead.
+
+=over 4
=item *
=item *
+A reference to a reference now stringify as "REF(0x81485ec)" instead
+of "SCALAR(0x81485ec)" in order to be more consistent with the return
+value of ref().
+
+=item *
+
The very dusty examples in the eg/ directory have been removed.
Suggestions for new shiny examples welcome but the main issue is that
the examples need to be documented, tested and (most importantly)
=item *
+The (bogus) escape sequences \8 and \9 now give an optional warning
+("Unrecognized escape passed through"). There is no need to \-escape
+any C<\w> character.
+
+=item *
+
lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
In future releases this may become a fatal error.
the interface was a mistake. Sorry about that. For similar
functionality, see pack('U0', ...) and pack('C0', ...).
+=item *
+
+Although "you shouldn't do that", it was possible to write code that
+depends on Perl's hashed key order (Data::Dumper does this). The new
+algorithm "One-at-a-Time" produces a different hashed key order.
+More details are in L</"Performance Enhancements">.
+
+=item *
+
+The list of filenames from glob() (or <...>) is now by default sorted
+alphabetically to be csh-compliant. (bsd_glob() does still sort platform
+natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
+
=back
=head1 Core Enhancements
+=head2 AUTOLOAD Is Now Lvaluable
+
+AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
+to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
+
+=head2 PerlIO is Now The Default
+
+=over 4
+
+=item *
+
+IO is now by default done via PerlIO rather than system's "stdio".
+PerlIO allows "layers" to be "pushed" onto a file handle to alter the
+handle's behaviour. Layers can be specified at open time via 3-arg
+form of open:
+
+ open($fh,'>:crlf :utf8', $path) || ...
+
+or on already opened handles via extended C<binmode>:
+
+ binmode($fh,':encoding(iso-8859-7)');
+
+The built-in layers are: unix (low level read/write), stdio (as in
+previous Perls), perlio (re-implementation of stdio buffering in a
+portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
+but available on any platform). A mmap layer may be available if
+platform supports it (mostly UNIXes).
+
+Layers to be applied by default may be specified via the 'open' pragma.
+
+See L</"Installation and Configuration Improvements"> for the effects
+of PerlIO on your architecture name.
+
+=item *
+
+File handles can be marked as accepting Perl's internal encoding of Unicode
+(UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
+
+ open($fh,">:utf8","Uni.txt");
+
+Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
+for you since it's not UTF-8 what you will be getting but instead
+UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
+http://www.unicode.org/unicode/reports/tr16/ for more information.
+In future releases this naming may change.
+
+=item *
+
+File handles can translate character encodings from/to Perl's internal
+Unicode form on read/write via the ":encoding()" layer.
+
+=item *
+
+File handles can be opened to "in memory" files held in Perl scalars via:
+
+ open($fh,'>', \$variable) || ...
+
+=item *
+
+Anonymous temporary files are available without need to
+'use FileHandle' or other module via
+
+ open($fh,"+>", undef) || ...
+
+That is a literal undef, not an undefined value.
+
+=item *
+
+The list form of C<open> is now implemented for pipes (at least on UNIX):
+
+ open($fh,"-|", 'cat', '/etc/motd')
+
+creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
+the child process.
+
+=item *
+
+The following builtin functions are now overridable: chop(), chomp(),
+each(), keys(), pop(), push(), shift(), splice(), unshift().
+
+=item *
+
+Formats now support zero-padded decimal fields.
+
+=item *
+
+Perl now tries internally to use integer values in numeric conversions
+and basic arithmetics (+ - * /) if the arguments are integers, and
+tries also to keep the results stored internally as integers.
+This change leads into often slightly faster and always less lossy
+arithmetics. (Previously Perl always preferred floating point numbers
+in its math.)
+
+=item *
+
+The printf() and sprintf() now support parameter reordering using the
+C<%\d+\$> and C<*\d+\$> syntaxes. For example
+
+ print "%2\$s %1\$s\n", "foo", "bar";
+
+will print "bar foo\n"; This feature helps in writing
+internationalised software.
+
+=item *
+
+Unicode in general should be now much more usable. Unicode can be
+used in hash keys, Unicode in regular expressions should work now,
+Unicode in tr/// should work now (though tr/// seems to be a
+particularly tricky to get right, so you have been warned)
+
+=item *
+
+The Unicode Character Database coming with Perl has been upgraded
+to Unicode 3.1. For more information, see http://www.unicode.org/,
+and http://www.unicode.org/unicode/reports/tr27/
+
+For developers interested in enhancing Perl's Unicode capabilities:
+almost all the UCD files are included with the Perl distribution in
+the lib/unicode subdirectory. The most notable omission, for space
+considerations, is the Unihan database.
+
+=item *
+
+The Unicode character classes \p{Blank} and \p{SpacePerl} have been
+added. "Blank" is like C isblank(), that is, it contains only
+"horizontal whitespace" (the space character is, the newline isn't),
+and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
+isn't, since that includes the vertical tabulator character, whereas
+C<\s> doesn't.)
+
+=back
+
+=head2 Signals Are Now Safe
+
+Perl used to be fragile in that signals arriving at inopportune moments
+could corrupt Perl's internal state.
+
+=head2 Understanding of Numbers
+
+In general a lot of fixing has happened in the area of Perl's
+understanding of numbers, both integer and floating point. Since in
+many systems the standard number parsing functions like C<strtoul()>
+and C<atof()> seem to have bugs, Perl tries to work around their
+deficiencies. This results hopefully in more accurate numbers.
+
=over 4
=item *
=item *
-my __PACKAGE__ now works.
+END blocks are now run even if you exit/die in a BEGIN block.
+Internally, the execution of END blocks is now controlled by
+PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
+behaviour for Perl embedders. This will default in 5.10. See
+L<perlembed>.
+
+=item *
+
+Lexicals I: lexicals outside an eval "" weren't resolved
+correctly inside a subroutine definition inside the eval "" if they
+were not already referenced in the top level of the eval""ed code.
+
+=item *
+
+Lexicals II: lexicals leaked at file scope into subroutines that
+were declared before the lexicals.
+
+=item *
+
+Lvalue subroutines can now return C<undef> in list context.
+
+=item *
+
+A new special regular expression variable has been introduced:
+C<$^N>, which contains the most-recently closed group (submatch).
=item *
=item *
+my __PACKAGE__ $obj now works.
+
+=item *
+
prototype(\&) is now available.
=item *
-There is now an UNTIE method.
+Right-hand side magic (GMAGIC) could in many cases such as string
+concatenation be invoked too many times.
+
+=item *
+
+The rules for allowing underscores (underbars) in numeric constants
+have been relaxed and simplified: now you can have an underscore
+simply B<between digits>.
+
+=item *
+
+An UNTIE method is now available.
