3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release and the
16 Better Unicode support
20 New Thread Implementation
28 Better Numeric Accuracy
36 More Extensive Regression Testing
40 =head1 Incompatible Changes
42 =head2 64-bit platforms and malloc
44 If your pointers are 64 bits wide, the Perl malloc is no longer being
45 used because it does not work well with 8-byte pointers. Also,
46 usually the system mallocs on such platforms are much better optimized
47 for such large memory models than the Perl malloc. Some memory-hungry
48 Perl applications like the PDL don't work well with Perl's malloc.
49 Finally, other applications than Perl (like modperl) tend to prefer
50 the system malloc. Such platforms include Alpha and 64-bit HPPA,
53 =head2 AIX Dynaloading
55 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
56 dlopen interface of AIX instead of the old emulated interface. This
57 change will probably break backward compatibility with compiled
58 modules. The change was made to make Perl more compliant with other
59 applications like modperl which are using the AIX native interface.
61 =head2 Socket Extension Dynamic in VMS
63 The Socket extension is now dynamically loaded instead of being
64 statically built in. This may or may not be a problem with ancient
65 TCP/IP stacks of VMS: we do not know since we weren't able to test
66 Perl in such configurations.
68 =head2 Different Definition of the Unicode Character Classes \p{In...}
70 As suggested by the Unicode consortium, the Unicode character classes
71 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
72 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
73 constructs are used. This has changed the definition of some of those
76 The difference between scripts and blocks is that scripts are the
77 glyphs used by a language or a group of languages, while the blocks
78 are more artificial groupings of 256 characters based on the Unicode
81 In general this change results in more inclusive Unicode character
82 classes, but changes to the other direction also do take place:
83 for example while the script C<Latin> includes all the Latin
84 characters and their various diacritic-adorned versions, it
85 does not include the various punctuation or digits (since they
86 are not solely C<Latin>).
88 Changes in the character class semantics may have happened if a script
89 and a block happen to have the same name, for example C<Hebrew>.
90 In such cases the script wins and C<\p{InHebrew}> now means the script
91 definition of Hebrew. The block definition in still available,
92 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
93 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
94 of affected character classes, see L<perlunicode/Blocks>.
96 =head2 Perl Parser Stress Tested
98 The Perl parser has been stress tested using both random input and
99 Markov chain input and the few found crashes and lockups have been
102 =head2 REF(...) Instead Of SCALAR(...)
104 A reference to a reference now stringifies as "REF(0x81485ec)" instead
105 of "SCALAR(0x81485ec)" in order to be more consistent with the return
114 The semantics of bless(REF, REF) were unclear and until someone proves
115 it to make some sense, it is forbidden.
119 The obsolete chat2 library that should never have been allowed
120 to escape the laboratory has been decommissioned.
124 The very dusty examples in the eg/ directory have been removed.
125 Suggestions for new shiny examples welcome but the main issue is that
126 the examples need to be documented, tested and (most importantly)
131 The (bogus) escape sequences \8 and \9 now give an optional warning
132 ("Unrecognized escape passed through"). There is no need to \-escape
137 The list of filenames from glob() (or <...>) is now by default sorted
138 alphabetically to be csh-compliant. (bsd_glob() does still sort platform
139 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
143 Although "you shouldn't do that", it was possible to write code that
144 depends on Perl's hashed key order (Data::Dumper does this). The new
145 algorithm "One-at-a-Time" produces a different hashed key order.
146 More details are in L</"Performance Enhancements">.
150 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
151 In future releases this may become a fatal error.
155 The C<package;> syntax (C<package> without an argument) has been
156 deprecated. Its semantics were never that clear and its
157 implementation even less so. If you have used that feature to
158 disallow all but fully qualified variables, C<use strict;> instead.
162 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
163 recognised but now cause fatal errors. The previous behaviour of
164 ignoring them by default and warning if requested was unacceptable
165 since it, in a way, falsely promised that the features could be used.
169 The current user-visible implementation of pseudo-hashes (the weird
170 use of the first array element) is deprecated starting from Perl 5.8.0
171 and will be removed in Perl 5.10.0, and the feature will be
172 implemented differently. Not only is the current interface rather
173 ugly, but the current implementation slows down normal array and hash
174 use quite noticeably. The C<fields> pragma interface will remain
179 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
183 After years of trying the suidperl is considered to be too complex to
184 ever be considered truly secure. The suidperl functionality is likely
185 to be removed in a future release.
189 The long deprecated uppercase aliases for the string comparison
190 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
194 The tr///C and tr///U features have been removed and will not return;
195 the interface was a mistake. Sorry about that. For similar
196 functionality, see pack('U0', ...) and pack('C0', ...).
200 =head1 Core Enhancements
202 =head2 PerlIO is Now The Default
208 IO is now by default done via PerlIO rather than system's "stdio".
209 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
210 handle's behaviour. Layers can be specified at open time via 3-arg
213 open($fh,'>:crlf :utf8', $path) || ...
215 or on already opened handles via extended C<binmode>:
217 binmode($fh,':encoding(iso-8859-7)');
219 The built-in layers are: unix (low level read/write), stdio (as in
220 previous Perls), perlio (re-implementation of stdio buffering in a
221 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
222 but available on any platform). A mmap layer may be available if
223 platform supports it (mostly UNIXes).
225 Layers to be applied by default may be specified via the 'open' pragma.
227 See L</"Installation and Configuration Improvements"> for the effects
228 of PerlIO on your architecture name.
232 File handles can be marked as accepting Perl's internal encoding of Unicode
233 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
235 open($fh,">:utf8","Uni.txt");
237 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
238 for you since it's not UTF-8 what you will be getting but instead
239 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
240 http://www.unicode.org/unicode/reports/tr16/ for more information.
241 In future releases this naming may change.
245 File handles can translate character encodings from/to Perl's internal
246 Unicode form on read/write via the ":encoding()" layer.
250 File handles can be opened to "in memory" files held in Perl scalars via:
252 open($fh,'>', \$variable) || ...
256 Anonymous temporary files are available without need to
257 'use FileHandle' or other module via
259 open($fh,"+>", undef) || ...
261 That is a literal undef, not an undefined value.
265 The list form of C<open> is now implemented for pipes (at least on UNIX):
267 open($fh,"-|", 'cat', '/etc/motd')
269 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
274 =head2 Signals Are Now Safe
276 Perl used to be fragile in that signals arriving at inopportune moments
277 could corrupt Perl's internal state. Now Perl postpones handling of
278 signals until it's safe.
