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 Binary Incompatibility
51 B<Perl 5.8 is not binary compatible with earlier releases of Perl.>
53 B<You have to recompile your XS modules.>
55 (Pure Perl modules should continue to work.)
57 The major reason for the discontinuity is the new IO architecture
58 called PerlIO. PerlIO is the default configuration because without
59 it many new features of Perl 5.8 cannot be used. In other words:
60 you just have to recompile your modules containing XS code, sorry
63 In future releases of Perl, non-PerlIO aware XS modules may become
64 completely unsupported. This shouldn't be too difficult for module
65 authors, however: PerlIO has been designed as a drop-in replacement
66 (at the source code level) for the stdio interface.
68 Depending on your platform, there are also other reasons why
69 we decided to break binary compatibility, please read on.
71 =head2 64-bit platforms and malloc
73 If your pointers are 64 bits wide, the Perl malloc is no longer being
74 used because it does not work well with 8-byte pointers. Also,
75 usually the system mallocs on such platforms are much better optimized
76 for such large memory models than the Perl malloc. Some memory-hungry
77 Perl applications like the PDL don't work well with Perl's malloc.
78 Finally, other applications than Perl (such as mod_perl) tend to prefer
79 the system malloc. Such platforms include Alpha and 64-bit HPPA,
82 =head2 AIX Dynaloading
84 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
85 dlopen interface of AIX instead of the old emulated interface. This
86 change will probably break backward compatibility with compiled
87 modules. The change was made to make Perl more compliant with other
88 applications like mod_perl which are using the AIX native interface.
90 =head2 Attributes for C<my> variables now handled at run-time.
92 The C<my EXPR : ATTRS> syntax now applies variable attributes at
93 run-time. (Subroutine and C<our> variables still get attributes applied
94 at compile-time.) See L<attributes> for additional details. In particular,
95 however, this allows variable attributes to be useful for C<tie> interfaces,
96 which was a deficiency of earlier releases. Note that the new semantics
97 doesn't work with the Attribute::Handlers module (as of version 0.76).
99 =head2 Socket Extension Dynamic in VMS
101 The Socket extension is now dynamically loaded instead of being
102 statically built in. This may or may not be a problem with ancient
103 TCP/IP stacks of VMS: we do not know since we weren't able to test
104 Perl in such configurations.
106 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
108 Perl now uses IEEE format (T_FLOAT) as the default internal floating
109 point format on OpenVMS Alpha, potentially breaking binary compatibility
110 with external libraries or existing data. G_FLOAT is still available as
111 a configuration option. The default on VAX (D_FLOAT) has not changed.
113 =head2 New Unicode Properties
115 Unicode I<scripts> are now supported. Scripts are similar to (and superior
116 to) Unicode I<blocks>. The difference between scripts and blocks is that
117 scripts are the glyphs used by a language or a group of languages, while
118 the blocks are more artificial groupings of (mostly) 256 characters based
119 on the Unicode numbering.
121 In general, scripts are more inclusive, but not universally so. For
122 example, while the script C<Latin> includes all the Latin characters and
123 their various diacritic-adorned versions, it does not include the various
124 punctuation or digits (since they are not solely C<Latin>).
126 A number of other properties are now supported, including C<\p{L&}>,
127 C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> and
128 C<\p{SpacePerl}> (along with their C<\P{...}> versions, of course).
129 See L<perlunicode> for details, and more additions.
131 The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
132 are now almost always optional. The only exception is that a C<In> prefix
133 is required to signify a Unicode block when a block name conflicts with a
134 script name. For example, C<\p{Tibetan}> refers to the script, while
135 C<\p{InTibetan}> refers to the block. When there is no name conflict, you
136 can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
137 to be safe, it's probably best to always use the C<In>).
139 =head2 REF(...) Instead Of SCALAR(...)
141 A reference to a reference now stringifies as "REF(0x81485ec)" instead
142 of "SCALAR(0x81485ec)" in order to be more consistent with the return
145 =head2 pack/unpack D/F recycled
147 The undocumented pack/unpack template letters D/F have been recycled
148 for better use: now they stand for long double (if supported by the
149 platform) and NV (Perl internal floating point type). (They used
150 to be aliases for d/f, but you never knew that.)
158 The semantics of bless(REF, REF) were unclear and until someone proves
159 it to make some sense, it is forbidden.
163 The obsolete chat2 library that should never have been allowed
164 to escape the laboratory has been decommissioned.
168 The builtin dump() function has probably outlived most of its
169 usefulness. The core-dumping functionality will remain in future
170 available as an explicit call to C<CORE::dump()>, but in future
171 releases the behaviour of an unqualified C<dump()> call may change.
175 The very dusty examples in the eg/ directory have been removed.
176 Suggestions for new shiny examples welcome but the main issue is that
177 the examples need to be documented, tested and (most importantly)
182 The (bogus) escape sequences \8 and \9 now give an optional warning
183 ("Unrecognized escape passed through"). There is no need to \-escape
188 The list of filenames from glob() (or <...>) is now by default sorted
189 alphabetically to be csh-compliant (which is what happened before
190 in most UNIX platforms). (bsd_glob() does still sort platform
191 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
195 Spurious syntax errors generated in certain situations, when glob()
196 caused File::Glob to be loaded for the first time, have been fixed.
200 Although "you shouldn't do that", it was possible to write code that
201 depends on Perl's hashed key order (Data::Dumper does this). The new
202 algorithm "One-at-a-Time" produces a different hashed key order.
203 More details are in L</"Performance Enhancements">.
207 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
208 In future releases this may become a fatal error.
212 The C<package;> syntax (C<package> without an argument) has been
213 deprecated. Its semantics were never that clear and its
214 implementation even less so. If you have used that feature to
215 disallow all but fully qualified variables, C<use strict;> instead.
219 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
220 recognised but now cause fatal errors. The previous behaviour of
221 ignoring them by default and warning if requested was unacceptable
222 since it, in a way, falsely promised that the features could be used.
226 The current user-visible implementation of pseudo-hashes (the weird
227 use of the first array element) is deprecated starting from Perl 5.8.0
228 and will be removed in Perl 5.10.0, and the feature will be
229 implemented differently. Not only is the current interface rather
230 ugly, but the current implementation slows down normal array and hash
231 use quite noticeably. The C<fields> pragma interface will remain
232 available. The I<restricted hashes> interface is expected to
233 be the replacement interface (see L<Hash::Util>).
237 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
241 After years of trying, suidperl is considered to be too complex to
242 ever be considered truly secure. The suidperl functionality is likely
243 to be removed in a future release.
247 The 5.005 threads model (module C<Thread>) is deprecated and expected
248 to be removed in Perl 5.10. Multithreaded code should be migrated to
249 the new ithreads model (see L<threads>, L<threads::shared> and
254 The long deprecated uppercase aliases for the string comparison
255 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
259 The tr///C and tr///U features have been removed and will not return;
260 the interface was a mistake. Sorry about that. For similar
261 functionality, see pack('U0', ...) and pack('C0', ...).
265 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
266 The prototypes are now checked better at compile-time for invalid
267 syntax. An optional warning is generated ("Illegal character in
268 prototype...") but this may be upgraded to a fatal error in a future
273 The existing behaviour when localising tied arrays and hashes is wrong,
274 and will be changed in a future release, so do not rely on the existing
275 behaviour. See L<"Localising Tied Arrays and Hashes Is Broken">.
279 =head1 Core Enhancements
281 =head2 PerlIO is Now The Default
287 IO is now by default done via PerlIO rather than system's "stdio".
288 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
289 handle's behaviour. Layers can be specified at open time via 3-arg
292 open($fh,'>:crlf :utf8', $path) || ...
294 or on already opened handles via extended C<binmode>:
296 binmode($fh,':encoding(iso-8859-7)');
298 The built-in layers are: unix (low level read/write), stdio (as in
299 previous Perls), perlio (re-implementation of stdio buffering in a
300 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
301 but available on any platform). A mmap layer may be available if
302 platform supports it (mostly UNIXes).
304 Layers to be applied by default may be specified via the 'open' pragma.
306 See L</"Installation and Configuration Improvements"> for the effects
307 of PerlIO on your architecture name.
311 File handles can be marked as accepting Perl's internal encoding of Unicode
312 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
314 open($fh,">:utf8","Uni.txt");
316 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
317 for you since it's not UTF-8 what you will be getting but instead
318 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
319 http://www.unicode.org/unicode/reports/tr16/ for more information.
320 In future releases this naming may change.
324 File handles can translate character encodings from/to Perl's internal
325 Unicode form on read/write via the ":encoding()" layer.
329 File handles can be opened to "in memory" files held in Perl scalars via:
331 open($fh,'>', \$variable) || ...
335 Anonymous temporary files are available without need to
336 'use FileHandle' or other module via
338 open($fh,"+>", undef) || ...
340 That is a literal undef, not an undefined value.
344 The list form of C<open> is now implemented for pipes (at least on UNIX):
346 open($fh,"-|", 'cat', '/etc/motd')
348 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
353 If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG)
354 contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
355 the default encoding of your STDIN, STDOUT, and STDERR, and of
356 B<any subsequent file open>, is UTF-8.
360 =head2 Restricted Hashes
362 A restricted hash is restricted to a certain set of keys, no keys
363 outside the set can be added. Also individual keys can be restricted
364 so that the key cannot be deleted and the value cannot be changed.
365 No new syntax is involved: the Hash::Util module is the interface.
369 Perl used to be fragile in that signals arriving at inopportune moments
370 could corrupt Perl's internal state. Now Perl postpones handling of
371 signals until it's safe (between opcodes).
