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. It now can deparse almost
1071 all of the standard test suite (so that the tests still succeed).
1072 There is a make target "test.deparse" for trying this out.
1076 Carp has now better interface documentation, and the @CARP_NOT
1077 interface has been added to get optional control over where errors
1078 are reported independently of @ISA.
1082 Class::Struct can now define the classes in compile time.
1086 Class::Struct now assigns the array/hash element if the accessor
1087 is called with an array/hash element as the B<sole> argument.
1091 The return value of Cwd::fastcwd() is now tainted.
1095 Data::Dumper now has an option to sort hashes.
1099 Data::Dumper now has an option to dump code references
1104 DB_File now supports newer Berkeley DB versions, among
1109 Devel::Peek now has an interface for the Perl memory statistics
1110 (this works only if you are using perl's malloc, and if you have
1111 compiled with debugging).
1115 The English module can now be used without the infamous performance
1118 use English '-no_match_vars';
1120 (Assuming, of course, that you don't need the troublesome variables
1121 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1122 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1126 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1127 leads to better portability.
1131 Fcntl, Socket, and Sys::Syslog have been rewritten to use the
1132 new-style constant dispatch section (see L<ExtUtils::Constant>).
1133 This means that they will be more robust and hopefully faster.
1137 File::Find now chdir()s correctly when chasing symbolic links.
1141 File::Find now has pre- and post-processing callbacks. It also
1142 correctly changes directories when chasing symbolic links. Callbacks
1143 (naughtily) exiting with "next;" instead of "return;" now work.
1147 File::Find is now (again) reentrant. It also has been made
1152 The warnings issued by File::Find now belong to their own category.
1153 You can enable/disable them with C<use/no warnings 'File::Find';>.
1157 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1158 prototype mismatch with CORE::glob().
1162 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1163 the returned list of filenames.
1167 IPC::Open3 now allows the use of numeric file descriptors.
1171 IO::Socket now has an atmark() method, which returns true if the socket
1172 is positioned at the out-of-band mark. The method is also exportable
1173 as a sockatmark() function.
1177 IO::Socket::INET has support for the ReusePort option (if your
1178 platform supports it). The Reuse option now has an alias, ReuseAddr.
1179 For clarity, you may want to prefer ReuseAddr.
1183 IO::Socket::INET now supports a value of zero for C<LocalPort>
1184 (usually meaning that the operating system will make one up.)
1188 'use lib' now works identically to @INC. Removing directories
1189 with 'no lib' now works.
1193 Math::BigFloat and Math::BigInt have undergone a full rewrite.
1194 They are now magnitudes faster, and they support various
1195 bignum libraries such as GMP and PARI as their backends.
1199 Math::Complex handles inf, NaN etc., better.
1203 Net::Ping has been considerably enhanced: multihoming is now supported,
1204 Win32 functionality is better, there is now time measuring
1205 functionality (optionally high-resolution using Time::HiRes),
1206 and there is now "external" protocol which uses Net::Ping::External
1207 module which runs your external ping utility and parses the output.
1208 A version of Net::Ping::External is available in CPAN.
1210 Note that some of the Net::Ping tests are disabled when running
1211 under the Perl distribution since one cannot assume one or more
1212 of the following: enabled echo port at localhost, full Internet
1213 connectivity, or sympathetic firewalls. You can set the environment
1214 variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test
1215 suite to enable all the Net::Ping tests.
1219 POSIX::sigaction() is now much more flexible and robust.
1220 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1221 handlers, installing new handlers was not atomic.
1225 In Safe, C<%INC> is now localised in a Safe compartment so that
1230 In SDBM_File on dosish platforms, some keys went missing because of
1231 lack of support for files with "holes". A workaround for the problem
1236 In Search::Dict one can now have a pre-processing hook for the
1237 lines being searched.
1241 The Shell module now has an OO interface.
1245 In Sys::Syslog there is now a failover mechanism that will go
1246 through alternative connection mechanisms until the message
1247 is successfully logged.
1251 The Test module has been significantly enhanced.
1255 Time::Local::timelocal() does not handle fractional seconds anymore.
1256 The rationale is that neither does localtime(), and timelocal() and
1257 localtime() are supposed to be inverses of each other.
1261 The vars pragma now supports declaring fully qualified variables.
1262 (Something that C<our()> does not and will not support.)
1266 The C<utf8::> name space (as in the pragma) provides various
1267 Perl-callable functions to provide low level access to Perl's
1268 internal Unicode representation. At the moment only length()
1269 has been implemented.
1273 =head1 Utility Changes
1279 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1284 F<emacs/e2ctags.pl> is now much faster.
1288 C<enc2xs> is a tool for people adding their own encodings to the
1293 C<h2ph> now supports C trigraphs.
1297 C<h2xs> now produces a template README.
1301 C<h2xs> now uses C<Devel::PPPort> for better portability between
1302 different versions of Perl.
1306 C<h2xs> uses the new L<ExtUtils::Constant|ExtUtils::Constant> module
1307 which will affect newly created extensions that define constants.
1308 Since the new code is more correct (if you have two constants where the
1309 first one is a prefix of the second one, the first constant B<never>
1310 got defined), less lossy (it uses integers for integer constant,
1311 as opposed to the old code that used floating point numbers even for
1312 integer constants), and slightly faster, you might want to consider
1313 regenerating your extension code (the new scheme makes regenerating
1314 easy). L<h2xs> now also supports C trigraphs.
1318 C<libnetcfg> has been added to configure libnet.
1322 C<perlbug> is now much more robust. It also sends the bug report to
1323 perl.org, not perl.com.
1327 C<perlcc> has been rewritten and its user interface (that is,
1328 command line) is much more like that of the UNIX C compiler, cc.
1329 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1330 B<Note that perlcc is still considered very experimental and
1335 C<perlivp> is a new Installation Verification Procedure utility
1336 for running any time after installing Perl.
1340 C<piconv> is an implementation of the character conversion utility
1341 C<iconv>, demonstrating the new Encode module.
1345 C<pod2html> now allows specifying a cache directory.
1349 C<pod2html> now produces XHTML 1.0.
1353 C<pod2html> now understands POD written using different line endings
1354 (PC-like CRLF versus UNIX-like LF versus MacClassic-like CR).
1358 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1359 implementation of sed in Perl: you can use the sed functionality by
1360 using the C<psed> utility.)
