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 releaes.
76 =head2 Socket Extension Dynamic in VMS
78 The Socket extension is now dynamically loaded instead of being
79 statically built in. This may or may not be a problem with ancient
80 TCP/IP stacks of VMS: we do not know since we weren't able to test
81 Perl in such configurations.
83 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
85 Perl now uses IEEE format (T_FLOAT) as the default internal floating
86 point format on OpenVMS Alpha, potentially breaking binary compatibility
87 with external libraries or existing data. G_FLOAT is still available as
88 a configuration option. The default on VAX (D_FLOAT) has not changed.
90 =head2 Different Definition of the Unicode Character Classes \p{In...}
92 As suggested by the Unicode consortium, the Unicode character classes
93 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
94 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
95 constructs are used. This has changed the definition of some of those
98 The difference between scripts and blocks is that scripts are the
99 glyphs used by a language or a group of languages, while the blocks
100 are more artificial groupings of 256 characters based on the Unicode
103 In general this change results in more inclusive Unicode character
104 classes, but changes to the other direction also do take place:
105 for example while the script C<Latin> includes all the Latin
106 characters and their various diacritic-adorned versions, it
107 does not include the various punctuation or digits (since they
108 are not solely C<Latin>).
110 Changes in the character class semantics may have happened if a script
111 and a block happen to have the same name, for example C<Hebrew>.
112 In such cases the script wins and C<\p{InHebrew}> now means the script
113 definition of Hebrew. The block definition in still available,
114 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
115 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
116 of affected character classes, see L<perlunicode/Blocks>.
118 =head2 Perl Parser Stress Tested
120 The Perl parser has been stress tested using both random input and
121 Markov chain input and the few found crashes and lockups have been
124 =head2 REF(...) Instead Of SCALAR(...)
126 A reference to a reference now stringifies as "REF(0x81485ec)" instead
127 of "SCALAR(0x81485ec)" in order to be more consistent with the return
136 The semantics of bless(REF, REF) were unclear and until someone proves
137 it to make some sense, it is forbidden.
141 The obsolete chat2 library that should never have been allowed
142 to escape the laboratory has been decommissioned.
146 The very dusty examples in the eg/ directory have been removed.
147 Suggestions for new shiny examples welcome but the main issue is that
148 the examples need to be documented, tested and (most importantly)
153 The (bogus) escape sequences \8 and \9 now give an optional warning
154 ("Unrecognized escape passed through"). There is no need to \-escape
159 The list of filenames from glob() (or <...>) is now by default sorted
160 alphabetically to be csh-compliant (which is what happened before
161 in most UNIX platforms). (bsd_glob() does still sort platform
162 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
166 Spurious syntax errors generated in certain situations, when glob()
167 caused File::Glob to be loaded for the first time, have been fixed.
171 Although "you shouldn't do that", it was possible to write code that
172 depends on Perl's hashed key order (Data::Dumper does this). The new
173 algorithm "One-at-a-Time" produces a different hashed key order.
174 More details are in L</"Performance Enhancements">.
178 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
179 In future releases this may become a fatal error.
183 The C<package;> syntax (C<package> without an argument) has been
184 deprecated. Its semantics were never that clear and its
185 implementation even less so. If you have used that feature to
186 disallow all but fully qualified variables, C<use strict;> instead.
190 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
191 recognised but now cause fatal errors. The previous behaviour of
192 ignoring them by default and warning if requested was unacceptable
193 since it, in a way, falsely promised that the features could be used.
197 The current user-visible implementation of pseudo-hashes (the weird
198 use of the first array element) is deprecated starting from Perl 5.8.0
199 and will be removed in Perl 5.10.0, and the feature will be
200 implemented differently. Not only is the current interface rather
201 ugly, but the current implementation slows down normal array and hash
202 use quite noticeably. The C<fields> pragma interface will remain
207 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
211 After years of trying the suidperl is considered to be too complex to
212 ever be considered truly secure. The suidperl functionality is likely
213 to be removed in a future release.
217 The long deprecated uppercase aliases for the string comparison
218 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
222 The tr///C and tr///U features have been removed and will not return;
223 the interface was a mistake. Sorry about that. For similar
224 functionality, see pack('U0', ...) and pack('C0', ...).
228 =head1 Core Enhancements
230 =head2 PerlIO is Now The Default
236 IO is now by default done via PerlIO rather than system's "stdio".
237 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
238 handle's behaviour. Layers can be specified at open time via 3-arg
241 open($fh,'>:crlf :utf8', $path) || ...
243 or on already opened handles via extended C<binmode>:
245 binmode($fh,':encoding(iso-8859-7)');
247 The built-in layers are: unix (low level read/write), stdio (as in
248 previous Perls), perlio (re-implementation of stdio buffering in a
249 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
250 but available on any platform). A mmap layer may be available if
251 platform supports it (mostly UNIXes).
253 Layers to be applied by default may be specified via the 'open' pragma.
255 See L</"Installation and Configuration Improvements"> for the effects
256 of PerlIO on your architecture name.
260 File handles can be marked as accepting Perl's internal encoding of Unicode
261 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
263 open($fh,">:utf8","Uni.txt");
265 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
266 for you since it's not UTF-8 what you will be getting but instead
267 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
268 http://www.unicode.org/unicode/reports/tr16/ for more information.
269 In future releases this naming may change.
273 File handles can translate character encodings from/to Perl's internal
274 Unicode form on read/write via the ":encoding()" layer.
278 File handles can be opened to "in memory" files held in Perl scalars via:
280 open($fh,'>', \$variable) || ...
284 Anonymous temporary files are available without need to
285 'use FileHandle' or other module via
287 open($fh,"+>", undef) || ...
289 That is a literal undef, not an undefined value.
293 The list form of C<open> is now implemented for pipes (at least on UNIX):
295 open($fh,"-|", 'cat', '/etc/motd')
297 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
302 =head2 Signals Are Now Safe
304 Perl used to be fragile in that signals arriving at inopportune moments
305 could corrupt Perl's internal state. Now Perl postpones handling of
306 signals until it's safe.
308 =head2 Unicode Overhaul
310 Unicode in general should be now much more usable than in Perl 5.6.0
311 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
312 regular expressions should work now, Unicode in tr/// should work now,
313 Unicode in I/O should work now.
319 The Unicode Character Database coming with Perl has been upgraded
320 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
324 For developers interested in enhancing Perl's Unicode capabilities:
325 almost all the UCD files are included with the Perl distribution in
326 the lib/unicore subdirectory. The most notable omission, for space
327 considerations, is the Unihan database.