373 This change may have surprising side effects because signals no longer
374 interrupt Perl instantly. Perl will now first finish whatever it was
375 doing, like finishing an internal operation (like sort()) or an
376 external operation (like an I/O operation), and only then look at any
377 arrived signals (and before starting the next operation). No more corrupt
378 internal state since the current operation is always finished first,
379 but the signal may take more time to get heard. Note that breaking
380 out from potentially blocking operations should still work, though.
382 =head2 Unicode Overhaul
384 Unicode in general should be now much more usable than in Perl 5.6.0
385 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
386 regular expressions should work now, Unicode in tr/// should work now,
387 Unicode in I/O should work now. See L<perluniintro> for introduction
388 and L<perlunicode> for details.
394 The Unicode Character Database coming with Perl has been upgraded
395 to Unicode 3.2.0. For more information, see http://www.unicode.org/ .
399 For developers interested in enhancing Perl's Unicode capabilities:
400 almost all the UCD files are included with the Perl distribution in
401 the F<lib/unicore> subdirectory. The most notable omission, for space
402 considerations, is the Unihan database.
406 The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
407 C isblank(), that is, it contains only "horizontal whitespace" (the space
408 character is, the newline isn't), and the "SpacePerl" is the Unicode
409 equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
410 tabulator character, whereas C<\s> doesn't.)
412 See "New Unicode Properties" earlier in this document for additional
413 information on changes with Unicode properties.
417 =head2 Understanding of Numbers
419 In general a lot of fixing has happened in the area of Perl's
420 understanding of numbers, both integer and floating point. Since in
421 many systems the standard number parsing functions like C<strtoul()>
422 and C<atof()> seem to have bugs, Perl tries to work around their
423 deficiencies. This results hopefully in more accurate numbers.
425 Perl now tries internally to use integer values in numeric conversions
426 and basic arithmetics (+ - * /) if the arguments are integers, and
427 tries also to keep the results stored internally as integers.
428 This change leads to often slightly faster and always less lossy
429 arithmetics. (Previously Perl always preferred floating point numbers
432 =head2 Miscellaneous Changes
438 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
439 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
443 The $Config{byteorder} (and corresponding BYTEORDER in config.h) was
444 previously wrong in platforms if sizeof(long) was 4, but sizeof(IV)
445 was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321),
446 but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321).
447 (This problem didn't affect Windows platforms.)
449 Also, $Config{byteorder} is now computed dynamically--this is more
450 robust with "fat binaries" where an executable image contains binaries
451 for more than one binary platform, and when cross-compiling.
455 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
456 in multiple arguments.)
460 The builtin dump() now gives an optional warning
461 C<dump() better written as CORE::dump()>,
462 meaning that by default C<dump(...)> is resolved as the builtin
463 dump() which dumps core and aborts, not as (possibly) user-defined
464 C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
465 (The whole dump() feature is to considered deprecated, and possibly
466 removed/changed in future releases.)
470 chomp() and chop() are now overridable. Note, however, that their
471 prototype (as given by C<prototype("CORE::chomp")> is undefined,
472 because it cannot be expressed and therefore one cannot really write
473 replacements to override these builtins.
477 END blocks are now run even if you exit/die in a BEGIN block.
478 Internally, the execution of END blocks is now controlled by
479 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
480 behaviour for Perl embedders. This will default in 5.10. See
485 Formats now support zero-padded decimal fields.
489 Lvalue subroutines can now return C<undef> in list context.
490 However, the lvalue subroutine feature still remains experimental.
494 A lost warning "Can't declare ... dereference in my" has been
495 restored (Perl had it earlier but it became lost in later releases.)
499 A new special regular expression variable has been introduced:
500 C<$^N>, which contains the most-recently closed group (submatch).
504 C<no Module;> now works even if there is no "sub unimport" in the Module.
508 The numerical comparison operators return C<undef> if either operand
509 is a NaN. Previously the behaviour was unspecified.
513 The following builtin functions are now overridable: each(), keys(),
514 pop(), push(), shift(), splice(), unshift().
518 C<pack() / unpack()> now can group template letters with C<()> and then
519 apply repetition/count modifiers on the groups.
523 C<pack() / unpack()> can now process the Perl internal numeric types:
524 IVs, UVs, NVs-- and also long doubles, if supported by the platform.
525 The template letters are C<j>, C<J>, C<F>, and C<D>.
529 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
533 my __PACKAGE__ $obj now works.
537 POSIX::sleep() now returns the number of I<unslept> seconds
538 (as the POSIX standard says), as opposed to CORE::sleep() which
539 returns the number of slept seconds.
543 The printf() and sprintf() now support parameter reordering using the
544 C<%\d+\$> and C<*\d+\$> syntaxes. For example
546 print "%2\$s %1\$s\n", "foo", "bar";
548 will print "bar foo\n". This feature helps in writing
549 internationalised software, and in general when the order
550 of the parameters can vary.
554 prototype(\&) is now available.
558 prototype(\[$@%&]) is now available to implicitly create references
559 (useful for example if you want to emulate the tie() interface).
563 A new command-line option, C<-t> is available. It is the
564 little brother of C<-T>: instead of dying on taint violations,
565 lexical warnings are given. B<This is only meant as a temporary
566 debugging aid while securing the code of old legacy applications.
567 This is not a substitute for -T.>
571 In other taint news, the C<exec LIST> and C<system LIST> have now been
572 considered too risky (think C<exec @ARGV>: it can start any program
573 with any arguments), and now the said forms cause a warning.
574 You should carefully launder the arguments to guarantee their
575 validity. In future releases of Perl the forms will become fatal
576 errors so consider starting laundering now.
580 Tied hash interfaces are now required to have the EXISTS and DELETE
581 methods (either own or inherited).
585 If tr/// is just counting characters, it doesn't attempt to
590 untie() will now call an UNTIE() hook if it exists. See L<perltie>
595 L<utime> now supports C<utime undef, undef, @files> to change the
596 file timestamps to the current time.
600 The rules for allowing underscores (underbars) in numeric constants
601 have been relaxed and simplified: now you can have an underscore
602 simply B<between digits>.
606 Rather than relying on C's argv[0] (which may not contain a full pathname)
607 where possible $^X is now set by asking the operating system.
608 (eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD)
612 A new variable, C<${^TAINT}>, indicates whether taint mode is enabled.
616 You can now override the readline() builtin, and this overrides also
617 the <FILEHANDLE> angle bracket operator.
621 The command-line options -s and -F are now recognized on the shebang
626 Use of the C</c> match modifier without an accompanying C</g> modifier
627 elicits a new warning: C<Use of /c modifier is meaningless without /g>.
629 Use of C</c> in substitutions, even with C</g>, elicits
630 C<Use of /c modifier is meaningless in s///>.
632 Use of C</g> with C<split> elicits C<Use of /g modifier is meaningless
637 =head1 Modules and Pragmata
639 =head2 New Modules and Pragmata
645 C<Attribute::Handlers> allows a class to define attribute handlers.
648 use Attribute::Handlers;
649 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
651 # later, in some package using or inheriting from MyPack...
653 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
655 Both variables and routines can have attribute handlers. Handlers can
656 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
657 exact compilation phase (BEGIN, CHECK, INIT, or END).
658 See L<Attribute::Handlers>.
662 C<B::Concise>, by Stephen McCamant, is a new compiler backend for
663 walking the Perl syntax tree, printing concise info about ops.
664 The output is highly customisable. See L<B::Concise>.
668 The new bignum, bigint, and bigrat pragmas, by Tels, implement
669 transparent bignum support (using the Math::BigInt, Math::BigFloat,
670 and Math::BigRat backends).
674 C<Class::ISA>, by Sean Burke, is a module for reporting the search
675 path for a class's ISA tree. See L<Class::ISA>.
679 C<Cwd> now has a split personality: if possible, an XS extension is
680 used, (this will hopefully be faster, more secure, and more robust)
681 but if not possible, the familiar Perl implementation is used.
685 C<Devel::PPPort>, originally by Kenneth Albanowski and now
686 maintained by Paul Marquess, has been added. It is primarily used
687 by C<h2xs> to enhance portability of XS modules between different
688 versions of Perl. See L<Devel::PPPort>.
692 C<Digest>, frontend module for calculating digests (checksums), from
693 Gisle Aas, has been added. See L<Digest>.
697 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
698 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
700 use Digest::MD5 'md5_hex';
702 $digest = md5_hex("Thirsty Camel");
704 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
706 NOTE: the C<MD5> backward compatibility module is deliberately not
707 included since its further use is discouraged.
711 C<Encode>, originally by Nick Ing-Simmons and now maintained by Dan
712 Kogai, provides a mechanism to translate between different character
713 encodings. Support for Unicode, ISO-8859-1, and ASCII are compiled in
714 to the module. Several other encodings (like the rest of the
715 ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese,
716 Japanese, and Korean encodings) are included and can be loaded at
717 runtime. (For space considerations, the largest Chinese encodings
718 have been separated into their own CPAN module, Encode::HanExtra,
719 which Encode will use if available). See L<Encode>.
721 Any encoding supported by Encode module is also available to the
722 ":encoding()" layer if PerlIO is used.
726 C<Hash::Util> is the interface to the new I<restricted hashes>
727 feature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and
728 Michael Schwern.) See L<Hash::Util>.
732 C<I18N::Langinfo> can be used to query locale information.
733 See L<I18N::Langinfo>.
737 C<I18N::LangTags>, by Sean Burke, has functions for dealing with
738 RFC3066-style language tags. See L<I18N::LangTags>.
742 C<ExtUtils::Constant>, by Nicholas Clark, is a new tool for extension
743 writers for generating XS code to import C header constants.