1364 C<xsubpp> now understands POD documentation embedded in the *.xs files.
1368 C<xsubpp> now supports the OUT keyword.
1372 =head1 New Documentation
1378 perl56delta details the changes between the 5.005 release and the
1383 perlclib documents the internal replacements for standard C library
1384 functions. (Interesting only for extension writers and Perl core
1389 perldebtut is a Perl debugging tutorial.
1393 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1397 perlintro is a gentle introduction to Perl.
1401 perliol documents the internals of PerlIO with layers.
1405 perlmodstyle is a style guide for writing modules.
1409 perlnewmod tells about writing and submitting a new module.
1413 perlpacktut is a pack() tutorial.
1417 perlpod has been rewritten to be clearer and to record the best
1418 practices gathered over the years.
1422 perlpodspec is a more formal specification of the pod format,
1423 mainly of interest for writers of pod applications, not to
1424 people writing in pod.
1428 perlretut is a regular expression tutorial.
1432 perlrequick is a regular expressions quick-start guide.
1433 Yes, much quicker than perlretut.
1437 perltodo has been updated.
1441 perltootc has been renamed as perltooc (to not to conflict
1442 with perltoot in filesystems restricted to "8.3" names).
1446 perluniintro is an introduction to using Unicode in Perl.
1447 (perlunicode is more of a detailed reference and background
1452 perlutil explains the command line utilities packaged with the Perl
1457 The following platform-specific documents are available before
1458 the installation as README.I<platform>, and after the installation
1461 perlaix perlamiga perlapollo perlbeos perlbs2000
1462 perlce perlcygwin perldgux perldos perlepoc perlhpux
1463 perlhurd perlmachten perlmacos perlmint perlmpeix
1464 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1465 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1467 Eastern Asian Perl users are now welcomed in their own languages:
1468 README.jp (Japanese), README.ko (Korean), README.cn (simplified
1469 Chinese) and README.tw (traditional Chinese), which are written in
1470 normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These
1471 will get installed as
1473 perljp perlko perlcn perltw
1479 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1480 confusion with the Perl POSIX module.
1484 The documentation for the WinCE platform is called perlce (README.ce
1485 in the source code kit), to avoid confusion with the perlwin32
1486 documentation on 8.3-restricted filesystems.
1490 =head1 Performance Enhancements
1496 map() could get pathologically slow when the result list it generates
1497 is larger than the source list. The performance has been improved for
1502 sort() has been changed to use primarily mergesort internally as
1503 opposed to the earlier quicksort. For very small lists this may
1504 result in slightly slower sorting times, but in general the speedup
1505 should be at least 20%. Additional bonuses are that the worst case
1506 behaviour of sort() is now better (in computer science terms it now
1507 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1508 worst-case run time behaviour), and that sort() is now stable
1509 (meaning that elements with identical keys will stay ordered as they
1510 were before the sort). See the C<sort> pragma for information.
1512 The story in more detail: suppose you want to serve yourself a little
1515 @digits = ( 3,1,4,1,5,9 );
1517 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1518 Which C<1> comes first is hard to know, since one C<1> looks pretty
1519 much like any other. You can regard this as totally trivial,
1520 or somewhat profound. However, if you just want to sort the even
1521 digits ahead of the odd ones, then what will
1523 sort { ($a % 2) <=> ($b % 2) } @digits;
1525 yield? The only even digit, C<4>, will come first. But how about
1526 the odd numbers, which all compare equal? With the quicksort algorithm
1527 used to implement Perl 5.6 and earlier, the order of ties is left up
1528 to the sort. So, as you add more and more digits of Pi, the order
1529 in which the sorted even and odd digits appear will change.
1530 and, for sufficiently large slices of Pi, the quicksort algorithm
1531 in Perl 5.8 won't return the same results even if reinvoked with the
1532 same input. The justification for this rests with quicksort's
1533 worst case behavior. If you run
1535 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1537 (something you might approximate if you wanted to merge two sorted
1538 arrays using sort), doubling $N doesn't just double the quicksort time,
1539 it I<quadruples> it. Quicksort has a worst case run time that can
1540 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1541 on patterns that may well arise in normal use. You won't notice this
1542 for small arrays, but you I<will> notice it with larger arrays,
1543 and you may not live long enough for the sort to complete on arrays
1544 of a million elements. So the 5.8 quicksort scrambles large arrays
1545 before sorting them, as a statistical defence against quadratic behaviour.
1546 But that means if you sort the same large array twice, ties may be
1547 broken in different ways.
1549 Because of the unpredictability of tie-breaking order, and the quadratic
1550 worst-case behaviour, quicksort was I<almost> replaced completely with
1551 a stable mergesort. I<Stable> means that ties are broken to preserve
1552 the original order of appearance in the input array. So
1554 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1556 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1557 appear in the output in the same order they appeared in the input.
1558 Mergesort has worst case O(N log N) behaviour, the best value
1559 attainable. And, ironically, this mergesort does particularly
1560 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1561 in O(N) time. But quicksort was rescued at the last moment because
1562 it is faster than mergesort on certain inputs and platforms.
1563 For example, if you really I<don't> care about the order of even
1564 and odd digits, quicksort will run in O(N) time; it's very good
1565 at sorting many repetitions of a small number of distinct elements.
1566 The quicksort divide and conquer strategy works well on platforms
1567 with relatively small, very fast, caches. Eventually, the problem gets
1568 whittled down to one that fits in the cache, from which point it
1569 benefits from the increased memory speed.
1571 Quicksort was rescued by implementing a sort pragma to control aspects
1572 of the sort. The B<stable> subpragma forces stable behaviour,
1573 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1574 subpragmas are heavy-handed ways to select the underlying implementation.
1575 The leading C<_> is a reminder that these subpragmas may not survive
1576 beyond 5.8. More appropriate mechanisms for selecting the implementation
1577 exist, but they wouldn't have arrived in time to save quicksort.
1581 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1582 ( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is
1583 reasonably fast while producing a much better spread of values than
1584 the old hashing algorithm (originally by Chris Torek, later tweaked by
1585 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1586 all 3-char printable ASCII keys comes much closer to passing the
1587 DIEHARD random number generation tests. According to perlbench, this
1588 change has not affected the overall speed of Perl.
1592 unshift() should now be noticeably faster.
1596 =head1 Installation and Configuration Improvements
1598 =head2 Generic Improvements
1604 INSTALL now explains how you can configure Perl to use 64-bit
1605 integers even on non-64-bit platforms.
