3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release
10 Many of the bug fixes in 5.8.0 were already seen in the 5.6.1
11 maintenance release since the two releases were kept closely
14 If you are upgrading from Perl 5.005_03, you might also want
15 to read L<perl56delta>.
17 =head1 Highlights In 5.8.0
23 Better Unicode support
27 New Thread Implementation
35 Better Numeric Accuracy
43 More Extensive Regression Testing
47 =head1 Incompatible Changes
49 =head2 64-bit platforms and malloc
51 If your pointers are 64 bits wide, the Perl malloc is no longer being
52 used because it does not work well with 8-byte pointers. Also,
53 usually the system mallocs on such platforms are much better optimized
54 for such large memory models than the Perl malloc. Some memory-hungry
55 Perl applications like the PDL don't work well with Perl's malloc.
56 Finally, other applications than Perl (like modperl) tend to prefer
57 the system malloc. Such platforms include Alpha and 64-bit HPPA,
60 =head2 AIX Dynaloading
62 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
63 dlopen interface of AIX instead of the old emulated interface. This
64 change will probably break backward compatibility with compiled
65 modules. The change was made to make Perl more compliant with other
66 applications like modperl which are using the AIX native interface.
68 =head2 Attributes for C<my> variables now handled at run-time.
70 The C<my EXPR : ATTRS> syntax now applies variable attributes at
71 run-time. (Subroutine and C<our> variables still get attributes applied
72 at compile-time.) See L<attributes> for additional details. In particular,
73 however, this allows variable attributes to be useful for C<tie> interfaces,
74 which was a deficiency of earlier releases. Note that the new semantics
75 doesn't work with the Attribute::Handlers module (as of version 0.76).
77 =head2 Socket Extension Dynamic in VMS
79 The Socket extension is now dynamically loaded instead of being
80 statically built in. This may or may not be a problem with ancient
81 TCP/IP stacks of VMS: we do not know since we weren't able to test
82 Perl in such configurations.
84 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
86 Perl now uses IEEE format (T_FLOAT) as the default internal floating
87 point format on OpenVMS Alpha, potentially breaking binary compatibility
88 with external libraries or existing data. G_FLOAT is still available as
89 a configuration option. The default on VAX (D_FLOAT) has not changed.
91 =head2 New Unicode Properties
93 Unicode I<scripts> are now supported. Scripts are similar to (and superior
94 to) Unicode I<blocks>. The difference between scripts and blocks is that
95 scripts are the glyphs used by a language or a group of languages, while
96 the blocks are more artificial groupings of (mostly) 256 characters based
97 on the Unicode numbering.
99 In general, scripts are more inclusive, but not universally so. For
100 example, while the script C<Latin> includes all the Latin characters and
101 their various diacritic-adorned versions, it does not include the various
102 punctuation or digits (since they are not solely C<Latin>).
104 A number of other properties are now supported, including C<\p{L&}>,
105 C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> and
106 C<\p{SpacePerl}> (along with their C<\P{...}> versions, of course).
107 See L<perlunicode> for details, and more additions.
109 The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
110 are now almost always optional. The only exception is that a C<In> prefix
111 is required to signify a Unicode block when a block name conflicts with a
112 script name. For example, C<\p{Tibetan}> refers to the script, while
113 C<\p{InTibetan}> refers to the block. When there is no name conflict, you
114 can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
115 to be safe, it's probably best to always use the C<In>).
117 =head2 Perl Parser Stress Tested
119 The Perl parser has been stress tested using both random input and
120 Markov chain input and the few found crashes and lockups have been
123 =head2 REF(...) Instead Of SCALAR(...)
125 A reference to a reference now stringifies as "REF(0x81485ec)" instead
126 of "SCALAR(0x81485ec)" in order to be more consistent with the return
129 =head2 pack/unpack D/F recycled
131 The undocumented pack/unpack template letters D/F have been recycled
132 for better use: now they stand for long double (if supported by the
133 platform) and NV (Perl internal floating point type). (They used
134 to be aliases for f/d, but you never knew that.)
142 The semantics of bless(REF, REF) were unclear and until someone proves
143 it to make some sense, it is forbidden.
147 The obsolete chat2 library that should never have been allowed
148 to escape the laboratory has been decommissioned.
152 The builtin dump() function has probably outlived most of its
153 usefulness. The core-dumping functionality will remain in future
154 available as an explicit call to C<CORE::dump()>, but in future
155 releases the behaviour of an unqualified C<dump()> call may change.
159 The very dusty examples in the eg/ directory have been removed.
160 Suggestions for new shiny examples welcome but the main issue is that
161 the examples need to be documented, tested and (most importantly)
166 The (bogus) escape sequences \8 and \9 now give an optional warning
167 ("Unrecognized escape passed through"). There is no need to \-escape
172 The list of filenames from glob() (or <...>) is now by default sorted
173 alphabetically to be csh-compliant (which is what happened before
174 in most UNIX platforms). (bsd_glob() does still sort platform
175 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
179 Spurious syntax errors generated in certain situations, when glob()
180 caused File::Glob to be loaded for the first time, have been fixed.
184 Although "you shouldn't do that", it was possible to write code that
185 depends on Perl's hashed key order (Data::Dumper does this). The new
186 algorithm "One-at-a-Time" produces a different hashed key order.
187 More details are in L</"Performance Enhancements">.
191 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
192 In future releases this may become a fatal error.
196 The C<package;> syntax (C<package> without an argument) has been
197 deprecated. Its semantics were never that clear and its
198 implementation even less so. If you have used that feature to
199 disallow all but fully qualified variables, C<use strict;> instead.
203 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
204 recognised but now cause fatal errors. The previous behaviour of
205 ignoring them by default and warning if requested was unacceptable
206 since it, in a way, falsely promised that the features could be used.
210 The current user-visible implementation of pseudo-hashes (the weird
211 use of the first array element) is deprecated starting from Perl 5.8.0
212 and will be removed in Perl 5.10.0, and the feature will be
213 implemented differently. Not only is the current interface rather
214 ugly, but the current implementation slows down normal array and hash
215 use quite noticeably. The C<fields> pragma interface will remain
220 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
224 After years of trying the suidperl is considered to be too complex to
225 ever be considered truly secure. The suidperl functionality is likely
226 to be removed in a future release.
230 The long deprecated uppercase aliases for the string comparison
231 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
235 The tr///C and tr///U features have been removed and will not return;
236 the interface was a mistake. Sorry about that. For similar
237 functionality, see pack('U0', ...) and pack('C0', ...).
241 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
242 The prototypes are now checked at compile-time for invalid characters.
243 An optional warning is generated ("Illegal character in prototype...")
244 but this may be upgraded to a fatal error in a future release.
248 =head1 Core Enhancements
250 =head2 PerlIO is Now The Default
256 IO is now by default done via PerlIO rather than system's "stdio".
257 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
258 handle's behaviour. Layers can be specified at open time via 3-arg
261 open($fh,'>:crlf :utf8', $path) || ...
263 or on already opened handles via extended C<binmode>:
265 binmode($fh,':encoding(iso-8859-7)');
267 The built-in layers are: unix (low level read/write), stdio (as in
268 previous Perls), perlio (re-implementation of stdio buffering in a
269 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
270 but available on any platform). A mmap layer may be available if
271 platform supports it (mostly UNIXes).
273 Layers to be applied by default may be specified via the 'open' pragma.
275 See L</"Installation and Configuration Improvements"> for the effects
276 of PerlIO on your architecture name.
