3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release and the
10 =head1 Incompatible Changes
12 =head2 64-bit platforms and malloc
14 If your pointers are 64 bits wide, the Perl malloc is no more being
15 used because it simply does not work with 8-byte pointers. Also,
16 usually the system mallocs on such platforms are much better optimized
17 for such large memory models than the Perl malloc. Such platforms
18 include 64-bit Alpha, MIPS, HPPA, PPC, and Sparc.
20 =head2 AIX Dynaloading
22 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
23 dlopen interface of AIX instead of the old emulated interface. This
24 change will probably break backward compatibility with compiled
25 modules. The change was made to make Perl more compliant with other
26 applications like modperl which are using the AIX native interface.
28 =head2 Socket Extension Dynamic in VMS
30 The Socket extension is now dynamically loaded instead of being
31 statically built in. This may or may not be a problem with ancient
32 TCP/IP stacks of VMS: we do not know since we weren't able to test
33 Perl in such configurations.
35 =head2 Different Definition of the Unicode Character Classes \p{In...}
37 As suggested by the Unicode consortium, the Unicode character classes
38 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
39 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
40 constructs are used. This has changed the definition of some of those
43 The difference between scripts and blocks is that scripts are the
44 glyphs used by a language or a group of languages, while the blocks
45 are more artificial groupings of 256 characters based on the Unicode
48 In general this change results in more inclusive Unicode character
49 classes, but changes to the other direction also do take place:
50 for example while the script C<Latin> includes all the Latin
51 characters and their various diacritic-adorned versions, it
52 does not include the various punctuation or digits (since they
53 are not solely C<Latin>).
55 Changes in the character class semantics may have happened if a script
56 and a block happen to have the same name, for example C<Hebrew>.
57 In such cases the script wins and C<\p{InHebrew}> now means the script
58 definition of Hebrew. The block definition in still available,
59 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
60 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
61 of affected character classes, see L<perlunicode/Blocks>.
63 =head2 Perl Parser Stress Tested
65 The Perl parser has been stress tested using both random input and
66 Markov chain input and the few found crashes and lockups have been
71 The current user-visible implementation of pseudo-hashes (the weird
72 use of the first array element) is deprecated starting from Perl 5.8.0
73 and will be removed in Perl 5.10.0, and the feature will be
74 implemented differently. Not only is the current interface rather
75 ugly, but the current implementation slows down normal array and hash
76 use quite noticeably. The C<fields> pragma interface will remain
79 The syntaxes C<@a->[...]> and C<@h->{...}> have now been deprecated.
81 After years of trying the suidperl is considered to be too complex to
82 ever be considered truly secure. The suidperl functionality is likely
83 to be removed in a future release.
85 The C<package;> syntax (C<package> without an argument has been
86 deprecated. Its semantics were never that clear and its
87 implementation even less so. If you have used that feature to
88 disallow all but fully qualified variables, C<use strict;> instead.
94 The semantics of bless(REF, REF) were unclear and until someone proves
95 it to make some sense, it is forbidden.
99 A reference to a reference now stringify as "REF(0x81485ec)" instead
100 of "SCALAR(0x81485ec)" in order to be more consistent with the return
105 The very dusty examples in the eg/ directory have been removed.
106 Suggestions for new shiny examples welcome but the main issue is that
107 the examples need to be documented, tested and (most importantly)
112 The obsolete chat2 library that should never have been allowed
113 to escape the laboratory has been decommissioned.
117 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
118 recognised but now cause fatal errors. The previous behaviour of
119 ignoring them by default and warning if requested was unacceptable
120 since it, in a way, falsely promised that the features could be used.
124 The (bogus) escape sequences \8 and \9 now give an optional warning
125 ("Unrecognized escape passed through"). There is no need to \-escape
130 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
131 In future releases this may become a fatal error.
135 The long deprecated uppercase aliases for the string comparison
136 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
140 The regular expression captured submatches ($1, $2, ...) are now
141 more consistently unset if the match fails, instead of leaving false
142 data lying around in them.
146 The tr///C and tr///U features have been removed and will not return;
147 the interface was a mistake. Sorry about that. For similar
148 functionality, see pack('U0', ...) and pack('C0', ...).
152 Although "you shouldn't do that", it was possible to write code that
153 depends on Perl's hashed key order (Data::Dumper does this). The new
154 algorithm "One-at-a-Time" produces a different hashed key order.
155 More details are in L</"Performance Enhancements">.
159 The list of filenames from glob() (or <...>) is now by default sorted
160 alphabetically to be csh-compliant. (bsd_glob() does still sort platform
161 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
165 =head1 Core Enhancements
167 =head2 PerlIO is Now The Default
173 IO is now by default done via PerlIO rather than system's "stdio".
174 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
175 handle's behaviour. Layers can be specified at open time via 3-arg
178 open($fh,'>:crlf :utf8', $path) || ...
180 or on already opened handles via extended C<binmode>:
182 binmode($fh,':encoding(iso-8859-7)');
184 The built-in layers are: unix (low level read/write), stdio (as in
185 previous Perls), perlio (re-implementation of stdio buffering in a
186 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
187 but available on any platform). A mmap layer may be available if
188 platform supports it (mostly UNIXes).
190 Layers to be applied by default may be specified via the 'open' pragma.
192 See L</"Installation and Configuration Improvements"> for the effects
193 of PerlIO on your architecture name.
197 File handles can be marked as accepting Perl's internal encoding of Unicode
198 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
200 open($fh,">:utf8","Uni.txt");
202 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
203 for you since it's not UTF-8 what you will be getting but instead
204 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
205 http://www.unicode.org/unicode/reports/tr16/ for more information.
206 In future releases this naming may change.
210 File handles can translate character encodings from/to Perl's internal
211 Unicode form on read/write via the ":encoding()" layer.
215 File handles can be opened to "in memory" files held in Perl scalars via:
217 open($fh,'>', \$variable) || ...
221 Anonymous temporary files are available without need to
222 'use FileHandle' or other module via
224 open($fh,"+>", undef) || ...
226 That is a literal undef, not an undefined value.
230 The list form of C<open> is now implemented for pipes (at least on UNIX):
232 open($fh,"-|", 'cat', '/etc/motd')
234 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
239 =head2 Signals Are Now Safe
241 Perl used to be fragile in that signals arriving at inopportune moments
242 could corrupt Perl's internal state. Now Perl postpones handling of
243 signals until it's safe.
