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 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
230 The prototypes are now checked at compile-time for invalid characters.
231 An optional warning is generated ("Illegal character in prototype...")
232 but this may be upgraded to a fatal error in a future release.
236 =head1 Core Enhancements
238 =head2 PerlIO is Now The Default
244 IO is now by default done via PerlIO rather than system's "stdio".
245 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
246 handle's behaviour. Layers can be specified at open time via 3-arg
249 open($fh,'>:crlf :utf8', $path) || ...
251 or on already opened handles via extended C<binmode>:
253 binmode($fh,':encoding(iso-8859-7)');
255 The built-in layers are: unix (low level read/write), stdio (as in
256 previous Perls), perlio (re-implementation of stdio buffering in a
257 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
258 but available on any platform). A mmap layer may be available if
259 platform supports it (mostly UNIXes).
261 Layers to be applied by default may be specified via the 'open' pragma.
263 See L</"Installation and Configuration Improvements"> for the effects
264 of PerlIO on your architecture name.
268 File handles can be marked as accepting Perl's internal encoding of Unicode
269 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
271 open($fh,">:utf8","Uni.txt");
273 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
274 for you since it's not UTF-8 what you will be getting but instead
275 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
276 http://www.unicode.org/unicode/reports/tr16/ for more information.
277 In future releases this naming may change.
281 File handles can translate character encodings from/to Perl's internal
282 Unicode form on read/write via the ":encoding()" layer.
286 File handles can be opened to "in memory" files held in Perl scalars via:
288 open($fh,'>', \$variable) || ...
292 Anonymous temporary files are available without need to
293 'use FileHandle' or other module via
295 open($fh,"+>", undef) || ...
297 That is a literal undef, not an undefined value.
301 The list form of C<open> is now implemented for pipes (at least on UNIX):
303 open($fh,"-|", 'cat', '/etc/motd')
305 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
312 Perl used to be fragile in that signals arriving at inopportune moments
313 could corrupt Perl's internal state. Now Perl postpones handling of
314 signals until it's safe (between opcodes).
316 This change may have surprising side effects because signals no more
317 interrupt Perl instantly. Perl will now first finish whatever it was
318 doing, like finishing an internal operation (like sort()) or an
319 external operation (like an I/O operation), and only then look at any
320 arrived signals (and before starting the next operation). No more corrupt
321 internal state since the current operation is always finished first,
322 but the signal may take more time to get heard.
324 =head2 Unicode Overhaul
326 Unicode in general should be now much more usable than in Perl 5.6.0
327 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
328 regular expressions should work now, Unicode in tr/// should work now,
329 Unicode in I/O should work now.
335 The Unicode Character Database coming with Perl has been upgraded
336 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
340 For developers interested in enhancing Perl's Unicode capabilities:
341 almost all the UCD files are included with the Perl distribution in
342 the lib/unicore subdirectory. The most notable omission, for space
343 considerations, is the Unihan database.
347 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
348 added. "Blank" is like C isblank(), that is, it contains only
349 "horizontal whitespace" (the space character is, the newline isn't),
350 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
351 isn't, since that includes the vertical tabulator character, whereas
356 =head2 Understanding of Numbers
358 In general a lot of fixing has happened in the area of Perl's
359 understanding of numbers, both integer and floating point. Since in
360 many systems the standard number parsing functions like C<strtoul()>
361 and C<atof()> seem to have bugs, Perl tries to work around their
362 deficiencies. This results hopefully in more accurate numbers.
364 Perl now tries internally to use integer values in numeric conversions
365 and basic arithmetics (+ - * /) if the arguments are integers, and
366 tries also to keep the results stored internally as integers.
367 This change leads to often slightly faster and always less lossy
368 arithmetics. (Previously Perl always preferred floating point numbers
371 =head2 Miscellaneous Enhancements
377 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
378 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
382 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
383 in multiple arguments.)
387 END blocks are now run even if you exit/die in a BEGIN block.
388 Internally, the execution of END blocks is now controlled by
389 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
390 behaviour for Perl embedders. This will default in 5.10. See
395 Formats now support zero-padded decimal fields.
399 Lvalue subroutines can now return C<undef> in list context.
400 However, the lvalue subroutine feature still remains experimental.
404 A new special regular expression variable has been introduced:
405 C<$^N>, which contains the most-recently closed group (submatch).
409 C<no Module;> now works even if there is no "sub unimport" in the Module.
413 The numerical comparison operators return C<undef> if either operand
414 is a NaN. Previously the behaviour was unspecified.
418 The following builtin functions are now overridable: each(), keys(),
419 pop(), push(), shift(), splice(), unshift().
423 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
427 my __PACKAGE__ $obj now works.
431 The printf() and sprintf() now support parameter reordering using the
432 C<%\d+\$> and C<*\d+\$> syntaxes. For example
434 print "%2\$s %1\$s\n", "foo", "bar";
436 will print "bar foo\n". This feature helps in writing
437 internationalised software, and in general when the order
438 of the parameters can vary.
442 prototype(\&) is now available.
446 prototype(\[$@%&]) is now available to implicitly create references
447 (useful for example if you want to emulate the tie() interface).
451 untie() will now call an UNTIE() hook if it exists. See L<perltie>
456 L<utime> now supports C<utime undef, undef, @files> to change the
457 file timestamps to the current time.
461 The rules for allowing underscores (underbars) in numeric constants
462 have been relaxed and simplified: now you can have an underscore
463 simply B<between digits>.
467 =head1 Modules and Pragmata
469 =head2 New Modules and Pragmata
475 C<Attribute::Handlers> allows a class to define attribute handlers.
478 use Attribute::Handlers;
479 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
481 # later, in some package using or inheriting from MyPack...
483 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
485 Both variables and routines can have attribute handlers. Handlers can
486 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
487 exact compilation phase (BEGIN, CHECK, INIT, or END).
491 B<B::Concise> is a new compiler backend for walking the Perl syntax
492 tree, printing concise info about ops, from Stephen McCamant. The
493 output is highly customisable. See L<B::Concise>.
497 C<Class::ISA> for reporting the search path for a class's ISA tree,
498 by Sean Burke, has been added. See L<Class::ISA>.
502 C<Cwd> has now a split personality: if possible, an XS extension is
503 used, (this will hopefully be faster, more secure, and more robust)
504 but if not possible, the familiar Perl implementation is used.
