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 REF(...) Instead Of SCALAR(...)
119 A reference to a reference now stringifies as "REF(0x81485ec)" instead
120 of "SCALAR(0x81485ec)" in order to be more consistent with the return
123 =head2 pack/unpack D/F recycled
125 The undocumented pack/unpack template letters D/F have been recycled
126 for better use: now they stand for long double (if supported by the
127 platform) and NV (Perl internal floating point type). (They used
128 to be aliases for d/f, but you never knew that.)
136 The semantics of bless(REF, REF) were unclear and until someone proves
137 it to make some sense, it is forbidden.
141 The obsolete chat2 library that should never have been allowed
142 to escape the laboratory has been decommissioned.
146 The builtin dump() function has probably outlived most of its
147 usefulness. The core-dumping functionality will remain in future
148 available as an explicit call to C<CORE::dump()>, but in future
149 releases the behaviour of an unqualified C<dump()> call may change.
153 The very dusty examples in the eg/ directory have been removed.
154 Suggestions for new shiny examples welcome but the main issue is that
155 the examples need to be documented, tested and (most importantly)
160 The (bogus) escape sequences \8 and \9 now give an optional warning
161 ("Unrecognized escape passed through"). There is no need to \-escape
166 The list of filenames from glob() (or <...>) is now by default sorted
167 alphabetically to be csh-compliant (which is what happened before
168 in most UNIX platforms). (bsd_glob() does still sort platform
169 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
173 Spurious syntax errors generated in certain situations, when glob()
174 caused File::Glob to be loaded for the first time, have been fixed.
178 Although "you shouldn't do that", it was possible to write code that
179 depends on Perl's hashed key order (Data::Dumper does this). The new
180 algorithm "One-at-a-Time" produces a different hashed key order.
181 More details are in L</"Performance Enhancements">.
185 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
186 In future releases this may become a fatal error.
190 The C<package;> syntax (C<package> without an argument) has been
191 deprecated. Its semantics were never that clear and its
192 implementation even less so. If you have used that feature to
193 disallow all but fully qualified variables, C<use strict;> instead.
197 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
198 recognised but now cause fatal errors. The previous behaviour of
199 ignoring them by default and warning if requested was unacceptable
200 since it, in a way, falsely promised that the features could be used.
204 The current user-visible implementation of pseudo-hashes (the weird
205 use of the first array element) is deprecated starting from Perl 5.8.0
206 and will be removed in Perl 5.10.0, and the feature will be
207 implemented differently. Not only is the current interface rather
208 ugly, but the current implementation slows down normal array and hash
209 use quite noticeably. The C<fields> pragma interface will remain
210 available. The I<restricted hashes> interface is expected to
211 be the replacement interface (see L<Hash::Util>).
215 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
219 After years of trying the suidperl is considered to be too complex to
220 ever be considered truly secure. The suidperl functionality is likely
221 to be removed in a future release.
225 The long deprecated uppercase aliases for the string comparison
226 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
230 The tr///C and tr///U features have been removed and will not return;
231 the interface was a mistake. Sorry about that. For similar
232 functionality, see pack('U0', ...) and pack('C0', ...).
236 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
237 The prototypes are now checked at compile-time for invalid characters.
238 An optional warning is generated ("Illegal character in prototype...")
239 but this may be upgraded to a fatal error in a future release.
243 =head1 Core Enhancements
245 =head2 PerlIO is Now The Default
251 IO is now by default done via PerlIO rather than system's "stdio".
252 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
253 handle's behaviour. Layers can be specified at open time via 3-arg
256 open($fh,'>:crlf :utf8', $path) || ...
258 or on already opened handles via extended C<binmode>:
260 binmode($fh,':encoding(iso-8859-7)');
262 The built-in layers are: unix (low level read/write), stdio (as in
263 previous Perls), perlio (re-implementation of stdio buffering in a
264 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
265 but available on any platform). A mmap layer may be available if
266 platform supports it (mostly UNIXes).
268 Layers to be applied by default may be specified via the 'open' pragma.
270 See L</"Installation and Configuration Improvements"> for the effects
271 of PerlIO on your architecture name.
275 File handles can be marked as accepting Perl's internal encoding of Unicode
276 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
278 open($fh,">:utf8","Uni.txt");
280 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
281 for you since it's not UTF-8 what you will be getting but instead
282 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
283 http://www.unicode.org/unicode/reports/tr16/ for more information.
284 In future releases this naming may change.
288 File handles can translate character encodings from/to Perl's internal
289 Unicode form on read/write via the ":encoding()" layer.
293 File handles can be opened to "in memory" files held in Perl scalars via:
295 open($fh,'>', \$variable) || ...
299 Anonymous temporary files are available without need to
300 'use FileHandle' or other module via
302 open($fh,"+>", undef) || ...
304 That is a literal undef, not an undefined value.
308 The list form of C<open> is now implemented for pipes (at least on UNIX):
310 open($fh,"-|", 'cat', '/etc/motd')
312 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
317 If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG)
318 contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
319 the default encoding of your STDIN, STDOUT, and STDERR, and of
320 B<any subsequent file open>, is UTF-8.
326 Perl used to be fragile in that signals arriving at inopportune moments
327 could corrupt Perl's internal state. Now Perl postpones handling of
328 signals until it's safe (between opcodes).
330 This change may have surprising side effects because signals no longer
331 interrupt Perl instantly. Perl will now first finish whatever it was
332 doing, like finishing an internal operation (like sort()) or an
333 external operation (like an I/O operation), and only then look at any
334 arrived signals (and before starting the next operation). No more corrupt
335 internal state since the current operation is always finished first,
336 but the signal may take more time to get heard. Note that breaking
337 out from potentially blocking operations should still work, though.
339 =head2 Unicode Overhaul
341 Unicode in general should be now much more usable than in Perl 5.6.0
342 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
343 regular expressions should work now, Unicode in tr/// should work now,
344 Unicode in I/O should work now. See L<perluniintro> for introduction
345 and L<perlunicode> for details.
351 The Unicode Character Database coming with Perl has been upgraded
352 to Unicode 3.2.0. For more information, see http://www.unicode.org/ .
356 For developers interested in enhancing Perl's Unicode capabilities:
357 almost all the UCD files are included with the Perl distribution in
358 the F<lib/unicore subdirectory>. The most notable omission, for space
359 considerations, is the Unihan database.
363 The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
364 C isblank(), that is, it contains only "horizontal whitespace" (the space
365 character is, the newline isn't), and the "SpacePerl" is the Unicode
366 equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
367 tabulator character, whereas C<\s> doesn't.)
369 See "New Unicode Properties" earlier in this document for additional
370 information on changes with Unicode properties.
374 =head2 Understanding of Numbers
376 In general a lot of fixing has happened in the area of Perl's
377 understanding of numbers, both integer and floating point. Since in
378 many systems the standard number parsing functions like C<strtoul()>
379 and C<atof()> seem to have bugs, Perl tries to work around their
380 deficiencies. This results hopefully in more accurate numbers.
382 Perl now tries internally to use integer values in numeric conversions
383 and basic arithmetics (+ - * /) if the arguments are integers, and
384 tries also to keep the results stored internally as integers.
385 This change leads to often slightly faster and always less lossy
386 arithmetics. (Previously Perl always preferred floating point numbers
389 =head2 Miscellaneous Changes
395 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
396 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
400 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
401 in multiple arguments.)
405 The builtin dump() now gives an optional warning
406 C<dump() better written as CORE::dump()>,
407 meaning that by default C<dump(...)> is resolved as the builtin
408 dump() which dumps core and aborts, not as (possibly) user-defined
409 C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
410 (The whole dump() feature is to considered deprecated, and possibly
411 removed/changed in future releases.)
415 chomp() and chop() are now overridable. Note, however, that their
416 prototype (as given by C<prototype("CORE::chomp")> is undefined,
417 because it cannot be expressed and therefore one cannot really write
418 replacements to override these builtins.