245 =head2 Unicode Overhaul
247 Unicode in general should be now much more usable than in Perl 5.6.0
248 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
249 regular expressions should work now, Unicode in tr/// should work now,
250 Unicode in I/O should work now.
256 The Unicode Character Database coming with Perl has been upgraded
257 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
261 For developers interested in enhancing Perl's Unicode capabilities:
262 almost all the UCD files are included with the Perl distribution in
263 the lib/unicore subdirectory. The most notable omission, for space
264 considerations, is the Unihan database.
268 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
269 added. "Blank" is like C isblank(), that is, it contains only
270 "horizontal whitespace" (the space character is, the newline isn't),
271 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
272 isn't, since that includes the vertical tabulator character, whereas
277 =head2 Understanding of Numbers
279 In general a lot of fixing has happened in the area of Perl's
280 understanding of numbers, both integer and floating point. Since in
281 many systems the standard number parsing functions like C<strtoul()>
282 and C<atof()> seem to have bugs, Perl tries to work around their
283 deficiencies. This results hopefully in more accurate numbers.
285 Perl now tries internally to use integer values in numeric conversions
286 and basic arithmetics (+ - * /) if the arguments are integers, and
287 tries also to keep the results stored internally as integers.
288 This change leads into often slightly faster and always less lossy
289 arithmetics. (Previously Perl always preferred floating point numbers
292 =head2 Miscellaneous Enhancements
298 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
299 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
303 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
304 in multiple arguments.)
308 END blocks are now run even if you exit/die in a BEGIN block.
309 Internally, the execution of END blocks is now controlled by
310 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
311 behaviour for Perl embedders. This will default in 5.10. See
316 Formats now support zero-padded decimal fields.
320 Lvalue subroutines can now return C<undef> in list context.
324 A new special regular expression variable has been introduced:
325 C<$^N>, which contains the most-recently closed group (submatch).
329 C<no Module;> now works even if there is no "sub unimport" in the Module.
333 The numerical comparison operators return C<undef> if either operand
334 is a NaN. Previously the behaviour was unspecified.
338 The following builtin functions are now overridable: each(), keys(),
339 pop(), push(), shift(), splice(), unshift().
343 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
347 my __PACKAGE__ $obj now works.
351 The printf() and sprintf() now support parameter reordering using the
352 C<%\d+\$> and C<*\d+\$> syntaxes. For example
354 print "%2\$s %1\$s\n", "foo", "bar";
356 will print "bar foo\n"; This feature helps in writing
357 internationalised software.
361 prototype(\&) is now available.
365 prototype(\[$@%&]) is now available to implicitly create references
366 (useful for example if you want to emulate the tie() interface).
370 UNTIE method is now recognised.
374 L<utime> now supports C<utime undef, undef, @files> to change the
375 file timestamps to the current time.
379 The rules for allowing underscores (underbars) in numeric constants
380 have been relaxed and simplified: now you can have an underscore
381 simply B<between digits>.
385 =head1 Modules and Pragmata
387 =head2 New Modules and Pragmata
393 C<Attribute::Handlers> allows a class to define attribute handlers.
396 use Attribute::Handlers;
397 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
399 # later, in some package using or inheriting from MyPack...
401 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
403 Both variables and routines can have attribute handlers. Handlers can
404 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
405 exact compilation phase (BEGIN, CHECK, INIT, or END).
409 B<B::Concise> is a new compiler backend for walking the Perl syntax
410 tree, printing concise info about ops, from Stephen McCamant. The
411 output is highly customisable. See L<B::Concise>.
415 C<Class::ISA> for reporting the search path for a class's ISA tree,
416 by Sean Burke, has been added. See L<Class::ISA>.
420 C<Cwd> has now a split personality: if possible, an XS extension is
421 used, (this will hopefully be faster, more secure, and more robust)
422 but if not possible, the familiar Perl implementation is used.
426 C<Devel::PPPort>, originally from Kenneth Albanowski and now
427 maintained by Paul Marquess, has been added. It is primarily used
428 by C<h2xs> to enhance portability of of XS modules between different
433 C<Digest>, frontend module for calculating digests (checksums), from
434 Gisle Aas, has been added. See L<Digest>.
438 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
439 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
441 use Digest::MD5 'md5_hex';
443 $digest = md5_hex("Thirsty Camel");
445 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
447 NOTE: the C<MD5> backward compatibility module is deliberately not
448 included since its further use is discouraged.
452 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
453 between different character encodings. Support for Unicode,
454 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
455 compiled in to the module. Several other encodings (like Japanese,
456 Chinese, and MacIntosh encodings) are included and will be loaded at
457 runtime. See L<Encode>.
459 Any encoding supported by Encode module is also available to the
460 ":encoding()" layer if PerlIO is used.
464 C<I18N::Langinfo> can be use to query locale information.
465 See L<I18N::Langinfo>.
469 C<I18N::LangTags> has functions for dealing with RFC3066-style
470 language tags, by Sean Burke. See <I18N::LangTags>.
474 C<ExtUtils::Constant> is a new tool for extension writers for
475 generating XS code to import C header constants, by Nicholas Clark.
476 See L<ExtUtils::Constant>.
480 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
481 from Damian Conway. See L<Filter::Simple>.
487 use Filter::Simple sub {
488 while (my ($from, $to) = splice @_, 0, 2) {
497 use MyFilter qr/red/ => 'green';
499 print "red\n"; # this code is filtered, will print "green\n"
500 print "bored\n"; # this code is filtered, will print "bogreen\n"
504 print "red\n"; # this code is not filtered, will print "red\n"
508 C<File::Temp> allows one to create temporary files and directories in
509 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
513 C<Filter::Util::Call> provides you with the framework to write
514 I<Source Filters> in Perl, from Paul Marquess. For most uses the
515 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
519 L<libnet> is a collection of perl5 modules related to network
520 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
521 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
523 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
527 C<List::Util> is a selection of general-utility list subroutines, like
528 sum(), min(), first(), and shuffle(), by Graham barr. See L<List::Util>.