508 C<Devel::PPPort>, originally from Kenneth Albanowski and now
509 maintained by Paul Marquess, has been added. It is primarily used
510 by C<h2xs> to enhance portability of of XS modules between different
515 C<Digest>, frontend module for calculating digests (checksums), from
516 Gisle Aas, has been added. See L<Digest>.
520 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
521 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
523 use Digest::MD5 'md5_hex';
525 $digest = md5_hex("Thirsty Camel");
527 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
529 NOTE: the C<MD5> backward compatibility module is deliberately not
530 included since its further use is discouraged.
534 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
535 between different character encodings. Support for Unicode,
536 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
537 compiled in to the module. Several other encodings (like Japanese,
538 Chinese, and MacIntosh encodings) are included and will be loaded at
539 runtime. See L<Encode>.
541 Any encoding supported by Encode module is also available to the
542 ":encoding()" layer if PerlIO is used.
546 C<I18N::Langinfo> can be use to query locale information.
547 See L<I18N::Langinfo>.
551 C<I18N::LangTags> has functions for dealing with RFC3066-style
552 language tags, by Sean Burke. See L<I18N::LangTags>.
556 C<ExtUtils::Constant> is a new tool for extension writers for
557 generating XS code to import C header constants, by Nicholas Clark.
558 See L<ExtUtils::Constant>.
562 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
563 from Damian Conway. See L<Filter::Simple>.
569 use Filter::Simple sub {
570 while (my ($from, $to) = splice @_, 0, 2) {
579 use MyFilter qr/red/ => 'green';
581 print "red\n"; # this code is filtered, will print "green\n"
582 print "bored\n"; # this code is filtered, will print "bogreen\n"
586 print "red\n"; # this code is not filtered, will print "red\n"
590 C<File::Temp> allows one to create temporary files and directories in
591 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
595 C<Filter::Util::Call> provides you with the framework to write
596 I<Source Filters> in Perl, from Paul Marquess. For most uses the
597 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
601 L<libnet> is a collection of perl5 modules related to network
602 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
603 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
605 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
609 C<List::Util> is a selection of general-utility list subroutines, like
610 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
614 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
615 C<Locale::Language>, from Neil Bowers, have been added. They provide the
616 codes for various locale standards, such as "fr" for France, "usd" for
617 US Dollar, and "jp" for Japanese.
621 $country = code2country('jp'); # $country gets 'Japan'
622 $code = country2code('Norway'); # $code gets 'no'
624 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
625 and L<Locale::Language>.
629 C<Locale::Maketext> is localization framework from Sean Burke. See
630 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
631 article about software localization, originally published in The Perl
632 Journal #13, republished here with kind permission.
636 C<Memoize> can make your functions faster by trading space for time,
637 from Mark-Jason Dominus. See L<Memoize>.
641 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
642 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
647 $encoded = encode_base64('Aladdin:open sesame');
648 $decoded = decode_base64($encoded);
650 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
656 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
657 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
658 Extensions)>, from Gisle Aas.
660 use MIME::QuotedPrint;
662 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
663 $decoded = decode_qp($encoded);
665 print $encoded, "\n"; # "Smiley in Unicode: =263A"
667 MIME::QuotedPrint has been enhanced to provide the basic methods
668 necessary to use it with PerlIO::Via as in :
670 use MIME::QuotedPrint;
671 open($fh,">Via(MIME::QuotedPrint)",$path);
673 See L<MIME::QuotedPrint>.
677 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
682 C<open> is a new pragma for setting the default I/O disciplines
687 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
688 Perl scalars as discussed above, from Nick Ing-Simmons. It also
689 serves as an example of a loadable PerlIO layer. Other future
690 possibilities include PerlIO::Array and PerlIO::Code.
691 See L<PerlIO::Scalar>.
695 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
696 functionality provided by a class (typically implemented in perl
697 code), from Nick Ing-Simmons.
699 use MIME::QuotedPrint;
700 open($fh,">Via(MIME::QuotedPrint)",$path);
702 This will automatically convert everything output to C<$fh>
703 to Quoted-Printable. See L<PerlIO::Via>.
707 C<Pod::ParseLink>, by Russ Allbery, has been added,
708 to parse LZ<><> links in pods as described in the new
713 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
714 It converts POD data to formatted overstrike text.
715 See L<Pod::Text::Overstrike>.
719 C<Scalar::Util> is a selection of general-utility scalar subroutines,
720 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
724 C<sort> is a new pragma for controlling the behaviour of sort().
728 C<Storable> gives persistence to Perl data structures by allowing the
729 storage and retrieval of Perl data to and from files in a fast and
730 compact binary format, from Raphael Manfredi. See L<Storable>.
734 C<Switch>, from Damian Conway, has been added. Just by saying
738 you have C<switch> and C<case> available in Perl.
744 case 1 { print "number 1" }
745 case "a" { print "string a" }
746 case [1..10,42] { print "number in list" }
747 case (@array) { print "number in list" }
748 case /\w+/ { print "pattern" }
749 case qr/\w+/ { print "pattern" }
750 case (%hash) { print "entry in hash" }
751 case (\%hash) { print "entry in hash" }
752 case (\&sub) { print "arg to subroutine" }
753 else { print "previous case not true" }
760 C<Test::More> is yet another framework for writing test scripts,
761 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
765 C<Test::Simple> has basic utilities for writing tests, by Michael
766 Schwern. See L<Test::Simple>.
770 C<Text::Balanced> has been added, for extracting delimited text
771 sequences from strings, from Damian Conway.
773 use Text::Balanced 'extract_delimited';
775 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
777 $a will be "'never say never'", $b will be ', he never said'.
779 In addition to extract_delimited() there are also extract_bracketed(),
780 extract_quotelike(), extract_codeblock(), extract_variable(),
781 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
782 gen_extract_tagged(). With these you can implement rather advanced
783 parsing algorithms. See L<Text::Balanced>.
787 C<threads> is an interface to interpreter threads, by Arthur Bergman.
788 Interpreter threads (ithreads) is the new thread model introduced in
789 Perl 5.6 but only available as an internal interface for extension
790 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
794 C<threads::shared> allows data sharing for interpreter threads, from
795 Arthur Bergman. In the ithreads model any data sharing between
796 threads must be explicit, as opposed to the old 5.005 thread model
797 where data sharing was implicit. See L<threads::shared>.
801 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
802 references (unlike the standard Tie::RefHash) The module is contained
803 within Tie::RefHash, see L<Tie::RefHash>.
