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
35 New Thread Implementation
39 Better Numeric Accuracy
51 More Extensive Regression Testing
55 =head1 Incompatible Changes
57 =head2 Binary Incompatibility
59 B<Perl 5.8 is not binary compatible with earlier releases of Perl.>
61 B<You have to recompile your XS modules.>
63 (Pure Perl modules should continue to work.)
65 The major reason for the discontinuity is the new IO architecture
66 called PerlIO. PerlIO is the default configuration because without
67 it many new features of Perl 5.8 cannot be used. In other words:
68 you just have to recompile your modules containing XS code, sorry
71 In future releases of Perl, non-PerlIO aware XS modules may become
72 completely unsupported. This shouldn't be too difficult for module
73 authors, however: PerlIO has been designed as a drop-in replacement
74 (at the source code level) for the stdio interface.
76 Depending on your platform, there are also other reasons why
77 we decided to break binary compatibility, please read on.
79 =head2 64-bit platforms and malloc
81 If your pointers are 64 bits wide, the Perl malloc is no longer being
82 used because it does not work well with 8-byte pointers. Also,
83 usually the system mallocs on such platforms are much better optimized
84 for such large memory models than the Perl malloc. Some memory-hungry
85 Perl applications like the PDL don't work well with Perl's malloc.
86 Finally, other applications than Perl (such as mod_perl) tend to prefer
87 the system malloc. Such platforms include Alpha and 64-bit HPPA,
90 =head2 AIX Dynaloading
92 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
93 dlopen interface of AIX instead of the old emulated interface. This
94 change will probably break backward compatibility with compiled
95 modules. The change was made to make Perl more compliant with other
96 applications like mod_perl which are using the AIX native interface.
98 =head2 Attributes for C<my> variables now handled at run-time.
100 The C<my EXPR : ATTRS> syntax now applies variable attributes at
101 run-time. (Subroutine and C<our> variables still get attributes applied
102 at compile-time.) See L<attributes> for additional details. In particular,
103 however, this allows variable attributes to be useful for C<tie> interfaces,
104 which was a deficiency of earlier releases. Note that the new semantics
105 doesn't work with the Attribute::Handlers module (as of version 0.76).
107 =head2 Socket Extension Dynamic in VMS
109 The Socket extension is now dynamically loaded instead of being
110 statically built in. This may or may not be a problem with ancient
111 TCP/IP stacks of VMS: we do not know since we weren't able to test
112 Perl in such configurations.
114 =head2 IEEE-format Floating Point Default on OpenVMS Alpha
116 Perl now uses IEEE format (T_FLOAT) as the default internal floating
117 point format on OpenVMS Alpha, potentially breaking binary compatibility
118 with external libraries or existing data. G_FLOAT is still available as
119 a configuration option. The default on VAX (D_FLOAT) has not changed.
121 =head2 New Unicode Properties
123 Unicode I<scripts> are now supported. Scripts are similar to (and superior
124 to) Unicode I<blocks>. The difference between scripts and blocks is that
125 scripts are the glyphs used by a language or a group of languages, while
126 the blocks are more artificial groupings of (mostly) 256 characters based
127 on the Unicode numbering.
129 In general, scripts are more inclusive, but not universally so. For
130 example, while the script C<Latin> includes all the Latin characters and
131 their various diacritic-adorned versions, it does not include the various
132 punctuation or digits (since they are not solely C<Latin>).
134 A number of other properties are now supported, including C<\p{L&}>,
135 C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> [561] and
136 C<\p{SpacePerl}> [561] (along with their C<\P{...}> versions, of course).
137 See L<perlunicode> for details, and more additions.
139 The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
140 are now almost always optional. The only exception is that a C<In> prefix
141 is required to signify a Unicode block when a block name conflicts with a
142 script name. For example, C<\p{Tibetan}> refers to the script, while
143 C<\p{InTibetan}> refers to the block. When there is no name conflict, you
144 can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
145 to be safe, it's probably best to always use the C<In>).
147 =head2 REF(...) Instead Of SCALAR(...)
149 A reference to a reference now stringifies as "REF(0x81485ec)" instead
150 of "SCALAR(0x81485ec)" in order to be more consistent with the return
153 =head2 pack/unpack D/F recycled
155 The undocumented pack/unpack template letters D/F have been recycled
156 for better use: now they stand for long double (if supported by the
157 platform) and NV (Perl internal floating point type). (They used
158 to be aliases for d/f, but you never knew that.)
166 The semantics of bless(REF, REF) were unclear and until someone proves
167 it to make some sense, it is forbidden.
171 The obsolete chat2 library that should never have been allowed
172 to escape the laboratory has been decommissioned.
176 The builtin dump() function has probably outlived most of its
177 usefulness. The core-dumping functionality will remain in future
178 available as an explicit call to C<CORE::dump()>, but in future
179 releases the behaviour of an unqualified C<dump()> call may change.
183 The very dusty examples in the eg/ directory have been removed.
184 Suggestions for new shiny examples welcome but the main issue is that
185 the examples need to be documented, tested and (most importantly)
190 The (bogus) escape sequences \8 and \9 now give an optional warning
191 ("Unrecognized escape passed through"). There is no need to \-escape
196 The list of filenames from glob() (or <...>) is now by default sorted
197 alphabetically to be csh-compliant (which is what happened before
198 in most UNIX platforms). (bsd_glob() does still sort platform
199 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) [561]
203 Spurious syntax errors generated in certain situations, when glob()
204 caused File::Glob to be loaded for the first time, have been fixed. [561]
208 Although "you shouldn't do that", it was possible to write code that
209 depends on Perl's hashed key order (Data::Dumper does this). The new
210 algorithm "One-at-a-Time" produces a different hashed key order.
211 More details are in L</"Performance Enhancements">.
215 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
216 In future releases this may become a fatal error.
220 The C<package;> syntax (C<package> without an argument) has been
221 deprecated. Its semantics were never that clear and its
222 implementation even less so. If you have used that feature to
223 disallow all but fully qualified variables, C<use strict;> instead.
227 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
228 recognised but now cause fatal errors. The previous behaviour of
229 ignoring them by default and warning if requested was unacceptable
230 since it, in a way, falsely promised that the features could be used.
234 In future releases, non-PerlIO aware XS modules may become completely
235 unsupported. Since PerlIO is a drop-in replacement for stdio at the
236 source code level, this shouldn't be that drastic a change.
240 Previous versions of perl and some readings of some sections of Camel III
241 implied that the C<:raw> "discipline" was the inverse of C<:crlf>.
242 Turning off "clrfness" is no longer enough to make a stream truly
243 binary. So the PerlIO C<:raw> layer (or "discipline", to use the
244 Camel book's older terminology) is now formally defined as being
245 equivalent to binmode(FH) - which is in turn defined as doing whatever
246 is necessary to pass each byte as-is without any translation.
247 In particular binmode(FH) - and hence C<:raw> - will now turn off both CRLF
248 and UTF-8 translation and remove other layers (e.g. :encoding()) which
249 would modify byte stream.