+
+=item *
+
+L<utime> now supports C<utime undef, undef, @files> to change the
+file timestamps to the current time.
+
+=item *
+
+C<eval "v200"> now works.
=back
=item *
-File::Temp allows one to create temporary files and directories in an
-easy, portable, and secure way.
+C<Attribute::Handlers> allows a class to define attribute handlers.
+
+ package MyPack;
+ use Attribute::Handlers;
+ sub Wolf :ATTR(SCALAR) { print "howl!\n" }
+
+ # later, in some package using or inheriting from MyPack...
+
+ my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
+
+Both variables and routines can have attribute handlers. Handlers can
+be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
+exact compilation phase (BEGIN, CHECK, INIT, or END).
=item *
-Storable gives persistence to Perl data structures by allowing the
-storage and retrieval of Perl data to and from files in a fast and
-compact binary format.
+B<B::Concise> is a new compiler backend for walking the Perl syntax
+tree, printing concise info about ops, from Stephen McCamant. The
+output is highly customisable. See L<B::Concise>.
-=back
+=item *
-=head2 Updated And Improved Modules and Pragmata
+C<Class::ISA> for reporting the search path for a class's ISA tree,
+by Sean Burke, has been added. See L<Class::ISA>.
-=over 4
+=item *
+
+C<Cwd> has now a split personality: if possible, an XS extension is
+used, (this will hopefully be faster, more secure, and more robust)
+but if not possible, the familiar Perl implementation is used.
=item *
-The following independently supported modules have been updated to
-newer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
-the podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
+C<Digest>, frontend module for calculating digests (checksums), from
+Gisle Aas, has been added. See L<Digest>.
=item *
-Bug fixes and minor enhancements have been applied to B::Deparse,
-Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
-Math::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
-Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
-pragma.
+C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
+RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
+
+ use Digest::MD5 'md5_hex';
+
+ $digest = md5_hex("Thirsty Camel");
+
+ print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
+
+NOTE: the C<MD5> backward compatibility module is deliberately not
+included since its use is discouraged.
=item *
-The attributes::reftype() now works on tied arguments.
+C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
+between different character encodings. Support for Unicode,
+ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
+compiled in to the module. Several other encodings (like Japanese,
+Chinese, and MacIntosh encodings) are included and will be loaded at
+runtime. See L<Encode>.
+
+Any encoding supported by Encode module is also available to the
+":encoding()" layer if PerlIO is used.
=item *
-AutoLoader can now be disabled with C<no AutoLoader;>,
+C<I18N::Langinfo> can be use to query locale information.
+See L<I18N::Langinfo>.
=item *
-The English module can now be used without the infamous performance
-hit by saying
+C<I18N::LangTags> has functions for dealing with RFC3066-style
+language tags, by Sean Burke. See <I18N::LangTags>.
- use English '-no_performance_hit';
+=item *
-(Assuming, of course, that one doesn't need the troublesome variables
-C<$`>, C<$&>, or C<$'>.) Also, introduce C<@LAST_MATCH_START> and
-C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
+C<ExtUtils::Constant> is a new tool for extension writers for
+generating XS code to import C header constants, by Nicholas Clark.
+See L<ExtUtils::Constant>.
=item *
-File::Find now has pre- and post-processing callbacks. It also
-correctly changes directories when chasing symbolic links. Callbacks
-(naughtily) exiting with "next;" instead of "return;" now work.
+C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
+from Damian Conway. See L<Filter::Simple>.
+
+ # in MyFilter.pm:
+
+ package MyFilter;
+
+ use Filter::Simple sub {
+ while (my ($from, $to) = splice @_, 0, 2) {
+ s/$from/$to/g;
+ }
+ };
+
+ 1;
+
+ # in user's code:
+
+ use MyFilter qr/red/ => 'green';
+
+ print "red\n"; # this code is filtered, will print "green\n"
+ print "bored\n"; # this code is filtered, will print "bogreen\n"
+
+ no MyFilter;
+
+ print "red\n"; # this code is not filtered, will print "red\n"
=item *
-File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
-prototype mismatch with CORE::glob().
+C<File::Temp> allows one to create temporary files and directories in
+an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
=item *
-IPC::Open3 now allows the use of numeric file descriptors.
+C<Filter::Util::Call> provides you with the framework to write
+I<Source Filters> in Perl, from Paul Marquess. For most uses the
+frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
=item *
-use lib now works identically to @INC. Removing directories
-with 'no lib' now works.
+L<libnet> is a collection of perl5 modules related to network
+programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
+L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
+
+Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
=item *
-C<%INC> now localised in a Safe compartment so that use/require work.
+C<List::Util> is a selection of general-utility list subroutines, like
+sum(), min(), first(), and shuffle(), by Graham barr. See L<List::Util>.
=item *
-The Shell module now has an OO interface.
+C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
+C<Locale::Language>, from Neil Bowers, have been added. They provide the
+codes for various locale standards, such as "fr" for France, "usd" for
+US Dollar, and "jp" for Japanese.
+
+ use Locale::Country;
+
+ $country = code2country('jp'); # $country gets 'Japan'
+ $code = country2code('Norway'); # $code gets 'no'
+
+See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
+and L<Locale::Language>.
=item *
-=back
+C<Locale::Maketext> is localization framework from Sean Burke. See
+L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
+article about software localization, originally published in The Perl
+Journal #13, republished here with kind permission.
-=head1 Utility Changes
+=item *
-=over 4
+C<Memoize> can make your functions faster by trading space for time,
+from Mark-Jason Dominus. See L<Memoize>.
=item *
-The Emacs perl mode (emacs/cperl-mode.el) has been updated to version 4.31.
+C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
+as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
+Extensions)>.
+
+ use MIME::Base64;
+
+ $encoded = encode_base64('Aladdin:open sesame');
+ $decoded = decode_base64($encoded);
+
+ print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
+
+See L<MIME::Base64>.
=item *
-Perlbug is now much more robust. It also sends the bug report to perl.org,
-not perl.com.
+C<MIME::QuotedPrint> allows you to encode data in quoted-printable
+encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
+Extensions)>, from Gisle Aas.
+
+ use MIME::QuotedPrint;
+
+ $encoded = encode_qp("Smiley in Unicode: \x{263a}");
+ $decoded = decode_qp($encoded);
+
+ print $encoded, "\n"; # "Smiley in Unicode: =263A"
+
+MIME::QuotedPrint has been enhanced to provide the basic methods
+necessary to use it with PerlIO::Via as in :
+
+ use MIME::QuotedPrint;
+ open($fh,">Via(MIME::QuotedPrint)",$path)
+
+See L<MIME::QuotedPrint>.
=item *
-The perlcc utility has been rewritten and its user interface (that is,
-command line) is much more like that of the UNIX C compiler, cc.
+C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
+See L<NEXT>.