280 =head2 Unicode Overhaul
282 Unicode in general should be now much more usable than in Perl 5.6.0
283 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
284 regular expressions should work now, Unicode in tr/// should work now,
285 Unicode in I/O should work now.
291 The Unicode Character Database coming with Perl has been upgraded
292 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
296 For developers interested in enhancing Perl's Unicode capabilities:
297 almost all the UCD files are included with the Perl distribution in
298 the lib/unicore subdirectory. The most notable omission, for space
299 considerations, is the Unihan database.
303 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
304 added. "Blank" is like C isblank(), that is, it contains only
305 "horizontal whitespace" (the space character is, the newline isn't),
306 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
307 isn't, since that includes the vertical tabulator character, whereas
312 =head2 Understanding of Numbers
314 In general a lot of fixing has happened in the area of Perl's
315 understanding of numbers, both integer and floating point. Since in
316 many systems the standard number parsing functions like C<strtoul()>
317 and C<atof()> seem to have bugs, Perl tries to work around their
318 deficiencies. This results hopefully in more accurate numbers.
320 Perl now tries internally to use integer values in numeric conversions
321 and basic arithmetics (+ - * /) if the arguments are integers, and
322 tries also to keep the results stored internally as integers.
323 This change leads to often slightly faster and always less lossy
324 arithmetics. (Previously Perl always preferred floating point numbers
327 =head2 Miscellaneous Enhancements
333 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
334 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
338 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
339 in multiple arguments.)
343 END blocks are now run even if you exit/die in a BEGIN block.
344 Internally, the execution of END blocks is now controlled by
345 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
346 behaviour for Perl embedders. This will default in 5.10. See
351 Formats now support zero-padded decimal fields.
355 Lvalue subroutines can now return C<undef> in list context.
359 A new special regular expression variable has been introduced:
360 C<$^N>, which contains the most-recently closed group (submatch).
364 C<no Module;> now works even if there is no "sub unimport" in the Module.
368 The numerical comparison operators return C<undef> if either operand
369 is a NaN. Previously the behaviour was unspecified.
373 The following builtin functions are now overridable: each(), keys(),
374 pop(), push(), shift(), splice(), unshift().
378 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
382 my __PACKAGE__ $obj now works.
386 The printf() and sprintf() now support parameter reordering using the
387 C<%\d+\$> and C<*\d+\$> syntaxes. For example
389 print "%2\$s %1\$s\n", "foo", "bar";
391 will print "bar foo\n". This feature helps in writing
392 internationalised software, and in general when the order
393 of the parameters can vary.
397 prototype(\&) is now available.
401 prototype(\[$@%&]) is now available to implicitly create references
402 (useful for example if you want to emulate the tie() interface).
406 UNTIE method is now recognised.
410 L<utime> now supports C<utime undef, undef, @files> to change the
411 file timestamps to the current time.
415 The rules for allowing underscores (underbars) in numeric constants
416 have been relaxed and simplified: now you can have an underscore
417 simply B<between digits>.
421 =head1 Modules and Pragmata
423 =head2 New Modules and Pragmata
429 C<Attribute::Handlers> allows a class to define attribute handlers.
432 use Attribute::Handlers;
433 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
435 # later, in some package using or inheriting from MyPack...
437 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
439 Both variables and routines can have attribute handlers. Handlers can
440 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
441 exact compilation phase (BEGIN, CHECK, INIT, or END).
445 B<B::Concise> is a new compiler backend for walking the Perl syntax
446 tree, printing concise info about ops, from Stephen McCamant. The
447 output is highly customisable. See L<B::Concise>.
451 C<Class::ISA> for reporting the search path for a class's ISA tree,
452 by Sean Burke, has been added. See L<Class::ISA>.
456 C<Cwd> has now a split personality: if possible, an XS extension is
457 used, (this will hopefully be faster, more secure, and more robust)
458 but if not possible, the familiar Perl implementation is used.
462 C<Devel::PPPort>, originally from Kenneth Albanowski and now
463 maintained by Paul Marquess, has been added. It is primarily used
464 by C<h2xs> to enhance portability of of XS modules between different
469 C<Digest>, frontend module for calculating digests (checksums), from
470 Gisle Aas, has been added. See L<Digest>.
474 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
475 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
477 use Digest::MD5 'md5_hex';
479 $digest = md5_hex("Thirsty Camel");
481 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
483 NOTE: the C<MD5> backward compatibility module is deliberately not
484 included since its further use is discouraged.
488 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
489 between different character encodings. Support for Unicode,
490 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
491 compiled in to the module. Several other encodings (like Japanese,
492 Chinese, and MacIntosh encodings) are included and will be loaded at
493 runtime. See L<Encode>.
495 Any encoding supported by Encode module is also available to the
496 ":encoding()" layer if PerlIO is used.
500 C<I18N::Langinfo> can be use to query locale information.
501 See L<I18N::Langinfo>.
505 C<I18N::LangTags> has functions for dealing with RFC3066-style
506 language tags, by Sean Burke. See L<I18N::LangTags>.
510 C<ExtUtils::Constant> is a new tool for extension writers for
511 generating XS code to import C header constants, by Nicholas Clark.
512 See L<ExtUtils::Constant>.
516 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
517 from Damian Conway. See L<Filter::Simple>.
523 use Filter::Simple sub {
524 while (my ($from, $to) = splice @_, 0, 2) {
533 use MyFilter qr/red/ => 'green';
535 print "red\n"; # this code is filtered, will print "green\n"
536 print "bored\n"; # this code is filtered, will print "bogreen\n"
540 print "red\n"; # this code is not filtered, will print "red\n"
544 C<File::Temp> allows one to create temporary files and directories in
545 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
549 C<Filter::Util::Call> provides you with the framework to write
550 I<Source Filters> in Perl, from Paul Marquess. For most uses the
551 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
555 L<libnet> is a collection of perl5 modules related to network
556 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
557 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
559 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
563 C<List::Util> is a selection of general-utility list subroutines, like
564 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
568 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
569 C<Locale::Language>, from Neil Bowers, have been added. They provide the
570 codes for various locale standards, such as "fr" for France, "usd" for
571 US Dollar, and "jp" for Japanese.
575 $country = code2country('jp'); # $country gets 'Japan'
576 $code = country2code('Norway'); # $code gets 'no'
578 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
579 and L<Locale::Language>.
583 C<Locale::Maketext> is localization framework from Sean Burke. See
584 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
585 article about software localization, originally published in The Perl
586 Journal #13, republished here with kind permission.
590 C<Memoize> can make your functions faster by trading space for time,
591 from Mark-Jason Dominus. See L<Memoize>.
