3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release and
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
12 coordinated (while 5.8.0 was still called 5.7.something).
14 Changes that were integrated into the 5.6.1 release are marked C<[561]>.
15 Many of these changes have been further developed since 5.6.1 was released,
16 those are marked C<[561+]>.
18 You can see the list of changes in the 5.6.1 release (both from the
19 5.005_03 release and the 5.6.0 release) by reading L<perl561delta>.
21 =head1 Highlights In 5.8.0
27 Better Unicode support
31 New Thread Implementation
39 Better Numeric Accuracy
47 More Extensive Regression Testing
51 =head1 Incompatible Changes
53 =head2 Binary Incompatibility
55 B<Perl 5.8 is not binary compatible with earlier releases of Perl.>
57 B<You have to recompile your XS modules.>
59 (Pure Perl modules should continue to work.)
61 The major reason for the discontinuity is the new IO architecture
62 called PerlIO. PerlIO is the default configuration because without
63 it many new features of Perl 5.8 cannot be used. In other words:
64 you just have to recompile your modules containing XS code, sorry
67 In future releases of Perl, non-PerlIO aware XS modules may become
68 completely unsupported. This shouldn't be too difficult for module
69 authors, however: PerlIO has been designed as a drop-in replacement
70 (at the source code level) for the stdio interface.
72 Depending on your platform, there are also other reasons why
73 we decided to break binary compatibility, please read on.
75 =head2 64-bit platforms and malloc
77 If your pointers are 64 bits wide, the Perl malloc is no longer being
78 used because it does not work well with 8-byte pointers. Also,
79 usually the system mallocs on such platforms are much better optimized
80 for such large memory models than the Perl malloc. Some memory-hungry
81 Perl applications like the PDL don't work well with Perl's malloc.
82 Finally, other applications than Perl (such as mod_perl) tend to prefer
83 the system malloc. Such platforms include Alpha and 64-bit HPPA,
86 =head2 AIX Dynaloading
88 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
89 dlopen interface of AIX instead of the old emulated interface. This
90 change will probably break backward compatibility with compiled
91 modules. The change was made to make Perl more compliant with other
92 applications like mod_perl which are using the AIX native interface.
94 =head2 Attributes for C<my> variables now handled at run-time.
96 The C<my EXPR : ATTRS> syntax now applies variable attributes at
97 run-time. (Subroutine and C<our> variables still get attributes applied
98 at compile-time.) See L<attributes> for additional details. In particular,
99 however, this allows variable attributes to be useful for C<tie> interfaces,
100 which was a deficiency of earlier releases. Note that the new semantics
101 doesn't work with the Attribute::Handlers module (as of version 0.76).
103 =head2 Socket Extension Dynamic in VMS
105 The Socket extension is now dynamically loaded instead of being
106 statically built in. This may or may not be a problem with ancient
107 TCP/IP stacks of VMS: we do not know since we weren't able to test
108 Perl in such configurations.
110 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
112 Perl now uses IEEE format (T_FLOAT) as the default internal floating
113 point format on OpenVMS Alpha, potentially breaking binary compatibility
114 with external libraries or existing data. G_FLOAT is still available as
115 a configuration option. The default on VAX (D_FLOAT) has not changed.
117 =head2 New Unicode Properties
119 Unicode I<scripts> are now supported. Scripts are similar to (and superior
120 to) Unicode I<blocks>. The difference between scripts and blocks is that
121 scripts are the glyphs used by a language or a group of languages, while
122 the blocks are more artificial groupings of (mostly) 256 characters based
123 on the Unicode numbering.
125 In general, scripts are more inclusive, but not universally so. For
126 example, while the script C<Latin> includes all the Latin characters and
127 their various diacritic-adorned versions, it does not include the various
128 punctuation or digits (since they are not solely C<Latin>).
130 A number of other properties are now supported, including C<\p{L&}>,
131 C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> [561] and
132 C<\p{SpacePerl}> [561] (along with their C<\P{...}> versions, of course).
133 See L<perlunicode> for details, and more additions.
135 The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
136 are now almost always optional. The only exception is that a C<In> prefix
137 is required to signify a Unicode block when a block name conflicts with a
138 script name. For example, C<\p{Tibetan}> refers to the script, while
139 C<\p{InTibetan}> refers to the block. When there is no name conflict, you
140 can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
141 to be safe, it's probably best to always use the C<In>).
143 =head2 REF(...) Instead Of SCALAR(...)
145 A reference to a reference now stringifies as "REF(0x81485ec)" instead
146 of "SCALAR(0x81485ec)" in order to be more consistent with the return
149 =head2 pack/unpack D/F recycled
151 The undocumented pack/unpack template letters D/F have been recycled
152 for better use: now they stand for long double (if supported by the
153 platform) and NV (Perl internal floating point type). (They used
154 to be aliases for d/f, but you never knew that.)
162 The semantics of bless(REF, REF) were unclear and until someone proves
163 it to make some sense, it is forbidden.
167 The obsolete chat2 library that should never have been allowed
168 to escape the laboratory has been decommissioned.
172 The builtin dump() function has probably outlived most of its
173 usefulness. The core-dumping functionality will remain in future
174 available as an explicit call to C<CORE::dump()>, but in future
175 releases the behaviour of an unqualified C<dump()> call may change.
179 The very dusty examples in the eg/ directory have been removed.
180 Suggestions for new shiny examples welcome but the main issue is that
181 the examples need to be documented, tested and (most importantly)
186 The (bogus) escape sequences \8 and \9 now give an optional warning
187 ("Unrecognized escape passed through"). There is no need to \-escape
192 The list of filenames from glob() (or <...>) is now by default sorted
193 alphabetically to be csh-compliant (which is what happened before
194 in most UNIX platforms). (bsd_glob() does still sort platform
195 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) [561]
199 Spurious syntax errors generated in certain situations, when glob()
200 caused File::Glob to be loaded for the first time, have been fixed. [561]
204 Although "you shouldn't do that", it was possible to write code that
205 depends on Perl's hashed key order (Data::Dumper does this). The new
206 algorithm "One-at-a-Time" produces a different hashed key order.
207 More details are in L</"Performance Enhancements">.
211 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
212 In future releases this may become a fatal error.
216 The C<package;> syntax (C<package> without an argument) has been
217 deprecated. Its semantics were never that clear and its
218 implementation even less so. If you have used that feature to
219 disallow all but fully qualified variables, C<use strict;> instead.
223 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
224 recognised but now cause fatal errors. The previous behaviour of
225 ignoring them by default and warning if requested was unacceptable
226 since it, in a way, falsely promised that the features could be used.
230 In future releases, non-PerlIO aware XS modules may become completely
231 unsupported. Since PerlIO is a drop-in replacement for stdio, this
232 shouldn't be that drastic a change.
236 The current user-visible implementation of pseudo-hashes (the weird
237 use of the first array element) is deprecated starting from Perl 5.8.0
238 and will be removed in Perl 5.10.0, and the feature will be
239 implemented differently. Not only is the current interface rather
240 ugly, but the current implementation slows down normal array and hash
241 use quite noticeably. The C<fields> pragma interface will remain
242 available. The I<restricted hashes> interface is expected to
243 be the replacement interface (see L<Hash::Util>).
247 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
251 After years of trying, suidperl is considered to be too complex to
252 ever be considered truly secure. The suidperl functionality is likely
253 to be removed in a future release.
257 The 5.005 threads model (module C<Thread>) is deprecated and expected
258 to be removed in Perl 5.10. Multithreaded code should be migrated to
259 the new ithreads model (see L<threads>, L<threads::shared> and
264 The long deprecated uppercase aliases for the string comparison
265 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
269 The tr///C and tr///U features have been removed and will not return;
270 the interface was a mistake. Sorry about that. For similar
271 functionality, see pack('U0', ...) and pack('C0', ...). [561]
275 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
276 The prototypes are now checked better at compile-time for invalid
277 syntax. An optional warning is generated ("Illegal character in
278 prototype...") but this may be upgraded to a fatal error in a future
283 The C<exec LIST> and C<system LIST> will become fatal errors
284 under tainting in some future release.
288 The existing behaviour when localising tied arrays and hashes is wrong,
289 and will be changed in a future release, so do not rely on the existing
290 behaviour. See L<"Localising Tied Arrays and Hashes Is Broken">.
294 =head1 Core Enhancements
296 =head2 PerlIO is Now The Default
302 IO is now by default done via PerlIO rather than system's "stdio".
303 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
304 handle's behaviour. Layers can be specified at open time via 3-arg
307 open($fh,'>:crlf :utf8', $path) || ...
309 or on already opened handles via extended C<binmode>:
311 binmode($fh,':encoding(iso-8859-7)');
313 The built-in layers are: unix (low level read/write), stdio (as in
314 previous Perls), perlio (re-implementation of stdio buffering in a
315 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
316 but available on any platform). A mmap layer may be available if
317 platform supports it (mostly UNIXes).
319 Layers to be applied by default may be specified via the 'open' pragma.
321 See L</"Installation and Configuration Improvements"> for the effects
322 of PerlIO on your architecture name.
326 File handles can be marked as accepting Perl's internal encoding of Unicode
327 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
329 open($fh,">:utf8","Uni.txt");
331 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
332 for you since it's not UTF-8 what you will be getting but instead
333 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
334 http://www.unicode.org/unicode/reports/tr16/ for more information.
335 In future releases this naming may change.
339 File handles can translate character encodings from/to Perl's internal
340 Unicode form on read/write via the ":encoding()" layer.
344 File handles can be opened to "in memory" files held in Perl scalars via:
346 open($fh,'>', \$variable) || ...
350 Anonymous temporary files are available without need to
351 'use FileHandle' or other module via
353 open($fh,"+>", undef) || ...
355 That is a literal undef, not an undefined value.
359 The list form of C<open> is now implemented for pipes (at least on UNIX):
361 open($fh,"-|", 'cat', '/etc/motd')
363 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
368 If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG)
369 contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
370 the default encoding of your STDIN, STDOUT, and STDERR, and of
371 B<any subsequent file open>, is UTF-8.
375 =head2 Restricted Hashes
377 A restricted hash is restricted to a certain set of keys, no keys
378 outside the set can be added. Also individual keys can be restricted
379 so that the key cannot be deleted and the value cannot be changed.
380 No new syntax is involved: the Hash::Util module is the interface.
384 Perl used to be fragile in that signals arriving at inopportune moments
385 could corrupt Perl's internal state. Now Perl postpones handling of
386 signals until it's safe (between opcodes).