744 See L<ExtUtils::Constant>.
748 C<Filter::Simple>, by Damian Conway, is an easy-to-use frontend to
749 Filter::Util::Call. See L<Filter::Simple>.
755 use Filter::Simple sub {
756 while (my ($from, $to) = splice @_, 0, 2) {
765 use MyFilter qr/red/ => 'green';
767 print "red\n"; # this code is filtered, will print "green\n"
768 print "bored\n"; # this code is filtered, will print "bogreen\n"
772 print "red\n"; # this code is not filtered, will print "red\n"
776 C<File::Temp>, by Tim Jenness, allows one to create temporary files and
777 directories in an easy, portable, and secure way. See L<File::Temp>.
781 C<Filter::Util::Call>, by Paul Marquess, provides you with the
782 framework to write I<source filters> in Perl. For most uses, the
783 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
787 C<if>, by Ilya Zakharevich, is a new pragma for conditional inclusion
792 L<libnet>, by Graham Barr, is a collection of perl5 modules related
793 to network programming. See L<Net::FTP>, L<Net::NNTP>, L<Net::Ping>
794 (not part of libnet, but related), L<Net::POP3>, L<Net::SMTP>,
797 Perl installation leaves libnet unconfigured; use F<libnetcfg>
802 C<List::Util>, by Graham Barr, is a selection of general-utility
803 list subroutines, such as sum(), min(), first(), and shuffle().
808 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>
809 C<Locale::Language>, and L<Locale::Script>, by Neil Bowers, have
810 been added. They provide the codes for various locale standards, such
811 as "fr" for France, "usd" for US Dollar, and "ja" for Japanese.
815 $country = code2country('jp'); # $country gets 'Japan'
816 $code = country2code('Norway'); # $code gets 'no'
818 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
819 and L<Locale::Language>.
823 C<Locale::Maketext>, by Sean Burke, is a localization framework. See
824 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
825 article about software localization, originally published in The Perl
826 Journal #13, and republished here with kind permission.
830 C<Math::BigRat> for big rational numbers, to accompany Math::BigInt and
831 Math::BigFloat, from Tels. See L<Math::BigRat>.
835 C<Memoize> can make your functions faster by trading space for time,
836 from Mark-Jason Dominus. See L<Memoize>.
840 C<MIME::Base64>, by Gisle Aas, allows you to encode data in base64,
841 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
846 $encoded = encode_base64('Aladdin:open sesame');
847 $decoded = decode_base64($encoded);
849 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
855 C<MIME::QuotedPrint>, by Gisle Aas, allows you to encode data
856 in quoted-printable encoding, as defined in RFC 2045 - I<MIME
857 (Multipurpose Internet Mail Extensions)>.
859 use MIME::QuotedPrint;
861 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
862 $decoded = decode_qp($encoded);
864 print $encoded, "\n"; # "Smiley in Unicode: =263A"
866 MIME::QuotedPrint has been enhanced to provide the basic methods
867 necessary to use it with PerlIO::Via as in :
869 use MIME::QuotedPrint;
870 open($fh,">Via(MIME::QuotedPrint)",$path);
872 See L<MIME::QuotedPrint>.
876 C<NEXT>, by Damian Conway, is a pseudo-class for method redispatch.
881 C<open> is a new pragma for setting the default I/O disciplines
886 C<PerlIO::Scalar>, by Nick Ing-Simmons, provides the implementation
887 of IO to "in memory" Perl scalars as discussed above. It also serves
888 as an example of a loadable PerlIO layer. Other future possibilities
889 include PerlIO::Array and PerlIO::Code. See L<PerlIO::Scalar>.
893 C<PerlIO::Via>, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
894 PerlIO layer functionality provided by a class (typically implemented
897 use MIME::QuotedPrint;
898 open($fh,">Via(MIME::QuotedPrint)",$path);
900 This will automatically convert everything output to C<$fh>
901 to Quoted-Printable. See L<PerlIO::Via>.
905 C<Pod::ParseLink>, by Russ Allbery, has been added,
906 to parse LZ<><> links in pods as described in the new
911 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
912 It converts POD data to formatted overstrike text.
913 See L<Pod::Text::Overstrike>.
917 C<Scalar::Util> is a selection of general-utility scalar subroutines,
918 such as blessed(), reftype(), and tainted(). See L<Scalar::Util>.
922 C<sort> is a new pragma for controlling the behaviour of sort().
926 C<Storable> gives persistence to Perl data structures by allowing the
927 storage and retrieval of Perl data to and from files in a fast and
928 compact binary format. Because in effect Storable does serialisation
929 of Perl data structues, with it you can also clone deep, hierarchical
930 datastructures. Storable was originally created by Raphael Manfredi,
931 but it is now maintained by Abhijit Menon-Sen. Storable has been
932 enhanced to understand the two new hash features, Unicode keys and
933 restricted hashes. See L<Storable>.
937 C<Switch>, by Damian Conway, has been added. Just by saying
941 you have C<switch> and C<case> available in Perl.
947 case 1 { print "number 1" }
948 case "a" { print "string a" }
949 case [1..10,42] { print "number in list" }
950 case (@array) { print "number in list" }
951 case /\w+/ { print "pattern" }
952 case qr/\w+/ { print "pattern" }
953 case (%hash) { print "entry in hash" }
954 case (\%hash) { print "entry in hash" }
955 case (\&sub) { print "arg to subroutine" }
956 else { print "previous case not true" }
963 C<Test::More>, by Michael Schwern, is yet another framework for writing
964 test scripts, more extensive than Test::Simple. See L<Test::More>.
968 C<Test::Simple>, by Michael Schwern, has basic utilities for writing
969 tests. See L<Test::Simple>.
973 C<Text::Balanced>, by Damian Conway, has been added, for extracting
974 delimited text sequences from strings.
976 use Text::Balanced 'extract_delimited';
978 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
980 $a will be "'never say never'", $b will be ', he never said'.
982 In addition to extract_delimited(), there are also extract_bracketed(),
983 extract_quotelike(), extract_codeblock(), extract_variable(),
984 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
985 gen_extract_tagged(). With these, you can implement rather advanced
986 parsing algorithms. See L<Text::Balanced>.
990 C<threads>, by Arthur Bergman, is an interface to interpreter threads.
991 Interpreter threads (ithreads) is the new thread model introduced in
992 Perl 5.6 but only available as an internal interface for extension
993 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>,
994 L<threads::shared>, and L<perlthrtut>.
998 C<threads::shared>, by Arthur Bergman, allows data sharing for
999 interpreter threads. In the ithreads model any data sharing between
1000 threads must be explicit, as opposed to the old 5.005 thread model
1001 where data sharing was implicit. See L<threads::shared>.
1005 C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
1006 lines of a file. See L<Tie::File>.
1010 C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
1011 See L<Tie::Memoize>.
1015 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
1016 references (unlike the standard Tie::RefHash) The module is contained
1017 within Tie::RefHash. See L<Tie::RefHash>.
1021 C<Time::HiRes>, by Douglas E. Wegscheid, provides high resolution
1022 timing (ualarm, usleep, and gettimeofday). See L<Time::HiRes>.
1026 C<Unicode::UCD> offers a querying interface to the Unicode Character
1027 Database. See L<Unicode::UCD>.
1031 C<Unicode::Collate>, by SADAHIRO Tomoyuki, implements the UCA
1032 (Unicode Collation Algorithm) for sorting Unicode strings.
1033 See L<Unicode::Collate>.
1037 C<Unicode::Normalize>, by SADAHIRO Tomoyuki, implements the various
1038 Unicode normalization forms. See L<Unicode::Normalize>.
1042 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises
1043 XS typemaps. Nothing gets installed, but the code is worth studying
1044 for extension writers.
1048 =head2 Updated And Improved Modules and Pragmata
1054 The following independently supported modules have been updated to the
1055 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
1056 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
1057 (Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
1058 Term::ANSIColor, Test, Text-Tabs+Wrap.
1062 attributes::reftype() now works on tied arguments.
1066 AutoLoader can now be disabled with C<no AutoLoader;>.
1070 B::Deparse has been significantly enhanced by Robin Houston. It now
1071 can deparse almost all of the standard test suite (so that the tests
1072 still succeed). There is a make target "test.deparse" for trying this
1077 Carp has now better interface documentation, and the @CARP_NOT
1078 interface has been added to get optional control over where errors
1079 are reported independently of @ISA, by Ben Tilly.
1083 Class::Struct can now define the classes in compile time.
1087 Class::Struct now assigns the array/hash element if the accessor
1088 is called with an array/hash element as the B<sole> argument.
1092 The return value of Cwd::fastcwd() is now tainted.
1096 Data::Dumper now has an option to sort hashes.
1100 Data::Dumper now has an option to dump code references
1105 DB_File now supports newer Berkeley DB versions, among
1110 Devel::Peek now has an interface for the Perl memory statistics
1111 (this works only if you are using perl's malloc, and if you have
1112 compiled with debugging).
1116 The English module can now be used without the infamous performance
1119 use English '-no_match_vars';
1121 (Assuming, of course, that you don't need the troublesome variables
1122 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1123 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1127 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1128 leads to better portability.
1132 Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clark
1133 to use the new-style constant dispatch section (see L<ExtUtils::Constant>).
1134 This means that they will be more robust and hopefully faster.
1138 File::Find now chdir()s correctly when chasing symbolic links.
1142 File::Find now has pre- and post-processing callbacks. It also
1143 correctly changes directories when chasing symbolic links. Callbacks
1144 (naughtily) exiting with "next;" instead of "return;" now work.
1148 File::Find is now (again) reentrant. It also has been made
1153 The warnings issued by File::Find now belong to their own category.
1154 You can enable/disable them with C<use/no warnings 'File::Find';>.
1158 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1159 prototype mismatch with CORE::glob().
1163 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1164 the returned list of filenames.
1168 IPC::Open3 now allows the use of numeric file descriptors.
1172 IO::Socket now has an atmark() method, which returns true if the socket
1173 is positioned at the out-of-band mark. The method is also exportable
1174 as a sockatmark() function.
