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, $2, ...) are now
141 more consistently unset if the match fails, instead of leaving false
142 data lying around in them.
146 The tr///C and tr///U features have been removed and will not return;
147 the interface was a mistake. Sorry about that. For similar
148 functionality, see pack('U0', ...) and pack('C0', ...).
152 Although "you shouldn't do that", it was possible to write code that
153 depends on Perl's hashed key order (Data::Dumper does this). The new
154 algorithm "One-at-a-Time" produces a different hashed key order.
155 More details are in L</"Performance Enhancements">.
159 The list of filenames from glob() (or <...>) is now by default sorted
160 alphabetically to be csh-compliant. (bsd_glob() does still sort platform
161 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
165 =head1 Core Enhancements
167 =head2 AUTOLOAD Is Now Lvaluable
169 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
170 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
172 =head2 PerlIO is Now The Default
178 IO is now by default done via PerlIO rather than system's "stdio".
179 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
180 handle's behaviour. Layers can be specified at open time via 3-arg
183 open($fh,'>:crlf :utf8', $path) || ...
185 or on already opened handles via extended C<binmode>:
187 binmode($fh,':encoding(iso-8859-7)');
189 The built-in layers are: unix (low level read/write), stdio (as in
190 previous Perls), perlio (re-implementation of stdio buffering in a
191 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
192 but available on any platform). A mmap layer may be available if
193 platform supports it (mostly UNIXes).
195 Layers to be applied by default may be specified via the 'open' pragma.
197 See L</"Installation and Configuration Improvements"> for the effects
198 of PerlIO on your architecture name.
202 File handles can be marked as accepting Perl's internal encoding of Unicode
203 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
205 open($fh,">:utf8","Uni.txt");
207 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
208 for you since it's not UTF-8 what you will be getting but instead
209 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
210 http://www.unicode.org/unicode/reports/tr16/ for more information.
211 In future releases this naming may change.
215 File handles can translate character encodings from/to Perl's internal
216 Unicode form on read/write via the ":encoding()" layer.
220 File handles can be opened to "in memory" files held in Perl scalars via:
222 open($fh,'>', \$variable) || ...
226 Anonymous temporary files are available without need to
227 'use FileHandle' or other module via
229 open($fh,"+>", undef) || ...
231 That is a literal undef, not an undefined value.
235 The list form of C<open> is now implemented for pipes (at least on UNIX):
237 open($fh,"-|", 'cat', '/etc/motd')
239 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
244 The following builtin functions are now overridable: chop(), chomp(),
245 each(), keys(), pop(), push(), shift(), splice(), unshift().
249 Formats now support zero-padded decimal fields.
253 Perl now tries internally to use integer values in numeric conversions
254 and basic arithmetics (+ - * /) if the arguments are integers, and
255 tries also to keep the results stored internally as integers.
256 This change leads into often slightly faster and always less lossy
257 arithmetics. (Previously Perl always preferred floating point numbers
262 The printf() and sprintf() now support parameter reordering using the
263 C<%\d+\$> and C<*\d+\$> syntaxes. For example
265 print "%2\$s %1\$s\n", "foo", "bar";
267 will print "bar foo\n"; This feature helps in writing
268 internationalised software.
272 Unicode in general should be now much more usable. Unicode can be
273 used in hash keys, Unicode in regular expressions should work now,
274 Unicode in tr/// should work now (though tr/// seems to be a
275 particularly tricky to get right, so you have been warned)
279 The Unicode Character Database coming with Perl has been upgraded
280 to Unicode 3.1. For more information, see http://www.unicode.org/,
281 and http://www.unicode.org/unicode/reports/tr27/
283 For developers interested in enhancing Perl's Unicode capabilities:
284 almost all the UCD files are included with the Perl distribution in
285 the lib/unicode subdirectory. The most notable omission, for space
286 considerations, is the Unihan database.
290 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
291 added. "Blank" is like C isblank(), that is, it contains only
292 "horizontal whitespace" (the space character is, the newline isn't),
293 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
294 isn't, since that includes the vertical tabulator character, whereas
299 =head2 Signals Are Now Safe
301 Perl used to be fragile in that signals arriving at inopportune moments
302 could corrupt Perl's internal state.
304 =head2 Understanding of Numbers
306 In general a lot of fixing has happened in the area of Perl's
307 understanding of numbers, both integer and floating point. Since in
308 many systems the standard number parsing functions like C<strtoul()>
309 and C<atof()> seem to have bugs, Perl tries to work around their
310 deficiencies. This results hopefully in more accurate numbers.
316 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
317 in multiple arguments.)
321 END blocks are now run even if you exit/die in a BEGIN block.
322 Internally, the execution of END blocks is now controlled by
323 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
324 behaviour for Perl embedders. This will default in 5.10. See
329 Lexicals I: lexicals outside an eval "" weren't resolved
330 correctly inside a subroutine definition inside the eval "" if they
331 were not already referenced in the top level of the eval""ed code.
335 Lexicals II: lexicals leaked at file scope into subroutines that
336 were declared before the lexicals.
340 Lvalue subroutines can now return C<undef> in list context.
344 A new special regular expression variable has been introduced:
345 C<$^N>, which contains the most-recently closed group (submatch).
349 C<no Module;> now works even if there is no "sub unimport" in the Module.
353 The numerical comparison operators return C<undef> if either operand
354 is a NaN. Previously the behaviour was unspecified.
358 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
362 my __PACKAGE__ $obj now works.
366 prototype(\&) is now available.
370 Right-hand side magic (GMAGIC) could in many cases such as string
371 concatenation be invoked too many times.
375 The rules for allowing underscores (underbars) in numeric constants
376 have been relaxed and simplified: now you can have an underscore
377 simply B<between digits>.
381 An UNTIE method is now available.
385 L<utime> now supports C<utime undef, undef, @files> to change the
386 file timestamps to the current time.