280 File handles can be marked as accepting Perl's internal encoding of Unicode
281 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
283 open($fh,">:utf8","Uni.txt");
285 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
286 for you since it's not UTF-8 what you will be getting but instead
287 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
288 http://www.unicode.org/unicode/reports/tr16/ for more information.
289 In future releases this naming may change.
293 File handles can translate character encodings from/to Perl's internal
294 Unicode form on read/write via the ":encoding()" layer.
298 File handles can be opened to "in memory" files held in Perl scalars via:
300 open($fh,'>', \$variable) || ...
304 Anonymous temporary files are available without need to
305 'use FileHandle' or other module via
307 open($fh,"+>", undef) || ...
309 That is a literal undef, not an undefined value.
313 The list form of C<open> is now implemented for pipes (at least on UNIX):
315 open($fh,"-|", 'cat', '/etc/motd')
317 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
324 Perl used to be fragile in that signals arriving at inopportune moments
325 could corrupt Perl's internal state. Now Perl postpones handling of
326 signals until it's safe (between opcodes).
328 This change may have surprising side effects because signals no longer
329 interrupt Perl instantly. Perl will now first finish whatever it was
330 doing, like finishing an internal operation (like sort()) or an
331 external operation (like an I/O operation), and only then look at any
332 arrived signals (and before starting the next operation). No more corrupt
333 internal state since the current operation is always finished first,
334 but the signal may take more time to get heard.
336 =head2 Unicode Overhaul
338 Unicode in general should be now much more usable than in Perl 5.6.0
339 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
340 regular expressions should work now, Unicode in tr/// should work now,
341 Unicode in I/O should work now.
347 The Unicode Character Database coming with Perl has been upgraded
348 to Unicode 3.1.1. For more information, see http://www.unicode.org/.
352 For developers interested in enhancing Perl's Unicode capabilities:
353 almost all the UCD files are included with the Perl distribution in
354 the F<lib/unicore subdirectory>. The most notable omission, for space
355 considerations, is the Unihan database.
359 The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
360 C isblank(), that is, it contains only "horizontal whitespace" (the space
361 character is, the newline isn't), and the "SpacePerl" is the Unicode
362 equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
363 tabulator character, whereas C<\s> doesn't.)
365 See "New Unicode Properties" earlier in this document for additional
366 information on changes with Unicode properties.
370 =head2 Understanding of Numbers
372 In general a lot of fixing has happened in the area of Perl's
373 understanding of numbers, both integer and floating point. Since in
374 many systems the standard number parsing functions like C<strtoul()>
375 and C<atof()> seem to have bugs, Perl tries to work around their
376 deficiencies. This results hopefully in more accurate numbers.
378 Perl now tries internally to use integer values in numeric conversions
379 and basic arithmetics (+ - * /) if the arguments are integers, and
380 tries also to keep the results stored internally as integers.
381 This change leads to often slightly faster and always less lossy
382 arithmetics. (Previously Perl always preferred floating point numbers
385 =head2 Miscellaneous Changes
391 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
392 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
396 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
397 in multiple arguments.)
401 The builtin dump() now gives an optional warning
402 C<dump() better written as CORE::dump()>,
403 meaning that by default C<dump(...)> is resolved as the builtin
404 dump() which dumps core and aborts, not as (possibly) user-defined
405 C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
406 (The whole dump() feature is to considered deprecated, and possibly
407 removed/changed in future releases.)
411 chomp() and chop() have been demoted back to I<not> being overridable
412 because they cannot really be overridden-- the problem is that their
413 prototype cannot be expressed and therefore one really cannot write
414 replacements to override these builtins.
418 END blocks are now run even if you exit/die in a BEGIN block.
419 Internally, the execution of END blocks is now controlled by
420 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
421 behaviour for Perl embedders. This will default in 5.10. See
426 Formats now support zero-padded decimal fields.
430 Lvalue subroutines can now return C<undef> in list context.
431 However, the lvalue subroutine feature still remains experimental.
435 A lost warning "Can't declare ... dereference in my" has been
436 restored (Perl had it earlier but it became lost in later releases.)
440 A new special regular expression variable has been introduced:
441 C<$^N>, which contains the most-recently closed group (submatch).
445 C<no Module;> now works even if there is no "sub unimport" in the Module.
449 The numerical comparison operators return C<undef> if either operand
450 is a NaN. Previously the behaviour was unspecified.
454 The following builtin functions are now overridable: each(), keys(),
455 pop(), push(), shift(), splice(), unshift().
459 C<pack() / unpack()> now can group template letters with C<()> and then
460 apply repetition/count modifiers on the groups.
464 C<pack() / unpack()> can now process the Perl internal numeric types:
465 IVs, UVs, NVs-- and also long doubles, if supported by the platform.
466 The template letters are C<j>, C<J>, C<F>, and C<D>.
470 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
474 my __PACKAGE__ $obj now works.
478 The printf() and sprintf() now support parameter reordering using the
479 C<%\d+\$> and C<*\d+\$> syntaxes. For example
481 print "%2\$s %1\$s\n", "foo", "bar";
483 will print "bar foo\n". This feature helps in writing
484 internationalised software, and in general when the order
485 of the parameters can vary.
489 prototype(\&) is now available.
493 prototype(\[$@%&]) is now available to implicitly create references
494 (useful for example if you want to emulate the tie() interface).
498 A new command-line option, C<-t> is available. It is the
499 little brother of C<-T>: instead of dieing on taint violations,
500 lexical warnings are given. B<This is only meant as a temporary
501 debugging aid while securing the code of old legacy applications.
502 This is not a substitute for -T.>
506 In other taint news, the C<exec LIST> and C<system LIST> have now been
507 considered too risky (think C<exec @ARGV>: it can start any program
508 with any arguments), and now the said forms cause a warning.
509 You should carefully launder the arguments to guarantee their
510 validity. In future releases of Perl the forms will become fatal
511 errors so consider starting laundering now.
515 If tr/// is just counting characters, it doesn't attempt to
520 untie() will now call an UNTIE() hook if it exists. See L<perltie>
525 L<utime> now supports C<utime undef, undef, @files> to change the
526 file timestamps to the current time.
530 The rules for allowing underscores (underbars) in numeric constants
531 have been relaxed and simplified: now you can have an underscore
532 simply B<between digits>.
536 =head1 Modules and Pragmata
538 =head2 New Modules and Pragmata
544 C<Attribute::Handlers> allows a class to define attribute handlers.
547 use Attribute::Handlers;
548 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
550 # later, in some package using or inheriting from MyPack...
552 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
554 Both variables and routines can have attribute handlers. Handlers can
555 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
556 exact compilation phase (BEGIN, CHECK, INIT, or END).
560 B<B::Concise> is a new compiler backend for walking the Perl syntax
561 tree, printing concise info about ops, from Stephen McCamant. The
562 output is highly customisable. See L<B::Concise>.
566 C<Class::ISA> for reporting the search path for a class's ISA tree,
567 by Sean Burke, has been added. See L<Class::ISA>.
571 C<Cwd> has now a split personality: if possible, an XS extension is
572 used, (this will hopefully be faster, more secure, and more robust)
573 but if not possible, the familiar Perl implementation is used.
577 C<Devel::PPPort>, originally from Kenneth Albanowski and now
578 maintained by Paul Marquess, has been added. It is primarily used
579 by C<h2xs> to enhance portability of XS modules between different
584 C<Digest>, frontend module for calculating digests (checksums), from
585 Gisle Aas, has been added. See L<Digest>.
589 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
590 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
592 use Digest::MD5 'md5_hex';
594 $digest = md5_hex("Thirsty Camel");
596 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
598 NOTE: the C<MD5> backward compatibility module is deliberately not
599 included since its further use is discouraged.