=item *
-The xsubpp utility for extension writers now understands POD
-documentation embedded in the *.xs files.
+C<PerlIO::Scalar> provides the implementation of IO to "in memory"
+Perl scalars as discussed above, from Nick Ing-Simmons. It also
+serves as an example of a loadable PerlIO layer. Other future
+possibilities include PerlIO::Array and PerlIO::Code.
+See L<PerlIO::Scalar>.
-=back
+=item *
-=head1 New Documentation
+C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
+functionality provided by a class (typically implemented in perl
+code), from Nick Ing-Simmons.
-=over 4
+ use MIME::QuotedPrint;
+ open($fh,">Via(MIME::QuotedPrint)",$path)
+
+This will automatically convert everything output to C<$fh>
+to Quoted-Printable. See L<PerlIO::Via>.
=item *
-perl56delta details the changes between the 5.005 release and the
-5.6.0 release.
+C<Pod::Text::Overstrike>, by Joe Smith, has been added.
+It converts POD data to formatted overstrike text.
+See L<Pod::Text::Overstrike>.
=item *
-perldebtut is a Perl debugging tutorial.
+C<Scalar::Util> is a selection of general-utility scalar subroutines,
+like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
=item *
-perlebcdic contains considerations for running Perl on EBCDIC platforms.
-Note that unfortunately EBCDIC platforms that used to supported back in
-Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
-bring them back to the fold.
+C<Storable> gives persistence to Perl data structures by allowing the
+storage and retrieval of Perl data to and from files in a fast and
+compact binary format, from Raphael Manfredi. See L<Storable>.
=item *
-perlnewmod tells about writing and submitting a new module.
+C<Switch>, from Damian Conway, has been added. Just by saying
+
+ use Switch;
+
+you have C<switch> and C<case> available in Perl.
+
+ use Switch;
+
+ switch ($val) {
+
+ case 1 { print "number 1" }
+ case "a" { print "string a" }
+ case [1..10,42] { print "number in list" }
+ case (@array) { print "number in list" }
+ case /\w+/ { print "pattern" }
+ case qr/\w+/ { print "pattern" }
+ case (%hash) { print "entry in hash" }
+ case (\%hash) { print "entry in hash" }
+ case (\&sub) { print "arg to subroutine" }
+ else { print "previous case not true" }
+ }
+
+See L<Switch>.
=item *
-perlposix-bc explains using Perl on the POSIX-BC platform
-(an EBCDIC mainframe platform).
+C<Test::More> is yet another framework for writing test scripts,
+more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
=item *
-perlretut is a regular expression tutorial.
+C<Test::Simple> has the- basic utilities for writing tests, by Michael
+Schwern. See L<Test::Simple>.
=item *
-perlrequick is a regular expressions quick-start guide.
-Yes, much quicker than perlretut.
+C<Text::Balanced> has been added, for extracting delimited text
+sequences from strings, from Damian Conway.
+
+ use Text::Balanced 'extract_delimited';
+
+ ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
+
+$a will be "'never say never'", $b will be ', he never said'.
+
+In addition to extract_delimited() there are also extract_bracketed(),
+extract_quotelike(), extract_codeblock(), extract_variable(),
+extract_tagged(), extract_multiple(), gen_delimited_pat(), and
+gen_extract_tagged(). With these you can implement rather advanced
+parsing algorithms. See L<Text::Balanced>.
=item *
-perlutil explains the command line utilities packaged with the Perl
-distribution.
+C<threads> is an interface interpreter threads, by Arthur Bergman.
+Interpreter threads (ithreads) is the new thread model introduced in
+Perl 5.6 but then available only as an internal interface for
+extension writers. See L<threads>.
-=back
+=item *
-=head1 Performance Enhancements
+C<threads::shared> allows data sharing for interpreter threads, from
+Arthur Bergman. In the ithreads model any data sharing between
+threads must be explicit, as opposed to the old 5.005 thread model
+where data sharing was implicit. See L<threads::shared>.
-=over 4
+=item *
+
+C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
+references (unlike the standard Tie::RefHash) The module is contained
+within Tie::RefHash, see L<Tie::RefHash>.
=item *
-map() that changes the size of the list should now work faster.
+C<Time::HiRes> provides high resolution timing (ualarm, usleep,
+and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
-=back
+=item *
-=head1 Installation and Configuration Improvements
+C<Unicode::UCD> offers a querying interface to the Unicode Character
+Database. See L<Unicode::UCD>.
-=head2 Generic Improvements
+=item *
+
+C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
+for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
+
+=item *
+
+C<Unicode::Normalize> implements the various Unicode normalization
+forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
+
+=item *
+
+C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
+typemaps. Nothing gets installed but for extension writers the code
+is worth studying.
+
+=back
+
+=head2 Updated And Improved Modules and Pragmata
=over 4
=item *
-INSTALL now explains how you can configure perl to use 64-bit
-integers even on non-64-bit platforms.
+The following independently supported modules have been updated to the
+newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
+Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
+(Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
+Term::ANSIColor, Test, Text-Tabs+Wrap.
=item *
-Policy.sh policy change: if you are reusing a Policy.sh file (see
-INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
-Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
-them will now be changed to the new prefix, /foo/bar. (Previously
-only $prefix changed.) If you do not like this new behaviour,
-specify prefix, siteprefix, and vendorprefix explicitly.
+The attributes::reftype() now works on tied arguments.
=item *
-A new optional location for Perl libraries, otherlibdirs, is available.
-It can be used for example for vendor add-ons without disturbing Perl's
-own library directories.
+AutoLoader can now be disabled with C<no AutoLoader;>,
+
+=item *
+
+Data::Dumper has now an option to sort hashes.
+
+=item *
+
+The English module can now be used without the infamous performance
+hit by saying
+
+ use English '-no_performance_hit';
+
+(Assuming, of course, that one doesn't need the troublesome variables
+C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
+C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
+
+=item *
+
+File::Find now has pre- and post-processing callbacks. It also
+correctly changes directories when chasing symbolic links. Callbacks
+(naughtily) exiting with "next;" instead of "return;" now work.
+
+=item *
+
+File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
+prototype mismatch with CORE::glob().
+
+=item *
+
+IPC::Open3 now allows the use of numeric file descriptors.
+
+=item *
+
+use lib now works identically to @INC. Removing directories
+with 'no lib' now works.
+
+=item *
+
+C<%INC> now localised in a Safe compartment so that use/require work.
+
+=item *
+
+The Shell module now has an OO interface.
+
+=item *
+
+B::Deparse has been significantly enhanced. It now can deparse almost
+all of the standard test suite (so that the tests still succeed).
+There is a make target "test.deparse" for trying this out.
+
+=item *
+
+Class::Struct can now define the classes in compile time.
+
+=item *
+
+Class::Struct now assigns the array/hash element if the accessor
+is called with an array/hash element as the B<sole> argument.