807 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
808 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
812 C<Unicode::UCD> offers a querying interface to the Unicode Character
813 Database. See L<Unicode::UCD>.
817 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
818 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
822 C<Unicode::Normalize> implements the various Unicode normalization
823 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
827 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
828 typemaps. Nothing gets installed but for extension writers the code
833 =head2 Updated And Improved Modules and Pragmata
839 The following independently supported modules have been updated to the
840 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
841 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
842 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
843 Term::ANSIColor, Test, Text-Tabs+Wrap.
847 The attributes::reftype() now works on tied arguments.
851 AutoLoader can now be disabled with C<no AutoLoader;>.
855 B::Deparse has been significantly enhanced. It now can deparse almost
856 all of the standard test suite (so that the tests still succeed).
857 There is a make target "test.deparse" for trying this out.
861 Class::Struct can now define the classes in compile time.
865 Class::Struct now assigns the array/hash element if the accessor
866 is called with an array/hash element as the B<sole> argument.
870 Data::Dumper has now an option to sort hashes.
874 Data::Dumper has now an option to dump code references
879 DB_File now supports newer Berkeley DB versions, among
884 The English module can now be used without the infamous performance
887 use English '-no_performance_hit';
889 (Assuming, of course, that one doesn't need the troublesome variables
890 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
891 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
895 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
896 new-style constant dispatch section (see L<ExtUtils::Constant>).
897 This means that they will be more robust and hopefully faster.
901 File::Find now chdir()s correctly when chasing symbolic links.
905 File::Find now has pre- and post-processing callbacks. It also
906 correctly changes directories when chasing symbolic links. Callbacks
907 (naughtily) exiting with "next;" instead of "return;" now work.
911 File::Find is now (again) reentrant. It also has been made
916 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
917 prototype mismatch with CORE::glob().
921 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
922 the returned list of filenames.
926 Devel::Peek now has an interface for the Perl memory statistics
927 (this works only if you are using perl's malloc, and if you have
928 compiled with debugging).
932 IPC::Open3 now allows the use of numeric file descriptors.
936 IO::Socket has now atmark() method, which returns true if the socket
937 is positioned at the out-of-band mark. The method is also exportable
938 as a sockatmark() function.
942 IO::Socket::INET has support for ReusePort option (if your platform
943 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
944 you may want to prefer ReuseAddr.
948 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
949 that the operating system will make one up.)
953 use lib now works identically to @INC. Removing directories
954 with 'no lib' now works.
958 Math::BigFloat and Math::BigInt have undergone a full rewrite.
959 They are now magnitudes faster, and they support various
960 bignum libraries such as GMP and PARI as their backends.
964 Math::Complex handles inf, NaN etc., better.
968 Net::Ping has been enhanced. There is now "external" protocol which
969 uses Net::Ping::External module which runs external ping(1) and parses
970 the output. A version of Net::Ping::External is available in CPAN.
974 POSIX::sigaction() is now much more flexible and robust.
975 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
976 handlers, installing new handlers was not atomic.
980 In Safe the C<%INC> now localised in a Safe compartment so that
985 In SDBM_File on dosish platforms, some keys went missing because of
986 lack of support for files with "holes". A workaround for the problem
991 In Search::Dict one can now have a pre-processing hook for the
992 lines being searched.
996 The Shell module now has an OO interface.
1000 The Test module has been significantly enhanced.
1004 The vars pragma now supports declaring fully qualified variables.
1005 (Something that C<our()> does not and will not support.)
1009 The utf8:: name space (as in the pragma) provides various
1010 Perl-callable functions to provide low level access to Perl's
1011 internal Unicode representation. At the moment only length()
1012 has been implemented.
1016 =head1 Utility Changes
1022 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1027 F<emacs/e2ctags.pl> is now much faster.
1031 C<h2ph> now supports C trigraphs.
1035 C<h2xs> now produces a template README.
1039 C<h2xs> now uses C<Devel::PPort> for better portability between
1040 different versions of Perl.
1044 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
1045 newly created extensions that define constants. Since the new code is
1046 more correct (if you have two constants where the first one is a
1047 prefix of the second one, the first constant B<never> gets defined),
1048 less lossy (it uses integers for integer constant, as opposed to the
1049 old code that used floating point numbers even for integer constants),
1050 and slightly faster, you might want to consider regenerating your
1051 extension code (the new scheme makes regenerating easy).
1052 L<h2xs> now also supports C trigraphs.
1056 C<libnetcfg> has been added to configure the libnet.
1060 C<perlbug> is now much more robust. It also sends the bug report to
1061 perl.org, not perl.com.
1065 C<perlcc> has been rewritten and its user interface (that is,
1066 command line) is much more like that of the UNIX C compiler, cc.
1067 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1071 C<perlivp> is a new Installation Verification Procedure utility
1072 for running any time after installing Perl.
1076 C<pod2html> now allows specifying a cache directory.
1080 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1081 implementation of sed in Perl: you can use the sed functionality by
1082 using the C<psed> utility.)
1086 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1090 C<xsubpp> now supports OUT keyword.
1094 =head1 New Documentation
1100 perl56delta details the changes between the 5.005 release and the
1105 perlclib documents the internal replacements for standard C library
1106 functions. (Interesting only for extension writers and Perl core
1111 perldebtut is a Perl debugging tutorial.
1115 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1119 perlintro is a gentle introduction to Perl.
1123 perliol documents the internals of PerlIO with layers.
1127 perlmodstyle is a style guide for writing modules.
1131 perlnewmod tells about writing and submitting a new module.
1135 perlpacktut is a pack() tutorial.
1139 perlpod has been rewritten to be clearer and to record the best
1140 practices gathered over the years.
1144 perlpodspec is a more formal specification of the pod format,
1145 mainly of interest for writers of pod applications, not to
1146 people writing in pod.
1150 perlretut is a regular expression tutorial.
1154 perlrequick is a regular expressions quick-start guide.
1155 Yes, much quicker than perlretut.
1159 perltodo has been updated.
1163 perltootc has been renamed as perltooc (to not to conflict
1164 with perltoot in filesystems restricted to "8.3" names)
1168 perluniintro is an introduction to using Unicode in Perl
1169 (perlunicode is more of a reference)
1173 perlutil explains the command line utilities packaged with the Perl
1178 The following platform-specific documents are available before
1179 the installation as README.I<platform>, and after the installation
1182 perlaix perlamiga perlapollo perlbeos perlbs2000
1183 perlce perlcygwin perldgux perldos perlepoc perlhpux
1184 perlhurd perlmachten perlmacos perlmint perlmpeix
1185 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1186 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1192 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1193 confusion with the Perl POSIX module.