532 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
533 C<Locale::Language>, from Neil Bowers, have been added. They provide the
534 codes for various locale standards, such as "fr" for France, "usd" for
535 US Dollar, and "jp" for Japanese.
539 $country = code2country('jp'); # $country gets 'Japan'
540 $code = country2code('Norway'); # $code gets 'no'
542 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
543 and L<Locale::Language>.
547 C<Locale::Maketext> is localization framework from Sean Burke. See
548 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
549 article about software localization, originally published in The Perl
550 Journal #13, republished here with kind permission.
554 C<Memoize> can make your functions faster by trading space for time,
555 from Mark-Jason Dominus. See L<Memoize>.
559 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
560 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
565 $encoded = encode_base64('Aladdin:open sesame');
566 $decoded = decode_base64($encoded);
568 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
574 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
575 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
576 Extensions)>, from Gisle Aas.
578 use MIME::QuotedPrint;
580 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
581 $decoded = decode_qp($encoded);
583 print $encoded, "\n"; # "Smiley in Unicode: =263A"
585 MIME::QuotedPrint has been enhanced to provide the basic methods
586 necessary to use it with PerlIO::Via as in :
588 use MIME::QuotedPrint;
589 open($fh,">Via(MIME::QuotedPrint)",$path)
591 See L<MIME::QuotedPrint>.
595 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
600 C<open> is a new pragma for setting the default I/O disciplines
605 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
606 Perl scalars as discussed above, from Nick Ing-Simmons. It also
607 serves as an example of a loadable PerlIO layer. Other future
608 possibilities include PerlIO::Array and PerlIO::Code.
609 See L<PerlIO::Scalar>.
613 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
614 functionality provided by a class (typically implemented in perl
615 code), from Nick Ing-Simmons.
617 use MIME::QuotedPrint;
618 open($fh,">Via(MIME::QuotedPrint)",$path)
620 This will automatically convert everything output to C<$fh>
621 to Quoted-Printable. See L<PerlIO::Via>.
625 C<Pod::ParseLink>, by Russ Allbery, has been added,
626 to parse L<> links in pods as described in the new
631 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
632 It converts POD data to formatted overstrike text.
633 See L<Pod::Text::Overstrike>.
637 C<Scalar::Util> is a selection of general-utility scalar subroutines,
638 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
642 C<sort> is a new pragma for controlling the behaviour of sort().
646 C<Storable> gives persistence to Perl data structures by allowing the
647 storage and retrieval of Perl data to and from files in a fast and
648 compact binary format, from Raphael Manfredi. See L<Storable>.
652 C<Switch>, from Damian Conway, has been added. Just by saying
656 you have C<switch> and C<case> available in Perl.
662 case 1 { print "number 1" }
663 case "a" { print "string a" }
664 case [1..10,42] { print "number in list" }
665 case (@array) { print "number in list" }
666 case /\w+/ { print "pattern" }
667 case qr/\w+/ { print "pattern" }
668 case (%hash) { print "entry in hash" }
669 case (\%hash) { print "entry in hash" }
670 case (\&sub) { print "arg to subroutine" }
671 else { print "previous case not true" }
678 C<Test::More> is yet another framework for writing test scripts,
679 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
683 C<Test::Simple> has the- basic utilities for writing tests, by Michael
684 Schwern. See L<Test::Simple>.
688 C<Text::Balanced> has been added, for extracting delimited text
689 sequences from strings, from Damian Conway.
691 use Text::Balanced 'extract_delimited';
693 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
695 $a will be "'never say never'", $b will be ', he never said'.
697 In addition to extract_delimited() there are also extract_bracketed(),
698 extract_quotelike(), extract_codeblock(), extract_variable(),
699 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
700 gen_extract_tagged(). With these you can implement rather advanced
701 parsing algorithms. See L<Text::Balanced>.
705 C<threads> is an interface interpreter threads, by Arthur Bergman.
706 Interpreter threads (ithreads) is the new thread model introduced in
707 Perl 5.6 but then available only as an internal interface for
708 extension writers. See L<threads>.
712 C<threads::shared> allows data sharing for interpreter threads, from
713 Arthur Bergman. In the ithreads model any data sharing between
714 threads must be explicit, as opposed to the old 5.005 thread model
715 where data sharing was implicit. See L<threads::shared>.
719 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
720 references (unlike the standard Tie::RefHash) The module is contained
721 within Tie::RefHash, see L<Tie::RefHash>.
725 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
726 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
730 C<Unicode::UCD> offers a querying interface to the Unicode Character
731 Database. See L<Unicode::UCD>.
735 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
736 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
740 C<Unicode::Normalize> implements the various Unicode normalization
741 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
745 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
746 typemaps. Nothing gets installed but for extension writers the code
751 =head2 Updated And Improved Modules and Pragmata
757 The following independently supported modules have been updated to the
758 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
759 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
760 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
761 Term::ANSIColor, Test, Text-Tabs+Wrap.
765 The attributes::reftype() now works on tied arguments.
769 AutoLoader can now be disabled with C<no AutoLoader;>,
773 B::Deparse has been significantly enhanced. It now can deparse almost
774 all of the standard test suite (so that the tests still succeed).
775 There is a make target "test.deparse" for trying this out.
779 Class::Struct can now define the classes in compile time.
783 Class::Struct now assigns the array/hash element if the accessor
784 is called with an array/hash element as the B<sole> argument.
788 Data::Dumper has now an option to sort hashes.
792 Data::Dumper has now an option to dump code references
797 The English module can now be used without the infamous performance
800 use English '-no_performance_hit';
802 (Assuming, of course, that one doesn't need the troublesome variables
803 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
804 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
808 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
809 new-style constant dispatch section (see L<ExtUtils::Constant>).
810 This means that they will be more robust and hopefully faster.
814 File::Find now has pre- and post-processing callbacks. It also
815 correctly changes directories when chasing symbolic links. Callbacks
816 (naughtily) exiting with "next;" instead of "return;" now work.
820 File::Find is now (again) reentrant. It also has been made
825 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
826 prototype mismatch with CORE::glob().
830 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
831 the returned list of filenames.
835 Devel::Peek now has an interface for the Perl memory statistics
836 (this works only if you are using perl's malloc, and if you have
837 compiled with debugging).
