3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release
10 Many of the bug fixes in 5.8.0 were already seen in the 5.6.1
11 maintenance release since the two releases were kept closely
14 If you are upgrading from Perl 5.005_03, you might also want
15 to read L<perl56delta>.
17 =head1 Highlights In 5.8.0
23 Better Unicode support
27 New Thread Implementation
35 Better Numeric Accuracy
43 More Extensive Regression Testing
47 =head1 Incompatible Changes
49 =head2 64-bit platforms and malloc
51 If your pointers are 64 bits wide, the Perl malloc is no longer being
52 used because it does not work well with 8-byte pointers. Also,
53 usually the system mallocs on such platforms are much better optimized
54 for such large memory models than the Perl malloc. Some memory-hungry
55 Perl applications like the PDL don't work well with Perl's malloc.
56 Finally, other applications than Perl (like modperl) tend to prefer
57 the system malloc. Such platforms include Alpha and 64-bit HPPA,
60 =head2 AIX Dynaloading
62 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
63 dlopen interface of AIX instead of the old emulated interface. This
64 change will probably break backward compatibility with compiled
65 modules. The change was made to make Perl more compliant with other
66 applications like modperl which are using the AIX native interface.
68 =head2 Attributes for C<my> variables now handled at run-time.
70 The C<my EXPR : ATTRS> syntax now applies variable attributes at
71 run-time. (Subroutine and C<our> variables still get attributes applied
72 at compile-time.) See L<attributes> for additional details. In particular,
73 however, this allows variable attributes to be useful for C<tie> interfaces,
74 which was a deficiency of earlier releases. Note that the new semantics
75 doesn't work with the Attribute::Handlers module (as of version 0.76).
77 =head2 Socket Extension Dynamic in VMS
79 The Socket extension is now dynamically loaded instead of being
80 statically built in. This may or may not be a problem with ancient
81 TCP/IP stacks of VMS: we do not know since we weren't able to test
82 Perl in such configurations.
84 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
86 Perl now uses IEEE format (T_FLOAT) as the default internal floating
87 point format on OpenVMS Alpha, potentially breaking binary compatibility
88 with external libraries or existing data. G_FLOAT is still available as
89 a configuration option. The default on VAX (D_FLOAT) has not changed.
91 =head2 Different Definition of the Unicode Character Classes \p{In...}
93 As suggested by the Unicode consortium, the Unicode character classes
94 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
95 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
96 constructs are used. This has changed the definition of some of those
99 The difference between scripts and blocks is that scripts are the
100 glyphs used by a language or a group of languages, while the blocks
101 are more artificial groupings of 256 characters based on the Unicode
104 In general this change results in more inclusive Unicode character
105 classes, but changes to the other direction also do take place:
106 for example while the script C<Latin> includes all the Latin
107 characters and their various diacritic-adorned versions, it
108 does not include the various punctuation or digits (since they
109 are not solely C<Latin>).
111 Changes in the character class semantics may have happened if a script
112 and a block happen to have the same name, for example C<Hebrew>.
113 In such cases the script wins and C<\p{InHebrew}> now means the script
114 definition of Hebrew. The block definition in still available,
115 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
116 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
117 of affected character classes, see L<perlunicode/Blocks>.
119 =head2 Perl Parser Stress Tested
121 The Perl parser has been stress tested using both random input and
122 Markov chain input and the few found crashes and lockups have been
125 =head2 REF(...) Instead Of SCALAR(...)
127 A reference to a reference now stringifies as "REF(0x81485ec)" instead
128 of "SCALAR(0x81485ec)" in order to be more consistent with the return
137 The semantics of bless(REF, REF) were unclear and until someone proves
138 it to make some sense, it is forbidden.
142 The obsolete chat2 library that should never have been allowed
143 to escape the laboratory has been decommissioned.
147 The very dusty examples in the eg/ directory have been removed.
148 Suggestions for new shiny examples welcome but the main issue is that
149 the examples need to be documented, tested and (most importantly)
154 The (bogus) escape sequences \8 and \9 now give an optional warning
155 ("Unrecognized escape passed through"). There is no need to \-escape
160 The list of filenames from glob() (or <...>) is now by default sorted
161 alphabetically to be csh-compliant (which is what happened before
162 in most UNIX platforms). (bsd_glob() does still sort platform
163 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
167 Spurious syntax errors generated in certain situations, when glob()
168 caused File::Glob to be loaded for the first time, have been fixed.
172 Although "you shouldn't do that", it was possible to write code that
173 depends on Perl's hashed key order (Data::Dumper does this). The new
174 algorithm "One-at-a-Time" produces a different hashed key order.
175 More details are in L</"Performance Enhancements">.
179 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
180 In future releases this may become a fatal error.
184 The C<package;> syntax (C<package> without an argument) has been
185 deprecated. Its semantics were never that clear and its
186 implementation even less so. If you have used that feature to
187 disallow all but fully qualified variables, C<use strict;> instead.
191 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
192 recognised but now cause fatal errors. The previous behaviour of
193 ignoring them by default and warning if requested was unacceptable
194 since it, in a way, falsely promised that the features could be used.
198 The current user-visible implementation of pseudo-hashes (the weird
199 use of the first array element) is deprecated starting from Perl 5.8.0
200 and will be removed in Perl 5.10.0, and the feature will be
201 implemented differently. Not only is the current interface rather
202 ugly, but the current implementation slows down normal array and hash
203 use quite noticeably. The C<fields> pragma interface will remain
208 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
212 After years of trying the suidperl is considered to be too complex to
213 ever be considered truly secure. The suidperl functionality is likely
214 to be removed in a future release.
218 The long deprecated uppercase aliases for the string comparison
219 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
223 The tr///C and tr///U features have been removed and will not return;
224 the interface was a mistake. Sorry about that. For similar
225 functionality, see pack('U0', ...) and pack('C0', ...).
229 =head1 Core Enhancements
231 =head2 PerlIO is Now The Default
237 IO is now by default done via PerlIO rather than system's "stdio".
238 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
239 handle's behaviour. Layers can be specified at open time via 3-arg
242 open($fh,'>:crlf :utf8', $path) || ...
244 or on already opened handles via extended C<binmode>:
246 binmode($fh,':encoding(iso-8859-7)');
248 The built-in layers are: unix (low level read/write), stdio (as in
249 previous Perls), perlio (re-implementation of stdio buffering in a
250 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
251 but available on any platform). A mmap layer may be available if
252 platform supports it (mostly UNIXes).
254 Layers to be applied by default may be specified via the 'open' pragma.
256 See L</"Installation and Configuration Improvements"> for the effects
257 of PerlIO on your architecture name.
261 File handles can be marked as accepting Perl's internal encoding of Unicode
262 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
264 open($fh,">:utf8","Uni.txt");
266 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
267 for you since it's not UTF-8 what you will be getting but instead
268 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
269 http://www.unicode.org/unicode/reports/tr16/ for more information.