603 C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
604 between different character encodings. Support for Unicode,
605 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
606 compiled in to the module. Several other encodings (like Japanese,
607 Chinese, and MacIntosh encodings) are included and will be loaded at
608 runtime. See L<Encode>.
610 Any encoding supported by Encode module is also available to the
611 ":encoding()" layer if PerlIO is used.
615 C<I18N::Langinfo> can be use to query locale information.
616 See L<I18N::Langinfo>.
620 C<I18N::LangTags> has functions for dealing with RFC3066-style
621 language tags, by Sean Burke. See L<I18N::LangTags>.
625 C<ExtUtils::Constant> is a new tool for extension writers for
626 generating XS code to import C header constants, by Nicholas Clark.
627 See L<ExtUtils::Constant>.
631 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
632 from Damian Conway. See L<Filter::Simple>.
638 use Filter::Simple sub {
639 while (my ($from, $to) = splice @_, 0, 2) {
648 use MyFilter qr/red/ => 'green';
650 print "red\n"; # this code is filtered, will print "green\n"
651 print "bored\n"; # this code is filtered, will print "bogreen\n"
655 print "red\n"; # this code is not filtered, will print "red\n"
659 C<File::Temp> allows one to create temporary files and directories in
660 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
664 C<Filter::Util::Call> provides you with the framework to write
665 I<Source Filters> in Perl, from Paul Marquess. For most uses the
666 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
670 C<if> is a new pragma for conditional inclusion of modules, from
675 L<libnet> is a collection of perl5 modules related to network
676 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
677 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
679 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
683 C<List::Util> is a selection of general-utility list subroutines, like
684 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
688 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
689 C<Locale::Language>, from Neil Bowers, have been added. They provide the
690 codes for various locale standards, such as "fr" for France, "usd" for
691 US Dollar, and "jp" for Japanese.
695 $country = code2country('jp'); # $country gets 'Japan'
696 $code = country2code('Norway'); # $code gets 'no'
698 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
699 and L<Locale::Language>.
703 C<Locale::Maketext> is localization framework from Sean Burke. See
704 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
705 article about software localization, originally published in The Perl
706 Journal #13, republished here with kind permission.
710 C<Memoize> can make your functions faster by trading space for time,
711 from Mark-Jason Dominus. See L<Memoize>.
715 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
716 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
721 $encoded = encode_base64('Aladdin:open sesame');
722 $decoded = decode_base64($encoded);
724 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
730 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
731 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
732 Extensions)>, from Gisle Aas.
734 use MIME::QuotedPrint;
736 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
737 $decoded = decode_qp($encoded);
739 print $encoded, "\n"; # "Smiley in Unicode: =263A"
741 MIME::QuotedPrint has been enhanced to provide the basic methods
742 necessary to use it with PerlIO::Via as in :
744 use MIME::QuotedPrint;
745 open($fh,">Via(MIME::QuotedPrint)",$path);
747 See L<MIME::QuotedPrint>.
751 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
756 C<open> is a new pragma for setting the default I/O disciplines
761 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
762 Perl scalars as discussed above, from Nick Ing-Simmons. It also
763 serves as an example of a loadable PerlIO layer. Other future
764 possibilities include PerlIO::Array and PerlIO::Code.
765 See L<PerlIO::Scalar>.
769 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
770 functionality provided by a class (typically implemented in perl
771 code), from Nick Ing-Simmons.
773 use MIME::QuotedPrint;
774 open($fh,">Via(MIME::QuotedPrint)",$path);
776 This will automatically convert everything output to C<$fh>
777 to Quoted-Printable. See L<PerlIO::Via>.
781 C<Pod::ParseLink>, by Russ Allbery, has been added,
782 to parse LZ<><> links in pods as described in the new
787 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
788 It converts POD data to formatted overstrike text.
789 See L<Pod::Text::Overstrike>.
793 C<Scalar::Util> is a selection of general-utility scalar subroutines,
794 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
798 C<sort> is a new pragma for controlling the behaviour of sort().
802 C<Storable> gives persistence to Perl data structures by allowing the
803 storage and retrieval of Perl data to and from files in a fast and
804 compact binary format, from Raphael Manfredi. See L<Storable>.
808 C<Switch>, from Damian Conway, has been added. Just by saying
812 you have C<switch> and C<case> available in Perl.
818 case 1 { print "number 1" }
819 case "a" { print "string a" }
820 case [1..10,42] { print "number in list" }
821 case (@array) { print "number in list" }
822 case /\w+/ { print "pattern" }
823 case qr/\w+/ { print "pattern" }
824 case (%hash) { print "entry in hash" }
825 case (\%hash) { print "entry in hash" }
826 case (\&sub) { print "arg to subroutine" }
827 else { print "previous case not true" }
834 C<Test::More> is yet another framework for writing test scripts,
835 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
839 C<Test::Simple> has basic utilities for writing tests, by Michael
840 Schwern. See L<Test::Simple>.
844 C<Text::Balanced> has been added, for extracting delimited text
845 sequences from strings, from Damian Conway.
847 use Text::Balanced 'extract_delimited';
849 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
851 $a will be "'never say never'", $b will be ', he never said'.
853 In addition to extract_delimited() there are also extract_bracketed(),
854 extract_quotelike(), extract_codeblock(), extract_variable(),
855 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
856 gen_extract_tagged(). With these you can implement rather advanced
857 parsing algorithms. See L<Text::Balanced>.
861 C<threads> is an interface to interpreter threads, by Arthur Bergman.
862 Interpreter threads (ithreads) is the new thread model introduced in
863 Perl 5.6 but only available as an internal interface for extension
864 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
868 C<threads::shared> allows data sharing for interpreter threads, from
869 Arthur Bergman. In the ithreads model any data sharing between
870 threads must be explicit, as opposed to the old 5.005 thread model
871 where data sharing was implicit. See L<threads::shared>.
875 C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
880 C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
884 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
885 references (unlike the standard Tie::RefHash) The module is contained
886 within Tie::RefHash, see L<Tie::RefHash>.
890 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
891 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
895 C<Unicode::UCD> offers a querying interface to the Unicode Character
896 Database. See L<Unicode::UCD>.
900 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
901 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
905 C<Unicode::Normalize> implements the various Unicode normalization
906 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
910 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
911 typemaps. Nothing gets installed but for extension writers the code
916 =head2 Updated And Improved Modules and Pragmata
922 The following independently supported modules have been updated to the
923 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
924 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
925 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
926 Term::ANSIColor, Test, Text-Tabs+Wrap.
930 The attributes::reftype() now works on tied arguments.
934 AutoLoader can now be disabled with C<no AutoLoader;>.
938 B::Deparse has been significantly enhanced. It now can deparse almost
939 all of the standard test suite (so that the tests still succeed).
940 There is a make target "test.deparse" for trying this out.
944 Class::Struct can now define the classes in compile time.
948 Class::Struct now assigns the array/hash element if the accessor
949 is called with an array/hash element as the B<sole> argument.
953 Data::Dumper has now an option to sort hashes.
957 Data::Dumper has now an option to dump code references
962 DB_File now supports newer Berkeley DB versions, among
967 The English module can now be used without the infamous performance
970 use English '-no_match_vars';
972 (Assuming, of course, that one doesn't need the troublesome variables
973 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
974 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
978 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
979 new-style constant dispatch section (see L<ExtUtils::Constant>).
980 This means that they will be more robust and hopefully faster.
984 File::Find now chdir()s correctly when chasing symbolic links.
988 File::Find now has pre- and post-processing callbacks. It also
989 correctly changes directories when chasing symbolic links. Callbacks
990 (naughtily) exiting with "next;" instead of "return;" now work.