388 This change may have surprising side effects because signals no longer
389 interrupt Perl instantly. Perl will now first finish whatever it was
390 doing, like finishing an internal operation (like sort()) or an
391 external operation (like an I/O operation), and only then look at any
392 arrived signals (and before starting the next operation). No more corrupt
393 internal state since the current operation is always finished first,
394 but the signal may take more time to get heard. Note that breaking
395 out from potentially blocking operations should still work, though.
397 =head2 Unicode Overhaul
399 Unicode in general should be now much more usable than in Perl 5.6.0
400 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
401 regular expressions should work now, Unicode in tr/// should work now,
402 Unicode in I/O should work now. See L<perluniintro> for introduction
403 and L<perlunicode> for details.
409 The Unicode Character Database coming with Perl has been upgraded
410 to Unicode 3.2.0. For more information, see http://www.unicode.org/ .
411 [561+] (5.6.1 has UCD 3.0.1.)
415 For developers interested in enhancing Perl's Unicode capabilities:
416 almost all the UCD files are included with the Perl distribution in
417 the F<lib/unicore> subdirectory. The most notable omission, for space
418 considerations, is the Unihan database.
422 The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
423 C isblank(), that is, it contains only "horizontal whitespace" (the space
424 character is, the newline isn't), and the "SpacePerl" is the Unicode
425 equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
426 tabulator character, whereas C<\s> doesn't.)
428 See "New Unicode Properties" earlier in this document for additional
429 information on changes with Unicode properties.
433 =head2 Understanding of Numbers
435 In general a lot of fixing has happened in the area of Perl's
436 understanding of numbers, both integer and floating point. Since in
437 many systems the standard number parsing functions like C<strtoul()>
438 and C<atof()> seem to have bugs, Perl tries to work around their
439 deficiencies. This results hopefully in more accurate numbers.
441 Perl now tries internally to use integer values in numeric conversions
442 and basic arithmetics (+ - * /) if the arguments are integers, and
443 tries also to keep the results stored internally as integers.
444 This change leads to often slightly faster and always less lossy
445 arithmetics. (Previously Perl always preferred floating point numbers
448 =head2 Arrays now always interpolate into double-quoted strings [561]
450 In double-quoted strings, arrays now interpolate, no matter what. The
451 behavior in earlier versions of perl 5 was that arrays would interpolate
452 into strings if the array had been mentioned before the string was
453 compiled, and otherwise Perl would raise a fatal compile-time error.
454 In versions 5.000 through 5.003, the error was
456 Literal @example now requires backslash
458 In versions 5.004_01 through 5.6.0, the error was
460 In string, @example now must be written as \@example
462 The idea here was to get people into the habit of writing
463 C<"fred\@example.com"> when they wanted a literal C<@> sign, just as
464 they have always written C<"Give me back my \$5"> when they wanted a
467 Starting with 5.6.1, when Perl now sees an C<@> sign in a
468 double-quoted string, it I<always> attempts to interpolate an array,
469 regardless of whether or not the array has been used or declared
470 already. The fatal error has been downgraded to an optional warning:
472 Possible unintended interpolation of @example in string
474 This warns you that C<"fred@example.com"> is going to turn into
475 C<fred.com> if you don't backslash the C<@>.
476 See http://www.plover.com/~mjd/perl/at-error.html for more details
477 about the history here.
479 =head2 Miscellaneous Changes
485 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
486 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
490 The $Config{byteorder} (and corresponding BYTEORDER in config.h) was
491 previously wrong in platforms if sizeof(long) was 4, but sizeof(IV)
492 was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321),
493 but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321).
494 (This problem didn't affect Windows platforms.)
496 Also, $Config{byteorder} is now computed dynamically--this is more
497 robust with "fat binaries" where an executable image contains binaries
498 for more than one binary platform, and when cross-compiling.
502 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
503 in multiple arguments.)
507 C<do> followed by a bareword now ensures that this bareword isn't
508 a keyword (to avoid a bug where C<do q(foo.pl)> tried to call
509 subroutine called C<q>). This means that for example instead of
510 C<do format()> you must write C<do &format()>.
514 The builtin dump() now gives an optional warning
515 C<dump() better written as CORE::dump()>,
516 meaning that by default C<dump(...)> is resolved as the builtin
517 dump() which dumps core and aborts, not as (possibly) user-defined
518 C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
519 (The whole dump() feature is to considered deprecated, and possibly
520 removed/changed in future releases.)
524 chomp() and chop() are now overridable. Note, however, that their
525 prototype (as given by C<prototype("CORE::chomp")> is undefined,
526 because it cannot be expressed and therefore one cannot really write
527 replacements to override these builtins.
531 END blocks are now run even if you exit/die in a BEGIN block.
532 Internally, the execution of END blocks is now controlled by
533 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
534 behaviour for Perl embedders. This will default in 5.10. See
539 Formats now support zero-padded decimal fields.
543 Lvalue subroutines can now return C<undef> in list context. However,
544 the lvalue subroutine feature still remains experimental. [561+]
548 A lost warning "Can't declare ... dereference in my" has been
549 restored (Perl had it earlier but it became lost in later releases.)
553 A new special regular expression variable has been introduced:
554 C<$^N>, which contains the most-recently closed group (submatch).
558 C<no Module;> does not produce an error even if Module does not have an
559 unimport() method. This parallels the behavior of C<use> vis-a-vis
564 The numerical comparison operators return C<undef> if either operand
565 is a NaN. Previously the behaviour was unspecified.
569 The following builtin functions are now overridable: each(), keys(),
570 pop(), push(), shift(), splice(), unshift(). [561]
574 C<pack() / unpack()> can now group template letters with C<()> and then
575 apply repetition/count modifiers on the groups.
579 C<pack() / unpack()> can now process the Perl internal numeric types:
580 IVs, UVs, NVs-- and also long doubles, if supported by the platform.
581 The template letters are C<j>, C<J>, C<F>, and C<D>.
585 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
589 my __PACKAGE__ $obj now works. [561]
593 POSIX::sleep() now returns the number of I<unslept> seconds
594 (as the POSIX standard says), as opposed to CORE::sleep() which
595 returns the number of slept seconds.
599 The printf() and sprintf() now support parameter reordering using the
600 C<%\d+\$> and C<*\d+\$> syntaxes. For example
602 print "%2\$s %1\$s\n", "foo", "bar";
604 will print "bar foo\n". This feature helps in writing
605 internationalised software, and in general when the order
606 of the parameters can vary.
610 The (\&) prototype now works properly. [561]
614 prototype(\[$@%&]) is now available to implicitly create references
615 (useful for example if you want to emulate the tie() interface).
619 A new command-line option, C<-t> is available. It is the
620 little brother of C<-T>: instead of dying on taint violations,
621 lexical warnings are given. B<This is only meant as a temporary
622 debugging aid while securing the code of old legacy applications.
623 This is not a substitute for -T.>
627 In other taint news, the C<exec LIST> and C<system LIST> have now been
628 considered too risky (think C<exec @ARGV>: it can start any program
629 with any arguments), and now the said forms cause a warning.
630 You should carefully launder the arguments to guarantee their
631 validity. In future releases of Perl the forms will become fatal
632 errors so consider starting laundering now.
636 Tied hash interfaces are now required to have the EXISTS and DELETE
637 methods (either own or inherited).
641 If tr/// is just counting characters, it doesn't attempt to
646 untie() will now call an UNTIE() hook if it exists. See L<perltie>
651 L<utime> now supports C<utime undef, undef, @files> to change the
652 file timestamps to the current time.
656 The rules for allowing underscores (underbars) in numeric constants
657 have been relaxed and simplified: now you can have an underscore
658 simply B<between digits>.
662 Rather than relying on C's argv[0] (which may not contain a full pathname)
663 where possible $^X is now set by asking the operating system.
664 (eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD)
668 A new variable, C<${^TAINT}>, indicates whether taint mode is enabled.
672 You can now override the readline() builtin, and this overrides also
673 the <FILEHANDLE> angle bracket operator.
677 The command-line options -s and -F are now recognized on the shebang
682 Use of the C</c> match modifier without an accompanying C</g> modifier
683 elicits a new warning: C<Use of /c modifier is meaningless without /g>.
685 Use of C</c> in substitutions, even with C</g>, elicits
686 C<Use of /c modifier is meaningless in s///>.
688 Use of C</g> with C<split> elicits C<Use of /g modifier is meaningless
693 =head1 Modules and Pragmata
695 =head2 New Modules and Pragmata
701 C<Attribute::Handlers> allows a class to define attribute handlers.
704 use Attribute::Handlers;
705 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
707 # later, in some package using or inheriting from MyPack...
709 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
711 Both variables and routines can have attribute handlers. Handlers can
712 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
713 exact compilation phase (BEGIN, CHECK, INIT, or END).
714 See L<Attribute::Handlers>.
718 C<B::Concise>, by Stephen McCamant, is a new compiler backend for
719 walking the Perl syntax tree, printing concise info about ops.
720 The output is highly customisable. See L<B::Concise>. [561+]
724 The new bignum, bigint, and bigrat pragmas, by Tels, implement
725 transparent bignum support (using the Math::BigInt, Math::BigFloat,
726 and Math::BigRat backends).
730 C<Class::ISA>, by Sean Burke, is a module for reporting the search
731 path for a class's ISA tree. See L<Class::ISA>.
735 C<Cwd> now has a split personality: if possible, an XS extension is
736 used, (this will hopefully be faster, more secure, and more robust)
737 but if not possible, the familiar Perl implementation is used.
741 C<Devel::PPPort>, originally by Kenneth Albanowski and now
742 maintained by Paul Marquess, has been added. It is primarily used
743 by C<h2xs> to enhance portability of XS modules between different
744 versions of Perl. See L<Devel::PPPort>.
748 C<Digest>, frontend module for calculating digests (checksums), from
749 Gisle Aas, has been added. See L<Digest>.
753 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
754 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
756 use Digest::MD5 'md5_hex';
758 $digest = md5_hex("Thirsty Camel");
760 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
762 NOTE: the C<MD5> backward compatibility module is deliberately not
763 included since its further use is discouraged.
767 C<Encode>, originally by Nick Ing-Simmons and now maintained by Dan
768 Kogai, provides a mechanism to translate between different character
769 encodings. Support for Unicode, ISO-8859-1, and ASCII are compiled in
770 to the module. Several other encodings (like the rest of the
771 ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese,
772 Japanese, and Korean encodings) are included and can be loaded at
773 runtime. (For space considerations, the largest Chinese encodings
774 have been separated into their own CPAN module, Encode::HanExtra,
775 which Encode will use if available). See L<Encode>.