1197 The documentation for the WinCE platform is called "CE", to avoid
1198 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1202 =head1 Performance Enhancements
1208 map() could get pathologically slow when the result list it generates
1209 is larger than the source list. The performance has been improved for
1214 sort() has been changed to use primarily mergesort internally as
1215 opposed to the earlier quicksort. For very small lists this may
1216 result in slightly slower sorting times, but in general the speedup
1217 should be at least 20%. Additional bonuses are that the worst case
1218 behaviour of sort() is now better (in computer science terms it now
1219 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1220 worst-case run time behaviour), and that sort() is now stable
1221 (meaning that elements with identical keys will stay ordered as they
1222 were before the sort). See the C<sort> pragma for information.
1224 The story in more detail: suppose you want to serve yourself a little
1227 @digits = ( 3,1,4,1,5,9 );
1229 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1230 Which C<1> comes first is hard to know, since one C<1> looks pretty
1231 much like any other. You can regard this as totally trivial,
1232 or somewhat profound. However, if you just want to sort the even
1233 digits ahead of the odd ones, then what will
1235 sort { ($a % 2) <=> ($b % 2) } @digits;
1237 yield? The only even digit, C<4>, will come first. But how about
1238 the odd numbers, which all compare equal? With the quicksort algorithm
1239 used to implement Perl 5.6 and earlier, the order of ties is left up
1240 to the sort. So, as you add more and more digits of Pi, the order
1241 in which the sorted even and odd digits appear will change.
1242 and, for sufficiently large slices of Pi, the quicksort algorithm
1243 in Perl 5.8 won't return the same results even if reinvoked with the
1244 same input. The justification for this rests with quicksort's
1245 worst case behavior. If you run
1247 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1249 (something you might approximate if you wanted to merge two sorted
1250 arrays using sort), doubling $N doesn't just double the quicksort time,
1251 it I<quadruples> it. Quicksort has a worst case run time that can
1252 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1253 on patterns that may well arise in normal use. You won't notice this
1254 for small arrays, but you I<will> notice it with larger arrays,
1255 and you may not live long enough for the sort to complete on arrays
1256 of a million elements. So the 5.8 quicksort scrambles large arrays
1257 before sorting them, as a statistical defence against quadratic behaviour.
1258 But that means if you sort the same large array twice, ties may be
1259 broken in different ways.
1261 Because of the unpredictability of tie-breaking order, and the quadratic
1262 worst-case behaviour, quicksort was I<almost> replaced completely with
1263 a stable mergesort. I<Stable> means that ties are broken to preserve
1264 the original order of appearance in the input array. So
1266 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1268 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1269 appear in the output in the same order they appeared in the input.
1270 Mergesort has worst case O(NlogN) behaviour, the best value
1271 attainable. And, ironically, this mergesort does particularly
1272 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1273 in O(N) time. But quicksort was rescued at the last moment because
1274 it is faster than mergesort on certain inputs and platforms.
1275 For example, if you really I<don't> care about the order of even
1276 and odd digits, quicksort will run in O(N) time; it's very good
1277 at sorting many repetitions of a small number of distinct elements.
1278 The quicksort divide and conquer strategy works well on platforms
1279 with relatively small, very fast, caches. Eventually, the problem gets
1280 whittled down to one that fits in the cache, from which point it
1281 benefits from the increased memory speed.
1283 Quicksort was rescued by implementing a sort pragma to control aspects
1284 of the sort. The B<stable> subpragma forces stable behaviour,
1285 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1286 subpragmas are heavy-handed ways to select the underlying implementation.
1287 The leading C<_> is a reminder that these subpragmas may not survive
1288 beyond 5.8. More appropriate mechanisms for selecting the implementation
1289 exist, but they wouldn't have arrived in time to save quicksort.
1293 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1294 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1295 reasonably fast while producing a much better spread of values than
1296 the old hashing algorithm (originally by Chris Torek, later tweaked by
1297 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1298 all 3-char printable ASCII keys comes much closer to passing the
1299 DIEHARD random number generation tests. According to perlbench, this
1300 change has not affected the overall speed of Perl.
1304 unshift() should now be noticeably faster.
1308 =head1 Installation and Configuration Improvements
1310 =head2 Generic Improvements
1316 INSTALL now explains how you can configure Perl to use 64-bit
1317 integers even on non-64-bit platforms.
1321 Policy.sh policy change: if you are reusing a Policy.sh file
1322 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1323 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1324 them will now be changed to the new prefix, /foo/bar. (Previously
1325 only $prefix changed.) If you do not like this new behaviour,
1326 specify prefix, siteprefix, and vendorprefix explicitly.
1330 A new optional location for Perl libraries, otherlibdirs, is available.
1331 It can be used for example for vendor add-ons without disturbing Perl's
1332 own library directories.
1336 In many platforms the vendor-supplied 'cc' is too stripped-down to
1337 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1338 to be the case and 'cc' does not seem to be the GNU C compiler
1339 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1343 gcc needs to closely track the operating system release to avoid
1344 build problems. If Configure finds that gcc was built for a different
1345 operating system release than is running, it now gives a clearly visible
1346 warning that there may be trouble ahead.
1350 If binary compatibility with the 5.005 release is not wanted, Configure
1351 no longer suggests including the 5.005 modules in @INC.
1355 Configure C<-S> can now run non-interactively.
1359 Configure support for pdp11-style memory models has been removed due
1364 configure.gnu now works with options with whitespace in them.
1368 installperl now outputs everything to STDERR.
1372 $Config{byteorder} is now computed dynamically (this is more robust
1373 with "fat binaries" where an executable image contains binaries for
1374 more than one binary platform.)
1378 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1379 get appended to the $Config{archname} (also known as $^O) anymore.
1380 Instead, if you explicitly choose not to use perlio (Configure command
1381 line option -Uuseperlio), you will get "-stdio" appended.
1385 Another change related to the architecture name is that "-64all"
1386 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1387 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1391 In AFS installations one can configure the root of the AFS to be
1392 somewhere else than the default F</afs> by using the Configure
1393 parameter C<-Dafsroot=/some/where/else>.