994 File::Find is now (again) reentrant. It also has been made
999 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1000 prototype mismatch with CORE::glob().
1004 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1005 the returned list of filenames.
1009 Devel::Peek now has an interface for the Perl memory statistics
1010 (this works only if you are using perl's malloc, and if you have
1011 compiled with debugging).
1015 IPC::Open3 now allows the use of numeric file descriptors.
1019 IO::Socket has now atmark() method, which returns true if the socket
1020 is positioned at the out-of-band mark. The method is also exportable
1021 as a sockatmark() function.
1025 IO::Socket::INET has support for ReusePort option (if your platform
1026 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
1027 you may want to prefer ReuseAddr.
1031 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
1032 that the operating system will make one up.)
1036 use lib now works identically to @INC. Removing directories
1037 with 'no lib' now works.
1041 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1042 leads into better portability.
1046 Math::BigFloat and Math::BigInt have undergone a full rewrite.
1047 They are now magnitudes faster, and they support various
1048 bignum libraries such as GMP and PARI as their backends.
1052 Math::Complex handles inf, NaN etc., better.
1056 Net::Ping has been muchly enhanced. Multihoming is now supported.
1057 There is now "external" protocol which uses Net::Ping::External module
1058 which runs external ping(1) and parses the output. A version of
1059 Net::Ping::External is available in CPAN.
1063 POSIX::sigaction() is now much more flexible and robust.
1064 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1065 handlers, installing new handlers was not atomic.
1069 In Safe the C<%INC> now localised in a Safe compartment so that
1074 In SDBM_File on dosish platforms, some keys went missing because of
1075 lack of support for files with "holes". A workaround for the problem
1080 In Search::Dict one can now have a pre-processing hook for the
1081 lines being searched.
1085 The Shell module now has an OO interface.
1089 The Test module has been significantly enhanced.
1093 The vars pragma now supports declaring fully qualified variables.
1094 (Something that C<our()> does not and will not support.)
1098 The C<utf8::> name space (as in the pragma) provides various
1099 Perl-callable functions to provide low level access to Perl's
1100 internal Unicode representation. At the moment only length()
1101 has been implemented.
1105 =head1 Utility Changes
1111 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1116 F<emacs/e2ctags.pl> is now much faster.
1120 C<h2ph> now supports C trigraphs.
1124 C<h2xs> now produces a template README.
1128 C<h2xs> now uses C<Devel::PPort> for better portability between
1129 different versions of Perl.
1133 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
1134 newly created extensions that define constants. Since the new code is
1135 more correct (if you have two constants where the first one is a
1136 prefix of the second one, the first constant B<never> gets defined),
1137 less lossy (it uses integers for integer constant, as opposed to the
1138 old code that used floating point numbers even for integer constants),
1139 and slightly faster, you might want to consider regenerating your
1140 extension code (the new scheme makes regenerating easy).
1141 L<h2xs> now also supports C trigraphs.
1145 C<libnetcfg> has been added to configure the libnet.
1149 C<perlbug> is now much more robust. It also sends the bug report to
1150 perl.org, not perl.com.
1154 C<perlcc> has been rewritten and its user interface (that is,
1155 command line) is much more like that of the UNIX C compiler, cc.
1156 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1160 C<perlivp> is a new Installation Verification Procedure utility
1161 for running any time after installing Perl.
1165 C<pod2html> now allows specifying a cache directory.
1169 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1170 implementation of sed in Perl: you can use the sed functionality by
1171 using the C<psed> utility.)
1175 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1179 C<xsubpp> now supports OUT keyword.
1183 =head1 New Documentation
1189 perl56delta details the changes between the 5.005 release and the
1194 perlclib documents the internal replacements for standard C library
1195 functions. (Interesting only for extension writers and Perl core
1200 perldebtut is a Perl debugging tutorial.
1204 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1208 perlintro is a gentle introduction to Perl.
1212 perliol documents the internals of PerlIO with layers.
1216 perlmodstyle is a style guide for writing modules.
1220 perlnewmod tells about writing and submitting a new module.
1224 perlpacktut is a pack() tutorial.
1228 perlpod has been rewritten to be clearer and to record the best
1229 practices gathered over the years.
1233 perlpodspec is a more formal specification of the pod format,
1234 mainly of interest for writers of pod applications, not to
1235 people writing in pod.
1239 perlretut is a regular expression tutorial.
1243 perlrequick is a regular expressions quick-start guide.
1244 Yes, much quicker than perlretut.
1248 perltodo has been updated.
1252 perltootc has been renamed as perltooc (to not to conflict
1253 with perltoot in filesystems restricted to "8.3" names)
1257 perluniintro is an introduction to using Unicode in Perl.
1258 (perlunicode is more of a detailed reference and background
1263 perlutil explains the command line utilities packaged with the Perl
1268 The following platform-specific documents are available before
1269 the installation as README.I<platform>, and after the installation
1272 perlaix perlamiga perlapollo perlbeos perlbs2000
1273 perlce perlcygwin perldgux perldos perlepoc perlhpux
1274 perlhurd perlmachten perlmacos perlmint perlmpeix
1275 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1276 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1282 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1283 confusion with the Perl POSIX module.
1287 The documentation for the WinCE platform is called "CE", to avoid
1288 confusion with the perlwin32 documentation on 8.3-restricted filesystems.
1292 =head1 Performance Enhancements
1298 map() could get pathologically slow when the result list it generates
1299 is larger than the source list. The performance has been improved for
1304 sort() has been changed to use primarily mergesort internally as
1305 opposed to the earlier quicksort. For very small lists this may
1306 result in slightly slower sorting times, but in general the speedup
1307 should be at least 20%. Additional bonuses are that the worst case
1308 behaviour of sort() is now better (in computer science terms it now
1309 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1310 worst-case run time behaviour), and that sort() is now stable
1311 (meaning that elements with identical keys will stay ordered as they
1312 were before the sort). See the C<sort> pragma for information.
1314 The story in more detail: suppose you want to serve yourself a little
1317 @digits = ( 3,1,4,1,5,9 );
1319 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1320 Which C<1> comes first is hard to know, since one C<1> looks pretty
1321 much like any other. You can regard this as totally trivial,
1322 or somewhat profound. However, if you just want to sort the even
1323 digits ahead of the odd ones, then what will
1325 sort { ($a % 2) <=> ($b % 2) } @digits;
1327 yield? The only even digit, C<4>, will come first. But how about
1328 the odd numbers, which all compare equal? With the quicksort algorithm
1329 used to implement Perl 5.6 and earlier, the order of ties is left up
1330 to the sort. So, as you add more and more digits of Pi, the order
1331 in which the sorted even and odd digits appear will change.
1332 and, for sufficiently large slices of Pi, the quicksort algorithm
1333 in Perl 5.8 won't return the same results even if reinvoked with the
1334 same input. The justification for this rests with quicksort's
1335 worst case behavior. If you run
1337 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1339 (something you might approximate if you wanted to merge two sorted
1340 arrays using sort), doubling $N doesn't just double the quicksort time,
1341 it I<quadruples> it. Quicksort has a worst case run time that can
1342 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1343 on patterns that may well arise in normal use. You won't notice this
1344 for small arrays, but you I<will> notice it with larger arrays,
1345 and you may not live long enough for the sort to complete on arrays
1346 of a million elements. So the 5.8 quicksort scrambles large arrays
1347 before sorting them, as a statistical defence against quadratic behaviour.