422 END blocks are now run even if you exit/die in a BEGIN block.
423 Internally, the execution of END blocks is now controlled by
424 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
425 behaviour for Perl embedders. This will default in 5.10. See
430 Formats now support zero-padded decimal fields.
434 Lvalue subroutines can now return C<undef> in list context.
435 However, the lvalue subroutine feature still remains experimental.
439 A lost warning "Can't declare ... dereference in my" has been
440 restored (Perl had it earlier but it became lost in later releases.)
444 A new special regular expression variable has been introduced:
445 C<$^N>, which contains the most-recently closed group (submatch).
449 C<no Module;> now works even if there is no "sub unimport" in the Module.
453 The numerical comparison operators return C<undef> if either operand
454 is a NaN. Previously the behaviour was unspecified.
458 The following builtin functions are now overridable: each(), keys(),
459 pop(), push(), shift(), splice(), unshift().
463 C<pack() / unpack()> now can group template letters with C<()> and then
464 apply repetition/count modifiers on the groups.
468 C<pack() / unpack()> can now process the Perl internal numeric types:
469 IVs, UVs, NVs-- and also long doubles, if supported by the platform.
470 The template letters are C<j>, C<J>, C<F>, and C<D>.
474 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
478 my __PACKAGE__ $obj now works.
482 The printf() and sprintf() now support parameter reordering using the
483 C<%\d+\$> and C<*\d+\$> syntaxes. For example
485 print "%2\$s %1\$s\n", "foo", "bar";
487 will print "bar foo\n". This feature helps in writing
488 internationalised software, and in general when the order
489 of the parameters can vary.
493 prototype(\&) is now available.
497 prototype(\[$@%&]) is now available to implicitly create references
498 (useful for example if you want to emulate the tie() interface).
502 A new command-line option, C<-t> is available. It is the
503 little brother of C<-T>: instead of dieing on taint violations,
504 lexical warnings are given. B<This is only meant as a temporary
505 debugging aid while securing the code of old legacy applications.
506 This is not a substitute for -T.>
510 In other taint news, the C<exec LIST> and C<system LIST> have now been
511 considered too risky (think C<exec @ARGV>: it can start any program
512 with any arguments), and now the said forms cause a warning.
513 You should carefully launder the arguments to guarantee their
514 validity. In future releases of Perl the forms will become fatal
515 errors so consider starting laundering now.
519 If tr/// is just counting characters, it doesn't attempt to
524 untie() will now call an UNTIE() hook if it exists. See L<perltie>
529 L<utime> now supports C<utime undef, undef, @files> to change the
530 file timestamps to the current time.
534 The rules for allowing underscores (underbars) in numeric constants
535 have been relaxed and simplified: now you can have an underscore
536 simply B<between digits>.
540 Rather than relying on C's argv[0] (which may not contain a full pathname)
541 where possible $^X is now set by asking the operating system.
542 (eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD)
546 A new variable, C<${^TAINT}>, indicates whether taint mode is enabled.
550 You can now override the readline() builtin, and this overrides also
551 the <FILEHANDLE> angle bracket operator.
555 The command-line options -s and -F are now recognized on the shebang
560 Use of the C</c> match modifier without an accompanying C</g> modifier
561 elicits a new warning: C<Use of /c modifier is meaningless without /g>.
562 Use of C</c> in substitutions, even with C</g>, elicits
563 C<Use of /c modifier is meaningless in s///>.
567 =head1 Modules and Pragmata
569 =head2 New Modules and Pragmata
575 C<Attribute::Handlers> allows a class to define attribute handlers.
578 use Attribute::Handlers;
579 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
581 # later, in some package using or inheriting from MyPack...
583 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
585 Both variables and routines can have attribute handlers. Handlers can
586 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
587 exact compilation phase (BEGIN, CHECK, INIT, or END).
591 B<B::Concise> is a new compiler backend for walking the Perl syntax
592 tree, printing concise info about ops, from Stephen McCamant. The
593 output is highly customisable. See L<B::Concise>.
597 The new bignum, bigint, and bigrat pragmas implement transparent
598 bignum support (using the Math::BigInt, Math::BigFloat, and
599 Math::BigRat backends), by Tels.
603 C<Class::ISA> for reporting the search path for a class's ISA tree,
604 by Sean Burke, has been added. See L<Class::ISA>.
608 C<Cwd> has now a split personality: if possible, an XS extension is
609 used, (this will hopefully be faster, more secure, and more robust)
610 but if not possible, the familiar Perl implementation is used.
614 C<Devel::PPPort>, originally from Kenneth Albanowski and now
615 maintained by Paul Marquess, has been added. It is primarily used
616 by C<h2xs> to enhance portability of XS modules between different
621 C<Digest>, frontend module for calculating digests (checksums), from
622 Gisle Aas, has been added. See L<Digest>.
626 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
627 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
629 use Digest::MD5 'md5_hex';
631 $digest = md5_hex("Thirsty Camel");
633 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
635 NOTE: the C<MD5> backward compatibility module is deliberately not
636 included since its further use is discouraged.
640 C<Encode>, by Nick Ing-Simmons and Dan Kogai, provides a mechanism to
641 translate between different character encodings. Support for Unicode,
642 ISO-8859-1, and ASCII are compiled in to the module. Several other
643 encodings (like the rest of the ISO-8859, CP*/Win*, Mac, KOI8-R, three
644 variants EBCDIC, Chinese, Japanese, and Korean encodings) are included
645 and can be loaded at runtime. (For space considerations, the largest
646 Chinese encodings have been separated into their own CPAN module,
647 Encode::HanExtra, which Encode will use if available). See L<Encode>.
649 Any encoding supported by Encode module is also available to the
650 ":encoding()" layer if PerlIO is used.
654 C<Hash::Util> is the interface to the new I<restricted hashes>
655 feature. A restricted hash is restricted to a certain set of keys,
656 no keys outside the set can be added. Also individual keys can be
657 restricted so that the key cannot be deleted and the value cannot be
658 changed. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and
663 C<I18N::Langinfo> can be use to query locale information.
664 See L<I18N::Langinfo>.
668 C<I18N::LangTags> has functions for dealing with RFC3066-style
669 language tags, by Sean Burke. See L<I18N::LangTags>.
673 C<ExtUtils::Constant> is a new tool for extension writers for
674 generating XS code to import C header constants, by Nicholas Clark.
675 See L<ExtUtils::Constant>.
679 C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
680 from Damian Conway. See L<Filter::Simple>.
686 use Filter::Simple sub {
687 while (my ($from, $to) = splice @_, 0, 2) {
696 use MyFilter qr/red/ => 'green';
698 print "red\n"; # this code is filtered, will print "green\n"
699 print "bored\n"; # this code is filtered, will print "bogreen\n"
703 print "red\n"; # this code is not filtered, will print "red\n"
707 C<File::Temp> allows one to create temporary files and directories in
708 an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
712 C<Filter::Util::Call> provides you with the framework to write
713 I<Source Filters> in Perl, from Paul Marquess. For most uses the
714 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
718 C<if> is a new pragma for conditional inclusion of modules, from
723 L<libnet> is a collection of perl5 modules related to network
724 programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
725 L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
727 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
731 C<List::Util> is a selection of general-utility list subroutines, like
732 sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
736 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
737 C<Locale::Language>, from Neil Bowers, have been added. They provide the
738 codes for various locale standards, such as "fr" for France, "usd" for
739 US Dollar, and "jp" for Japanese.
743 $country = code2country('jp'); # $country gets 'Japan'
744 $code = country2code('Norway'); # $code gets 'no'
746 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
747 and L<Locale::Language>.
751 C<Locale::Maketext> is localization framework from Sean Burke. See
752 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
753 article about software localization, originally published in The Perl
754 Journal #13, republished here with kind permission.
758 Math::BigRat for big rational numbers, to accompany Math::BigInt and
759 Math::BigFloat, from Tels.
763 C<Memoize> can make your functions faster by trading space for time,
764 from Mark-Jason Dominus. See L<Memoize>.