1609 Policy.sh policy change: if you are reusing a Policy.sh file
1610 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1611 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1612 them will now be changed to the new prefix, /foo/bar. (Previously
1613 only $prefix changed.) If you do not like this new behaviour,
1614 specify prefix, siteprefix, and vendorprefix explicitly.
1618 A new optional location for Perl libraries, otherlibdirs, is available.
1619 It can be used for example for vendor add-ons without disturbing Perl's
1620 own library directories.
1624 In many platforms, the vendor-supplied 'cc' is too stripped-down to
1625 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1626 to be the case and 'cc' does not seem to be the GNU C compiler
1627 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1631 gcc needs to closely track the operating system release to avoid
1632 build problems. If Configure finds that gcc was built for a different
1633 operating system release than is running, it now gives a clearly visible
1634 warning that there may be trouble ahead.
1638 Since Perl 5.8 is not binary-compatible with previous releases
1639 of Perl, Configure no longer suggests including the 5.005
1644 Configure C<-S> can now run non-interactively.
1648 Configure support for pdp11-style memory models has been removed due
1653 configure.gnu now works with options with whitespace in them.
1657 installperl now outputs everything to STDERR.
1661 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1662 get appended to the $Config{archname} (also known as $^O) anymore.
1663 Instead, if you explicitly choose not to use perlio (Configure command
1664 line option -Uuseperlio), you will get "-stdio" appended.
1668 Another change related to the architecture name is that "-64all"
1669 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1670 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1674 In AFS installations, one can configure the root of the AFS to be
1675 somewhere else than the default F</afs> by using the Configure
1676 parameter C<-Dafsroot=/some/where/else>.
1680 APPLLIB_EXP, a lesser-known configuration-time definition, has been
1681 documented. It can be used to prepend site-specific directories
1682 to Perl's default search path (@INC); see INSTALL for information.
1686 The version of Berkeley DB used when the Perl (and, presumably, the
1687 DB_File extension) was built is now available as
1688 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1689 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1690 DB_VERSION_PATCH_CFG> from C.
1694 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1695 has been documented in INSTALL.
1699 If you have CPAN access (either network or a local copy such as a
1700 CD-ROM) you can during specify extra modules to Configure to build and
1701 install with Perl using the -Dextras=... option. See INSTALL for
1706 In addition to config.over, a new override file, config.arch, is
1707 available. This file is supposed to be used by hints file writers
1708 for architecture-wide changes (as opposed to config.over which is
1709 for site-wide changes).
1713 If your file system supports symbolic links, you can build Perl outside
1714 of the source directory by
1716 mkdir /tmp/perl/build/directory
1717 cd /tmp/perl/build/directory
1718 sh /path/to/perl/source/Configure -Dmksymlinks ...
1720 This will create in /tmp/perl/build/directory a tree of symbolic links
1721 pointing to files in /path/to/perl/source. The original files are left
1722 unaffected. After Configure has finished, you can just say
1726 and Perl will be built and tested, all in /tmp/perl/build/directory.
1730 For Perl developers, several new make targets for profiling
1731 and debugging have been added; see L<perlhack>.
1737 Use of the F<gprof> tool to profile Perl has been documented in
1738 L<perlhack>. There is a make target called "perl.gprof" for
1739 generating a gprofiled Perl executable.
1743 If you have GCC 3, there is a make target called "perl.gcov" for
1744 creating a gcoved Perl executable for coverage analysis. See
1749 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1750 have been added; see L<perlhack> for more information about pixie and
1757 Guidelines of how to construct minimal Perl installations have
1758 been added to INSTALL.
1762 The Thread extension is now not built at all under ithreads
1763 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1764 Thread extension requires being Configured with C<-Duse5005threads>).
1766 But note that the Thread.pm interface is now shared by both
1771 The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
1772 floating-point numbers is now more picky about using sprintf %.*g
1773 rules for the conversion. Some platforms that used to use gcvt may
1774 now resort to the slower sprintf.
1778 The obsolete method of making a special (e.g., debugging) flavor
1781 make LIBPERL=libperld.a
1783 has been removed. Use -DDEBUGGING instead.
1787 =head2 New Or Improved Platforms
1789 For the list of platforms known to support Perl,
1790 see L<perlport/"Supported Platforms">.
1796 AIX dynamic loading should be now better supported.
1800 AIX should now work better with gcc, threads, and 64-bitness. Also the
1801 long doubles support in AIX should be better now. See L<perlaix>.
1805 AtheOS ( http://www.atheos.cx/ ) is a new platform.
1809 BeOS has been reclaimed.
1813 The DG/UX platform now supports 5.005-style threads.
1818 The DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near
1823 EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA)
1824 have been regained. Many test suite tests still fail and the
1825 co-existence of Unicode and EBCDIC isn't quite settled, but the
1826 situation is much better than with Perl 5.6. See L<perlos390>,
1827 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1831 Building perl with -Duseithreads or -Duse5005threads now works under
1832 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1833 need a thread library package installed. See README.hpux.
1837 MacOS Classic (MacPerl has of course been available since
1838 perl 5.004 but now the source code bases of standard Perl
1839 and MacPerl have been synchronised)
1843 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1844 filesystems. (The case-insensitivity used to confuse the Perl build
1849 NCR MP-RAS is now supported.
1853 All the NetBSD specific patches (except for the installation
1854 specific ones) have been merged back to the main distribution.
1858 NetWare from Novell is now supported. See L<perlnetware>.
1862 NonStop-UX is now supported.
1866 NEC SUPER-UX is now supported.
1870 All the OpenBSD specific patches (except for the installation
1871 specific ones) have been merged back to the main distribution.
1875 Perl has been tested with the GNU pth userlevel thread package
1876 ( http://www.gnu.org/software/pth/pth.html ) . All but one thread
1877 test worked, and that one failure was because of test results arriving
1878 in unexpected order.
1882 Stratus VOS is now supported using Perl's native build method
1883 (Configure). This is the recommended method to build Perl on
1884 VOS. The older methods, which build miniperl, are still
1885 available. See L<perlvos>.
1889 The Amdahl UTS UNIX mainframe platform is now supported.
1893 WinCE is now supported. See L<perlce>.
1897 z/OS (formerly known as OS/390, formerly known as MVS OE) now has
1898 support for dynamic loading. This is not selected by default,
1899 however, you must specify -Dusedl in the arguments of Configure.