390 C<eval "v200"> now works.
394 =head1 Modules and Pragmata
396 =head2 New Modules and Pragmata
402 C<Attribute::Handlers> allows a class to define attribute handlers.
405 use Attribute::Handlers;
406 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
408 # later, in some package using or inheriting from MyPack...
410 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
412 Both variables and routines can have attribute handlers. Handlers can
413 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
414 exact compilation phase (BEGIN, CHECK, INIT, or END).
418 B<B::Concise> is a new compiler backend for walking the Perl syntax
419 tree, printing concise info about ops, from Stephen McCamant. The
420 output is highly customisable. See L<B::Concise>.
424 C<Class::ISA> for reporting the search path for a class's ISA tree,
425 by Sean Burke, has been added. See L<Class::ISA>.
429 C<Cwd> has now a split personality: if possible, an XS extension is
430 used, (this will hopefully be faster, more secure, and more robust)
431 but if not possible, the familiar Perl implementation is used.
435 C<Devel::PPPort>, from Kenneth Albanowski, has been added. It is
436 primarily used by C<h2xs> to enhance portability of of XS modules
437 between different versions of Perl.
441 C<Digest>, frontend module for calculating digests (checksums), from
442 Gisle Aas, has been added. See L<Digest>.
446 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
447 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
449 use Digest::MD5 'md5_hex';
451 $digest = md5_hex("Thirsty Camel");
453 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
455 NOTE: the C<MD5> backward compatibility module is deliberately not
456 included since its use is discouraged.
460 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
461 between different character encodings. Support for Unicode,
462 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
463 compiled in to the module. Several other encodings (like Japanese,
464 Chinese, and MacIntosh encodings) are included and will be loaded at
465 runtime. See L<Encode>.
467 Any encoding supported by Encode module is also available to the
468 ":encoding()" layer if PerlIO is used.
472 C<I18N::Langinfo> can be use to query locale information.
473 See L<I18N::Langinfo>.
477 C<I18N::LangTags> has functions for dealing with RFC3066-style
478 language tags, by Sean Burke. See <I18N::LangTags>.
482 C<ExtUtils::Constant> is a new tool for extension writers for
483 generating XS code to import C header constants, by Nicholas Clark.
484 See L<ExtUtils::Constant>.
488 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
489 from Damian Conway. See L<Filter::Simple>.
495 use Filter::Simple sub {
496 while (my ($from, $to) = splice @_, 0, 2) {
505 use MyFilter qr/red/ => 'green';
507 print "red\n"; # this code is filtered, will print "green\n"
508 print "bored\n"; # this code is filtered, will print "bogreen\n"
512 print "red\n"; # this code is not filtered, will print "red\n"
516 C<File::Temp> allows one to create temporary files and directories in
517 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
521 C<Filter::Util::Call> provides you with the framework to write
522 I<Source Filters> in Perl, from Paul Marquess. For most uses the
523 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
527 L<libnet> is a collection of perl5 modules related to network
528 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
529 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
531 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
535 C<List::Util> is a selection of general-utility list subroutines, like
536 sum(), min(), first(), and shuffle(), by Graham barr. See L<List::Util>.
540 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
541 C<Locale::Language>, from Neil Bowers, have been added. They provide the
542 codes for various locale standards, such as "fr" for France, "usd" for
543 US Dollar, and "jp" for Japanese.
547 $country = code2country('jp'); # $country gets 'Japan'
548 $code = country2code('Norway'); # $code gets 'no'
550 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
551 and L<Locale::Language>.
555 C<Locale::Maketext> is localization framework from Sean Burke. See
556 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
557 article about software localization, originally published in The Perl
558 Journal #13, republished here with kind permission.
562 C<Memoize> can make your functions faster by trading space for time,
563 from Mark-Jason Dominus. See L<Memoize>.
567 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
568 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
573 $encoded = encode_base64('Aladdin:open sesame');
574 $decoded = decode_base64($encoded);
576 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
582 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
583 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
584 Extensions)>, from Gisle Aas.
586 use MIME::QuotedPrint;
588 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
589 $decoded = decode_qp($encoded);
591 print $encoded, "\n"; # "Smiley in Unicode: =263A"
593 MIME::QuotedPrint has been enhanced to provide the basic methods
594 necessary to use it with PerlIO::Via as in :
596 use MIME::QuotedPrint;
597 open($fh,">Via(MIME::QuotedPrint)",$path)
599 See L<MIME::QuotedPrint>.
603 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
608 C<open> is a new pragma for setting the default I/O disciplines
613 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
614 Perl scalars as discussed above, from Nick Ing-Simmons. It also
615 serves as an example of a loadable PerlIO layer. Other future
616 possibilities include PerlIO::Array and PerlIO::Code.
617 See L<PerlIO::Scalar>.
621 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
622 functionality provided by a class (typically implemented in perl
623 code), from Nick Ing-Simmons.
625 use MIME::QuotedPrint;
626 open($fh,">Via(MIME::QuotedPrint)",$path)
628 This will automatically convert everything output to C<$fh>
629 to Quoted-Printable. See L<PerlIO::Via>.
633 C<Pod::ParseLink>, by Russ Allbery, has been added,
634 to parse L<> links in pods as described in the new
639 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
640 It converts POD data to formatted overstrike text.
641 See L<Pod::Text::Overstrike>.
645 C<Scalar::Util> is a selection of general-utility scalar subroutines,
646 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
650 C<sort> is a new pragma for controlling the behaviour of sort().
654 C<Storable> gives persistence to Perl data structures by allowing the
655 storage and retrieval of Perl data to and from files in a fast and
656 compact binary format, from Raphael Manfredi. See L<Storable>.
660 C<Switch>, from Damian Conway, has been added. Just by saying
664 you have C<switch> and C<case> available in Perl.