270 In future releases this naming may change.
274 File handles can translate character encodings from/to Perl's internal
275 Unicode form on read/write via the ":encoding()" layer.
279 File handles can be opened to "in memory" files held in Perl scalars via:
281 open($fh,'>', \$variable) || ...
285 Anonymous temporary files are available without need to
286 'use FileHandle' or other module via
288 open($fh,"+>", undef) || ...
290 That is a literal undef, not an undefined value.
294 The list form of C<open> is now implemented for pipes (at least on UNIX):
296 open($fh,"-|", 'cat', '/etc/motd')
298 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
303 =head2 Signals Are Now Safe
305 Perl used to be fragile in that signals arriving at inopportune moments
306 could corrupt Perl's internal state. Now Perl postpones handling of
307 signals until it's safe.
309 =head2 Unicode Overhaul
311 Unicode in general should be now much more usable than in Perl 5.6.0
312 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
313 regular expressions should work now, Unicode in tr/// should work now,
314 Unicode in I/O should work now.
320 The Unicode Character Database coming with Perl has been upgraded
321 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
325 For developers interested in enhancing Perl's Unicode capabilities:
326 almost all the UCD files are included with the Perl distribution in
327 the lib/unicore subdirectory. The most notable omission, for space
328 considerations, is the Unihan database.
332 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
333 added. "Blank" is like C isblank(), that is, it contains only
334 "horizontal whitespace" (the space character is, the newline isn't),
335 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
336 isn't, since that includes the vertical tabulator character, whereas
341 =head2 Understanding of Numbers
343 In general a lot of fixing has happened in the area of Perl's
344 understanding of numbers, both integer and floating point. Since in
345 many systems the standard number parsing functions like C<strtoul()>
346 and C<atof()> seem to have bugs, Perl tries to work around their
347 deficiencies. This results hopefully in more accurate numbers.
349 Perl now tries internally to use integer values in numeric conversions
350 and basic arithmetics (+ - * /) if the arguments are integers, and
351 tries also to keep the results stored internally as integers.
352 This change leads to often slightly faster and always less lossy
353 arithmetics. (Previously Perl always preferred floating point numbers
356 =head2 Miscellaneous Enhancements
362 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
363 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
367 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
368 in multiple arguments.)
372 END blocks are now run even if you exit/die in a BEGIN block.
373 Internally, the execution of END blocks is now controlled by
374 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
375 behaviour for Perl embedders. This will default in 5.10. See
380 Formats now support zero-padded decimal fields.
384 Lvalue subroutines can now return C<undef> in list context.
385 However, the lvalue subroutine feature still remains experimental.
389 A new special regular expression variable has been introduced:
390 C<$^N>, which contains the most-recently closed group (submatch).
394 C<no Module;> now works even if there is no "sub unimport" in the Module.
398 The numerical comparison operators return C<undef> if either operand
399 is a NaN. Previously the behaviour was unspecified.
403 The following builtin functions are now overridable: each(), keys(),
404 pop(), push(), shift(), splice(), unshift().
408 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
412 my __PACKAGE__ $obj now works.
416 The printf() and sprintf() now support parameter reordering using the
417 C<%\d+\$> and C<*\d+\$> syntaxes. For example
419 print "%2\$s %1\$s\n", "foo", "bar";
421 will print "bar foo\n". This feature helps in writing
422 internationalised software, and in general when the order
423 of the parameters can vary.
427 prototype(\&) is now available.
431 prototype(\[$@%&]) is now available to implicitly create references
432 (useful for example if you want to emulate the tie() interface).
436 untie() will now call an UNTIE() hook if it exists. See L<perltie>
441 L<utime> now supports C<utime undef, undef, @files> to change the
442 file timestamps to the current time.
446 The rules for allowing underscores (underbars) in numeric constants
447 have been relaxed and simplified: now you can have an underscore
448 simply B<between digits>.
452 =head1 Modules and Pragmata
454 =head2 New Modules and Pragmata
460 B<B::Concise> is a new compiler backend for walking the Perl syntax
461 tree, printing concise info about ops, from Stephen McCamant. The
462 output is highly customisable. See L<B::Concise>.
466 C<Class::ISA> for reporting the search path for a class's ISA tree,
467 by Sean Burke, has been added. See L<Class::ISA>.
471 C<Cwd> has now a split personality: if possible, an XS extension is
472 used, (this will hopefully be faster, more secure, and more robust)
473 but if not possible, the familiar Perl implementation is used.
477 C<Devel::PPPort>, originally from Kenneth Albanowski and now
478 maintained by Paul Marquess, has been added. It is primarily used
479 by C<h2xs> to enhance portability of of XS modules between different
484 C<Digest>, frontend module for calculating digests (checksums), from
485 Gisle Aas, has been added. See L<Digest>.
489 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
490 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
492 use Digest::MD5 'md5_hex';
494 $digest = md5_hex("Thirsty Camel");
496 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
498 NOTE: the C<MD5> backward compatibility module is deliberately not
499 included since its further use is discouraged.
503 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
504 between different character encodings. Support for Unicode,
505 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
506 compiled in to the module. Several other encodings (like Japanese,
507 Chinese, and MacIntosh encodings) are included and will be loaded at
508 runtime. See L<Encode>.
510 Any encoding supported by Encode module is also available to the
511 ":encoding()" layer if PerlIO is used.
515 C<I18N::Langinfo> can be use to query locale information.
516 See L<I18N::Langinfo>.
520 C<I18N::LangTags> has functions for dealing with RFC3066-style
521 language tags, by Sean Burke. See L<I18N::LangTags>.
525 C<ExtUtils::Constant> is a new tool for extension writers for
526 generating XS code to import C header constants, by Nicholas Clark.
527 See L<ExtUtils::Constant>.
531 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
532 from Damian Conway. See L<Filter::Simple>.
538 use Filter::Simple sub {
539 while (my ($from, $to) = splice @_, 0, 2) {
548 use MyFilter qr/red/ => 'green';
550 print "red\n"; # this code is filtered, will print "green\n"
551 print "bored\n"; # this code is filtered, will print "bogreen\n"
555 print "red\n"; # this code is not filtered, will print "red\n"
559 C<File::Temp> allows one to create temporary files and directories in
560 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
564 C<Filter::Util::Call> provides you with the framework to write
565 I<Source Filters> in Perl, from Paul Marquess. For most uses the
566 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
570 L<libnet> is a collection of perl5 modules related to network
571 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
572 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
574 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
578 C<List::Util> is a selection of general-utility list subroutines, like
579 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
583 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
584 C<Locale::Language>, from Neil Bowers, have been added. They provide the
585 codes for various locale standards, such as "fr" for France, "usd" for
586 US Dollar, and "jp" for Japanese.
590 $country = code2country('jp'); # $country gets 'Japan'
591 $code = country2code('Norway'); # $code gets 'no'
593 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
594 and L<Locale::Language>.
598 C<Locale::Maketext> is localization framework from Sean Burke. See
599 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
600 article about software localization, originally published in The Perl
601 Journal #13, republished here with kind permission.
605 C<Memoize> can make your functions faster by trading space for time,
606 from Mark-Jason Dominus. See L<Memoize>.