768 C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
769 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
774 $encoded = encode_base64('Aladdin:open sesame');
775 $decoded = decode_base64($encoded);
777 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
783 C<MIME::QuotedPrint> allows you to encode data in quoted-printable
784 encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
785 Extensions)>, from Gisle Aas.
787 use MIME::QuotedPrint;
789 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
790 $decoded = decode_qp($encoded);
792 print $encoded, "\n"; # "Smiley in Unicode: =263A"
794 MIME::QuotedPrint has been enhanced to provide the basic methods
795 necessary to use it with PerlIO::Via as in :
797 use MIME::QuotedPrint;
798 open($fh,">Via(MIME::QuotedPrint)",$path);
800 See L<MIME::QuotedPrint>.
804 C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
809 C<open> is a new pragma for setting the default I/O disciplines
814 C<PerlIO::Scalar> provides the implementation of IO to "in memory"
815 Perl scalars as discussed above, from Nick Ing-Simmons. It also
816 serves as an example of a loadable PerlIO layer. Other future
817 possibilities include PerlIO::Array and PerlIO::Code.
818 See L<PerlIO::Scalar>.
822 C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
823 functionality provided by a class (typically implemented in perl
824 code), from Nick Ing-Simmons.
826 use MIME::QuotedPrint;
827 open($fh,">Via(MIME::QuotedPrint)",$path);
829 This will automatically convert everything output to C<$fh>
830 to Quoted-Printable. See L<PerlIO::Via>.
834 C<Pod::ParseLink>, by Russ Allbery, has been added,
835 to parse LZ<><> links in pods as described in the new
840 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
841 It converts POD data to formatted overstrike text.
842 See L<Pod::Text::Overstrike>.
846 C<Scalar::Util> is a selection of general-utility scalar subroutines,
847 like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
851 C<sort> is a new pragma for controlling the behaviour of sort().
855 C<Storable> gives persistence to Perl data structures by allowing the
856 storage and retrieval of Perl data to and from files in a fast and
857 compact binary format, from Raphael Manfredi. See L<Storable>.
861 C<Switch>, from Damian Conway, has been added. Just by saying
865 you have C<switch> and C<case> available in Perl.
871 case 1 { print "number 1" }
872 case "a" { print "string a" }
873 case [1..10,42] { print "number in list" }
874 case (@array) { print "number in list" }
875 case /\w+/ { print "pattern" }
876 case qr/\w+/ { print "pattern" }
877 case (%hash) { print "entry in hash" }
878 case (\%hash) { print "entry in hash" }
879 case (\&sub) { print "arg to subroutine" }
880 else { print "previous case not true" }
887 C<Test::More> is yet another framework for writing test scripts,
888 more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
892 C<Test::Simple> has basic utilities for writing tests, by Michael
893 Schwern. See L<Test::Simple>.
897 C<Text::Balanced> has been added, for extracting delimited text
898 sequences from strings, from Damian Conway.
900 use Text::Balanced 'extract_delimited';
902 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
904 $a will be "'never say never'", $b will be ', he never said'.
906 In addition to extract_delimited() there are also extract_bracketed(),
907 extract_quotelike(), extract_codeblock(), extract_variable(),
908 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
909 gen_extract_tagged(). With these you can implement rather advanced
910 parsing algorithms. See L<Text::Balanced>.
914 C<threads> is an interface to interpreter threads, by Arthur Bergman.
915 Interpreter threads (ithreads) is the new thread model introduced in
916 Perl 5.6 but only available as an internal interface for extension
917 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
921 C<threads::shared> allows data sharing for interpreter threads, from
922 Arthur Bergman. In the ithreads model any data sharing between
923 threads must be explicit, as opposed to the old 5.005 thread model
924 where data sharing was implicit. See L<threads::shared>.
928 C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
933 C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
937 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
938 references (unlike the standard Tie::RefHash) The module is contained
939 within Tie::RefHash, see L<Tie::RefHash>.
943 C<Time::HiRes> provides high resolution timing (ualarm, usleep,
944 and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
948 C<Unicode::UCD> offers a querying interface to the Unicode Character
949 Database. See L<Unicode::UCD>.
953 C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
954 for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
958 C<Unicode::Normalize> implements the various Unicode normalization
959 forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
963 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
964 typemaps. Nothing gets installed but for extension writers the code
969 =head2 Updated And Improved Modules and Pragmata
975 The following independently supported modules have been updated to the
976 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
977 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
978 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
979 Term::ANSIColor, Test, Text-Tabs+Wrap.
983 The attributes::reftype() now works on tied arguments.
987 AutoLoader can now be disabled with C<no AutoLoader;>.
991 B::Deparse has been significantly enhanced. It now can deparse almost
992 all of the standard test suite (so that the tests still succeed).
993 There is a make target "test.deparse" for trying this out.
997 Class::Struct can now define the classes in compile time.
1001 Class::Struct now assigns the array/hash element if the accessor
1002 is called with an array/hash element as the B<sole> argument.
1006 Data::Dumper has now an option to sort hashes.
1010 Data::Dumper has now an option to dump code references
1015 DB_File now supports newer Berkeley DB versions, among
1020 The English module can now be used without the infamous performance
1023 use English '-no_match_vars';
1025 (Assuming, of course, that one doesn't need the troublesome variables
1026 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1027 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1031 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
1032 new-style constant dispatch section (see L<ExtUtils::Constant>).
1033 This means that they will be more robust and hopefully faster.
1037 File::Find now chdir()s correctly when chasing symbolic links.
1041 File::Find now has pre- and post-processing callbacks. It also
1042 correctly changes directories when chasing symbolic links. Callbacks
1043 (naughtily) exiting with "next;" instead of "return;" now work.
1047 File::Find is now (again) reentrant. It also has been made
1052 The warnings issued by File::Find now belong to their own category.
1053 You can enable/disable them with C<use/no warnings 'File::Find';>.
1057 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1058 prototype mismatch with CORE::glob().
1062 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1063 the returned list of filenames.
1067 Devel::Peek now has an interface for the Perl memory statistics
1068 (this works only if you are using perl's malloc, and if you have
1069 compiled with debugging).
1073 IPC::Open3 now allows the use of numeric file descriptors.
1077 IO::Socket has now atmark() method, which returns true if the socket
1078 is positioned at the out-of-band mark. The method is also exportable
1079 as a sockatmark() function.
1083 IO::Socket::INET has support for ReusePort option (if your platform
1084 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
1085 you may want to prefer ReuseAddr.
1089 IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
1090 that the operating system will make one up.)
1094 use lib now works identically to @INC. Removing directories
1095 with 'no lib' now works.
1099 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1100 leads into better portability.
1104 Math::BigFloat and Math::BigInt have undergone a full rewrite.
1105 They are now magnitudes faster, and they support various
1106 bignum libraries such as GMP and PARI as their backends.
1110 Math::Complex handles inf, NaN etc., better.
1114 Net::Ping has been muchly enhanced. Multihoming is now supported.
1115 There is now "external" protocol which uses Net::Ping::External module
1116 which runs external ping(1) and parses the output. A version of
1117 Net::Ping::External is available in CPAN.
1121 POSIX::sigaction() is now much more flexible and robust.
1122 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1123 handlers, installing new handlers was not atomic.
1127 In Safe the C<%INC> now localised in a Safe compartment so that
1132 In SDBM_File on dosish platforms, some keys went missing because of
1133 lack of support for files with "holes". A workaround for the problem
1138 In Search::Dict one can now have a pre-processing hook for the
1139 lines being searched.
1143 The Shell module now has an OO interface.
1147 In Sys::Syslog there is now a failover mechanism that will go
1148 through alternative connection mechanisms until the message
1149 is successfully logged.
1153 The Test module has been significantly enhanced.
1157 Time::Local::timelocal() does not handle fractional seconds anymore.
1158 The rationale is that neither does localtime(), and timelocal() and
1159 localtime() are supposed to be inverses of each other.