841 IPC::Open3 now allows the use of numeric file descriptors.
845 IO::Socket has now atmark() method, which returns true if the socket
846 is positioned at the out-of-band mark. The method is also exportable
847 as a sockatmark() function.
851 IO::Socket::INET has support for ReusePort option (if your platform
852 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
853 you may want to prefer ReuseAddr.
857 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
858 that the operating system will make one up.)
862 use lib now works identically to @INC. Removing directories
863 with 'no lib' now works.
867 Math::BigFloat and Math::BigInt have undergone a full rewrite.
868 They are now magnitudes faster, and they support various
869 bignum libraries such as GMP and PARI as their backends.
873 Net::Ping has been enhanced. There is now "external" protocol which
874 uses Net::Ping::External module which runs external ping(1) and parses
875 the output. An alpha version of Net::Ping::External is available in
876 CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
880 POSIX::sigaction() is now much more flexible and robust.
881 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
882 handlers, installing new handlers was not atomic.
886 C<%INC> now localised in a Safe compartment so that use/require work.
890 The Shell module now has an OO interface.
894 The Test module has been significantly enhanced.
898 The C<vars> pragma now supports declaring fully qualified variables.
899 (Something that C<our()> does not and will not support.)
903 The utf8:: name space (as in the pragma) provides various
904 Perl-callable functions to provide low level access to Perl's
905 internal Unicode representation. At the moment only length()
906 has been implemented.
910 =head1 Utility Changes
916 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
921 F<emacs/e2ctags.pl> is now much faster.
925 C<h2ph> now supports C trigraphs.
929 C<h2xs> now produces a template README.
933 C<h2xs> now uses C<Devel::PPort> for better portability between
934 different versions of Perl.
938 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
939 newly created extensions that define constants. Since the new code is
940 more correct (if you have two constants where the first one is a
941 prefix of the second one, the first constant B<never> gets defined),
942 less lossy (it uses integers for integer constant, as opposed to the
943 old code that used floating point numbers even for integer constants),
944 and slightly faster, you might want to consider regenerating your
945 extension code (the new scheme makes regenerating easy).
946 L<h2xs> now also supports C trigraphs.
950 C<libnetcfg> has been added to configure the libnet.
954 C<perlbug> is now much more robust. It also sends the bug report to
955 perl.org, not perl.com.
959 C<perlcc> has been rewritten and its user interface (that is,
960 command line) is much more like that of the UNIX C compiler, cc.
964 C<perlivp> is a new utility for doing Installation Verification
965 Procedure after installing Perl.
969 C<pod2html> now allows specifying a cache directory.
973 C<s2p> has been completely rewritten in Perl. (It is in fact a full
974 implementation of sed in Perl: you can use the sed functionality by
975 using the C<psed> utility.)
979 C<xsubpp> now understands POD documentation embedded in the *.xs files.
983 C<xsubpp> now supports OUT keyword.
987 =head1 New Documentation
993 perl56delta details the changes between the 5.005 release and the
998 perlclib documents the internal replacements for standard C library
999 functions. (Interesting only for extension writers and Perl core
1004 perldebtut is a Perl debugging tutorial.
1008 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1009 Note that unfortunately EBCDIC platforms that used to supported back in
1010 Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
1011 bring them back to the fold.
1015 perlintro is a gentle introduction to Perl.
1019 perliol documents the internals of PerlIO with layers.
1023 perlmodstyle is a style guide for writing modules.
1027 perlnewmod tells about writing and submitting a new module.
1031 perlpod has been rewritten to be clearer and to record the best
1032 practices gathered over the years.
1036 perlpodstyle is a more formal specification of the pod format,
1037 mainly of interest for writers of pod applications, not to
1038 people writing in pod.
1042 perlposix-bc explains using Perl on the POSIX-BC platform
1043 (an EBCDIC mainframe platform).
1047 perlretut is a regular expression tutorial.
1051 perlrequick is a regular expressions quick-start guide.
1052 Yes, much quicker than perlretut.
1056 perltodo has been updated.
1060 perltootc has been renamed as perltooc (to not to conflict
1061 with perltoot in filesystems restricted to "8.3" names)
1065 perluniintro is an introduction to using Unicode in Perl
1066 (perlunicode is more of a reference)
1070 perlutil explains the command line utilities packaged with the Perl
1075 The following platform-specific documents are available before
1076 the installation as README.I<platform>, and after the installation
1079 perlaix perlamiga perlapollo perlbeos perlbs2000
1080 perlce perlcygwin perldgux perldos perlepoc perlhpux
1081 perlhurd perlmachten perlmacos perlmint perlmpeix
1082 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1083 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1089 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1090 confusion with the Perl POSIX module.
1094 The documentation for the WinCE platform is called "CE", to avoid
1095 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1099 =head1 Performance Enhancements
1105 map() that changes the size of the list should now work faster.
1109 sort() has been changed to use primarily mergesort internally as
1110 opposed to the earlier quicksort. For very small lists this may
1111 result in slightly slower sorting times, but in general the speedup
1112 should be at least 20%. Additional bonuses are that the worst case
1113 behaviour of sort() is now better (in computer science terms it now
1114 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1115 worst-case run time behaviour), and that sort() is now stable
1116 (meaning that elements with identical keys will stay ordered as they
1117 were before the sort). See the C<sort> pragma for information.
1121 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1122 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1123 reasonably fast while producing a much better spread of values than
1124 the old hashing algorithm (originally by Chris Torek, later tweaked by
1125 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1126 all 3-char printable ASCII keys comes much closer to passing the
1127 DIEHARD random number generation tests. According to perlbench, this
1128 change has not affected the overall speed of Perl.
1132 unshift() should now be noticeably faster.
1136 =head1 Installation and Configuration Improvements
1138 =head2 Generic Improvements
1144 INSTALL now explains how you can configure Perl to use 64-bit
1145 integers even on non-64-bit platforms.
1149 Policy.sh policy change: if you are reusing a Policy.sh file
1150 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1151 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1152 them will now be changed to the new prefix, /foo/bar. (Previously
1153 only $prefix changed.) If you do not like this new behaviour,
1154 specify prefix, siteprefix, and vendorprefix explicitly.
1158 A new optional location for Perl libraries, otherlibdirs, is available.
1159 It can be used for example for vendor add-ons without disturbing Perl's
1160 own library directories.