253 The current user-visible implementation of pseudo-hashes (the weird
254 use of the first array element) is deprecated starting from Perl 5.8.0
255 and will be removed in Perl 5.10.0, and the feature will be
256 implemented differently. Not only is the current interface rather
257 ugly, but the current implementation slows down normal array and hash
258 use quite noticeably. The C<fields> pragma interface will remain
259 available. The I<restricted hashes> interface is expected to
260 be the replacement interface (see L<Hash::Util>). If your existing
261 programs depends on the underlying implementation, consider using
262 L<Class::PseudoHash> from CPAN.
266 The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
270 After years of trying, suidperl is considered to be too complex to
271 ever be considered truly secure. The suidperl functionality is likely
272 to be removed in a future release.
276 The 5.005 threads model (module C<Thread>) is deprecated and expected
277 to be removed in Perl 5.10. Multithreaded code should be migrated to
278 the new ithreads model (see L<threads>, L<threads::shared> and
283 The long deprecated uppercase aliases for the string comparison
284 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
288 The tr///C and tr///U features have been removed and will not return;
289 the interface was a mistake. Sorry about that. For similar
290 functionality, see pack('U0', ...) and pack('C0', ...). [561]
294 Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
295 The prototypes are now checked better at compile-time for invalid
296 syntax. An optional warning is generated ("Illegal character in
297 prototype...") but this may be upgraded to a fatal error in a future
302 The C<exec LIST> and C<system LIST> operations will produce fatal
303 errors on tainted data in some future release.
307 The existing behaviour when localising tied arrays and hashes is wrong,
308 and will be changed in a future release, so do not rely on the existing
309 behaviour. See L<"Localising Tied Arrays and Hashes Is Broken">.
313 =head1 Core Enhancements
315 =head2 PerlIO is Now The Default
321 IO is now by default done via PerlIO rather than system's "stdio".
322 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
323 handle's behaviour. Layers can be specified at open time via 3-arg
326 open($fh,'>:crlf :utf8', $path) || ...
328 or on already opened handles via extended C<binmode>:
330 binmode($fh,':encoding(iso-8859-7)');
332 The built-in layers are: unix (low level read/write), stdio (as in
333 previous Perls), perlio (re-implementation of stdio buffering in a
334 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
335 but available on any platform). A mmap layer may be available if
336 platform supports it (mostly UNIXes).
338 Layers to be applied by default may be specified via the 'open' pragma.
340 See L</"Installation and Configuration Improvements"> for the effects
341 of PerlIO on your architecture name.
345 If your platform supports fork(), you can use the list form of C<open>
346 for pipes. For example:
348 open KID_PS, "-|", "ps", "aux" or die $!;
350 forks the ps(1) command (without spawning a shell, as there are more
351 than three arguments to open()), and reads its standard output via the
352 C<KID_PS> filehandle. See L<perlipc>.
356 File handles can be marked as accepting Perl's internal encoding of Unicode
357 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
359 open($fh,">:utf8","Uni.txt");
361 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
362 for you since it's not UTF-8 what you will be getting but instead
363 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
364 http://www.unicode.org/unicode/reports/tr16/ for more information.
365 In future releases this naming may change. See L<perluniintro>
366 for more information about UTF-8.
370 If your environment variables (LC_ALL, LC_CTYPE, LANG, LANGUAGE) look
371 like you want to use UTF-8 (any of the the variables match C</utf-?8/i>),
372 your STDIN, STDOUT, STDERR handles and the default open layer
373 (see L<open>) are marked as UTF-8. (This feature, like other new
374 features that combine Unicode and I/O, work only if you are using
375 PerlIO, but that's the default.)
377 Note that after this Perl really does assume that everything is UTF-8:
378 for example if some input handle is not, Perl will probably very soon
379 complain about the input data like this "Malformed UTF-8 ..." since
380 any old eight-bit data is not legal UTF-8.
382 Note for code authors: if you want to enable your users to use UTF-8
383 as their default encoding but in your code still have eight-bit I/O streams
384 (such as images or zip files), you need to explicitly open() or binmode()
385 with C<:bytes> (see L<perlfunc/open> and L<perlfunc/binmode>), or you
386 can just use C<binmode(FH)> (nice for pre-5.8.0 backward compatibility).
390 File handles can translate character encodings from/to Perl's internal
391 Unicode form on read/write via the ":encoding()" layer.
395 File handles can be opened to "in memory" files held in Perl scalars via:
397 open($fh,'>', \$variable) || ...
401 Anonymous temporary files are available without need to
402 'use FileHandle' or other module via
404 open($fh,"+>", undef) || ...
406 That is a literal undef, not an undefined value.
410 The list form of C<open> is now implemented for pipes (at least on UNIX):
412 open($fh,"-|", 'cat', '/etc/motd')
414 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
419 If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG)
420 contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
421 the default encoding of your STDIN, STDOUT, and STDERR, and of
422 B<any subsequent file open>, is UTF-8.
426 =head2 Restricted Hashes
428 A restricted hash is restricted to a certain set of keys, no keys
429 outside the set can be added. Also individual keys can be restricted
430 so that the key cannot be deleted and the value cannot be changed.
431 No new syntax is involved: the Hash::Util module is the interface.
435 Perl used to be fragile in that signals arriving at inopportune moments
436 could corrupt Perl's internal state. Now Perl postpones handling of
437 signals until it's safe (between opcodes).
439 This change may have surprising side effects because signals no longer
440 interrupt Perl instantly. Perl will now first finish whatever it was
441 doing, like finishing an internal operation (like sort()) or an
442 external operation (like an I/O operation), and only then look at any
443 arrived signals (and before starting the next operation). No more corrupt
444 internal state since the current operation is always finished first,
445 but the signal may take more time to get heard. Note that breaking
446 out from potentially blocking operations should still work, though.
448 =head2 Unicode Overhaul
450 Unicode in general should be now much more usable than in Perl 5.6.0
451 (or even in 5.6.1). Unicode can be used in hash keys, Unicode in
452 regular expressions should work now, Unicode in tr/// should work now,
453 Unicode in I/O should work now. See L<perluniintro> for introduction
454 and L<perlunicode> for details.
460 The Unicode Character Database coming with Perl has been upgraded
461 to Unicode 3.2.0. For more information, see http://www.unicode.org/ .
462 [561+] (5.6.1 has UCD 3.0.1.)
466 For developers interested in enhancing Perl's Unicode capabilities:
467 almost all the UCD files are included with the Perl distribution in
468 the F<lib/unicore> subdirectory. The most notable omission, for space
469 considerations, is the Unihan database.
473 The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
474 C isblank(), that is, it contains only "horizontal whitespace" (the space
475 character is, the newline isn't), and the "SpacePerl" is the Unicode
476 equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
477 tabulator character, whereas C<\s> doesn't.)
479 See "New Unicode Properties" earlier in this document for additional
480 information on changes with Unicode properties.