331 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
332 added. "Blank" is like C isblank(), that is, it contains only
333 "horizontal whitespace" (the space character is, the newline isn't),
334 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
335 isn't, since that includes the vertical tabulator character, whereas
340 =head2 Understanding of Numbers
342 In general a lot of fixing has happened in the area of Perl's
343 understanding of numbers, both integer and floating point. Since in
344 many systems the standard number parsing functions like C<strtoul()>
345 and C<atof()> seem to have bugs, Perl tries to work around their
346 deficiencies. This results hopefully in more accurate numbers.
348 Perl now tries internally to use integer values in numeric conversions
349 and basic arithmetics (+ - * /) if the arguments are integers, and
350 tries also to keep the results stored internally as integers.
351 This change leads to often slightly faster and always less lossy
352 arithmetics. (Previously Perl always preferred floating point numbers
355 =head2 Miscellaneous Enhancements
361 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
362 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
366 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
367 in multiple arguments.)
371 END blocks are now run even if you exit/die in a BEGIN block.
372 Internally, the execution of END blocks is now controlled by
373 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
374 behaviour for Perl embedders. This will default in 5.10. See
379 Formats now support zero-padded decimal fields.
383 Lvalue subroutines can now return C<undef> in list context.
384 However, the lvalue subroutine feature still remains experimental.
388 A new special regular expression variable has been introduced:
389 C<$^N>, which contains the most-recently closed group (submatch).
393 C<no Module;> now works even if there is no "sub unimport" in the Module.
397 The numerical comparison operators return C<undef> if either operand
398 is a NaN. Previously the behaviour was unspecified.
402 The following builtin functions are now overridable: each(), keys(),
403 pop(), push(), shift(), splice(), unshift().
407 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
411 my __PACKAGE__ $obj now works.
415 The printf() and sprintf() now support parameter reordering using the
416 C<%\d+\$> and C<*\d+\$> syntaxes. For example
418 print "%2\$s %1\$s\n", "foo", "bar";
420 will print "bar foo\n". This feature helps in writing
421 internationalised software, and in general when the order
422 of the parameters can vary.
426 prototype(\&) is now available.
430 prototype(\[$@%&]) is now available to implicitly create references
431 (useful for example if you want to emulate the tie() interface).
435 untie() will now call an UNTIE() hook if it exists. See L<perltie>
440 L<utime> now supports C<utime undef, undef, @files> to change the
441 file timestamps to the current time.
445 The rules for allowing underscores (underbars) in numeric constants
446 have been relaxed and simplified: now you can have an underscore
447 simply B<between digits>.
451 =head1 Modules and Pragmata
453 =head2 New Modules and Pragmata
459 B<B::Concise> is a new compiler backend for walking the Perl syntax
460 tree, printing concise info about ops, from Stephen McCamant. The
461 output is highly customisable. See L<B::Concise>.
465 C<Class::ISA> for reporting the search path for a class's ISA tree,
466 by Sean Burke, has been added. See L<Class::ISA>.
470 C<Cwd> has now a split personality: if possible, an XS extension is
471 used, (this will hopefully be faster, more secure, and more robust)
472 but if not possible, the familiar Perl implementation is used.
476 C<Devel::PPPort>, originally from Kenneth Albanowski and now
477 maintained by Paul Marquess, has been added. It is primarily used
478 by C<h2xs> to enhance portability of of XS modules between different
483 C<Digest>, frontend module for calculating digests (checksums), from
484 Gisle Aas, has been added. See L<Digest>.
488 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
489 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
491 use Digest::MD5 'md5_hex';
493 $digest = md5_hex("Thirsty Camel");
495 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
497 NOTE: the C<MD5> backward compatibility module is deliberately not
498 included since its further use is discouraged.
502 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
503 between different character encodings. Support for Unicode,
504 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
505 compiled in to the module. Several other encodings (like Japanese,
506 Chinese, and MacIntosh encodings) are included and will be loaded at
507 runtime. See L<Encode>.
509 Any encoding supported by Encode module is also available to the
510 ":encoding()" layer if PerlIO is used.
514 C<I18N::Langinfo> can be use to query locale information.
515 See L<I18N::Langinfo>.
519 C<I18N::LangTags> has functions for dealing with RFC3066-style
520 language tags, by Sean Burke. See L<I18N::LangTags>.
524 C<ExtUtils::Constant> is a new tool for extension writers for
525 generating XS code to import C header constants, by Nicholas Clark.
526 See L<ExtUtils::Constant>.
530 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
531 from Damian Conway. See L<Filter::Simple>.
537 use Filter::Simple sub {
538 while (my ($from, $to) = splice @_, 0, 2) {
547 use MyFilter qr/red/ => 'green';
549 print "red\n"; # this code is filtered, will print "green\n"
550 print "bored\n"; # this code is filtered, will print "bogreen\n"
554 print "red\n"; # this code is not filtered, will print "red\n"
558 C<File::Temp> allows one to create temporary files and directories in
559 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
563 C<Filter::Util::Call> provides you with the framework to write
564 I<Source Filters> in Perl, from Paul Marquess. For most uses the
565 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
569 L<libnet> is a collection of perl5 modules related to network
570 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
571 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
573 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
577 C<List::Util> is a selection of general-utility list subroutines, like
578 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
582 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
583 C<Locale::Language>, from Neil Bowers, have been added. They provide the
584 codes for various locale standards, such as "fr" for France, "usd" for
585 US Dollar, and "jp" for Japanese.
589 $country = code2country('jp'); # $country gets 'Japan'
590 $code = country2code('Norway'); # $code gets 'no'
592 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
593 and L<Locale::Language>.
597 C<Locale::Maketext> is localization framework from Sean Burke. See
598 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
599 article about software localization, originally published in The Perl
600 Journal #13, republished here with kind permission.
604 C<Memoize> can make your functions faster by trading space for time,
605 from Mark-Jason Dominus. See L<Memoize>.
609 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
610 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
615 $encoded = encode_base64('Aladdin:open sesame');
616 $decoded = decode_base64($encoded);
618 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
624 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
625 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
626 Extensions)>, from Gisle Aas.
628 use MIME::QuotedPrint;
630 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
631 $decoded = decode_qp($encoded);
633 print $encoded, "\n"; # "Smiley in Unicode: =263A"
635 MIME::QuotedPrint has been enhanced to provide the basic methods
636 necessary to use it with PerlIO::Via as in :
638 use MIME::QuotedPrint;
639 open($fh,">Via(MIME::QuotedPrint)",$path);
641 See L<MIME::QuotedPrint>.
645 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
650 C<open> is a new pragma for setting the default I/O disciplines
655 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
656 Perl scalars as discussed above, from Nick Ing-Simmons. It also
657 serves as an example of a loadable PerlIO layer. Other future
658 possibilities include PerlIO::Array and PerlIO::Code.
659 See L<PerlIO::Scalar>.
663 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
664 functionality provided by a class (typically implemented in perl
665 code), from Nick Ing-Simmons.