610 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
611 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
616 $encoded = encode_base64('Aladdin:open sesame');
617 $decoded = decode_base64($encoded);
619 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
625 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
626 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
627 Extensions)>, from Gisle Aas.
629 use MIME::QuotedPrint;
631 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
632 $decoded = decode_qp($encoded);
634 print $encoded, "\n"; # "Smiley in Unicode: =263A"
636 MIME::QuotedPrint has been enhanced to provide the basic methods
637 necessary to use it with PerlIO::Via as in :
639 use MIME::QuotedPrint;
640 open($fh,">Via(MIME::QuotedPrint)",$path);
642 See L<MIME::QuotedPrint>.
646 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
651 C<open> is a new pragma for setting the default I/O disciplines
656 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
657 Perl scalars as discussed above, from Nick Ing-Simmons. It also
658 serves as an example of a loadable PerlIO layer. Other future
659 possibilities include PerlIO::Array and PerlIO::Code.
660 See L<PerlIO::Scalar>.
664 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
665 functionality provided by a class (typically implemented in perl
666 code), from Nick Ing-Simmons.
668 use MIME::QuotedPrint;
669 open($fh,">Via(MIME::QuotedPrint)",$path);
671 This will automatically convert everything output to C<$fh>
672 to Quoted-Printable. See L<PerlIO::Via>.
676 C<Pod::ParseLink>, by Russ Allbery, has been added,
677 to parse LZ<><> links in pods as described in the new
682 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
683 It converts POD data to formatted overstrike text.
684 See L<Pod::Text::Overstrike>.
688 C<Scalar::Util> is a selection of general-utility scalar subroutines,
689 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
693 C<sort> is a new pragma for controlling the behaviour of sort().
697 C<Storable> gives persistence to Perl data structures by allowing the
698 storage and retrieval of Perl data to and from files in a fast and
699 compact binary format, from Raphael Manfredi. See L<Storable>.
703 C<Switch>, from Damian Conway, has been added. Just by saying
707 you have C<switch> and C<case> available in Perl.
713 case 1 { print "number 1" }
714 case "a" { print "string a" }
715 case [1..10,42] { print "number in list" }
716 case (@array) { print "number in list" }
717 case /\w+/ { print "pattern" }
718 case qr/\w+/ { print "pattern" }
719 case (%hash) { print "entry in hash" }
720 case (\%hash) { print "entry in hash" }
721 case (\&sub) { print "arg to subroutine" }
722 else { print "previous case not true" }
729 C<Test::More> is yet another framework for writing test scripts,
730 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
734 C<Test::Simple> has basic utilities for writing tests, by Michael
735 Schwern. See L<Test::Simple>.
739 C<Text::Balanced> has been added, for extracting delimited text
740 sequences from strings, from Damian Conway.
742 use Text::Balanced 'extract_delimited';
744 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
746 $a will be "'never say never'", $b will be ', he never said'.
748 In addition to extract_delimited() there are also extract_bracketed(),
749 extract_quotelike(), extract_codeblock(), extract_variable(),
750 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
751 gen_extract_tagged(). With these you can implement rather advanced
752 parsing algorithms. See L<Text::Balanced>.
756 C<threads> is an interface to interpreter threads, by Arthur Bergman.
757 Interpreter threads (ithreads) is the new thread model introduced in
758 Perl 5.6 but only available as an internal interface for extension
759 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
763 C<threads::shared> allows data sharing for interpreter threads, from
764 Arthur Bergman. In the ithreads model any data sharing between
765 threads must be explicit, as opposed to the old 5.005 thread model
766 where data sharing was implicit. See L<threads::shared>.
770 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
771 references (unlike the standard Tie::RefHash) The module is contained
772 within Tie::RefHash, see L<Tie::RefHash>.
776 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
777 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
781 C<Unicode::UCD> offers a querying interface to the Unicode Character
782 Database. See L<Unicode::UCD>.
786 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
787 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
791 C<Unicode::Normalize> implements the various Unicode normalization
792 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
796 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
797 typemaps. Nothing gets installed but for extension writers the code
802 =head2 Updated And Improved Modules and Pragmata
808 The following independently supported modules have been updated to the
809 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
810 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
811 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
812 Term::ANSIColor, Test, Text-Tabs+Wrap.
816 The attributes::reftype() now works on tied arguments.
820 AutoLoader can now be disabled with C<no AutoLoader;>.
824 B::Deparse has been significantly enhanced. It now can deparse almost
825 all of the standard test suite (so that the tests still succeed).
826 There is a make target "test.deparse" for trying this out.
830 Class::Struct can now define the classes in compile time.
834 Class::Struct now assigns the array/hash element if the accessor
835 is called with an array/hash element as the B<sole> argument.
839 Data::Dumper has now an option to sort hashes.
843 Data::Dumper has now an option to dump code references
848 DB_File now supports newer Berkeley DB versions, among
853 The English module can now be used without the infamous performance
856 use English '-no_performance_hit';
858 (Assuming, of course, that one doesn't need the troublesome variables
859 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
860 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
864 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
865 new-style constant dispatch section (see L<ExtUtils::Constant>).
866 This means that they will be more robust and hopefully faster.
870 File::Find now chdir()s correctly when chasing symbolic links.
874 File::Find now has pre- and post-processing callbacks. It also
875 correctly changes directories when chasing symbolic links. Callbacks
876 (naughtily) exiting with "next;" instead of "return;" now work.
880 File::Find is now (again) reentrant. It also has been made
885 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
886 prototype mismatch with CORE::glob().
890 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
891 the returned list of filenames.
895 Devel::Peek now has an interface for the Perl memory statistics
896 (this works only if you are using perl's malloc, and if you have
897 compiled with debugging).
901 IPC::Open3 now allows the use of numeric file descriptors.
905 IO::Socket has now atmark() method, which returns true if the socket
906 is positioned at the out-of-band mark. The method is also exportable
907 as a sockatmark() function.
911 IO::Socket::INET has support for ReusePort option (if your platform
912 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
913 you may want to prefer ReuseAddr.
917 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
918 that the operating system will make one up.)
922 use lib now works identically to @INC. Removing directories
923 with 'no lib' now works.
927 Math::BigFloat and Math::BigInt have undergone a full rewrite.
928 They are now magnitudes faster, and they support various
929 bignum libraries such as GMP and PARI as their backends.
933 Math::Complex handles inf, NaN etc., better.
937 Net::Ping has been enhanced. There is now "external" protocol which
938 uses Net::Ping::External module which runs external ping(1) and parses
939 the output. A version of Net::Ping::External is available in CPAN.
943 POSIX::sigaction() is now much more flexible and robust.
944 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
945 handlers, installing new handlers was not atomic.
949 In Safe the C<%INC> now localised in a Safe compartment so that
954 In SDBM_File on dosish platforms, some keys went missing because of
955 lack of support for files with "holes". A workaround for the problem
960 In Search::Dict one can now have a pre-processing hook for the
961 lines being searched.