484 =head2 Understanding of Numbers
486 In general a lot of fixing has happened in the area of Perl's
487 understanding of numbers, both integer and floating point. Since in
488 many systems the standard number parsing functions like C<strtoul()>
489 and C<atof()> seem to have bugs, Perl tries to work around their
490 deficiencies. This results hopefully in more accurate numbers.
492 Perl now tries internally to use integer values in numeric conversions
493 and basic arithmetics (+ - * /) if the arguments are integers, and
494 tries also to keep the results stored internally as integers.
495 This change leads to often slightly faster and always less lossy
496 arithmetics. (Previously Perl always preferred floating point numbers
499 =head2 Arrays now always interpolate into double-quoted strings [561]
501 In double-quoted strings, arrays now interpolate, no matter what. The
502 behavior in earlier versions of perl 5 was that arrays would interpolate
503 into strings if the array had been mentioned before the string was
504 compiled, and otherwise Perl would raise a fatal compile-time error.
505 In versions 5.000 through 5.003, the error was
507 Literal @example now requires backslash
509 In versions 5.004_01 through 5.6.0, the error was
511 In string, @example now must be written as \@example
513 The idea here was to get people into the habit of writing
514 C<"fred\@example.com"> when they wanted a literal C<@> sign, just as
515 they have always written C<"Give me back my \$5"> when they wanted a
518 Starting with 5.6.1, when Perl now sees an C<@> sign in a
519 double-quoted string, it I<always> attempts to interpolate an array,
520 regardless of whether or not the array has been used or declared
521 already. The fatal error has been downgraded to an optional warning:
523 Possible unintended interpolation of @example in string
525 This warns you that C<"fred@example.com"> is going to turn into
526 C<fred.com> if you don't backslash the C<@>.
527 See http://www.plover.com/~mjd/perl/at-error.html for more details
528 about the history here.
530 =head2 Miscellaneous Changes
536 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
537 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
541 The $Config{byteorder} (and corresponding BYTEORDER in config.h) was
542 previously wrong in platforms if sizeof(long) was 4, but sizeof(IV)
543 was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321),
544 but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321).
545 (This problem didn't affect Windows platforms.)
547 Also, $Config{byteorder} is now computed dynamically--this is more
548 robust with "fat binaries" where an executable image contains binaries
549 for more than one binary platform, and when cross-compiling.
553 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
554 in multiple arguments.)
558 C<do> followed by a bareword now ensures that this bareword isn't
559 a keyword (to avoid a bug where C<do q(foo.pl)> tried to call a
560 subroutine called C<q>). This means that for example instead of
561 C<do format()> you must write C<do &format()>.
565 The builtin dump() now gives an optional warning
566 C<dump() better written as CORE::dump()>,
567 meaning that by default C<dump(...)> is resolved as the builtin
568 dump() which dumps core and aborts, not as (possibly) user-defined
569 C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
570 (The whole dump() feature is to considered deprecated, and possibly
571 removed/changed in future releases.)
575 chomp() and chop() are now overridable. Note, however, that their
576 prototype (as given by C<prototype("CORE::chomp")> is undefined,
577 because it cannot be expressed and therefore one cannot really write
578 replacements to override these builtins.
582 END blocks are now run even if you exit/die in a BEGIN block.
583 Internally, the execution of END blocks is now controlled by
584 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
585 behaviour for Perl embedders. This will default in 5.10. See
590 Formats now support zero-padded decimal fields.
594 Lvalue subroutines can now return C<undef> in list context. However,
595 the lvalue subroutine feature still remains experimental. [561+]
599 A lost warning "Can't declare ... dereference in my" has been
600 restored (Perl had it earlier but it became lost in later releases.)
604 A new special regular expression variable has been introduced:
605 C<$^N>, which contains the most-recently closed group (submatch).
609 C<no Module;> does not produce an error even if Module does not have an
610 unimport() method. This parallels the behavior of C<use> vis-a-vis
615 The numerical comparison operators return C<undef> if either operand
616 is a NaN. Previously the behaviour was unspecified.
620 C<our> can now have an experimental optional attribute C<unique> that
621 affects how global variables are shared among multiple interpreters,
626 The following builtin functions are now overridable: each(), keys(),
627 pop(), push(), shift(), splice(), unshift(). [561]
631 C<pack() / unpack()> can now group template letters with C<()> and then
632 apply repetition/count modifiers on the groups.
636 C<pack() / unpack()> can now process the Perl internal numeric types:
637 IVs, UVs, NVs-- and also long doubles, if supported by the platform.
638 The template letters are C<j>, C<J>, C<F>, and C<D>.
642 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
646 my __PACKAGE__ $obj now works. [561]
650 POSIX::sleep() now returns the number of I<unslept> seconds
651 (as the POSIX standard says), as opposed to CORE::sleep() which
652 returns the number of slept seconds.
656 The printf() and sprintf() now support parameter reordering using the
657 C<%\d+\$> and C<*\d+\$> syntaxes. For example
659 print "%2\$s %1\$s\n", "foo", "bar";
661 will print "bar foo\n". This feature helps in writing
662 internationalised software, and in general when the order
663 of the parameters can vary.
667 The (\&) prototype now works properly. [561]
671 prototype(\[$@%&]) is now available to implicitly create references
672 (useful for example if you want to emulate the tie() interface).
676 A new command-line option, C<-t> is available. It is the
677 little brother of C<-T>: instead of dying on taint violations,
678 lexical warnings are given. B<This is only meant as a temporary
679 debugging aid while securing the code of old legacy applications.
680 This is not a substitute for -T.>
684 In other taint news, the C<exec LIST> and C<system LIST> have now been
685 considered too risky (think C<exec @ARGV>: it can start any program
686 with any arguments), and now the said forms cause a warning under
687 lexical warnings. You should carefully launder the arguments to
688 guarantee their validity. In future releases of Perl the forms will
689 become fatal errors so consider starting laundering now.
693 Tied hash interfaces are now required to have the EXISTS and DELETE
694 methods (either own or inherited).
698 If tr/// is just counting characters, it doesn't attempt to
703 untie() will now call an UNTIE() hook if it exists. See L<perltie>
708 L<utime> now supports C<utime undef, undef, @files> to change the
709 file timestamps to the current time.
713 The rules for allowing underscores (underbars) in numeric constants
714 have been relaxed and simplified: now you can have an underscore
715 simply B<between digits>.
719 Rather than relying on C's argv[0] (which may not contain a full pathname)
720 where possible $^X is now set by asking the operating system.
721 (eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD)
725 A new variable, C<${^TAINT}>, indicates whether taint mode is enabled.
729 You can now override the readline() builtin, and this overrides also
730 the <FILEHANDLE> angle bracket operator.
734 The command-line options -s and -F are now recognized on the shebang
739 Use of the C</c> match modifier without an accompanying C</g> modifier
740 elicits a new warning: C<Use of /c modifier is meaningless without /g>.