777 Any encoding supported by Encode module is also available to the
778 ":encoding()" layer if PerlIO is used.
782 C<Hash::Util> is the interface to the new I<restricted hashes>
783 feature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and
784 Michael Schwern.) See L<Hash::Util>.
788 C<I18N::Langinfo> can be used to query locale information.
789 See L<I18N::Langinfo>.
793 C<I18N::LangTags>, by Sean Burke, has functions for dealing with
794 RFC3066-style language tags. See L<I18N::LangTags>.
798 C<ExtUtils::Constant>, by Nicholas Clark, is a new tool for extension
799 writers for generating XS code to import C header constants.
800 See L<ExtUtils::Constant>.
804 C<Filter::Simple>, by Damian Conway, is an easy-to-use frontend to
805 Filter::Util::Call. See L<Filter::Simple>.
811 use Filter::Simple sub {
812 while (my ($from, $to) = splice @_, 0, 2) {
821 use MyFilter qr/red/ => 'green';
823 print "red\n"; # this code is filtered, will print "green\n"
824 print "bored\n"; # this code is filtered, will print "bogreen\n"
828 print "red\n"; # this code is not filtered, will print "red\n"
832 C<File::Temp>, by Tim Jenness, allows one to create temporary files
833 and directories in an easy, portable, and secure way. See L<File::Temp>.
838 C<Filter::Util::Call>, by Paul Marquess, provides you with the
839 framework to write I<source filters> in Perl. For most uses, the
840 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
844 C<if>, by Ilya Zakharevich, is a new pragma for conditional inclusion
849 L<libnet>, by Graham Barr, is a collection of perl5 modules related
850 to network programming. See L<Net::FTP>, L<Net::NNTP>, L<Net::Ping>
851 (not part of libnet, but related), L<Net::POP3>, L<Net::SMTP>,
854 Perl installation leaves libnet unconfigured; use F<libnetcfg>
859 C<List::Util>, by Graham Barr, is a selection of general-utility
860 list subroutines, such as sum(), min(), first(), and shuffle().
865 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>
866 C<Locale::Language>, and L<Locale::Script>, by Neil Bowers, have
867 been added. They provide the codes for various locale standards, such
868 as "fr" for France, "usd" for US Dollar, and "ja" for Japanese.
872 $country = code2country('jp'); # $country gets 'Japan'
873 $code = country2code('Norway'); # $code gets 'no'
875 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
876 and L<Locale::Language>.
880 C<Locale::Maketext>, by Sean Burke, is a localization framework. See
881 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
882 article about software localization, originally published in The Perl
883 Journal #13, and republished here with kind permission.
887 C<Math::BigRat> for big rational numbers, to accompany Math::BigInt and
888 Math::BigFloat, from Tels. See L<Math::BigRat>.
892 C<Memoize> can make your functions faster by trading space for time,
893 from Mark-Jason Dominus. See L<Memoize>.
897 C<MIME::Base64>, by Gisle Aas, allows you to encode data in base64,
898 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
903 $encoded = encode_base64('Aladdin:open sesame');
904 $decoded = decode_base64($encoded);
906 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
912 C<MIME::QuotedPrint>, by Gisle Aas, allows you to encode data
913 in quoted-printable encoding, as defined in RFC 2045 - I<MIME
914 (Multipurpose Internet Mail Extensions)>.
916 use MIME::QuotedPrint;
918 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
919 $decoded = decode_qp($encoded);
921 print $encoded, "\n"; # "Smiley in Unicode: =263A"
923 MIME::QuotedPrint has been enhanced to provide the basic methods
924 necessary to use it with PerlIO::Via as in :
926 use MIME::QuotedPrint;
927 open($fh,">Via(MIME::QuotedPrint)",$path);
929 See L<MIME::QuotedPrint>.
933 C<NEXT>, by Damian Conway, is a pseudo-class for method redispatch.
938 C<open> is a new pragma for setting the default I/O disciplines
943 C<PerlIO::Scalar>, by Nick Ing-Simmons, provides the implementation
944 of IO to "in memory" Perl scalars as discussed above. It also serves
945 as an example of a loadable PerlIO layer. Other future possibilities
946 include PerlIO::Array and PerlIO::Code. See L<PerlIO::Scalar>.
950 C<PerlIO::Via>, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
951 PerlIO layer functionality provided by a class (typically implemented
954 use MIME::QuotedPrint;
955 open($fh,">Via(MIME::QuotedPrint)",$path);
957 This will automatically convert everything output to C<$fh>
958 to Quoted-Printable. See L<PerlIO::Via>.
962 C<Pod::ParseLink>, by Russ Allbery, has been added,
963 to parse LZ<><> links in pods as described in the new
968 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
969 It converts POD data to formatted overstrike text.
970 See L<Pod::Text::Overstrike>. [561+]
974 C<Scalar::Util> is a selection of general-utility scalar subroutines,
975 such as blessed(), reftype(), and tainted(). See L<Scalar::Util>.
979 C<sort> is a new pragma for controlling the behaviour of sort().
983 C<Storable> gives persistence to Perl data structures by allowing the
984 storage and retrieval of Perl data to and from files in a fast and
985 compact binary format. Because in effect Storable does serialisation
986 of Perl data structues, with it you can also clone deep, hierarchical
987 datastructures. Storable was originally created by Raphael Manfredi,
988 but it is now maintained by Abhijit Menon-Sen. Storable has been
989 enhanced to understand the two new hash features, Unicode keys and
990 restricted hashes. See L<Storable>.
994 C<Switch>, by Damian Conway, has been added. Just by saying
998 you have C<switch> and C<case> available in Perl.
1004 case 1 { print "number 1" }
1005 case "a" { print "string a" }
1006 case [1..10,42] { print "number in list" }
1007 case (@array) { print "number in list" }
1008 case /\w+/ { print "pattern" }
1009 case qr/\w+/ { print "pattern" }
1010 case (%hash) { print "entry in hash" }
1011 case (\%hash) { print "entry in hash" }
1012 case (\&sub) { print "arg to subroutine" }
1013 else { print "previous case not true" }
1020 C<Test::More>, by Michael Schwern, is yet another framework for writing
1021 test scripts, more extensive than Test::Simple. See L<Test::More>.
1025 C<Test::Simple>, by Michael Schwern, has basic utilities for writing
1026 tests. See L<Test::Simple>.
1030 C<Text::Balanced>, by Damian Conway, has been added, for extracting
1031 delimited text sequences from strings.
1033 use Text::Balanced 'extract_delimited';
1035 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
1037 $a will be "'never say never'", $b will be ', he never said'.
1039 In addition to extract_delimited(), there are also extract_bracketed(),
1040 extract_quotelike(), extract_codeblock(), extract_variable(),
1041 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
1042 gen_extract_tagged(). With these, you can implement rather advanced
1043 parsing algorithms. See L<Text::Balanced>.
1047 C<threads>, by Arthur Bergman, is an interface to interpreter threads.
1048 Interpreter threads (ithreads) is the new thread model introduced in
1049 Perl 5.6 but only available as an internal interface for extension
1050 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>,
1051 L<threads::shared>, and L<perlthrtut>.
1055 C<threads::shared>, by Arthur Bergman, allows data sharing for
1056 interpreter threads. In the ithreads model any data sharing between
1057 threads must be explicit, as opposed to the old 5.005 thread model
1058 where data sharing was implicit. See L<threads::shared>.
1062 C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
1063 lines of a file. See L<Tie::File>.
1067 C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
1068 See L<Tie::Memoize>.
1072 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
1073 references (unlike the standard Tie::RefHash) The module is contained
1074 within Tie::RefHash. See L<Tie::RefHash>.
1078 C<Time::HiRes>, by Douglas E. Wegscheid, provides high resolution
1079 timing (ualarm, usleep, and gettimeofday). See L<Time::HiRes>.
1083 C<Unicode::UCD> offers a querying interface to the Unicode Character
1084 Database. See L<Unicode::UCD>.
1088 C<Unicode::Collate>, by SADAHIRO Tomoyuki, implements the UCA
1089 (Unicode Collation Algorithm) for sorting Unicode strings.
1090 See L<Unicode::Collate>.
1094 C<Unicode::Normalize>, by SADAHIRO Tomoyuki, implements the various
1095 Unicode normalization forms. See L<Unicode::Normalize>.
1099 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises
1100 XS typemaps. Nothing gets installed, but the code is worth studying
1101 for extension writers.
1105 =head2 Updated And Improved Modules and Pragmata
1111 The following independently supported modules have been updated to the
1112 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
1113 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
1114 (Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser, Storable,
1115 Term::ANSIColor, Test, Text-Tabs+Wrap.
1119 attributes::reftype() now works on tied arguments.
1123 AutoLoader can now be disabled with C<no AutoLoader;>.
1127 B::Deparse has been significantly enhanced by Robin Houston. It can
1128 now deparse almost all of the standard test suite (so that the tests
1129 still succeed). There is a make target "test.deparse" for trying this
1134 Carp now has better interface documentation, and the @CARP_NOT
1135 interface has been added to get optional control over where errors
1136 are reported independently of @ISA, by Ben Tilly.
1140 Class::Struct can now define the classes in compile time.
1144 Class::Struct now assigns the array/hash element if the accessor
1145 is called with an array/hash element as the B<sole> argument.
1149 The return value of Cwd::fastcwd() is now tainted.
1153 Data::Dumper now has an option to sort hashes.
1157 Data::Dumper now has an option to dump code references
1162 DB_File now supports newer Berkeley DB versions, among
1167 Devel::Peek now has an interface for the Perl memory statistics
1168 (this works only if you are using perl's malloc, and if you have
1169 compiled with debugging).
1173 The English module can now be used without the infamous performance
1176 use English '-no_match_vars';
1178 (Assuming, of course, that you don't need the troublesome variables
1179 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1180 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1184 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1185 leads to better portability.
1189 Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clark
1190 to use the new-style constant dispatch section (see L<ExtUtils::Constant>).
1191 This means that they will be more robust and hopefully faster.
1195 File::Find now chdir()s correctly when chasing symbolic links. [561]
1199 File::Find now has pre- and post-processing callbacks. It also
1200 correctly changes directories when chasing symbolic links. Callbacks
1201 (naughtily) exiting with "next;" instead of "return;" now work.
1205 File::Find is now (again) reentrant. It also has been made
1210 The warnings issued by File::Find now belong to their own category.
1211 You can enable/disable them with C<use/no warnings 'File::Find';>.
1215 File::Glob::glob() has been renamed to File::Glob::bsd_glob()
1216 because the name clashes with the builtin glob(). The older
1217 name is still available for compatibility, but is deprecated. [561]
1221 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1222 the returned list of filenames.