965 The Shell module now has an OO interface.
969 The Test module has been significantly enhanced.
973 The vars pragma now supports declaring fully qualified variables.
974 (Something that C<our()> does not and will not support.)
978 The utf8:: name space (as in the pragma) provides various
979 Perl-callable functions to provide low level access to Perl's
980 internal Unicode representation. At the moment only length()
981 has been implemented.
985 =head1 Utility Changes
991 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
996 F<emacs/e2ctags.pl> is now much faster.
1000 C<h2ph> now supports C trigraphs.
1004 C<h2xs> now produces a template README.
1008 C<h2xs> now uses C<Devel::PPort> for better portability between
1009 different versions of Perl.
1013 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
1014 newly created extensions that define constants. Since the new code is
1015 more correct (if you have two constants where the first one is a
1016 prefix of the second one, the first constant B<never> gets defined),
1017 less lossy (it uses integers for integer constant, as opposed to the
1018 old code that used floating point numbers even for integer constants),
1019 and slightly faster, you might want to consider regenerating your
1020 extension code (the new scheme makes regenerating easy).
1021 L<h2xs> now also supports C trigraphs.
1025 C<libnetcfg> has been added to configure the libnet.
1029 C<perlbug> is now much more robust. It also sends the bug report to
1030 perl.org, not perl.com.
1034 C<perlcc> has been rewritten and its user interface (that is,
1035 command line) is much more like that of the UNIX C compiler, cc.
1036 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1040 C<perlivp> is a new Installation Verification Procedure utility
1041 for running any time after installing Perl.
1045 C<pod2html> now allows specifying a cache directory.
1049 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1050 implementation of sed in Perl: you can use the sed functionality by
1051 using the C<psed> utility.)
1055 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1059 C<xsubpp> now supports OUT keyword.
1063 =head1 New Documentation
1069 perl56delta details the changes between the 5.005 release and the
1074 perlclib documents the internal replacements for standard C library
1075 functions. (Interesting only for extension writers and Perl core
1080 perldebtut is a Perl debugging tutorial.
1084 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1088 perlintro is a gentle introduction to Perl.
1092 perliol documents the internals of PerlIO with layers.
1096 perlmodstyle is a style guide for writing modules.
1100 perlnewmod tells about writing and submitting a new module.
1104 perlpacktut is a pack() tutorial.
1108 perlpod has been rewritten to be clearer and to record the best
1109 practices gathered over the years.
1113 perlpodspec is a more formal specification of the pod format,
1114 mainly of interest for writers of pod applications, not to
1115 people writing in pod.
1119 perlretut is a regular expression tutorial.
1123 perlrequick is a regular expressions quick-start guide.
1124 Yes, much quicker than perlretut.
1128 perltodo has been updated.
1132 perltootc has been renamed as perltooc (to not to conflict
1133 with perltoot in filesystems restricted to "8.3" names)
1137 perluniintro is an introduction to using Unicode in Perl
1138 (perlunicode is more of a reference)
1142 perlutil explains the command line utilities packaged with the Perl
1147 The following platform-specific documents are available before
1148 the installation as README.I<platform>, and after the installation
1151 perlaix perlamiga perlapollo perlbeos perlbs2000
1152 perlce perlcygwin perldgux perldos perlepoc perlhpux
1153 perlhurd perlmachten perlmacos perlmint perlmpeix
1154 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1155 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1161 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1162 confusion with the Perl POSIX module.
1166 The documentation for the WinCE platform is called "CE", to avoid
1167 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1171 =head1 Performance Enhancements
1177 map() could get pathologically slow when the result list it generates
1178 is larger than the source list. The performance has been improved for
1183 sort() has been changed to use primarily mergesort internally as
1184 opposed to the earlier quicksort. For very small lists this may
1185 result in slightly slower sorting times, but in general the speedup
1186 should be at least 20%. Additional bonuses are that the worst case
1187 behaviour of sort() is now better (in computer science terms it now
1188 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1189 worst-case run time behaviour), and that sort() is now stable
1190 (meaning that elements with identical keys will stay ordered as they
1191 were before the sort). See the C<sort> pragma for information.
1193 The story in more detail: suppose you want to serve yourself a little
1196 @digits = ( 3,1,4,1,5,9 );
1198 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1199 Which C<1> comes first is hard to know, since one C<1> looks pretty
1200 much like any other. You can regard this as totally trivial,
1201 or somewhat profound. However, if you just want to sort the even
1202 digits ahead of the odd ones, then what will
1204 sort { ($a % 2) <=> ($b % 2) } @digits;
1206 yield? The only even digit, C<4>, will come first. But how about
1207 the odd numbers, which all compare equal? With the quicksort algorithm
1208 used to implement Perl 5.6 and earlier, the order of ties is left up
1209 to the sort. So, as you add more and more digits of Pi, the order
1210 in which the sorted even and odd digits appear will change.
1211 and, for sufficiently large slices of Pi, the quicksort algorithm
1212 in Perl 5.8 won't return the same results even if reinvoked with the
1213 same input. The justification for this rests with quicksort's
1214 worst case behavior. If you run
1216 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1218 (something you might approximate if you wanted to merge two sorted
1219 arrays using sort), doubling $N doesn't just double the quicksort time,
1220 it I<quadruples> it. Quicksort has a worst case run time that can
1221 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1222 on patterns that may well arise in normal use. You won't notice this
1223 for small arrays, but you I<will> notice it with larger arrays,
1224 and you may not live long enough for the sort to complete on arrays
1225 of a million elements. So the 5.8 quicksort scrambles large arrays
1226 before sorting them, as a statistical defence against quadratic behaviour.
1227 But that means if you sort the same large array twice, ties may be
1228 broken in different ways.
1230 Because of the unpredictability of tie-breaking order, and the quadratic
1231 worst-case behaviour, quicksort was I<almost> replaced completely with
1232 a stable mergesort. I<Stable> means that ties are broken to preserve
1233 the original order of appearance in the input array. So
1235 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1237 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1238 appear in the output in the same order they appeared in the input.
1239 Mergesort has worst case O(NlogN) behaviour, the best value
1240 attainable. And, ironically, this mergesort does particularly
1241 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1242 in O(N) time. But quicksort was rescued at the last moment because
1243 it is faster than mergesort on certain inputs and platforms.
1244 For example, if you really I<don't> care about the order of even
1245 and odd digits, quicksort will run in O(N) time; it's very good
1246 at sorting many repetitions of a small number of distinct elements.
1247 The quicksort divide and conquer strategy works well on platforms
1248 with relatively small, very fast, caches. Eventually, the problem gets
1249 whittled down to one that fits in the cache, from which point it
1250 benefits from the increased memory speed.
1252 Quicksort was rescued by implementing a sort pragma to control aspects
1253 of the sort. The B<stable> subpragma forces stable behaviour,
1254 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1255 subpragmas are heavy-handed ways to select the underlying implementation.
1256 The leading C<_> is a reminder that these subpragmas may not survive
1257 beyond 5.8. More appropriate mechanisms for selecting the implementation
1258 exist, but they wouldn't have arrived in time to save quicksort.