595 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
596 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
601 $encoded = encode_base64('Aladdin:open sesame');
602 $decoded = decode_base64($encoded);
604 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
610 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
611 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
612 Extensions)>, from Gisle Aas.
614 use MIME::QuotedPrint;
616 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
617 $decoded = decode_qp($encoded);
619 print $encoded, "\n"; # "Smiley in Unicode: =263A"
621 MIME::QuotedPrint has been enhanced to provide the basic methods
622 necessary to use it with PerlIO::Via as in :
624 use MIME::QuotedPrint;
625 open($fh,">Via(MIME::QuotedPrint)",$path);
627 See L<MIME::QuotedPrint>.
631 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
636 C<open> is a new pragma for setting the default I/O disciplines
641 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
642 Perl scalars as discussed above, from Nick Ing-Simmons. It also
643 serves as an example of a loadable PerlIO layer. Other future
644 possibilities include PerlIO::Array and PerlIO::Code.
645 See L<PerlIO::Scalar>.
649 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
650 functionality provided by a class (typically implemented in perl
651 code), from Nick Ing-Simmons.
653 use MIME::QuotedPrint;
654 open($fh,">Via(MIME::QuotedPrint)",$path);
656 This will automatically convert everything output to C<$fh>
657 to Quoted-Printable. See L<PerlIO::Via>.
661 C<Pod::ParseLink>, by Russ Allbery, has been added,
662 to parse L<> links in pods as described in the new
667 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
668 It converts POD data to formatted overstrike text.
669 See L<Pod::Text::Overstrike>.
673 C<Scalar::Util> is a selection of general-utility scalar subroutines,
674 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
678 C<sort> is a new pragma for controlling the behaviour of sort().
682 C<Storable> gives persistence to Perl data structures by allowing the
683 storage and retrieval of Perl data to and from files in a fast and
684 compact binary format, from Raphael Manfredi. See L<Storable>.
688 C<Switch>, from Damian Conway, has been added. Just by saying
692 you have C<switch> and C<case> available in Perl.
698 case 1 { print "number 1" }
699 case "a" { print "string a" }
700 case [1..10,42] { print "number in list" }
701 case (@array) { print "number in list" }
702 case /\w+/ { print "pattern" }
703 case qr/\w+/ { print "pattern" }
704 case (%hash) { print "entry in hash" }
705 case (\%hash) { print "entry in hash" }
706 case (\&sub) { print "arg to subroutine" }
707 else { print "previous case not true" }
714 C<Test::More> is yet another framework for writing test scripts,
715 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
719 C<Test::Simple> has basic utilities for writing tests, by Michael
720 Schwern. See L<Test::Simple>.
724 C<Text::Balanced> has been added, for extracting delimited text
725 sequences from strings, from Damian Conway.
727 use Text::Balanced 'extract_delimited';
729 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
731 $a will be "'never say never'", $b will be ', he never said'.
733 In addition to extract_delimited() there are also extract_bracketed(),
734 extract_quotelike(), extract_codeblock(), extract_variable(),
735 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
736 gen_extract_tagged(). With these you can implement rather advanced
737 parsing algorithms. See L<Text::Balanced>.
741 C<threads> is an interface to interpreter threads, by Arthur Bergman.
742 Interpreter threads (ithreads) is the new thread model introduced in
743 Perl 5.6 but only available as an internal interface for extension
744 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
748 C<threads::shared> allows data sharing for interpreter threads, from
749 Arthur Bergman. In the ithreads model any data sharing between
750 threads must be explicit, as opposed to the old 5.005 thread model
751 where data sharing was implicit. See L<threads::shared>.
755 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
756 references (unlike the standard Tie::RefHash) The module is contained
757 within Tie::RefHash, see L<Tie::RefHash>.
761 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
762 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
766 C<Unicode::UCD> offers a querying interface to the Unicode Character
767 Database. See L<Unicode::UCD>.
771 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
772 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
776 C<Unicode::Normalize> implements the various Unicode normalization
777 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
781 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
782 typemaps. Nothing gets installed but for extension writers the code
787 =head2 Updated And Improved Modules and Pragmata
793 The following independently supported modules have been updated to the
794 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
795 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
796 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
797 Term::ANSIColor, Test, Text-Tabs+Wrap.
801 The attributes::reftype() now works on tied arguments.
805 AutoLoader can now be disabled with C<no AutoLoader;>.
809 B::Deparse has been significantly enhanced. It now can deparse almost
810 all of the standard test suite (so that the tests still succeed).
811 There is a make target "test.deparse" for trying this out.
815 Class::Struct can now define the classes in compile time.
819 Class::Struct now assigns the array/hash element if the accessor
820 is called with an array/hash element as the B<sole> argument.
824 Data::Dumper has now an option to sort hashes.
828 Data::Dumper has now an option to dump code references
833 The English module can now be used without the infamous performance
836 use English '-no_performance_hit';
838 (Assuming, of course, that one doesn't need the troublesome variables
839 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
840 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
844 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
845 new-style constant dispatch section (see L<ExtUtils::Constant>).
846 This means that they will be more robust and hopefully faster.
850 File::Find now has pre- and post-processing callbacks. It also
851 correctly changes directories when chasing symbolic links. Callbacks
852 (naughtily) exiting with "next;" instead of "return;" now work.
856 File::Find is now (again) reentrant. It also has been made
861 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
862 prototype mismatch with CORE::glob().
866 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
867 the returned list of filenames.
871 Devel::Peek now has an interface for the Perl memory statistics
872 (this works only if you are using perl's malloc, and if you have
873 compiled with debugging).
877 IPC::Open3 now allows the use of numeric file descriptors.
881 IO::Socket has now atmark() method, which returns true if the socket
882 is positioned at the out-of-band mark. The method is also exportable
883 as a sockatmark() function.
887 IO::Socket::INET has support for ReusePort option (if your platform
888 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
889 you may want to prefer ReuseAddr.
893 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
894 that the operating system will make one up.)
898 use lib now works identically to @INC. Removing directories
899 with 'no lib' now works.
903 Math::BigFloat and Math::BigInt have undergone a full rewrite.
904 They are now magnitudes faster, and they support various
905 bignum libraries such as GMP and PARI as their backends.
909 Net::Ping has been enhanced. There is now "external" protocol which
910 uses Net::Ping::External module which runs external ping(1) and parses
911 the output. An alpha version of Net::Ping::External is available in
912 CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
916 POSIX::sigaction() is now much more flexible and robust.
917 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
918 handlers, installing new handlers was not atomic.