+
+=item *
+
+Fcntl, Socket, and Sys::Syslog have been rewritten to use the
+new-style constant dispatch section (see L<ExtUtils::Constant>).
+
+=item *
+
+File::Find is now (again) reentrant. It also has been made
+more portable.
+
+=item *
+
+File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
+the returned list of filenames.
+
+=item *
+
+Devel::Peek now has an interface for the Perl memory statistics
+(this works only if you are using perl's malloc, and if you have
+compiled with debugging).
+
+=item *
+
+IO::Socket has now atmark() method, which returns true if the socket
+is positioned at the out-of-band mark. The method is also exportable
+as a sockatmark() function.
+
+=item *
+
+IO::Socket::INET has support for ReusePort option (if your platform
+supports it). The Reuse option now has an alias, ReuseAddr. For clarity
+you may want to prefer ReuseAddr.
+
+=item *
+
+IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
+that the operating system will make one up.)
+
+=item *
+
+Math::BigFloat and Math::BigInt have undergone much fixing,
+they are now magnitudes faster, and they support various
+bignum libraries such as GMP and PARI as their backends.
+
+=item *
+
+Net::Ping has been enhanced. There is now "external" protocol which
+uses Net::Ping::External module which runs external ping(1) and parses
+the output. An alpha version of Net::Ping::External is available in
+CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
+
+=item *
+
+The C<open> pragma allows layers other than ":raw" and ":crlf" when
+using PerlIO.
+
+=item *
+
+POSIX::sigaction() is now much more flexible and robust.
+You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
+handlers, installing new handlers was not atomic.
+
+=item *
+
+The Test module has been significantly enhanced.
+
+=item *
+
+The C<vars> pragma now supports declaring fully qualified variables.
+(Something that C<our()> does not and will not support.)
+
+=item *
+
+The utf8:: name space (as in the pragma) provides various
+Perl-callable functions to provide low level access to Perl's
+internal Unicode representation. At the moment only length()
+has been implemented.
+
+=back
+
+=head1 Utility Changes
+
+=over 4
+
+=item *
+
+Emacs perl mode (emacs/cperl-mode.el) has been updated to version
+4.31.
+
+=item *
+
+F<emacs/e2ctags.pl> is now much faster.
+
+=item *
+
+h2xs now produces a template README.
+
+=item *
+
+L<h2ph> now supports C trigraphs.
+
+=item *
+
+L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
+newly created extensions that define constants. Since the new code is
+more correct (if you have two constants where the first one is a
+prefix of the second one, the first constant B<never> gets defined),
+less lossy (it uses integers for integer constant, as opposed to the
+old code that used floating point numbers even for integer constants),
+and slightly faster, you might want to consider regenerating your
+extension code (the new scheme makes regenerating easy).
+L<h2xs> now also supports C trigraphs.
+
+=item *
+
+L<libnetcfg> has been added to configure the libnet.
+
+=item *
+
+perlbug is now much more robust. It also sends the bug report to
+perl.org, not perl.com.
+
+=item *
+
+perlcc has been rewritten and its user interface (that is,
+command line) is much more like that of the UNIX C compiler, cc.
+
+=item *
+
+perlivp is a new utility for doing Installation Verification
+Procedure after installing Perl.
+
+=item *
+
+pod2html now allows specifying a cache directory.
+
+=item *
+
+s2p has been completely rewritten in Perl. (It is in fact a full
+implementation of sed in Perl.)
+
+=item *
+
+xsubpp now understands POD documentation embedded in the *.xs files.
+
+=item *
+
+xsubpp now supports OUT keyword.
+
+=back
+
+=head1 New Documentation
+
+=over 4
+
+=item *
+
+perl56delta details the changes between the 5.005 release and the
+5.6.0 release.
+
+=item *
+
+perlclib documents the internal replacements for standard C library
+functions. (Interesting only for extension writers and Perl core
+hackers.)
+
+=item *
+
+perldebtut is a Perl debugging tutorial.
+
+=item *
+
+perlebcdic contains considerations for running Perl on EBCDIC platforms.
+Note that unfortunately EBCDIC platforms that used to supported back in
+Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
+bring them back to the fold.
+
+=item *
+
+perlintro is a gentle introduction to Perl.
+
+=item *
+
+perliol documents the internals of PerlIO with layers.
+
+=item *
+
+perlmodstyle is a style guide for writing modules.
+
+=item *
+
+perlnewmod tells about writing and submitting a new module.
+
+=item *
+
+perlpod has been rewritten to be clearer and to record the best
+practices gathered over the years.
+
+=item *
+
+perlpodstyle is a more formal specification of the pod format,
+mainly of interest for writers of pod applications, not to
+people writing in pod.
+
+=item *
+
+perlposix-bc explains using Perl on the POSIX-BC platform
+(an EBCDIC mainframe platform).
+
+=item *
+
+perlretut is a regular expression tutorial.
+
+=item *
+
+perlrequick is a regular expressions quick-start guide.
+Yes, much quicker than perlretut.
+
+=item *
+
+perltodo has been updated.
+
+=item *
+
+perltootc has been renamed as perltooc (to not to conflict
+with perltoot in filesystems restricted to "8.3" names)
+
+=item *
+
+perluniintro is an introduction to using Unicode in Perl
+(perlunicode is more of a reference)
+
+=item *
+
+perlutil explains the command line utilities packaged with the Perl
+distribution.
+
+=back
+
+The following platform-specific documents are available before
+the installation as README.I<platform>, and after the installation
+as perlI<platform>:
+
+ perlaix perlamiga perlapollo perlbeos perlbs2000
+ perlce perlcygwin perldgux perldos perlepoc perlhpux
+ perlhurd perlmachten perlmacos perlmint perlmpeix
+ perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
+ perltru64 perluts perlvmesa perlvms perlvos perlwin32
+
+=over 4
+
+=item *
+
+The documentation for the POSIX-BC platform is called "BS2000", to avoid
+confusion with the Perl POSIX module.
+
+=item *
+
+The documentation for the WinCE platform is called "CE", to avoid
+confusion with the perlwin32 documentation on 8.3-restricted filesystems.
+
+=back
+
+=head1 Performance Enhancements
+
+=over 4
+
+=item *
+
+map() that changes the size of the list should now work faster.
+
+=item *
+
+sort() has been changed to use mergesort internally as opposed to the
+earlier quicksort. For very small lists this may result in slightly
+slower sorting times, but in general the speedup should be at least
+20%. Additional bonuses are that the worst case behaviour of sort()
+is now better (in computer science terms it now runs in time O(N log N),
+as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
+and that sort() is now stable (meaning that elements with identical
+keys will stay ordered as they were before the sort).