1397 APPLLIB_EXP, a less-know configuration-time definition, has been
1398 documented. It can be used to prepend site-specific directories
1399 to Perl's default search path (@INC), see INSTALL for information.
1403 The version of Berkeley DB used when the Perl (and, presumably, the
1404 DB_File extension) was built is now available as
1405 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1406 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1407 DB_VERSION_PATCH_CFG> from C.
1411 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1412 has been documented in INSTALL.
1416 If you have CPAN access (either network or a local copy such as a
1417 CD-ROM) you can during specify extra modules to Configure to build and
1418 install with Perl using the -Dextras=... option. See INSTALL for
1423 In addition to config.over a new override file, config.arch, is
1424 available. That is supposed to be used by hints file writers for
1425 architecture-wide changes (as opposed to config.over which is for
1430 If your file system supports symbolic links you can build Perl outside
1431 of the source directory by
1433 mkdir /tmp/perl/build/directory
1434 cd /tmp/perl/build/directory
1435 sh /path/to/perl/source/Configure -Dmksymlinks ...
1437 This will create in /tmp/perl/build/directory a tree of symbolic links
1438 pointing to files in /path/to/perl/source. The original files are left
1439 unaffected. After Configure has finished you can just say
1443 and Perl will be built and tested, all in /tmp/perl/build/directory.
1447 For Perl developers several new make targets for profiling
1448 and debugging have been added, see L<perlhack>.
1454 Use of the F<gprof> tool to profile Perl has been documented in
1455 L<perlhack>. There is a make target called "perl.gprof" for
1456 generating a gprofiled Perl executable.
1460 If you have GCC 3, there is a make target called "perl.gcov" for
1461 creating a gcoved Perl executable for coverage analysis. See
1466 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1467 have been added, see L<perlhack> for more information about pixie and
1474 Guidelines of how to construct minimal Perl installations have
1475 been added to INSTALL.
1479 The Thread extension is now not built at all under ithreads
1480 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1481 Thread extension requires being Configured with C<-Duse5005threads>).
1483 But note that the Thread.pm interface is now shared by both
1488 =head2 New Or Improved Platforms
1490 For the list of platforms known to support Perl,
1491 see L<perlport/"Supported Platforms">.
1497 AIX dynamic loading should be now better supported.
1501 AIX should now work better with gcc, threads, and 64-bitness. Also the
1502 long doubles support in AIX should be better now. See L<perlaix>.
1506 After a long pause, AmigaOS has been verified to be happy with Perl.
1510 AtheOS (http://www.atheos.cx/) is a new platform.
1514 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1518 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1522 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1523 have been regained. Many test suite tests still fail and the
1524 co-existence of Unicode and EBCDIC isn't quite settled, but the
1525 situation is much better than with Perl 5.6. See L<perlos390>,
1526 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1530 Building perl with -Duseithreads or -Duse5005threads now works under
1531 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1532 need a thread library package installed. See README.hpux.
1536 MacOS Classic (MacPerl has of course been available since
1537 perl 5.004 but now the source code bases of standard Perl
1538 and MacPerl have been synchronised)
1542 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1543 filesystems. (The case-insensitivity confused the Perl build process.)
1547 NCR MP-RAS is now supported.
1551 NetWare from Novell is now supported. See L<perlnetware>.
1555 NonStop-UX is now supported.
1559 NEC SUPER-UX is now supported.
1563 Amdahl UTS UNIX mainframe platform is now supported.
1567 WinCE is now supported. See L<perlce>.
1571 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1572 support for dynamic loading. This is not selected by default,
1573 however, you must specify -Dusedl in the arguments of Configure.
1577 =head1 Selected Bug Fixes
1579 Numerous memory leaks and uninitialized memory accesses have been
1580 hunted down. Most importantly anonymous subs used to leak quite
1587 The autouse pragma didn't work for Multi::Part::Function::Names.
1591 caller() could cause core dumps in certain situations. Carp was sometimes
1592 affected by this problem.
1596 chop(@list) in list context returned the characters chopped in
1597 reverse order. This has been reversed to be in the right order.
1601 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1602 when building the Perl binary. The only exception to this is SunOS 4.x,
1607 The behaviour of non-decimal but numeric string constants such as
1608 "0x23" was platform-dependent: in some platforms that was seen as 35,
1609 in some as 0, in some as a floating point number (don't ask). This
1610 was caused by Perl using the operating system libraries in a situation
1611 where the result of the string to number conversion is undefined: now
1612 Perl consistently handles such strings as zero in numeric contexts.
1616 The order of DESTROYs has been made more predictable.
1620 Several debugger fixes: exit code now reflects the script exit code,
1621 condition C<"0"> now treated correctly, the C<d> command now checks
1622 line number, the C<$.> no longer gets corrupted, all debugger output
1623 now goes correctly to the socket if RemotePort is set.
1627 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1628 when statically building extensions into perl. This has been corrected.
1632 L<dprofpp> -R didn't work.
1636 C<*foo{FORMAT}> now works.
1639 Infinity is now recognized as a number.
1643 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1644 the Tk extension with 5.6.0.)
1648 Lexicals I: lexicals outside an eval "" weren't resolved
1649 correctly inside a subroutine definition inside the eval "" if they
1650 were not already referenced in the top level of the eval""ed code.
1654 Lexicals II: lexicals leaked at file scope into subroutines that
1655 were declared before the lexicals.
1659 Lexical warnings now propagating correctly between scopes
1660 and into C<eval "...">.
1664 C<use warnings qw(FATAL all)> did not work as intended. This has been
1669 warnings::enabled() now reports the state of $^W correctly if the caller
1670 isn't using lexical warnings.
1674 Line renumbering with eval and C<#line> now works.
1678 Fixed numerous memory leaks, especially in eval "".
1682 mkdir() now ignores trailing slashes in the directory name,
1683 as mandated by POSIX.
1687 Some versions of glibc have a broken modfl(). This affects builds
1688 with C<-Duselongdouble>. This version of Perl detects this brokenness
1689 and has a workaround for it. The glibc release 2.2.2 is known to have
1690 fixed the modfl() bug.
1694 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1695 return 27406, instead of 27047).
1699 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1700 more compatible with 5.005. Infinity is now recognised as a number.
1704 Numeric conversions did not recognize changes in the string value
1705 properly in certain circumstances.
1709 Attributes (like :shared) didn't work with our().
1713 our() variables will not cause "will not stay shared" warnings.