922 In Safe the C<%INC> now localised in a Safe compartment so that
927 In Search::Dict one can now have a pre-processing hook for the
928 lines being searched.
932 The Shell module now has an OO interface.
936 The Test module has been significantly enhanced.
940 The vars pragma now supports declaring fully qualified variables.
941 (Something that C<our()> does not and will not support.)
945 The utf8:: name space (as in the pragma) provides various
946 Perl-callable functions to provide low level access to Perl's
947 internal Unicode representation. At the moment only length()
948 has been implemented.
952 =head1 Utility Changes
958 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
963 F<emacs/e2ctags.pl> is now much faster.
967 C<h2ph> now supports C trigraphs.
971 C<h2xs> now produces a template README.
975 C<h2xs> now uses C<Devel::PPort> for better portability between
976 different versions of Perl.
980 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
981 newly created extensions that define constants. Since the new code is
982 more correct (if you have two constants where the first one is a
983 prefix of the second one, the first constant B<never> gets defined),
984 less lossy (it uses integers for integer constant, as opposed to the
985 old code that used floating point numbers even for integer constants),
986 and slightly faster, you might want to consider regenerating your
987 extension code (the new scheme makes regenerating easy).
988 L<h2xs> now also supports C trigraphs.
992 C<libnetcfg> has been added to configure the libnet.
996 C<perlbug> is now much more robust. It also sends the bug report to
997 perl.org, not perl.com.
1001 C<perlcc> has been rewritten and its user interface (that is,
1002 command line) is much more like that of the UNIX C compiler, cc.
1006 C<perlivp> is a new Installation Verification Procedure utility
1007 for running any time after installing Perl.
1011 C<pod2html> now allows specifying a cache directory.
1015 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1016 implementation of sed in Perl: you can use the sed functionality by
1017 using the C<psed> utility.)
1021 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1025 C<xsubpp> now supports OUT keyword.
1029 =head1 New Documentation
1035 perl56delta details the changes between the 5.005 release and the
1040 perlclib documents the internal replacements for standard C library
1041 functions. (Interesting only for extension writers and Perl core
1046 perldebtut is a Perl debugging tutorial.
1050 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1054 perlintro is a gentle introduction to Perl.
1058 perliol documents the internals of PerlIO with layers.
1062 perlmodstyle is a style guide for writing modules.
1066 perlnewmod tells about writing and submitting a new module.
1070 perlpacktut is a pack() tutorial.
1074 perlpod has been rewritten to be clearer and to record the best
1075 practices gathered over the years.
1079 perlpodspec is a more formal specification of the pod format,
1080 mainly of interest for writers of pod applications, not to
1081 people writing in pod.
1085 perlretut is a regular expression tutorial.
1089 perlrequick is a regular expressions quick-start guide.
1090 Yes, much quicker than perlretut.
1094 perltodo has been updated.
1098 perltootc has been renamed as perltooc (to not to conflict
1099 with perltoot in filesystems restricted to "8.3" names)
1103 perluniintro is an introduction to using Unicode in Perl
1104 (perlunicode is more of a reference)
1108 perlutil explains the command line utilities packaged with the Perl
1113 The following platform-specific documents are available before
1114 the installation as README.I<platform>, and after the installation
1117 perlaix perlamiga perlapollo perlbeos perlbs2000
1118 perlce perlcygwin perldgux perldos perlepoc perlhpux
1119 perlhurd perlmachten perlmacos perlmint perlmpeix
1120 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1121 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1127 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1128 confusion with the Perl POSIX module.
1132 The documentation for the WinCE platform is called "CE", to avoid
1133 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1137 =head1 Performance Enhancements
1143 map() that changes the size of the list should now work faster.
1147 sort() has been changed to use primarily mergesort internally as
1148 opposed to the earlier quicksort. For very small lists this may
1149 result in slightly slower sorting times, but in general the speedup
1150 should be at least 20%. Additional bonuses are that the worst case
1151 behaviour of sort() is now better (in computer science terms it now
1152 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1153 worst-case run time behaviour), and that sort() is now stable
1154 (meaning that elements with identical keys will stay ordered as they
1155 were before the sort). See the C<sort> pragma for information.
1157 The story in more detail: suppose you want to serve yourself a little
1160 @digits = ( 3,1,4,1,5,9 );
1162 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1163 Which C<1> comes first is hard to know, since one C<1> looks pretty
1164 much like any other. You can regard this as totally trivial,
1165 or somewhat profound. However, if you just want to sort the even
1166 digits ahead of the odd ones, then what will
1168 sort { ($a % 2) <=> ($b % 2) } @digits;
1170 yield? The only even digit, C<4>, will come first. But how about
1171 the odd numbers, which all compare equal? With the quicksort algorithm
1172 used to implement Perl 5.6 and earlier, the order of ties is left up
1173 to the sort. So, as you add more and more digits of Pi, the order
1174 in which the sorted even and odd digits appear will change.
1175 and, for sufficiently large slices of Pi, the quicksort algorithm
1176 in Perl 5.8 won't return the same results even if reinvoked with the
1177 same input. The justification for this rests with quicksort's
1178 worst case behavior. If you run
1180 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1182 (something you might approximate if you wanted to merge two sorted
1183 arrays using sort), doubling $N doesn't just double the quicksort time,
1184 it I<quadruples> it. Quicksort has a worst case run time that can
1185 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1186 on patterns that may well arise in normal use. You won't notice this
1187 for small arrays, but you I<will> notice it with larger arrays,
1188 and you may not live long enough for the sort to complete on arrays
1189 of a million elements. So the 5.8 quicksort scrambles large arrays
1190 before sorting them, as a statistical defence against quadratic behaviour.
1191 But that means if you sort the same large array twice, ties may be
1192 broken in different ways.
1194 Because of the unpredictability of tie-breaking order, and the quadratic
1195 worst-case behaviour, quicksort was I<almost> replaced completely with
1196 a stable mergesort. I<Stable> means that ties are broken to preserve
1197 the original order of appearance in the input array. So
1199 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1201 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1202 appear in the output in the same order they appeared in the input.
1203 Mergesort has worst case O(NlogN) behaviour, the best value
1204 attainable. And, ironically, this mergesort does particularly
1205 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1206 in O(N) time. But quicksort was rescued at the last moment because
1207 it is faster than mergesort on certain inputs and platforms.
1208 For example, if you really I<don't> care about the order of even
1209 and odd digits, quicksort will run in O(N) time; it's very good
1210 at sorting many repetitions of a small number of distinct elements.