1903 =head1 Selected Bug Fixes
1905 Numerous memory leaks and uninitialized memory accesses have been
1906 hunted down. Most importantly, anonymous subs used to leak quite
1913 The autouse pragma didn't work for Multi::Part::Function::Names.
1917 caller() could cause core dumps in certain situations. Carp was sometimes
1918 affected by this problem. In particular, caller() now returns a
1919 subroutine name of C<(unknown)> for subroutines that have been removed
1920 from the symbol table.
1924 chop(@list) in list context returned the characters chopped in
1925 reverse order. This has been reversed to be in the right order.
1929 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1930 when building the Perl binary. The only exception to this is SunOS 4.x,
1935 The behaviour of non-decimal but numeric string constants such as
1936 "0x23" was platform-dependent: in some platforms that was seen as 35,
1937 in some as 0, in some as a floating point number (don't ask). This
1938 was caused by Perl's using the operating system libraries in a situation
1939 where the result of the string to number conversion is undefined: now
1940 Perl consistently handles such strings as zero in numeric contexts.
1944 The order of DESTROYs has been made more predictable.
1948 Several debugger fixes: exit code now reflects the script exit code,
1949 condition C<"0"> now treated correctly, the C<d> command now checks
1950 line number, C<$.> no longer gets corrupted, and all debugger output
1951 now goes correctly to the socket if RemotePort is set.
1955 Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1956 when statically building extensions into perl. This has been corrected.
1960 L<dprofpp> -R didn't work.
1964 C<*foo{FORMAT}> now works.
1968 Infinity is now recognized as a number.
1972 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1973 the Tk extension with 5.6.0.)
1977 Lexicals I: lexicals outside an eval "" weren't resolved
1978 correctly inside a subroutine definition inside the eval "" if they
1979 were not already referenced in the top level of the eval""ed code.
1983 Lexicals II: lexicals leaked at file scope into subroutines that
1984 were declared before the lexicals.
1988 Lexical warnings now propagating correctly between scopes
1989 and into C<eval "...">.
1993 C<use warnings qw(FATAL all)> did not work as intended. This has been
1998 warnings::enabled() now reports the state of $^W correctly if the caller
1999 isn't using lexical warnings.
2003 Line renumbering with eval and C<#line> now works.
2007 Fixed numerous memory leaks, especially in eval "".
2011 Localised tied variables no longer leak memory
2014 tie my %tied_hash => 'Tie::StdHash';
2018 # Used to leak memory every time local() was called;
2019 # in a loop, this added up.
2020 local($tied_hash{Foo}) = 1;
2024 Localised hash elements (and %ENV) are correctly unlocalised to not
2025 exist, if they didn't before they were localised.
2029 tie my %tied_hash => 'Tie::StdHash';
2033 # Nothing has set the FOO element so far
2035 { local $tied_hash{FOO} = 'Bar' }
2037 # This used to print, but not now.
2038 print "exists!\n" if exists $tied_hash{FOO};
2040 As a side effect of this fix, tied hash interfaces B<must> define
2041 the EXISTS and DELETE methods.
2045 mkdir() now ignores trailing slashes in the directory name,
2046 as mandated by POSIX.
2050 Some versions of glibc have a broken modfl(). This affects builds
2051 with C<-Duselongdouble>. This version of Perl detects this brokenness
2052 and has a workaround for it. The glibc release 2.2.2 is known to have
2053 fixed the modfl() bug.
2057 Modulus of unsigned numbers now works (4063328477 % 65535 used to
2058 return 27406, instead of 27047).
2062 Some "not a number" warnings introduced in 5.6.0 eliminated to be
2063 more compatible with 5.005. Infinity is now recognised as a number.
2067 Numeric conversions did not recognize changes in the string value
2068 properly in certain circumstances.
2072 Attributes (such as :shared) didn't work with our().
2076 our() variables will not cause "will not stay shared" warnings.
2080 "our" variables of the same name declared in two sibling blocks
2081 resulted in bogus warnings about "redeclaration" of the variables.
2082 The problem has been corrected.
2086 pack "Z" now correctly terminates the string with "\0".
2090 Fix password routines which in some shadow password platforms
2091 (e.g. HP-UX) caused getpwent() to return every other entry.
2095 The PERL5OPT environment variable (for passing command line arguments
2096 to Perl) didn't work for more than a single group of options.
2100 PERL5OPT with embedded spaces didn't work.
2104 printf() no longer resets the numeric locale to "C".
2108 C<qw(a\\b)> now parses correctly as C<'a\\b'>: that is, as three
2109 characters, not four.
2113 pos() did not return the correct value within s///ge in earlier
2114 versions. This is now handled correctly.
2118 Printing quads (64-bit integers) with printf/sprintf now works
2119 without the q L ll prefixes (assuming you are on a quad-capable platform).
2123 Regular expressions on references and overloaded scalars now work.
2127 Right-hand side magic (GMAGIC) could in many cases such as string
2128 concatenation be invoked too many times.
2132 scalar() now forces scalar context even when used in void context.
2136 SOCKS support is now much more robust.
2140 sort() arguments are now compiled in the right wantarray context
2141 (they were accidentally using the context of the sort() itself).
2142 The comparison block is now run in scalar context, and the arguments
2143 to be sorted are always provided list context.
2147 Changed the POSIX character class C<[[:space:]]> to include the (very
2148 rarely used) vertical tab character. Added a new POSIX-ish character
2149 class C<[[:blank:]]> which stands for horizontal whitespace
2150 (currently, the space and the tab).
2154 The tainting behaviour of sprintf() has been rationalized. It does
2155 not taint the result of floating point formats anymore, making the
2156 behaviour consistent with that of string interpolation.
2160 Some cases of inconsistent taint propagation (such as within hash
2161 values) have been fixed.
2165 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
2166 of simple pattern matches. These are now handled better.
2170 Regular expression debug output (whether through C<use re 'debug'>
2171 or via C<-Dr>) now looks better.
2175 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
2180 Use of $& could trigger a core dump under some situations. This
2185 The regular expression captured submatches ($1, $2, ...) are now
2186 more consistently unset if the match fails, instead of leaving false
2187 data lying around in them.
2191 readline() on files opened in "slurp" mode could return an extra
2192 "" (blank line) at the end in certain situations. This has been
2197 Autovivification of symbolic references of special variables described
2198 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
2203 Sys::Syslog ignored the C<LOG_AUTH> constant.
2207 All but the first argument of the IO syswrite() method are now optional.
2211 $AUTOLOAD, sort(), lock(), and spawning subprocesses
2212 in multiple threads simultaneously are now thread-safe.