667 use MIME::QuotedPrint;
668 open($fh,">Via(MIME::QuotedPrint)",$path);
670 This will automatically convert everything output to C<$fh>
671 to Quoted-Printable. See L<PerlIO::Via>.
675 C<Pod::ParseLink>, by Russ Allbery, has been added,
676 to parse LZ<><> links in pods as described in the new
681 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
682 It converts POD data to formatted overstrike text.
683 See L<Pod::Text::Overstrike>.
687 C<Scalar::Util> is a selection of general-utility scalar subroutines,
688 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
692 C<sort> is a new pragma for controlling the behaviour of sort().
696 C<Storable> gives persistence to Perl data structures by allowing the
697 storage and retrieval of Perl data to and from files in a fast and
698 compact binary format, from Raphael Manfredi. See L<Storable>.
702 C<Switch>, from Damian Conway, has been added. Just by saying
706 you have C<switch> and C<case> available in Perl.
712 case 1 { print "number 1" }
713 case "a" { print "string a" }
714 case [1..10,42] { print "number in list" }
715 case (@array) { print "number in list" }
716 case /\w+/ { print "pattern" }
717 case qr/\w+/ { print "pattern" }
718 case (%hash) { print "entry in hash" }
719 case (\%hash) { print "entry in hash" }
720 case (\&sub) { print "arg to subroutine" }
721 else { print "previous case not true" }
728 C<Test::More> is yet another framework for writing test scripts,
729 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
733 C<Test::Simple> has basic utilities for writing tests, by Michael
734 Schwern. See L<Test::Simple>.
738 C<Text::Balanced> has been added, for extracting delimited text
739 sequences from strings, from Damian Conway.
741 use Text::Balanced 'extract_delimited';
743 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
745 $a will be "'never say never'", $b will be ', he never said'.
747 In addition to extract_delimited() there are also extract_bracketed(),
748 extract_quotelike(), extract_codeblock(), extract_variable(),
749 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
750 gen_extract_tagged(). With these you can implement rather advanced
751 parsing algorithms. See L<Text::Balanced>.
755 C<threads> is an interface to interpreter threads, by Arthur Bergman.
756 Interpreter threads (ithreads) is the new thread model introduced in
757 Perl 5.6 but only available as an internal interface for extension
758 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
762 C<threads::shared> allows data sharing for interpreter threads, from
763 Arthur Bergman. In the ithreads model any data sharing between
764 threads must be explicit, as opposed to the old 5.005 thread model
765 where data sharing was implicit. See L<threads::shared>.
769 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
770 references (unlike the standard Tie::RefHash) The module is contained
771 within Tie::RefHash, see L<Tie::RefHash>.
775 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
776 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
780 C<Unicode::UCD> offers a querying interface to the Unicode Character
781 Database. See L<Unicode::UCD>.
785 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
786 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
790 C<Unicode::Normalize> implements the various Unicode normalization
791 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
795 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
796 typemaps. Nothing gets installed but for extension writers the code
801 =head2 Updated And Improved Modules and Pragmata
807 The following independently supported modules have been updated to the
808 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
809 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
810 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
811 Term::ANSIColor, Test, Text-Tabs+Wrap.
815 The attributes::reftype() now works on tied arguments.
819 AutoLoader can now be disabled with C<no AutoLoader;>.
823 B::Deparse has been significantly enhanced. It now can deparse almost
824 all of the standard test suite (so that the tests still succeed).
825 There is a make target "test.deparse" for trying this out.
829 Class::Struct can now define the classes in compile time.
833 Class::Struct now assigns the array/hash element if the accessor
834 is called with an array/hash element as the B<sole> argument.
838 Data::Dumper has now an option to sort hashes.
842 Data::Dumper has now an option to dump code references
847 DB_File now supports newer Berkeley DB versions, among
852 The English module can now be used without the infamous performance
855 use English '-no_performance_hit';
857 (Assuming, of course, that one doesn't need the troublesome variables
858 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
859 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
863 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
864 new-style constant dispatch section (see L<ExtUtils::Constant>).
865 This means that they will be more robust and hopefully faster.
869 File::Find now chdir()s correctly when chasing symbolic links.
873 File::Find now has pre- and post-processing callbacks. It also
874 correctly changes directories when chasing symbolic links. Callbacks
875 (naughtily) exiting with "next;" instead of "return;" now work.
879 File::Find is now (again) reentrant. It also has been made
884 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
885 prototype mismatch with CORE::glob().
889 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
890 the returned list of filenames.
894 Devel::Peek now has an interface for the Perl memory statistics
895 (this works only if you are using perl's malloc, and if you have
896 compiled with debugging).
900 IPC::Open3 now allows the use of numeric file descriptors.
904 IO::Socket has now atmark() method, which returns true if the socket
905 is positioned at the out-of-band mark. The method is also exportable
906 as a sockatmark() function.
910 IO::Socket::INET has support for ReusePort option (if your platform
911 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
912 you may want to prefer ReuseAddr.
916 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
917 that the operating system will make one up.)
921 use lib now works identically to @INC. Removing directories
922 with 'no lib' now works.
926 Math::BigFloat and Math::BigInt have undergone a full rewrite.
927 They are now magnitudes faster, and they support various
928 bignum libraries such as GMP and PARI as their backends.
932 Math::Complex handles inf, NaN etc., better.
936 Net::Ping has been enhanced. There is now "external" protocol which
937 uses Net::Ping::External module which runs external ping(1) and parses
938 the output. A version of Net::Ping::External is available in CPAN.
942 POSIX::sigaction() is now much more flexible and robust.
943 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
944 handlers, installing new handlers was not atomic.
948 In Safe the C<%INC> now localised in a Safe compartment so that
953 In SDBM_File on dosish platforms, some keys went missing because of
954 lack of support for files with "holes". A workaround for the problem
959 In Search::Dict one can now have a pre-processing hook for the
960 lines being searched.
964 The Shell module now has an OO interface.
968 The Test module has been significantly enhanced.
972 The vars pragma now supports declaring fully qualified variables.
973 (Something that C<our()> does not and will not support.)
977 The utf8:: name space (as in the pragma) provides various
978 Perl-callable functions to provide low level access to Perl's
979 internal Unicode representation. At the moment only length()
980 has been implemented.
984 =head1 Utility Changes
990 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
995 F<emacs/e2ctags.pl> is now much faster.
999 C<h2ph> now supports C trigraphs.
1003 C<h2xs> now produces a template README.
1007 C<h2xs> now uses C<Devel::PPort> for better portability between
1008 different versions of Perl.