670 case 1 { print "number 1" }
671 case "a" { print "string a" }
672 case [1..10,42] { print "number in list" }
673 case (@array) { print "number in list" }
674 case /\w+/ { print "pattern" }
675 case qr/\w+/ { print "pattern" }
676 case (%hash) { print "entry in hash" }
677 case (\%hash) { print "entry in hash" }
678 case (\&sub) { print "arg to subroutine" }
679 else { print "previous case not true" }
686 C<Test::More> is yet another framework for writing test scripts,
687 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
691 C<Test::Simple> has the- basic utilities for writing tests, by Michael
692 Schwern. See L<Test::Simple>.
696 C<Text::Balanced> has been added, for extracting delimited text
697 sequences from strings, from Damian Conway.
699 use Text::Balanced 'extract_delimited';
701 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
703 $a will be "'never say never'", $b will be ', he never said'.
705 In addition to extract_delimited() there are also extract_bracketed(),
706 extract_quotelike(), extract_codeblock(), extract_variable(),
707 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
708 gen_extract_tagged(). With these you can implement rather advanced
709 parsing algorithms. See L<Text::Balanced>.
713 C<threads> is an interface interpreter threads, by Arthur Bergman.
714 Interpreter threads (ithreads) is the new thread model introduced in
715 Perl 5.6 but then available only as an internal interface for
716 extension writers. See L<threads>.
720 C<threads::shared> allows data sharing for interpreter threads, from
721 Arthur Bergman. In the ithreads model any data sharing between
722 threads must be explicit, as opposed to the old 5.005 thread model
723 where data sharing was implicit. See L<threads::shared>.
727 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
728 references (unlike the standard Tie::RefHash) The module is contained
729 within Tie::RefHash, see L<Tie::RefHash>.
733 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
734 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
738 C<Unicode::UCD> offers a querying interface to the Unicode Character
739 Database. See L<Unicode::UCD>.
743 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
744 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
748 C<Unicode::Normalize> implements the various Unicode normalization
749 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
753 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
754 typemaps. Nothing gets installed but for extension writers the code
759 =head2 Updated And Improved Modules and Pragmata
765 The following independently supported modules have been updated to the
766 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
767 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
768 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
769 Term::ANSIColor, Test, Text-Tabs+Wrap.
773 The attributes::reftype() now works on tied arguments.
777 AutoLoader can now be disabled with C<no AutoLoader;>,
781 B::Deparse has been significantly enhanced. It now can deparse almost
782 all of the standard test suite (so that the tests still succeed).
783 There is a make target "test.deparse" for trying this out.
787 Class::Struct can now define the classes in compile time.
791 Class::Struct now assigns the array/hash element if the accessor
792 is called with an array/hash element as the B<sole> argument.
796 Data::Dumper has now an option to sort hashes.
800 Data::Dumper has now an option to dump code references
805 The English module can now be used without the infamous performance
808 use English '-no_performance_hit';
810 (Assuming, of course, that one doesn't need the troublesome variables
811 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
812 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
816 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
817 new-style constant dispatch section (see L<ExtUtils::Constant>).
818 This means that they will be more robust and hopefully faster.
822 File::Find now has pre- and post-processing callbacks. It also
823 correctly changes directories when chasing symbolic links. Callbacks
824 (naughtily) exiting with "next;" instead of "return;" now work.
828 File::Find is now (again) reentrant. It also has been made
833 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
834 prototype mismatch with CORE::glob().
838 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
839 the returned list of filenames.
843 Devel::Peek now has an interface for the Perl memory statistics
844 (this works only if you are using perl's malloc, and if you have
845 compiled with debugging).
849 IPC::Open3 now allows the use of numeric file descriptors.
853 IO::Socket has now atmark() method, which returns true if the socket
854 is positioned at the out-of-band mark. The method is also exportable
855 as a sockatmark() function.
859 IO::Socket::INET has support for ReusePort option (if your platform
860 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
861 you may want to prefer ReuseAddr.
865 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
866 that the operating system will make one up.)
870 use lib now works identically to @INC. Removing directories
871 with 'no lib' now works.
875 Math::BigFloat and Math::BigInt have undergone a full rewrite.
876 They are now magnitudes faster, and they support various
877 bignum libraries such as GMP and PARI as their backends.
881 Net::Ping has been enhanced. There is now "external" protocol which
882 uses Net::Ping::External module which runs external ping(1) and parses
883 the output. An alpha version of Net::Ping::External is available in
884 CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
888 POSIX::sigaction() is now much more flexible and robust.
889 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
890 handlers, installing new handlers was not atomic.
894 C<%INC> now localised in a Safe compartment so that use/require work.
898 The Shell module now has an OO interface.
902 The Test module has been significantly enhanced.
906 The C<vars> pragma now supports declaring fully qualified variables.
907 (Something that C<our()> does not and will not support.)
911 The utf8:: name space (as in the pragma) provides various
912 Perl-callable functions to provide low level access to Perl's
913 internal Unicode representation. At the moment only length()
914 has been implemented.
918 =head1 Utility Changes
924 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
929 F<emacs/e2ctags.pl> is now much faster.
933 C<h2ph> now supports C trigraphs.
937 C<h2xs> now produces a template README.
941 C<h2xs> now uses C<Devel::PPort> for better portability between
942 different versions of Perl.
946 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
947 newly created extensions that define constants. Since the new code is
948 more correct (if you have two constants where the first one is a
949 prefix of the second one, the first constant B<never> gets defined),
950 less lossy (it uses integers for integer constant, as opposed to the
951 old code that used floating point numbers even for integer constants),
952 and slightly faster, you might want to consider regenerating your
953 extension code (the new scheme makes regenerating easy).