1164 In many platforms the vendor-supplied 'cc' is too stripped-down to
1165 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1166 to be the case and 'cc' does not seem to be the GNU C compiler
1167 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1171 gcc needs to closely track the operating system release to avoid
1172 build problems. If Configure finds that gcc was built for a different
1173 operating system release than is running, it now gives a clearly visible
1174 warning that there may be trouble ahead.
1178 If binary compatibility with the 5.005 release is not wanted, Configure
1179 no longer suggests including the 5.005 modules in @INC.
1183 Configure C<-S> can now run non-interactively.
1187 configure.gnu now works with options with whitespace in them.
1191 installperl now outputs everything to STDERR.
1195 $Config{byteorder} is now computed dynamically (this is more robust
1196 with "fat binaries" where an executable image contains binaries for
1197 more than one binary platform.)
1201 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1202 get appended to the $Config{archname} (also known as $^O) anymore.
1203 Instead, if you explicitly choose not to use perlio (Configure command
1204 line option -Uuseperlio), you will get "-stdio" appended.
1208 Another change related to the architecture name is that "-64all"
1209 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1210 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1214 In AFS installations one can configure the root of the AFS to be
1215 somewhere else than the default F</afs> by using the Configure
1216 parameter C<-Dafsroot=/some/where/else>.
1220 APPLLIB_EXP, a less-know configuration-time definition, has been
1221 documented. It can be used to prepend site-specific directories
1222 to Perl's default search path (@INC), see INSTALL for information.
1226 The version of Berkeley DB used when the Perl (and, presumably, the
1227 DB_File extension) was built is now available as
1228 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1229 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1230 DB_VERSION_PATCH_CFG> from C.
1234 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1235 has been documented in INSTALL.
1239 If you have CPAN access (either network or a local copy such as a
1240 CD-ROM) you can during specify extra modules to Configure to build and
1241 install with Perl using the -Dextras=... option. See INSTALL for
1246 In addition to config.over a new override file, config.arch, is
1247 available. That is supposed to be used by hints file writers for
1248 architecture-wide changes (as opposed to config.over which is for
1253 If your file system supports symbolic links you can build Perl outside
1254 of the source directory by
1256 mkdir /tmp/perl/build/directory
1257 cd /tmp/perl/build/directory
1258 sh /path/to/perl/source/Configure -Dmksymlinks ...
1260 This will create in /tmp/perl/build/directory a tree of symbolic links
1261 pointing to files in /path/to/perl/source. The original files are left
1262 unaffected. After Configure has finished you can just say
1266 and Perl will be built and tested, all in /tmp/perl/build/directory.
1270 For Perl developers several new make targets for profiling
1271 and debugging have been added, see L<perlhack>.
1277 Use of the F<gprof> tool to profile Perl has been documented in
1278 L<perlhack>. There is a make target called "perl.gprof" for
1279 generating a gprofiled Perl executable.
1283 If you have GCC 3, there is a make target called "perl.gcov" for
1284 creating a gcoved Perl executable for coverage analysis. See
1289 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1290 have been added, see L<perlhack> for more information about pixie and
1297 Guidelines of how to construct minimal Perl installations have
1298 been added to INSTALL.
1302 The Thread extension is now not built at all under ithreads
1303 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1304 Thread extension requires being Configured with C<-Duse5005threads>).
1306 But note that the Thread.pm interface is now shared by both
1311 =head2 New Or Improved Platforms
1313 For the list of platforms known to support Perl,
1314 see L<perlport/"Supported Platforms">.
1320 AIX dynamic loading should be now better supported.
1324 AIX should now work better with gcc, threads, and 64-bitness. Also the
1325 long doubles support in AIX should be better now. See L<perlaix>.
1329 After a long pause, AmigaOS has been verified to be happy with Perl.
1333 AtheOS (http://www.atheos.cx/) is a new platform.
1337 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1341 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1345 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1346 have been regained. Many test suite tests still fail and the
1347 co-existence of Unicode and EBCDIC isn't quite settled, but the
1348 situation is much better than with Perl 5.6. See L<perlos390>,
1349 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1353 Building perl with -Duseithreads or -Duse5005threads now works under
1354 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1355 need a thread library package installed. See README.hpux.
1359 MacOS Classic (MacPerl has of course been available since
1360 perl 5.004 but now the source code bases of standard Perl
1361 and MacPerl have been synchronised)
1365 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1366 filesystems. (The case-insensitivity confused the Perl build process.)
1370 NCR MP-RAS is now supported.
1374 NetWare from Novell is now supported. See L<perlnetware>.
1378 NonStop-UX is now supported.
1382 Amdahl UTS UNIX mainframe platform is now supported.
1386 WinCE is now supported. See L<perlce>.
1390 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1391 support for dynamic loading. This is not selected by default,
1392 however, you must specify -Dusedl in the arguments of Configure.
1396 =head1 Selected Bug Fixes
1398 Numerous memory leaks and uninitialized memory accesses have been
1399 hunted down. Most importantly anonymous subs used to leak quite
1406 The autouse pragma didn't work for Multi::Part::Function::Names.
1410 chop(@list) in list context returned the characters chopped in
1411 reverse order. This has been reversed to be in the right order.
1415 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1416 when building the Perl binary. The only exception to this is SunOS 4.x,
1421 The behaviour of non-decimal but numeric string constants such as
1422 "0x23" was platform-dependent: in some platforms that was seen as 35,
1423 in some as 0, in some as a floating point number (don't ask). This
1424 was caused by Perl using the operating system libraries in a situation
1425 where the result of the string to number conversion is undefined: now
1426 Perl consistently handles such strings as zero in numeric contexts.
1430 The order of DESTROYs has been made more predictable.
1434 Several debugger fixes: exit code now reflects the script exit code,
1435 condition C<"0"> now treated correctly, the C<d> command now checks
1436 line number, the C<$.> no longer gets corrupted, all debugger output now
1437 goes correctly to the socket if RemotePort is set.
1441 L<dprofpp> -R didn't work.
1445 C<*foo{FORMAT}> now works.
1449 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1450 the Tk extension with 5.6.0.)