1012 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
1013 newly created extensions that define constants. Since the new code is
1014 more correct (if you have two constants where the first one is a
1015 prefix of the second one, the first constant B<never> gets defined),
1016 less lossy (it uses integers for integer constant, as opposed to the
1017 old code that used floating point numbers even for integer constants),
1018 and slightly faster, you might want to consider regenerating your
1019 extension code (the new scheme makes regenerating easy).
1020 L<h2xs> now also supports C trigraphs.
1024 C<libnetcfg> has been added to configure the libnet.
1028 C<perlbug> is now much more robust. It also sends the bug report to
1029 perl.org, not perl.com.
1033 C<perlcc> has been rewritten and its user interface (that is,
1034 command line) is much more like that of the UNIX C compiler, cc.
1035 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1039 C<perlivp> is a new Installation Verification Procedure utility
1040 for running any time after installing Perl.
1044 C<pod2html> now allows specifying a cache directory.
1048 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1049 implementation of sed in Perl: you can use the sed functionality by
1050 using the C<psed> utility.)
1054 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1058 C<xsubpp> now supports OUT keyword.
1062 =head1 New Documentation
1068 perl56delta details the changes between the 5.005 release and the
1073 perlclib documents the internal replacements for standard C library
1074 functions. (Interesting only for extension writers and Perl core
1079 perldebtut is a Perl debugging tutorial.
1083 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1087 perlintro is a gentle introduction to Perl.
1091 perliol documents the internals of PerlIO with layers.
1095 perlmodstyle is a style guide for writing modules.
1099 perlnewmod tells about writing and submitting a new module.
1103 perlpacktut is a pack() tutorial.
1107 perlpod has been rewritten to be clearer and to record the best
1108 practices gathered over the years.
1112 perlpodspec is a more formal specification of the pod format,
1113 mainly of interest for writers of pod applications, not to
1114 people writing in pod.
1118 perlretut is a regular expression tutorial.
1122 perlrequick is a regular expressions quick-start guide.
1123 Yes, much quicker than perlretut.
1127 perltodo has been updated.
1131 perltootc has been renamed as perltooc (to not to conflict
1132 with perltoot in filesystems restricted to "8.3" names)
1136 perluniintro is an introduction to using Unicode in Perl
1137 (perlunicode is more of a reference)
1141 perlutil explains the command line utilities packaged with the Perl
1146 The following platform-specific documents are available before
1147 the installation as README.I<platform>, and after the installation
1150 perlaix perlamiga perlapollo perlbeos perlbs2000
1151 perlce perlcygwin perldgux perldos perlepoc perlhpux
1152 perlhurd perlmachten perlmacos perlmint perlmpeix
1153 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1154 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1160 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1161 confusion with the Perl POSIX module.
1165 The documentation for the WinCE platform is called "CE", to avoid
1166 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1170 =head1 Performance Enhancements
1176 map() could get pathologically slow when the result list it generates
1177 is larger than the source list. The performance has been improved for
1182 sort() has been changed to use primarily mergesort internally as
1183 opposed to the earlier quicksort. For very small lists this may
1184 result in slightly slower sorting times, but in general the speedup
1185 should be at least 20%. Additional bonuses are that the worst case
1186 behaviour of sort() is now better (in computer science terms it now
1187 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1188 worst-case run time behaviour), and that sort() is now stable
1189 (meaning that elements with identical keys will stay ordered as they
1190 were before the sort). See the C<sort> pragma for information.
1192 The story in more detail: suppose you want to serve yourself a little
1195 @digits = ( 3,1,4,1,5,9 );
1197 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1198 Which C<1> comes first is hard to know, since one C<1> looks pretty
1199 much like any other. You can regard this as totally trivial,
1200 or somewhat profound. However, if you just want to sort the even
1201 digits ahead of the odd ones, then what will
1203 sort { ($a % 2) <=> ($b % 2) } @digits;
1205 yield? The only even digit, C<4>, will come first. But how about
1206 the odd numbers, which all compare equal? With the quicksort algorithm
1207 used to implement Perl 5.6 and earlier, the order of ties is left up
1208 to the sort. So, as you add more and more digits of Pi, the order
1209 in which the sorted even and odd digits appear will change.
1210 and, for sufficiently large slices of Pi, the quicksort algorithm
1211 in Perl 5.8 won't return the same results even if reinvoked with the
1212 same input. The justification for this rests with quicksort's
1213 worst case behavior. If you run
1215 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1217 (something you might approximate if you wanted to merge two sorted
1218 arrays using sort), doubling $N doesn't just double the quicksort time,
1219 it I<quadruples> it. Quicksort has a worst case run time that can
1220 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1221 on patterns that may well arise in normal use. You won't notice this
1222 for small arrays, but you I<will> notice it with larger arrays,
1223 and you may not live long enough for the sort to complete on arrays
1224 of a million elements. So the 5.8 quicksort scrambles large arrays
1225 before sorting them, as a statistical defence against quadratic behaviour.
1226 But that means if you sort the same large array twice, ties may be
1227 broken in different ways.
1229 Because of the unpredictability of tie-breaking order, and the quadratic
1230 worst-case behaviour, quicksort was I<almost> replaced completely with
1231 a stable mergesort. I<Stable> means that ties are broken to preserve
1232 the original order of appearance in the input array. So
1234 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1236 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1237 appear in the output in the same order they appeared in the input.
1238 Mergesort has worst case O(NlogN) behaviour, the best value
1239 attainable. And, ironically, this mergesort does particularly
1240 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1241 in O(N) time. But quicksort was rescued at the last moment because
1242 it is faster than mergesort on certain inputs and platforms.
1243 For example, if you really I<don't> care about the order of even
1244 and odd digits, quicksort will run in O(N) time; it's very good
1245 at sorting many repetitions of a small number of distinct elements.
1246 The quicksort divide and conquer strategy works well on platforms
1247 with relatively small, very fast, caches. Eventually, the problem gets
1248 whittled down to one that fits in the cache, from which point it
1249 benefits from the increased memory speed.
1251 Quicksort was rescued by implementing a sort pragma to control aspects
1252 of the sort. The B<stable> subpragma forces stable behaviour,
1253 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1254 subpragmas are heavy-handed ways to select the underlying implementation.
1255 The leading C<_> is a reminder that these subpragmas may not survive
1256 beyond 5.8. More appropriate mechanisms for selecting the implementation
1257 exist, but they wouldn't have arrived in time to save quicksort.
1261 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1262 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1263 reasonably fast while producing a much better spread of values than
1264 the old hashing algorithm (originally by Chris Torek, later tweaked by
1265 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1266 all 3-char printable ASCII keys comes much closer to passing the
1267 DIEHARD random number generation tests. According to perlbench, this
1268 change has not affected the overall speed of Perl.
1272 unshift() should now be noticeably faster.