954 L<h2xs> now also supports C trigraphs.
958 C<libnetcfg> has been added to configure the libnet.
962 C<perlbug> is now much more robust. It also sends the bug report to
963 perl.org, not perl.com.
967 C<perlcc> has been rewritten and its user interface (that is,
968 command line) is much more like that of the UNIX C compiler, cc.
972 C<perlivp> is a new utility for doing Installation Verification
973 Procedure after installing Perl.
977 C<pod2html> now allows specifying a cache directory.
981 C<s2p> has been completely rewritten in Perl. (It is in fact a full
982 implementation of sed in Perl: you can use the sed functionality by
983 using the C<psed> utility.)
987 C<xsubpp> now understands POD documentation embedded in the *.xs files.
991 C<xsubpp> now supports OUT keyword.
995 =head1 New Documentation
1001 perl56delta details the changes between the 5.005 release and the
1006 perlclib documents the internal replacements for standard C library
1007 functions. (Interesting only for extension writers and Perl core
1012 perldebtut is a Perl debugging tutorial.
1016 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1017 Note that unfortunately EBCDIC platforms that used to supported back in
1018 Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
1019 bring them back to the fold.
1023 perlintro is a gentle introduction to Perl.
1027 perliol documents the internals of PerlIO with layers.
1031 perlmodstyle is a style guide for writing modules.
1035 perlnewmod tells about writing and submitting a new module.
1039 perlpod has been rewritten to be clearer and to record the best
1040 practices gathered over the years.
1044 perlpodstyle is a more formal specification of the pod format,
1045 mainly of interest for writers of pod applications, not to
1046 people writing in pod.
1050 perlposix-bc explains using Perl on the POSIX-BC platform
1051 (an EBCDIC mainframe platform).
1055 perlretut is a regular expression tutorial.
1059 perlrequick is a regular expressions quick-start guide.
1060 Yes, much quicker than perlretut.
1064 perltodo has been updated.
1068 perltootc has been renamed as perltooc (to not to conflict
1069 with perltoot in filesystems restricted to "8.3" names)
1073 perluniintro is an introduction to using Unicode in Perl
1074 (perlunicode is more of a reference)
1078 perlutil explains the command line utilities packaged with the Perl
1083 The following platform-specific documents are available before
1084 the installation as README.I<platform>, and after the installation
1087 perlaix perlamiga perlapollo perlbeos perlbs2000
1088 perlce perlcygwin perldgux perldos perlepoc perlhpux
1089 perlhurd perlmachten perlmacos perlmint perlmpeix
1090 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1091 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1097 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1098 confusion with the Perl POSIX module.
1102 The documentation for the WinCE platform is called "CE", to avoid
1103 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1107 =head1 Performance Enhancements
1113 map() that changes the size of the list should now work faster.
1117 sort() has been changed to use mergesort internally as opposed to the
1118 earlier quicksort. For very small lists this may result in slightly
1119 slower sorting times, but in general the speedup should be at least
1120 20%. Additional bonuses are that the worst case behaviour of sort()
1121 is now better (in computer science terms it now runs in time O(N log N),
1122 as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
1123 and that sort() is now stable (meaning that elements with identical
1124 keys will stay ordered as they were before the sort).
1128 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1129 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1130 reasonably fast while producing a much better spread of values than
1131 the old hashing algorithm (originally by Chris Torek, later tweaked by
1132 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1133 all 3-char printable ASCII keys comes much closer to passing the
1134 DIEHARD random number generation tests. According to perlbench, this
1135 change has not affected the overall speed of Perl.
1139 unshift() should now be noticeably faster.
1143 =head1 Installation and Configuration Improvements
1145 =head2 Generic Improvements
1151 INSTALL now explains how you can configure Perl to use 64-bit
1152 integers even on non-64-bit platforms.
1156 Policy.sh policy change: if you are reusing a Policy.sh file
1157 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1158 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1159 them will now be changed to the new prefix, /foo/bar. (Previously
1160 only $prefix changed.) If you do not like this new behaviour,
1161 specify prefix, siteprefix, and vendorprefix explicitly.
1165 A new optional location for Perl libraries, otherlibdirs, is available.
1166 It can be used for example for vendor add-ons without disturbing Perl's
1167 own library directories.
1171 In many platforms the vendor-supplied 'cc' is too stripped-down to
1172 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1173 to be the case and 'cc' does not seem to be the GNU C compiler
1174 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1178 gcc needs to closely track the operating system release to avoid
1179 build problems. If Configure finds that gcc was built for a different
1180 operating system release than is running, it now gives a clearly visible
1181 warning that there may be trouble ahead.
1185 If binary compatibility with the 5.005 release is not wanted, Configure
1186 no longer suggests including the 5.005 modules in @INC.
1190 Configure C<-S> can now run non-interactively.
1194 configure.gnu now works with options with whitespace in them.
1198 installperl now outputs everything to STDERR.
1202 $Config{byteorder} is now computed dynamically (this is more robust
1203 with "fat binaries" where an executable image contains binaries for
1204 more than one binary platform.)
1208 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1209 get appended to the $Config{archname} (also known as $^O) anymore.
1210 Instead, if you explicitly choose not to use perlio (Configure command
1211 line option -Uuseperlio), you will get "-stdio" appended.
1215 Another change related to the architecture name is that "-64all"
1216 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1217 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1221 In AFS installations one can configure the root of the AFS to be
1222 somewhere else than the default F</afs> by using the Configure
1223 parameter C<-Dafsroot=/some/where/else>.
1227 APPLLIB_EXP, a less-know configuration-time definition, has been
1228 documented. It can be used to prepend site-specific directories
1229 to Perl's default search path (@INC), see INSTALL for information.
1233 The version of Berkeley DB used when the Perl (and, presumably, the
1234 DB_File extension) was built is now available as
1235 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1236 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1237 DB_VERSION_PATCH_CFG> from C.