1226 IPC::Open3 now allows the use of numeric file descriptors.
1230 IO::Socket now has an atmark() method, which returns true if the socket
1231 is positioned at the out-of-band mark. The method is also exportable
1232 as a sockatmark() function.
1236 IO::Socket::INET failed to open the specified port if the service name
1237 was not known. It now correctly uses the supplied port number as is. [561]
1241 IO::Socket::INET has support for the ReusePort option (if your
1242 platform supports it). The Reuse option now has an alias, ReuseAddr.
1243 For clarity, you may want to prefer ReuseAddr.
1247 IO::Socket::INET now supports a value of zero for C<LocalPort>
1248 (usually meaning that the operating system will make one up.)
1252 'use lib' now works identically to @INC. Removing directories
1253 with 'no lib' now works.
1257 Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels.
1258 They are now magnitudes faster, and they support various bignum
1259 libraries such as GMP and PARI as their backends.
1263 Math::Complex handles inf, NaN etc., better.
1267 Net::Ping has been considerably enhanced by Rob Brown: multihoming is
1268 now supported, Win32 functionality is better, there is now time
1269 measuring functionality (optionally high-resolution using
1270 Time::HiRes), and there is now "external" protocol which uses
1271 Net::Ping::External module which runs your external ping utility and
1272 parses the output. A version of Net::Ping::External is available in
1275 Note that some of the Net::Ping tests are disabled when running
1276 under the Perl distribution since one cannot assume one or more
1277 of the following: enabled echo port at localhost, full Internet
1278 connectivity, or sympathetic firewalls. You can set the environment
1279 variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test
1280 suite to enable all the Net::Ping tests.
1284 POSIX::sigaction() is now much more flexible and robust.
1285 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1286 handlers, installing new handlers was not atomic.
1290 In Safe, C<%INC> is now localised in a Safe compartment so that
1295 In SDBM_File on dosish platforms, some keys went missing because of
1296 lack of support for files with "holes". A workaround for the problem
1301 In Search::Dict one can now have a pre-processing hook for the
1302 lines being searched.
1306 The Shell module now has an OO interface.
1310 In Sys::Syslog there is now a failover mechanism that will go
1311 through alternative connection mechanisms until the message
1312 is successfully logged.
1316 The Test module has been significantly enhanced.
1320 Time::Local::timelocal() does not handle fractional seconds anymore.
1321 The rationale is that neither does localtime(), and timelocal() and
1322 localtime() are supposed to be inverses of each other.
1326 The vars pragma now supports declaring fully qualified variables.
1327 (Something that C<our()> does not and will not support.)
1331 The C<utf8::> name space (as in the pragma) provides various
1332 Perl-callable functions to provide low level access to Perl's
1333 internal Unicode representation. At the moment only length()
1334 has been implemented.
1338 =head1 Utility Changes
1344 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1349 F<emacs/e2ctags.pl> is now much faster.
1353 C<enc2xs> is a tool for people adding their own encodings to the
1358 C<h2ph> now supports C trigraphs.
1362 C<h2xs> now produces a template README.
1366 C<h2xs> now uses C<Devel::PPPort> for better portability between
1367 different versions of Perl.
1371 C<h2xs> uses the new L<ExtUtils::Constant|ExtUtils::Constant> module
1372 which will affect newly created extensions that define constants.
1373 Since the new code is more correct (if you have two constants where the
1374 first one is a prefix of the second one, the first constant B<never>
1375 got defined), less lossy (it uses integers for integer constant,
1376 as opposed to the old code that used floating point numbers even for
1377 integer constants), and slightly faster, you might want to consider
1378 regenerating your extension code (the new scheme makes regenerating
1379 easy). L<h2xs> now also supports C trigraphs.
1383 C<libnetcfg> has been added to configure libnet.
1387 C<perlbug> is now much more robust. It also sends the bug report to
1388 perl.org, not perl.com.
1392 C<perlcc> has been rewritten and its user interface (that is,
1393 command line) is much more like that of the UNIX C compiler, cc.
1394 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1395 B<Note that perlcc is still considered very experimental and
1400 C<perlivp> is a new Installation Verification Procedure utility
1401 for running any time after installing Perl.
1405 C<piconv> is an implementation of the character conversion utility
1406 C<iconv>, demonstrating the new Encode module.
1410 C<pod2html> now allows specifying a cache directory.
1414 C<pod2html> now produces XHTML 1.0.
1418 C<pod2html> now understands POD written using different line endings
1419 (PC-like CRLF versus UNIX-like LF versus MacClassic-like CR).
1423 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1424 implementation of sed in Perl: you can use the sed functionality by
1425 using the C<psed> utility.)
1429 C<xsubpp> now understands POD documentation embedded in the *.xs
1434 C<xsubpp> now supports the OUT keyword.
1438 =head1 New Documentation
1444 perl56delta details the changes between the 5.005 release and the
1449 perlclib documents the internal replacements for standard C library
1450 functions. (Interesting only for extension writers and Perl core
1455 perldebtut is a Perl debugging tutorial. [561+]
1459 perlebcdic contains considerations for running Perl on EBCDIC
1464 perlintro is a gentle introduction to Perl.
1468 perliol documents the internals of PerlIO with layers.
1472 perlmodstyle is a style guide for writing modules.
1476 perlnewmod tells about writing and submitting a new module. [561+]
1480 perlpacktut is a pack() tutorial.
1484 perlpod has been rewritten to be clearer and to record the best
1485 practices gathered over the years.
1489 perlpodspec is a more formal specification of the pod format,
1490 mainly of interest for writers of pod applications, not to
1491 people writing in pod.
1495 perlretut is a regular expression tutorial. [561+]
1499 perlrequick is a regular expressions quick-start guide.
1500 Yes, much quicker than perlretut. [561]
1504 perltodo has been updated.
1508 perltootc has been renamed as perltooc (to not to conflict
1509 with perltoot in filesystems restricted to "8.3" names).
1513 perluniintro is an introduction to using Unicode in Perl.
1514 (perlunicode is more of a detailed reference and background
1519 perlutil explains the command line utilities packaged with the Perl
1520 distribution. [561+]
1524 The following platform-specific documents are available before
1525 the installation as README.I<platform>, and after the installation
1528 perlaix perlamiga perlapollo perlbeos perlbs2000
1529 perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux
1530 perlhurd perlmachten perlmacos perlmint perlmpeix
1531 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1532 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1534 These documents usually detail one or more of the following subjects:
1535 configuring, building, testing, installing, and sometimes also using
1536 Perl on the said platform.
1538 Eastern Asian Perl users are now welcomed in their own languages:
1539 README.jp (Japanese), README.ko (Korean), README.cn (simplified
1540 Chinese) and README.tw (traditional Chinese), which are written in
1541 normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These
1542 will get installed as
1544 perljp perlko perlcn perltw
1550 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1551 confusion with the Perl POSIX module.
1555 The documentation for the WinCE platform is called perlce (README.ce
1556 in the source code kit), to avoid confusion with the perlwin32
1557 documentation on 8.3-restricted filesystems.
1561 =head1 Performance Enhancements
1567 map() could get pathologically slow when the result list it generates
1568 is larger than the source list. The performance has been improved for
1569 common scenarios. [561]
1573 sort() is also fully reentrant, in the sense that the sort function
1574 can itself call sort(). This did not work reliably in previous
1579 sort() has been changed to use primarily mergesort internally as
1580 opposed to the earlier quicksort. For very small lists this may
1581 result in slightly slower sorting times, but in general the speedup
1582 should be at least 20%. Additional bonuses are that the worst case
1583 behaviour of sort() is now better (in computer science terms it now
1584 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1585 worst-case run time behaviour), and that sort() is now stable
1586 (meaning that elements with identical keys will stay ordered as they
1587 were before the sort). See the C<sort> pragma for information.
1589 The story in more detail: suppose you want to serve yourself a little
1592 @digits = ( 3,1,4,1,5,9 );
1594 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1595 Which C<1> comes first is hard to know, since one C<1> looks pretty
1596 much like any other. You can regard this as totally trivial,
1597 or somewhat profound. However, if you just want to sort the even
1598 digits ahead of the odd ones, then what will
1600 sort { ($a % 2) <=> ($b % 2) } @digits;
1602 yield? The only even digit, C<4>, will come first. But how about
1603 the odd numbers, which all compare equal? With the quicksort algorithm
1604 used to implement Perl 5.6 and earlier, the order of ties is left up
1605 to the sort. So, as you add more and more digits of Pi, the order
1606 in which the sorted even and odd digits appear will change.
1607 and, for sufficiently large slices of Pi, the quicksort algorithm
1608 in Perl 5.8 won't return the same results even if reinvoked with the
1609 same input. The justification for this rests with quicksort's
1610 worst case behavior. If you run
1612 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1614 (something you might approximate if you wanted to merge two sorted
1615 arrays using sort), doubling $N doesn't just double the quicksort time,
1616 it I<quadruples> it. Quicksort has a worst case run time that can
1617 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1618 on patterns that may well arise in normal use. You won't notice this
1619 for small arrays, but you I<will> notice it with larger arrays,
1620 and you may not live long enough for the sort to complete on arrays
1621 of a million elements. So the 5.8 quicksort scrambles large arrays
1622 before sorting them, as a statistical defence against quadratic behaviour.
1623 But that means if you sort the same large array twice, ties may be
1624 broken in different ways.
1626 Because of the unpredictability of tie-breaking order, and the quadratic
1627 worst-case behaviour, quicksort was I<almost> replaced completely with
1628 a stable mergesort. I<Stable> means that ties are broken to preserve
1629 the original order of appearance in the input array. So
1631 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1633 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1634 appear in the output in the same order they appeared in the input.
1635 Mergesort has worst case O(N log N) behaviour, the best value
1636 attainable. And, ironically, this mergesort does particularly
1637 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1638 in O(N) time. But quicksort was rescued at the last moment because
1639 it is faster than mergesort on certain inputs and platforms.
1640 For example, if you really I<don't> care about the order of even
1641 and odd digits, quicksort will run in O(N) time; it's very good
1642 at sorting many repetitions of a small number of distinct elements.
1643 The quicksort divide and conquer strategy works well on platforms
1644 with relatively small, very fast, caches. Eventually, the problem gets
1645 whittled down to one that fits in the cache, from which point it
1646 benefits from the increased memory speed.
1648 Quicksort was rescued by implementing a sort pragma to control aspects
1649 of the sort. The B<stable> subpragma forces stable behaviour,
1650 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1651 subpragmas are heavy-handed ways to select the underlying implementation.