742 Use of C</c> in substitutions, even with C</g>, elicits
743 C<Use of /c modifier is meaningless in s///>.
745 Use of C</g> with C<split> elicits C<Use of /g modifier is meaningless
750 Support for the C<CLONE> special subroutine had been added.
751 With ithreads, when a new thread is created, all Perl data is cloned,
752 however non-Perl data cannot be cloned automatically. In C<CLONE> you
753 can do whatever you need to do, like for example handle the cloning of
754 non-Perl data, if necessary. C<CLONE> will be executed once for every
755 package that has it defined or inherited. It will be called in the
756 context of the new thread, so all modifications are made in the new area.
762 =head1 Modules and Pragmata
764 =head2 New Modules and Pragmata
770 C<Attribute::Handlers>, originally by Damian Conway and now maintained
771 by Arthur Bergman, allows a class to define attribute handlers.
774 use Attribute::Handlers;
775 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
777 # later, in some package using or inheriting from MyPack...
779 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
781 Both variables and routines can have attribute handlers. Handlers can
782 be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
783 exact compilation phase (BEGIN, CHECK, INIT, or END).
784 See L<Attribute::Handlers>.
788 C<B::Concise>, by Stephen McCamant, is a new compiler backend for
789 walking the Perl syntax tree, printing concise info about ops.
790 The output is highly customisable. See L<B::Concise>. [561+]
794 The new bignum, bigint, and bigrat pragmas, by Tels, implement
795 transparent bignum support (using the Math::BigInt, Math::BigFloat,
796 and Math::BigRat backends).
800 C<Class::ISA>, by Sean Burke, is a module for reporting the search
801 path for a class's ISA tree. See L<Class::ISA>.
805 C<Cwd> now has a split personality: if possible, an XS extension is
806 used, (this will hopefully be faster, more secure, and more robust)
807 but if not possible, the familiar Perl implementation is used.
811 C<Devel::PPPort>, originally by Kenneth Albanowski and now
812 maintained by Paul Marquess, has been added. It is primarily used
813 by C<h2xs> to enhance portability of XS modules between different
814 versions of Perl. See L<Devel::PPPort>.
818 C<Digest>, frontend module for calculating digests (checksums), from
819 Gisle Aas, has been added. See L<Digest>.
823 C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
824 RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
826 use Digest::MD5 'md5_hex';
828 $digest = md5_hex("Thirsty Camel");
830 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
832 NOTE: the C<MD5> backward compatibility module is deliberately not
833 included since its further use is discouraged.
835 See also L<PerlIO::via::QuotedPrint>.
839 C<Encode>, originally by Nick Ing-Simmons and now maintained by Dan
840 Kogai, provides a mechanism to translate between different character
841 encodings. Support for Unicode, ISO-8859-1, and ASCII are compiled in
842 to the module. Several other encodings (like the rest of the
843 ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese,
844 Japanese, and Korean encodings) are included and can be loaded at
845 runtime. (For space considerations, the largest Chinese encodings
846 have been separated into their own CPAN module, Encode::HanExtra,
847 which Encode will use if available). See L<Encode>.
849 Any encoding supported by Encode module is also available to the
850 ":encoding()" layer if PerlIO is used.
854 C<Hash::Util> is the interface to the new I<restricted hashes>
855 feature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and
856 Michael Schwern.) See L<Hash::Util>.
860 C<I18N::Langinfo> can be used to query locale information.
861 See L<I18N::Langinfo>.
865 C<I18N::LangTags>, by Sean Burke, has functions for dealing with
866 RFC3066-style language tags. See L<I18N::LangTags>.
870 C<ExtUtils::Constant>, by Nicholas Clark, is a new tool for extension
871 writers for generating XS code to import C header constants.
872 See L<ExtUtils::Constant>.
876 C<Filter::Simple>, by Damian Conway, is an easy-to-use frontend to
877 Filter::Util::Call. See L<Filter::Simple>.
883 use Filter::Simple sub {
884 while (my ($from, $to) = splice @_, 0, 2) {
893 use MyFilter qr/red/ => 'green';
895 print "red\n"; # this code is filtered, will print "green\n"
896 print "bored\n"; # this code is filtered, will print "bogreen\n"
900 print "red\n"; # this code is not filtered, will print "red\n"
904 C<File::Temp>, by Tim Jenness, allows one to create temporary files
905 and directories in an easy, portable, and secure way. See L<File::Temp>.
910 C<Filter::Util::Call>, by Paul Marquess, provides you with the
911 framework to write I<source filters> in Perl. For most uses, the
912 frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
916 C<if>, by Ilya Zakharevich, is a new pragma for conditional inclusion
921 L<libnet>, by Graham Barr, is a collection of perl5 modules related
922 to network programming. See L<Net::FTP>, L<Net::NNTP>, L<Net::Ping>
923 (not part of libnet, but related), L<Net::POP3>, L<Net::SMTP>,
926 Perl installation leaves libnet unconfigured; use F<libnetcfg>
931 C<List::Util>, by Graham Barr, is a selection of general-utility
932 list subroutines, such as sum(), min(), first(), and shuffle().
937 C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>
938 C<Locale::Language>, and L<Locale::Script>, by Neil Bowers, have
939 been added. They provide the codes for various locale standards, such
940 as "fr" for France, "usd" for US Dollar, and "ja" for Japanese.
944 $country = code2country('jp'); # $country gets 'Japan'
945 $code = country2code('Norway'); # $code gets 'no'
947 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
948 and L<Locale::Language>.
952 C<Locale::Maketext>, by Sean Burke, is a localization framework. See
953 L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
954 article about software localization, originally published in The Perl
955 Journal #13, and republished here with kind permission.
959 C<Math::BigRat> for big rational numbers, to accompany Math::BigInt and
960 Math::BigFloat, from Tels. See L<Math::BigRat>.
964 C<Memoize> can make your functions faster by trading space for time,
965 from Mark-Jason Dominus. See L<Memoize>.
969 C<MIME::Base64>, by Gisle Aas, allows you to encode data in base64,
970 as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
975 $encoded = encode_base64('Aladdin:open sesame');
976 $decoded = decode_base64($encoded);
978 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
984 C<MIME::QuotedPrint>, by Gisle Aas, allows you to encode data
985 in quoted-printable encoding, as defined in RFC 2045 - I<MIME
986 (Multipurpose Internet Mail Extensions)>.
988 use MIME::QuotedPrint;
990 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
991 $decoded = decode_qp($encoded);
993 print $encoded, "\n"; # "Smiley in Unicode: =263A"
995 See also L<PerlIO::via::QuotedPrint>.
999 C<NEXT>, by Damian Conway, is a pseudo-class for method redispatch.
1004 C<open> is a new pragma for setting the default I/O layers
1009 C<PerlIO::scalar>, by Nick Ing-Simmons, provides the implementation
1010 of IO to "in memory" Perl scalars as discussed above. It also serves
1011 as an example of a loadable PerlIO layer. Other future possibilities
1012 include PerlIO::Array and PerlIO::Code. See L<PerlIO::scalar>.