1178 IO::Socket::INET has support for the ReusePort option (if your
1179 platform supports it). The Reuse option now has an alias, ReuseAddr.
1180 For clarity, you may want to prefer ReuseAddr.
1184 IO::Socket::INET now supports a value of zero for C<LocalPort>
1185 (usually meaning that the operating system will make one up.)
1189 'use lib' now works identically to @INC. Removing directories
1190 with 'no lib' now works.
1194 Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels.
1195 They are now magnitudes faster, and they support various bignum
1196 libraries such as GMP and PARI as their backends.
1200 Math::Complex handles inf, NaN etc., better.
1204 Net::Ping has been considerably enhanced by Rob Brown: multihoming is
1205 now supported, Win32 functionality is better, there is now time
1206 measuring functionality (optionally high-resolution using
1207 Time::HiRes), and there is now "external" protocol which uses
1208 Net::Ping::External module which runs your external ping utility and
1209 parses the output. A version of Net::Ping::External is available in
1212 Note that some of the Net::Ping tests are disabled when running
1213 under the Perl distribution since one cannot assume one or more
1214 of the following: enabled echo port at localhost, full Internet
1215 connectivity, or sympathetic firewalls. You can set the environment
1216 variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test
1217 suite to enable all the Net::Ping tests.
1221 POSIX::sigaction() is now much more flexible and robust.
1222 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1223 handlers, installing new handlers was not atomic.
1227 In Safe, C<%INC> is now localised in a Safe compartment so that
1232 In SDBM_File on dosish platforms, some keys went missing because of
1233 lack of support for files with "holes". A workaround for the problem
1238 In Search::Dict one can now have a pre-processing hook for the
1239 lines being searched.
1243 The Shell module now has an OO interface.
1247 In Sys::Syslog there is now a failover mechanism that will go
1248 through alternative connection mechanisms until the message
1249 is successfully logged.
1253 The Test module has been significantly enhanced.
1257 Time::Local::timelocal() does not handle fractional seconds anymore.
1258 The rationale is that neither does localtime(), and timelocal() and
1259 localtime() are supposed to be inverses of each other.
1263 The vars pragma now supports declaring fully qualified variables.
1264 (Something that C<our()> does not and will not support.)
1268 The C<utf8::> name space (as in the pragma) provides various
1269 Perl-callable functions to provide low level access to Perl's
1270 internal Unicode representation. At the moment only length()
1271 has been implemented.
1275 =head1 Utility Changes
1281 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1286 F<emacs/e2ctags.pl> is now much faster.
1290 C<enc2xs> is a tool for people adding their own encodings to the
1295 C<h2ph> now supports C trigraphs.
1299 C<h2xs> now produces a template README.
1303 C<h2xs> now uses C<Devel::PPPort> for better portability between
1304 different versions of Perl.
1308 C<h2xs> uses the new L<ExtUtils::Constant|ExtUtils::Constant> module
1309 which will affect newly created extensions that define constants.
1310 Since the new code is more correct (if you have two constants where the
1311 first one is a prefix of the second one, the first constant B<never>
1312 got defined), less lossy (it uses integers for integer constant,
1313 as opposed to the old code that used floating point numbers even for
1314 integer constants), and slightly faster, you might want to consider
1315 regenerating your extension code (the new scheme makes regenerating
1316 easy). L<h2xs> now also supports C trigraphs.
1320 C<libnetcfg> has been added to configure libnet.
1324 C<perlbug> is now much more robust. It also sends the bug report to
1325 perl.org, not perl.com.
1329 C<perlcc> has been rewritten and its user interface (that is,
1330 command line) is much more like that of the UNIX C compiler, cc.
1331 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1332 B<Note that perlcc is still considered very experimental and
1337 C<perlivp> is a new Installation Verification Procedure utility
1338 for running any time after installing Perl.
1342 C<piconv> is an implementation of the character conversion utility
1343 C<iconv>, demonstrating the new Encode module.
1347 C<pod2html> now allows specifying a cache directory.
1351 C<pod2html> now produces XHTML 1.0.
1355 C<pod2html> now understands POD written using different line endings
1356 (PC-like CRLF versus UNIX-like LF versus MacClassic-like CR).
1360 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1361 implementation of sed in Perl: you can use the sed functionality by
1362 using the C<psed> utility.)
1366 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1370 C<xsubpp> now supports the OUT keyword.
1374 =head1 New Documentation
1380 perl56delta details the changes between the 5.005 release and the
1385 perlclib documents the internal replacements for standard C library
1386 functions. (Interesting only for extension writers and Perl core
1391 perldebtut is a Perl debugging tutorial.
1395 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1399 perlintro is a gentle introduction to Perl.
1403 perliol documents the internals of PerlIO with layers.
1407 perlmodstyle is a style guide for writing modules.
1411 perlnewmod tells about writing and submitting a new module.
1415 perlpacktut is a pack() tutorial.
1419 perlpod has been rewritten to be clearer and to record the best
1420 practices gathered over the years.
1424 perlpodspec is a more formal specification of the pod format,
1425 mainly of interest for writers of pod applications, not to
1426 people writing in pod.
1430 perlretut is a regular expression tutorial.
1434 perlrequick is a regular expressions quick-start guide.
1435 Yes, much quicker than perlretut.
1439 perltodo has been updated.
1443 perltootc has been renamed as perltooc (to not to conflict
1444 with perltoot in filesystems restricted to "8.3" names).
1448 perluniintro is an introduction to using Unicode in Perl.
1449 (perlunicode is more of a detailed reference and background
1454 perlutil explains the command line utilities packaged with the Perl
1459 The following platform-specific documents are available before
1460 the installation as README.I<platform>, and after the installation
1463 perlaix perlamiga perlapollo perlbeos perlbs2000
1464 perlce perlcygwin perldgux perldos perlepoc perlhpux
1465 perlhurd perlmachten perlmacos perlmint perlmpeix
1466 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1467 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1469 Eastern Asian Perl users are now welcomed in their own languages:
1470 README.jp (Japanese), README.ko (Korean), README.cn (simplified
1471 Chinese) and README.tw (traditional Chinese), which are written in
1472 normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These
1473 will get installed as
1475 perljp perlko perlcn perltw
1481 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1482 confusion with the Perl POSIX module.
1486 The documentation for the WinCE platform is called perlce (README.ce
1487 in the source code kit), to avoid confusion with the perlwin32
1488 documentation on 8.3-restricted filesystems.
1492 =head1 Performance Enhancements
1498 map() could get pathologically slow when the result list it generates
1499 is larger than the source list. The performance has been improved for
1504 sort() has been changed to use primarily mergesort internally as
1505 opposed to the earlier quicksort. For very small lists this may
1506 result in slightly slower sorting times, but in general the speedup
1507 should be at least 20%. Additional bonuses are that the worst case
1508 behaviour of sort() is now better (in computer science terms it now
1509 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1510 worst-case run time behaviour), and that sort() is now stable
1511 (meaning that elements with identical keys will stay ordered as they
1512 were before the sort). See the C<sort> pragma for information.
1514 The story in more detail: suppose you want to serve yourself a little
1517 @digits = ( 3,1,4,1,5,9 );
1519 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1520 Which C<1> comes first is hard to know, since one C<1> looks pretty
1521 much like any other. You can regard this as totally trivial,
1522 or somewhat profound. However, if you just want to sort the even
1523 digits ahead of the odd ones, then what will
1525 sort { ($a % 2) <=> ($b % 2) } @digits;
1527 yield? The only even digit, C<4>, will come first. But how about
1528 the odd numbers, which all compare equal? With the quicksort algorithm
1529 used to implement Perl 5.6 and earlier, the order of ties is left up
1530 to the sort. So, as you add more and more digits of Pi, the order
1531 in which the sorted even and odd digits appear will change.
1532 and, for sufficiently large slices of Pi, the quicksort algorithm
1533 in Perl 5.8 won't return the same results even if reinvoked with the
1534 same input. The justification for this rests with quicksort's
1535 worst case behavior. If you run
1537 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1539 (something you might approximate if you wanted to merge two sorted
1540 arrays using sort), doubling $N doesn't just double the quicksort time,
1541 it I<quadruples> it. Quicksort has a worst case run time that can
1542 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1543 on patterns that may well arise in normal use. You won't notice this
1544 for small arrays, but you I<will> notice it with larger arrays,
1545 and you may not live long enough for the sort to complete on arrays
1546 of a million elements. So the 5.8 quicksort scrambles large arrays
1547 before sorting them, as a statistical defence against quadratic behaviour.
1548 But that means if you sort the same large array twice, ties may be
1549 broken in different ways.
1551 Because of the unpredictability of tie-breaking order, and the quadratic
1552 worst-case behaviour, quicksort was I<almost> replaced completely with
1553 a stable mergesort. I<Stable> means that ties are broken to preserve
1554 the original order of appearance in the input array. So
1556 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1558 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1559 appear in the output in the same order they appeared in the input.
1560 Mergesort has worst case O(N log N) behaviour, the best value
1561 attainable. And, ironically, this mergesort does particularly
1562 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1563 in O(N) time. But quicksort was rescued at the last moment because
1564 it is faster than mergesort on certain inputs and platforms.
1565 For example, if you really I<don't> care about the order of even
1566 and odd digits, quicksort will run in O(N) time; it's very good
1567 at sorting many repetitions of a small number of distinct elements.
1568 The quicksort divide and conquer strategy works well on platforms
1569 with relatively small, very fast, caches. Eventually, the problem gets
1570 whittled down to one that fits in the cache, from which point it
1571 benefits from the increased memory speed.