1163 The vars pragma now supports declaring fully qualified variables.
1164 (Something that C<our()> does not and will not support.)
1168 The C<utf8::> name space (as in the pragma) provides various
1169 Perl-callable functions to provide low level access to Perl's
1170 internal Unicode representation. At the moment only length()
1171 has been implemented.
1175 =head1 Utility Changes
1181 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1186 F<emacs/e2ctags.pl> is now much faster.
1190 C<h2ph> now supports C trigraphs.
1194 C<h2xs> now produces a template README.
1198 C<h2xs> now uses C<Devel::PPort> for better portability between
1199 different versions of Perl.
1203 C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
1204 newly created extensions that define constants. Since the new code is
1205 more correct (if you have two constants where the first one is a
1206 prefix of the second one, the first constant B<never> gets defined),
1207 less lossy (it uses integers for integer constant, as opposed to the
1208 old code that used floating point numbers even for integer constants),
1209 and slightly faster, you might want to consider regenerating your
1210 extension code (the new scheme makes regenerating easy).
1211 L<h2xs> now also supports C trigraphs.
1215 C<libnetcfg> has been added to configure the libnet.
1219 C<perlbug> is now much more robust. It also sends the bug report to
1220 perl.org, not perl.com.
1224 C<perlcc> has been rewritten and its user interface (that is,
1225 command line) is much more like that of the UNIX C compiler, cc.
1226 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1230 C<perlivp> is a new Installation Verification Procedure utility
1231 for running any time after installing Perl.
1235 C<pod2html> now allows specifying a cache directory.
1239 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1240 implementation of sed in Perl: you can use the sed functionality by
1241 using the C<psed> utility.)
1245 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1249 C<xsubpp> now supports OUT keyword.
1253 =head1 New Documentation
1259 perl56delta details the changes between the 5.005 release and the
1264 perlclib documents the internal replacements for standard C library
1265 functions. (Interesting only for extension writers and Perl core
1270 perldebtut is a Perl debugging tutorial.
1274 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1278 perlintro is a gentle introduction to Perl.
1282 perliol documents the internals of PerlIO with layers.
1286 perlmodstyle is a style guide for writing modules.
1290 perlnewmod tells about writing and submitting a new module.
1294 perlpacktut is a pack() tutorial.
1298 perlpod has been rewritten to be clearer and to record the best
1299 practices gathered over the years.
1303 perlpodspec is a more formal specification of the pod format,
1304 mainly of interest for writers of pod applications, not to
1305 people writing in pod.
1309 perlretut is a regular expression tutorial.
1313 perlrequick is a regular expressions quick-start guide.
1314 Yes, much quicker than perlretut.
1318 perltodo has been updated.
1322 perltootc has been renamed as perltooc (to not to conflict
1323 with perltoot in filesystems restricted to "8.3" names)
1327 perluniintro is an introduction to using Unicode in Perl.
1328 (perlunicode is more of a detailed reference and background
1333 perlutil explains the command line utilities packaged with the Perl
1338 The following platform-specific documents are available before
1339 the installation as README.I<platform>, and after the installation
1342 perlaix perlamiga perlapollo perlbeos perlbs2000
1343 perlce perlcygwin perldgux perldos perlepoc perlhpux
1344 perlhurd perlmachten perlmacos perlmint perlmpeix
1345 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1346 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1352 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1353 confusion with the Perl POSIX module.
1357 The documentation for the WinCE platform is called perlce (README.ce
1358 in the source code kit), to avoid confusion with the perlwin32
1359 documentation on 8.3-restricted filesystems.
1363 =head1 Performance Enhancements
1369 map() could get pathologically slow when the result list it generates
1370 is larger than the source list. The performance has been improved for
1375 sort() has been changed to use primarily mergesort internally as
1376 opposed to the earlier quicksort. For very small lists this may
1377 result in slightly slower sorting times, but in general the speedup
1378 should be at least 20%. Additional bonuses are that the worst case
1379 behaviour of sort() is now better (in computer science terms it now
1380 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1381 worst-case run time behaviour), and that sort() is now stable
1382 (meaning that elements with identical keys will stay ordered as they
1383 were before the sort). See the C<sort> pragma for information.
1385 The story in more detail: suppose you want to serve yourself a little
1388 @digits = ( 3,1,4,1,5,9 );
1390 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1391 Which C<1> comes first is hard to know, since one C<1> looks pretty
1392 much like any other. You can regard this as totally trivial,
1393 or somewhat profound. However, if you just want to sort the even
1394 digits ahead of the odd ones, then what will
1396 sort { ($a % 2) <=> ($b % 2) } @digits;
1398 yield? The only even digit, C<4>, will come first. But how about
1399 the odd numbers, which all compare equal? With the quicksort algorithm
1400 used to implement Perl 5.6 and earlier, the order of ties is left up
1401 to the sort. So, as you add more and more digits of Pi, the order
1402 in which the sorted even and odd digits appear will change.
1403 and, for sufficiently large slices of Pi, the quicksort algorithm
1404 in Perl 5.8 won't return the same results even if reinvoked with the
1405 same input. The justification for this rests with quicksort's
1406 worst case behavior. If you run
1408 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1410 (something you might approximate if you wanted to merge two sorted
1411 arrays using sort), doubling $N doesn't just double the quicksort time,
1412 it I<quadruples> it. Quicksort has a worst case run time that can
1413 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1414 on patterns that may well arise in normal use. You won't notice this
1415 for small arrays, but you I<will> notice it with larger arrays,
1416 and you may not live long enough for the sort to complete on arrays
1417 of a million elements. So the 5.8 quicksort scrambles large arrays
1418 before sorting them, as a statistical defence against quadratic behaviour.
1419 But that means if you sort the same large array twice, ties may be
1420 broken in different ways.
1422 Because of the unpredictability of tie-breaking order, and the quadratic
1423 worst-case behaviour, quicksort was I<almost> replaced completely with
1424 a stable mergesort. I<Stable> means that ties are broken to preserve
1425 the original order of appearance in the input array. So
1427 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1429 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1430 appear in the output in the same order they appeared in the input.
1431 Mergesort has worst case O(NlogN) behaviour, the best value
1432 attainable. And, ironically, this mergesort does particularly
1433 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1434 in O(N) time. But quicksort was rescued at the last moment because
1435 it is faster than mergesort on certain inputs and platforms.
1436 For example, if you really I<don't> care about the order of even
1437 and odd digits, quicksort will run in O(N) time; it's very good
1438 at sorting many repetitions of a small number of distinct elements.
1439 The quicksort divide and conquer strategy works well on platforms
1440 with relatively small, very fast, caches. Eventually, the problem gets
1441 whittled down to one that fits in the cache, from which point it
1442 benefits from the increased memory speed.
1444 Quicksort was rescued by implementing a sort pragma to control aspects
1445 of the sort. The B<stable> subpragma forces stable behaviour,
1446 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1447 subpragmas are heavy-handed ways to select the underlying implementation.
1448 The leading C<_> is a reminder that these subpragmas may not survive
1449 beyond 5.8. More appropriate mechanisms for selecting the implementation
1450 exist, but they wouldn't have arrived in time to save quicksort.
1454 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1455 ( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is
1456 reasonably fast while producing a much better spread of values than
1457 the old hashing algorithm (originally by Chris Torek, later tweaked by
1458 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1459 all 3-char printable ASCII keys comes much closer to passing the
1460 DIEHARD random number generation tests. According to perlbench, this
1461 change has not affected the overall speed of Perl.
1465 unshift() should now be noticeably faster.
1469 =head1 Installation and Configuration Improvements
1471 =head2 Generic Improvements
1477 INSTALL now explains how you can configure Perl to use 64-bit
1478 integers even on non-64-bit platforms.