1016 C<PerlIO::via>, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
1017 PerlIO layer functionality provided by a class (typically implemented
1022 C<PerlIO::via::QuotedPrint>, by Elizabeth Mattijsen, is an example
1023 of a C<PerlIO::via> class:
1025 use PerlIO::via::QuotedPrint;
1026 open($fh,">:via(QuotedPrint)",$path);
1028 This will automatically convert everything output to C<$fh> to
1029 Quoted-Printable. See L<PerlIO::via> and L<PerlIO::via::QuotedPrint>.
1033 C<Pod::ParseLink>, by Russ Allbery, has been added,
1034 to parse LZ<><> links in pods as described in the new
1039 C<Pod::Text::Overstrike>, by Joe Smith, has been added.
1040 It converts POD data to formatted overstrike text.
1041 See L<Pod::Text::Overstrike>. [561+]
1045 C<Scalar::Util> is a selection of general-utility scalar subroutines,
1046 such as blessed(), reftype(), and tainted(). See L<Scalar::Util>.
1050 C<sort> is a new pragma for controlling the behaviour of sort().
1054 C<Storable> gives persistence to Perl data structures by allowing the
1055 storage and retrieval of Perl data to and from files in a fast and
1056 compact binary format. Because in effect Storable does serialisation
1057 of Perl data structures, with it you can also clone deep, hierarchical
1058 datastructures. Storable was originally created by Raphael Manfredi,
1059 but it is now maintained by Abhijit Menon-Sen. Storable has been
1060 enhanced to understand the two new hash features, Unicode keys and
1061 restricted hashes. See L<Storable>.
1065 C<Switch>, by Damian Conway, has been added. Just by saying
1069 you have C<switch> and C<case> available in Perl.
1075 case 1 { print "number 1" }
1076 case "a" { print "string a" }
1077 case [1..10,42] { print "number in list" }
1078 case (@array) { print "number in list" }
1079 case /\w+/ { print "pattern" }
1080 case qr/\w+/ { print "pattern" }
1081 case (%hash) { print "entry in hash" }
1082 case (\%hash) { print "entry in hash" }
1083 case (\&sub) { print "arg to subroutine" }
1084 else { print "previous case not true" }
1091 C<Test::More>, by Michael Schwern, is yet another framework for writing
1092 test scripts, more extensive than Test::Simple. See L<Test::More>.
1096 C<Test::Simple>, by Michael Schwern, has basic utilities for writing
1097 tests. See L<Test::Simple>.
1101 C<Text::Balanced>, by Damian Conway, has been added, for extracting
1102 delimited text sequences from strings.
1104 use Text::Balanced 'extract_delimited';
1106 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
1108 $a will be "'never say never'", $b will be ', he never said'.
1110 In addition to extract_delimited(), there are also extract_bracketed(),
1111 extract_quotelike(), extract_codeblock(), extract_variable(),
1112 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
1113 gen_extract_tagged(). With these, you can implement rather advanced
1114 parsing algorithms. See L<Text::Balanced>.
1118 C<threads>, by Arthur Bergman, is an interface to interpreter threads.
1119 Interpreter threads (ithreads) is the new thread model introduced in
1120 Perl 5.6 but only available as an internal interface for extension
1121 writers (and for Win32 Perl for C<fork()> emulation). See L<threads>,
1122 L<threads::shared>, and L<perlthrtut>.
1126 C<threads::shared>, by Arthur Bergman, allows data sharing for
1127 interpreter threads. In the ithreads model any data sharing between
1128 threads must be explicit, as opposed to the old 5.005 thread model
1129 where data sharing was implicit. See L<threads::shared>.
1133 C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
1134 lines of a file. See L<Tie::File>.
1138 C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
1139 See L<Tie::Memoize>.
1143 C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
1144 references (unlike the standard Tie::RefHash) The module is contained
1145 within Tie::RefHash. See L<Tie::RefHash>.
1149 C<Time::HiRes>, by Douglas E. Wegscheid, provides high resolution
1150 timing (ualarm, usleep, and gettimeofday). See L<Time::HiRes>.
1154 C<Unicode::UCD> offers a querying interface to the Unicode Character
1155 Database. See L<Unicode::UCD>.
1159 C<Unicode::Collate>, by SADAHIRO Tomoyuki, implements the UCA
1160 (Unicode Collation Algorithm) for sorting Unicode strings.
1161 See L<Unicode::Collate>.
1165 C<Unicode::Normalize>, by SADAHIRO Tomoyuki, implements the various
1166 Unicode normalization forms. See L<Unicode::Normalize>.
1170 C<XS::APItest>, by Tim Jenness, is a test extension that exercises XS
1171 APIs. Currently only C<printf()> is tested: how to output various
1172 basic data types from XS.
1176 C<XS::Typemap>, by Tim Jenness, is a test extension that exercises
1177 XS typemaps. Nothing gets installed, but the code is worth studying
1178 for extension writers.
1182 =head2 Updated And Improved Modules and Pragmata
1188 The following independently supported modules have been updated to the
1189 newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
1190 Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
1191 (Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser, Storable,
1192 Term::ANSIColor, Test, Text-Tabs+Wrap.
1196 attributes::reftype() now works on tied arguments.
1200 AutoLoader can now be disabled with C<no AutoLoader;>.
1204 B::Deparse has been significantly enhanced by Robin Houston. It can
1205 now deparse almost all of the standard test suite (so that the tests
1206 still succeed). There is a make target "test.deparse" for trying this
1211 Carp now has better interface documentation, and the @CARP_NOT
1212 interface has been added to get optional control over where errors
1213 are reported independently of @ISA, by Ben Tilly.
1217 Class::Struct can now define the classes in compile time.
1221 Class::Struct now assigns the array/hash element if the accessor
1222 is called with an array/hash element as the B<sole> argument.
1226 The return value of Cwd::fastcwd() is now tainted.
1230 Data::Dumper now has an option to sort hashes.
1234 Data::Dumper now has an option to dump code references
1239 DB_File now supports newer Berkeley DB versions, among
1244 Devel::Peek now has an interface for the Perl memory statistics
1245 (this works only if you are using perl's malloc, and if you have
1246 compiled with debugging).
1250 The English module can now be used without the infamous performance
1253 use English '-no_match_vars';
1255 (Assuming, of course, that you don't need the troublesome variables
1256 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1257 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1261 ExtUtils::MakeMaker has been significantly cleaned up and fixed.
1262 The enhanced version has also been backported to earlier releases
1263 of Perl and submitted to CPAN so that the earlier releases can
1268 The arguments of WriteMakefile() in Makefile.PL are now checked
1269 for sanity much more carefully than before. This may cause new
1270 warnings when modules are being installed. See L<ExtUtils::MakeMaker>
1275 ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1276 leads to better portability.
1280 Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clark
1281 to use the new-style constant dispatch section (see L<ExtUtils::Constant>).
1282 This means that they will be more robust and hopefully faster.
1286 File::Find now chdir()s correctly when chasing symbolic links. [561]
1290 File::Find now has pre- and post-processing callbacks. It also
1291 correctly changes directories when chasing symbolic links. Callbacks
1292 (naughtily) exiting with "next;" instead of "return;" now work.