1262 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1263 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1264 reasonably fast while producing a much better spread of values than
1265 the old hashing algorithm (originally by Chris Torek, later tweaked by
1266 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1267 all 3-char printable ASCII keys comes much closer to passing the
1268 DIEHARD random number generation tests. According to perlbench, this
1269 change has not affected the overall speed of Perl.
1273 unshift() should now be noticeably faster.
1277 =head1 Installation and Configuration Improvements
1279 =head2 Generic Improvements
1285 INSTALL now explains how you can configure Perl to use 64-bit
1286 integers even on non-64-bit platforms.
1290 Policy.sh policy change: if you are reusing a Policy.sh file
1291 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1292 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1293 them will now be changed to the new prefix, /foo/bar. (Previously
1294 only $prefix changed.) If you do not like this new behaviour,
1295 specify prefix, siteprefix, and vendorprefix explicitly.
1299 A new optional location for Perl libraries, otherlibdirs, is available.
1300 It can be used for example for vendor add-ons without disturbing Perl's
1301 own library directories.
1305 In many platforms the vendor-supplied 'cc' is too stripped-down to
1306 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1307 to be the case and 'cc' does not seem to be the GNU C compiler
1308 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1312 gcc needs to closely track the operating system release to avoid
1313 build problems. If Configure finds that gcc was built for a different
1314 operating system release than is running, it now gives a clearly visible
1315 warning that there may be trouble ahead.
1319 If binary compatibility with the 5.005 release is not wanted, Configure
1320 no longer suggests including the 5.005 modules in @INC.
1324 Configure C<-S> can now run non-interactively.
1328 Configure support for pdp11-style memory models has been removed due
1333 configure.gnu now works with options with whitespace in them.
1337 installperl now outputs everything to STDERR.
1341 $Config{byteorder} is now computed dynamically (this is more robust
1342 with "fat binaries" where an executable image contains binaries for
1343 more than one binary platform.)
1347 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1348 get appended to the $Config{archname} (also known as $^O) anymore.
1349 Instead, if you explicitly choose not to use perlio (Configure command
1350 line option -Uuseperlio), you will get "-stdio" appended.
1354 Another change related to the architecture name is that "-64all"
1355 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1356 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1360 In AFS installations one can configure the root of the AFS to be
1361 somewhere else than the default F</afs> by using the Configure
1362 parameter C<-Dafsroot=/some/where/else>.
1366 APPLLIB_EXP, a less-know configuration-time definition, has been
1367 documented. It can be used to prepend site-specific directories
1368 to Perl's default search path (@INC), see INSTALL for information.
1372 The version of Berkeley DB used when the Perl (and, presumably, the
1373 DB_File extension) was built is now available as
1374 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1375 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1376 DB_VERSION_PATCH_CFG> from C.
1380 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1381 has been documented in INSTALL.
1385 If you have CPAN access (either network or a local copy such as a
1386 CD-ROM) you can during specify extra modules to Configure to build and
1387 install with Perl using the -Dextras=... option. See INSTALL for
1392 In addition to config.over a new override file, config.arch, is
1393 available. That is supposed to be used by hints file writers for
1394 architecture-wide changes (as opposed to config.over which is for
1399 If your file system supports symbolic links you can build Perl outside
1400 of the source directory by
1402 mkdir /tmp/perl/build/directory
1403 cd /tmp/perl/build/directory
1404 sh /path/to/perl/source/Configure -Dmksymlinks ...
1406 This will create in /tmp/perl/build/directory a tree of symbolic links
1407 pointing to files in /path/to/perl/source. The original files are left
1408 unaffected. After Configure has finished you can just say
1412 and Perl will be built and tested, all in /tmp/perl/build/directory.
1416 For Perl developers several new make targets for profiling
1417 and debugging have been added, see L<perlhack>.
1423 Use of the F<gprof> tool to profile Perl has been documented in
1424 L<perlhack>. There is a make target called "perl.gprof" for
1425 generating a gprofiled Perl executable.
1429 If you have GCC 3, there is a make target called "perl.gcov" for
1430 creating a gcoved Perl executable for coverage analysis. See
1435 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1436 have been added, see L<perlhack> for more information about pixie and
1443 Guidelines of how to construct minimal Perl installations have
1444 been added to INSTALL.
1448 The Thread extension is now not built at all under ithreads
1449 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1450 Thread extension requires being Configured with C<-Duse5005threads>).
1452 But note that the Thread.pm interface is now shared by both
1457 =head2 New Or Improved Platforms
1459 For the list of platforms known to support Perl,
1460 see L<perlport/"Supported Platforms">.
1466 AIX dynamic loading should be now better supported.
1470 AIX should now work better with gcc, threads, and 64-bitness. Also the
1471 long doubles support in AIX should be better now. See L<perlaix>.
1475 After a long pause, AmigaOS has been verified to be happy with Perl.
1479 AtheOS (http://www.atheos.cx/) is a new platform.
1483 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1487 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1491 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1492 have been regained. Many test suite tests still fail and the
1493 co-existence of Unicode and EBCDIC isn't quite settled, but the
1494 situation is much better than with Perl 5.6. See L<perlos390>,
1495 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1499 Building perl with -Duseithreads or -Duse5005threads now works under
1500 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1501 need a thread library package installed. See README.hpux.
1505 MacOS Classic (MacPerl has of course been available since
1506 perl 5.004 but now the source code bases of standard Perl
1507 and MacPerl have been synchronised)
1511 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1512 filesystems. (The case-insensitivity confused the Perl build process.)
1516 NCR MP-RAS is now supported.
1520 NetWare from Novell is now supported. See L<perlnetware>.
1524 NonStop-UX is now supported.
1528 NEC SUPER-UX is now supported.
1532 Amdahl UTS UNIX mainframe platform is now supported.
1536 WinCE is now supported. See L<perlce>.
1540 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1541 support for dynamic loading. This is not selected by default,
1542 however, you must specify -Dusedl in the arguments of Configure.
1546 =head1 Selected Bug Fixes
1548 Numerous memory leaks and uninitialized memory accesses have been
1549 hunted down. Most importantly anonymous subs used to leak quite
1556 The autouse pragma didn't work for Multi::Part::Function::Names.
1560 caller() could cause core dumps in certain situations. Carp was sometimes
1561 affected by this problem.
1565 chop(@list) in list context returned the characters chopped in
1566 reverse order. This has been reversed to be in the right order.
1570 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1571 when building the Perl binary. The only exception to this is SunOS 4.x,
1576 The behaviour of non-decimal but numeric string constants such as
1577 "0x23" was platform-dependent: in some platforms that was seen as 35,
1578 in some as 0, in some as a floating point number (don't ask). This
1579 was caused by Perl using the operating system libraries in a situation
1580 where the result of the string to number conversion is undefined: now
1581 Perl consistently handles such strings as zero in numeric contexts.
1585 The order of DESTROYs has been made more predictable.
1589 Several debugger fixes: exit code now reflects the script exit code,
1590 condition C<"0"> now treated correctly, the C<d> command now checks
1591 line number, the C<$.> no longer gets corrupted, all debugger output
1592 now goes correctly to the socket if RemotePort is set.