1241 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1242 has been documented in INSTALL.
1246 If you have CPAN access (either network or a local copy such as a
1247 CD-ROM) you can during specify extra modules to Configure to build and
1248 install with Perl using the -Dextras=... option. See INSTALL for
1253 In addition to config.over a new override file, config.arch, is
1254 available. That is supposed to be used by hints file writers for
1255 architecture-wide changes (as opposed to config.over which is for
1260 For Perl developers several new make targets for profiling
1261 and debugging have been added, see L<perlhack>.
1267 Use of the F<gprof> tool to profile Perl has been documented in
1268 L<perlhack>. There is a make target called "perl.gprof" for
1269 generating a gprofiled Perl executable.
1273 If you have GCC 3, there is a make target called "perl.gcov" for
1274 creating a gcoved Perl executable for coverage analysis. See
1279 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1280 have been added, see L<perlhack> for more information about pixie and
1287 Guidelines of how to construct minimal Perl installations have
1288 been added to INSTALL.
1292 The Thread extension is now not built at all under ithreads
1293 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1294 Thread extension requires being Configured with C<-Duse5005threads>).
1296 But note that the Thread.pm interface is now shared by both
1301 =head2 New Or Improved Platforms
1303 For the list of platforms known to support Perl,
1304 see L<perlport/"Supported Platforms">.
1310 AIX dynamic loading should be now better supported.
1314 AIX should now work better with gcc, threads, and 64-bitness. Also the
1315 long doubles support in AIX should be better now. See L<perlaix>.
1319 After a long pause, AmigaOS has been verified to be happy with Perl.
1323 AtheOS (http://www.atheos.cx/) is a new platform.
1327 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1331 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1335 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1336 have been regained. Many test suite tests still fail and the
1337 co-existence of Unicode and EBCDIC isn't quite settled, but the
1338 situation is much better than with Perl 5.6. See L<perlos390>,
1339 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1343 Building perl with -Duseithreads or -Duse5005threads now works under
1344 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1345 need a thread library package installed. See README.hpux.
1349 MacOS Classic (MacPerl has of course been available since
1350 perl 5.004 but now the source code bases of standard Perl
1351 and MacPerl have been synchronised)
1355 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1356 filesystems. (The case-insensitivity confused the Perl build process.)
1360 NCR MP-RAS is now supported.
1364 NetWare from Novell is now supported. See L<perlnetware>.
1368 NonStop-UX is now supported.
1372 Amdahl UTS UNIX mainframe platform is now supported.
1376 WinCE is now supported. See L<perlce>.
1380 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1381 support for dynamic loading. This is not selected by default,
1382 however, you must specify -Dusedl in the arguments of Configure.
1386 =head1 Selected Bug Fixes
1388 Numerous memory leaks and uninitialized memory accesses have been hunted down.
1389 Most importantly anonymous subs used to leak quite a bit.
1395 Several debugger fixes: exit code now reflects the script exit code,
1396 condition C<"0"> now treated correctly, the C<d> command now checks
1397 line number, the C<$.> no longer gets corrupted, all debugger output now
1398 goes correctly to the socket if RemotePort is set.
1402 C<*foo{FORMAT}> now works.
1406 Lexical warnings now propagating correctly between scopes.
1410 Line renumbering with eval and C<#line> now works.
1414 Fixed numerous memory leaks, especially in eval "".
1418 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1419 return 27406, instead of 27047).
1423 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1424 more compatible with 5.005. Infinity is now recognised as a number.
1428 our() variables will not cause "will not stay shared" warnings.
1432 pack "Z" now correctly terminates the string with "\0".
1436 Fix password routines which in some shadow password platforms
1437 (e.g. HP-UX) caused getpwent() to return every other entry.
1441 printf() no longer resets the numeric locale to "C".
1445 C<q(a\\b)> now parses correctly as C<'a\\b'>.
1449 Printing quads (64-bit integers) with printf/sprintf now works
1450 without the q L ll prefixes (assuming you are on a quad-capable platform).
1454 Regular expressions on references and overloaded scalars now work.
1458 scalar() now forces scalar context even when used in void context.
1462 sort() arguments are now compiled in the right wantarray context
1463 (they were accidentally using the context of the sort() itself).
1467 Changed the POSIX character class C<[[:space:]]> to include the (very
1468 rare) vertical tab character. Added a new POSIX-ish character class
1469 C<[[:blank:]]> which stands for horizontal whitespace (currently,
1470 the space and the tab).
1474 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1475 in multiple threads simultaneously are now thread-safe.
1479 Allow read-only string on left hand side of non-modifying tr///.
1483 Several Unicode fixes (but still not perfect).
1489 BOMs (byte order marks) in the beginning of Perl files
1490 (scripts, modules) should now be transparently skipped.
1491 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1495 The character tables have been updated to Unicode 3.0.1.
1499 chr() for values greater than 127 now create utf8 when under use
1504 Comparing with utf8 data does not magically upgrade non-utf8 data into
1509 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1513 Concatenation with the C<.> operator or via variable interpolation,
1514 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1515 substitution with C<s///>, single-quoted UTF8, should now work--in
1520 The C<tr///> operator now works I<slightly> better but is still rather
1521 broken. Note that the C<tr///CU> functionality has been removed (but
1522 see pack('U0', ...)).
1526 vec() now refuses to deal with characters >255.
1530 Zero entries were missing from the Unicode classes like C<IsDigit>.
1534 chop(@list) in list context returned the characters chopped in
1535 reverse order. This has been reversed to be in the right order.
1539 The order of DESTROYs has been made more predictable.
1543 mkdir() now ignores trailing slashes in the directory name,
1544 as mandated by POSIX.
1548 Attributes (like :shared) didn't work with our().
1552 The PERL5OPT environment variable (for passing command line arguments
1553 to Perl) didn't work for more than a single group of options.