1348 But that means if you sort the same large array twice, ties may be
1349 broken in different ways.
1351 Because of the unpredictability of tie-breaking order, and the quadratic
1352 worst-case behaviour, quicksort was I<almost> replaced completely with
1353 a stable mergesort. I<Stable> means that ties are broken to preserve
1354 the original order of appearance in the input array. So
1356 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1358 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1359 appear in the output in the same order they appeared in the input.
1360 Mergesort has worst case O(NlogN) behaviour, the best value
1361 attainable. And, ironically, this mergesort does particularly
1362 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1363 in O(N) time. But quicksort was rescued at the last moment because
1364 it is faster than mergesort on certain inputs and platforms.
1365 For example, if you really I<don't> care about the order of even
1366 and odd digits, quicksort will run in O(N) time; it's very good
1367 at sorting many repetitions of a small number of distinct elements.
1368 The quicksort divide and conquer strategy works well on platforms
1369 with relatively small, very fast, caches. Eventually, the problem gets
1370 whittled down to one that fits in the cache, from which point it
1371 benefits from the increased memory speed.
1373 Quicksort was rescued by implementing a sort pragma to control aspects
1374 of the sort. The B<stable> subpragma forces stable behaviour,
1375 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1376 subpragmas are heavy-handed ways to select the underlying implementation.
1377 The leading C<_> is a reminder that these subpragmas may not survive
1378 beyond 5.8. More appropriate mechanisms for selecting the implementation
1379 exist, but they wouldn't have arrived in time to save quicksort.
1383 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1384 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1385 reasonably fast while producing a much better spread of values than
1386 the old hashing algorithm (originally by Chris Torek, later tweaked by
1387 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1388 all 3-char printable ASCII keys comes much closer to passing the
1389 DIEHARD random number generation tests. According to perlbench, this
1390 change has not affected the overall speed of Perl.
1394 unshift() should now be noticeably faster.
1398 =head1 Installation and Configuration Improvements
1400 =head2 Generic Improvements
1406 INSTALL now explains how you can configure Perl to use 64-bit
1407 integers even on non-64-bit platforms.
1411 Policy.sh policy change: if you are reusing a Policy.sh file
1412 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1413 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1414 them will now be changed to the new prefix, /foo/bar. (Previously
1415 only $prefix changed.) If you do not like this new behaviour,
1416 specify prefix, siteprefix, and vendorprefix explicitly.
1420 A new optional location for Perl libraries, otherlibdirs, is available.
1421 It can be used for example for vendor add-ons without disturbing Perl's
1422 own library directories.
1426 In many platforms the vendor-supplied 'cc' is too stripped-down to
1427 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1428 to be the case and 'cc' does not seem to be the GNU C compiler
1429 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1433 gcc needs to closely track the operating system release to avoid
1434 build problems. If Configure finds that gcc was built for a different
1435 operating system release than is running, it now gives a clearly visible
1436 warning that there may be trouble ahead.
1440 If binary compatibility with the 5.005 release is not wanted, Configure
1441 no longer suggests including the 5.005 modules in @INC.
1445 Configure C<-S> can now run non-interactively.
1449 Configure support for pdp11-style memory models has been removed due
1454 configure.gnu now works with options with whitespace in them.
1458 installperl now outputs everything to STDERR.
1462 $Config{byteorder} is now computed dynamically (this is more robust
1463 with "fat binaries" where an executable image contains binaries for
1464 more than one binary platform.)
1468 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1469 get appended to the $Config{archname} (also known as $^O) anymore.
1470 Instead, if you explicitly choose not to use perlio (Configure command
1471 line option -Uuseperlio), you will get "-stdio" appended.
1475 Another change related to the architecture name is that "-64all"
1476 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1477 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1481 In AFS installations one can configure the root of the AFS to be
1482 somewhere else than the default F</afs> by using the Configure
1483 parameter C<-Dafsroot=/some/where/else>.
1487 APPLLIB_EXP, a less-know configuration-time definition, has been
1488 documented. It can be used to prepend site-specific directories
1489 to Perl's default search path (@INC), see INSTALL for information.
1493 The version of Berkeley DB used when the Perl (and, presumably, the
1494 DB_File extension) was built is now available as
1495 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1496 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1497 DB_VERSION_PATCH_CFG> from C.
1501 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1502 has been documented in INSTALL.
1506 If you have CPAN access (either network or a local copy such as a
1507 CD-ROM) you can during specify extra modules to Configure to build and
1508 install with Perl using the -Dextras=... option. See INSTALL for
1513 In addition to config.over a new override file, config.arch, is
1514 available. That is supposed to be used by hints file writers for
1515 architecture-wide changes (as opposed to config.over which is for
1520 If your file system supports symbolic links you can build Perl outside
1521 of the source directory by
1523 mkdir /tmp/perl/build/directory
1524 cd /tmp/perl/build/directory
1525 sh /path/to/perl/source/Configure -Dmksymlinks ...
1527 This will create in /tmp/perl/build/directory a tree of symbolic links
1528 pointing to files in /path/to/perl/source. The original files are left
1529 unaffected. After Configure has finished you can just say
1533 and Perl will be built and tested, all in /tmp/perl/build/directory.
1537 For Perl developers several new make targets for profiling
1538 and debugging have been added, see L<perlhack>.
1544 Use of the F<gprof> tool to profile Perl has been documented in
1545 L<perlhack>. There is a make target called "perl.gprof" for
1546 generating a gprofiled Perl executable.
1550 If you have GCC 3, there is a make target called "perl.gcov" for
1551 creating a gcoved Perl executable for coverage analysis. See
1556 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1557 have been added, see L<perlhack> for more information about pixie and
1564 Guidelines of how to construct minimal Perl installations have
1565 been added to INSTALL.
1569 The Thread extension is now not built at all under ithreads
1570 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1571 Thread extension requires being Configured with C<-Duse5005threads>).
1573 But note that the Thread.pm interface is now shared by both
1578 =head2 New Or Improved Platforms
1580 For the list of platforms known to support Perl,
1581 see L<perlport/"Supported Platforms">.
1587 AIX dynamic loading should be now better supported.
1591 AIX should now work better with gcc, threads, and 64-bitness. Also the
1592 long doubles support in AIX should be better now. See L<perlaix>.
1596 After a long pause, AmigaOS has been verified to be happy with Perl.
1600 AtheOS (http://www.atheos.cx/) is a new platform.
1604 BeOS has been reclaimed.
1608 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1612 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1616 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1617 have been regained. Many test suite tests still fail and the
1618 co-existence of Unicode and EBCDIC isn't quite settled, but the
1619 situation is much better than with Perl 5.6. See L<perlos390>,
1620 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1624 Building perl with -Duseithreads or -Duse5005threads now works under
1625 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1626 need a thread library package installed. See README.hpux.
1630 MacOS Classic (MacPerl has of course been available since
1631 perl 5.004 but now the source code bases of standard Perl
1632 and MacPerl have been synchronised)
1636 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1637 filesystems. (The case-insensitivity confused the Perl build process.)
1641 NCR MP-RAS is now supported.
1645 All the NetBSD specific patches (except for the installation
1646 specific ones) have been merged back to the main distribution.
1650 NetWare from Novell is now supported. See L<perlnetware>.
1654 NonStop-UX is now supported.
1658 NEC SUPER-UX is now supported.
1662 All the OpenBSD specific patches (except for the installation
1663 specific ones) have been merged back to the main distribution.
1667 Perl has been tested with the GNU pth userlevel thread package
1668 ( http://www.gnu.org/software/pth/pth.html ) . All but one thread
1669 test worked, and that one failure was because of test results arriving
1670 in unexpected order.