1454 Lexicals I: lexicals outside an eval "" weren't resolved
1455 correctly inside a subroutine definition inside the eval "" if they
1456 were not already referenced in the top level of the eval""ed code.
1460 Lexicals II: lexicals leaked at file scope into subroutines that
1461 were declared before the lexicals.
1465 Lexical warnings now propagating correctly between scopes.
1469 Line renumbering with eval and C<#line> now works.
1473 Fixed numerous memory leaks, especially in eval "".
1477 mkdir() now ignores trailing slashes in the directory name,
1478 as mandated by POSIX.
1482 Some versions of glibc have a broken modfl(). This affects builds
1483 with C<-Duselongdouble>. This version of Perl detects this brokenness
1484 and has a workaround for it. The glibc release 2.2.2 is known to have
1485 fixed the modfl() bug.
1489 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1490 return 27406, instead of 27047).
1494 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1495 more compatible with 5.005. Infinity is now recognised as a number.
1499 Attributes (like :shared) didn't work with our().
1503 our() variables will not cause "will not stay shared" warnings.
1507 pack "Z" now correctly terminates the string with "\0".
1511 Fix password routines which in some shadow password platforms
1512 (e.g. HP-UX) caused getpwent() to return every other entry.
1516 The PERL5OPT environment variable (for passing command line arguments
1517 to Perl) didn't work for more than a single group of options.
1521 PERL5OPT with embedded spaces didn't work.
1525 printf() no longer resets the numeric locale to "C".
1529 C<q(a\\b)> now parses correctly as C<'a\\b'>.
1533 Printing quads (64-bit integers) with printf/sprintf now works
1534 without the q L ll prefixes (assuming you are on a quad-capable platform).
1538 Regular expressions on references and overloaded scalars now work.
1542 Right-hand side magic (GMAGIC) could in many cases such as string
1543 concatenation be invoked too many times.
1547 scalar() now forces scalar context even when used in void context.
1551 SOCKS support is now much more robust.
1555 sort() arguments are now compiled in the right wantarray context
1556 (they were accidentally using the context of the sort() itself).
1560 Changed the POSIX character class C<[[:space:]]> to include the (very
1561 rare) vertical tab character. Added a new POSIX-ish character class
1562 C<[[:blank:]]> which stands for horizontal whitespace (currently,
1563 the space and the tab).
1567 The tainting behaviour of sprintf() has been rationalized. It does
1568 not taint the result of floating point formats anymore, making the
1569 behaviour consistent with that of string interpolation.
1573 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
1577 All but the first argument of the IO syswrite() method are now optional.
1581 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1582 in multiple threads simultaneously are now thread-safe.
1586 Tie::ARRAY SPLICE method was broken.
1590 Allow read-only string on left hand side of non-modifying tr///.
1594 Several Unicode fixes.
1600 BOMs (byte order marks) in the beginning of Perl files
1601 (scripts, modules) should now be transparently skipped.
1602 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1606 The character tables have been updated to Unicode 3.1.1.
1610 Comparing with utf8 data does not magically upgrade non-utf8 data
1615 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1619 Concatenation with the C<.> operator or via variable interpolation,
1620 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1621 substitution with C<s///>, single-quoted UTF8, should now work.
1625 The C<tr///> operator now works. Note that the C<tr///CU>
1626 functionality has been removed (but see pack('U0', ...)).
1630 C<eval "v200"> now works.
1634 Zero entries were missing from the Unicode classes like C<IsDigit>.
1640 =head2 Platform Specific Changes and Fixes
1648 Perl now works on post-4.0 BSD/OSes.
1654 Setting C<$0> now works (as much as possible; see perlvar for details).
1660 Numerous updates; currently synchronised with Cygwin 1.1.4.
1664 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1670 EPOC update after Perl 5.6.0. See README.epoc.
1676 Perl now works on post-3.0 FreeBSDs.
1682 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1688 Numerous compilation flag and hint enhancements; accidental mixing
1689 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1699 Long doubles should now work (see INSTALL).
1703 Linux previously had problems related to sockaddrlen when using
1704 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1712 Compilation of the standard Perl distribution in MacOS Classic should
1713 now work if you have the Metrowerks development environment and
1714 the missing Mac-specific toolkit bits. Contact the macperl mailing
1721 MPE/iX update after Perl 5.6.0. See README.mpeix.
1727 Perl now works on NetBSD/sparc.
1733 Now works with usethreads (see INSTALL).
1739 64-bitness using the Sun Workshop compiler now works.
1743 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1745 The operating system version letter now recorded in $Config{osvers}.
1746 Allow compiling with gcc (previously explicitly forbidden). Compiling
1747 with gcc still not recommended because buggy code results, even with
1754 Fixed various alignment problems that lead into core dumps either
1755 during build or later; no longer dies on math errors at runtime;
1756 now using full quad integers (64 bits), previously was using
1757 only 46 bit integers for speed.
1763 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
1764 (see INSTALL); now works with Perl's malloc.
1774 accept() no longer leaks memory.
1778 Borland C++ v5.5 is now a supported compiler that can build Perl.
1779 However, the generated binaries continue to be incompatible with those
1780 generated by the other supported compilers (GCC and Visual C++).
1784 Better chdir() return value for a non-existent directory.
1788 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
1792 New %ENV entries now propagate to subprocesses.
1796 $ENV{LIB} now used to search for libs under Visual C.
1800 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
1801 Other bugs in chdir() and Cwd::cwd() have also been fixed.
1805 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
1809 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
1813 The makefiles now provide a single switch to bulk-enable all the features
1814 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
1818 Allow REG_EXPAND_SZ keys in the registry.
1822 Can now send() from all threads, not just the first one.
1826 Fake signal handling reenabled, bugs and all.
1830 Less stack reserved per thread so that more threads can run
1831 concurrently. (Still 16M per thread.)
1835 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
1836 (works better when perl is running as service).
1840 Better UNC path handling under ithreads.
1844 wait() and waitpid() now work much better.
1848 winsock handle leak fixed.
1854 =head1 New or Changed Diagnostics
1860 All regular expression compilation error messages are now hopefully
1861 easier to understand both because the error message now comes before
1862 the failed regex and because the point of failure is now clearly
1863 marked by a C<E<lt>-- HERE> marker.