1557 The tainting behaviour of sprintf() has been rationalized. It does
1558 not taint the result of floating point formats anymore, making the
1559 behaviour consistent with that of string interpolation.
1563 All but the first argument of the IO syswrite() method are now optional.
1567 Tie::ARRAY SPLICE method was broken.
1571 vec() now tries to work with characters <= 255 when possible, but it leaves
1572 higher character values in place. In that case, if vec() was used to modify
1573 the string, it is no longer considered to be utf8-encoded.
1577 The autouse pragma didn't work for Multi::Part::Function::Names.
1581 The behaviour of non-decimal but numeric string constants such as
1582 "0x23" was platform-dependent: in some platforms that was seen as 35,
1583 in some as 0, in some as a floating point number (don't ask). This
1584 was caused by Perl using the operating system libraries in a situation
1585 where the result of the string to number conversion is undefined: now
1586 Perl consistently handles such strings as zero in numeric contexts.
1590 L<dprofpp> -R didn't work.
1594 PERL5OPT with embedded spaces didn't work.
1598 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
1602 Some versions of glibc have a broken modfl(). This affects builds
1603 with C<-Duselongdouble>. This version of Perl detects this brokenness
1604 and has a workaround for it. The glibc release 2.2.2 is known to have
1605 fixed the modfl() bug.
1609 Linux previously had problems related to sockaddrlen when using
1610 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
1614 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
1624 Borland C++ v5.5 is now a supported compiler that can build Perl.
1625 However, the generated binaries continue to be incompatible with those
1626 generated by the other supported compilers (GCC and Visual C++).
1630 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
1631 Other bugs in chdir() and Cwd::cwd() have also been fixed.
1635 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
1639 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
1643 The makefiles now provide a single switch to bulk-enable all the features
1644 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
1652 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1653 the Tk extension with 5.6.0.)
1657 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1658 when building the Perl binary. The only exception to this is SunOS 4.x,
1663 SOCKS support is now much more robust.
1667 If your file system supports symbolic links you can build Perl outside
1668 of the source directory by
1670 mkdir /tmp/perl/build/directory
1671 cd /tmp/perl/build/directory
1672 sh /path/to/perl/source/Configure -Dmksymlinks ...
1674 This will create in /tmp/perl/build/directory a tree of symbolic links
1675 pointing to files in /path/to/perl/source. The original files are left
1676 unaffected. After Configure has finished you can just say
1680 and Perl will be built and tested, all in /tmp/perl/build/directory.
1684 =head2 Platform Specific Changes and Fixes
1692 Perl now works on post-4.0 BSD/OSes.
1698 Setting C<$0> now works (as much as possible; see perlvar for details).
1704 Numerous updates; currently synchronised with Cygwin 1.1.4.
1710 EPOC update after Perl 5.6.0. See README.epoc.
1716 Perl now works on post-3.0 FreeBSDs.
1722 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1728 Numerous compilation flag and hint enhancements; accidental mixing
1729 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1735 Long doubles should now work (see INSTALL).
1741 Compilation of the standard Perl distribution in MacOS Classic should
1742 now work if you have the Metrowerks development environment and
1743 the missing Mac-specific toolkit bits. Contact the macperl mailing
1750 MPE/iX update after Perl 5.6.0. See README.mpeix.
1756 Perl now works on NetBSD/sparc.
1762 Now works with usethreads (see INSTALL).
1768 64-bitness using the Sun Workshop compiler now works.
1772 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1774 The operating system version letter now recorded in $Config{osvers}.
1775 Allow compiling with gcc (previously explicitly forbidden). Compiling
1776 with gcc still not recommended because buggy code results, even with
1783 Fixed various alignment problems that lead into core dumps either
1784 during build or later; no longer dies on math errors at runtime;
1785 now using full quad integers (64 bits), previously was using
1786 only 46 bit integers for speed.
1792 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
1793 (see INSTALL); now works with Perl's malloc.
1803 accept() no longer leaks memory.
1807 Better chdir() return value for a non-existent directory.
1811 New %ENV entries now propagate to subprocesses.
1815 $ENV{LIB} now used to search for libs under Visual C.
1819 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
1823 Allow REG_EXPAND_SZ keys in the registry.
1827 Can now send() from all threads, not just the first one.
1831 Fake signal handling reenabled, bugs and all.
1835 Less stack reserved per thread so that more threads can run
1836 concurrently. (Still 16M per thread.)
1840 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
1841 (works better when perl is running as service).
1845 Better UNC path handling under ithreads.
1849 wait() and waitpid() now work much better.
1853 winsock handle leak fixed.
1859 =head1 New or Changed Diagnostics
1865 All regular expression compilation error messages are now hopefully
1866 easier to understand both because the error message now comes before
1867 the failed regex and because the point of failure is now clearly
1868 marked by a C<E<lt>-- HERE> marker.
1872 The various "opened only for", "on closed", "never opened" warnings
1873 drop the C<main::> prefix for filehandles in the C<main> package,
1874 for example C<STDIN> instead of <main::STDIN>.
1878 The "Unrecognized escape" warning has been extended to include C<\8>,
1879 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
1883 Two new debugging options have been added: if you have compiled your
1884 Perl with debugging, you can use the -DT and -DR options to trace
1885 tokenising and to add reference counts to displaying variables,
1890 If an attempt to use a (non-blessed) reference as an array index
1891 is made, a warning is given.
1895 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
1896 now give a warning. This may be a problem for generated and evaled
1901 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
1902 using the C<"C"> format you will get an optional warning. Similarly
1903 for the C<"c"> format and a number less than -128 or more than 127.
1907 Certain regex modifiers such as C<(?o)> make sense only if applied to
1908 the entire regex. You will an optional warning if you try to do otherwise.