1674 Amdahl UTS UNIX mainframe platform is now supported.
1678 WinCE is now supported. See L<perlce>.
1682 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1683 support for dynamic loading. This is not selected by default,
1684 however, you must specify -Dusedl in the arguments of Configure.
1688 =head1 Selected Bug Fixes
1690 Numerous memory leaks and uninitialized memory accesses have been
1691 hunted down. Most importantly anonymous subs used to leak quite
1698 The autouse pragma didn't work for Multi::Part::Function::Names.
1702 caller() could cause core dumps in certain situations. Carp was sometimes
1703 affected by this problem.
1707 chop(@list) in list context returned the characters chopped in
1708 reverse order. This has been reversed to be in the right order.
1712 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1713 when building the Perl binary. The only exception to this is SunOS 4.x,
1718 The behaviour of non-decimal but numeric string constants such as
1719 "0x23" was platform-dependent: in some platforms that was seen as 35,
1720 in some as 0, in some as a floating point number (don't ask). This
1721 was caused by Perl using the operating system libraries in a situation
1722 where the result of the string to number conversion is undefined: now
1723 Perl consistently handles such strings as zero in numeric contexts.
1727 The order of DESTROYs has been made more predictable.
1731 Several debugger fixes: exit code now reflects the script exit code,
1732 condition C<"0"> now treated correctly, the C<d> command now checks
1733 line number, the C<$.> no longer gets corrupted, all debugger output
1734 now goes correctly to the socket if RemotePort is set.
1738 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1739 when statically building extensions into perl. This has been corrected.
1743 L<dprofpp> -R didn't work.
1747 C<*foo{FORMAT}> now works.
1750 Infinity is now recognized as a number.
1754 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1755 the Tk extension with 5.6.0.)
1759 Lexicals I: lexicals outside an eval "" weren't resolved
1760 correctly inside a subroutine definition inside the eval "" if they
1761 were not already referenced in the top level of the eval""ed code.
1765 Lexicals II: lexicals leaked at file scope into subroutines that
1766 were declared before the lexicals.
1770 Lexical warnings now propagating correctly between scopes
1771 and into C<eval "...">.
1775 C<use warnings qw(FATAL all)> did not work as intended. This has been
1780 warnings::enabled() now reports the state of $^W correctly if the caller
1781 isn't using lexical warnings.
1785 Line renumbering with eval and C<#line> now works.
1789 Fixed numerous memory leaks, especially in eval "".
1793 mkdir() now ignores trailing slashes in the directory name,
1794 as mandated by POSIX.
1798 Some versions of glibc have a broken modfl(). This affects builds
1799 with C<-Duselongdouble>. This version of Perl detects this brokenness
1800 and has a workaround for it. The glibc release 2.2.2 is known to have
1801 fixed the modfl() bug.
1805 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1806 return 27406, instead of 27047).
1810 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1811 more compatible with 5.005. Infinity is now recognised as a number.
1815 Numeric conversions did not recognize changes in the string value
1816 properly in certain circumstances.
1820 Attributes (like :shared) didn't work with our().
1824 our() variables will not cause "will not stay shared" warnings.
1828 "our" variables of the same name declared in two sibling blocks
1829 resulted in bogus warnings about "redeclaration" of the variables.
1830 The problem has been corrected.
1834 pack "Z" now correctly terminates the string with "\0".
1838 Fix password routines which in some shadow password platforms
1839 (e.g. HP-UX) caused getpwent() to return every other entry.
1843 The PERL5OPT environment variable (for passing command line arguments
1844 to Perl) didn't work for more than a single group of options.
1848 PERL5OPT with embedded spaces didn't work.
1852 printf() no longer resets the numeric locale to "C".
1856 C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1860 pos() did not return the correct value within s///ge in earlier
1861 versions. This is now handled correctly.
1865 Printing quads (64-bit integers) with printf/sprintf now works
1866 without the q L ll prefixes (assuming you are on a quad-capable platform).
1870 Regular expressions on references and overloaded scalars now work.
1874 Right-hand side magic (GMAGIC) could in many cases such as string
1875 concatenation be invoked too many times.
1879 scalar() now forces scalar context even when used in void context.
1883 SOCKS support is now much more robust.
1887 sort() arguments are now compiled in the right wantarray context
1888 (they were accidentally using the context of the sort() itself).
1889 The comparison block is now run in scalar context, and the arguments
1890 to be sorted are always provided list context.
1894 Changed the POSIX character class C<[[:space:]]> to include the (very
1895 rarely used) vertical tab character. Added a new POSIX-ish character
1896 class C<[[:blank:]]> which stands for horizontal whitespace
1897 (currently, the space and the tab).
1901 The tainting behaviour of sprintf() has been rationalized. It does
1902 not taint the result of floating point formats anymore, making the
1903 behaviour consistent with that of string interpolation.
1907 Some cases of inconsistent taint propagation (such as within hash
1908 values) have been fixed.
1912 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1913 of simple pattern matches. These are now handled better.
1917 Regular expression debug output (whether through C<use re 'debug'>
1918 or via C<-Dr>) now looks better.
1922 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
1927 Use of $& could trigger a core dump under some situations. This
1932 The regular expression captured submatches ($1, $2, ...) are now
1933 more consistently unset if the match fails, instead of leaving false
1934 data lying around in them.
1938 readline() on files opened in "slurp" mode could return an extra "" at
1939 the end in certain situations. This has been corrected.
1943 Autovivification of symbolic references of special variables described
1944 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
1949 Sys::Syslog ignored the C<LOG_AUTH> constant.
1953 All but the first argument of the IO syswrite() method are now optional.
1957 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1958 in multiple threads simultaneously are now thread-safe.
1962 Tie::ARRAY SPLICE method was broken.
1966 Allow read-only string on left hand side of non-modifying tr///.
1970 Several Unicode fixes.
1976 BOMs (byte order marks) in the beginning of Perl files
1977 (scripts, modules) should now be transparently skipped.
1978 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1982 The character tables have been updated to Unicode 3.1.1.
1986 Comparing with utf8 data does not magically upgrade non-utf8 data
1987 into utf8. (This was a problem for example if you were mixing data
1988 from I/O and Unicode data: your output might have got magically encoded
1993 Generating illegal Unicode code points like U+FFFE, or the UTF-16
1994 surrogates, now also generates an optional warning.
1998 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2002 Concatenation with the C<.> operator or via variable interpolation,
2003 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2004 substitution with C<s///>, single-quoted UTF8, should now work.
2008 The C<tr///> operator now works. Note that the C<tr///CU>
2009 functionality has been removed (but see pack('U0', ...)).
2013 C<eval "v200"> now works.
2017 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2018 This has been corrected.
2022 Zero entries were missing from the Unicode classes like C<IsDigit>.
2028 Large unsigned numbers (those above 2**31) could sometimes lose their
2029 unsignedness, causing bogus results in arithmetic operations.
2033 =head2 Platform Specific Changes and Fixes
2041 Perl now works on post-4.0 BSD/OSes.
2047 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2053 Numerous updates; currently synchronised with Cygwin 1.1.4.
2057 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2063 EPOC update after Perl 5.6.0. See README.epoc.
2069 Perl now works on post-3.0 FreeBSDs.
2075 README.hpux updated; C<Configure -Duse64bitall> now almost works.
2081 Numerous compilation flag and hint enhancements; accidental mixing
2082 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2092 Long doubles should now work (see INSTALL).