1276 =head1 Installation and Configuration Improvements
1278 =head2 Generic Improvements
1284 INSTALL now explains how you can configure Perl to use 64-bit
1285 integers even on non-64-bit platforms.
1289 Policy.sh policy change: if you are reusing a Policy.sh file
1290 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1291 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1292 them will now be changed to the new prefix, /foo/bar. (Previously
1293 only $prefix changed.) If you do not like this new behaviour,
1294 specify prefix, siteprefix, and vendorprefix explicitly.
1298 A new optional location for Perl libraries, otherlibdirs, is available.
1299 It can be used for example for vendor add-ons without disturbing Perl's
1300 own library directories.
1304 In many platforms the vendor-supplied 'cc' is too stripped-down to
1305 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1306 to be the case and 'cc' does not seem to be the GNU C compiler
1307 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1311 gcc needs to closely track the operating system release to avoid
1312 build problems. If Configure finds that gcc was built for a different
1313 operating system release than is running, it now gives a clearly visible
1314 warning that there may be trouble ahead.
1318 If binary compatibility with the 5.005 release is not wanted, Configure
1319 no longer suggests including the 5.005 modules in @INC.
1323 Configure C<-S> can now run non-interactively.
1327 Configure support for pdp11-style memory models has been removed due
1332 configure.gnu now works with options with whitespace in them.
1336 installperl now outputs everything to STDERR.
1340 $Config{byteorder} is now computed dynamically (this is more robust
1341 with "fat binaries" where an executable image contains binaries for
1342 more than one binary platform.)
1346 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1347 get appended to the $Config{archname} (also known as $^O) anymore.
1348 Instead, if you explicitly choose not to use perlio (Configure command
1349 line option -Uuseperlio), you will get "-stdio" appended.
1353 Another change related to the architecture name is that "-64all"
1354 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1355 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1359 In AFS installations one can configure the root of the AFS to be
1360 somewhere else than the default F</afs> by using the Configure
1361 parameter C<-Dafsroot=/some/where/else>.
1365 APPLLIB_EXP, a less-know configuration-time definition, has been
1366 documented. It can be used to prepend site-specific directories
1367 to Perl's default search path (@INC), see INSTALL for information.
1371 The version of Berkeley DB used when the Perl (and, presumably, the
1372 DB_File extension) was built is now available as
1373 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1374 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1375 DB_VERSION_PATCH_CFG> from C.
1379 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1380 has been documented in INSTALL.
1384 If you have CPAN access (either network or a local copy such as a
1385 CD-ROM) you can during specify extra modules to Configure to build and
1386 install with Perl using the -Dextras=... option. See INSTALL for
1391 In addition to config.over a new override file, config.arch, is
1392 available. That is supposed to be used by hints file writers for
1393 architecture-wide changes (as opposed to config.over which is for
1398 If your file system supports symbolic links you can build Perl outside
1399 of the source directory by
1401 mkdir /tmp/perl/build/directory
1402 cd /tmp/perl/build/directory
1403 sh /path/to/perl/source/Configure -Dmksymlinks ...
1405 This will create in /tmp/perl/build/directory a tree of symbolic links
1406 pointing to files in /path/to/perl/source. The original files are left
1407 unaffected. After Configure has finished you can just say
1411 and Perl will be built and tested, all in /tmp/perl/build/directory.
1415 For Perl developers several new make targets for profiling
1416 and debugging have been added, see L<perlhack>.
1422 Use of the F<gprof> tool to profile Perl has been documented in
1423 L<perlhack>. There is a make target called "perl.gprof" for
1424 generating a gprofiled Perl executable.
1428 If you have GCC 3, there is a make target called "perl.gcov" for
1429 creating a gcoved Perl executable for coverage analysis. See
1434 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1435 have been added, see L<perlhack> for more information about pixie and
1442 Guidelines of how to construct minimal Perl installations have
1443 been added to INSTALL.
1447 The Thread extension is now not built at all under ithreads
1448 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1449 Thread extension requires being Configured with C<-Duse5005threads>).
1451 But note that the Thread.pm interface is now shared by both
1456 =head2 New Or Improved Platforms
1458 For the list of platforms known to support Perl,
1459 see L<perlport/"Supported Platforms">.
1465 AIX dynamic loading should be now better supported.
1469 AIX should now work better with gcc, threads, and 64-bitness. Also the
1470 long doubles support in AIX should be better now. See L<perlaix>.
1474 After a long pause, AmigaOS has been verified to be happy with Perl.
1478 AtheOS (http://www.atheos.cx/) is a new platform.
1482 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1486 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1490 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1491 have been regained. Many test suite tests still fail and the
1492 co-existence of Unicode and EBCDIC isn't quite settled, but the
1493 situation is much better than with Perl 5.6. See L<perlos390>,
1494 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1498 Building perl with -Duseithreads or -Duse5005threads now works under
1499 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1500 need a thread library package installed. See README.hpux.
1504 MacOS Classic (MacPerl has of course been available since
1505 perl 5.004 but now the source code bases of standard Perl
1506 and MacPerl have been synchronised)
1510 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1511 filesystems. (The case-insensitivity confused the Perl build process.)
1515 NCR MP-RAS is now supported.
1519 NetWare from Novell is now supported. See L<perlnetware>.
1523 NonStop-UX is now supported.
1527 NEC SUPER-UX is now supported.
1531 Amdahl UTS UNIX mainframe platform is now supported.
1535 WinCE is now supported. See L<perlce>.
1539 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1540 support for dynamic loading. This is not selected by default,
1541 however, you must specify -Dusedl in the arguments of Configure.
1545 =head1 Selected Bug Fixes
1547 Numerous memory leaks and uninitialized memory accesses have been
1548 hunted down. Most importantly anonymous subs used to leak quite
1555 The autouse pragma didn't work for Multi::Part::Function::Names.
1559 caller() could cause core dumps in certain situations. Carp was sometimes
1560 affected by this problem.
1564 chop(@list) in list context returned the characters chopped in
1565 reverse order. This has been reversed to be in the right order.
1569 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1570 when building the Perl binary. The only exception to this is SunOS 4.x,
1575 The behaviour of non-decimal but numeric string constants such as
1576 "0x23" was platform-dependent: in some platforms that was seen as 35,
1577 in some as 0, in some as a floating point number (don't ask). This
1578 was caused by Perl using the operating system libraries in a situation
1579 where the result of the string to number conversion is undefined: now
1580 Perl consistently handles such strings as zero in numeric contexts.
1584 The order of DESTROYs has been made more predictable.
1588 Several debugger fixes: exit code now reflects the script exit code,
1589 condition C<"0"> now treated correctly, the C<d> command now checks
1590 line number, the C<$.> no longer gets corrupted, all debugger output
1591 now goes correctly to the socket if RemotePort is set.