1867 The various "opened only for", "on closed", "never opened" warnings
1868 drop the C<main::> prefix for filehandles in the C<main> package,
1869 for example C<STDIN> instead of <main::STDIN>.
1873 The "Unrecognized escape" warning has been extended to include C<\8>,
1874 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
1878 Two new debugging options have been added: if you have compiled your
1879 Perl with debugging, you can use the -DT and -DR options to trace
1880 tokenising and to add reference counts to displaying variables,
1885 If an attempt to use a (non-blessed) reference as an array index
1886 is made, a warning is given.
1890 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
1891 now give a warning. This may be a problem for generated and evaled
1896 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
1897 using the C<"C"> format you will get an optional warning. Similarly
1898 for the C<"c"> format and a number less than -128 or more than 127.
1902 Certain regex modifiers such as C<(?o)> make sense only if applied to
1903 the entire regex. You will an optional warning if you try to do otherwise.
1907 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
1908 deprecated for a while. Now you will get an optional warning.
1912 =head1 Changed Internals
1918 perlapi.pod (a companion to perlguts) now attempts to document the
1923 You can now build a really minimal perl called microperl.
1924 Building microperl does not require even running Configure;
1925 C<make -f Makefile.micro> should be enough. Beware: microperl makes
1926 many assumptions, some of which may be too bold; the resulting
1927 executable may crash or otherwise misbehave in wondrous ways.
1928 For careful hackers only.
1932 Added rsignal(), whichsig(), do_join() to the publicised API.
1936 Made possible to propagate customised exceptions via croak()ing.
1940 Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
1944 Now xsubs can have attributes just like subs.
1948 Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
1949 For the full list of the available APIs see L<perlapi>.
1953 dTHR and djSP have been obsoleted; the former removed (because it's
1954 a no-op) and the latter replaced with dSP.
1958 PERL_OBJECT has been completely removed.
1962 The MAGIC constants (e.g. C<'P'>) have been macrofied
1963 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
1964 and maintainability.
1968 The regex compiler now maintains a structure that identifies nodes in
1969 the compiled bytecode with the corresponding syntactic features of the
1970 original regex expression. The information is attached to the new
1971 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
1972 complete information.
1976 The C code has been made much more C<gcc -Wall> clean. Some warning
1977 messages still remain in some platforms, so if you are compiling with
1978 gcc you may see some warnings about dubious practices. The warnings
1979 are being worked on.
1983 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
1987 Documentation on how to use the Perl source repository has been added
1988 to F<Porting/repository.pod>.
1992 There are now several profiling make targets
1996 The C<op_clear> and C<op_null> are now exported.
2000 =head1 Security Vulnerability Closed
2002 (This change was already made in 5.7.0 but bears repeating here.)
2004 A potential security vulnerability in the optional suidperl component
2005 of Perl was identified in August 2000. suidperl is neither built nor
2006 installed by default. As of November 2001 the only known vulnerable
2007 platform is Linux, most likely all Linux distributions. CERT and
2008 various vendors and distributors have been alerted about the vulnerability.
2009 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2010 for more information.
2012 The problem was caused by Perl trying to report a suspected security
2013 exploit attempt using an external program, /bin/mail. On Linux
2014 platforms the /bin/mail program had an undocumented feature which
2015 when combined with suidperl gave access to a root shell, resulting in
2016 a serious compromise instead of reporting the exploit attempt. If you
2017 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2018 suidperl is not installed, you are safe.
2020 The exploit attempt reporting feature has been completely removed from
2021 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2022 from all the Perl 5.7 releases), so that particular vulnerability
2023 isn't there anymore. However, further security vulnerabilities are,
2024 unfortunately, always possible. The suidperl functionality is most
2025 probably going to be removed in Perl 5.10. In any case, suidperl
2026 should only be used by security experts who know exactly what they are
2027 doing and why they are using suidperl instead of some other solution
2028 such as sudo (see http://www.courtesan.com/sudo/).
2032 Several new tests have been added, especially for the F<lib> subsection.
2034 The tests are now reported in a different order than in earlier Perls.
2035 (This happens because the test scripts from under t/lib have been moved
2036 to be closer to the library/extension they are testing.)
2038 =head1 Known Problems
2040 Note that unlike other sections in this document (which describe
2041 changes since 5.7.0) this section is cumulative containing known
2042 problems for all the 5.7 releases.
2050 In AIX 4.2 Perl extensions that use C++ functions that use statics
2051 may have problems in that the statics are not getting initialized.
2052 In newer AIX releases this has been solved by linking Perl with
2053 the libC_r library, but unfortunately in AIX 4.2 the said library
2054 has an obscure bug where the various functions related to time
2055 (such as time() and gettimeofday()) return broken values, and
2056 therefore in AIX 4.2 Perl is not linked against the libC_r.
2060 vac 5.0.0.0 May Produce Buggy Code For Perl
2062 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2063 resulting in few random tests failing, but when the failing tests
2064 are run by hand, they succeed. We suggest upgrading to at least
2065 vac version 5.0.1.0, that has been known to compile Perl correctly.
2066 "lslpp -L|grep vac.C" will tell you the vac version.
2070 =head2 Amiga Perl Invoking Mystery
2072 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2073 works, but for example C<bin:perl -v> doesn't. The exact reason is
2074 known but the current suspect is the F<ixemul> library.
2076 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2078 Don't panic. Read INSTALL 'make test' section instead.
2080 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2082 The subtests 11 and 12 sometimes fail and sometimes work.
2084 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2086 The lib/io_multihomed test may hang in HP-UX if Perl has been
2087 configured to be 64-bit. Because other 64-bit platforms do not hang in
2088 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2089 test attempts to create and connect to "multihomed" sockets (sockets
2090 which have multiple IP addresses).
2092 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2094 If perl is configured with -Duse64bitall, the successful result of the
2095 subtest 10 of lib/posix may arrive before the successful result of the
2096 subtest 9, which confuses the test harness so much that it thinks the
2099 =head2 Linux With Sfio Fails op/misc Test 48
2105 OS/390 has rather many test failures but the situation is actually
2106 better than it was in 5.6.0, it's just that so many new modules and
2107 tests have been added.