1482 Policy.sh policy change: if you are reusing a Policy.sh file
1483 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1484 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1485 them will now be changed to the new prefix, /foo/bar. (Previously
1486 only $prefix changed.) If you do not like this new behaviour,
1487 specify prefix, siteprefix, and vendorprefix explicitly.
1491 A new optional location for Perl libraries, otherlibdirs, is available.
1492 It can be used for example for vendor add-ons without disturbing Perl's
1493 own library directories.
1497 In many platforms the vendor-supplied 'cc' is too stripped-down to
1498 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1499 to be the case and 'cc' does not seem to be the GNU C compiler
1500 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1504 gcc needs to closely track the operating system release to avoid
1505 build problems. If Configure finds that gcc was built for a different
1506 operating system release than is running, it now gives a clearly visible
1507 warning that there may be trouble ahead.
1511 If binary compatibility with the 5.005 release is not wanted, Configure
1512 no longer suggests including the 5.005 modules in @INC.
1516 Configure C<-S> can now run non-interactively.
1520 Configure support for pdp11-style memory models has been removed due
1525 configure.gnu now works with options with whitespace in them.
1529 installperl now outputs everything to STDERR.
1533 $Config{byteorder} is now computed dynamically (this is more robust
1534 with "fat binaries" where an executable image contains binaries for
1535 more than one binary platform.)
1539 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1540 get appended to the $Config{archname} (also known as $^O) anymore.
1541 Instead, if you explicitly choose not to use perlio (Configure command
1542 line option -Uuseperlio), you will get "-stdio" appended.
1546 Another change related to the architecture name is that "-64all"
1547 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1548 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1552 In AFS installations one can configure the root of the AFS to be
1553 somewhere else than the default F</afs> by using the Configure
1554 parameter C<-Dafsroot=/some/where/else>.
1558 APPLLIB_EXP, a less-know configuration-time definition, has been
1559 documented. It can be used to prepend site-specific directories
1560 to Perl's default search path (@INC), see INSTALL for information.
1564 The version of Berkeley DB used when the Perl (and, presumably, the
1565 DB_File extension) was built is now available as
1566 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1567 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1568 DB_VERSION_PATCH_CFG> from C.
1572 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1573 has been documented in INSTALL.
1577 If you have CPAN access (either network or a local copy such as a
1578 CD-ROM) you can during specify extra modules to Configure to build and
1579 install with Perl using the -Dextras=... option. See INSTALL for
1584 In addition to config.over a new override file, config.arch, is
1585 available. That is supposed to be used by hints file writers for
1586 architecture-wide changes (as opposed to config.over which is for
1591 If your file system supports symbolic links you can build Perl outside
1592 of the source directory by
1594 mkdir /tmp/perl/build/directory
1595 cd /tmp/perl/build/directory
1596 sh /path/to/perl/source/Configure -Dmksymlinks ...
1598 This will create in /tmp/perl/build/directory a tree of symbolic links
1599 pointing to files in /path/to/perl/source. The original files are left
1600 unaffected. After Configure has finished you can just say
1604 and Perl will be built and tested, all in /tmp/perl/build/directory.
1608 For Perl developers several new make targets for profiling
1609 and debugging have been added, see L<perlhack>.
1615 Use of the F<gprof> tool to profile Perl has been documented in
1616 L<perlhack>. There is a make target called "perl.gprof" for
1617 generating a gprofiled Perl executable.
1621 If you have GCC 3, there is a make target called "perl.gcov" for
1622 creating a gcoved Perl executable for coverage analysis. See
1627 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1628 have been added, see L<perlhack> for more information about pixie and
1635 Guidelines of how to construct minimal Perl installations have
1636 been added to INSTALL.
1640 The Thread extension is now not built at all under ithreads
1641 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1642 Thread extension requires being Configured with C<-Duse5005threads>).
1644 But note that the Thread.pm interface is now shared by both
1649 The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
1650 floating-point numbers is now more picky about using sprintf %.*g
1651 rules for the conversion. Some platforms that used to use gcvt may
1652 now resort to the slower sprintf.
1656 =head2 New Or Improved Platforms
1658 For the list of platforms known to support Perl,
1659 see L<perlport/"Supported Platforms">.
1665 AIX dynamic loading should be now better supported.
1669 AIX should now work better with gcc, threads, and 64-bitness. Also the
1670 long doubles support in AIX should be better now. See L<perlaix>.
1674 After a long pause, AmigaOS has been verified to be happy with Perl.
1678 AtheOS ( http://www.atheos.cx/ ) is a new platform.
1682 BeOS has been reclaimed.
1686 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1690 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1694 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1695 have been regained. Many test suite tests still fail and the
1696 co-existence of Unicode and EBCDIC isn't quite settled, but the
1697 situation is much better than with Perl 5.6. See L<perlos390>,
1698 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1702 Building perl with -Duseithreads or -Duse5005threads now works under
1703 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1704 need a thread library package installed. See README.hpux.
1708 MacOS Classic (MacPerl has of course been available since
1709 perl 5.004 but now the source code bases of standard Perl
1710 and MacPerl have been synchronised)
1714 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1715 filesystems. (The case-insensitivity confused the Perl build process.)
1719 NCR MP-RAS is now supported.
1723 All the NetBSD specific patches (except for the installation
1724 specific ones) have been merged back to the main distribution.
1728 NetWare from Novell is now supported. See L<perlnetware>.
1732 NonStop-UX is now supported.
1736 NEC SUPER-UX is now supported.
1740 All the OpenBSD specific patches (except for the installation
1741 specific ones) have been merged back to the main distribution.
1745 Perl has been tested with the GNU pth userlevel thread package
1746 ( http://www.gnu.org/software/pth/pth.html ) . All but one thread
1747 test worked, and that one failure was because of test results arriving
1748 in unexpected order.
1752 Amdahl UTS UNIX mainframe platform is now supported.
1756 WinCE is now supported. See L<perlce>.
1760 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1761 support for dynamic loading. This is not selected by default,
1762 however, you must specify -Dusedl in the arguments of Configure.
1766 =head1 Selected Bug Fixes
1768 Numerous memory leaks and uninitialized memory accesses have been
1769 hunted down. Most importantly anonymous subs used to leak quite
1776 The autouse pragma didn't work for Multi::Part::Function::Names.
1780 caller() could cause core dumps in certain situations. Carp was sometimes
1781 affected by this problem.
1785 chop(@list) in list context returned the characters chopped in
1786 reverse order. This has been reversed to be in the right order.
1790 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1791 when building the Perl binary. The only exception to this is SunOS 4.x,
1796 The behaviour of non-decimal but numeric string constants such as
1797 "0x23" was platform-dependent: in some platforms that was seen as 35,
1798 in some as 0, in some as a floating point number (don't ask). This
1799 was caused by Perl using the operating system libraries in a situation
1800 where the result of the string to number conversion is undefined: now
1801 Perl consistently handles such strings as zero in numeric contexts.
1805 The order of DESTROYs has been made more predictable.
1809 Several debugger fixes: exit code now reflects the script exit code,
1810 condition C<"0"> now treated correctly, the C<d> command now checks
1811 line number, the C<$.> no longer gets corrupted, all debugger output
1812 now goes correctly to the socket if RemotePort is set.
1816 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1817 when statically building extensions into perl. This has been corrected.
1821 L<dprofpp> -R didn't work.
1825 C<*foo{FORMAT}> now works.
1828 Infinity is now recognized as a number.
1832 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1833 the Tk extension with 5.6.0.)
1837 Lexicals I: lexicals outside an eval "" weren't resolved
1838 correctly inside a subroutine definition inside the eval "" if they
1839 were not already referenced in the top level of the eval""ed code.
1843 Lexicals II: lexicals leaked at file scope into subroutines that
1844 were declared before the lexicals.
1848 Lexical warnings now propagating correctly between scopes
1849 and into C<eval "...">.
1853 C<use warnings qw(FATAL all)> did not work as intended. This has been
1858 warnings::enabled() now reports the state of $^W correctly if the caller
1859 isn't using lexical warnings.