1595 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1596 when statically building extensions into perl. This has been corrected.
1600 L<dprofpp> -R didn't work.
1604 C<*foo{FORMAT}> now works.
1607 Infinity is now recognized as a number.
1611 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1612 the Tk extension with 5.6.0.)
1616 Lexicals I: lexicals outside an eval "" weren't resolved
1617 correctly inside a subroutine definition inside the eval "" if they
1618 were not already referenced in the top level of the eval""ed code.
1622 Lexicals II: lexicals leaked at file scope into subroutines that
1623 were declared before the lexicals.
1627 Lexical warnings now propagating correctly between scopes
1628 and into C<eval "...">.
1632 C<use warnings qw(FATAL all)> did not work as intended. This has been
1637 warnings::enabled() now reports the state of $^W correctly if the caller
1638 isn't using lexical warnings.
1642 Line renumbering with eval and C<#line> now works.
1646 Fixed numerous memory leaks, especially in eval "".
1650 mkdir() now ignores trailing slashes in the directory name,
1651 as mandated by POSIX.
1655 Some versions of glibc have a broken modfl(). This affects builds
1656 with C<-Duselongdouble>. This version of Perl detects this brokenness
1657 and has a workaround for it. The glibc release 2.2.2 is known to have
1658 fixed the modfl() bug.
1662 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1663 return 27406, instead of 27047).
1667 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1668 more compatible with 5.005. Infinity is now recognised as a number.
1672 Numeric conversions did not recognize changes in the string value
1673 properly in certain circumstances.
1677 Attributes (like :shared) didn't work with our().
1681 our() variables will not cause "will not stay shared" warnings.
1685 "our" variables of the same name declared in two sibling blocks
1686 resulted in bogus warnings about "redeclaration" of the variables.
1687 The problem has been corrected.
1691 pack "Z" now correctly terminates the string with "\0".
1695 Fix password routines which in some shadow password platforms
1696 (e.g. HP-UX) caused getpwent() to return every other entry.
1700 The PERL5OPT environment variable (for passing command line arguments
1701 to Perl) didn't work for more than a single group of options.
1705 PERL5OPT with embedded spaces didn't work.
1709 printf() no longer resets the numeric locale to "C".
1713 C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1717 pos() did not return the correct value within s///ge in earlier
1718 versions. This is now handled correctly.
1722 Printing quads (64-bit integers) with printf/sprintf now works
1723 without the q L ll prefixes (assuming you are on a quad-capable platform).
1727 Regular expressions on references and overloaded scalars now work.
1731 Right-hand side magic (GMAGIC) could in many cases such as string
1732 concatenation be invoked too many times.
1736 scalar() now forces scalar context even when used in void context.
1740 SOCKS support is now much more robust.
1744 sort() arguments are now compiled in the right wantarray context
1745 (they were accidentally using the context of the sort() itself).
1746 The comparison block is now run in scalar context, and the arguments
1747 to be sorted are always provided list context.
1751 Changed the POSIX character class C<[[:space:]]> to include the (very
1752 rarely used) vertical tab character. Added a new POSIX-ish character
1753 class C<[[:blank:]]> which stands for horizontal whitespace
1754 (currently, the space and the tab).
1758 The tainting behaviour of sprintf() has been rationalized. It does
1759 not taint the result of floating point formats anymore, making the
1760 behaviour consistent with that of string interpolation.
1764 Some cases of inconsistent taint propagation (such as within hash
1765 values) have been fixed.
1769 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1770 of simple pattern matches. These are now handled better.
1774 Regular expression debug output (whether through C<use re 'debug'>
1775 or via C<-Dr>) now looks better.
1779 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
1784 Use of $& could trigger a core dump under some situations. This
1789 The regular expression captured submatches ($1, $2, ...) are now
1790 more consistently unset if the match fails, instead of leaving false
1791 data lying around in them.
1795 readline() on files opened in "slurp" mode could return an extra "" at
1796 the end in certain situations. This has been corrected.
1800 Autovivification of symbolic references of special variables described
1801 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
1806 Sys::Syslog ignored the C<LOG_AUTH> constant.
1810 All but the first argument of the IO syswrite() method are now optional.
1814 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1815 in multiple threads simultaneously are now thread-safe.
1819 Tie::ARRAY SPLICE method was broken.
1823 Allow read-only string on left hand side of non-modifying tr///.
1827 Several Unicode fixes.
1833 BOMs (byte order marks) in the beginning of Perl files
1834 (scripts, modules) should now be transparently skipped.
1835 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1839 The character tables have been updated to Unicode 3.1.1.
1843 Comparing with utf8 data does not magically upgrade non-utf8 data
1848 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1852 Concatenation with the C<.> operator or via variable interpolation,
1853 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1854 substitution with C<s///>, single-quoted UTF8, should now work.
1858 The C<tr///> operator now works. Note that the C<tr///CU>
1859 functionality has been removed (but see pack('U0', ...)).
1863 C<eval "v200"> now works.
1867 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
1868 This has been corrected.
1872 Zero entries were missing from the Unicode classes like C<IsDigit>.
1878 Large unsigned numbers (those above 2**31) could sometimes lose their
1879 unsignedness, causing bogus results in arithmetic operations.
1883 =head2 Platform Specific Changes and Fixes
1891 Perl now works on post-4.0 BSD/OSes.
1897 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
1903 Numerous updates; currently synchronised with Cygwin 1.1.4.
1907 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1913 EPOC update after Perl 5.6.0. See README.epoc.
1919 Perl now works on post-3.0 FreeBSDs.
1925 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1931 Numerous compilation flag and hint enhancements; accidental mixing
1932 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1942 Long doubles should now work (see INSTALL).
1946 Linux previously had problems related to sockaddrlen when using
1947 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1955 Compilation of the standard Perl distribution in MacOS Classic should
1956 now work if you have the Metrowerks development environment and
1957 the missing Mac-specific toolkit bits. Contact the macperl mailing
1964 MPE/iX update after Perl 5.6.0. See README.mpeix.
1970 Perl now works on NetBSD/sparc.
1976 Now works with usethreads (see INSTALL).
1982 64-bitness using the Sun Workshop compiler now works.
1986 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1988 The operating system version letter now recorded in $Config{osvers}.
1989 Allow compiling with gcc (previously explicitly forbidden). Compiling
1990 with gcc still not recommended because buggy code results, even with
1997 Fixed various alignment problems that lead into core dumps either
1998 during build or later; no longer dies on math errors at runtime;
1999 now using full quad integers (64 bits), previously was using
2000 only 46 bit integers for speed.
2006 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2007 (see INSTALL); now works with Perl's malloc.
2009 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2010 unimplemented. It now works as documented.