1912 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
1913 deprecated for a while. Now you will get an optional warning.
1917 =head1 Changed Internals
1923 perlapi.pod (a companion to perlguts) now attempts to document the
1928 You can now build a really minimal perl called microperl.
1929 Building microperl does not require even running Configure;
1930 C<make -f Makefile.micro> should be enough. Beware: microperl makes
1931 many assumptions, some of which may be too bold; the resulting
1932 executable may crash or otherwise misbehave in wondrous ways.
1933 For careful hackers only.
1937 Added rsignal(), whichsig(), do_join() to the publicised API.
1941 Made possible to propagate customised exceptions via croak()ing.
1945 Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
1949 Now xsubs can have attributes just like subs.
1953 Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
1954 For the full list of the available APIs see L<perlapi>.
1958 dTHR and djSP have been obsoleted; the former removed (because it's
1959 a no-op) and the latter replaced with dSP.
1963 PERL_OBJECT has been completely removed.
1967 The MAGIC constants (e.g. C<'P'>) have been macrofied
1968 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
1969 and maintainability.
1973 The regex compiler now maintains a structure that identifies nodes in
1974 the compiled bytecode with the corresponding syntactic features of the
1975 original regex expression. The information is attached to the new
1976 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
1977 complete information.
1981 The C code has been made much more C<gcc -Wall> clean. Some warning
1982 messages still remain in some platforms, so if you are compiling with
1983 gcc you may see some warnings about dubious practices. The warnings
1984 are being worked on.
1988 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
1992 Documentation on how to use the Perl source repository has been added
1993 to F<Porting/repository.pod>.
1997 There are now several profiling make targets
2001 The C<op_clear> and C<op_null> are now exported.
2005 =head1 Security Vulnerability Closed
2007 (This change was already made in 5.7.0 but bears repeating here.)
2009 A potential security vulnerability in the optional suidperl component
2010 of Perl was identified in August 2000. suidperl is neither built nor
2011 installed by default. As of November 2001 the only known vulnerable
2012 platform is Linux, most likely all Linux distributions. CERT and
2013 various vendors and distributors have been alerted about the vulnerability.
2014 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2015 for more information.
2017 The problem was caused by Perl trying to report a suspected security
2018 exploit attempt using an external program, /bin/mail. On Linux
2019 platforms the /bin/mail program had an undocumented feature which
2020 when combined with suidperl gave access to a root shell, resulting in
2021 a serious compromise instead of reporting the exploit attempt. If you
2022 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2023 suidperl is not installed, you are safe.
2025 The exploit attempt reporting feature has been completely removed from
2026 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2027 from all the Perl 5.7 releases), so that particular vulnerability
2028 isn't there anymore. However, further security vulnerabilities are,
2029 unfortunately, always possible. The suidperl functionality is most
2030 probably going to be removed in Perl 5.10. In any case, suidperl
2031 should only be used by security experts who know exactly what they are
2032 doing and why they are using suidperl instead of some other solution
2033 such as sudo (see http://www.courtesan.com/sudo/).
2037 Several new tests have been added, especially for the F<lib> subsection.
2039 The tests are now reported in a different order than in earlier Perls.
2040 (This happens because the test scripts from under t/lib have been moved
2041 to be closer to the library/extension they are testing.)
2043 =head1 Known Problems
2045 Note that unlike other sections in this document (which describe
2046 changes since 5.7.0) this section is cumulative containing known
2047 problems for all the 5.7 releases.
2055 In AIX 4.2 Perl extensions that use C++ functions that use statics
2056 may have problems in that the statics are not getting initialized.
2057 In newer AIX releases this has been solved by linking Perl with
2058 the libC_r library, but unfortunately in AIX 4.2 the said library
2059 has an obscure bug where the various functions related to time
2060 (such as time() and gettimeofday()) return broken values, and
2061 therefore in AIX 4.2 Perl is not linked against the libC_r.
2065 vac 5.0.0.0 May Produce Buggy Code For Perl
2067 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2068 resulting in few random tests failing, but when the failing tests
2069 are run by hand, they succeed. We suggest upgrading to at least
2070 vac version 5.0.1.0, that has been known to compile Perl correctly.
2071 "lslpp -L|grep vac.C" will tell you the vac version.
2075 =head2 Amiga Perl Invoking Mystery
2077 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2078 works, but for example C<bin:perl -v> doesn't. The exact reason is
2079 known but the current suspect is the F<ixemul> library.
2081 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2083 Don't panic. Read INSTALL 'make test' section instead.
2085 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2087 The subtests 11 and 12 sometimes fail and sometimes work.
2089 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2091 The lib/io_multihomed test may hang in HP-UX if Perl has been
2092 configured to be 64-bit. Because other 64-bit platforms do not hang in
2093 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2094 test attempts to create and connect to "multihomed" sockets (sockets
2095 which have multiple IP addresses).
2097 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2099 If perl is configured with -Duse64bitall, the successful result of the
2100 subtest 10 of lib/posix may arrive before the successful result of the
2101 subtest 9, which confuses the test harness so much that it thinks the
2104 =head2 Linux With Sfio Fails op/misc Test 48
2110 OS/390 has rather many test failures but the situation is actually
2111 better than it was in 5.6.0, it's just that so many new modules and
2112 tests have been added.
2114 Failed Test Stat Wstat Total Fail Failed List of Failed
2115 -----------------------------------------------------------------------------
2116 ../ext/B/Deparse.t 14 1 7.14% 14
2117 ../ext/B/Showlex.t 1 1 100.00% 1
2118 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2120 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2121 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2122 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2123 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2124 ../lib/warnings.t 434 1 0.23% 75
2125 ../lib/ExtUtils.t 27 1 3.70% 25
2126 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2127 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2128 ../lib/User/pwent.t 9 1 11.11% 4
2129 op/pat.t 660 6 0.91% 242-243 424-425
2131 op/split.t 0 9 ?? ?? % ??