+
+=item *
+
+Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
+(http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
+reasonably fast while producing a much better spread of values than
+the old hashing algorithm (originally by Chris Torek, later tweaked by
+Ilya Zakharevich). Hash values output from the algorithm on a hash of
+all 3-char printable ASCII keys comes much closer to passing the
+DIEHARD random number generation tests. According to perlbench, this
+change has not affected the overall speed of Perl.
+
+=item *
+
+unshift() should now be noticeably faster.
+
+=back
+
+=head1 Installation and Configuration Improvements
+
+=head2 Generic Improvements
+
+=over 4
+
+=item *
+
+INSTALL now explains how you can configure Perl to use 64-bit
+integers even on non-64-bit platforms.
+
+=item *
+
+Policy.sh policy change: if you are reusing a Policy.sh file
+(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
+Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
+them will now be changed to the new prefix, /foo/bar. (Previously
+only $prefix changed.) If you do not like this new behaviour,
+specify prefix, siteprefix, and vendorprefix explicitly.
+
+=item *
+
+A new optional location for Perl libraries, otherlibdirs, is available.
+It can be used for example for vendor add-ons without disturbing Perl's
+own library directories.
+
+=item *
+
+In many platforms the vendor-supplied 'cc' is too stripped-down to
+build Perl (basically, 'cc' doesn't do ANSI C). If this seems
+to be the case and 'cc' does not seem to be the GNU C compiler
+'gcc', an automatic attempt is made to find and use 'gcc' instead.
+
+=item *
+
+gcc needs to closely track the operating system release to avoid
+build problems. If Configure finds that gcc was built for a different
+operating system release than is running, it now gives a clearly visible
+warning that there may be trouble ahead.
+
+=item *
+
+If binary compatibility with the 5.005 release is not wanted, Configure
+no longer suggests including the 5.005 modules in @INC.
+
+=item *
+
+Configure C<-S> can now run non-interactively.
+
+=item *
+
+configure.gnu now works with options with whitespace in them.
+
+=item *
+
+installperl now outputs everything to STDERR.
+
+=item *
+
+$Config{byteorder} is now computed dynamically (this is more robust
+with "fat binaries" where an executable image contains binaries for
+more than one binary platform.)
+
+=item *
+
+Because PerlIO is now the default on most platforms, "-perlio" doesn't
+get appended to the $Config{archname} (also known as $^O) anymore.
+Instead, if you explicitly choose not to use perlio (Configure command
+line option -Uuseperlio), you will get "-stdio" appended.
+
+=item *
+
+Another change related to the architecture name is that "-64all"
+(-Duse64bitall, or "maximally 64-bit") is appended only if your
+pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
+
+=item *
+
+In AFS installations one can configure the root of the AFS to be
+somewhere else than the default F</afs> by using the Configure
+parameter C<-Dafsroot=/some/where/else>.
+
+=item *
+
+APPLLIB_EXP, a less-know configuration-time definition, has been
+documented. It can be used to prepend site-specific directories
+to Perl's default search path (@INC), see INSTALL for information.
+
+=item *
+
+The version of Berkeley DB used when the Perl (and, presumably, the
+DB_File extension) was built is now available as
+C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
+from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
+DB_VERSION_PATCH_CFG> from C.
+
+=item *
+
+Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
+has been documented in INSTALL.
+
+=item *
+
+If you have CPAN access (either network or a local copy such as a
+CD-ROM) you can during specify extra modules to Configure to build and
+install with Perl using the -Dextras=... option. See INSTALL for
+more details.
+
+=item *
+
+In addition to config.over a new override file, config.arch, is
+available. That is supposed to be used by hints file writers for
+architecture-wide changes (as opposed to config.over which is for
+site-wide changes).
+
+=item *
+
+For Perl developers several new make targets for profiling
+and debugging have been added, see L<perlhack>.
+
+=over 8
+
+=item *
+
+Use of the F<gprof> tool to profile Perl has been documented in
+L<perlhack>. There is a make target called "perl.gprof" for
+generating a gprofiled Perl executable.
+
+=item *
+
+If you have GCC 3, there is a make target called "perl.gcov" for
+creating a gcoved Perl executable for coverage analysis. See
+L<perlhack>.
+
+=item *
+
+If you are on IRIX or Tru64 platforms, new profiling/debugging options
+have been added, see L<perlhack> for more information about pixie and
+Third Degree.
+
+=back
+
+=item *
+
+Guidelines of how to construct minimal Perl installations have
+been added to INSTALL.
+
+=item *
+
+The Thread extension is now not built at all under ithreads
+(C<Configure -Duseithreads>) because it wouldn't work anyway (the
+Thread extension requires being Configured with C<-Duse5005threads>).
+
+But note that the Thread.pm interface is now shared by both
+thread models.
+
+=back
+
+=head2 New Or Improved Platforms
+
+For the list of platforms known to support Perl,
+see L<perlport/"Supported Platforms">.
+
+=over 4
+
+=item *
+
+AIX dynamic loading should be now better supported.
+
+=item *
+
+AIX should now work better with gcc, threads, and 64-bitness. Also the
+long doubles support in AIX should be better now. See L<perlaix>.
+
+=item *
+
+After a long pause, AmigaOS has been verified to be happy with Perl.
+
+=item *
+
+AtheOS (http://www.atheos.cx/) is a new platform.
+
+=item *
+
+DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
+
+=item *
+
+DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
+
+=item *
+
+EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
+have been regained. Many test suite tests still fail and the
+co-existence of Unicode and EBCDIC isn't quite settled, but the
+situation is much better than with Perl 5.6. See L<perlos390>,
+L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
+
+=item *
+
+Building perl with -Duseithreads or -Duse5005threads now works under
+HP-UX 10.20 (previously it only worked under 10.30 or later). You will
+need a thread library package installed. See README.hpux.
+
+=item *
+
+MacOS Classic (MacPerl has of course been available since
+perl 5.004 but now the source code bases of standard Perl
+and MacPerl have been synchronised)
=item *
-In many platforms the vendor-supplied 'cc' is too stripped-down to
-build Perl (basically, 'cc' doesn't do ANSI C). If this seems
-to be the case and 'cc' does not seem to be the GNU C compiler
-'gcc', an automatic attempt is made to find and use 'gcc' instead.
+MacOS X (or Darwin) should now be able to build Perl even on HFS+
+filesystems. (The case-insensitivity confused the Perl build process.)
=item *
-gcc needs to closely track the operating system release to avoid
-build problems. If Configure finds that gcc was built for a different
-operating system release than is running, it now gives a clearly visible
-warning that there may be trouble ahead.
+NCR MP-RAS is now supported.
=item *
-If binary compatibility with the 5.005 release is not wanted, Configure
-no longer suggests including the 5.005 modules in @INC.
+NetWare from Novell is now supported. See L<perlnetware>.
=item *
-Configure C<-S> can now run non-interactively.
+NonStop-UX is now supported.