2216 Tie::Array's SPLICE method was broken.
2220 Allow a read-only string on the left-hand side of a non-modifying tr///.
2224 If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
2225 correctly pass to it.
2229 Several Unicode fixes.
2235 BOMs (byte order marks) at the beginning of Perl files
2236 (scripts, modules) should now be transparently skipped.
2237 UTF-16 and UCS-2 encoded Perl files should now be read correctly.
2241 The character tables have been updated to Unicode 3.2.0.
2245 Comparing with utf8 data does not magically upgrade non-utf8 data
2246 into utf8. (This was a problem for example if you were mixing data
2247 from I/O and Unicode data: your output might have got magically encoded
2252 Generating illegal Unicode code points such as U+FFFE, or the UTF-16
2253 surrogates, now also generates an optional warning.
2257 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2261 Concatenation with the C<.> operator or via variable interpolation,
2262 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2263 substitution with C<s///>, single-quoted UTF8, should now work.
2267 The C<tr///> operator now works. Note that the C<tr///CU>
2268 functionality has been removed (but see pack('U0', ...)).
2272 C<eval "v200"> now works.
2276 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2277 This has been corrected.
2281 Zero entries were missing from the Unicode classes such as C<IsDigit>.
2287 Large unsigned numbers (those above 2**31) could sometimes lose their
2288 unsignedness, causing bogus results in arithmetic operations.
2292 The Perl parser has been stress tested using both random input and
2293 Markov chain input and the few found crashes and lockups have been
2298 =head2 Platform Specific Changes and Fixes
2306 Perl now works on post-4.0 BSD/OSes.
2312 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2318 Numerous updates; currently synchronised with Cygwin 1.3.10.
2322 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2328 EPOC update after Perl 5.6.0. See README.epoc.
2334 Perl now works on post-3.0 FreeBSDs.
2340 README.hpux updated; C<Configure -Duse64bitall> now works;
2341 now uses HP-UX malloc instead of Perl malloc.
2347 Numerous compilation flag and hint enhancements; accidental mixing
2348 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2358 Long doubles should now work (see INSTALL).
2362 Linux previously had problems related to sockaddrlen when using
2363 accept(), recvfrom() (in Perl: recv()), getpeername(), and
2372 Compilation of the standard Perl distribution in MacOS Classic should
2373 now work if you have the Metrowerks development environment and
2374 the missing Mac-specific toolkit bits. Contact the macperl mailing
2381 MPE/iX update after Perl 5.6.0. See README.mpeix.
2385 NetBSD/threads: try installing the GNU pth (should be in the
2386 packages collection, or http://www.gnu.org/software/pth/),
2387 and Configure with -Duseithreads.
2393 Perl now works on NetBSD/sparc.
2399 Now works with usethreads (see INSTALL).
2405 64-bitness using the Sun Workshop compiler now works.
2411 The native build method requires at least VOS Release 14.5.0
2412 and GNU C++/GNU Tools 2.0.1 or later. The Perl pack function
2413 now maps overflowed values to +infinity and underflowed values
2418 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2420 The operating system version letter now recorded in $Config{osvers}.
2421 Allow compiling with gcc (previously explicitly forbidden). Compiling
2422 with gcc still not recommended because buggy code results, even with
2429 Fixed various alignment problems that lead into core dumps either
2430 during build or later; no longer dies on math errors at runtime;
2431 now using full quad integers (64 bits), previously was using
2432 only 46 bit integers for speed.
2438 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2439 (see INSTALL); now works with Perl's malloc.
2441 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2442 unimplemented. It now works as documented.
2444 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2445 was that a pid of -1 would cause a wildcard search of all processes on
2448 POSIX-style signals are now emulated much better on VMS versions prior
2451 The C<system> function and backticks operator have improved
2452 functionality and better error handling.
2454 File access tests now use current process privileges rather than the
2455 user's default privileges, which could sometimes result in a mismatch
2456 between reported access and actual access.
2458 There is a new C<kill> implementation based on C<sys$sigprc> that allows
2459 older VMS systems (pre-7.0) to use C<kill> to send signals rather than
2460 simply force exit. This implementation also allows later systems to
2461 call C<kill> from within a signal handler.
2463 Iterative logical name translations are now limited to 10 iterations in
2464 imitation of SHOW LOGICAL and other OpenVMS facilities.
2474 accept() no longer leaks memory.
2478 Borland C++ v5.5 is now a supported compiler that can build Perl.
2479 However, the generated binaries continue to be incompatible with those
2480 generated by the other supported compilers (GCC and Visual C++).
2484 Better chdir() return value for a non-existent directory.
2488 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2492 New %ENV entries now propagate to subprocesses.
2496 Current directory entries in %ENV are now correctly propagated to child
2501 $ENV{LIB} now used to search for libs under Visual C.
2505 fork() emulation has been improved in various ways, but still continues
2506 to be experimental. See L<perlfork> for known bugs and caveats.
2510 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2514 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2515 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2519 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2523 The makefiles now provide a single switch to bulk-enable all the features
2524 enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2528 Allow REG_EXPAND_SZ keys in the registry.
2532 Can now send() from all threads, not just the first one.
2536 Fake signal handling reenabled, bugs and all.
2540 %SIG has been enabled under USE_ITHREADS, but its use is completely
2541 unsupported under all configurations.
2545 Less stack reserved per thread so that more threads can run
2546 concurrently. (Still 16M per thread.)
2550 C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
2551 (works better when perl is running as service).
2555 Better UNC path handling under ithreads.
2559 wait(), waitpid(), and backticks now return the correct exit status
2564 Win64 compilation is now supported.
2568 winsock handle leak fixed.
2574 =head1 New or Changed Diagnostics
2580 The lexical warnings category "deprecated" is no longer a sub-category
2581 of the "syntax" category. It is now a top-level category in its own
2586 All regular expression compilation error messages are now hopefully
2587 easier to understand both because the error message now comes before
2588 the failed regex and because the point of failure is now clearly
2589 marked by a C<E<lt>-- HERE> marker.
2593 The various "opened only for", "on closed", "never opened" warnings
2594 drop the C<main::> prefix for filehandles in the C<main> package,
2595 for example C<STDIN> instead of C<main::STDIN>.