1652 The leading C<_> is a reminder that these subpragmas may not survive
1653 beyond 5.8. More appropriate mechanisms for selecting the implementation
1654 exist, but they wouldn't have arrived in time to save quicksort.
1658 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1659 ( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is
1660 reasonably fast while producing a much better spread of values than
1661 the old hashing algorithm (originally by Chris Torek, later tweaked by
1662 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1663 all 3-char printable ASCII keys comes much closer to passing the
1664 DIEHARD random number generation tests. According to perlbench, this
1665 change has not affected the overall speed of Perl.
1669 unshift() should now be noticeably faster.
1673 =head1 Installation and Configuration Improvements
1675 =head2 Generic Improvements
1681 INSTALL now explains how you can configure Perl to use 64-bit
1682 integers even on non-64-bit platforms.
1686 Policy.sh policy change: if you are reusing a Policy.sh file
1687 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1688 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1689 them will now be changed to the new prefix, /foo/bar. (Previously
1690 only $prefix changed.) If you do not like this new behaviour,
1691 specify prefix, siteprefix, and vendorprefix explicitly.
1695 A new optional location for Perl libraries, otherlibdirs, is available.
1696 It can be used for example for vendor add-ons without disturbing Perl's
1697 own library directories.
1701 In many platforms, the vendor-supplied 'cc' is too stripped-down to
1702 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1703 to be the case and 'cc' does not seem to be the GNU C compiler
1704 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1708 gcc needs to closely track the operating system release to avoid
1709 build problems. If Configure finds that gcc was built for a different
1710 operating system release than is running, it now gives a clearly visible
1711 warning that there may be trouble ahead.
1715 Since Perl 5.8 is not binary-compatible with previous releases
1716 of Perl, Configure no longer suggests including the 5.005
1721 Configure C<-S> can now run non-interactively. [561]
1725 Configure support for pdp11-style memory models has been removed due
1726 to obsolescence. [561]
1730 configure.gnu now works with options with whitespace in them.
1734 installperl now outputs everything to STDERR.
1738 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1739 get appended to the $Config{archname} (also known as $^O) anymore.
1740 Instead, if you explicitly choose not to use perlio (Configure command
1741 line option -Uuseperlio), you will get "-stdio" appended.
1745 Another change related to the architecture name is that "-64all"
1746 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1747 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1751 In AFS installations, one can configure the root of the AFS to be
1752 somewhere else than the default F</afs> by using the Configure
1753 parameter C<-Dafsroot=/some/where/else>.
1757 APPLLIB_EXP, a lesser-known configuration-time definition, has been
1758 documented. It can be used to prepend site-specific directories
1759 to Perl's default search path (@INC); see INSTALL for information.
1763 The version of Berkeley DB used when the Perl (and, presumably, the
1764 DB_File extension) was built is now available as
1765 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1766 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1767 DB_VERSION_PATCH_CFG> from C.
1771 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1772 has been documented in INSTALL.
1776 If you have CPAN access (either network or a local copy such as a
1777 CD-ROM) you can during specify extra modules to Configure to build and
1778 install with Perl using the -Dextras=... option. See INSTALL for
1783 In addition to config.over, a new override file, config.arch, is
1784 available. This file is supposed to be used by hints file writers
1785 for architecture-wide changes (as opposed to config.over which is
1786 for site-wide changes).
1790 If your file system supports symbolic links, you can build Perl outside
1791 of the source directory by
1793 mkdir /tmp/perl/build/directory
1794 cd /tmp/perl/build/directory
1795 sh /path/to/perl/source/Configure -Dmksymlinks ...
1797 This will create in /tmp/perl/build/directory a tree of symbolic links
1798 pointing to files in /path/to/perl/source. The original files are left
1799 unaffected. After Configure has finished, you can just say
1803 and Perl will be built and tested, all in /tmp/perl/build/directory.
1808 For Perl developers, several new make targets for profiling
1809 and debugging have been added; see L<perlhack>.
1815 Use of the F<gprof> tool to profile Perl has been documented in
1816 L<perlhack>. There is a make target called "perl.gprof" for
1817 generating a gprofiled Perl executable.
1821 If you have GCC 3, there is a make target called "perl.gcov" for
1822 creating a gcoved Perl executable for coverage analysis. See
1827 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1828 have been added; see L<perlhack> for more information about pixie and
1835 Guidelines of how to construct minimal Perl installations have
1836 been added to INSTALL.
1840 The Thread extension is now not built at all under ithreads
1841 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1842 Thread extension requires being Configured with C<-Duse5005threads>).
1844 But note that the Thread.pm interface is now shared by both
1849 The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
1850 floating-point numbers is now more picky about using sprintf %.*g
1851 rules for the conversion. Some platforms that used to use gcvt may
1852 now resort to the slower sprintf.
1856 The obsolete method of making a special (e.g., debugging) flavor
1859 make LIBPERL=libperld.a
1861 has been removed. Use -DDEBUGGING instead.
1865 =head2 New Or Improved Platforms
1867 For the list of platforms known to support Perl,
1868 see L<perlport/"Supported Platforms">.
1874 AIX dynamic loading should be now better supported.
1878 AIX should now work better with gcc, threads, and 64-bitness. Also the
1879 long doubles support in AIX should be better now. See L<perlaix>.
1883 AtheOS ( http://www.atheos.cx/ ) is a new platform.
1887 BeOS has been reclaimed.
1891 The DG/UX platform now supports 5.005-style threads.
1896 The DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near
1901 EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA)
1902 have been regained. Many test suite tests still fail and the
1903 co-existence of Unicode and EBCDIC isn't quite settled, but the
1904 situation is much better than with Perl 5.6. See L<perlos390>,
1905 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1909 Building perl with -Duseithreads or -Duse5005threads now works under
1910 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1911 need a thread library package installed. See README.hpux. [561]
1915 Mac OS Classic is now supported in the mainstream source package
1916 (MacPerl has of course been available since perl 5.004 but now the
1917 source code bases of standard Perl and MacPerl have been synchronised)
1922 Mac OS X (or Darwin) should now be able to build Perl even on HFS+
1923 filesystems. (The case-insensitivity used to confuse the Perl build
1928 NCR MP-RAS is now supported. [561]
1932 All the NetBSD specific patches (except for the installation
1933 specific ones) have been merged back to the main distribution.
1937 NetWare from Novell is now supported. See L<perlnetware>.
1941 NonStop-UX is now supported. [561]
1945 NEC SUPER-UX is now supported.
1949 All the OpenBSD specific patches (except for the installation
1950 specific ones) have been merged back to the main distribution.
1954 Perl has been tested with the GNU pth userlevel thread package
1955 ( http://www.gnu.org/software/pth/pth.html ). All thread tests
1956 of Perl now work, but not without adding some yield()s to the tests,
1957 so while pth (and other userlevel thread implementations) can be
1958 considered to be "working" with Perl ithreads, keep in mind the
1959 possible non-preemptability of the underlying thread implementation.
1963 Stratus VOS is now supported using Perl's native build method
1964 (Configure). This is the recommended method to build Perl on
1965 VOS. The older methods, which build miniperl, are still
1966 available. See L<perlvos>. [561+]
1970 The Amdahl UTS UNIX mainframe platform is now supported. [561]
1974 WinCE is now supported. See L<perlce>.
1978 z/OS (formerly known as OS/390, formerly known as MVS OE) now has
1979 support for dynamic loading. This is not selected by default,
1980 however, you must specify -Dusedl in the arguments of Configure. [561]
1984 =head1 Selected Bug Fixes
1986 Numerous memory leaks and uninitialized memory accesses have been
1987 hunted down. Most importantly, anonymous subs used to leak quite
1994 The autouse pragma didn't work for Multi::Part::Function::Names.
1998 caller() could cause core dumps in certain situations. Carp was
1999 sometimes affected by this problem. In particular, caller() now
2000 returns a subroutine name of C<(unknown)> for subroutines that have
2001 been removed from the symbol table.
2005 chop(@list) in list context returned the characters chopped in
2006 reverse order. This has been reversed to be in the right order. [561]
2010 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
2011 when building the Perl binary. The only exception to this is SunOS 4.x,
2012 which needs them. [561]
2016 The behaviour of non-decimal but numeric string constants such as
2017 "0x23" was platform-dependent: in some platforms that was seen as 35,
2018 in some as 0, in some as a floating point number (don't ask). This
2019 was caused by Perl's using the operating system libraries in a situation
2020 where the result of the string to number conversion is undefined: now
2021 Perl consistently handles such strings as zero in numeric contexts.
2025 The order of DESTROYs has been made more predictable.
2029 Several debugger fixes: exit code now reflects the script exit code,
2030 condition C<"0"> now treated correctly, the C<d> command now checks
2031 line number, C<$.> no longer gets corrupted, and all debugger output
2032 now goes correctly to the socket if RemotePort is set. [561]
2036 Perl 5.6.0 could emit spurious warnings about redefinition of
2037 dl_error() when statically building extensions into perl.
2038 This has been corrected. [561]
2042 L<dprofpp> -R didn't work.
2046 C<*foo{FORMAT}> now works.
2050 Infinity is now recognized as a number.
2054 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
2055 the Tk extension with 5.6.0.) [561]
2059 Lexicals I: lexicals outside an eval "" weren't resolved
2060 correctly inside a subroutine definition inside the eval "" if they
2061 were not already referenced in the top level of the eval""ed code.
2065 Lexicals II: lexicals leaked at file scope into subroutines that
2066 were declared before the lexicals.
2070 Lexical warnings now propagating correctly between scopes
2071 and into C<eval "...">.
2075 C<use warnings qw(FATAL all)> did not work as intended. This has been
2080 warnings::enabled() now reports the state of $^W correctly if the caller
2081 isn't using lexical warnings. [561]
2085 Line renumbering with eval and C<#line> now works. [561]
2089 Fixed numerous memory leaks, especially in eval "".
2093 Localised tied variables no longer leak memory
2096 tie my %tied_hash => 'Tie::StdHash';
2100 # Used to leak memory every time local() was called;
2101 # in a loop, this added up.
2102 local($tied_hash{Foo}) = 1;
2106 Localised hash elements (and %ENV) are correctly unlocalised to not
2107 exist, if they didn't before they were localised.
2111 tie my %tied_hash => 'Tie::StdHash';
2115 # Nothing has set the FOO element so far
2117 { local $tied_hash{FOO} = 'Bar' }
2119 # This used to print, but not now.