1296 File::Find is now (again) reentrant. It also has been made
1301 The warnings issued by File::Find now belong to their own category.
1302 You can enable/disable them with C<use/no warnings 'File::Find';>.
1306 File::Glob::glob() has been renamed to File::Glob::bsd_glob()
1307 because the name clashes with the builtin glob(). The older
1308 name is still available for compatibility, but is deprecated. [561]
1312 File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1313 the returned list of filenames.
1317 IPC::Open3 now allows the use of numeric file descriptors.
1321 IO::Socket now has an atmark() method, which returns true if the socket
1322 is positioned at the out-of-band mark. The method is also exportable
1323 as a sockatmark() function.
1327 IO::Socket::INET failed to open the specified port if the service name
1328 was not known. It now correctly uses the supplied port number as is. [561]
1332 IO::Socket::INET has support for the ReusePort option (if your
1333 platform supports it). The Reuse option now has an alias, ReuseAddr.
1334 For clarity, you may want to prefer ReuseAddr.
1338 IO::Socket::INET now supports a value of zero for C<LocalPort>
1339 (usually meaning that the operating system will make one up.)
1343 'use lib' now works identically to @INC. Removing directories
1344 with 'no lib' now works.
1348 Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels.
1349 They are now magnitudes faster, and they support various bignum
1350 libraries such as GMP and PARI as their backends.
1354 Math::Complex handles inf, NaN etc., better.
1358 Net::Ping has been considerably enhanced by Rob Brown: multihoming is
1359 now supported, Win32 functionality is better, there is now time
1360 measuring functionality (optionally high-resolution using
1361 Time::HiRes), and there is now "external" protocol which uses
1362 Net::Ping::External module which runs your external ping utility and
1363 parses the output. A version of Net::Ping::External is available in
1366 Note that some of the Net::Ping tests are disabled when running
1367 under the Perl distribution since one cannot assume one or more
1368 of the following: enabled echo port at localhost, full Internet
1369 connectivity, or sympathetic firewalls. You can set the environment
1370 variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test
1371 suite to enable all the Net::Ping tests.
1375 POSIX::sigaction() is now much more flexible and robust.
1376 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1377 handlers, installing new handlers was not atomic.
1381 In Safe, C<%INC> is now localised in a Safe compartment so that
1386 In SDBM_File on dosish platforms, some keys went missing because of
1387 lack of support for files with "holes". A workaround for the problem
1392 In Search::Dict one can now have a pre-processing hook for the
1393 lines being searched.
1397 The Shell module now has an OO interface.
1401 In Sys::Syslog there is now a failover mechanism that will go
1402 through alternative connection mechanisms until the message
1403 is successfully logged.
1407 The Test module has been significantly enhanced.
1411 Time::Local::timelocal() does not handle fractional seconds anymore.
1412 The rationale is that neither does localtime(), and timelocal() and
1413 localtime() are supposed to be inverses of each other.
1417 The vars pragma now supports declaring fully qualified variables.
1418 (Something that C<our()> does not and will not support.)
1422 The C<utf8::> name space (as in the pragma) provides various
1423 Perl-callable functions to provide low level access to Perl's
1424 internal Unicode representation. At the moment only length()
1425 has been implemented.
1429 =head1 Utility Changes
1435 Emacs perl mode (emacs/cperl-mode.el) has been updated to version
1440 F<emacs/e2ctags.pl> is now much faster.
1444 C<enc2xs> is a tool for people adding their own encodings to the
1449 C<h2ph> now supports C trigraphs.
1453 C<h2xs> now produces a template README.
1457 C<h2xs> now uses C<Devel::PPPort> for better portability between
1458 different versions of Perl.
1462 C<h2xs> uses the new L<ExtUtils::Constant|ExtUtils::Constant> module
1463 which will affect newly created extensions that define constants.
1464 Since the new code is more correct (if you have two constants where the
1465 first one is a prefix of the second one, the first constant B<never>
1466 got defined), less lossy (it uses integers for integer constant,
1467 as opposed to the old code that used floating point numbers even for
1468 integer constants), and slightly faster, you might want to consider
1469 regenerating your extension code (the new scheme makes regenerating
1470 easy). L<h2xs> now also supports C trigraphs.
1474 C<libnetcfg> has been added to configure libnet.
1478 C<perlbug> is now much more robust. It also sends the bug report to
1479 perl.org, not perl.com.
1483 C<perlcc> has been rewritten and its user interface (that is,
1484 command line) is much more like that of the UNIX C compiler, cc.
1485 (The perlbc tools has been removed. Use C<perlcc -B> instead.)
1486 B<Note that perlcc is still considered very experimental and
1491 C<perlivp> is a new Installation Verification Procedure utility
1492 for running any time after installing Perl.
1496 C<piconv> is an implementation of the character conversion utility
1497 C<iconv>, demonstrating the new Encode module.
1501 C<pod2html> now allows specifying a cache directory.
1505 C<pod2html> now produces XHTML 1.0.
1509 C<pod2html> now understands POD written using different line endings
1510 (PC-like CRLF versus UNIX-like LF versus MacClassic-like CR).
1514 C<s2p> has been completely rewritten in Perl. (It is in fact a full
1515 implementation of sed in Perl: you can use the sed functionality by
1516 using the C<psed> utility.)
1520 C<xsubpp> now understands POD documentation embedded in the *.xs
1525 C<xsubpp> now supports the OUT keyword.
1529 =head1 New Documentation
1535 perl56delta details the changes between the 5.005 release and the
1540 perlclib documents the internal replacements for standard C library
1541 functions. (Interesting only for extension writers and Perl core
1546 perldebtut is a Perl debugging tutorial. [561+]
1550 perlebcdic contains considerations for running Perl on EBCDIC
1555 perlintro is a gentle introduction to Perl.
1559 perliol documents the internals of PerlIO with layers.
1563 perlmodstyle is a style guide for writing modules.
1567 perlnewmod tells about writing and submitting a new module. [561+]
1571 perlpacktut is a pack() tutorial.
1575 perlpod has been rewritten to be clearer and to record the best
1576 practices gathered over the years.
1580 perlpodspec is a more formal specification of the pod format,
1581 mainly of interest for writers of pod applications, not to
1582 people writing in pod.
1586 perlretut is a regular expression tutorial. [561+]
1590 perlrequick is a regular expressions quick-start guide.
1591 Yes, much quicker than perlretut. [561]
1595 perltodo has been updated.
1599 perltootc has been renamed as perltooc (to not to conflict
1600 with perltoot in filesystems restricted to "8.3" names).
1604 perluniintro is an introduction to using Unicode in Perl.