2599 The "Unrecognized escape" warning has been extended to include C<\8>,
2600 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2604 Two new debugging options have been added: if you have compiled your
2605 Perl with debugging, you can use the -DT and -DR options to trace
2606 tokenising and to add reference counts to displaying variables,
2611 The debugger (perl5db.pl) has been modified to present a more
2612 consistent commands interface, via (CommandSet=580). perl5db.t was
2613 also added to test the changes, and as a placeholder for further tests.
2619 The debugger has a new C<dumpDepth> option to control the maximum
2620 depth to which nested structures are dumped. The C<x> command has
2621 been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a
2622 depth of at most I<N> levels.
2626 The debugger can now show lexical variables if you have the CPAN
2627 module PadWalker installed.
2631 If an attempt to use a (non-blessed) reference as an array index
2632 is made, a warning is given.
2636 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2637 now give a warning. This may be a problem for generated and evaled
2642 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2643 using the C<"C"> format you will get an optional warning. Similarly
2644 for the C<"c"> format and a number less than -128 or more than 127.
2648 Certain regex modifiers such as C<(?o)> make sense only if applied to
2649 the entire regex. You will get an optional warning if you try to do
2654 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2655 has been deprecated for a while. Now you will get an optional warning.
2659 Using C<sort> in scalar context now issues an optional warning.
2660 This didn't do anything useful, as the sort was not performed.
2664 =head1 Changed Internals
2670 perlapi.pod (a companion to perlguts) now attempts to document the
2675 You can now build a really minimal perl called microperl.
2676 Building microperl does not require even running Configure;
2677 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2678 many assumptions, some of which may be too bold; the resulting
2679 executable may crash or otherwise misbehave in wondrous ways.
2680 For careful hackers only.
2684 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2685 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2686 interfaces to the publicised API. For the full list of the available
2687 APIs see L<perlapi>.
2691 Made possible to propagate customised exceptions via croak()ing.
2695 Now xsubs can have attributes just like subs. (Well, at least the
2696 built-in attributes.)
2700 dTHR and djSP have been obsoleted; the former removed (because it's
2701 a no-op) and the latter replaced with dSP.
2705 PERL_OBJECT has been completely removed.
2709 The MAGIC constants (e.g. C<'P'>) have been macrofied
2710 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2711 and maintainability.
2715 The regex compiler now maintains a structure that identifies nodes in
2716 the compiled bytecode with the corresponding syntactic features of the
2717 original regex expression. The information is attached to the new
2718 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2719 complete information.
2723 The C code has been made much more C<gcc -Wall> clean. Some warning
2724 messages still remain in some platforms, so if you are compiling with
2725 gcc you may see some warnings about dubious practices. The warnings
2726 are being worked on.
2730 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2734 Documentation on how to use the Perl source repository has been added
2735 to F<Porting/repository.pod>.
2739 There are now several profiling make targets.
2743 =head1 Security Vulnerability Closed
2745 (This change was already made in 5.7.0 but bears repeating here.)
2747 A potential security vulnerability in the optional suidperl component
2748 of Perl was identified in August 2000. suidperl is neither built nor
2749 installed by default. As of November 2001 the only known vulnerable
2750 platform is Linux, most likely all Linux distributions. CERT and
2751 various vendors and distributors have been alerted about the vulnerability.
2752 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2753 for more information.
2755 The problem was caused by Perl trying to report a suspected security
2756 exploit attempt using an external program, /bin/mail. On Linux
2757 platforms the /bin/mail program had an undocumented feature which
2758 when combined with suidperl gave access to a root shell, resulting in
2759 a serious compromise instead of reporting the exploit attempt. If you
2760 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2761 suidperl is not installed, you are safe.
2763 The exploit attempt reporting feature has been completely removed from
2764 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2765 from all the Perl 5.7 releases), so that particular vulnerability
2766 isn't there anymore. However, further security vulnerabilities are,
2767 unfortunately, always possible. The suidperl functionality is most
2768 probably going to be removed in Perl 5.10. In any case, suidperl
2769 should only be used by security experts who know exactly what they are
2770 doing and why they are using suidperl instead of some other solution
2771 such as sudo ( see http://www.courtesan.com/sudo/ ).
2775 Several new tests have been added, especially for the F<lib> and F<ext>
2776 subsections. There are now about 65 000 individual tests (spread over
2777 about 700 test scripts), in the regression suite (5.6.1 has about
2778 11700 tests, in 258 test scripts) Many of the new tests are of course
2779 introduced by the new modules, but still in general Perl is now more
2782 Because of the large number of tests, running the regression suite
2783 will take considerably longer time than it used to: expect the suite
2784 to take up to 4-5 times longer to run than in perl 5.6. On a really
2785 fast machine you can hope to finish the suite in about 6-8 minutes
2788 The tests are now reported in a different order than in earlier Perls.
2789 (This happens because the test scripts from under t/lib have been moved
2790 to be closer to the library/extension they are testing.)
2792 =head1 Known Problems
2800 If using the AIX native make command, instead of just "make" issue
2801 "make all". In some setups the former has been known to spuriously
2802 also try to run "make install". Alternatively, you may want to use
2807 In AIX 4.2, Perl extensions that use C++ functions that use statics
2808 may have problems in that the statics are not getting initialized.
2809 In newer AIX releases, this has been solved by linking Perl with
2810 the libC_r library, but unfortunately in AIX 4.2 the said library
2811 has an obscure bug where the various functions related to time
2812 (such as time() and gettimeofday()) return broken values, and
2813 therefore in AIX 4.2 Perl is not linked against libC_r.
2817 vac 5.0.0.0 May Produce Buggy Code For Perl
2819 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2820 resulting in a few random tests failing when run as part of "make
2821 test", but when the failing tests are run by hand, they succeed.
2822 We suggest upgrading to at least vac version 5.0.1.0, that has been
2823 known to compile Perl correctly. "lslpp -L|grep vac.C" will tell
2824 you the vac version. See README.aix.
2828 If building threaded Perl, you may get compilation warning from pp_sys.c:
2830 "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
2832 This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()
2833 having slightly different types for their first argument.
2837 =head2 Alpha systems with old gccs fail several tests
2839 If you see op/pack, op/pat, op/regexp, or ext/Storable tests failing
2840 in a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc.
2841 gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 may
2842 be even better. (RedHat Linux/alpha with gcc 3.1 reported no problems,
2843 as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable to
2844 use the bundled C compiler.)