=item *
-configure.gnu now works with options with whitespace in them.
+Amdahl UTS UNIX mainframe platform is now supported.
=item *
-installperl now outputs everything to STDERR.
+WinCE is now supported. See L<perlce>.
=item *
-$Config{byteorder} is now computed dynamically (this is more robust
-with "fat binaries" where an executable image contains binaries for
-more than one binary platform.)
+z/OS (formerly known as OS/390, formerly known as MVS OE) has now
+support for dynamic loading. This is not selected by default,
+however, you must specify -Dusedl in the arguments of Configure.
=back
=head1 Selected Bug Fixes
+Numerous memory leaks and uninitialized memory accesses have been hunted down.
+Most importantly anonymous subs used to leak quite a bit.
+
=over 4
=item *
scalar() now forces scalar context even when used in void context.
=item *
-
+
sort() arguments are now compiled in the right wantarray context
(they were accidentally using the context of the sort() itself).
BOMs (byte order marks) in the beginning of Perl files
(scripts, modules) should now be transparently skipped.
-UTF16 encoded Perl files should now be read correctly.
+UTF-16 (UCS-2) encoded Perl files should now be read correctly.
=item *
-The character tables have been updated to new Unicode 3.0 features.
+The character tables have been updated to Unicode 3.0.1.
=item *
=item *
+vec() now refuses to deal with characters >255.
+
+=item *
+
Zero entries were missing from the Unicode classes like C<IsDigit>.
+=item *
+
+chop(@list) in list context returned the characters chopped in
+reverse order. This has been reversed to be in the right order.
+
+=item *
+
+The order of DESTROYs has been made more predictable.
+
+=item *
+
+mkdir() now ignores trailing slashes in the directory name,
+as mandated by POSIX.
+
+=item *
+
+Attributes (like :shared) didn't work with our().
+
+=item *
+
+The PERL5OPT environment variable (for passing command line arguments
+to Perl) didn't work for more than a single group of options.
+
+=item *
+
+The tainting behaviour of sprintf() has been rationalized. It does
+not taint the result of floating point formats anymore, making the
+behaviour consistent with that of string interpolation.
+
+=item *
+
+All but the first argument of the IO syswrite() method are now optional.
+
+=item *
+
+Tie::ARRAY SPLICE method was broken.
+
+=item *
+
+vec() now tries to work with characters <= 255 when possible, but it leaves
+higher character values in place. In that case, if vec() was used to modify
+the string, it is no longer considered to be utf8-encoded.
+
+=item *
+
+The autouse pragma didn't work for Multi::Part::Function::Names.
+
+=item *
+
+The behaviour of non-decimal but numeric string constants such as
+"0x23" was platform-dependent: in some platforms that was seen as 35,
+in some as 0, in some as a floating point number (don't ask). This
+was caused by Perl using the operating system libraries in a situation
+where the result of the string to number conversion is undefined: now
+Perl consistently handles such strings as zero in numeric contexts.
+
+=item *
+
+L<dprofpp> -R didn't work.
+
+=item *
+
+PERL5OPT with embedded spaces didn't work.
+
+=item *
+
+L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
+
+=item *
+
+Some versions of glibc have a broken modfl(). This affects builds
+with C<-Duselongdouble>. This version of Perl detects this brokenness
+and has a workaround for it. The glibc release 2.2.2 is known to have
+fixed the modfl() bug.
+
+=item *
+
+Linux previously had problems related to sockaddrlen when using
+accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
+
+=item *
+
+Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
+
+=item *
+
+Windows
+
+=over 8
+
+=item *
+
+Borland C++ v5.5 is now a supported compiler that can build Perl.
+However, the generated binaries continue to be incompatible with those
+generated by the other supported compilers (GCC and Visual C++).
+
+=item *
+
+Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
+Other bugs in chdir() and Cwd::cwd() have also been fixed.
+
+=item *
+
+Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
+
+=item *
+
+HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
+
+=item *
+
+The makefiles now provide a single switch to bulk-enable all the features
+enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
+
+=back
+
=back
=item *
UNIVERSAL::isa no longer caches methods incorrectly. (This broke
the Tk extension with 5.6.0.)
+=item *
+
+Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
+when building the Perl binary. The only exception to this is SunOS 4.x,
+which needs them.
+
+=item *
+
+SOCKS support is now much more robust.
+
+=item *
+
+If your file system supports symbolic links you can build Perl outside
+of the source directory by
+
+ mkdir /tmp/perl/build/directory
+ cd /tmp/perl/build/directory
+ sh /path/to/perl/source/Configure -Dmksymlinks ...
+
+This will create in /tmp/perl/build/directory a tree of symbolic links
+pointing to files in /path/to/perl/source. The original files are left
+unaffected. After Configure has finished you can just say
+
+ make all test
+
+and Perl will be built and tested, all in /tmp/perl/build/directory.
+
=back
=head2 Platform Specific Changes and Fixes
=item *
Less stack reserved per thread so that more threads can run
-concurrently. (still 16M perl thread)
+concurrently. (Still 16M per thread.)
=item *
C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
-(works better when perl running as service).
+(works better when perl is running as service).
=item *
=back
+=back
+
=head1 New or Changed Diagnostics
+=over 4
+
+=item *
+
All regular expression compilation error messages are now hopefully
easier to understand both because the error message now comes before
the failed regex and because the point of failure is now clearly
-marked.
+marked by a C<E<lt>-- HERE> marker.
+
+=item *
The various "opened only for", "on closed", "never opened" warnings
drop the C<main::> prefix for filehandles in the C<main> package,
for example C<STDIN> instead of <main::STDIN>.
+=item *
+
The "Unrecognized escape" warning has been extended to include C<\8>,
C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
+=item *
+
+Two new debugging options have been added: if you have compiled your
+Perl with debugging, you can use the -DT and -DR options to trace
+tokenising and to add reference counts to displaying variables,
+respectively.
+
+=item *
+
+If an attempt to use a (non-blessed) reference as an array index
+is made, a warning is given.
+
+=item *
+
+C<push @a;> and C<unshift @a;> (with no values to push or unshift)
+now give a warning. This may be a problem for generated and evaled
+code.
+
+=item *
+
+If you try to L<perlfunc/pack> a number less than 0 or larger than 255
+using the C<"C"> format you will get an optional warning. Similarly
+for the C<"c"> format and a number less than -128 or more than 127.
+
+=item *
+
+Certain regex modifiers such as C<(?o)> make sense only if applied to
+the entire regex. You will an optional warning if you try to do otherwise.
+
+=item *
+
+Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
+deprecated for a while. Now you will get an optional warning.
+
+=back
+
=head1 Changed Internals
=over 4
Building microperl does not require even running Configure;
C<make -f Makefile.micro> should be enough. Beware: microperl makes
many assumptions, some of which may be too bold; the resulting
-executable may crash or otherwise misbehave in wondrous ways. For
-careful hackers only.