1863 Line renumbering with eval and C<#line> now works.
1867 Fixed numerous memory leaks, especially in eval "".
1871 mkdir() now ignores trailing slashes in the directory name,
1872 as mandated by POSIX.
1876 Some versions of glibc have a broken modfl(). This affects builds
1877 with C<-Duselongdouble>. This version of Perl detects this brokenness
1878 and has a workaround for it. The glibc release 2.2.2 is known to have
1879 fixed the modfl() bug.
1883 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1884 return 27406, instead of 27047).
1888 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1889 more compatible with 5.005. Infinity is now recognised as a number.
1893 Numeric conversions did not recognize changes in the string value
1894 properly in certain circumstances.
1898 Attributes (like :shared) didn't work with our().
1902 our() variables will not cause "will not stay shared" warnings.
1906 "our" variables of the same name declared in two sibling blocks
1907 resulted in bogus warnings about "redeclaration" of the variables.
1908 The problem has been corrected.
1912 pack "Z" now correctly terminates the string with "\0".
1916 Fix password routines which in some shadow password platforms
1917 (e.g. HP-UX) caused getpwent() to return every other entry.
1921 The PERL5OPT environment variable (for passing command line arguments
1922 to Perl) didn't work for more than a single group of options.
1926 PERL5OPT with embedded spaces didn't work.
1930 printf() no longer resets the numeric locale to "C".
1934 C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1938 pos() did not return the correct value within s///ge in earlier
1939 versions. This is now handled correctly.
1943 Printing quads (64-bit integers) with printf/sprintf now works
1944 without the q L ll prefixes (assuming you are on a quad-capable platform).
1948 Regular expressions on references and overloaded scalars now work.
1952 Right-hand side magic (GMAGIC) could in many cases such as string
1953 concatenation be invoked too many times.
1957 scalar() now forces scalar context even when used in void context.
1961 SOCKS support is now much more robust.
1965 sort() arguments are now compiled in the right wantarray context
1966 (they were accidentally using the context of the sort() itself).
1967 The comparison block is now run in scalar context, and the arguments
1968 to be sorted are always provided list context.
1972 Changed the POSIX character class C<[[:space:]]> to include the (very
1973 rarely used) vertical tab character. Added a new POSIX-ish character
1974 class C<[[:blank:]]> which stands for horizontal whitespace
1975 (currently, the space and the tab).
1979 The tainting behaviour of sprintf() has been rationalized. It does
1980 not taint the result of floating point formats anymore, making the
1981 behaviour consistent with that of string interpolation.
1985 Some cases of inconsistent taint propagation (such as within hash
1986 values) have been fixed.
1990 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1991 of simple pattern matches. These are now handled better.
1995 Regular expression debug output (whether through C<use re 'debug'>
1996 or via C<-Dr>) now looks better.
2000 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
2005 Use of $& could trigger a core dump under some situations. This
2010 The regular expression captured submatches ($1, $2, ...) are now
2011 more consistently unset if the match fails, instead of leaving false
2012 data lying around in them.
2016 readline() on files opened in "slurp" mode could return an extra "" at
2017 the end in certain situations. This has been corrected.
2021 Autovivification of symbolic references of special variables described
2022 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
2027 Sys::Syslog ignored the C<LOG_AUTH> constant.
2031 All but the first argument of the IO syswrite() method are now optional.
2035 $AUTOLOAD, sort(), lock(), and spawning subprocesses
2036 in multiple threads simultaneously are now thread-safe.
2040 Tie::ARRAY SPLICE method was broken.
2044 Allow read-only string on left hand side of non-modifying tr///.
2048 If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
2049 correctly pass to it.
2053 Several Unicode fixes.
2059 BOMs (byte order marks) in the beginning of Perl files
2060 (scripts, modules) should now be transparently skipped.
2061 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
2065 The character tables have been updated to Unicode 3.1.1.
2069 Comparing with utf8 data does not magically upgrade non-utf8 data
2070 into utf8. (This was a problem for example if you were mixing data
2071 from I/O and Unicode data: your output might have got magically encoded
2076 Generating illegal Unicode code points like U+FFFE, or the UTF-16
2077 surrogates, now also generates an optional warning.
2081 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2085 Concatenation with the C<.> operator or via variable interpolation,
2086 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2087 substitution with C<s///>, single-quoted UTF8, should now work.
2091 The C<tr///> operator now works. Note that the C<tr///CU>
2092 functionality has been removed (but see pack('U0', ...)).
2096 C<eval "v200"> now works.
2100 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2101 This has been corrected.
2105 Zero entries were missing from the Unicode classes like C<IsDigit>.
2111 Large unsigned numbers (those above 2**31) could sometimes lose their
2112 unsignedness, causing bogus results in arithmetic operations.
2116 =head2 Platform Specific Changes and Fixes
2124 Perl now works on post-4.0 BSD/OSes.
2130 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2136 Numerous updates; currently synchronised with Cygwin 1.3.10.
2140 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2146 EPOC update after Perl 5.6.0. See README.epoc.
2152 Perl now works on post-3.0 FreeBSDs.
2158 README.hpux updated; C<Configure -Duse64bitall> now works.
2164 Numerous compilation flag and hint enhancements; accidental mixing
2165 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2175 Long doubles should now work (see INSTALL).
2179 Linux previously had problems related to sockaddrlen when using
2180 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
2188 Compilation of the standard Perl distribution in MacOS Classic should
2189 now work if you have the Metrowerks development environment and
2190 the missing Mac-specific toolkit bits. Contact the macperl mailing
2197 MPE/iX update after Perl 5.6.0. See README.mpeix.
2203 Perl now works on NetBSD/sparc.
2209 Now works with usethreads (see INSTALL).
2215 64-bitness using the Sun Workshop compiler now works.
2219 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2221 The operating system version letter now recorded in $Config{osvers}.
2222 Allow compiling with gcc (previously explicitly forbidden). Compiling
2223 with gcc still not recommended because buggy code results, even with
2230 Fixed various alignment problems that lead into core dumps either
2231 during build or later; no longer dies on math errors at runtime;
2232 now using full quad integers (64 bits), previously was using
2233 only 46 bit integers for speed.
2239 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2240 (see INSTALL); now works with Perl's malloc.
2242 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2243 unimplemented. It now works as documented.
2245 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2246 was that a pid of -1 would cause a wildcard search of all processes on
2247 the system. The most significant enhancement is that we can now
2248 usually get the completion status of a terminated process.
2250 POSIX-style signals are now emulated much better on VMS versions prior
2253 The C<system> function and backticks operator have improved
2254 functionality and better error handling.
2256 File access tests now use current process privileges rather than the
2257 user's default privileges, which could sometimes result in a mismatch
2258 between reported access and actual access.
2268 accept() no longer leaks memory.
2272 Borland C++ v5.5 is now a supported compiler that can build Perl.
2273 However, the generated binaries continue to be incompatible with those
2274 generated by the other supported compilers (GCC and Visual C++).
2278 Better chdir() return value for a non-existent directory.
2282 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2286 New %ENV entries now propagate to subprocesses.
2290 Current directory entries in %ENV are now correctly propagated to child
2295 $ENV{LIB} now used to search for libs under Visual C.
2299 fork() emulation has been improved in various ways, but still continues
2300 to be experimental. See L<perlfork> for known bugs and caveats.
2304 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2308 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2309 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2313 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2317 The makefiles now provide a single switch to bulk-enable all the features
2318 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2322 Allow REG_EXPAND_SZ keys in the registry.
2326 Can now send() from all threads, not just the first one.
2330 Fake signal handling reenabled, bugs and all.
2334 %SIG has been enabled under USE_ITHREADS, but its use is completely
2335 unsupported under all configurations.
2339 Less stack reserved per thread so that more threads can run
2340 concurrently. (Still 16M per thread.)
2344 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
2345 (works better when perl is running as service).
2349 Better UNC path handling under ithreads.
2353 wait(), waitpid() and backticks now return the correct exit status under
2358 winsock handle leak fixed.