2109 Failed Test Stat Wstat Total Fail Failed List of Failed
2110 -----------------------------------------------------------------------------
2111 ../ext/B/Deparse.t 14 1 7.14% 14
2112 ../ext/B/Showlex.t 1 1 100.00% 1
2113 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2115 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2116 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2117 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2118 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2119 ../lib/warnings.t 434 1 0.23% 75
2120 ../lib/ExtUtils.t 27 1 3.70% 25
2121 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2122 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2123 ../lib/User/pwent.t 9 1 11.11% 4
2124 op/pat.t 660 6 0.91% 242-243 424-425
2126 op/split.t 0 9 ?? ?? % ??
2127 op/taint.t 174 3 1.72% 156 162 168
2128 op/tr.t 70 3 4.29% 50 58-59
2129 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2131 =head2 op/sprintf tests 129 and 130
2133 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2134 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2135 The failing platforms do not comply with the ANSI C Standard, line
2136 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2137 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2138 the printf format "%.0f", most often they produce "0" and "-0".)
2140 =head2 Failure of Thread tests
2142 B<Note that support for 5.005-style threading remains experimental.>
2144 The following tests are known to fail due to fundamental problems in
2145 the 5.005 threading implementation. These are not new failures--Perl
2146 5.005_0x has the same bugs, but didn't have these tests.
2149 t/lib/thr5005.t 19-20
2157 ext/POSIX/sigaction subtests 6 and 13 may fail.
2161 lib/ExtUtils may spuriously claim that subtest 28 failed,
2162 which is interesting since the test only has 27 tests.
2166 Numerous numerical test failures
2168 op/numconvert 209,210,217,218
2170 ext/Time/HiRes/HiRes 9
2171 lib/Math/BigInt/t/bigintpm 1145
2174 These tests fail because of yet unresolved floating point inaccuracies.
2180 There are a few known test failures, see L<perluts>.
2184 Rather many tests are failing in VMS but that actually more tests
2185 succeed in VMS than they used to, it's just that there are many,
2186 many more tests than there used to be.
2188 Here are the known failures from some compiler/platform combinations.
2190 DEC C V5.3-006 on OpenVMS VAX V6.2
2192 [-.ext.list.util.t]tainted..............FAILED on test 3
2193 [-.ext.posix]sigaction..................FAILED on test 7
2194 [-.ext.time.hires]hires.................FAILED on test 14
2195 [-.lib.file.find]taint..................FAILED on test 17
2196 [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
2197 [-.lib.test.simple.t]exit...............FAILED on test 1
2198 [.lib]vmsish............................FAILED on test 13
2199 [.op]sprintf............................FAILED on test 12
2200 Failed 8/399 tests, 91.23% okay.
2202 DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and
2203 Compaq C V6.2-008 on OpenVMS Alpha V7.1
2205 [-.ext.list.util.t]tainted..............FAILED on test 3
2206 [-.lib.file.find]taint..................FAILED on test 17
2207 [-.lib.test.simple.t]exit...............FAILED on test 1
2208 [.lib]vmsish............................FAILED on test 13
2209 Failed 4/399 tests, 92.48% okay.
2211 Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
2213 [-.ext.b]showlex........................FAILED on test 1
2214 [-.ext.list.util.t]tainted..............FAILED on test 3
2215 [-.lib.file.find]taint..................FAILED on test 17
2216 [-.lib.test.simple.t]exit...............FAILED on test 1
2217 [.lib]vmsish............................FAILED on test 13
2218 [.op]misc...............................FAILED on test 49
2219 Failed 6/401 tests, 92.77% okay.
2223 In multi-CPU boxes there are some problems with the I/O buffering:
2224 some output may appear twice.
2226 =head2 Localising a Tied Variable Leaks Memory
2229 tie my %tie_hash => 'Tie::StdHash';
2233 local($tie_hash{Foo}) = 1; # leaks
2235 Code like the above is known to leak memory every time the local()
2238 =head2 Self-tying of Arrays and Hashes Is Forbidden
2240 Self-tying of arrays and hashes is broken in rather deep and
2241 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2242 frustrated at the mysterious results (core dumps, most often) it is
2243 for now forbidden (you will get a fatal error even from an attempt).
2245 =head2 Variable Attributes are not Currently Usable for Tieing
2247 This limitation will hopefully be fixed in future. (Subroutine
2248 attributes work fine for tieing, see L<Attribute::Handlers>).
2250 =head2 Building Extensions Can Fail Because Of Largefiles
2252 Some extensions like mod_perl are known to have issues with
2253 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2254 default to 64 bits wide, where supported. Modules may fail to compile
2255 at all or compile and work incorrectly. Currently there is no good
2256 solution for the problem, but Configure now provides appropriate
2257 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2258 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2259 having problems can try configuring themselves without the
2260 largefileness. This is admittedly not a clean solution, and the
2261 solution may not even work at all. One potential failure is whether
2262 one can (or, if one can, whether it's a good idea) link together at
2263 all binaries with different ideas about file offsets, all this is
2266 =head2 The Compiler Suite Is Still Experimental
2268 The compiler suite is slowly getting better but is nowhere near
2271 =head2 The Long Double Support is Still Experimental
2273 The ability to configure Perl's numbers to use "long doubles",
2274 floating point numbers of hopefully better accuracy, is still
2275 experimental. The implementations of long doubles are not yet
2276 widespread and the existing implementations are not quite mature
2277 or standardised, therefore trying to support them is a rare
2278 and moving target. The gain of more precision may also be offset
2279 by slowdown in computations (more bits to move around, and the
2280 operations are more likely to be executed by less optimised
2283 =head1 Reporting Bugs
2285 If you find what you think is a bug, you might check the articles
2286 recently posted to the comp.lang.perl.misc newsgroup and the perl
2287 bug database at http://bugs.perl.org. There may also be
2288 information at http://www.perl.com/perl/, the Perl Home Page.
2290 If you believe you have an unreported bug, please run the B<perlbug>
2291 program included with your release. Be sure to trim your bug down
2292 to a tiny but sufficient test case. Your bug report, along with the
2293 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2294 analysed by the Perl porting team.
2298 The F<Changes> file for exhaustive details on what changed.
2300 The F<INSTALL> file for how to build Perl.
2302 The F<README> file for general stuff.
2304 The F<Artistic> and F<Copying> files for copyright information.
2308 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.