2096 Linux previously had problems related to sockaddrlen when using
2097 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
2105 Compilation of the standard Perl distribution in MacOS Classic should
2106 now work if you have the Metrowerks development environment and
2107 the missing Mac-specific toolkit bits. Contact the macperl mailing
2114 MPE/iX update after Perl 5.6.0. See README.mpeix.
2120 Perl now works on NetBSD/sparc.
2126 Now works with usethreads (see INSTALL).
2132 64-bitness using the Sun Workshop compiler now works.
2136 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2138 The operating system version letter now recorded in $Config{osvers}.
2139 Allow compiling with gcc (previously explicitly forbidden). Compiling
2140 with gcc still not recommended because buggy code results, even with
2147 Fixed various alignment problems that lead into core dumps either
2148 during build or later; no longer dies on math errors at runtime;
2149 now using full quad integers (64 bits), previously was using
2150 only 46 bit integers for speed.
2156 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2157 (see INSTALL); now works with Perl's malloc.
2159 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2160 unimplemented. It now works as documented.
2162 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2163 was that a pid of -1 would cause a wildcard search of all processes on
2164 the system. The most significant enhancement is that we can now
2165 usually get the completion status of a terminated process.
2167 POSIX-style signals are now emulated much better on VMS versions prior
2170 The C<system> function and backticks operator have improved
2171 functionality and better error handling.
2181 accept() no longer leaks memory.
2185 Borland C++ v5.5 is now a supported compiler that can build Perl.
2186 However, the generated binaries continue to be incompatible with those
2187 generated by the other supported compilers (GCC and Visual C++).
2191 Better chdir() return value for a non-existent directory.
2195 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2199 New %ENV entries now propagate to subprocesses.
2203 Current directory entries in %ENV are now correctly propagated to child
2208 $ENV{LIB} now used to search for libs under Visual C.
2212 fork() emulation has been improved in various ways, but still continues
2213 to be experimental. See L<perlfork> for known bugs and caveats.
2217 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2221 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2222 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2226 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2230 The makefiles now provide a single switch to bulk-enable all the features
2231 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2235 Allow REG_EXPAND_SZ keys in the registry.
2239 Can now send() from all threads, not just the first one.
2243 Fake signal handling reenabled, bugs and all.
2247 %SIG has been enabled under USE_ITHREADS, but its use is completely
2248 unsupported under all configurations.
2252 Less stack reserved per thread so that more threads can run
2253 concurrently. (Still 16M per thread.)
2257 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
2258 (works better when perl is running as service).
2262 Better UNC path handling under ithreads.
2266 wait(), waitpid() and backticks now return the correct exit status under
2271 winsock handle leak fixed.
2277 =head1 New or Changed Diagnostics
2283 The lexical warnings category "deprecated" is no longer a sub-category
2284 of the "syntax" category. It is now a top-level category in its own
2289 All regular expression compilation error messages are now hopefully
2290 easier to understand both because the error message now comes before
2291 the failed regex and because the point of failure is now clearly
2292 marked by a C<E<lt>-- HERE> marker.
2296 The various "opened only for", "on closed", "never opened" warnings
2297 drop the C<main::> prefix for filehandles in the C<main> package,
2298 for example C<STDIN> instead of C<main::STDIN>.
2302 The "Unrecognized escape" warning has been extended to include C<\8>,
2303 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2307 Two new debugging options have been added: if you have compiled your
2308 Perl with debugging, you can use the -DT and -DR options to trace
2309 tokenising and to add reference counts to displaying variables,
2314 perl5db.pl has been modified to present a more consistent commands
2315 interface, via (CommandSet=580). perl5db.t was also added to test the
2316 changes, and as a placeholder for further tests.
2322 If an attempt to use a (non-blessed) reference as an array index
2323 is made, a warning is given.
2327 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2328 now give a warning. This may be a problem for generated and evaled
2333 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2334 using the C<"C"> format you will get an optional warning. Similarly
2335 for the C<"c"> format and a number less than -128 or more than 127.
2339 Certain regex modifiers such as C<(?o)> make sense only if applied to
2340 the entire regex. You will an optional warning if you try to do otherwise.
2344 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2345 has been deprecated for a while. Now you will get an optional warning.
2349 =head1 Changed Internals
2355 perlapi.pod (a companion to perlguts) now attempts to document the
2360 You can now build a really minimal perl called microperl.
2361 Building microperl does not require even running Configure;
2362 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2363 many assumptions, some of which may be too bold; the resulting
2364 executable may crash or otherwise misbehave in wondrous ways.
2365 For careful hackers only.
2369 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2370 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2371 interfaces to the publicised API. For the full list of the available
2372 APIs see L<perlapi>.
2376 Made possible to propagate customised exceptions via croak()ing.
2380 Now xsubs can have attributes just like subs. (Well, at least the
2381 built-in attributes.)
2385 dTHR and djSP have been obsoleted; the former removed (because it's
2386 a no-op) and the latter replaced with dSP.
2390 PERL_OBJECT has been completely removed.
2394 The MAGIC constants (e.g. C<'P'>) have been macrofied
2395 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2396 and maintainability.
2400 The regex compiler now maintains a structure that identifies nodes in
2401 the compiled bytecode with the corresponding syntactic features of the
2402 original regex expression. The information is attached to the new
2403 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2404 complete information.
2408 The C code has been made much more C<gcc -Wall> clean. Some warning
2409 messages still remain in some platforms, so if you are compiling with
2410 gcc you may see some warnings about dubious practices. The warnings
2411 are being worked on.
2415 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2419 Documentation on how to use the Perl source repository has been added
2420 to F<Porting/repository.pod>.
2424 There are now several profiling make targets.
2428 =head1 Security Vulnerability Closed
2430 (This change was already made in 5.7.0 but bears repeating here.)
2432 A potential security vulnerability in the optional suidperl component
2433 of Perl was identified in August 2000. suidperl is neither built nor
2434 installed by default. As of November 2001 the only known vulnerable
2435 platform is Linux, most likely all Linux distributions. CERT and
2436 various vendors and distributors have been alerted about the vulnerability.
2437 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2438 for more information.
2440 The problem was caused by Perl trying to report a suspected security
2441 exploit attempt using an external program, /bin/mail. On Linux
2442 platforms the /bin/mail program had an undocumented feature which
2443 when combined with suidperl gave access to a root shell, resulting in
2444 a serious compromise instead of reporting the exploit attempt. If you
2445 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2446 suidperl is not installed, you are safe.
2448 The exploit attempt reporting feature has been completely removed from
2449 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2450 from all the Perl 5.7 releases), so that particular vulnerability
2451 isn't there anymore. However, further security vulnerabilities are,
2452 unfortunately, always possible. The suidperl functionality is most
2453 probably going to be removed in Perl 5.10. In any case, suidperl
2454 should only be used by security experts who know exactly what they are
2455 doing and why they are using suidperl instead of some other solution
2456 such as sudo (see http://www.courtesan.com/sudo/).
2460 Several new tests have been added, especially for the F<lib>
2461 subsection. There are now about 34 000 individual tests (spread over
2462 about 530 test scripts), in the regression suite (5.6.1 has about
2463 11700 tests, in 258 test scripts) Many of the new tests are introduced
2464 by the new modules, but still in general Perl is now more thoroughly
2467 Because of the large number of tests, running the regression suite
2468 will take considerably longer time than it used to: expect the suite
2469 to take up to 4-5 times longer to run than in perl 5.6. In a really
2470 fast machine you can hope to finish the suite in about 5 minutes
2473 The tests are now reported in a different order than in earlier Perls.
2474 (This happens because the test scripts from under t/lib have been moved
2475 to be closer to the library/extension they are testing.)