1605 (perlunicode is more of a detailed reference and background
1610 perlutil explains the command line utilities packaged with the Perl
1611 distribution. [561+]
1615 The following platform-specific documents are available before
1616 the installation as README.I<platform>, and after the installation
1619 perlaix perlamiga perlapollo perlbeos perlbs2000
1620 perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux
1621 perlhurd perlirix perlmachten perlmacos perlmint perlmpeix
1622 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1623 perltru64 perluts perlvmesa perlvms perlvos perlwin32
1625 These documents usually detail one or more of the following subjects:
1626 configuring, building, testing, installing, and sometimes also using
1627 Perl on the said platform.
1629 Eastern Asian Perl users are now welcomed in their own languages:
1630 README.jp (Japanese), README.ko (Korean), README.cn (simplified
1631 Chinese) and README.tw (traditional Chinese), which are written in
1632 normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These
1633 will get installed as
1635 perljp perlko perlcn perltw
1641 The documentation for the POSIX-BC platform is called "BS2000", to avoid
1642 confusion with the Perl POSIX module.
1646 The documentation for the WinCE platform is called perlce (README.ce
1647 in the source code kit), to avoid confusion with the perlwin32
1648 documentation on 8.3-restricted filesystems.
1652 =head1 Performance Enhancements
1658 map() could get pathologically slow when the result list it generates
1659 is larger than the source list. The performance has been improved for
1660 common scenarios. [561]
1664 sort() is also fully reentrant, in the sense that the sort function
1665 can itself call sort(). This did not work reliably in previous
1670 sort() has been changed to use primarily mergesort internally as
1671 opposed to the earlier quicksort. For very small lists this may
1672 result in slightly slower sorting times, but in general the speedup
1673 should be at least 20%. Additional bonuses are that the worst case
1674 behaviour of sort() is now better (in computer science terms it now
1675 runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1676 worst-case run time behaviour), and that sort() is now stable
1677 (meaning that elements with identical keys will stay ordered as they
1678 were before the sort). See the C<sort> pragma for information.
1680 The story in more detail: suppose you want to serve yourself a little
1683 @digits = ( 3,1,4,1,5,9 );
1685 A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1686 Which C<1> comes first is hard to know, since one C<1> looks pretty
1687 much like any other. You can regard this as totally trivial,
1688 or somewhat profound. However, if you just want to sort the even
1689 digits ahead of the odd ones, then what will
1691 sort { ($a % 2) <=> ($b % 2) } @digits;
1693 yield? The only even digit, C<4>, will come first. But how about
1694 the odd numbers, which all compare equal? With the quicksort algorithm
1695 used to implement Perl 5.6 and earlier, the order of ties is left up
1696 to the sort. So, as you add more and more digits of Pi, the order
1697 in which the sorted even and odd digits appear will change.
1698 and, for sufficiently large slices of Pi, the quicksort algorithm
1699 in Perl 5.8 won't return the same results even if reinvoked with the
1700 same input. The justification for this rests with quicksort's
1701 worst case behavior. If you run
1703 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1705 (something you might approximate if you wanted to merge two sorted
1706 arrays using sort), doubling $N doesn't just double the quicksort time,
1707 it I<quadruples> it. Quicksort has a worst case run time that can
1708 grow like N**2, so-called I<quadratic> behaviour, and it can happen
1709 on patterns that may well arise in normal use. You won't notice this
1710 for small arrays, but you I<will> notice it with larger arrays,
1711 and you may not live long enough for the sort to complete on arrays
1712 of a million elements. So the 5.8 quicksort scrambles large arrays
1713 before sorting them, as a statistical defence against quadratic behaviour.
1714 But that means if you sort the same large array twice, ties may be
1715 broken in different ways.
1717 Because of the unpredictability of tie-breaking order, and the quadratic
1718 worst-case behaviour, quicksort was I<almost> replaced completely with
1719 a stable mergesort. I<Stable> means that ties are broken to preserve
1720 the original order of appearance in the input array. So
1722 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1724 will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1725 appear in the output in the same order they appeared in the input.
1726 Mergesort has worst case O(N log N) behaviour, the best value
1727 attainable. And, ironically, this mergesort does particularly
1728 well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1729 in O(N) time. But quicksort was rescued at the last moment because
1730 it is faster than mergesort on certain inputs and platforms.
1731 For example, if you really I<don't> care about the order of even
1732 and odd digits, quicksort will run in O(N) time; it's very good
1733 at sorting many repetitions of a small number of distinct elements.
1734 The quicksort divide and conquer strategy works well on platforms
1735 with relatively small, very fast, caches. Eventually, the problem gets
1736 whittled down to one that fits in the cache, from which point it
1737 benefits from the increased memory speed.
1739 Quicksort was rescued by implementing a sort pragma to control aspects
1740 of the sort. The B<stable> subpragma forces stable behaviour,
1741 regardless of algorithm. The B<_quicksort> and B<_mergesort>
1742 subpragmas are heavy-handed ways to select the underlying implementation.
1743 The leading C<_> is a reminder that these subpragmas may not survive
1744 beyond 5.8. More appropriate mechanisms for selecting the implementation
1745 exist, but they wouldn't have arrived in time to save quicksort.
1749 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1750 ( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is
1751 reasonably fast while producing a much better spread of values than
1752 the old hashing algorithm (originally by Chris Torek, later tweaked by
1753 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1754 all 3-char printable ASCII keys comes much closer to passing the
1755 DIEHARD random number generation tests. According to perlbench, this
1756 change has not affected the overall speed of Perl.
1760 unshift() should now be noticeably faster.
1764 =head1 Installation and Configuration Improvements
1766 =head2 Generic Improvements
1772 INSTALL now explains how you can configure Perl to use 64-bit
1773 integers even on non-64-bit platforms.
1777 Policy.sh policy change: if you are reusing a Policy.sh file
1778 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1779 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1780 them will now be changed to the new prefix, /foo/bar. (Previously
1781 only $prefix changed.) If you do not like this new behaviour,
1782 specify prefix, siteprefix, and vendorprefix explicitly.
1786 A new optional location for Perl libraries, otherlibdirs, is available.
1787 It can be used for example for vendor add-ons without disturbing Perl's
1788 own library directories.
1792 In many platforms, the vendor-supplied 'cc' is too stripped-down to
1793 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1794 to be the case and 'cc' does not seem to be the GNU C compiler
1795 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1799 gcc needs to closely track the operating system release to avoid
1800 build problems. If Configure finds that gcc was built for a different
1801 operating system release than is running, it now gives a clearly visible
1802 warning that there may be trouble ahead.
1806 Since Perl 5.8 is not binary-compatible with previous releases
1807 of Perl, Configure no longer suggests including the 5.005
1812 Configure C<-S> can now run non-interactively. [561]
1816 Configure support for pdp11-style memory models has been removed due
1817 to obsolescence. [561]
1821 configure.gnu now works with options with whitespace in them.
1825 installperl now outputs everything to STDERR.
1829 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1830 get appended to the $Config{archname} (also known as $^O) anymore.
1831 Instead, if you explicitly choose not to use perlio (Configure command
1832 line option -Uuseperlio), you will get "-stdio" appended.