2848 Perl 5.8.0 doesn't build in AmigaOS. It broke at some point
2849 during the ithreads work and we could not find Amiga experts
2850 to unbreak the problems.
2854 The following tests fail on 5.8.0 Perl in BeOS Personal 5.03:
2856 t/op/lfs............................FAILED at test 17
2857 t/op/magic..........................FAILED at test 24
2858 ext/POSIX/t/sigaction...............FAILED at test 13
2859 ext/POSIX/t/waitpid.................FAILED at test 1
2861 See L<perlbeos> (README.beos) for more details.
2863 =head2 Cygwin "unable to remap"
2865 For example when building the Tk extension for Cygwin,
2866 you may get an error message saying "unable to remap".
2867 This is known problem with Cygwin, and a workaround is
2868 detailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html
2870 =head2 ext/threads/t/libc
2872 If this test fails, it indicates that your libc (C library) is not
2873 threadsafe. This particular test stress tests the localtime() call to
2874 find out whether it is threadsafe. See L<perlthrtut> for more information.
2876 =head2 FreeBSD Failing locale Test 117 For ISO8859-15 Locales
2878 The ISO8859-15 locales may fail the locale test 117 in FreeBSD.
2879 This is caused by the characters \xFF (y with diaeresis) and \xBE
2880 (Y with diaeresis) not behaving correctly when being matched
2883 =head2 IRIX fails ext/List/Util/t/shuffle.t
2885 IRIX with MIPSpro 7.3.1.3m compiler may fail the said List::Util test
2886 by dumping core. This seems to be a compiler error since if compiled
2887 with gcc no core dump ensues, and no failures on the said test on any
2890 =head2 Modifying $_ Inside for(..)
2894 works without complaint. It shouldn't. (You should be able to
2895 modify only lvalue elements inside the loops.) You can see the
2896 correct behaviour by replacing the 1..5 with 1, 2, 3, 4, 5.
2898 =head2 mod_perl 1.26 Doesn't Build With Threaded Perl
2900 Use mod_perl 1.27 or higher.
2902 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2904 Don't panic. Read the 'make test' section of INSTALL instead.
2906 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2908 If perl is configured with -Duse64bitall, the successful result of the
2909 subtest 10 of lib/posix may arrive before the successful result of the
2910 subtest 9, which confuses the test harness so much that it thinks the
2913 =head2 Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint
2915 This is a known bug in the glibc 2.2.5 with long long integers.
2916 ( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )
2918 =head2 Linux With Sfio Fails op/misc Test 48
2922 =head2 libwww-perl (LWP) fails base/date #51
2924 Use libwww-perl 5.65 or later.
2928 Please remember to set your environment variable LC_ALL to "C"
2929 (setenv LC_ALL C) before running "make test" to avoid a lot of
2930 warnings about the broken locales of Mac OS X.
2932 The following tests are known to fail in Mac OS X 10.1.4 because of
2933 buggy (old) implementations of Berkeley DB included in Mac OS X:
2935 Failed Test Stat Wstat Total Fail Failed List of Failed
2936 -------------------------------------------------------------------------
2937 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2938 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2940 If you are building on a UFS partition, you will also probably see
2941 t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not
2942 supporting inode change time.
2944 Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped for
2945 now because the failure is Apple's fault, not Perl's (blocked signals
2948 If you Configure with ithreads, ext/threads/t/libc.t will fail. Again,
2949 this is not Perl's fault-- the libc of Mac OS X is not threadsafe
2950 (in this particular test, the localtime() call is found to be
2953 =head2 op/sprintf tests 91, 129, and 130
2955 The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.
2956 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2958 Test 91 is known to fail on QNX6 (nto), because C<sprintf '%e',0>
2959 incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>.
2961 For tests 129 and 130, the failing platforms do not comply with
2962 the ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, to
2963 be exact. (They produce something other than "1" and "-1" when
2964 formatting 0.6 and -0.6 using the printf format "%.0f"; most often,
2965 they produce "0" and "-0".)
2969 In case you are still using Solaris 2.5 (aka SunOS 5.5), you may
2970 experience failures (the test core dumping) in lib/locale.t.
2971 The suggested cure is to upgrade your Solaris.
2975 When Perl is built using the native build process on VOS Release
2976 14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests either
2977 pass or result in TODO (ignored) failures.
2979 =head2 Term::ReadKey not working on Win32
2981 Use Term::ReadKey 2.20 or later.
2983 =head2 Failure of Thread (5.005-style) tests
2985 B<Note that support for 5.005-style threading is deprecated,
2986 experimental and practically unsupported. In 5.10, it is expected
2989 The following tests are known to fail due to fundamental problems in
2990 the 5.005 threading implementation. These are not new failures--Perl
2991 5.005_0x has the same bugs, but didn't have these tests.
2993 ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7
2994 ../lib/English.t 2 512 54 2 3.70% 2-3
2995 ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3
2996 ../lib/Filter/Simple/t/filter_only 9 3 33.33% 1-2 5
2997 ../lib/autouse.t 10 1 10.00% 4
2998 op/flip.t 15 1 6.67% 15
3000 These failures are unlikely to get fixed as 5.005-style threads
3001 are considered fundamentally broken. (Basically what happens is that
3002 competing threads can corrupt shared global state.)
3004 =head2 Timing problems
3006 The following tests may fail intermittently because of timing
3007 problems, for example if the system is heavily loaded.
3010 ext/Time/HiRes/HiRes.t
3012 lib/Memoize/t/expmod_t.t
3013 lib/Memoize/t/speed.t
3015 In case of failure please try running them manually, for example
3017 ./perl -Ilib ext/Time/HiRes/HiRes.t
3021 ../lib/Math/Trig.t 26 1 3.85% 25
3022 ../lib/warnings.t 470 1 0.21% 429
3024 The Trig.t failure is caused by the slighly differing (from IEEE)
3025 floating point implementation of UNICOS. The warnings.t failure is
3026 also related: the test assumes a certain floating point output format;
3027 this assumption fails in UNICOS.