1211 The quicksort divide and conquer strategy works well on platforms
1212 with relatively small, very fast, caches. Eventually, the problem gets
1213 whittled down to one that fits in the cache, from which point it
1214 benefits from the increased memory speed.
1216 Quicksort was rescued by implementing a sort pragma to control aspects
1217 of the sort. The B<stable> subpragma forces stable behaviour,
1218 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1219 subpragmas are heavy-handed ways to select the underlying implementation.
1220 The leading C<_> is a reminder that these subpragmas may not survive
1221 beyond 5.8. More appropriate mechanisms for selecting the implementation
1222 exist, but they wouldn't have arrived in time to save quicksort.
1226 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1227 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1228 reasonably fast while producing a much better spread of values than
1229 the old hashing algorithm (originally by Chris Torek, later tweaked by
1230 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1231 all 3-char printable ASCII keys comes much closer to passing the
1232 DIEHARD random number generation tests. According to perlbench, this
1233 change has not affected the overall speed of Perl.
1237 unshift() should now be noticeably faster.
1241 =head1 Installation and Configuration Improvements
1243 =head2 Generic Improvements
1249 INSTALL now explains how you can configure Perl to use 64-bit
1250 integers even on non-64-bit platforms.
1254 Policy.sh policy change: if you are reusing a Policy.sh file
1255 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1256 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1257 them will now be changed to the new prefix, /foo/bar. (Previously
1258 only $prefix changed.) If you do not like this new behaviour,
1259 specify prefix, siteprefix, and vendorprefix explicitly.
1263 A new optional location for Perl libraries, otherlibdirs, is available.
1264 It can be used for example for vendor add-ons without disturbing Perl's
1265 own library directories.
1269 In many platforms the vendor-supplied 'cc' is too stripped-down to
1270 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1271 to be the case and 'cc' does not seem to be the GNU C compiler
1272 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1276 gcc needs to closely track the operating system release to avoid
1277 build problems. If Configure finds that gcc was built for a different
1278 operating system release than is running, it now gives a clearly visible
1279 warning that there may be trouble ahead.
1283 If binary compatibility with the 5.005 release is not wanted, Configure
1284 no longer suggests including the 5.005 modules in @INC.
1288 Configure C<-S> can now run non-interactively.
1292 configure.gnu now works with options with whitespace in them.
1296 installperl now outputs everything to STDERR.
1300 $Config{byteorder} is now computed dynamically (this is more robust
1301 with "fat binaries" where an executable image contains binaries for
1302 more than one binary platform.)
1306 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1307 get appended to the $Config{archname} (also known as $^O) anymore.
1308 Instead, if you explicitly choose not to use perlio (Configure command
1309 line option -Uuseperlio), you will get "-stdio" appended.
1313 Another change related to the architecture name is that "-64all"
1314 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1315 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1319 In AFS installations one can configure the root of the AFS to be
1320 somewhere else than the default F</afs> by using the Configure
1321 parameter C<-Dafsroot=/some/where/else>.
1325 APPLLIB_EXP, a less-know configuration-time definition, has been
1326 documented. It can be used to prepend site-specific directories
1327 to Perl's default search path (@INC), see INSTALL for information.
1331 The version of Berkeley DB used when the Perl (and, presumably, the
1332 DB_File extension) was built is now available as
1333 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1334 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1335 DB_VERSION_PATCH_CFG> from C.
1339 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1340 has been documented in INSTALL.
1344 If you have CPAN access (either network or a local copy such as a
1345 CD-ROM) you can during specify extra modules to Configure to build and
1346 install with Perl using the -Dextras=... option. See INSTALL for
1351 In addition to config.over a new override file, config.arch, is
1352 available. That is supposed to be used by hints file writers for
1353 architecture-wide changes (as opposed to config.over which is for
1358 If your file system supports symbolic links you can build Perl outside
1359 of the source directory by
1361 mkdir /tmp/perl/build/directory
1362 cd /tmp/perl/build/directory
1363 sh /path/to/perl/source/Configure -Dmksymlinks ...
1365 This will create in /tmp/perl/build/directory a tree of symbolic links
1366 pointing to files in /path/to/perl/source. The original files are left
1367 unaffected. After Configure has finished you can just say
1371 and Perl will be built and tested, all in /tmp/perl/build/directory.
1375 For Perl developers several new make targets for profiling
1376 and debugging have been added, see L<perlhack>.
1382 Use of the F<gprof> tool to profile Perl has been documented in
1383 L<perlhack>. There is a make target called "perl.gprof" for
1384 generating a gprofiled Perl executable.
1388 If you have GCC 3, there is a make target called "perl.gcov" for
1389 creating a gcoved Perl executable for coverage analysis. See
1394 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1395 have been added, see L<perlhack> for more information about pixie and
1402 Guidelines of how to construct minimal Perl installations have
1403 been added to INSTALL.
1407 The Thread extension is now not built at all under ithreads
1408 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1409 Thread extension requires being Configured with C<-Duse5005threads>).
1411 But note that the Thread.pm interface is now shared by both
1416 =head2 New Or Improved Platforms
1418 For the list of platforms known to support Perl,
1419 see L<perlport/"Supported Platforms">.
1425 AIX dynamic loading should be now better supported.
1429 AIX should now work better with gcc, threads, and 64-bitness. Also the
1430 long doubles support in AIX should be better now. See L<perlaix>.
1434 After a long pause, AmigaOS has been verified to be happy with Perl.
1438 AtheOS (http://www.atheos.cx/) is a new platform.
1442 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1446 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1450 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1451 have been regained. Many test suite tests still fail and the
1452 co-existence of Unicode and EBCDIC isn't quite settled, but the
1453 situation is much better than with Perl 5.6. See L<perlos390>,
1454 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1458 Building perl with -Duseithreads or -Duse5005threads now works under
1459 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1460 need a thread library package installed. See README.hpux.
1464 MacOS Classic (MacPerl has of course been available since
1465 perl 5.004 but now the source code bases of standard Perl
1466 and MacPerl have been synchronised)
1470 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1471 filesystems. (The case-insensitivity confused the Perl build process.)
1475 NCR MP-RAS is now supported.
1479 NetWare from Novell is now supported. See L<perlnetware>.
1483 NonStop-UX is now supported.
1487 Amdahl UTS UNIX mainframe platform is now supported.
1491 WinCE is now supported. See L<perlce>.
1495 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1496 support for dynamic loading. This is not selected by default,
1497 however, you must specify -Dusedl in the arguments of Configure.