+executable may crash or otherwise misbehave in wondrous ways.
+For careful hackers only.
=item *
Now xsubs can have attributes just like subs.
-=back
+=item *
-=head1 Known Problems
+Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
+For the full list of the available APIs see L<perlapi>.
+
+=item *
-=head2 Unicode Support Still Far From Perfect
+dTHR and djSP have been obsoleted; the former removed (because it's
+a no-op) and the latter replaced with dSP.
-We're working on it. Stay tuned.
+=item *
-=head2 EBCDIC Still A Lost Platform
+PERL_OBJECT has been completely removed.
-The plan is to bring them back.
+=item *
-=head2 Building Extensions Can Fail Because Of Largefiles
+The MAGIC constants (e.g. C<'P'>) have been macrofied
+(e.g. C<PERL_MAGIC_TIED>) for better source code readability
+and maintainability.
-Certain extensions like mod_perl and BSD::Resource are known to have
-issues with `largefiles', a change brought by Perl 5.6.0 in which file
-offsets default to 64 bits wide, where supported. Modules may fail to
-compile at all or compile and work incorrectly. Currently there is no
-good solution for the problem, but Configure now provides appropriate
-non-largefile ccflags, ldflags, libswanted, and libs in the %Config
-hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
-having problems can try configuring themselves without the
-largefileness. This is admittedly not a clean solution, and the
-solution may not even work at all. One potential failure is whether
-one can (or, if one can, whether it's a good idea) link together at
-all binaries with different ideas about file offsets, all this is
-platform-dependent.
+=item *
-=head2 ftmp-security tests warn 'system possibly insecure'
+The regex compiler now maintains a structure that identifies nodes in
+the compiled bytecode with the corresponding syntactic features of the
+original regex expression. The information is attached to the new
+C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
+complete information.
-Don't panic. Read INSTALL 'make test' section instead.
+=item *
-=head2 Long Doubles Still Don't Work In Solaris
+The C code has been made much more C<gcc -Wall> clean. Some warning
+messages still remain in some platforms, so if you are compiling with
+gcc you may see some warnings about dubious practices. The warnings
+are being worked on.
-The experimental long double support is still very much so in Solaris.
-(Other platforms like Linux and Tru64 are beginning to solidify in
-this area.)
+=item *
-=head2 Storable tests fail in some platforms
+F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
-If any Storable tests fail the use of Storable is not advisable.
+=item *
-=over 4
+Documentation on how to use the Perl source repository has been added
+to F<Porting/repository.pod>.
=item *
-Many Storable tests fail on AIX configured with 64 bit integers.
+There are now several profiling make targets
-So far unidentified problems break Storable in AIX if Perl is
-configured to use 64 bit integers. AIX in 32-bit mode works and
-other 64-bit platforms work with Storable.
+=item *
+
+The C<op_clear> and C<op_null> are now exported.
+
+=back
+
+=head1 Security Vulnerability Closed
+
+(This change was already made in 5.7.0 but bears repeating here.)
+
+A potential security vulnerability in the optional suidperl component
+of Perl was identified in August 2000. suidperl is neither built nor
+installed by default. As of November 2001 the only known vulnerable
+platform is Linux, most likely all Linux distributions. CERT and
+various vendors and distributors have been alerted about the vulnerability.
+See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
+for more information.
+
+The problem was caused by Perl trying to report a suspected security
+exploit attempt using an external program, /bin/mail. On Linux
+platforms the /bin/mail program had an undocumented feature which
+when combined with suidperl gave access to a root shell, resulting in
+a serious compromise instead of reporting the exploit attempt. If you
+don't have /bin/mail, or if you have 'safe setuid scripts', or if
+suidperl is not installed, you are safe.
+
+The exploit attempt reporting feature has been completely removed from
+Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
+from all the Perl 5.7 releases), so that particular vulnerability
+isn't there anymore. However, further security vulnerabilities are,
+unfortunately, always possible. The suidperl functionality is most
+probably going to be removed in Perl 5.10. In any case, suidperl
+should only be used by security experts who know exactly what they are
+doing and why they are using suidperl instead of some other solution
+such as sudo (see http://www.courtesan.com/sudo/).
+
+=head1 New Tests
+
+Several new tests have been added, especially for the F<lib> subsection.
+
+The tests are now reported in a different order than in earlier Perls.
+(This happens because the test scripts from under t/lib have been moved
+to be closer to the library/extension they are testing.)
+
+=head1 Known Problems
+
+Note that unlike other sections in this document (which describe
+changes since 5.7.0) this section is cumulative containing known
+problems for all the 5.7 releases.
+
+=head2 AIX
+
+=over 4
=item *
-DOS DJGPP may hang when testing Storable.
+In AIX 4.2 Perl extensions that use C++ functions that use statics
+may have problems in that the statics are not getting initialized.
+In newer AIX releases this has been solved by linking Perl with
+the libC_r library, but unfortunately in AIX 4.2 the said library
+has an obscure bug where the various functions related to time
+(such as time() and gettimeofday()) return broken values, and
+therefore in AIX 4.2 Perl is not linked against the libC_r.
+
+=item *
+
+vac 5.0.0.0 May Produce Buggy Code For Perl
+
+The AIX C compiler vac version 5.0.0.0 may produce buggy code,
+resulting in few random tests failing, but when the failing tests
+are run by hand, they succeed. We suggest upgrading to at least
+vac version 5.0.1.0, that has been known to compile Perl correctly.
+"lslpp -L|grep vac.C" will tell you the vac version.
+
+=back
+
+=head2 Amiga Perl Invoking Mystery
+
+One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
+works, but for example C<bin:perl -v> doesn't. The exact reason is
+known but the current suspect is the F<ixemul> library.
+
+=head2 lib/ftmp-security tests warn 'system possibly insecure'
+
+Don't panic. Read INSTALL 'make test' section instead.
+
+=head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
+
+The subtests 11 and 12 sometimes fail and sometimes work.
+
+=head2 HP-UX lib/io_multihomed Fails When LP64-Configured
+
+The lib/io_multihomed test may hang in HP-UX if Perl has been
+configured to be 64-bit. Because other 64-bit platforms do not hang in
+this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
+test attempts to create and connect to "multihomed" sockets (sockets
+which have multiple IP addresses).
+
+=head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
+
+If perl is configured with -Duse64bitall, the successful result of the
+subtest 10 of lib/posix may arrive before the successful result of the
+subtest 9, which confuses the test harness so much that it thinks the
+subtest 9 failed.
+
+=head2 Linux With Sfio Fails op/misc Test 48
+
+No known fix.
+
+=head2 OS/390
+
+OS/390 has rather many test failures but the situation is actually
+better than it was in 5.6.0, it's just that so many new modules and
+tests have been added.