2120 print "exists!\n" if exists $tied_hash{FOO};
2122 As a side effect of this fix, tied hash interfaces B<must> define
2123 the EXISTS and DELETE methods.
2127 mkdir() now ignores trailing slashes in the directory name,
2128 as mandated by POSIX.
2132 Some versions of glibc have a broken modfl(). This affects builds
2133 with C<-Duselongdouble>. This version of Perl detects this brokenness
2134 and has a workaround for it. The glibc release 2.2.2 is known to have
2135 fixed the modfl() bug.
2139 Modulus of unsigned numbers now works (4063328477 % 65535 used to
2140 return 27406, instead of 27047). [561]
2144 Some "not a number" warnings introduced in 5.6.0 eliminated to be
2145 more compatible with 5.005. Infinity is now recognised as a number. [561]
2149 Numeric conversions did not recognize changes in the string value
2150 properly in certain circumstances. [561]
2154 Attributes (such as :shared) didn't work with our().
2158 our() variables will not cause bogus "Variable will not stay shared"
2163 "our" variables of the same name declared in two sibling blocks
2164 resulted in bogus warnings about "redeclaration" of the variables.
2165 The problem has been corrected. [561]
2169 pack "Z" now correctly terminates the string with "\0".
2173 Fix password routines which in some shadow password platforms
2174 (e.g. HP-UX) caused getpwent() to return every other entry.
2178 The PERL5OPT environment variable (for passing command line arguments
2179 to Perl) didn't work for more than a single group of options. [561]
2183 PERL5OPT with embedded spaces didn't work.
2187 printf() no longer resets the numeric locale to "C".
2191 C<qw(a\\b)> now parses correctly as C<'a\\b'>: that is, as three
2192 characters, not four. [561]
2196 pos() did not return the correct value within s///ge in earlier
2197 versions. This is now handled correctly. [561]
2201 Printing quads (64-bit integers) with printf/sprintf now works
2202 without the q L ll prefixes (assuming you are on a quad-capable platform).
2206 Regular expressions on references and overloaded scalars now work. [561+]
2210 Right-hand side magic (GMAGIC) could in many cases such as string
2211 concatenation be invoked too many times.
2215 scalar() now forces scalar context even when used in void context.
2219 SOCKS support is now much more robust.
2223 sort() arguments are now compiled in the right wantarray context
2224 (they were accidentally using the context of the sort() itself).
2225 The comparison block is now run in scalar context, and the arguments
2226 to be sorted are always provided list context. [561]
2230 Changed the POSIX character class C<[[:space:]]> to include the (very
2231 rarely used) vertical tab character. Added a new POSIX-ish character
2232 class C<[[:blank:]]> which stands for horizontal whitespace
2233 (currently, the space and the tab).
2237 The tainting behaviour of sprintf() has been rationalized. It does
2238 not taint the result of floating point formats anymore, making the
2239 behaviour consistent with that of string interpolation. [561]
2243 Some cases of inconsistent taint propagation (such as within hash
2244 values) have been fixed.
2248 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
2249 of simple pattern matches. These are now handled better. [561]
2253 Regular expression debug output (whether through C<use re 'debug'>
2254 or via C<-Dr>) now looks better. [561]
2258 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
2259 bug has been fixed. [561]
2263 Use of $& could trigger a core dump under some situations. This
2264 is now avoided. [561]
2268 The regular expression captured submatches ($1, $2, ...) are now
2269 more consistently unset if the match fails, instead of leaving false
2270 data lying around in them. [561]
2274 readline() on files opened in "slurp" mode could return an extra
2275 "" (blank line) at the end in certain situations. This has been
2280 Autovivification of symbolic references of special variables described
2281 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
2286 Sys::Syslog ignored the C<LOG_AUTH> constant.
2290 All but the first argument of the IO syswrite() method are now optional.
2294 $AUTOLOAD, sort(), lock(), and spawning subprocesses
2295 in multiple threads simultaneously are now thread-safe.
2299 Tie::Array's SPLICE method was broken.
2303 Allow a read-only string on the left-hand side of a non-modifying tr///.
2307 If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
2308 correctly pass to it.
2312 Several Unicode fixes.
2318 BOMs (byte order marks) at the beginning of Perl files
2319 (scripts, modules) should now be transparently skipped.
2320 UTF-16 and UCS-2 encoded Perl files should now be read correctly.
2324 The character tables have been updated to Unicode 3.2.0.
2328 Comparing with utf8 data does not magically upgrade non-utf8 data
2329 into utf8. (This was a problem for example if you were mixing data
2330 from I/O and Unicode data: your output might have got magically encoded
2335 Generating illegal Unicode code points such as U+FFFE, or the UTF-16
2336 surrogates, now also generates an optional warning.
2340 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2344 Concatenation with the C<.> operator or via variable interpolation,
2345 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2346 substitution with C<s///>, single-quoted UTF8, should now work.
2350 The C<tr///> operator now works. Note that the C<tr///CU>
2351 functionality has been removed (but see pack('U0', ...)).
2355 C<eval "v200"> now works.
2359 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2360 This has been corrected. [561]
2364 Zero entries were missing from the Unicode classes such as C<IsDigit>.
2370 Large unsigned numbers (those above 2**31) could sometimes lose their
2371 unsignedness, causing bogus results in arithmetic operations. [561]
2375 The Perl parser has been stress tested using both random input and
2376 Markov chain input and the few found crashes and lockups have been
2381 =head2 Platform Specific Changes and Fixes
2389 Perl now works on post-4.0 BSD/OSes.
2395 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2401 Numerous updates; currently synchronised with Cygwin 1.3.10.
2405 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2411 EPOC now better supported. See README.epoc. [561]
2417 Perl now works on post-3.0 FreeBSDs.
2423 README.hpux updated; C<Configure -Duse64bitall> now works;
2424 now uses HP-UX malloc instead of Perl malloc.
2430 Numerous compilation flag and hint enhancements; accidental mixing
2431 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2441 Long doubles should now work (see INSTALL). [561]
2445 Linux previously had problems related to sockaddrlen when using
2446 accept(), recvfrom() (in Perl: recv()), getpeername(), and
2455 Compilation of the standard Perl distribution in Mac OS Classic should
2456 now work if you have the Metrowerks development environment and the
2457 missing Mac-specific toolkit bits. Contact the macperl mailing list
2464 MPE/iX update after Perl 5.6.0. See README.mpeix. [561]
2468 NetBSD/threads: try installing the GNU pth (should be in the
2469 packages collection, or http://www.gnu.org/software/pth/),
2470 and Configure with -Duseithreads.
2476 Perl now works on NetBSD/sparc.
2482 Now works with usethreads (see INSTALL). [561]
2488 64-bitness using the Sun Workshop compiler now works.
2494 The native build method requires at least VOS Release 14.5.0
2495 and GNU C++/GNU Tools 2.0.1 or later. The Perl pack function
2496 now maps overflowed values to +infinity and underflowed values
2501 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2503 The operating system version letter now recorded in $Config{osvers}.
2504 Allow compiling with gcc (previously explicitly forbidden). Compiling
2505 with gcc still not recommended because buggy code results, even with
2512 Fixed various alignment problems that lead into core dumps either
2513 during build or later; no longer dies on math errors at runtime;
2514 now using full quad integers (64 bits), previously was using
2515 only 46 bit integers for speed.
2521 See L</"Socket Extension Dynamic in VMS"> and L</"IEEE-format Floating Point
2522 Default on OpenVMS Alpha"> for important changes not otherwise listed here.
2524 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2525 (see INSTALL); now works with Perl's malloc.
2527 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2528 unimplemented. It now works as documented.
2530 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2531 was that a pid of -1 would cause a wildcard search of all processes on
2534 POSIX-style signals are now emulated much better on VMS versions prior
2537 The C<system> function and backticks operator have improved
2538 functionality and better error handling. [561]
2540 File access tests now use current process privileges rather than the
2541 user's default privileges, which could sometimes result in a mismatch
2542 between reported access and actual access.
2544 There is a new C<kill> implementation based on C<sys$sigprc> that allows
2545 older VMS systems (pre-7.0) to use C<kill> to send signals rather than
2546 simply force exit. This implementation also allows later systems to
2547 call C<kill> from within a signal handler.
2549 Iterative logical name translations are now limited to 10 iterations in
2550 imitation of SHOW LOGICAL and other OpenVMS facilities.
2560 accept() no longer leaks memory. [561]
2564 Borland C++ v5.5 is now a supported compiler that can build Perl.
2565 However, the generated binaries continue to be incompatible with those
2566 generated by the other supported compilers (GCC and Visual C++). [561]
2570 Better chdir() return value for a non-existent directory.
2574 Duping socket handles with open(F, ">&MYSOCK") now works under Windows
2579 New %ENV entries now propagate to subprocesses. [561]
2583 Current directory entries in %ENV are now correctly propagated to child
2588 $ENV{LIB} now used to search for libs under Visual C.
2592 fork() emulation has been improved in various ways, but still continues
2593 to be experimental. See L<perlfork> for known bugs and caveats. [561+]
2597 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
2601 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2602 Other bugs in chdir() and Cwd::cwd() have also been fixed. [561]
2606 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2610 The makefiles now provide a single switch to bulk-enable all the
2611 features enabled in ActiveState ActivePerl (a popular Win32 binary
2612 distribution). [561]
2616 Allow REG_EXPAND_SZ keys in the registry.
2620 Can now send() from all threads, not just the first one. [561]
2624 ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries.
2628 Fake signal handling reenabled, bugs and all.
2632 %SIG has been enabled under USE_ITHREADS, but its use is completely
2633 unsupported under all configurations. [561]
2637 Less stack reserved per thread so that more threads can run
2638 concurrently. (Still 16M per thread.)
2642 C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
2643 (works better when perl is running as service).
2647 Better UNC path handling under ithreads. [561]
2651 wait(), waitpid(), and backticks now return the correct exit status
2652 under Windows 9x. [561]
2656 Non-blocking waits for child processes (or pseudo-processes) are
2657 supported via C<waitpid($pid, &POSIX::WNOHANG)>.
2661 Win64 compilation is now supported.
2665 winsock handle leak fixed. [561]
2671 =head1 New or Changed Diagnostics
2677 The lexical warnings category "deprecated" is no longer a sub-category
2678 of the "syntax" category. It is now a top-level category in its own
2683 All regular expression compilation error messages are now hopefully
2684 easier to understand both because the error message now comes before
2685 the failed regex and because the point of failure is now clearly
2686 marked by a C<E<lt>-- HERE> marker.
2690 The various "opened only for", "on closed", "never opened" warnings
2691 drop the C<main::> prefix for filehandles in the C<main> package,
2692 for example C<STDIN> instead of C<main::STDIN>.