1717 "our" variables of the same name declared in two sibling blocks
1718 resulted in bogus warnings about "redeclaration" of the variables.
1719 The problem has been corrected.
1723 pack "Z" now correctly terminates the string with "\0".
1727 Fix password routines which in some shadow password platforms
1728 (e.g. HP-UX) caused getpwent() to return every other entry.
1732 The PERL5OPT environment variable (for passing command line arguments
1733 to Perl) didn't work for more than a single group of options.
1737 PERL5OPT with embedded spaces didn't work.
1741 printf() no longer resets the numeric locale to "C".
1745 C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1749 pos() did not return the correct value within s///ge in earlier
1750 versions. This is now handled correctly.
1754 Printing quads (64-bit integers) with printf/sprintf now works
1755 without the q L ll prefixes (assuming you are on a quad-capable platform).
1759 Regular expressions on references and overloaded scalars now work.
1763 Right-hand side magic (GMAGIC) could in many cases such as string
1764 concatenation be invoked too many times.
1768 scalar() now forces scalar context even when used in void context.
1772 SOCKS support is now much more robust.
1776 sort() arguments are now compiled in the right wantarray context
1777 (they were accidentally using the context of the sort() itself).
1778 The comparison block is now run in scalar context, and the arguments
1779 to be sorted are always provided list context.
1783 Changed the POSIX character class C<[[:space:]]> to include the (very
1784 rarely used) vertical tab character. Added a new POSIX-ish character
1785 class C<[[:blank:]]> which stands for horizontal whitespace
1786 (currently, the space and the tab).
1790 The tainting behaviour of sprintf() has been rationalized. It does
1791 not taint the result of floating point formats anymore, making the
1792 behaviour consistent with that of string interpolation.
1796 Some cases of inconsistent taint propagation (such as within hash
1797 values) have been fixed.
1801 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1802 of simple pattern matches. These are now handled better.
1806 Regular expression debug output (whether through C<use re 'debug'>
1807 or via C<-Dr>) now looks better.
1811 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
1816 Use of $& could trigger a core dump under some situations. This
1821 The regular expression captured submatches ($1, $2, ...) are now
1822 more consistently unset if the match fails, instead of leaving false
1823 data lying around in them.
1827 readline() on files opened in "slurp" mode could return an extra "" at
1828 the end in certain situations. This has been corrected.
1832 Autovivification of symbolic references of special variables described
1833 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
1838 Sys::Syslog ignored the C<LOG_AUTH> constant.
1842 All but the first argument of the IO syswrite() method are now optional.
1846 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1847 in multiple threads simultaneously are now thread-safe.
1851 Tie::ARRAY SPLICE method was broken.
1855 Allow read-only string on left hand side of non-modifying tr///.
1859 Several Unicode fixes.
1865 BOMs (byte order marks) in the beginning of Perl files
1866 (scripts, modules) should now be transparently skipped.
1867 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1871 The character tables have been updated to Unicode 3.1.1.
1875 Comparing with utf8 data does not magically upgrade non-utf8 data
1880 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1884 Concatenation with the C<.> operator or via variable interpolation,
1885 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1886 substitution with C<s///>, single-quoted UTF8, should now work.
1890 The C<tr///> operator now works. Note that the C<tr///CU>
1891 functionality has been removed (but see pack('U0', ...)).
1895 C<eval "v200"> now works.
1899 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
1900 This has been corrected.
1904 Zero entries were missing from the Unicode classes like C<IsDigit>.
1910 Large unsigned numbers (those above 2**31) could sometimes lose their
1911 unsignedness, causing bogus results in arithmetic operations.
1915 =head2 Platform Specific Changes and Fixes
1923 Perl now works on post-4.0 BSD/OSes.
1929 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
1935 Numerous updates; currently synchronised with Cygwin 1.1.4.
1939 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1945 EPOC update after Perl 5.6.0. See README.epoc.
1951 Perl now works on post-3.0 FreeBSDs.
1957 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1963 Numerous compilation flag and hint enhancements; accidental mixing
1964 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1974 Long doubles should now work (see INSTALL).
1978 Linux previously had problems related to sockaddrlen when using
1979 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1987 Compilation of the standard Perl distribution in MacOS Classic should
1988 now work if you have the Metrowerks development environment and
1989 the missing Mac-specific toolkit bits. Contact the macperl mailing
1996 MPE/iX update after Perl 5.6.0. See README.mpeix.
2002 Perl now works on NetBSD/sparc.
2008 Now works with usethreads (see INSTALL).
2014 64-bitness using the Sun Workshop compiler now works.
2018 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2020 The operating system version letter now recorded in $Config{osvers}.
2021 Allow compiling with gcc (previously explicitly forbidden). Compiling
2022 with gcc still not recommended because buggy code results, even with
2029 Fixed various alignment problems that lead into core dumps either
2030 during build or later; no longer dies on math errors at runtime;
2031 now using full quad integers (64 bits), previously was using
2032 only 46 bit integers for speed.
2038 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2039 (see INSTALL); now works with Perl's malloc.
2041 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2042 unimplemented. It now works as documented.
2044 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2045 was that a pid of -1 would cause a wildcard search of all processes on
2046 the system. The most significant enhancement is that we can now
2047 usually get the completion status of a terminated process.
2049 POSIX-style signals are now emulated much better on VMS versions prior
2052 The C<system> function and backticks operator have improved
2053 functionality and better error handling.
2063 accept() no longer leaks memory.
2067 Borland C++ v5.5 is now a supported compiler that can build Perl.
2068 However, the generated binaries continue to be incompatible with those
2069 generated by the other supported compilers (GCC and Visual C++).
2073 Better chdir() return value for a non-existent directory.
2077 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2081 New %ENV entries now propagate to subprocesses.
2085 Current directory entries in %ENV are now correctly propagated to child
2090 $ENV{LIB} now used to search for libs under Visual C.
2094 fork() emulation has been improved in various ways, but still continues
2095 to be experimental. See L<perlfork> for known bugs and caveats.
2099 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2103 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2104 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2108 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2112 The makefiles now provide a single switch to bulk-enable all the features
2113 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2117 Allow REG_EXPAND_SZ keys in the registry.
2121 Can now send() from all threads, not just the first one.
2125 Fake signal handling reenabled, bugs and all.
2129 %SIG has been enabled under USE_ITHREADS, but its use is completely
2130 unsupported under all configurations.