1501 =head1 Selected Bug Fixes
1503 Numerous memory leaks and uninitialized memory accesses have been
1504 hunted down. Most importantly anonymous subs used to leak quite
1511 The autouse pragma didn't work for Multi::Part::Function::Names.
1515 chop(@list) in list context returned the characters chopped in
1516 reverse order. This has been reversed to be in the right order.
1520 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1521 when building the Perl binary. The only exception to this is SunOS 4.x,
1526 The behaviour of non-decimal but numeric string constants such as
1527 "0x23" was platform-dependent: in some platforms that was seen as 35,
1528 in some as 0, in some as a floating point number (don't ask). This
1529 was caused by Perl using the operating system libraries in a situation
1530 where the result of the string to number conversion is undefined: now
1531 Perl consistently handles such strings as zero in numeric contexts.
1535 The order of DESTROYs has been made more predictable.
1539 Several debugger fixes: exit code now reflects the script exit code,
1540 condition C<"0"> now treated correctly, the C<d> command now checks
1541 line number, the C<$.> no longer gets corrupted, all debugger output now
1542 goes correctly to the socket if RemotePort is set.
1546 L<dprofpp> -R didn't work.
1550 C<*foo{FORMAT}> now works.
1554 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1555 the Tk extension with 5.6.0.)
1559 Lexicals I: lexicals outside an eval "" weren't resolved
1560 correctly inside a subroutine definition inside the eval "" if they
1561 were not already referenced in the top level of the eval""ed code.
1565 Lexicals II: lexicals leaked at file scope into subroutines that
1566 were declared before the lexicals.
1570 Lexical warnings now propagating correctly between scopes.
1574 Line renumbering with eval and C<#line> now works.
1578 Fixed numerous memory leaks, especially in eval "".
1582 mkdir() now ignores trailing slashes in the directory name,
1583 as mandated by POSIX.
1587 Some versions of glibc have a broken modfl(). This affects builds
1588 with C<-Duselongdouble>. This version of Perl detects this brokenness
1589 and has a workaround for it. The glibc release 2.2.2 is known to have
1590 fixed the modfl() bug.
1594 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1595 return 27406, instead of 27047).
1599 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1600 more compatible with 5.005. Infinity is now recognised as a number.
1604 Attributes (like :shared) didn't work with our().
1608 our() variables will not cause "will not stay shared" warnings.
1612 pack "Z" now correctly terminates the string with "\0".
1616 Fix password routines which in some shadow password platforms
1617 (e.g. HP-UX) caused getpwent() to return every other entry.
1621 The PERL5OPT environment variable (for passing command line arguments
1622 to Perl) didn't work for more than a single group of options.
1626 PERL5OPT with embedded spaces didn't work.
1630 printf() no longer resets the numeric locale to "C".
1634 C<q(a\\b)> now parses correctly as C<'a\\b'>.
1638 Printing quads (64-bit integers) with printf/sprintf now works
1639 without the q L ll prefixes (assuming you are on a quad-capable platform).
1643 Regular expressions on references and overloaded scalars now work.
1647 Right-hand side magic (GMAGIC) could in many cases such as string
1648 concatenation be invoked too many times.
1652 scalar() now forces scalar context even when used in void context.
1656 SOCKS support is now much more robust.
1660 sort() arguments are now compiled in the right wantarray context
1661 (they were accidentally using the context of the sort() itself).
1665 Changed the POSIX character class C<[[:space:]]> to include the (very
1666 rarely used) vertical tab character. Added a new POSIX-ish character
1667 class C<[[:blank:]]> which stands for horizontal whitespace
1668 (currently, the space and the tab).
1672 The tainting behaviour of sprintf() has been rationalized. It does
1673 not taint the result of floating point formats anymore, making the
1674 behaviour consistent with that of string interpolation.
1678 The regular expression captured submatches ($1, $2, ...) are now
1679 more consistently unset if the match fails, instead of leaving false
1680 data lying around in them.
1684 Sys::Syslog ignored the C<LOG_AUTH> constant.
1688 All but the first argument of the IO syswrite() method are now optional.
1692 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1693 in multiple threads simultaneously are now thread-safe.
1697 Tie::ARRAY SPLICE method was broken.
1701 Allow read-only string on left hand side of non-modifying tr///.
1705 Several Unicode fixes.
1711 BOMs (byte order marks) in the beginning of Perl files
1712 (scripts, modules) should now be transparently skipped.
1713 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1717 The character tables have been updated to Unicode 3.1.1.
1721 Comparing with utf8 data does not magically upgrade non-utf8 data
1726 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1730 Concatenation with the C<.> operator or via variable interpolation,
1731 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1732 substitution with C<s///>, single-quoted UTF8, should now work.
1736 The C<tr///> operator now works. Note that the C<tr///CU>
1737 functionality has been removed (but see pack('U0', ...)).
1741 C<eval "v200"> now works.
1745 Zero entries were missing from the Unicode classes like C<IsDigit>.
1751 =head2 Platform Specific Changes and Fixes
1759 Perl now works on post-4.0 BSD/OSes.
1765 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
1771 Numerous updates; currently synchronised with Cygwin 1.1.4.
1775 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1781 EPOC update after Perl 5.6.0. See README.epoc.
1787 Perl now works on post-3.0 FreeBSDs.
1793 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1799 Numerous compilation flag and hint enhancements; accidental mixing
1800 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1810 Long doubles should now work (see INSTALL).
1814 Linux previously had problems related to sockaddrlen when using
1815 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1823 Compilation of the standard Perl distribution in MacOS Classic should
1824 now work if you have the Metrowerks development environment and
1825 the missing Mac-specific toolkit bits. Contact the macperl mailing
1832 MPE/iX update after Perl 5.6.0. See README.mpeix.
1838 Perl now works on NetBSD/sparc.
1844 Now works with usethreads (see INSTALL).
1850 64-bitness using the Sun Workshop compiler now works.
1854 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1856 The operating system version letter now recorded in $Config{osvers}.
1857 Allow compiling with gcc (previously explicitly forbidden). Compiling
1858 with gcc still not recommended because buggy code results, even with
1865 Fixed various alignment problems that lead into core dumps either
1866 during build or later; no longer dies on math errors at runtime;
1867 now using full quad integers (64 bits), previously was using
1868 only 46 bit integers for speed.
1874 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
1875 (see INSTALL); now works with Perl's malloc.
1885 accept() no longer leaks memory.
1889 Borland C++ v5.5 is now a supported compiler that can build Perl.
1890 However, the generated binaries continue to be incompatible with those
1891 generated by the other supported compilers (GCC and Visual C++).