2477 =head1 Known Problems
2485 In AIX 4.2 Perl extensions that use C++ functions that use statics
2486 may have problems in that the statics are not getting initialized.
2487 In newer AIX releases this has been solved by linking Perl with
2488 the libC_r library, but unfortunately in AIX 4.2 the said library
2489 has an obscure bug where the various functions related to time
2490 (such as time() and gettimeofday()) return broken values, and
2491 therefore in AIX 4.2 Perl is not linked against the libC_r.
2495 vac 5.0.0.0 May Produce Buggy Code For Perl
2497 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2498 resulting in few random tests failing, but when the failing tests
2499 are run by hand, they succeed. We suggest upgrading to at least
2500 vac version 5.0.1.0, that has been known to compile Perl correctly.
2501 "lslpp -L|grep vac.C" will tell you the vac version.
2505 =head2 Amiga Perl Invoking Mystery
2507 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2508 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2509 known but the current suspect is the F<ixemul> library.
2511 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2513 Don't panic. Read INSTALL 'make test' section instead.
2515 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2517 The subtests 11 and 12 sometimes fail and sometimes work.
2519 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2521 The lib/io_multihomed test may hang in HP-UX if Perl has been
2522 configured to be 64-bit. Because other 64-bit platforms do not hang in
2523 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2524 test attempts to create and connect to "multihomed" sockets (sockets
2525 which have multiple IP addresses).
2527 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2529 If perl is configured with -Duse64bitall, the successful result of the
2530 subtest 10 of lib/posix may arrive before the successful result of the
2531 subtest 9, which confuses the test harness so much that it thinks the
2534 =head2 Linux With Sfio Fails op/misc Test 48
2540 The following tests are known to fail:
2542 Failed Test Stat Wstat Total Fail Failed List of Failed
2543 -------------------------------------------------------------------------
2544 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2545 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2546 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2547 ../lib/warnings.t 450 1 0.22% 316
2551 OS/390 has rather many test failures but the situation is actually
2552 better than it was in 5.6.0, it's just that so many new modules and
2553 tests have been added.
2555 Failed Test Stat Wstat Total Fail Failed List of Failed
2556 -----------------------------------------------------------------------------
2557 ../ext/B/Deparse.t 14 1 7.14% 14
2558 ../ext/B/Showlex.t 1 1 100.00% 1
2559 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2561 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2562 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2563 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2564 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2565 ../lib/warnings.t 434 1 0.23% 75
2566 ../lib/ExtUtils.t 27 1 3.70% 25
2567 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2568 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2569 ../lib/User/pwent.t 9 1 11.11% 4
2570 op/pat.t 660 6 0.91% 242-243 424-425
2572 op/split.t 0 9 ?? ?? % ??
2573 op/taint.t 174 3 1.72% 156 162 168
2574 op/tr.t 70 3 4.29% 50 58-59
2575 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2577 =head2 op/sprintf tests 129 and 130
2579 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2580 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2581 The failing platforms do not comply with the ANSI C Standard, line
2582 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2583 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2584 the printf format "%.0f", most often they produce "0" and "-0".)
2586 =head2 Failure of Thread tests
2588 B<Note that support for 5.005-style threading remains experimental
2589 and practically unsupported.>
2591 The following tests are known to fail due to fundamental problems in
2592 the 5.005 threading implementation. These are not new failures--Perl
2593 5.005_0x has the same bugs, but didn't have these tests.
2595 ext/List/Util/t/first 2
2597 ext/Thread/thr5005 19-20
2599 These failures are unlikely to get fixed.
2607 ext/POSIX/sigaction subtests 6 and 13 may fail.
2611 lib/ExtUtils may spuriously claim that subtest 28 failed,
2612 which is interesting since the test only has 27 tests.
2616 Numerous numerical test failures
2618 op/numconvert 209,210,217,218
2620 ext/Time/HiRes/HiRes 9
2621 lib/Math/BigInt/t/bigintpm 1145
2624 These tests fail because of yet unresolved floating point inaccuracies.
2628 =head2 UNICOS and UNICOS/mk
2630 The io/fs test #31 is failing because in UNICOS and UNICOS/mk
2631 truncate() cannot be used to grow the size of filehandles, only
2632 to reduce the size. The workaround is to truncate files instead
2637 There are a few known test failures, see L<perluts>.
2641 There is one known test failure with a default configuration:
2643 [.run]switches..........................FAILED on test 1
2647 In multi-CPU boxes there are some problems with the I/O buffering:
2648 some output may appear twice.
2650 =head2 Localising a Tied Variable Leaks Memory
2653 tie my %tie_hash => 'Tie::StdHash';
2657 local($tie_hash{Foo}) = 1; # leaks
2659 Code like the above is known to leak memory every time the local()
2662 =head2 Localising Tied Arrays and Hashes Is Broken
2666 doesn't work as one would expect: the old value is restored
2669 =head2 Self-tying of Arrays and Hashes Is Forbidden
2671 Self-tying of arrays and hashes is broken in rather deep and
2672 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2673 frustrated at the mysterious results (core dumps, most often) it is
2674 for now forbidden (you will get a fatal error even from an attempt).
2676 =head2 Building Extensions Can Fail Because Of Largefiles
2678 Some extensions like mod_perl are known to have issues with
2679 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2680 default to 64 bits wide, where supported. Modules may fail to compile
2681 at all or compile and work incorrectly. Currently there is no good
2682 solution for the problem, but Configure now provides appropriate
2683 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2684 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2685 having problems can try configuring themselves without the
2686 largefileness. This is admittedly not a clean solution, and the
2687 solution may not even work at all. One potential failure is whether
2688 one can (or, if one can, whether it's a good idea) link together at
2689 all binaries with different ideas about file offsets, all this is
2692 =head2 Unicode Support on EBCDIC Still Spotty
2694 Though mostly working, Unicode support still has problem spots on
2695 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2696 regular expression constructs for code points less than 256: the
2697 pP are testing for Unicode code points, not knowing about EBCDIC.
2699 =head2 The Compiler Suite Is Still Experimental
2701 The compiler suite is slowly getting better but it continues to be
2702 highly experimental. Use in production environments is discouraged.
2704 =head2 The Long Double Support Is Still Experimental
2706 The ability to configure Perl's numbers to use "long doubles",
2707 floating point numbers of hopefully better accuracy, is still
2708 experimental. The implementations of long doubles are not yet
2709 widespread and the existing implementations are not quite mature
2710 or standardised, therefore trying to support them is a rare
2711 and moving target. The gain of more precision may also be offset
2712 by slowdown in computations (more bits to move around, and the
2713 operations are more likely to be executed by less optimised
2716 =head2 Seen In Perl 5.7 But Gone Now
2718 C<Time::Piece> (previously known as C<Time::Object>) was removed
2719 because it was felt that it didn't have enough value in it to be a
2720 core module. It is still a useful module, though, and is available
2723 =head1 Reporting Bugs
2725 If you find what you think is a bug, you might check the articles
2726 recently posted to the comp.lang.perl.misc newsgroup and the perl
2727 bug database at http://bugs.perl.org. There may also be
2728 information at http://www.perl.com/, the Perl Home Page.
2730 If you believe you have an unreported bug, please run the B<perlbug>
2731 program included with your release. Be sure to trim your bug down
2732 to a tiny but sufficient test case. Your bug report, along with the
2733 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2734 analysed by the Perl porting team.
2738 The F<Changes> file for exhaustive details on what changed.
2740 The F<INSTALL> file for how to build Perl.
2742 The F<README> file for general stuff.
2744 The F<Artistic> and F<Copying> files for copyright information.
2748 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.