2012 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2013 was that a pid of -1 would cause a wildcard search of all processes on
2014 the system. The most significant enhancement is that we can now
2015 usually get the completion status of a terminated process.
2017 POSIX-style signals are now emulated much better on VMS versions prior
2020 The C<system> function and backticks operator have improved
2021 functionality and better error handling.
2031 accept() no longer leaks memory.
2035 Borland C++ v5.5 is now a supported compiler that can build Perl.
2036 However, the generated binaries continue to be incompatible with those
2037 generated by the other supported compilers (GCC and Visual C++).
2041 Better chdir() return value for a non-existent directory.
2045 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2049 New %ENV entries now propagate to subprocesses.
2053 Current directory entries in %ENV are now correctly propagated to child
2058 $ENV{LIB} now used to search for libs under Visual C.
2062 fork() emulation has been improved in various ways, but still continues
2063 to be experimental. See L<perlfork> for known bugs and caveats.
2067 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2071 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2072 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2076 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2080 The makefiles now provide a single switch to bulk-enable all the features
2081 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2085 Allow REG_EXPAND_SZ keys in the registry.
2089 Can now send() from all threads, not just the first one.
2093 Fake signal handling reenabled, bugs and all.
2097 %SIG has been enabled under USE_ITHREADS, but its use is completely
2098 unsupported under all configurations.
2102 Less stack reserved per thread so that more threads can run
2103 concurrently. (Still 16M per thread.)
2107 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
2108 (works better when perl is running as service).
2112 Better UNC path handling under ithreads.
2116 wait(), waitpid() and backticks now return the correct exit status under
2121 winsock handle leak fixed.
2127 =head1 New or Changed Diagnostics
2133 All regular expression compilation error messages are now hopefully
2134 easier to understand both because the error message now comes before
2135 the failed regex and because the point of failure is now clearly
2136 marked by a C<E<lt>-- HERE> marker.
2140 The various "opened only for", "on closed", "never opened" warnings
2141 drop the C<main::> prefix for filehandles in the C<main> package,
2142 for example C<STDIN> instead of C<main::STDIN>.
2146 The "Unrecognized escape" warning has been extended to include C<\8>,
2147 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2151 Two new debugging options have been added: if you have compiled your
2152 Perl with debugging, you can use the -DT and -DR options to trace
2153 tokenising and to add reference counts to displaying variables,
2158 If an attempt to use a (non-blessed) reference as an array index
2159 is made, a warning is given.
2163 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2164 now give a warning. This may be a problem for generated and evaled
2169 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2170 using the C<"C"> format you will get an optional warning. Similarly
2171 for the C<"c"> format and a number less than -128 or more than 127.
2175 Certain regex modifiers such as C<(?o)> make sense only if applied to
2176 the entire regex. You will an optional warning if you try to do otherwise.
2180 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2181 has been deprecated for a while. Now you will get an optional warning.
2185 =head1 Changed Internals
2191 perlapi.pod (a companion to perlguts) now attempts to document the
2196 You can now build a really minimal perl called microperl.
2197 Building microperl does not require even running Configure;
2198 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2199 many assumptions, some of which may be too bold; the resulting
2200 executable may crash or otherwise misbehave in wondrous ways.
2201 For careful hackers only.
2205 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2206 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2207 interfaces to the publicised API. For the full list of the available
2208 APIs see L<perlapi>.
2212 Made possible to propagate customised exceptions via croak()ing.
2216 Now xsubs can have attributes just like subs. (Well, at least the
2217 built-in attributes.)
2221 dTHR and djSP have been obsoleted; the former removed (because it's
2222 a no-op) and the latter replaced with dSP.
2226 PERL_OBJECT has been completely removed.
2230 The MAGIC constants (e.g. C<'P'>) have been macrofied
2231 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2232 and maintainability.
2236 The regex compiler now maintains a structure that identifies nodes in
2237 the compiled bytecode with the corresponding syntactic features of the
2238 original regex expression. The information is attached to the new
2239 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2240 complete information.
2244 The C code has been made much more C<gcc -Wall> clean. Some warning
2245 messages still remain in some platforms, so if you are compiling with
2246 gcc you may see some warnings about dubious practices. The warnings
2247 are being worked on.
2251 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2255 Documentation on how to use the Perl source repository has been added
2256 to F<Porting/repository.pod>.
2260 There are now several profiling make targets.
2264 =head1 Security Vulnerability Closed
2266 (This change was already made in 5.7.0 but bears repeating here.)
2268 A potential security vulnerability in the optional suidperl component
2269 of Perl was identified in August 2000. suidperl is neither built nor
2270 installed by default. As of November 2001 the only known vulnerable
2271 platform is Linux, most likely all Linux distributions. CERT and
2272 various vendors and distributors have been alerted about the vulnerability.
2273 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2274 for more information.
2276 The problem was caused by Perl trying to report a suspected security
2277 exploit attempt using an external program, /bin/mail. On Linux
2278 platforms the /bin/mail program had an undocumented feature which
2279 when combined with suidperl gave access to a root shell, resulting in
2280 a serious compromise instead of reporting the exploit attempt. If you
2281 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2282 suidperl is not installed, you are safe.
2284 The exploit attempt reporting feature has been completely removed from
2285 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2286 from all the Perl 5.7 releases), so that particular vulnerability
2287 isn't there anymore. However, further security vulnerabilities are,
2288 unfortunately, always possible. The suidperl functionality is most
2289 probably going to be removed in Perl 5.10. In any case, suidperl
2290 should only be used by security experts who know exactly what they are
2291 doing and why they are using suidperl instead of some other solution
2292 such as sudo (see http://www.courtesan.com/sudo/).
2296 Several new tests have been added, especially for the F<lib>
2297 subsection. There are now about 34 000 individual tests (spread over
2298 about 530 test scripts), in the regression suite (5.6.1 has about
2299 11700 tests, in 258 test scripts) Many of the new tests are introduced
2300 by the new modules, but still in general Perl is now more thoroughly
2303 Because of the large number of tests, running the regression suite
2304 will take considerably longer time than it used to: expect the suite
2305 to take up to 4-5 times longer to run than in perl 5.6. In a really
2306 fast machine you can hope to finish the suite in about 5 minutes
2309 The tests are now reported in a different order than in earlier Perls.
2310 (This happens because the test scripts from under t/lib have been moved
2311 to be closer to the library/extension they are testing.)
2313 =head1 Known Problems
2321 In AIX 4.2 Perl extensions that use C++ functions that use statics
2322 may have problems in that the statics are not getting initialized.
2323 In newer AIX releases this has been solved by linking Perl with
2324 the libC_r library, but unfortunately in AIX 4.2 the said library
2325 has an obscure bug where the various functions related to time
2326 (such as time() and gettimeofday()) return broken values, and
2327 therefore in AIX 4.2 Perl is not linked against the libC_r.