2132 op/taint.t 174 3 1.72% 156 162 168
2133 op/tr.t 70 3 4.29% 50 58-59
2134 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2136 =head2 op/sprintf tests 129 and 130
2138 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2139 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2140 The failing platforms do not comply with the ANSI C Standard, line
2141 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2142 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2143 the printf format "%.0f", most often they produce "0" and "-0".)
2145 =head2 Failure of Thread tests
2147 B<Note that support for 5.005-style threading remains experimental.>
2149 The following tests are known to fail due to fundamental problems in
2150 the 5.005 threading implementation. These are not new failures--Perl
2151 5.005_0x has the same bugs, but didn't have these tests.
2154 t/lib/thr5005.t 19-20
2162 ext/POSIX/sigaction subtests 6 and 13 may fail.
2166 lib/ExtUtils may spuriously claim that subtest 28 failed,
2167 which is interesting since the test only has 27 tests.
2171 Numerous numerical test failures
2173 op/numconvert 209,210,217,218
2175 ext/Time/HiRes/HiRes 9
2176 lib/Math/BigInt/t/bigintpm 1145
2179 These tests fail because of yet unresolved floating point inaccuracies.
2185 There are a few known test failures, see L<perluts>.
2189 Rather many tests are failing in VMS but that actually more tests
2190 succeed in VMS than they used to, it's just that there are many,
2191 many more tests than there used to be.
2193 Here are the known failures from some compiler/platform combinations.
2195 DEC C V5.3-006 on OpenVMS VAX V6.2
2197 [-.ext.list.util.t]tainted..............FAILED on test 3
2198 [-.ext.posix]sigaction..................FAILED on test 7
2199 [-.ext.time.hires]hires.................FAILED on test 14
2200 [-.lib.file.find]taint..................FAILED on test 17
2201 [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
2202 [-.lib.test.simple.t]exit...............FAILED on test 1
2203 [.lib]vmsish............................FAILED on test 13
2204 [.op]sprintf............................FAILED on test 12
2205 Failed 8/399 tests, 91.23% okay.
2207 DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and
2208 Compaq C V6.2-008 on OpenVMS Alpha V7.1
2210 [-.ext.list.util.t]tainted..............FAILED on test 3
2211 [-.lib.file.find]taint..................FAILED on test 17
2212 [-.lib.test.simple.t]exit...............FAILED on test 1
2213 [.lib]vmsish............................FAILED on test 13
2214 Failed 4/399 tests, 92.48% okay.
2216 Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
2218 [-.ext.b]showlex........................FAILED on test 1
2219 [-.ext.list.util.t]tainted..............FAILED on test 3
2220 [-.lib.file.find]taint..................FAILED on test 17
2221 [-.lib.test.simple.t]exit...............FAILED on test 1
2222 [.lib]vmsish............................FAILED on test 13
2223 [.op]misc...............................FAILED on test 49
2224 Failed 6/401 tests, 92.77% okay.
2228 In multi-CPU boxes there are some problems with the I/O buffering:
2229 some output may appear twice.
2231 =head2 Localising a Tied Variable Leaks Memory
2234 tie my %tie_hash => 'Tie::StdHash';
2238 local($tie_hash{Foo}) = 1; # leaks
2240 Code like the above is known to leak memory every time the local()
2243 =head2 Self-tying of Arrays and Hashes Is Forbidden
2245 Self-tying of arrays and hashes is broken in rather deep and
2246 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2247 frustrated at the mysterious results (core dumps, most often) it is
2248 for now forbidden (you will get a fatal error even from an attempt).
2250 =head2 Variable Attributes are not Currently Usable for Tieing
2252 This limitation will hopefully be fixed in future. (Subroutine
2253 attributes work fine for tieing, see L<Attribute::Handlers>).
2255 =head2 Building Extensions Can Fail Because Of Largefiles
2257 Some extensions like mod_perl are known to have issues with
2258 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2259 default to 64 bits wide, where supported. Modules may fail to compile
2260 at all or compile and work incorrectly. Currently there is no good
2261 solution for the problem, but Configure now provides appropriate
2262 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2263 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2264 having problems can try configuring themselves without the
2265 largefileness. This is admittedly not a clean solution, and the
2266 solution may not even work at all. One potential failure is whether
2267 one can (or, if one can, whether it's a good idea) link together at
2268 all binaries with different ideas about file offsets, all this is
2271 =head2 The Compiler Suite Is Still Experimental
2273 The compiler suite is slowly getting better but is nowhere near
2276 =head2 The Long Double Support is Still Experimental
2278 The ability to configure Perl's numbers to use "long doubles",
2279 floating point numbers of hopefully better accuracy, is still
2280 experimental. The implementations of long doubles are not yet
2281 widespread and the existing implementations are not quite mature
2282 or standardised, therefore trying to support them is a rare
2283 and moving target. The gain of more precision may also be offset
2284 by slowdown in computations (more bits to move around, and the
2285 operations are more likely to be executed by less optimised
2288 =head1 Reporting Bugs
2290 If you find what you think is a bug, you might check the articles
2291 recently posted to the comp.lang.perl.misc newsgroup and the perl
2292 bug database at http://bugs.perl.org. There may also be
2293 information at http://www.perl.com/perl/, the Perl Home Page.
2295 If you believe you have an unreported bug, please run the B<perlbug>
2296 program included with your release. Be sure to trim your bug down
2297 to a tiny but sufficient test case. Your bug report, along with the
2298 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2299 analysed by the Perl porting team.
2303 The F<Changes> file for exhaustive details on what changed.
2305 The F<INSTALL> file for how to build Perl.
2307 The F<README> file for general stuff.
2309 The F<Artistic> and F<Copying> files for copyright information.
2313 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.