1573 Quicksort was rescued by implementing a sort pragma to control aspects
1574 of the sort. The B<stable> subpragma forces stable behaviour,
1575 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1576 subpragmas are heavy-handed ways to select the underlying implementation.
1577 The leading C<_> is a reminder that these subpragmas may not survive
1578 beyond 5.8. More appropriate mechanisms for selecting the implementation
1579 exist, but they wouldn't have arrived in time to save quicksort.
1583 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1584 ( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is
1585 reasonably fast while producing a much better spread of values than
1586 the old hashing algorithm (originally by Chris Torek, later tweaked by
1587 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1588 all 3-char printable ASCII keys comes much closer to passing the
1589 DIEHARD random number generation tests. According to perlbench, this
1590 change has not affected the overall speed of Perl.
1594 unshift() should now be noticeably faster.
1598 =head1 Installation and Configuration Improvements
1600 =head2 Generic Improvements
1606 INSTALL now explains how you can configure Perl to use 64-bit
1607 integers even on non-64-bit platforms.
1611 Policy.sh policy change: if you are reusing a Policy.sh file
1612 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1613 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1614 them will now be changed to the new prefix, /foo/bar. (Previously
1615 only $prefix changed.) If you do not like this new behaviour,
1616 specify prefix, siteprefix, and vendorprefix explicitly.
1620 A new optional location for Perl libraries, otherlibdirs, is available.
1621 It can be used for example for vendor add-ons without disturbing Perl's
1622 own library directories.
1626 In many platforms, the vendor-supplied 'cc' is too stripped-down to
1627 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1628 to be the case and 'cc' does not seem to be the GNU C compiler
1629 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1633 gcc needs to closely track the operating system release to avoid
1634 build problems. If Configure finds that gcc was built for a different
1635 operating system release than is running, it now gives a clearly visible
1636 warning that there may be trouble ahead.
1640 Since Perl 5.8 is not binary-compatible with previous releases
1641 of Perl, Configure no longer suggests including the 5.005
1646 Configure C<-S> can now run non-interactively.
1650 Configure support for pdp11-style memory models has been removed due
1655 configure.gnu now works with options with whitespace in them.
1659 installperl now outputs everything to STDERR.
1663 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1664 get appended to the $Config{archname} (also known as $^O) anymore.
1665 Instead, if you explicitly choose not to use perlio (Configure command
1666 line option -Uuseperlio), you will get "-stdio" appended.
1670 Another change related to the architecture name is that "-64all"
1671 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1672 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1676 In AFS installations, one can configure the root of the AFS to be
1677 somewhere else than the default F</afs> by using the Configure
1678 parameter C<-Dafsroot=/some/where/else>.
1682 APPLLIB_EXP, a lesser-known configuration-time definition, has been
1683 documented. It can be used to prepend site-specific directories
1684 to Perl's default search path (@INC); see INSTALL for information.
1688 The version of Berkeley DB used when the Perl (and, presumably, the
1689 DB_File extension) was built is now available as
1690 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1691 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1692 DB_VERSION_PATCH_CFG> from C.
1696 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1697 has been documented in INSTALL.
1701 If you have CPAN access (either network or a local copy such as a
1702 CD-ROM) you can during specify extra modules to Configure to build and
1703 install with Perl using the -Dextras=... option. See INSTALL for
1708 In addition to config.over, a new override file, config.arch, is
1709 available. This file is supposed to be used by hints file writers
1710 for architecture-wide changes (as opposed to config.over which is
1711 for site-wide changes).
1715 If your file system supports symbolic links, you can build Perl outside
1716 of the source directory by
1718 mkdir /tmp/perl/build/directory
1719 cd /tmp/perl/build/directory
1720 sh /path/to/perl/source/Configure -Dmksymlinks ...
1722 This will create in /tmp/perl/build/directory a tree of symbolic links
1723 pointing to files in /path/to/perl/source. The original files are left
1724 unaffected. After Configure has finished, you can just say
1728 and Perl will be built and tested, all in /tmp/perl/build/directory.
1732 For Perl developers, several new make targets for profiling
1733 and debugging have been added; see L<perlhack>.
1739 Use of the F<gprof> tool to profile Perl has been documented in
1740 L<perlhack>. There is a make target called "perl.gprof" for
1741 generating a gprofiled Perl executable.
1745 If you have GCC 3, there is a make target called "perl.gcov" for
1746 creating a gcoved Perl executable for coverage analysis. See
1751 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1752 have been added; see L<perlhack> for more information about pixie and
1759 Guidelines of how to construct minimal Perl installations have
1760 been added to INSTALL.
1764 The Thread extension is now not built at all under ithreads
1765 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1766 Thread extension requires being Configured with C<-Duse5005threads>).
1768 But note that the Thread.pm interface is now shared by both
1773 The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
1774 floating-point numbers is now more picky about using sprintf %.*g
1775 rules for the conversion. Some platforms that used to use gcvt may
1776 now resort to the slower sprintf.
1780 The obsolete method of making a special (e.g., debugging) flavor
1783 make LIBPERL=libperld.a
1785 has been removed. Use -DDEBUGGING instead.
1789 =head2 New Or Improved Platforms
1791 For the list of platforms known to support Perl,
1792 see L<perlport/"Supported Platforms">.
1798 AIX dynamic loading should be now better supported.
1802 AIX should now work better with gcc, threads, and 64-bitness. Also the
1803 long doubles support in AIX should be better now. See L<perlaix>.
1807 AtheOS ( http://www.atheos.cx/ ) is a new platform.
1811 BeOS has been reclaimed.
1815 The DG/UX platform now supports 5.005-style threads.
1820 The DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near
1825 EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA)
1826 have been regained. Many test suite tests still fail and the
1827 co-existence of Unicode and EBCDIC isn't quite settled, but the
1828 situation is much better than with Perl 5.6. See L<perlos390>,
1829 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1833 Building perl with -Duseithreads or -Duse5005threads now works under
1834 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1835 need a thread library package installed. See README.hpux.
1839 MacOS Classic (MacPerl has of course been available since
1840 perl 5.004 but now the source code bases of standard Perl
1841 and MacPerl have been synchronised)
1845 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1846 filesystems. (The case-insensitivity used to confuse the Perl build
1851 NCR MP-RAS is now supported.
1855 All the NetBSD specific patches (except for the installation
1856 specific ones) have been merged back to the main distribution.
1860 NetWare from Novell is now supported. See L<perlnetware>.
1864 NonStop-UX is now supported.
1868 NEC SUPER-UX is now supported.
1872 All the OpenBSD specific patches (except for the installation
1873 specific ones) have been merged back to the main distribution.
1877 Perl has been tested with the GNU pth userlevel thread package
1878 ( http://www.gnu.org/software/pth/pth.html ) . All but one thread
1879 test worked, and that one failure was because of test results arriving
1880 in unexpected order.
1884 Stratus VOS is now supported using Perl's native build method
1885 (Configure). This is the recommended method to build Perl on
1886 VOS. The older methods, which build miniperl, are still
1887 available. See L<perlvos>.
1891 The Amdahl UTS UNIX mainframe platform is now supported.
1895 WinCE is now supported. See L<perlce>.
1899 z/OS (formerly known as OS/390, formerly known as MVS OE) now has
1900 support for dynamic loading. This is not selected by default,
1901 however, you must specify -Dusedl in the arguments of Configure.
1905 =head1 Selected Bug Fixes
1907 Numerous memory leaks and uninitialized memory accesses have been
1908 hunted down. Most importantly, anonymous subs used to leak quite
1915 The autouse pragma didn't work for Multi::Part::Function::Names.
1919 caller() could cause core dumps in certain situations. Carp was sometimes
1920 affected by this problem. In particular, caller() now returns a
1921 subroutine name of C<(unknown)> for subroutines that have been removed
1922 from the symbol table.
1926 chop(@list) in list context returned the characters chopped in
1927 reverse order. This has been reversed to be in the right order.
1931 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1932 when building the Perl binary. The only exception to this is SunOS 4.x,
1937 The behaviour of non-decimal but numeric string constants such as
1938 "0x23" was platform-dependent: in some platforms that was seen as 35,
1939 in some as 0, in some as a floating point number (don't ask). This
1940 was caused by Perl's using the operating system libraries in a situation
1941 where the result of the string to number conversion is undefined: now
1942 Perl consistently handles such strings as zero in numeric contexts.
1946 The order of DESTROYs has been made more predictable.
1950 Several debugger fixes: exit code now reflects the script exit code,
1951 condition C<"0"> now treated correctly, the C<d> command now checks
1952 line number, C<$.> no longer gets corrupted, and all debugger output
1953 now goes correctly to the socket if RemotePort is set.
1957 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1958 when statically building extensions into perl. This has been corrected.
1962 L<dprofpp> -R didn't work.
1966 C<*foo{FORMAT}> now works.
1970 Infinity is now recognized as a number.
1974 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1975 the Tk extension with 5.6.0.)
1979 Lexicals I: lexicals outside an eval "" weren't resolved
1980 correctly inside a subroutine definition inside the eval "" if they
1981 were not already referenced in the top level of the eval""ed code.
1985 Lexicals II: lexicals leaked at file scope into subroutines that
1986 were declared before the lexicals.
1990 Lexical warnings now propagating correctly between scopes
1991 and into C<eval "...">.
1995 C<use warnings qw(FATAL all)> did not work as intended. This has been
2000 warnings::enabled() now reports the state of $^W correctly if the caller
2001 isn't using lexical warnings.
2005 Line renumbering with eval and C<#line> now works.
2009 Fixed numerous memory leaks, especially in eval "".
2013 Localised tied variables no longer leak memory
2016 tie my %tied_hash => 'Tie::StdHash';
2020 # Used to leak memory every time local() was called;
2021 # in a loop, this added up.