1895 Better chdir() return value for a non-existent directory.
1899 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
1903 New %ENV entries now propagate to subprocesses.
1907 $ENV{LIB} now used to search for libs under Visual C.
1911 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
1912 Other bugs in chdir() and Cwd::cwd() have also been fixed.
1916 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
1920 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
1924 The makefiles now provide a single switch to bulk-enable all the features
1925 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
1929 Allow REG_EXPAND_SZ keys in the registry.
1933 Can now send() from all threads, not just the first one.
1937 Fake signal handling reenabled, bugs and all.
1941 Less stack reserved per thread so that more threads can run
1942 concurrently. (Still 16M per thread.)
1946 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
1947 (works better when perl is running as service).
1951 Better UNC path handling under ithreads.
1955 wait() and waitpid() now work much better.
1959 winsock handle leak fixed.
1965 =head1 New or Changed Diagnostics
1971 All regular expression compilation error messages are now hopefully
1972 easier to understand both because the error message now comes before
1973 the failed regex and because the point of failure is now clearly
1974 marked by a C<E<lt>-- HERE> marker.
1978 The various "opened only for", "on closed", "never opened" warnings
1979 drop the C<main::> prefix for filehandles in the C<main> package,
1980 for example C<STDIN> instead of C<main::STDIN>.
1984 The "Unrecognized escape" warning has been extended to include C<\8>,
1985 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
1989 Two new debugging options have been added: if you have compiled your
1990 Perl with debugging, you can use the -DT and -DR options to trace
1991 tokenising and to add reference counts to displaying variables,
1996 If an attempt to use a (non-blessed) reference as an array index
1997 is made, a warning is given.
2001 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2002 now give a warning. This may be a problem for generated and evaled
2007 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2008 using the C<"C"> format you will get an optional warning. Similarly
2009 for the C<"c"> format and a number less than -128 or more than 127.
2013 Certain regex modifiers such as C<(?o)> make sense only if applied to
2014 the entire regex. You will an optional warning if you try to do otherwise.
2018 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2019 has been deprecated for a while. Now you will get an optional warning.
2023 =head1 Changed Internals
2029 perlapi.pod (a companion to perlguts) now attempts to document the
2034 You can now build a really minimal perl called microperl.
2035 Building microperl does not require even running Configure;
2036 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2037 many assumptions, some of which may be too bold; the resulting
2038 executable may crash or otherwise misbehave in wondrous ways.
2039 For careful hackers only.
2043 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2044 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2045 interfaces to the publicised API. For the full list of the available
2046 APIs see L<perlapi>.
2050 Made possible to propagate customised exceptions via croak()ing.
2054 Now xsubs can have attributes just like subs.
2058 dTHR and djSP have been obsoleted; the former removed (because it's
2059 a no-op) and the latter replaced with dSP.
2063 PERL_OBJECT has been completely removed.
2067 The MAGIC constants (e.g. C<'P'>) have been macrofied
2068 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2069 and maintainability.
2073 The regex compiler now maintains a structure that identifies nodes in
2074 the compiled bytecode with the corresponding syntactic features of the
2075 original regex expression. The information is attached to the new
2076 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2077 complete information.
2081 The C code has been made much more C<gcc -Wall> clean. Some warning
2082 messages still remain in some platforms, so if you are compiling with
2083 gcc you may see some warnings about dubious practices. The warnings
2084 are being worked on.
2088 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2092 Documentation on how to use the Perl source repository has been added
2093 to F<Porting/repository.pod>.
2097 There are now several profiling make targets.
2101 =head1 Security Vulnerability Closed
2103 (This change was already made in 5.7.0 but bears repeating here.)
2105 A potential security vulnerability in the optional suidperl component
2106 of Perl was identified in August 2000. suidperl is neither built nor
2107 installed by default. As of November 2001 the only known vulnerable
2108 platform is Linux, most likely all Linux distributions. CERT and
2109 various vendors and distributors have been alerted about the vulnerability.
2110 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2111 for more information.
2113 The problem was caused by Perl trying to report a suspected security
2114 exploit attempt using an external program, /bin/mail. On Linux
2115 platforms the /bin/mail program had an undocumented feature which
2116 when combined with suidperl gave access to a root shell, resulting in
2117 a serious compromise instead of reporting the exploit attempt. If you
2118 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2119 suidperl is not installed, you are safe.
2121 The exploit attempt reporting feature has been completely removed from
2122 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2123 from all the Perl 5.7 releases), so that particular vulnerability
2124 isn't there anymore. However, further security vulnerabilities are,
2125 unfortunately, always possible. The suidperl functionality is most
2126 probably going to be removed in Perl 5.10. In any case, suidperl
2127 should only be used by security experts who know exactly what they are
2128 doing and why they are using suidperl instead of some other solution
2129 such as sudo (see http://www.courtesan.com/sudo/).
2133 Several new tests have been added, especially for the F<lib>
2134 subsection. There are now about 34 000 individual tests (spread over
2135 about 530 test scripts), in the regression suite (5.6.1 has about
2136 11700 tests, in 258 test scripts) Many of the new tests are introduced
2137 by the new modules, but still in general Perl is now more thoroughly
2140 Because of the large number of tests, running the regression suite
2141 will take considerably longer time than it used to: expect the suite
2142 to take up to 4-5 times longer to run than in perl 5.6. In a really
2143 fast machine you can hope to finish the suite in about 5 minutes
2146 The tests are now reported in a different order than in earlier Perls.
2147 (This happens because the test scripts from under t/lib have been moved
2148 to be closer to the library/extension they are testing.)
2150 =head1 Known Problems
2158 In AIX 4.2 Perl extensions that use C++ functions that use statics
2159 may have problems in that the statics are not getting initialized.
2160 In newer AIX releases this has been solved by linking Perl with
2161 the libC_r library, but unfortunately in AIX 4.2 the said library
2162 has an obscure bug where the various functions related to time
2163 (such as time() and gettimeofday()) return broken values, and
2164 therefore in AIX 4.2 Perl is not linked against the libC_r.
2168 vac 5.0.0.0 May Produce Buggy Code For Perl
2170 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2171 resulting in few random tests failing, but when the failing tests
2172 are run by hand, they succeed. We suggest upgrading to at least
2173 vac version 5.0.1.0, that has been known to compile Perl correctly.
2174 "lslpp -L|grep vac.C" will tell you the vac version.
2178 =head2 Amiga Perl Invoking Mystery
2180 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2181 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2182 known but the current suspect is the F<ixemul> library.
2184 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2186 Don't panic. Read INSTALL 'make test' section instead.
2188 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2190 The subtests 11 and 12 sometimes fail and sometimes work.