2134 Less stack reserved per thread so that more threads can run
2135 concurrently. (Still 16M per thread.)
2139 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
2140 (works better when perl is running as service).
2144 Better UNC path handling under ithreads.
2148 wait(), waitpid() and backticks now return the correct exit status under
2153 winsock handle leak fixed.
2159 =head1 New or Changed Diagnostics
2165 All regular expression compilation error messages are now hopefully
2166 easier to understand both because the error message now comes before
2167 the failed regex and because the point of failure is now clearly
2168 marked by a C<E<lt>-- HERE> marker.
2172 The various "opened only for", "on closed", "never opened" warnings
2173 drop the C<main::> prefix for filehandles in the C<main> package,
2174 for example C<STDIN> instead of C<main::STDIN>.
2178 The "Unrecognized escape" warning has been extended to include C<\8>,
2179 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2183 Two new debugging options have been added: if you have compiled your
2184 Perl with debugging, you can use the -DT and -DR options to trace
2185 tokenising and to add reference counts to displaying variables,
2190 If an attempt to use a (non-blessed) reference as an array index
2191 is made, a warning is given.
2195 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2196 now give a warning. This may be a problem for generated and evaled
2201 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2202 using the C<"C"> format you will get an optional warning. Similarly
2203 for the C<"c"> format and a number less than -128 or more than 127.
2207 Certain regex modifiers such as C<(?o)> make sense only if applied to
2208 the entire regex. You will an optional warning if you try to do otherwise.
2212 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2213 has been deprecated for a while. Now you will get an optional warning.
2217 =head1 Changed Internals
2223 perlapi.pod (a companion to perlguts) now attempts to document the
2228 You can now build a really minimal perl called microperl.
2229 Building microperl does not require even running Configure;
2230 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2231 many assumptions, some of which may be too bold; the resulting
2232 executable may crash or otherwise misbehave in wondrous ways.
2233 For careful hackers only.
2237 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2238 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2239 interfaces to the publicised API. For the full list of the available
2240 APIs see L<perlapi>.
2244 Made possible to propagate customised exceptions via croak()ing.
2248 Now xsubs can have attributes just like subs. (Well, at least the
2249 built-in attributes.)
2253 dTHR and djSP have been obsoleted; the former removed (because it's
2254 a no-op) and the latter replaced with dSP.
2258 PERL_OBJECT has been completely removed.
2262 The MAGIC constants (e.g. C<'P'>) have been macrofied
2263 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2264 and maintainability.
2268 The regex compiler now maintains a structure that identifies nodes in
2269 the compiled bytecode with the corresponding syntactic features of the
2270 original regex expression. The information is attached to the new
2271 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2272 complete information.
2276 The C code has been made much more C<gcc -Wall> clean. Some warning
2277 messages still remain in some platforms, so if you are compiling with
2278 gcc you may see some warnings about dubious practices. The warnings
2279 are being worked on.
2283 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2287 Documentation on how to use the Perl source repository has been added
2288 to F<Porting/repository.pod>.
2292 There are now several profiling make targets.
2296 =head1 Security Vulnerability Closed
2298 (This change was already made in 5.7.0 but bears repeating here.)
2300 A potential security vulnerability in the optional suidperl component
2301 of Perl was identified in August 2000. suidperl is neither built nor
2302 installed by default. As of November 2001 the only known vulnerable
2303 platform is Linux, most likely all Linux distributions. CERT and
2304 various vendors and distributors have been alerted about the vulnerability.
2305 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2306 for more information.
2308 The problem was caused by Perl trying to report a suspected security
2309 exploit attempt using an external program, /bin/mail. On Linux
2310 platforms the /bin/mail program had an undocumented feature which
2311 when combined with suidperl gave access to a root shell, resulting in
2312 a serious compromise instead of reporting the exploit attempt. If you
2313 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2314 suidperl is not installed, you are safe.
2316 The exploit attempt reporting feature has been completely removed from
2317 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2318 from all the Perl 5.7 releases), so that particular vulnerability
2319 isn't there anymore. However, further security vulnerabilities are,
2320 unfortunately, always possible. The suidperl functionality is most
2321 probably going to be removed in Perl 5.10. In any case, suidperl
2322 should only be used by security experts who know exactly what they are
2323 doing and why they are using suidperl instead of some other solution
2324 such as sudo (see http://www.courtesan.com/sudo/).
2328 Several new tests have been added, especially for the F<lib>
2329 subsection. There are now about 34 000 individual tests (spread over
2330 about 530 test scripts), in the regression suite (5.6.1 has about
2331 11700 tests, in 258 test scripts) Many of the new tests are introduced
2332 by the new modules, but still in general Perl is now more thoroughly
2335 Because of the large number of tests, running the regression suite
2336 will take considerably longer time than it used to: expect the suite
2337 to take up to 4-5 times longer to run than in perl 5.6. In a really
2338 fast machine you can hope to finish the suite in about 5 minutes
2341 The tests are now reported in a different order than in earlier Perls.
2342 (This happens because the test scripts from under t/lib have been moved
2343 to be closer to the library/extension they are testing.)
2345 =head1 Known Problems
2353 In AIX 4.2 Perl extensions that use C++ functions that use statics
2354 may have problems in that the statics are not getting initialized.
2355 In newer AIX releases this has been solved by linking Perl with
2356 the libC_r library, but unfortunately in AIX 4.2 the said library
2357 has an obscure bug where the various functions related to time
2358 (such as time() and gettimeofday()) return broken values, and
2359 therefore in AIX 4.2 Perl is not linked against the libC_r.
2363 vac 5.0.0.0 May Produce Buggy Code For Perl
2365 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2366 resulting in few random tests failing, but when the failing tests
2367 are run by hand, they succeed. We suggest upgrading to at least
2368 vac version 5.0.1.0, that has been known to compile Perl correctly.
2369 "lslpp -L|grep vac.C" will tell you the vac version.
2373 =head2 Amiga Perl Invoking Mystery
2375 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2376 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2377 known but the current suspect is the F<ixemul> library.
2379 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2381 Don't panic. Read INSTALL 'make test' section instead.
2383 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2385 The subtests 11 and 12 sometimes fail and sometimes work.
2387 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2389 The lib/io_multihomed test may hang in HP-UX if Perl has been
2390 configured to be 64-bit. Because other 64-bit platforms do not hang in
2391 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2392 test attempts to create and connect to "multihomed" sockets (sockets
2393 which have multiple IP addresses).