2022 local($tied_hash{Foo}) = 1;
2026 Localised hash elements (and %ENV) are correctly unlocalised to not
2027 exist, if they didn't before they were localised.
2031 tie my %tied_hash => 'Tie::StdHash';
2035 # Nothing has set the FOO element so far
2037 { local $tied_hash{FOO} = 'Bar' }
2039 # This used to print, but not now.
2040 print "exists!\n" if exists $tied_hash{FOO};
2042 As a side effect of this fix, tied hash interfaces B<must> define
2043 the EXISTS and DELETE methods.
2047 mkdir() now ignores trailing slashes in the directory name,
2048 as mandated by POSIX.
2052 Some versions of glibc have a broken modfl(). This affects builds
2053 with C<-Duselongdouble>. This version of Perl detects this brokenness
2054 and has a workaround for it. The glibc release 2.2.2 is known to have
2055 fixed the modfl() bug.
2059 Modulus of unsigned numbers now works (4063328477 % 65535 used to
2060 return 27406, instead of 27047).
2064 Some "not a number" warnings introduced in 5.6.0 eliminated to be
2065 more compatible with 5.005. Infinity is now recognised as a number.
2069 Numeric conversions did not recognize changes in the string value
2070 properly in certain circumstances.
2074 Attributes (such as :shared) didn't work with our().
2078 our() variables will not cause "will not stay shared" warnings.
2082 "our" variables of the same name declared in two sibling blocks
2083 resulted in bogus warnings about "redeclaration" of the variables.
2084 The problem has been corrected.
2088 pack "Z" now correctly terminates the string with "\0".
2092 Fix password routines which in some shadow password platforms
2093 (e.g. HP-UX) caused getpwent() to return every other entry.
2097 The PERL5OPT environment variable (for passing command line arguments
2098 to Perl) didn't work for more than a single group of options.
2102 PERL5OPT with embedded spaces didn't work.
2106 printf() no longer resets the numeric locale to "C".
2110 C<qw(a\\b)> now parses correctly as C<'a\\b'>: that is, as three
2111 characters, not four.
2115 pos() did not return the correct value within s///ge in earlier
2116 versions. This is now handled correctly.
2120 Printing quads (64-bit integers) with printf/sprintf now works
2121 without the q L ll prefixes (assuming you are on a quad-capable platform).
2125 Regular expressions on references and overloaded scalars now work.
2129 Right-hand side magic (GMAGIC) could in many cases such as string
2130 concatenation be invoked too many times.
2134 scalar() now forces scalar context even when used in void context.
2138 SOCKS support is now much more robust.
2142 sort() arguments are now compiled in the right wantarray context
2143 (they were accidentally using the context of the sort() itself).
2144 The comparison block is now run in scalar context, and the arguments
2145 to be sorted are always provided list context.
2149 Changed the POSIX character class C<[[:space:]]> to include the (very
2150 rarely used) vertical tab character. Added a new POSIX-ish character
2151 class C<[[:blank:]]> which stands for horizontal whitespace
2152 (currently, the space and the tab).
2156 The tainting behaviour of sprintf() has been rationalized. It does
2157 not taint the result of floating point formats anymore, making the
2158 behaviour consistent with that of string interpolation.
2162 Some cases of inconsistent taint propagation (such as within hash
2163 values) have been fixed.
2167 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
2168 of simple pattern matches. These are now handled better.
2172 Regular expression debug output (whether through C<use re 'debug'>
2173 or via C<-Dr>) now looks better.
2177 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
2182 Use of $& could trigger a core dump under some situations. This
2187 The regular expression captured submatches ($1, $2, ...) are now
2188 more consistently unset if the match fails, instead of leaving false
2189 data lying around in them.
2193 readline() on files opened in "slurp" mode could return an extra
2194 "" (blank line) at the end in certain situations. This has been
2199 Autovivification of symbolic references of special variables described
2200 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
2205 Sys::Syslog ignored the C<LOG_AUTH> constant.
2209 All but the first argument of the IO syswrite() method are now optional.
2213 $AUTOLOAD, sort(), lock(), and spawning subprocesses
2214 in multiple threads simultaneously are now thread-safe.
2218 Tie::Array's SPLICE method was broken.
2222 Allow a read-only string on the left-hand side of a non-modifying tr///.
2226 If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
2227 correctly pass to it.
2231 Several Unicode fixes.
2237 BOMs (byte order marks) at the beginning of Perl files
2238 (scripts, modules) should now be transparently skipped.
2239 UTF-16 and UCS-2 encoded Perl files should now be read correctly.
2243 The character tables have been updated to Unicode 3.2.0.
2247 Comparing with utf8 data does not magically upgrade non-utf8 data
2248 into utf8. (This was a problem for example if you were mixing data
2249 from I/O and Unicode data: your output might have got magically encoded
2254 Generating illegal Unicode code points such as U+FFFE, or the UTF-16
2255 surrogates, now also generates an optional warning.
2259 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2263 Concatenation with the C<.> operator or via variable interpolation,
2264 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2265 substitution with C<s///>, single-quoted UTF8, should now work.
2269 The C<tr///> operator now works. Note that the C<tr///CU>
2270 functionality has been removed (but see pack('U0', ...)).
2274 C<eval "v200"> now works.
2278 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2279 This has been corrected.
2283 Zero entries were missing from the Unicode classes such as C<IsDigit>.
2289 Large unsigned numbers (those above 2**31) could sometimes lose their
2290 unsignedness, causing bogus results in arithmetic operations.
2294 The Perl parser has been stress tested using both random input and
2295 Markov chain input and the few found crashes and lockups have been
2300 =head2 Platform Specific Changes and Fixes
2308 Perl now works on post-4.0 BSD/OSes.
2314 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2320 Numerous updates; currently synchronised with Cygwin 1.3.10.
2324 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2330 EPOC update after Perl 5.6.0. See README.epoc.
2336 Perl now works on post-3.0 FreeBSDs.
2342 README.hpux updated; C<Configure -Duse64bitall> now works;
2343 now uses HP-UX malloc instead of Perl malloc.
2349 Numerous compilation flag and hint enhancements; accidental mixing
2350 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2360 Long doubles should now work (see INSTALL).
2364 Linux previously had problems related to sockaddrlen when using
2365 accept(), recvfrom() (in Perl: recv()), getpeername(), and
2374 Compilation of the standard Perl distribution in MacOS Classic should
2375 now work if you have the Metrowerks development environment and
2376 the missing Mac-specific toolkit bits. Contact the macperl mailing
2383 MPE/iX update after Perl 5.6.0. See README.mpeix.
2387 NetBSD/threads: try installing the GNU pth (should be in the
2388 packages collection, or http://www.gnu.org/software/pth/),
2389 and Configure with -Duseithreads.
2395 Perl now works on NetBSD/sparc.
2401 Now works with usethreads (see INSTALL).
2407 64-bitness using the Sun Workshop compiler now works.
2413 The native build method requires at least VOS Release 14.5.0
2414 and GNU C++/GNU Tools 2.0.1 or later. The Perl pack function
2415 now maps overflowed values to +infinity and underflowed values
2420 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2422 The operating system version letter now recorded in $Config{osvers}.
2423 Allow compiling with gcc (previously explicitly forbidden). Compiling
2424 with gcc still not recommended because buggy code results, even with
2431 Fixed various alignment problems that lead into core dumps either
2432 during build or later; no longer dies on math errors at runtime;
2433 now using full quad integers (64 bits), previously was using
2434 only 46 bit integers for speed.
2440 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2441 (see INSTALL); now works with Perl's malloc.
2443 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2444 unimplemented. It now works as documented.
2446 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2447 was that a pid of -1 would cause a wildcard search of all processes on
2450 POSIX-style signals are now emulated much better on VMS versions prior
2453 The C<system> function and backticks operator have improved
2454 functionality and better error handling.
2456 File access tests now use current process privileges rather than the
2457 user's default privileges, which could sometimes result in a mismatch
2458 between reported access and actual access.
2460 There is a new C<kill> implementation based on C<sys$sigprc> that allows
2461 older VMS systems (pre-7.0) to use C<kill> to send signals rather than
2462 simply force exit. This implementation also allows later systems to
2463 call C<kill> from within a signal handler.
2465 Iterative logical name translations are now limited to 10 iterations in
2466 imitation of SHOW LOGICAL and other OpenVMS facilities.
2476 accept() no longer leaks memory.
2480 Borland C++ v5.5 is now a supported compiler that can build Perl.
2481 However, the generated binaries continue to be incompatible with those
2482 generated by the other supported compilers (GCC and Visual C++).
2486 Better chdir() return value for a non-existent directory.
2490 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2494 New %ENV entries now propagate to subprocesses.
2498 Current directory entries in %ENV are now correctly propagated to child
2503 $ENV{LIB} now used to search for libs under Visual C.
2507 fork() emulation has been improved in various ways, but still continues
2508 to be experimental. See L<perlfork> for known bugs and caveats.
2512 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2516 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2517 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2521 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2525 The makefiles now provide a single switch to bulk-enable all the features
2526 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2530 Allow REG_EXPAND_SZ keys in the registry.
2534 Can now send() from all threads, not just the first one.
2538 Fake signal handling reenabled, bugs and all.
2542 %SIG has been enabled under USE_ITHREADS, but its use is completely
2543 unsupported under all configurations.
2547 Less stack reserved per thread so that more threads can run
2548 concurrently. (Still 16M per thread.)
2552 C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
2553 (works better when perl is running as service).
2557 Better UNC path handling under ithreads.
2561 wait(), waitpid(), and backticks now return the correct exit status
2566 Win64 compilation is now supported.
2570 winsock handle leak fixed.