2362 The Perl parser has been stress tested using both random input and
2363 Markov chain input and the few found crashes and lockups have been
2370 =head1 New or Changed Diagnostics
2376 The lexical warnings category "deprecated" is no longer a sub-category
2377 of the "syntax" category. It is now a top-level category in its own
2382 All regular expression compilation error messages are now hopefully
2383 easier to understand both because the error message now comes before
2384 the failed regex and because the point of failure is now clearly
2385 marked by a C<E<lt>-- HERE> marker.
2389 The various "opened only for", "on closed", "never opened" warnings
2390 drop the C<main::> prefix for filehandles in the C<main> package,
2391 for example C<STDIN> instead of C<main::STDIN>.
2395 The "Unrecognized escape" warning has been extended to include C<\8>,
2396 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2400 Two new debugging options have been added: if you have compiled your
2401 Perl with debugging, you can use the -DT and -DR options to trace
2402 tokenising and to add reference counts to displaying variables,
2407 The debugger (perl5db.pl) has been modified to present a more
2408 consistent commands interface, via (CommandSet=580). perl5db.t was
2409 also added to test the changes, and as a placeholder for further tests.
2415 The debugger has a new C<dumpDepth> option to control the maximum
2416 depth to which nested structures are dumped. The C<x> command has
2417 been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a
2418 depth of at most I<N> levels.
2422 The debugger can now show lexical variables if you have the CPAN
2423 module PadWalker installed.
2427 If an attempt to use a (non-blessed) reference as an array index
2428 is made, a warning is given.
2432 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2433 now give a warning. This may be a problem for generated and evaled
2438 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2439 using the C<"C"> format you will get an optional warning. Similarly
2440 for the C<"c"> format and a number less than -128 or more than 127.
2444 Certain regex modifiers such as C<(?o)> make sense only if applied to
2445 the entire regex. You will get an optional warning if you try to do
2450 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2451 has been deprecated for a while. Now you will get an optional warning.
2455 Using C<sort> in scalar context now issues an optional warning.
2456 This didn't do anything useful, as the sort was not performed.
2460 =head1 Changed Internals
2466 perlapi.pod (a companion to perlguts) now attempts to document the
2471 You can now build a really minimal perl called microperl.
2472 Building microperl does not require even running Configure;
2473 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2474 many assumptions, some of which may be too bold; the resulting
2475 executable may crash or otherwise misbehave in wondrous ways.
2476 For careful hackers only.
2480 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2481 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2482 interfaces to the publicised API. For the full list of the available
2483 APIs see L<perlapi>.
2487 Made possible to propagate customised exceptions via croak()ing.
2491 Now xsubs can have attributes just like subs. (Well, at least the
2492 built-in attributes.)
2496 dTHR and djSP have been obsoleted; the former removed (because it's
2497 a no-op) and the latter replaced with dSP.
2501 PERL_OBJECT has been completely removed.
2505 The MAGIC constants (e.g. C<'P'>) have been macrofied
2506 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2507 and maintainability.
2511 The regex compiler now maintains a structure that identifies nodes in
2512 the compiled bytecode with the corresponding syntactic features of the
2513 original regex expression. The information is attached to the new
2514 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2515 complete information.
2519 The C code has been made much more C<gcc -Wall> clean. Some warning
2520 messages still remain in some platforms, so if you are compiling with
2521 gcc you may see some warnings about dubious practices. The warnings
2522 are being worked on.
2526 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2530 Documentation on how to use the Perl source repository has been added
2531 to F<Porting/repository.pod>.
2535 There are now several profiling make targets.
2539 =head1 Security Vulnerability Closed
2541 (This change was already made in 5.7.0 but bears repeating here.)
2543 A potential security vulnerability in the optional suidperl component
2544 of Perl was identified in August 2000. suidperl is neither built nor
2545 installed by default. As of November 2001 the only known vulnerable
2546 platform is Linux, most likely all Linux distributions. CERT and
2547 various vendors and distributors have been alerted about the vulnerability.
2548 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2549 for more information.
2551 The problem was caused by Perl trying to report a suspected security
2552 exploit attempt using an external program, /bin/mail. On Linux
2553 platforms the /bin/mail program had an undocumented feature which
2554 when combined with suidperl gave access to a root shell, resulting in
2555 a serious compromise instead of reporting the exploit attempt. If you
2556 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2557 suidperl is not installed, you are safe.
2559 The exploit attempt reporting feature has been completely removed from
2560 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2561 from all the Perl 5.7 releases), so that particular vulnerability
2562 isn't there anymore. However, further security vulnerabilities are,
2563 unfortunately, always possible. The suidperl functionality is most
2564 probably going to be removed in Perl 5.10. In any case, suidperl
2565 should only be used by security experts who know exactly what they are
2566 doing and why they are using suidperl instead of some other solution
2567 such as sudo ( see http://www.courtesan.com/sudo/ ).
2571 Several new tests have been added, especially for the F<lib>
2572 subsection. There are now about 56 000 individual tests (spread over
2573 about 620 test scripts), in the regression suite (5.6.1 has about
2574 11700 tests, in 258 test scripts) Many of the new tests are introduced
2575 by the new modules, but still in general Perl is now more thoroughly
2578 Because of the large number of tests, running the regression suite
2579 will take considerably longer time than it used to: expect the suite
2580 to take up to 4-5 times longer to run than in perl 5.6. In a really
2581 fast machine you can hope to finish the suite in about 6-8 minutes
2584 The tests are now reported in a different order than in earlier Perls.
2585 (This happens because the test scripts from under t/lib have been moved
2586 to be closer to the library/extension they are testing.)
2588 =head1 Known Problems
2596 In AIX 4.2 Perl extensions that use C++ functions that use statics
2597 may have problems in that the statics are not getting initialized.
2598 In newer AIX releases this has been solved by linking Perl with
2599 the libC_r library, but unfortunately in AIX 4.2 the said library
2600 has an obscure bug where the various functions related to time
2601 (such as time() and gettimeofday()) return broken values, and
2602 therefore in AIX 4.2 Perl is not linked against the libC_r.
2606 vac 5.0.0.0 May Produce Buggy Code For Perl
2608 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2609 resulting in few random tests failing, but when the failing tests
2610 are run by hand, they succeed. We suggest upgrading to at least
2611 vac version 5.0.1.0, that has been known to compile Perl correctly.
2612 "lslpp -L|grep vac.C" will tell you the vac version. See README.aix.
2616 If building threaded Perl, you may get compilation warning from pp_sys.c:
2618 "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
2620 This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()
2621 having slightly different types for their first argument.
2625 =head2 Amiga Perl Invoking Mystery
2627 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2628 works, but for example C<bin:perl -v> doesn't. The exact reason isn't
2629 known but the current suspect is the F<ixemul> library.
2631 =head2 FreeBSD Failing locale Test 117 For ISO8859-15 Locales
2633 The ISO8859-15 locales may fail the locale test 117 in FreeBSD.
2634 This is caused by the characters \xFF (y with diaeresis) and \xBE
2635 (Y with diaeresis) not behaving correctly when being matched
2638 =head2 mod_perl 1.26 Doesn't Build With Threaded Perl
2640 Use mod_perl 1.27 or higher.
2642 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2644 Don't panic. Read INSTALL 'make test' section instead.
2646 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2648 If perl is configured with -Duse64bitall, the successful result of the
2649 subtest 10 of lib/posix may arrive before the successful result of the
2650 subtest 9, which confuses the test harness so much that it thinks the
2653 =head2 Linux With Sfio Fails op/misc Test 48
2659 Please remember to set your environment variable LC_ALL to "C"
2660 (setenv LC_ALL C) before running "make test" to avoid a lot of
2661 warnings about the broken locales of Mac OS X.
2663 The following tests are known to fail:
2665 Failed Test Stat Wstat Total Fail Failed List of Failed
2666 -------------------------------------------------------------------------
2667 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2668 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2669 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2671 If you are building on a UFS partition, you will also probably see
2672 t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not
2673 supporting inode change time.