+
+ Failed Test Stat Wstat Total Fail Failed List of Failed
+ -----------------------------------------------------------------------------
+ ../ext/B/Deparse.t 14 1 7.14% 14
+ ../ext/B/Showlex.t 1 1 100.00% 1
+ ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
+ 600 602 604-610
+ ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
+ ../ext/POSIX/POSIX.t 29 1 3.45% 14
+ ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
+ ../lib/locale.t 129 33024 117 19 16.24% 99-117
+ ../lib/warnings.t 434 1 0.23% 75
+ ../lib/ExtUtils.t 27 1 3.70% 25
+ ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
+ ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
+ ../lib/User/pwent.t 9 1 11.11% 4
+ op/pat.t 660 6 0.91% 242-243 424-425
+ 626-627
+ op/split.t 0 9 ?? ?? % ??
+ op/taint.t 174 3 1.72% 156 162 168
+ op/tr.t 70 3 4.29% 50 58-59
+ Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
+
+=head2 op/sprintf tests 129 and 130
+
+The op/sprintf tests 129 and 130 are known to fail on some platforms.
+Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
+The failing platforms do not comply with the ANSI C Standard, line
+19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
+something other than "1" and "-1" when formatting 0.6 and -0.6 using
+the printf format "%.0f", most often they produce "0" and "-0".)
+
+=head2 Failure of Thread tests
+
+B<Note that support for 5.005-style threading remains experimental.>
+
+The following tests are known to fail due to fundamental problems in
+the 5.005 threading implementation. These are not new failures--Perl
+5.005_0x has the same bugs, but didn't have these tests.
+
+ lib/autouse.t 4
+ t/lib/thr5005.t 19-20
+
+=head2 UNICOS
+
+=over 4
=item *
-st-06compat fails in UNICOS and UNICOS/mk.
+ext/POSIX/sigaction subtests 6 and 13 may fail.
+
+=item *
-This means that you cannot read old (pre-Storable-0.7) Storable images
-made in other platforms.
+lib/ExtUtils may spuriously claim that subtest 28 failed,
+which is interesting since the test only has 27 tests.
=item *
-st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
+Numerous numerical test failures
+
+ op/numconvert 209,210,217,218
+ op/override 7
+ ext/Time/HiRes/HiRes 9
+ lib/Math/BigInt/t/bigintpm 1145
+ lib/Math/Trig 25
+
+These tests fail because of yet unresolved floating point inaccuracies.
=back
+=head2 UTS
+
+There are a few known test failures, see L<perluts>.
+
+=head2 VMS
+
+Rather many tests are failing in VMS but that actually more tests
+succeed in VMS than they used to, it's just that there are many,
+many more tests than there used to be.
+
+Here are the known failures from some compiler/platform combinations.
+
+DEC C V5.3-006 on OpenVMS VAX V6.2
+
+ [-.ext.list.util.t]tainted..............FAILED on test 3
+ [-.ext.posix]sigaction..................FAILED on test 7
+ [-.ext.time.hires]hires.................FAILED on test 14
+ [-.lib.file.find]taint..................FAILED on test 17
+ [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
+ [-.lib.test.simple.t]exit...............FAILED on test 1
+ [.lib]vmsish............................FAILED on test 13
+ [.op]sprintf............................FAILED on test 12
+ Failed 8/399 tests, 91.23% okay.
+
+DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and
+Compaq C V6.2-008 on OpenVMS Alpha V7.1
+
+ [-.ext.list.util.t]tainted..............FAILED on test 3
+ [-.lib.file.find]taint..................FAILED on test 17
+ [-.lib.test.simple.t]exit...............FAILED on test 1
+ [.lib]vmsish............................FAILED on test 13
+ Failed 4/399 tests, 92.48% okay.
+
+Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
+
+ [-.ext.b]showlex........................FAILED on test 1
+ [-.ext.list.util.t]tainted..............FAILED on test 3
+ [-.lib.file.find]taint..................FAILED on test 17
+ [-.lib.test.simple.t]exit...............FAILED on test 1
+ [.lib]vmsish............................FAILED on test 13
+ [.op]misc...............................FAILED on test 49
+ Failed 6/401 tests, 92.77% okay.
+
+=head2 Win32
+
+In multi-CPU boxes there are some problems with the I/O buffering:
+some output may appear twice.
+
+=head2 Localising a Tied Variable Leaks Memory
+
+ use Tie::Hash;
+ tie my %tie_hash => 'Tie::StdHash';
+
+ ...
+
+ local($tie_hash{Foo}) = 1; # leaks
+
+Code like the above is known to leak memory every time the local()
+is executed.
+
+=head2 Self-tying of Arrays and Hashes Is Forbidden
+
+Self-tying of arrays and hashes is broken in rather deep and
+hard-to-fix ways. As a stop-gap measure to avoid people from getting
+frustrated at the mysterious results (core dumps, most often) it is
+for now forbidden (you will get a fatal error even from an attempt).
+
+=head2 Variable Attributes are not Currently Usable for Tieing
+
+This limitation will hopefully be fixed in future. (Subroutine
+attributes work fine for tieing, see L<Attribute::Handlers>).
+
+=head2 Building Extensions Can Fail Because Of Largefiles
+
+Some extensions like mod_perl are known to have issues with
+`largefiles', a change brought by Perl 5.6.0 in which file offsets
+default to 64 bits wide, where supported. Modules may fail to compile
+at all or compile and work incorrectly. Currently there is no good
+solution for the problem, but Configure now provides appropriate
+non-largefile ccflags, ldflags, libswanted, and libs in the %Config
+hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
+having problems can try configuring themselves without the
+largefileness. This is admittedly not a clean solution, and the
+solution may not even work at all. One potential failure is whether
+one can (or, if one can, whether it's a good idea) link together at
+all binaries with different ideas about file offsets, all this is
+platform-dependent.
+
+=head2 The Compiler Suite Is Still Experimental
+
+The compiler suite is slowly getting better but is nowhere near
+working order yet.
+
+=head2 The Long Double Support is Still Experimental
+
+The ability to configure Perl's numbers to use "long doubles",
+floating point numbers of hopefully better accuracy, is still
+experimental. The implementations of long doubles are not yet
+widespread and the existing implementations are not quite mature
+or standardised, therefore trying to support them is a rare
+and moving target. The gain of more precision may also be offset
+by slowdown in computations (more bits to move around, and the
+operations are more likely to be executed by less optimised
+libraries).
+
=head1 Reporting Bugs
If you find what you think is a bug, you might check the articles
=head1 HISTORY
-Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
-from The Perl Porters and Perl Users submitting feedback and patches.
-
-Send omissions or corrections to <F<perlbug@perl.org>>.
+Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.
=cut
https://perl5.git.perl.org / perl5.git / blobdiff