1596 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1597 when statically building extensions into perl. This has been corrected.
1601 L<dprofpp> -R didn't work.
1605 C<*foo{FORMAT}> now works.
1608 Infinity is now recognized as a number.
1612 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1613 the Tk extension with 5.6.0.)
1617 Lexicals I: lexicals outside an eval "" weren't resolved
1618 correctly inside a subroutine definition inside the eval "" if they
1619 were not already referenced in the top level of the eval""ed code.
1623 Lexicals II: lexicals leaked at file scope into subroutines that
1624 were declared before the lexicals.
1628 Lexical warnings now propagating correctly between scopes
1629 and into C<eval "...">.
1633 C<use warnings qw(FATAL all)> did not work as intended. This has been
1638 warnings::enabled() now reports the state of $^W correctly if the caller
1639 isn't using lexical warnings.
1643 Line renumbering with eval and C<#line> now works.
1647 Fixed numerous memory leaks, especially in eval "".
1651 mkdir() now ignores trailing slashes in the directory name,
1652 as mandated by POSIX.
1656 Some versions of glibc have a broken modfl(). This affects builds
1657 with C<-Duselongdouble>. This version of Perl detects this brokenness
1658 and has a workaround for it. The glibc release 2.2.2 is known to have
1659 fixed the modfl() bug.
1663 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1664 return 27406, instead of 27047).
1668 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1669 more compatible with 5.005. Infinity is now recognised as a number.
1673 Numeric conversions did not recognize changes in the string value
1674 properly in certain circumstances.
1678 Attributes (like :shared) didn't work with our().
1682 our() variables will not cause "will not stay shared" warnings.
1686 "our" variables of the same name declared in two sibling blocks
1687 resulted in bogus warnings about "redeclaration" of the variables.
1688 The problem has been corrected.
1692 pack "Z" now correctly terminates the string with "\0".
1696 Fix password routines which in some shadow password platforms
1697 (e.g. HP-UX) caused getpwent() to return every other entry.
1701 The PERL5OPT environment variable (for passing command line arguments
1702 to Perl) didn't work for more than a single group of options.
1706 PERL5OPT with embedded spaces didn't work.
1710 printf() no longer resets the numeric locale to "C".
1714 C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1718 pos() did not return the correct value within s///ge in earlier
1719 versions. This is now handled correctly.
1723 Printing quads (64-bit integers) with printf/sprintf now works
1724 without the q L ll prefixes (assuming you are on a quad-capable platform).
1728 Regular expressions on references and overloaded scalars now work.
1732 Right-hand side magic (GMAGIC) could in many cases such as string
1733 concatenation be invoked too many times.
1737 scalar() now forces scalar context even when used in void context.
1741 SOCKS support is now much more robust.
1745 sort() arguments are now compiled in the right wantarray context
1746 (they were accidentally using the context of the sort() itself).
1747 The comparison block is now run in scalar context, and the arguments
1748 to be sorted are always provided list context.
1752 Changed the POSIX character class C<[[:space:]]> to include the (very
1753 rarely used) vertical tab character. Added a new POSIX-ish character
1754 class C<[[:blank:]]> which stands for horizontal whitespace
1755 (currently, the space and the tab).
1759 The tainting behaviour of sprintf() has been rationalized. It does
1760 not taint the result of floating point formats anymore, making the
1761 behaviour consistent with that of string interpolation.
1765 Some cases of inconsistent taint propagation (such as within hash
1766 values) have been fixed.
1770 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1771 of simple pattern matches. These are now handled better.
1775 Regular expression debug output (whether through C<use re 'debug'>
1776 or via C<-Dr>) now looks better.
1780 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
1785 Use of $& could trigger a core dump under some situations. This
1790 The regular expression captured submatches ($1, $2, ...) are now
1791 more consistently unset if the match fails, instead of leaving false
1792 data lying around in them.
1796 readline() on files opened in "slurp" mode could return an extra "" at
1797 the end in certain situations. This has been corrected.
1801 Autovivification of symbolic references of special variables described
1802 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
1807 Sys::Syslog ignored the C<LOG_AUTH> constant.
1811 All but the first argument of the IO syswrite() method are now optional.
1815 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1816 in multiple threads simultaneously are now thread-safe.
1820 Tie::ARRAY SPLICE method was broken.
1824 Allow read-only string on left hand side of non-modifying tr///.
1828 Several Unicode fixes.
1834 BOMs (byte order marks) in the beginning of Perl files
1835 (scripts, modules) should now be transparently skipped.
1836 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1840 The character tables have been updated to Unicode 3.1.1.
1844 Comparing with utf8 data does not magically upgrade non-utf8 data
1849 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1853 Concatenation with the C<.> operator or via variable interpolation,
1854 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1855 substitution with C<s///>, single-quoted UTF8, should now work.
1859 The C<tr///> operator now works. Note that the C<tr///CU>
1860 functionality has been removed (but see pack('U0', ...)).
1864 C<eval "v200"> now works.
1868 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
1869 This has been corrected.
1873 Zero entries were missing from the Unicode classes like C<IsDigit>.
1879 Large unsigned numbers (those above 2**31) could sometimes lose their
1880 unsignedness, causing bogus results in arithmetic operations.
1884 =head2 Platform Specific Changes and Fixes
1892 Perl now works on post-4.0 BSD/OSes.
1898 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
1904 Numerous updates; currently synchronised with Cygwin 1.1.4.
1908 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1914 EPOC update after Perl 5.6.0. See README.epoc.
1920 Perl now works on post-3.0 FreeBSDs.
1926 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1932 Numerous compilation flag and hint enhancements; accidental mixing
1933 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1943 Long doubles should now work (see INSTALL).
1947 Linux previously had problems related to sockaddrlen when using
1948 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1956 Compilation of the standard Perl distribution in MacOS Classic should
1957 now work if you have the Metrowerks development environment and
1958 the missing Mac-specific toolkit bits. Contact the macperl mailing
1965 MPE/iX update after Perl 5.6.0. See README.mpeix.
1971 Perl now works on NetBSD/sparc.
1977 Now works with usethreads (see INSTALL).
1983 64-bitness using the Sun Workshop compiler now works.
1987 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1989 The operating system version letter now recorded in $Config{osvers}.
1990 Allow compiling with gcc (previously explicitly forbidden). Compiling
1991 with gcc still not recommended because buggy code results, even with
1998 Fixed various alignment problems that lead into core dumps either
1999 during build or later; no longer dies on math errors at runtime;
2000 now using full quad integers (64 bits), previously was using
2001 only 46 bit integers for speed.
2007 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2008 (see INSTALL); now works with Perl's malloc.
2010 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2011 unimplemented. It now works as documented.
2013 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2014 was that a pid of -1 would cause a wildcard search of all processes on
2015 the system. The most significant enhancement is that we can now
2016 usually get the completion status of a terminated process.