2576 =head1 New or Changed Diagnostics
2582 The lexical warnings category "deprecated" is no longer a sub-category
2583 of the "syntax" category. It is now a top-level category in its own
2588 All regular expression compilation error messages are now hopefully
2589 easier to understand both because the error message now comes before
2590 the failed regex and because the point of failure is now clearly
2591 marked by a C<E<lt>-- HERE> marker.
2595 The various "opened only for", "on closed", "never opened" warnings
2596 drop the C<main::> prefix for filehandles in the C<main> package,
2597 for example C<STDIN> instead of C<main::STDIN>.
2601 The "Unrecognized escape" warning has been extended to include C<\8>,
2602 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2606 Two new debugging options have been added: if you have compiled your
2607 Perl with debugging, you can use the -DT and -DR options to trace
2608 tokenising and to add reference counts to displaying variables,
2613 The debugger (perl5db.pl) has been modified to present a more
2614 consistent commands interface, via (CommandSet=580). perl5db.t was
2615 also added to test the changes, and as a placeholder for further tests.
2621 The debugger has a new C<dumpDepth> option to control the maximum
2622 depth to which nested structures are dumped. The C<x> command has
2623 been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a
2624 depth of at most I<N> levels.
2628 The debugger can now show lexical variables if you have the CPAN
2629 module PadWalker installed.
2633 If an attempt to use a (non-blessed) reference as an array index
2634 is made, a warning is given.
2638 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2639 now give a warning. This may be a problem for generated and evaled
2644 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2645 using the C<"C"> format you will get an optional warning. Similarly
2646 for the C<"c"> format and a number less than -128 or more than 127.
2650 Certain regex modifiers such as C<(?o)> make sense only if applied to
2651 the entire regex. You will get an optional warning if you try to do
2656 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2657 has been deprecated for a while. Now you will get an optional warning.
2661 Using C<sort> in scalar context now issues an optional warning.
2662 This didn't do anything useful, as the sort was not performed.
2666 =head1 Changed Internals
2672 perlapi.pod (a companion to perlguts) now attempts to document the
2677 You can now build a really minimal perl called microperl.
2678 Building microperl does not require even running Configure;
2679 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2680 many assumptions, some of which may be too bold; the resulting
2681 executable may crash or otherwise misbehave in wondrous ways.
2682 For careful hackers only.
2686 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2687 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2688 interfaces to the publicised API. For the full list of the available
2689 APIs see L<perlapi>.
2693 Made possible to propagate customised exceptions via croak()ing.
2697 Now xsubs can have attributes just like subs. (Well, at least the
2698 built-in attributes.)
2702 dTHR and djSP have been obsoleted; the former removed (because it's
2703 a no-op) and the latter replaced with dSP.
2707 PERL_OBJECT has been completely removed.
2711 The MAGIC constants (e.g. C<'P'>) have been macrofied
2712 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2713 and maintainability.
2717 The regex compiler now maintains a structure that identifies nodes in
2718 the compiled bytecode with the corresponding syntactic features of the
2719 original regex expression. The information is attached to the new
2720 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2721 complete information.
2725 The C code has been made much more C<gcc -Wall> clean. Some warning
2726 messages still remain in some platforms, so if you are compiling with
2727 gcc you may see some warnings about dubious practices. The warnings
2728 are being worked on.
2732 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2736 Documentation on how to use the Perl source repository has been added
2737 to F<Porting/repository.pod>.
2741 There are now several profiling make targets.
2745 =head1 Security Vulnerability Closed
2747 (This change was already made in 5.7.0 but bears repeating here.)
2749 A potential security vulnerability in the optional suidperl component
2750 of Perl was identified in August 2000. suidperl is neither built nor
2751 installed by default. As of November 2001 the only known vulnerable
2752 platform is Linux, most likely all Linux distributions. CERT and
2753 various vendors and distributors have been alerted about the vulnerability.
2754 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2755 for more information.
2757 The problem was caused by Perl trying to report a suspected security
2758 exploit attempt using an external program, /bin/mail. On Linux
2759 platforms the /bin/mail program had an undocumented feature which
2760 when combined with suidperl gave access to a root shell, resulting in
2761 a serious compromise instead of reporting the exploit attempt. If you
2762 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2763 suidperl is not installed, you are safe.
2765 The exploit attempt reporting feature has been completely removed from
2766 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2767 from all the Perl 5.7 releases), so that particular vulnerability
2768 isn't there anymore. However, further security vulnerabilities are,
2769 unfortunately, always possible. The suidperl functionality is most
2770 probably going to be removed in Perl 5.10. In any case, suidperl
2771 should only be used by security experts who know exactly what they are
2772 doing and why they are using suidperl instead of some other solution
2773 such as sudo ( see http://www.courtesan.com/sudo/ ).
2777 Several new tests have been added, especially for the F<lib> and F<ext>
2778 subsections. There are now about 65 000 individual tests (spread over
2779 about 700 test scripts), in the regression suite (5.6.1 has about
2780 11700 tests, in 258 test scripts) Many of the new tests are of course
2781 introduced by the new modules, but still in general Perl is now more
2784 Because of the large number of tests, running the regression suite
2785 will take considerably longer time than it used to: expect the suite
2786 to take up to 4-5 times longer to run than in perl 5.6. On a really
2787 fast machine you can hope to finish the suite in about 6-8 minutes
2790 The tests are now reported in a different order than in earlier Perls.
2791 (This happens because the test scripts from under t/lib have been moved
2792 to be closer to the library/extension they are testing.)
2794 =head1 Known Problems
2802 If using the AIX native make command, instead of just "make" issue
2803 "make all". In some setups the former has been known to spuriously
2804 also try to run "make install". Alternatively, you may want to use
2809 In AIX 4.2, Perl extensions that use C++ functions that use statics
2810 may have problems in that the statics are not getting initialized.
2811 In newer AIX releases, this has been solved by linking Perl with
2812 the libC_r library, but unfortunately in AIX 4.2 the said library
2813 has an obscure bug where the various functions related to time
2814 (such as time() and gettimeofday()) return broken values, and
2815 therefore in AIX 4.2 Perl is not linked against libC_r.
2819 vac 5.0.0.0 May Produce Buggy Code For Perl
2821 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2822 resulting in a few random tests failing when run as part of "make
2823 test", but when the failing tests are run by hand, they succeed.
2824 We suggest upgrading to at least vac version 5.0.1.0, that has been
2825 known to compile Perl correctly. "lslpp -L|grep vac.C" will tell
2826 you the vac version. See README.aix.
2830 If building threaded Perl, you may get compilation warning from pp_sys.c:
2832 "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
2834 This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()
2835 having slightly different types for their first argument.
2839 =head2 Alpha systems with old gccs fail several tests
2841 If you see op/pack, op/pat, op/regexp, or ext/Storable tests failing
2842 in a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc.
2843 gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 may
2844 be even better. (RedHat Linux/alpha with gcc 3.1 reported no problems,
2845 as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable to
2846 use the bundled C compiler.)
2850 Perl 5.8.0 doesn't build in AmigaOS. It broke at some point
2851 during the ithreads work and we could not find Amiga experts
2852 to unbreak the problems.
2856 The following tests fail on 5.8.0 Perl in BeOS Personal 5.03:
2858 t/op/lfs............................FAILED at test 17
2859 t/op/magic..........................FAILED at test 24
2860 ext/POSIX/t/sigaction...............FAILED at test 13
2861 ext/POSIX/t/waitpid.................FAILED at test 1
2863 See L<perlbeos> (README.beos) for more details.
2865 =head2 Cygwin "unable to remap"
2867 For example when building the Tk extension for Cygwin,
2868 you may get an error message saying "unable to remap".
2869 This is known problem with Cygwin, and a workaround is
2870 detailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html
2872 =head2 ext/threads/t/libc
2874 If this test fails, it indicates that your libc (C library) is not
2875 threadsafe. This particular test stress tests the localtime() call to
2876 find out whether it is threadsafe. See L<perlthrtut> for more information.
2878 =head2 FreeBSD Failing locale Test 117 For ISO8859-15 Locales
2880 The ISO8859-15 locales may fail the locale test 117 in FreeBSD.
2881 This is caused by the characters \xFF (y with diaeresis) and \xBE
2882 (Y with diaeresis) not behaving correctly when being matched
2885 =head2 IRIX fails ext/List/Util/t/shuffle.t
2887 IRIX with MIPSpro 7.3.1.3m compiler may fail the said List::Util test
2888 by dumping core. This seems to be a compiler error since if compiled
2889 with gcc no core dump ensues, and no failures on the said test on any
2892 =head2 Modifying $_ Inside for(..)
2896 works without complaint. It shouldn't. (You should be able to
2897 modify only lvalue elements inside the loops.) You can see the
2898 correct behaviour by replacing the 1..5 with 1, 2, 3, 4, 5.
2900 =head2 mod_perl 1.26 Doesn't Build With Threaded Perl
2902 Use mod_perl 1.27 or higher.
2904 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2906 Don't panic. Read the 'make test' section of INSTALL instead.
2908 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2910 If perl is configured with -Duse64bitall, the successful result of the
2911 subtest 10 of lib/posix may arrive before the successful result of the
2912 subtest 9, which confuses the test harness so much that it thinks the
2915 =head2 Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint
2917 This is a known bug in the glibc 2.2.5 with long long integers.
2918 ( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )
2920 =head2 Linux With Sfio Fails op/misc Test 48
2924 =head2 libwww-perl (LWP) fails base/date #51
2926 Use libwww-perl 5.65 or later.
2930 Please remember to set your environment variable LC_ALL to "C"
2931 (setenv LC_ALL C) before running "make test" to avoid a lot of
2932 warnings about the broken locales of Mac OS X.