2696 The "Unrecognized escape" warning has been extended to include C<\8>,
2697 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2701 Two new debugging options have been added: if you have compiled your
2702 Perl with debugging, you can use the -DT [561] and -DR options to trace
2703 tokenising and to add reference counts to displaying variables,
2708 The debugger (perl5db.pl) has been modified to present a more
2709 consistent commands interface, via (CommandSet=580). perl5db.t was
2710 also added to test the changes, and as a placeholder for further tests.
2716 The debugger has a new C<dumpDepth> option to control the maximum
2717 depth to which nested structures are dumped. The C<x> command has
2718 been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a
2719 depth of at most I<N> levels.
2723 The debugger can now show lexical variables if you have the CPAN
2724 module PadWalker installed.
2728 If an attempt to use a (non-blessed) reference as an array index
2729 is made, a warning is given.
2733 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2734 now give a warning. This may be a problem for generated and evaled
2739 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2740 using the C<"C"> format you will get an optional warning. Similarly
2741 for the C<"c"> format and a number less than -128 or more than 127.
2745 Certain regex modifiers such as C<(?o)> make sense only if applied to
2746 the entire regex. You will get an optional warning if you try to do
2751 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2752 has been deprecated for a while. Now you will get an optional warning.
2756 Using C<sort> in scalar context now issues an optional warning.
2757 This didn't do anything useful, as the sort was not performed.
2761 =head1 Changed Internals
2767 perlapi.pod (a companion to perlguts) now attempts to document the
2772 You can now build a really minimal perl called microperl.
2773 Building microperl does not require even running Configure;
2774 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2775 many assumptions, some of which may be too bold; the resulting
2776 executable may crash or otherwise misbehave in wondrous ways.
2777 For careful hackers only.
2781 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2782 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2783 interfaces to the publicised API. For the full list of the available
2784 APIs see L<perlapi>.
2788 Made possible to propagate customised exceptions via croak()ing.
2792 Now xsubs can have attributes just like subs. (Well, at least the
2793 built-in attributes.)
2797 dTHR and djSP have been obsoleted; the former removed (because it's
2798 a no-op) and the latter replaced with dSP.
2802 PERL_OBJECT has been completely removed.
2806 The MAGIC constants (e.g. C<'P'>) have been macrofied
2807 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2808 and maintainability.
2812 The regex compiler now maintains a structure that identifies nodes in
2813 the compiled bytecode with the corresponding syntactic features of the
2814 original regex expression. The information is attached to the new
2815 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2816 complete information.
2820 The C code has been made much more C<gcc -Wall> clean. Some warning
2821 messages still remain in some platforms, so if you are compiling with
2822 gcc you may see some warnings about dubious practices. The warnings
2823 are being worked on.
2827 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2831 Documentation on how to use the Perl source repository has been added
2832 to F<Porting/repository.pod>.
2836 There are now several profiling make targets.
2840 =head1 Security Vulnerability Closed [561]
2842 (This change was already made in 5.7.0 but bears repeating here.)
2844 A potential security vulnerability in the optional suidperl component
2845 of Perl was identified in August 2000. suidperl is neither built nor
2846 installed by default. As of November 2001 the only known vulnerable
2847 platform is Linux, most likely all Linux distributions. CERT and
2848 various vendors and distributors have been alerted about the vulnerability.
2849 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2850 for more information.
2852 The problem was caused by Perl trying to report a suspected security
2853 exploit attempt using an external program, /bin/mail. On Linux
2854 platforms the /bin/mail program had an undocumented feature which
2855 when combined with suidperl gave access to a root shell, resulting in
2856 a serious compromise instead of reporting the exploit attempt. If you
2857 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2858 suidperl is not installed, you are safe.
2860 The exploit attempt reporting feature has been completely removed from
2861 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2862 from all the Perl 5.7 releases), so that particular vulnerability
2863 isn't there anymore. However, further security vulnerabilities are,
2864 unfortunately, always possible. The suidperl functionality is most
2865 probably going to be removed in Perl 5.10. In any case, suidperl
2866 should only be used by security experts who know exactly what they are
2867 doing and why they are using suidperl instead of some other solution
2868 such as sudo ( see http://www.courtesan.com/sudo/ ).
2872 Several new tests have been added, especially for the F<lib> and F<ext>
2873 subsections. There are now about 65 000 individual tests (spread over
2874 about 700 test scripts), in the regression suite (5.6.1 has about
2875 11700 tests, in 258 test scripts) Many of the new tests are of course
2876 introduced by the new modules, but still in general Perl is now more
2879 Because of the large number of tests, running the regression suite
2880 will take considerably longer time than it used to: expect the suite
2881 to take up to 4-5 times longer to run than in perl 5.6. On a really
2882 fast machine you can hope to finish the suite in about 6-8 minutes
2885 The tests are now reported in a different order than in earlier Perls.
2886 (This happens because the test scripts from under t/lib have been moved
2887 to be closer to the library/extension they are testing.)
2889 =head1 Known Problems
2897 If using the AIX native make command, instead of just "make" issue
2898 "make all". In some setups the former has been known to spuriously
2899 also try to run "make install". Alternatively, you may want to use
2904 In AIX 4.2, Perl extensions that use C++ functions that use statics
2905 may have problems in that the statics are not getting initialized.
2906 In newer AIX releases, this has been solved by linking Perl with
2907 the libC_r library, but unfortunately in AIX 4.2 the said library
2908 has an obscure bug where the various functions related to time
2909 (such as time() and gettimeofday()) return broken values, and
2910 therefore in AIX 4.2 Perl is not linked against libC_r.
2914 vac 5.0.0.0 May Produce Buggy Code For Perl
2916 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2917 resulting in a few random tests failing when run as part of "make
2918 test", but when the failing tests are run by hand, they succeed.
2919 We suggest upgrading to at least vac version 5.0.1.0, that has been
2920 known to compile Perl correctly. "lslpp -L|grep vac.C" will tell
2921 you the vac version. See README.aix.
2925 If building threaded Perl, you may get compilation warning from pp_sys.c:
2927 "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
2929 This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()
2930 having slightly different types for their first argument.
2934 =head2 Alpha systems with old gccs fail several tests
2936 If you see op/pack, op/pat, op/regexp, or ext/Storable tests failing
2937 in a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc.
2938 gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 may
2939 be even better. (RedHat Linux/alpha with gcc 3.1 reported no problems,
2940 as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable to
2941 use the bundled C compiler.)
2945 Perl 5.8.0 doesn't build in AmigaOS. It broke at some point during
2946 the ithreads work and we could not find Amiga experts to unbreak the
2947 problems. Perl 5.6.1 still works for AmigaOS (as does the the 5.7.2
2948 development release).
2952 The following tests fail on 5.8.0 Perl in BeOS Personal 5.03:
2954 t/op/lfs............................FAILED at test 17
2955 t/op/magic..........................FAILED at test 24
2956 ext/POSIX/t/sigaction...............FAILED at test 13
2957 ext/POSIX/t/waitpid.................FAILED at test 1
2959 See L<perlbeos> (README.beos) for more details.
2961 =head2 Cygwin "unable to remap"
2963 For example when building the Tk extension for Cygwin,
2964 you may get an error message saying "unable to remap".
2965 This is known problem with Cygwin, and a workaround is
2966 detailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html
2968 =head2 ext/threads/t/libc
2970 If this test fails, it indicates that your libc (C library) is not
2971 threadsafe. This particular test stress tests the localtime() call to
2972 find out whether it is threadsafe. See L<perlthrtut> for more information.
2974 =head2 FreeBSD built with ithreads coredumps reading large directories
2976 This is a known bug in FreeBSD's readdir_r() (see L<perlfreebsd>
2977 (README.freebsd)), which hopefully will be fixed in FreeBSD 4.6.
2979 =head2 FreeBSD Failing locale Test 117 For ISO8859-15 Locales
2981 The ISO8859-15 locales may fail the locale test 117 in FreeBSD.
2982 This is caused by the characters \xFF (y with diaeresis) and \xBE
2983 (Y with diaeresis) not behaving correctly when being matched
2986 =head2 IRIX fails ext/List/Util/t/shuffle.t
2988 IRIX with MIPSpro 7.3.1.3m compiler may fail the said List::Util test
2989 by dumping core. This seems to be a compiler error since if compiled
2990 with gcc no core dump ensues, and no failures on the said test on any
2993 =head2 Modifying $_ Inside for(..)
2997 works without complaint. It shouldn't. (You should be able to
2998 modify only lvalue elements inside the loops.) You can see the
2999 correct behaviour by replacing the 1..5 with 1, 2, 3, 4, 5.
3001 =head2 mod_perl 1.26 Doesn't Build With Threaded Perl
3003 Use mod_perl 1.27 or higher.
3005 =head2 lib/ftmp-security tests warn 'system possibly insecure'
3007 Don't panic. Read the 'make test' section of INSTALL instead.
3009 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
3011 If perl is configured with -Duse64bitall, the successful result of the
3012 subtest 10 of lib/posix may arrive before the successful result of the
3013 subtest 9, which confuses the test harness so much that it thinks the
3016 =head2 Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint
3018 This is a known bug in the glibc 2.2.5 with long long integers.
3019 ( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )
3021 =head2 Linux With Sfio Fails op/misc Test 48
3025 =head2 libwww-perl (LWP) fails base/date #51
3027 Use libwww-perl 5.65 or later.
3031 Please remember to set your environment variable LC_ALL to "C"
3032 (setenv LC_ALL C) before running "make test" to avoid a lot of
3033 warnings about the broken locales of Mac OS X.
3035 The following tests are known to fail in Mac OS X 10.1.5 because of
3036 buggy (old) implementations of Berkeley DB included in Mac OS X:
3038 Failed Test Stat Wstat Total Fail Failed List of Failed
3039 -------------------------------------------------------------------------
3040 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
3041 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
3043 If you are building on a UFS partition, you will also probably see
3044 t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not
3045 supporting inode change time.
3047 Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped for
3048 now because the failure is Apple's fault, not Perl's (blocked signals
3051 If you Configure with ithreads, ext/threads/t/libc.t will fail. Again,
3052 this is not Perl's fault-- the libc of Mac OS X is not threadsafe
3053 (in this particular test, the localtime() call is found to be
3056 =head2 op/sprintf tests 91, 129, and 130
3058 The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.
3059 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
3061 Test 91 is known to fail on QNX6 (nto), because C<sprintf '%e',0>
3062 incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>.