2395 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2397 If perl is configured with -Duse64bitall, the successful result of the
2398 subtest 10 of lib/posix may arrive before the successful result of the
2399 subtest 9, which confuses the test harness so much that it thinks the
2402 =head2 Linux With Sfio Fails op/misc Test 48
2408 The following tests are known to fail:
2410 Failed Test Stat Wstat Total Fail Failed List of Failed
2411 -------------------------------------------------------------------------
2412 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2413 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2414 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2415 ../lib/warnings.t 450 1 0.22% 316
2419 OS/390 has rather many test failures but the situation is actually
2420 better than it was in 5.6.0, it's just that so many new modules and
2421 tests have been added.
2423 Failed Test Stat Wstat Total Fail Failed List of Failed
2424 -----------------------------------------------------------------------------
2425 ../ext/B/Deparse.t 14 1 7.14% 14
2426 ../ext/B/Showlex.t 1 1 100.00% 1
2427 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2429 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2430 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2431 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2432 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2433 ../lib/warnings.t 434 1 0.23% 75
2434 ../lib/ExtUtils.t 27 1 3.70% 25
2435 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2436 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2437 ../lib/User/pwent.t 9 1 11.11% 4
2438 op/pat.t 660 6 0.91% 242-243 424-425
2440 op/split.t 0 9 ?? ?? % ??
2441 op/taint.t 174 3 1.72% 156 162 168
2442 op/tr.t 70 3 4.29% 50 58-59
2443 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2445 =head2 op/sprintf tests 129 and 130
2447 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2448 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2449 The failing platforms do not comply with the ANSI C Standard, line
2450 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2451 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2452 the printf format "%.0f", most often they produce "0" and "-0".)
2454 =head2 Failure of Thread tests
2456 B<Note that support for 5.005-style threading remains experimental
2457 and practically unsupported.>
2459 The following tests are known to fail due to fundamental problems in
2460 the 5.005 threading implementation. These are not new failures--Perl
2461 5.005_0x has the same bugs, but didn't have these tests.
2463 ext/List/Util/t/first 2
2465 ext/Thread/thr5005 19-20
2467 These failures are unlikely to get fixed.
2475 ext/POSIX/sigaction subtests 6 and 13 may fail.
2479 lib/ExtUtils may spuriously claim that subtest 28 failed,
2480 which is interesting since the test only has 27 tests.
2484 Numerous numerical test failures
2486 op/numconvert 209,210,217,218
2488 ext/Time/HiRes/HiRes 9
2489 lib/Math/BigInt/t/bigintpm 1145
2492 These tests fail because of yet unresolved floating point inaccuracies.
2498 There are a few known test failures, see L<perluts>.
2502 There is one known test failure with a default configuration:
2504 [.run]switches..........................FAILED on test 1
2508 In multi-CPU boxes there are some problems with the I/O buffering:
2509 some output may appear twice.
2511 =head2 Localising a Tied Variable Leaks Memory
2514 tie my %tie_hash => 'Tie::StdHash';
2518 local($tie_hash{Foo}) = 1; # leaks
2520 Code like the above is known to leak memory every time the local()
2523 =head2 Localising Tied Arrays and Hashes Is Broken
2527 doesn't work as one would expect: the old value is restored
2530 =head2 Self-tying of Arrays and Hashes Is Forbidden
2532 Self-tying of arrays and hashes is broken in rather deep and
2533 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2534 frustrated at the mysterious results (core dumps, most often) it is
2535 for now forbidden (you will get a fatal error even from an attempt).
2537 =head2 Building Extensions Can Fail Because Of Largefiles
2539 Some extensions like mod_perl are known to have issues with
2540 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2541 default to 64 bits wide, where supported. Modules may fail to compile
2542 at all or compile and work incorrectly. Currently there is no good
2543 solution for the problem, but Configure now provides appropriate
2544 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2545 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2546 having problems can try configuring themselves without the
2547 largefileness. This is admittedly not a clean solution, and the
2548 solution may not even work at all. One potential failure is whether
2549 one can (or, if one can, whether it's a good idea) link together at
2550 all binaries with different ideas about file offsets, all this is
2553 =head2 Unicode Support on EBCDIC Still Spotty
2555 Though mostly working, Unicode support still has problem spots on
2556 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2557 regular expression constructs for code points less than 256: the
2558 pP are testing for Unicode code points, not knowing about EBCDIC.
2560 =head2 The Compiler Suite Is Still Experimental
2562 The compiler suite is slowly getting better but it continues to be
2563 highly experimental. Use in production environments is discouraged.
2565 =head2 The Long Double Support Is Still Experimental
2567 The ability to configure Perl's numbers to use "long doubles",
2568 floating point numbers of hopefully better accuracy, is still
2569 experimental. The implementations of long doubles are not yet
2570 widespread and the existing implementations are not quite mature
2571 or standardised, therefore trying to support them is a rare
2572 and moving target. The gain of more precision may also be offset
2573 by slowdown in computations (more bits to move around, and the
2574 operations are more likely to be executed by less optimised
2577 =head2 Seen In Perl 5.7 But Gone Now
2579 Some modules were seen in the Perl 5.7 development releases
2580 but are not present in 5.8.0.
2586 C<Attribute::Handlers> was removed because the implementation of C<my>
2587 variable attributes changed so much that the Attribute::Handlers will
2588 require a major rewrite. (This means that you can't use
2589 Attribute::Handler 0.76 with Perl 5.8.0.)
2593 C<Time::Piece> (previously known as C<Time::Object>) was removed
2594 because it was felt that it didn't have enough value in it to be a
2595 core module. It is still a useful module, though, and is available
2600 =head1 Reporting Bugs
2602 If you find what you think is a bug, you might check the articles
2603 recently posted to the comp.lang.perl.misc newsgroup and the perl
2604 bug database at http://bugs.perl.org. There may also be
2605 information at http://www.perl.com/, the Perl Home Page.
2607 If you believe you have an unreported bug, please run the B<perlbug>
2608 program included with your release. Be sure to trim your bug down
2609 to a tiny but sufficient test case. Your bug report, along with the
2610 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2611 analysed by the Perl porting team.
2615 The F<Changes> file for exhaustive details on what changed.
2617 The F<INSTALL> file for how to build Perl.
2619 The F<README> file for general stuff.
2621 The F<Artistic> and F<Copying> files for copyright information.
2625 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.