2018 POSIX-style signals are now emulated much better on VMS versions prior
2021 The C<system> function and backticks operator have improved
2022 functionality and better error handling.
2032 accept() no longer leaks memory.
2036 Borland C++ v5.5 is now a supported compiler that can build Perl.
2037 However, the generated binaries continue to be incompatible with those
2038 generated by the other supported compilers (GCC and Visual C++).
2042 Better chdir() return value for a non-existent directory.
2046 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2050 New %ENV entries now propagate to subprocesses.
2054 Current directory entries in %ENV are now correctly propagated to child
2059 $ENV{LIB} now used to search for libs under Visual C.
2063 fork() emulation has been improved in various ways, but still continues
2064 to be experimental. See L<perlfork> for known bugs and caveats.
2068 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2072 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2073 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2077 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2081 The makefiles now provide a single switch to bulk-enable all the features
2082 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2086 Allow REG_EXPAND_SZ keys in the registry.
2090 Can now send() from all threads, not just the first one.
2094 Fake signal handling reenabled, bugs and all.
2098 %SIG has been enabled under USE_ITHREADS, but its use is completely
2099 unsupported under all configurations.
2103 Less stack reserved per thread so that more threads can run
2104 concurrently. (Still 16M per thread.)
2108 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
2109 (works better when perl is running as service).
2113 Better UNC path handling under ithreads.
2117 wait(), waitpid() and backticks now return the correct exit status under
2122 winsock handle leak fixed.
2128 =head1 New or Changed Diagnostics
2134 All regular expression compilation error messages are now hopefully
2135 easier to understand both because the error message now comes before
2136 the failed regex and because the point of failure is now clearly
2137 marked by a C<E<lt>-- HERE> marker.
2141 The various "opened only for", "on closed", "never opened" warnings
2142 drop the C<main::> prefix for filehandles in the C<main> package,
2143 for example C<STDIN> instead of C<main::STDIN>.
2147 The "Unrecognized escape" warning has been extended to include C<\8>,
2148 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2152 Two new debugging options have been added: if you have compiled your
2153 Perl with debugging, you can use the -DT and -DR options to trace
2154 tokenising and to add reference counts to displaying variables,
2159 If an attempt to use a (non-blessed) reference as an array index
2160 is made, a warning is given.
2164 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2165 now give a warning. This may be a problem for generated and evaled
2170 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2171 using the C<"C"> format you will get an optional warning. Similarly
2172 for the C<"c"> format and a number less than -128 or more than 127.
2176 Certain regex modifiers such as C<(?o)> make sense only if applied to
2177 the entire regex. You will an optional warning if you try to do otherwise.
2181 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2182 has been deprecated for a while. Now you will get an optional warning.
2186 =head1 Changed Internals
2192 perlapi.pod (a companion to perlguts) now attempts to document the
2197 You can now build a really minimal perl called microperl.
2198 Building microperl does not require even running Configure;
2199 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2200 many assumptions, some of which may be too bold; the resulting
2201 executable may crash or otherwise misbehave in wondrous ways.
2202 For careful hackers only.
2206 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2207 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2208 interfaces to the publicised API. For the full list of the available
2209 APIs see L<perlapi>.
2213 Made possible to propagate customised exceptions via croak()ing.
2217 Now xsubs can have attributes just like subs. (Well, at least the
2218 built-in attributes.)
2222 dTHR and djSP have been obsoleted; the former removed (because it's
2223 a no-op) and the latter replaced with dSP.
2227 PERL_OBJECT has been completely removed.
2231 The MAGIC constants (e.g. C<'P'>) have been macrofied
2232 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2233 and maintainability.
2237 The regex compiler now maintains a structure that identifies nodes in
2238 the compiled bytecode with the corresponding syntactic features of the
2239 original regex expression. The information is attached to the new
2240 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2241 complete information.
2245 The C code has been made much more C<gcc -Wall> clean. Some warning
2246 messages still remain in some platforms, so if you are compiling with
2247 gcc you may see some warnings about dubious practices. The warnings
2248 are being worked on.
2252 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2256 Documentation on how to use the Perl source repository has been added
2257 to F<Porting/repository.pod>.
2261 There are now several profiling make targets.
2265 =head1 Security Vulnerability Closed
2267 (This change was already made in 5.7.0 but bears repeating here.)
2269 A potential security vulnerability in the optional suidperl component
2270 of Perl was identified in August 2000. suidperl is neither built nor
2271 installed by default. As of November 2001 the only known vulnerable
2272 platform is Linux, most likely all Linux distributions. CERT and
2273 various vendors and distributors have been alerted about the vulnerability.
2274 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2275 for more information.
2277 The problem was caused by Perl trying to report a suspected security
2278 exploit attempt using an external program, /bin/mail. On Linux
2279 platforms the /bin/mail program had an undocumented feature which
2280 when combined with suidperl gave access to a root shell, resulting in
2281 a serious compromise instead of reporting the exploit attempt. If you
2282 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2283 suidperl is not installed, you are safe.
2285 The exploit attempt reporting feature has been completely removed from
2286 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2287 from all the Perl 5.7 releases), so that particular vulnerability
2288 isn't there anymore. However, further security vulnerabilities are,
2289 unfortunately, always possible. The suidperl functionality is most
2290 probably going to be removed in Perl 5.10. In any case, suidperl
2291 should only be used by security experts who know exactly what they are
2292 doing and why they are using suidperl instead of some other solution
2293 such as sudo (see http://www.courtesan.com/sudo/).
2297 Several new tests have been added, especially for the F<lib>
2298 subsection. There are now about 34 000 individual tests (spread over
2299 about 530 test scripts), in the regression suite (5.6.1 has about
2300 11700 tests, in 258 test scripts) Many of the new tests are introduced
2301 by the new modules, but still in general Perl is now more thoroughly
2304 Because of the large number of tests, running the regression suite
2305 will take considerably longer time than it used to: expect the suite
2306 to take up to 4-5 times longer to run than in perl 5.6. In a really
2307 fast machine you can hope to finish the suite in about 5 minutes
2310 The tests are now reported in a different order than in earlier Perls.
2311 (This happens because the test scripts from under t/lib have been moved
2312 to be closer to the library/extension they are testing.)
2314 =head1 Known Problems
2322 In AIX 4.2 Perl extensions that use C++ functions that use statics
2323 may have problems in that the statics are not getting initialized.
2324 In newer AIX releases this has been solved by linking Perl with
2325 the libC_r library, but unfortunately in AIX 4.2 the said library
2326 has an obscure bug where the various functions related to time
2327 (such as time() and gettimeofday()) return broken values, and
2328 therefore in AIX 4.2 Perl is not linked against the libC_r.
2332 vac 5.0.0.0 May Produce Buggy Code For Perl
2334 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2335 resulting in few random tests failing, but when the failing tests
2336 are run by hand, they succeed. We suggest upgrading to at least
2337 vac version 5.0.1.0, that has been known to compile Perl correctly.