3064 For tests 129 and 130, the failing platforms do not comply with
3065 the ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, to
3066 be exact. (They produce something other than "1" and "-1" when
3067 formatting 0.6 and -0.6 using the printf format "%.0f"; most often,
3068 they produce "0" and "-0".)
3072 In case you are still using Solaris 2.5 (aka SunOS 5.5), you may
3073 experience failures (the test core dumping) in lib/locale.t.
3074 The suggested cure is to upgrade your Solaris.
3076 =head2 SUPER-UX (NEC SX)
3078 The following tests are known to fail on SUPER-UX:
3080 op/64bitint...........................FAILED tests 29-30, 32-33, 35-36
3081 op/arith..............................FAILED tests 128-130
3082 op/pack...............................FAILED tests 25-5625
3083 op/pow................................
3084 op/taint..............................# msgsnd failed
3085 ../ext/IO/lib/IO/t/io_poll............FAILED tests 3-4
3086 ../ext/IPC/SysV/ipcsysv...............FAILED tests 2, 5-6
3087 ../ext/IPC/SysV/t/msg.................FAILED tests 2, 4-6
3088 ../ext/Socket/socketpair..............FAILED tests 12
3089 ../lib/IPC/SysV.......................FAILED tests 2, 5-6
3090 ../lib/warnings.......................FAILED tests 115-116, 118-119
3092 The op/pack failure ("Cannot compress negative numbers at op/pack.t line 126")
3093 is serious but as of yet unsolved. It points at some problems with the
3094 signedness handling of the C compiler, as do the 64bitint, arith, and pow
3095 failures. Most of the rest point at problems with SysV IPC.
3097 =head2 Term::ReadKey not working on Win32
3099 Use Term::ReadKey 2.20 or later.
3101 =head2 Failure of Thread (5.005-style) tests
3103 B<Note that support for 5.005-style threading is deprecated,
3104 experimental and practically unsupported. In 5.10, it is expected
3107 The following tests are known to fail due to fundamental problems in
3108 the 5.005 threading implementation. These are not new failures--Perl
3109 5.005_0x has the same bugs, but didn't have these tests.
3111 ../ext/B/t/xref.t 255 65280 14 12 85.71% 3-14
3112 ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7
3113 ../lib/English.t 2 512 54 2 3.70% 2-3
3114 ../lib/ExtUtils/t/basic.t 1 256 17 1 5.88% 14
3115 ../lib/FileCache.t 5 1 20.00% 5
3116 ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3
3117 ../lib/Filter/Simple/t/filter_onl 9 3 33.33% 1-2 5
3118 ../lib/Tie/File/t/31_autodefer.t 255 65280 65 32 49.23% 34-65
3119 ../lib/autouse.t 10 1 10.00% 4
3120 op/flip.t 15 1 6.67% 15
3122 These failures are unlikely to get fixed as 5.005-style threads
3123 are considered fundamentally broken. (Basically what happens is that
3124 competing threads can corrupt shared global state.)
3126 =head2 Timing problems
3128 The following tests may fail intermittently because of timing
3129 problems, for example if the system is heavily loaded.
3132 ext/Time/HiRes/HiRes.t
3134 lib/Memoize/t/expmod_t.t
3135 lib/Memoize/t/speed.t
3137 In case of failure please try running them manually, for example
3139 ./perl -Ilib ext/Time/HiRes/HiRes.t
3143 ../lib/Math/Trig.t 26 1 3.85% 25
3144 ../lib/warnings.t 470 1 0.21% 429
3146 The Trig.t failure is caused by the slighly differing (from IEEE)
3147 floating point implementation of UNICOS. The warnings.t failure is
3148 also related: the test assumes a certain floating point output format;
3149 this assumption fails in UNICOS.
3157 During Configure, the test
3159 Guessing which symbols your C compiler and preprocessor define...
3161 will probably fail with error messages like
3163 CC-20 cc: ERROR File = try.c, Line = 3
3164 The identifier "bad" is undefined.
3166 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
3169 CC-65 cc: ERROR File = try.c, Line = 3
3170 A semicolon is expected at this point.
3172 This is caused by a bug in the awk utility of UNICOS/mk. You can ignore
3173 the error, but it does cause a slight problem: you cannot fully
3174 benefit from the h2ph utility (see L<h2ph>) that can be used to
3175 convert C headers to Perl libraries, mainly used to be able to access
3176 from Perl the constants defined using C preprocessor, cpp. Because of
3177 the above error, parts of the converted headers will be invisible.
3178 Luckily, these days the need for h2ph is rare.
3182 If building Perl with interpreter threads (ithreads), the
3183 getgrent(), getgrnam(), and getgrgid() functions cannot return the
3184 list of the group members due to a bug in the multithreaded support of
3185 UNICOS/mk. What this means is that in list context the functions will
3186 return only three values, not four.
3192 There are a few known test failures, see L<perluts> (README.uts).
3194 =head2 VOS (Stratus)
3196 When Perl is built using the native build process on VOS Release
3197 14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests either
3198 pass or result in TODO (ignored) failures.
3202 There should be no reported test failures with a default configuration,
3203 though there are a number of tests marked TODO that point to areas
3204 needing further debugging and/or porting work.
3208 In multi-CPU boxes, there are some problems with the I/O buffering:
3209 some output may appear twice.
3211 =head2 XML::Parser not working
3213 Use XML::Parser 2.31 or later.
3215 =head2 z/OS (OS/390)
3217 z/OS has rather many test failures but the situation is actually
3218 better than it was in 5.6.0; it's just that so many new modules and
3219 tests have been added.
3221 Failed Test Stat Wstat Total Fail Failed List of Failed
3222 ---------------------------------------------------------------------------
3223 ../ext/Data/Dumper/t/dumper.t 357 8 2.24% 311 314 325 327
3225 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5
3226 ../ext/Storable/t/downgrade.t 12 3072 169 12 7.10% 14-15 46-47 78-79
3228 ../lib/ExtUtils/t/Constant.t 121 30976 48 48 100.00% 1-48
3229 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9
3230 op/pat.t 910 7 0.77% 665 776 785 832-
3232 op/sprintf.t 224 3 1.34% 98 100 136
3233 op/tr.t 97 5 5.15% 63 71-74
3234 uni/fold.t 780 6 0.77% 61 169 196 661
3237 The failures in dumper.t and downgrade.t are problems in the tests,
3238 those in io_unix and sprintf are problems in the USS (UDP sockets
3239 and printf formats). The pat, tr, and fold failures are genuine Perl
3240 problems caused by EBCDIC (and in the pat and fold cases, combining
3241 that with Unicode). The Constant and Embed are probably problems
3242 in the tests (since they test Perl's ability to build extensions,
3243 and that seems to be working reasonably well.)
3245 =head2 Localising Tied Arrays and Hashes Is Broken
3249 doesn't work as one would expect: the old value is restored
3250 incorrectly. This will be changed in a future release, but we don't
3251 know yet what the new semantics will exactly be. In any case, the
3252 change will break existing code that relies on the current
3253 (ill-defined) semantics, so just avoid doing this in general.
3255 =head2 Self-tying Problems
3257 Self-tying of arrays and hashes is broken in rather deep and
3258 hard-to-fix ways. As a stop-gap measure to avoid people from getting
3259 frustrated at the mysterious results (core dumps, most often), it is
3260 forbidden for now (you will get a fatal error even from an attempt).
3262 A change to self-tying of globs has caused them to be recursively
3263 referenced (see: L<perlobj/"Two-Phased Garbage Collection">). You
3264 will now need an explicit untie to destroy a self-tied glob. This
3265 behaviour may be fixed at a later date.
3267 Self-tying of scalars and IO thingies works.
3269 =head2 Building Extensions Can Fail Because Of Largefiles
3271 Some extensions like mod_perl are known to have issues with
3272 `largefiles', a change brought by Perl 5.6.0 in which file offsets
3273 default to 64 bits wide, where supported. Modules may fail to compile
3274 at all, or they may compile and work incorrectly. Currently, there
3275 is no good solution for the problem, but Configure now provides
3276 appropriate non-largefile ccflags, ldflags, libswanted, and libs
3277 in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the
3278 extensions that are having problems can try configuring themselves
3279 without the largefileness. This is admittedly not a clean solution,
3280 and the solution may not even work at all. One potential failure is
3281 whether one can (or, if one can, whether it's a good idea to) link
3282 together at all binaries with different ideas about file offsets;
3283 all this is platform-dependent.
3285 =head2 Unicode Support on EBCDIC Still Spotty
3287 Though mostly working, Unicode support still has problem spots on
3288 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
3289 regular expression constructs for code points less than 256: the
3290 C<pP> are testing for Unicode code points, not knowing about EBCDIC.
3292 =head2 The Compiler Suite Is Still Very Experimental
3294 The compiler suite is slowly getting better but it continues to be
3295 highly experimental. Use in production environments is discouraged.
3297 =head2 The Long Double Support Is Still Experimental
3299 The ability to configure Perl's numbers to use "long doubles",
3300 floating point numbers of hopefully better accuracy, is still
3301 experimental. The implementations of long doubles are not yet
3302 widespread and the existing implementations are not quite mature
3303 or standardised, therefore trying to support them is a rare
3304 and moving target. The gain of more precision may also be offset
3305 by slowdown in computations (more bits to move around, and the
3306 operations are more likely to be executed by less optimised
3309 =head2 Seen In Perl 5.7 But Gone Now
3311 C<Time::Piece> (previously known as C<Time::Object>) was removed
3312 because it was felt that it didn't have enough value in it to be a
3313 core module. It is still a useful module, though, and is available
3316 Perl 5.8 unfortunately does not build anymore on AmigaOS; this broke
3317 accidentally at some point. Since there are not that many Amiga
3318 developers available, we could not get this fixed and tested in time
3319 for 5.8.0. Perl 5.6.1 still works for AmigaOS (as does the the 5.7.2
3320 development release).
3322 =head1 Reporting Bugs
3324 If you find what you think is a bug, you might check the articles
3325 recently posted to the comp.lang.perl.misc newsgroup and the perl
3326 bug database at http://bugs.perl.org/ . There may also be
3327 information at http://www.perl.com/ , the Perl Home Page.
3329 If you believe you have an unreported bug, please run the B<perlbug>
3330 program included with your release. Be sure to trim your bug down
3331 to a tiny but sufficient test case. Your bug report, along with the
3332 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3333 analysed by the Perl porting team.
3337 The F<Changes> file for exhaustive details on what changed.
3339 The F<INSTALL> file for how to build Perl.
3341 The F<README> file for general stuff.
3343 The F<Artistic> and F<Copying> files for copyright information.
3347 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.