3035 During Configure, the test
3037 Guessing which symbols your C compiler and preprocessor define...
3039 will probably fail with error messages like
3041 CC-20 cc: ERROR File = try.c, Line = 3
3042 The identifier "bad" is undefined.
3044 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
3047 CC-65 cc: ERROR File = try.c, Line = 3
3048 A semicolon is expected at this point.
3050 This is caused by a bug in the awk utility of UNICOS/mk. You can ignore
3051 the error, but it does cause a slight problem: you cannot fully
3052 benefit from the h2ph utility (see L<h2ph>) that can be used to
3053 convert C headers to Perl libraries, mainly used to be able to access
3054 from Perl the constants defined using C preprocessor, cpp. Because of
3055 the above error, parts of the converted headers will be invisible.
3056 Luckily, these days the need for h2ph is rare.
3060 If building Perl with interpreter threads (ithreads), the
3061 getgrent(), getgrnam(), and getgrgid() functions cannot return the
3062 list of the group members due to a bug in the multithreaded support of
3063 UNICOS/mk. What this means is that in list context the functions will
3064 return only three values, not four.
3070 There are a few known test failures, see L<perluts> (README.uts).
3074 There should be no reported test failures with a default configuration,
3075 though there are a number of tests marked TODO that point to areas
3076 needing further debugging and/or porting work.
3080 In multi-CPU boxes, there are some problems with the I/O buffering:
3081 some output may appear twice.
3083 =head2 XML::Parser not working
3085 Use XML::Parser 2.31 or later.
3087 =head2 z/OS (OS/390)
3089 z/OS has rather many test failures but the situation is actually
3090 better than it was in 5.6.0; it's just that so many new modules and
3091 tests have been added.
3093 Failed Test Stat Wstat Total Fail Failed List of Failed
3094 ---------------------------------------------------------------------------
3095 ../ext/Data/Dumper/t/dumper.t 357 8 2.24% 311 314 325 327
3097 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5
3098 ../ext/Storable/t/downgrade.t 12 3072 169 12 7.10% 14-15 46-47 78-79
3100 ../lib/ExtUtils/t/Constant.t 121 30976 48 48 100.00% 1-48
3101 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9
3102 op/pat.t 910 7 0.77% 665 776 785 832-
3104 op/sprintf.t 224 3 1.34% 98 100 136
3105 op/tr.t 97 5 5.15% 63 71-74
3106 uni/fold.t 780 6 0.77% 61 169 196 661
3109 The failures in dumper.t and downgrade.t are problems in the tests,
3110 those in io_unix and sprintf are problems in the USS (UDP sockets
3111 and printf formats). The pat, tr, and fold failures are genuine Perl
3112 problems caused by EBCDIC (and in the pat and fold cases, combining
3113 that with Unicode). The Constant and Embed are probably problems
3114 in the tests (since they test Perl's ability to build extensions,
3115 and that seems to be working reasonably well.)
3117 =head2 Localising Tied Arrays and Hashes Is Broken
3121 doesn't work as one would expect: the old value is restored
3122 incorrectly. This will be changed in a future release, but we don't
3123 know yet what the new semantics will exactly be. In any case, the
3124 change will break existing code that relies on the current
3125 (ill-defined) semantics, so just avoid doing this in general.
3127 =head2 Self-tying Problems
3129 Self-tying of arrays and hashes is broken in rather deep and
3130 hard-to-fix ways. As a stop-gap measure to avoid people from getting
3131 frustrated at the mysterious results (core dumps, most often), it is
3132 forbidden for now (you will get a fatal error even from an attempt).
3134 A change to self-tying of globs has caused them to be recursively
3135 referenced (see: L<perlobj/"Two-Phased Garbage Collection">). You
3136 will now need an explicit untie to destroy a self-tied glob. This
3137 behaviour may be fixed at a later date.
3139 Self-tying of scalars and IO thingies works.
3141 =head2 Building Extensions Can Fail Because Of Largefiles
3143 Some extensions like mod_perl are known to have issues with
3144 `largefiles', a change brought by Perl 5.6.0 in which file offsets
3145 default to 64 bits wide, where supported. Modules may fail to compile
3146 at all, or they may compile and work incorrectly. Currently, there
3147 is no good solution for the problem, but Configure now provides
3148 appropriate non-largefile ccflags, ldflags, libswanted, and libs
3149 in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the
3150 extensions that are having problems can try configuring themselves
3151 without the largefileness. This is admittedly not a clean solution,
3152 and the solution may not even work at all. One potential failure is
3153 whether one can (or, if one can, whether it's a good idea to) link
3154 together at all binaries with different ideas about file offsets;
3155 all this is platform-dependent.
3157 =head2 Unicode Support on EBCDIC Still Spotty
3159 Though mostly working, Unicode support still has problem spots on
3160 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
3161 regular expression constructs for code points less than 256: the
3162 C<pP> are testing for Unicode code points, not knowing about EBCDIC.
3164 =head2 The Compiler Suite Is Still Very Experimental
3166 The compiler suite is slowly getting better but it continues to be
3167 highly experimental. Use in production environments is discouraged.
3169 =head2 The Long Double Support Is Still Experimental
3171 The ability to configure Perl's numbers to use "long doubles",
3172 floating point numbers of hopefully better accuracy, is still
3173 experimental. The implementations of long doubles are not yet
3174 widespread and the existing implementations are not quite mature
3175 or standardised, therefore trying to support them is a rare
3176 and moving target. The gain of more precision may also be offset
3177 by slowdown in computations (more bits to move around, and the
3178 operations are more likely to be executed by less optimised
3181 =head2 Seen In Perl 5.7 But Gone Now
3183 C<Time::Piece> (previously known as C<Time::Object>) was removed
3184 because it was felt that it didn't have enough value in it to be a
3185 core module. It is still a useful module, though, and is available
3188 Perl 5.8 unfortunately does not build anymore on AmigaOS;
3189 this broke accidentally at some point. Since there are not that many
3190 Amiga developers available, we could not get this fixed and tested in
3193 =head1 Reporting Bugs
3195 If you find what you think is a bug, you might check the articles
3196 recently posted to the comp.lang.perl.misc newsgroup and the perl
3197 bug database at http://bugs.perl.org/ . There may also be
3198 information at http://www.perl.com/ , the Perl Home Page.
3200 If you believe you have an unreported bug, please run the B<perlbug>
3201 program included with your release. Be sure to trim your bug down
3202 to a tiny but sufficient test case. Your bug report, along with the
3203 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3204 analysed by the Perl porting team.
3208 The F<Changes> file for exhaustive details on what changed.
3210 The F<INSTALL> file for how to build Perl.
3212 The F<README> file for general stuff.
3214 The F<Artistic> and F<Copying> files for copyright information.
3218 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.