2675 =head2 op/sprintf tests 91, 129, and 130
2677 The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.
2678 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2680 The test 91 is known to fail at QNX6 (nto), because C<sprintf '%e',0>
2681 incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>.
2683 For the tests 129 and 130 the failing platforms do not comply with
2684 the ANSI C Standard, line 19ff on page 134 of ANSI X3.159 1989 to
2685 be exact. (They produce something other than "1" and "-1" when
2686 formatting 0.6 and -0.6 using the printf format "%.0f", most often
2687 they produce "0" and "-0".)
2689 =head2 Failure of Thread (5.005-style) tests
2691 B<Note that support for 5.005-style threading remains experimental
2692 and practically unsupported.>
2694 The following tests are known to fail due to fundamental problems in
2695 the 5.005 threading implementation. These are not new failures--Perl
2696 5.005_0x has the same bugs, but didn't have these tests.
2698 ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7
2699 ../lib/English.t 2 512 54 2 3.70% 2-3
2700 ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3
2701 ../lib/Filter/Simple/t/filter_onl 9 3 33.33% 1-2 5
2702 ../lib/autouse.t 10 1 10.00% 4
2703 op/flip.t 15 1 6.67% 15
2705 These failures are unlikely to get fixed as the 5.005-style
2706 threads are considered fundamentally broken.
2710 Failed Test Stat Wstat Total Fail Failed List of Failed
2711 -------------------------------------------------------------------------
2712 ../ext/Socket/socketpair.t 1 256 45 1 2.22% 12
2713 ../lib/Math/Trig.t 26 1 3.85% 25
2714 ../lib/warnings.t 460 1 0.22% 425
2715 io/fs.t 36 1 2.78% 31
2716 op/numconvert.t 1440 13 0.90% 208 509-510
2717 657-658 665-666 829-830 989-990 1149-1150
2719 =head2 UNICOS and UNICOS/mk
2721 The io/fs test #31 is failing because in UNICOS and UNICOS/mk the Perl
2722 truncate() cannot be used to grow the size of filehandles, only to
2723 reduce the size. The workaround is to truncate files instead of
2732 During Configure the test
2734 Guessing which symbols your C compiler and preprocessor define...
2736 will probably fail with error messages like
2738 CC-20 cc: ERROR File = try.c, Line = 3
2739 The identifier "bad" is undefined.
2741 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
2744 CC-65 cc: ERROR File = try.c, Line = 3
2745 A semicolon is expected at this point.
2747 This is caused by a bug in awk utility of UNICOS/mk. You can ignore
2748 the error, but it does cause a slight problem: you cannot fully
2749 benefit from the h2ph utility (see L<h2ph>) that can be used to
2750 convert C headers to Perl libraries, mainly used to be able to access
2751 from Perl the constants defined using C preprocessor, cpp. Because of
2752 the above error parts of the converted headers will be invisible.
2753 Luckily, these days the need for h2ph is rare.
2757 If building Perl with the interpreter threads (ithreads), the
2758 getgrent(), getgrnam(), and getgrgid() functions cannot return the
2759 list of the group members due to a bug in the multithreaded support of
2760 UNICOS/mk. What this means that in list context the functions will
2761 return only three values, not four.
2767 There are a few known test failures, see L<perluts>.
2771 There should be no reported test failures with a default configuration,
2772 though there are a number of tests marked TODO that point to areas
2773 needing further debugging and/or porting work.
2777 In multi-CPU boxes there are some problems with the I/O buffering:
2778 some output may appear twice. The following Win32 failures are known
2781 Failed Test Stat Wstat Total Fail Failed List of Failed
2782 -------------------------------------------------------------------------
2783 ..\ext/threads/t/end.t 6 4 66.67% 3-6
2785 =head2 Localising a Tied Variable Leaks Memory
2788 tie my %tie_hash => 'Tie::StdHash';
2792 local($tie_hash{Foo}) = 1; # leaks
2794 Code like the above is known to leak memory every time the local()
2797 =head2 z/OS (OS/390)
2799 z/OS has rather many test failures but the situation is actually
2800 better than it was in 5.6.0, it's just that so many new modules and
2801 tests have been added.
2803 Failed Test Stat Wstat Total Fail Failed List of Failed
2804 -------------------------------------------------------------------------
2805 ../ext/Data/Dumper/t/dumper.t 321 2 0.62% 311 314
2806 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5
2807 ../lib/utf8.t 94 13 13.83% 27 30-31 43 46 73
2810 ../lib/Benchmark.t 1 256 159 1 0.63% 75
2811 ../lib/ExtUtils/t/Constant.t 27 19 70.37% 5-23
2812 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9
2813 op/pat.t 864 9 1.04% 242-243 665 776
2815 op/sprintf.t 224 3 1.34% 98 100 136
2816 op/tr.t 97 5 5.15% 63 71-74
2817 uni/fold.t 767 8 1.04% 25-26 62 169 196
2819 60 tests and 384 subtests skipped.
2821 =head2 Localising Tied Arrays and Hashes Is Broken
2825 doesn't work as one would expect: the old value is restored
2828 =head2 Self-tying of Arrays and Hashes Is Forbidden
2830 Self-tying of arrays and hashes is broken in rather deep and
2831 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2832 frustrated at the mysterious results (core dumps, most often) it is
2833 for now forbidden (you will get a fatal error even from an attempt).
2835 =head2 Building Extensions Can Fail Because Of Largefiles
2837 Some extensions like mod_perl are known to have issues with
2838 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2839 default to 64 bits wide, where supported. Modules may fail to compile
2840 at all or compile and work incorrectly. Currently there is no good
2841 solution for the problem, but Configure now provides appropriate
2842 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2843 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2844 having problems can try configuring themselves without the
2845 largefileness. This is admittedly not a clean solution, and the
2846 solution may not even work at all. One potential failure is whether
2847 one can (or, if one can, whether it's a good idea) link together at
2848 all binaries with different ideas about file offsets, all this is
2851 =head2 Unicode Support on EBCDIC Still Spotty
2853 Though mostly working, Unicode support still has problem spots on
2854 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2855 regular expression constructs for code points less than 256: the
2856 pP are testing for Unicode code points, not knowing about EBCDIC.
2858 =head2 The Compiler Suite Is Still Experimental
2860 The compiler suite is slowly getting better but it continues to be
2861 highly experimental. Use in production environments is discouraged.
2863 =head2 The Long Double Support Is Still Experimental
2865 The ability to configure Perl's numbers to use "long doubles",
2866 floating point numbers of hopefully better accuracy, is still
2867 experimental. The implementations of long doubles are not yet
2868 widespread and the existing implementations are not quite mature
2869 or standardised, therefore trying to support them is a rare
2870 and moving target. The gain of more precision may also be offset
2871 by slowdown in computations (more bits to move around, and the
2872 operations are more likely to be executed by less optimised
2875 =head2 Seen In Perl 5.7 But Gone Now
2877 C<Time::Piece> (previously known as C<Time::Object>) was removed
2878 because it was felt that it didn't have enough value in it to be a
2879 core module. It is still a useful module, though, and is available
2882 =head1 Reporting Bugs
2884 If you find what you think is a bug, you might check the articles
2885 recently posted to the comp.lang.perl.misc newsgroup and the perl
2886 bug database at http://bugs.perl.org/ There may also be
2887 information at http://www.perl.com/ , the Perl Home Page.
2889 If you believe you have an unreported bug, please run the B<perlbug>
2890 program included with your release. Be sure to trim your bug down
2891 to a tiny but sufficient test case. Your bug report, along with the
2892 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2893 analysed by the Perl porting team.
2897 The F<Changes> file for exhaustive details on what changed.
2899 The F<INSTALL> file for how to build Perl.
2901 The F<README> file for general stuff.
2903 The F<Artistic> and F<Copying> files for copyright information.
2907 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.