2192 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2194 The lib/io_multihomed test may hang in HP-UX if Perl has been
2195 configured to be 64-bit. Because other 64-bit platforms do not hang in
2196 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2197 test attempts to create and connect to "multihomed" sockets (sockets
2198 which have multiple IP addresses).
2200 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2202 If perl is configured with -Duse64bitall, the successful result of the
2203 subtest 10 of lib/posix may arrive before the successful result of the
2204 subtest 9, which confuses the test harness so much that it thinks the
2207 =head2 Linux With Sfio Fails op/misc Test 48
2213 OS/390 has rather many test failures but the situation is actually
2214 better than it was in 5.6.0, it's just that so many new modules and
2215 tests have been added.
2217 Failed Test Stat Wstat Total Fail Failed List of Failed
2218 -----------------------------------------------------------------------------
2219 ../ext/B/Deparse.t 14 1 7.14% 14
2220 ../ext/B/Showlex.t 1 1 100.00% 1
2221 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2223 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2224 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2225 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2226 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2227 ../lib/warnings.t 434 1 0.23% 75
2228 ../lib/ExtUtils.t 27 1 3.70% 25
2229 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2230 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2231 ../lib/User/pwent.t 9 1 11.11% 4
2232 op/pat.t 660 6 0.91% 242-243 424-425
2234 op/split.t 0 9 ?? ?? % ??
2235 op/taint.t 174 3 1.72% 156 162 168
2236 op/tr.t 70 3 4.29% 50 58-59
2237 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2239 =head2 op/sprintf tests 129 and 130
2241 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2242 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2243 The failing platforms do not comply with the ANSI C Standard, line
2244 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2245 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2246 the printf format "%.0f", most often they produce "0" and "-0".)
2248 =head2 Failure of Thread tests
2250 B<Note that support for 5.005-style threading remains experimental.>
2252 The following tests are known to fail due to fundamental problems in
2253 the 5.005 threading implementation. These are not new failures--Perl
2254 5.005_0x has the same bugs, but didn't have these tests.
2257 t/lib/thr5005.t 19-20
2265 ext/POSIX/sigaction subtests 6 and 13 may fail.
2269 lib/ExtUtils may spuriously claim that subtest 28 failed,
2270 which is interesting since the test only has 27 tests.
2274 Numerous numerical test failures
2276 op/numconvert 209,210,217,218
2278 ext/Time/HiRes/HiRes 9
2279 lib/Math/BigInt/t/bigintpm 1145
2282 These tests fail because of yet unresolved floating point inaccuracies.
2288 There are a few known test failures, see L<perluts>.
2292 Rather a lot of tests are failing in VMS, but actually more tests
2293 succeed in VMS than they used to; it's just that there are many,
2294 many more tests than there used to be.
2296 Here are the known failures from some compiler/platform combinations.
2298 Compaq C V6.2-009 on OpenVMS Alpha V7.3
2300 [.run]switches..........................FAILED on test 1
2301 [-.ext.posix.t]posix....................FAILED on test 10
2302 [-.ext.time.hires]hires.................FAILED on test 17
2303 [-.lib]db...............................FAILED on test 24
2304 [-.lib.net]hostent......................FAILED on test 5
2305 [-.lib.pod.t]basic......................FAILED on test 10
2309 In multi-CPU boxes there are some problems with the I/O buffering:
2310 some output may appear twice.
2312 =head2 Localising a Tied Variable Leaks Memory
2315 tie my %tie_hash => 'Tie::StdHash';
2319 local($tie_hash{Foo}) = 1; # leaks
2321 Code like the above is known to leak memory every time the local()
2324 =head2 Localising Tied Arrays and Hashes Is Broken
2328 doesn't work as one would expect: the old value is restored
2331 =head2 Self-tying of Arrays and Hashes Is Forbidden
2333 Self-tying of arrays and hashes is broken in rather deep and
2334 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2335 frustrated at the mysterious results (core dumps, most often) it is
2336 for now forbidden (you will get a fatal error even from an attempt).
2338 =head2 Variable Attributes are not Currently Usable for Tieing
2340 This limitation will hopefully be fixed in future. (Subroutine
2341 attributes work fine for tieing, see L<Attribute::Handlers>).
2343 One way to run into this limitation is to have a loop variable with
2344 attributes within a loop: the tie is called only once, not for each
2345 iteration of the loop.
2347 =head2 Building Extensions Can Fail Because Of Largefiles
2349 Some extensions like mod_perl are known to have issues with
2350 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2351 default to 64 bits wide, where supported. Modules may fail to compile
2352 at all or compile and work incorrectly. Currently there is no good
2353 solution for the problem, but Configure now provides appropriate
2354 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2355 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2356 having problems can try configuring themselves without the
2357 largefileness. This is admittedly not a clean solution, and the
2358 solution may not even work at all. One potential failure is whether
2359 one can (or, if one can, whether it's a good idea) link together at
2360 all binaries with different ideas about file offsets, all this is
2363 =head2 Unicode Support on EBCDIC Still Spotty
2365 Though mostly working, Unicode support still has problem spots on
2366 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2367 regular expression constructs for code points less than 256: the
2368 pP are testing for Unicode code points, not knowing about EBCDIC.
2370 =head2 The Compiler Suite Is Still Experimental
2372 The compiler suite is slowly getting better but is nowhere near
2375 =head2 The Long Double Support is Still Experimental
2377 The ability to configure Perl's numbers to use "long doubles",
2378 floating point numbers of hopefully better accuracy, is still
2379 experimental. The implementations of long doubles are not yet
2380 widespread and the existing implementations are not quite mature
2381 or standardised, therefore trying to support them is a rare
2382 and moving target. The gain of more precision may also be offset
2383 by slowdown in computations (more bits to move around, and the
2384 operations are more likely to be executed by less optimised
2387 =head1 Reporting Bugs
2389 If you find what you think is a bug, you might check the articles
2390 recently posted to the comp.lang.perl.misc newsgroup and the perl
2391 bug database at http://bugs.perl.org. There may also be
2392 information at http://www.perl.com/perl/, the Perl Home Page.
2394 If you believe you have an unreported bug, please run the B<perlbug>
2395 program included with your release. Be sure to trim your bug down
2396 to a tiny but sufficient test case. Your bug report, along with the
2397 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2398 analysed by the Perl porting team.
2402 The F<Changes> file for exhaustive details on what changed.
2404 The F<INSTALL> file for how to build Perl.
2406 The F<README> file for general stuff.
2408 The F<Artistic> and F<Copying> files for copyright information.
2412 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.