2934 The following tests are known to fail in Mac OS X 10.1.4 because of
2935 buggy (old) implementations of Berkeley DB included in Mac OS X:
2937 Failed Test Stat Wstat Total Fail Failed List of Failed
2938 -------------------------------------------------------------------------
2939 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2940 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2942 If you are building on a UFS partition, you will also probably see
2943 t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not
2944 supporting inode change time.
2946 Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped for
2947 now because the failure is Apple's fault, not Perl's (blocked signals
2950 If you Configure with ithreads, ext/threads/t/libc.t will fail. Again,
2951 this is not Perl's fault-- the libc of Mac OS X is not threadsafe
2952 (in this particular test, the localtime() call is found to be
2955 =head2 op/sprintf tests 91, 129, and 130
2957 The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.
2958 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2960 Test 91 is known to fail on QNX6 (nto), because C<sprintf '%e',0>
2961 incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>.
2963 For tests 129 and 130, the failing platforms do not comply with
2964 the ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, to
2965 be exact. (They produce something other than "1" and "-1" when
2966 formatting 0.6 and -0.6 using the printf format "%.0f"; most often,
2967 they produce "0" and "-0".)
2971 In case you are still using Solaris 2.5 (aka SunOS 5.5), you may
2972 experience failures (the test core dumping) in lib/locale.t.
2973 The suggested cure is to upgrade your Solaris.
2977 When Perl is built using the native build process on VOS Release
2978 14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests either
2979 pass or result in TODO (ignored) failures.
2981 =head2 Term::ReadKey not working on Win32
2983 Use Term::ReadKey 2.20 or later.
2985 =head2 Failure of Thread (5.005-style) tests
2987 B<Note that support for 5.005-style threading is deprecated,
2988 experimental and practically unsupported. In 5.10, it is expected
2991 The following tests are known to fail due to fundamental problems in
2992 the 5.005 threading implementation. These are not new failures--Perl
2993 5.005_0x has the same bugs, but didn't have these tests.
2995 ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7
2996 ../lib/English.t 2 512 54 2 3.70% 2-3
2997 ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3
2998 ../lib/Filter/Simple/t/filter_only 9 3 33.33% 1-2 5
2999 ../lib/autouse.t 10 1 10.00% 4
3000 op/flip.t 15 1 6.67% 15
3002 These failures are unlikely to get fixed as 5.005-style threads
3003 are considered fundamentally broken. (Basically what happens is that
3004 competing threads can corrupt shared global state.)
3006 =head2 Timing problems
3008 The following tests may fail intermittently because of timing
3009 problems, for example if the system is heavily loaded.
3012 ext/Time/HiRes/HiRes.t
3014 lib/Memoize/t/expmod_t.t
3015 lib/Memoize/t/speed.t
3017 In case of failure please try running them manually, for example
3019 ./perl -Ilib ext/Time/HiRes/HiRes.t
3023 ../lib/Math/Trig.t 26 1 3.85% 25
3024 ../lib/warnings.t 470 1 0.21% 429
3026 The Trig.t failure is caused by the slighly differing (from IEEE)
3027 floating point implementation of UNICOS. The warnings.t failure is
3028 also related: the test assumes a certain floating point output format;
3029 this assumption fails in UNICOS.
3037 During Configure, the test
3039 Guessing which symbols your C compiler and preprocessor define...
3041 will probably fail with error messages like
3043 CC-20 cc: ERROR File = try.c, Line = 3
3044 The identifier "bad" is undefined.
3046 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
3049 CC-65 cc: ERROR File = try.c, Line = 3
3050 A semicolon is expected at this point.
3052 This is caused by a bug in the awk utility of UNICOS/mk. You can ignore
3053 the error, but it does cause a slight problem: you cannot fully
3054 benefit from the h2ph utility (see L<h2ph>) that can be used to
3055 convert C headers to Perl libraries, mainly used to be able to access
3056 from Perl the constants defined using C preprocessor, cpp. Because of
3057 the above error, parts of the converted headers will be invisible.
3058 Luckily, these days the need for h2ph is rare.
3062 If building Perl with interpreter threads (ithreads), the
3063 getgrent(), getgrnam(), and getgrgid() functions cannot return the
3064 list of the group members due to a bug in the multithreaded support of
3065 UNICOS/mk. What this means is that in list context the functions will
3066 return only three values, not four.
3072 There are a few known test failures, see L<perluts> (README.uts).
3076 There should be no reported test failures with a default configuration,
3077 though there are a number of tests marked TODO that point to areas
3078 needing further debugging and/or porting work.
3082 In multi-CPU boxes, there are some problems with the I/O buffering:
3083 some output may appear twice.
3085 =head2 XML::Parser not working
3087 Use XML::Parser 2.31 or later.
3089 =head2 z/OS (OS/390)
3091 z/OS has rather many test failures but the situation is actually
3092 better than it was in 5.6.0; it's just that so many new modules and
3093 tests have been added.
3095 Failed Test Stat Wstat Total Fail Failed List of Failed
3096 ---------------------------------------------------------------------------
3097 ../ext/Data/Dumper/t/dumper.t 357 8 2.24% 311 314 325 327
3099 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5
3100 ../ext/Storable/t/downgrade.t 12 3072 169 12 7.10% 14-15 46-47 78-79
3102 ../lib/ExtUtils/t/Constant.t 121 30976 48 48 100.00% 1-48
3103 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9
3104 op/pat.t 910 7 0.77% 665 776 785 832-
3106 op/sprintf.t 224 3 1.34% 98 100 136
3107 op/tr.t 97 5 5.15% 63 71-74
3108 uni/fold.t 780 6 0.77% 61 169 196 661
3111 The failures in dumper.t and downgrade.t are problems in the tests,
3112 those in io_unix and sprintf are problems in the USS (UDP sockets
3113 and printf formats). The pat, tr, and fold failures are genuine Perl
3114 problems caused by EBCDIC (and in the pat and fold cases, combining
3115 that with Unicode). The Constant and Embed are probably problems
3116 in the tests (since they test Perl's ability to build extensions,
3117 and that seems to be working reasonably well.)
3119 =head2 Localising Tied Arrays and Hashes Is Broken
3123 doesn't work as one would expect: the old value is restored
3124 incorrectly. This will be changed in a future release, but we don't
3125 know yet what the new semantics will exactly be. In any case, the
3126 change will break existing code that relies on the current
3127 (ill-defined) semantics, so just avoid doing this in general.
3129 =head2 Self-tying Problems
3131 Self-tying of arrays and hashes is broken in rather deep and
3132 hard-to-fix ways. As a stop-gap measure to avoid people from getting
3133 frustrated at the mysterious results (core dumps, most often), it is
3134 forbidden for now (you will get a fatal error even from an attempt).
3136 A change to self-tying of globs has caused them to be recursively
3137 referenced (see: L<perlobj/"Two-Phased Garbage Collection">). You
3138 will now need an explicit untie to destroy a self-tied glob. This
3139 behaviour may be fixed at a later date.
3141 Self-tying of scalars and IO thingies works.
3143 =head2 Building Extensions Can Fail Because Of Largefiles
3145 Some extensions like mod_perl are known to have issues with
3146 `largefiles', a change brought by Perl 5.6.0 in which file offsets
3147 default to 64 bits wide, where supported. Modules may fail to compile
3148 at all, or they may compile and work incorrectly. Currently, there
3149 is no good solution for the problem, but Configure now provides
3150 appropriate non-largefile ccflags, ldflags, libswanted, and libs
3151 in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the
3152 extensions that are having problems can try configuring themselves
3153 without the largefileness. This is admittedly not a clean solution,
3154 and the solution may not even work at all. One potential failure is
3155 whether one can (or, if one can, whether it's a good idea to) link
3156 together at all binaries with different ideas about file offsets;
3157 all this is platform-dependent.
3159 =head2 Unicode Support on EBCDIC Still Spotty
3161 Though mostly working, Unicode support still has problem spots on
3162 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
3163 regular expression constructs for code points less than 256: the
3164 C<pP> are testing for Unicode code points, not knowing about EBCDIC.
3166 =head2 The Compiler Suite Is Still Very Experimental
3168 The compiler suite is slowly getting better but it continues to be
3169 highly experimental. Use in production environments is discouraged.
3171 =head2 The Long Double Support Is Still Experimental
3173 The ability to configure Perl's numbers to use "long doubles",
3174 floating point numbers of hopefully better accuracy, is still
3175 experimental. The implementations of long doubles are not yet
3176 widespread and the existing implementations are not quite mature
3177 or standardised, therefore trying to support them is a rare
3178 and moving target. The gain of more precision may also be offset
3179 by slowdown in computations (more bits to move around, and the
3180 operations are more likely to be executed by less optimised
3183 =head2 Seen In Perl 5.7 But Gone Now
3185 C<Time::Piece> (previously known as C<Time::Object>) was removed
3186 because it was felt that it didn't have enough value in it to be a
3187 core module. It is still a useful module, though, and is available
3190 Perl 5.8 unfortunately does not build anymore on AmigaOS;
3191 this broke accidentally at some point. Since there are not that many
3192 Amiga developers available, we could not get this fixed and tested in
3195 =head1 Reporting Bugs
3197 If you find what you think is a bug, you might check the articles
3198 recently posted to the comp.lang.perl.misc newsgroup and the perl
3199 bug database at http://bugs.perl.org/ . There may also be
3200 information at http://www.perl.com/ , the Perl Home Page.
3202 If you believe you have an unreported bug, please run the B<perlbug>
3203 program included with your release. Be sure to trim your bug down
3204 to a tiny but sufficient test case. Your bug report, along with the
3205 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3206 analysed by the Perl porting team.
3210 The F<Changes> file for exhaustive details on what changed.
3212 The F<INSTALL> file for how to build Perl.
3214 The F<README> file for general stuff.
3216 The F<Artistic> and F<Copying> files for copyright information.
3220 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.