2338 "lslpp -L|grep vac.C" will tell you the vac version.
2342 =head2 Amiga Perl Invoking Mystery
2344 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2345 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2346 known but the current suspect is the F<ixemul> library.
2348 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2350 Don't panic. Read INSTALL 'make test' section instead.
2352 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2354 The subtests 11 and 12 sometimes fail and sometimes work.
2356 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2358 The lib/io_multihomed test may hang in HP-UX if Perl has been
2359 configured to be 64-bit. Because other 64-bit platforms do not hang in
2360 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2361 test attempts to create and connect to "multihomed" sockets (sockets
2362 which have multiple IP addresses).
2364 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2366 If perl is configured with -Duse64bitall, the successful result of the
2367 subtest 10 of lib/posix may arrive before the successful result of the
2368 subtest 9, which confuses the test harness so much that it thinks the
2371 =head2 Linux With Sfio Fails op/misc Test 48
2377 The following tests are known to fail:
2379 Failed Test Stat Wstat Total Fail Failed List of Failed
2380 -------------------------------------------------------------------------
2381 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2382 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2383 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2384 ../lib/warnings.t 450 1 0.22% 316
2388 OS/390 has rather many test failures but the situation is actually
2389 better than it was in 5.6.0, it's just that so many new modules and
2390 tests have been added.
2392 Failed Test Stat Wstat Total Fail Failed List of Failed
2393 -----------------------------------------------------------------------------
2394 ../ext/B/Deparse.t 14 1 7.14% 14
2395 ../ext/B/Showlex.t 1 1 100.00% 1
2396 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2398 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2399 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2400 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2401 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2402 ../lib/warnings.t 434 1 0.23% 75
2403 ../lib/ExtUtils.t 27 1 3.70% 25
2404 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2405 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2406 ../lib/User/pwent.t 9 1 11.11% 4
2407 op/pat.t 660 6 0.91% 242-243 424-425
2409 op/split.t 0 9 ?? ?? % ??
2410 op/taint.t 174 3 1.72% 156 162 168
2411 op/tr.t 70 3 4.29% 50 58-59
2412 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2414 =head2 op/sprintf tests 129 and 130
2416 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2417 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2418 The failing platforms do not comply with the ANSI C Standard, line
2419 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2420 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2421 the printf format "%.0f", most often they produce "0" and "-0".)
2423 =head2 Failure of Thread tests
2425 B<Note that support for 5.005-style threading remains experimental
2426 and practically unsupported.>
2428 The following tests are known to fail due to fundamental problems in
2429 the 5.005 threading implementation. These are not new failures--Perl
2430 5.005_0x has the same bugs, but didn't have these tests.
2432 ext/List/Util/t/first 2
2434 ext/Thread/thr5005 19-20
2436 These failures are unlikely to get fixed.
2444 ext/POSIX/sigaction subtests 6 and 13 may fail.
2448 lib/ExtUtils may spuriously claim that subtest 28 failed,
2449 which is interesting since the test only has 27 tests.
2453 Numerous numerical test failures
2455 op/numconvert 209,210,217,218
2457 ext/Time/HiRes/HiRes 9
2458 lib/Math/BigInt/t/bigintpm 1145
2461 These tests fail because of yet unresolved floating point inaccuracies.
2467 There are a few known test failures, see L<perluts>.
2471 There is one known test failure with a default configuration:
2473 [.run]switches..........................FAILED on test 1
2477 In multi-CPU boxes there are some problems with the I/O buffering:
2478 some output may appear twice.
2480 =head2 Localising a Tied Variable Leaks Memory
2483 tie my %tie_hash => 'Tie::StdHash';
2487 local($tie_hash{Foo}) = 1; # leaks
2489 Code like the above is known to leak memory every time the local()
2492 =head2 Localising Tied Arrays and Hashes Is Broken
2496 doesn't work as one would expect: the old value is restored
2499 =head2 Self-tying of Arrays and Hashes Is Forbidden
2501 Self-tying of arrays and hashes is broken in rather deep and
2502 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2503 frustrated at the mysterious results (core dumps, most often) it is
2504 for now forbidden (you will get a fatal error even from an attempt).
2506 =head2 Building Extensions Can Fail Because Of Largefiles
2508 Some extensions like mod_perl are known to have issues with
2509 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2510 default to 64 bits wide, where supported. Modules may fail to compile
2511 at all or compile and work incorrectly. Currently there is no good
2512 solution for the problem, but Configure now provides appropriate
2513 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2514 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2515 having problems can try configuring themselves without the
2516 largefileness. This is admittedly not a clean solution, and the
2517 solution may not even work at all. One potential failure is whether
2518 one can (or, if one can, whether it's a good idea) link together at
2519 all binaries with different ideas about file offsets, all this is
2522 =head2 Unicode Support on EBCDIC Still Spotty
2524 Though mostly working, Unicode support still has problem spots on
2525 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2526 regular expression constructs for code points less than 256: the
2527 pP are testing for Unicode code points, not knowing about EBCDIC.
2529 =head2 The Compiler Suite Is Still Experimental
2531 The compiler suite is slowly getting better but it continues to be
2532 highly experimental. Use in production environments is discouraged.
2534 =head2 The Long Double Support Is Still Experimental
2536 The ability to configure Perl's numbers to use "long doubles",
2537 floating point numbers of hopefully better accuracy, is still
2538 experimental. The implementations of long doubles are not yet
2539 widespread and the existing implementations are not quite mature
2540 or standardised, therefore trying to support them is a rare
2541 and moving target. The gain of more precision may also be offset
2542 by slowdown in computations (more bits to move around, and the
2543 operations are more likely to be executed by less optimised
2546 =head2 Seen In Perl 5.7 But Gone Now
2548 Some modules were seen in the Perl 5.7 development releases
2549 but are not present in 5.8.0.
2555 C<Attribute::Handlers> was removed because the implementation of C<my>
2556 variable attributes changed so much that the Attribute::Handlers will
2557 require a major rewrite. (This means that you can't use
2558 Attribute::Handler 0.76 with Perl 5.8.0.)
2562 C<Time::Piece> (previously known as C<Time::Object>) was removed
2563 because it was felt that it didn't have enough value in it to be a
2564 core module. It is still a useful module, though, and is available
2569 =head1 Reporting Bugs
2571 If you find what you think is a bug, you might check the articles
2572 recently posted to the comp.lang.perl.misc newsgroup and the perl
2573 bug database at http://bugs.perl.org. There may also be
2574 information at http://www.perl.com/perl/, the Perl Home Page.
2576 If you believe you have an unreported bug, please run the B<perlbug>
2577 program included with your release. Be sure to trim your bug down
2578 to a tiny but sufficient test case. Your bug report, along with the
2579 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2580 analysed by the Perl porting team.
2584 The F<Changes> file for exhaustive details on what changed.
2586 The F<INSTALL> file for how to build Perl.
2588 The F<README> file for general stuff.
2590 The F<Artistic> and F<Copying> files for copyright information.
2594 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.