2331 vac 5.0.0.0 May Produce Buggy Code For Perl
2333 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2334 resulting in few random tests failing, but when the failing tests
2335 are run by hand, they succeed. We suggest upgrading to at least
2336 vac version 5.0.1.0, that has been known to compile Perl correctly.
2337 "lslpp -L|grep vac.C" will tell you the vac version.
2341 =head2 Amiga Perl Invoking Mystery
2343 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2344 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2345 known but the current suspect is the F<ixemul> library.
2347 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2349 Don't panic. Read INSTALL 'make test' section instead.
2351 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2353 The subtests 11 and 12 sometimes fail and sometimes work.
2355 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2357 The lib/io_multihomed test may hang in HP-UX if Perl has been
2358 configured to be 64-bit. Because other 64-bit platforms do not hang in
2359 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2360 test attempts to create and connect to "multihomed" sockets (sockets
2361 which have multiple IP addresses).
2363 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2365 If perl is configured with -Duse64bitall, the successful result of the
2366 subtest 10 of lib/posix may arrive before the successful result of the
2367 subtest 9, which confuses the test harness so much that it thinks the
2370 =head2 Linux With Sfio Fails op/misc Test 48
2376 The following tests are known to fail:
2378 Failed Test Stat Wstat Total Fail Failed List of Failed
2379 -------------------------------------------------------------------------
2380 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2381 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2382 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2383 ../lib/warnings.t 450 1 0.22% 316
2387 OS/390 has rather many test failures but the situation is actually
2388 better than it was in 5.6.0, it's just that so many new modules and
2389 tests have been added.
2391 Failed Test Stat Wstat Total Fail Failed List of Failed
2392 -----------------------------------------------------------------------------
2393 ../ext/B/Deparse.t 14 1 7.14% 14
2394 ../ext/B/Showlex.t 1 1 100.00% 1
2395 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2397 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2398 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2399 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2400 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2401 ../lib/warnings.t 434 1 0.23% 75
2402 ../lib/ExtUtils.t 27 1 3.70% 25
2403 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2404 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2405 ../lib/User/pwent.t 9 1 11.11% 4
2406 op/pat.t 660 6 0.91% 242-243 424-425
2408 op/split.t 0 9 ?? ?? % ??
2409 op/taint.t 174 3 1.72% 156 162 168
2410 op/tr.t 70 3 4.29% 50 58-59
2411 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2413 =head2 op/sprintf tests 129 and 130
2415 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2416 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2417 The failing platforms do not comply with the ANSI C Standard, line
2418 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2419 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2420 the printf format "%.0f", most often they produce "0" and "-0".)
2422 =head2 Failure of Thread tests
2424 B<Note that support for 5.005-style threading remains experimental
2425 and practically unsupported.>
2427 The following tests are known to fail due to fundamental problems in
2428 the 5.005 threading implementation. These are not new failures--Perl
2429 5.005_0x has the same bugs, but didn't have these tests.
2431 ext/List/Util/t/first 2
2433 ext/Thread/thr5005 19-20
2435 These failures are unlikely to get fixed.
2443 ext/POSIX/sigaction subtests 6 and 13 may fail.
2447 lib/ExtUtils may spuriously claim that subtest 28 failed,
2448 which is interesting since the test only has 27 tests.
2452 Numerous numerical test failures
2454 op/numconvert 209,210,217,218
2456 ext/Time/HiRes/HiRes 9
2457 lib/Math/BigInt/t/bigintpm 1145
2460 These tests fail because of yet unresolved floating point inaccuracies.
2466 There are a few known test failures, see L<perluts>.
2470 There is one known test failure with a default configuration:
2472 [.run]switches..........................FAILED on test 1
2476 In multi-CPU boxes there are some problems with the I/O buffering:
2477 some output may appear twice.
2479 =head2 Localising a Tied Variable Leaks Memory
2482 tie my %tie_hash => 'Tie::StdHash';
2486 local($tie_hash{Foo}) = 1; # leaks
2488 Code like the above is known to leak memory every time the local()
2491 =head2 Localising Tied Arrays and Hashes Is Broken
2495 doesn't work as one would expect: the old value is restored
2498 =head2 Self-tying of Arrays and Hashes Is Forbidden
2500 Self-tying of arrays and hashes is broken in rather deep and
2501 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2502 frustrated at the mysterious results (core dumps, most often) it is
2503 for now forbidden (you will get a fatal error even from an attempt).
2505 =head2 Building Extensions Can Fail Because Of Largefiles
2507 Some extensions like mod_perl are known to have issues with
2508 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2509 default to 64 bits wide, where supported. Modules may fail to compile
2510 at all or compile and work incorrectly. Currently there is no good
2511 solution for the problem, but Configure now provides appropriate
2512 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2513 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2514 having problems can try configuring themselves without the
2515 largefileness. This is admittedly not a clean solution, and the
2516 solution may not even work at all. One potential failure is whether
2517 one can (or, if one can, whether it's a good idea) link together at
2518 all binaries with different ideas about file offsets, all this is
2521 =head2 Unicode Support on EBCDIC Still Spotty
2523 Though mostly working, Unicode support still has problem spots on
2524 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2525 regular expression constructs for code points less than 256: the
2526 pP are testing for Unicode code points, not knowing about EBCDIC.
2528 =head2 The Compiler Suite Is Still Experimental
2530 The compiler suite is slowly getting better but it continues to be
2531 highly experimental. Use in production environments is discouraged.
2533 =head2 The Long Double Support is Still Experimental
2535 The ability to configure Perl's numbers to use "long doubles",
2536 floating point numbers of hopefully better accuracy, is still
2537 experimental. The implementations of long doubles are not yet
2538 widespread and the existing implementations are not quite mature
2539 or standardised, therefore trying to support them is a rare
2540 and moving target. The gain of more precision may also be offset
2541 by slowdown in computations (more bits to move around, and the
2542 operations are more likely to be executed by less optimised
2545 =head1 Reporting Bugs
2547 If you find what you think is a bug, you might check the articles
2548 recently posted to the comp.lang.perl.misc newsgroup and the perl
2549 bug database at http://bugs.perl.org. There may also be
2550 information at http://www.perl.com/perl/, the Perl Home Page.
2552 If you believe you have an unreported bug, please run the B<perlbug>
2553 program included with your release. Be sure to trim your bug down
2554 to a tiny but sufficient test case. Your bug report, along with the
2555 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2556 analysed by the Perl porting team.
2560 The F<Changes> file for exhaustive details on what changed.
2562 The F<INSTALL> file for how to build Perl.
2564 The F<README> file for general stuff.
2566 The F<Artistic> and F<Copying> files for copyright information.
2570 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.