1836 Another change related to the architecture name is that "-64all"
1837 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1838 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1842 In AFS installations, one can configure the root of the AFS to be
1843 somewhere else than the default F</afs> by using the Configure
1844 parameter C<-Dafsroot=/some/where/else>.
1848 APPLLIB_EXP, a lesser-known configuration-time definition, has been
1849 documented. It can be used to prepend site-specific directories
1850 to Perl's default search path (@INC); see INSTALL for information.
1854 The version of Berkeley DB used when the Perl (and, presumably, the
1855 DB_File extension) was built is now available as
1856 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1857 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1858 DB_VERSION_PATCH_CFG> from C.
1862 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1863 has been documented in INSTALL.
1867 If you have CPAN access (either network or a local copy such as a
1868 CD-ROM) you can during specify extra modules to Configure to build and
1869 install with Perl using the -Dextras=... option. See INSTALL for
1874 In addition to config.over, a new override file, config.arch, is
1875 available. This file is supposed to be used by hints file writers
1876 for architecture-wide changes (as opposed to config.over which is
1877 for site-wide changes).
1881 If your file system supports symbolic links, you can build Perl outside
1882 of the source directory by
1884 mkdir /tmp/perl/build/directory
1885 cd /tmp/perl/build/directory
1886 sh /path/to/perl/source/Configure -Dmksymlinks ...
1888 This will create in /tmp/perl/build/directory a tree of symbolic links
1889 pointing to files in /path/to/perl/source. The original files are left
1890 unaffected. After Configure has finished, you can just say
1894 and Perl will be built and tested, all in /tmp/perl/build/directory.
1899 For Perl developers, several new make targets for profiling
1900 and debugging have been added; see L<perlhack>.
1906 Use of the F<gprof> tool to profile Perl has been documented in
1907 L<perlhack>. There is a make target called "perl.gprof" for
1908 generating a gprofiled Perl executable.
1912 If you have GCC 3, there is a make target called "perl.gcov" for
1913 creating a gcoved Perl executable for coverage analysis. See
1918 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1919 have been added; see L<perlhack> for more information about pixie and
1926 Guidelines of how to construct minimal Perl installations have
1927 been added to INSTALL.
1931 The Thread extension is now not built at all under ithreads
1932 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1933 Thread extension requires being Configured with C<-Duse5005threads>).
1935 B<Note that the 5.005 threads are unsupported and deprecated: if you
1936 have code written for the old threads you should migrate it to the
1937 new ithreads model.>
1941 The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
1942 floating-point numbers is now more picky about using sprintf %.*g
1943 rules for the conversion. Some platforms that used to use gcvt may
1944 now resort to the slower sprintf.
1948 The obsolete method of making a special (e.g., debugging) flavor
1951 make LIBPERL=libperld.a
1953 has been removed. Use -DDEBUGGING instead.
1957 =head2 New Or Improved Platforms
1959 For the list of platforms known to support Perl,
1960 see L<perlport/"Supported Platforms">.
1966 AIX dynamic loading should be now better supported.
1970 AIX should now work better with gcc, threads, and 64-bitness. Also the
1971 long doubles support in AIX should be better now. See L<perlaix>.
1975 AtheOS ( http://www.atheos.cx/ ) is a new platform.
1979 BeOS has been reclaimed.
1983 The DG/UX platform now supports 5.005-style threads.
1988 The DYNIX/ptx platform (also known as dynixptx) is supported at or
1993 EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA)
1994 have been regained. Many test suite tests still fail and the
1995 co-existence of Unicode and EBCDIC isn't quite settled, but the
1996 situation is much better than with Perl 5.6. See L<perlos390>,
1997 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
2001 Building perl with -Duseithreads or -Duse5005threads now works under
2002 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
2003 need a thread library package installed. See README.hpux. [561]
2007 Mac OS Classic is now supported in the mainstream source package
2008 (MacPerl has of course been available since perl 5.004 but now the
2009 source code bases of standard Perl and MacPerl have been synchronised)
2014 Mac OS X (or Darwin) should now be able to build Perl even on HFS+
2015 filesystems. (The case-insensitivity used to confuse the Perl build
2020 NCR MP-RAS is now supported. [561]
2024 All the NetBSD specific patches (except for the installation
2025 specific ones) have been merged back to the main distribution.
2029 NetWare from Novell is now supported. See L<perlnetware>.
2033 NonStop-UX is now supported. [561]
2037 NEC SUPER-UX is now supported.
2041 All the OpenBSD specific patches (except for the installation
2042 specific ones) have been merged back to the main distribution.
2046 Perl has been tested with the GNU pth userlevel thread package
2047 ( http://www.gnu.org/software/pth/pth.html ). All thread tests
2048 of Perl now work, but not without adding some yield()s to the tests,
2049 so while pth (and other userlevel thread implementations) can be
2050 considered to be "working" with Perl ithreads, keep in mind the
2051 possible non-preemptability of the underlying thread implementation.
2055 Stratus VOS is now supported using Perl's native build method
2056 (Configure). This is the recommended method to build Perl on
2057 VOS. The older methods, which build miniperl, are still
2058 available. See L<perlvos>. [561+]
2062 The Amdahl UTS UNIX mainframe platform is now supported. [561]
2066 WinCE is now supported. See L<perlce>.
2070 z/OS (formerly known as OS/390, formerly known as MVS OE) now has
2071 support for dynamic loading. This is not selected by default,
2072 however, you must specify -Dusedl in the arguments of Configure. [561]
2076 =head1 Selected Bug Fixes
2078 Numerous memory leaks and uninitialized memory accesses have been
2079 hunted down. Most importantly, anonymous subs used to leak quite
2086 The autouse pragma didn't work for Multi::Part::Function::Names.
2090 caller() could cause core dumps in certain situations. Carp was
2091 sometimes affected by this problem. In particular, caller() now
2092 returns a subroutine name of C<(unknown)> for subroutines that have
2093 been removed from the symbol table.
2097 chop(@list) in list context returned the characters chopped in
2098 reverse order. This has been reversed to be in the right order. [561]
2102 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
2103 when building the Perl binary. The only exception to this is SunOS 4.x,
2104 which needs them. [561]
2108 The behaviour of non-decimal but numeric string constants such as
2109 "0x23" was platform-dependent: in some platforms that was seen as 35,
2110 in some as 0, in some as a floating point number (don't ask). This
2111 was caused by Perl's using the operating system libraries in a situation
2112 where the result of the string to number conversion is undefined: now
2113 Perl consistently handles such strings as zero in numeric contexts.
2117 Several debugger fixes: exit code now reflects the script exit code,
2118 condition C<"0"> now treated correctly, the C<d> command now checks
2119 line number, C<$.> no longer gets corrupted, and all debugger output
2120 now goes correctly to the socket if RemotePort is set. [561]
2124 The debugger (perl5db.pl) has been modified to present a more
2125 consistent commands interface, via (CommandSet=580). perl5db.t was
2126 also added to test the changes, and as a placeholder for further tests.
2132 The debugger has a new C<dumpDepth> option to control the maximum
2133 depth to which nested structures are dumped. The C<x> command has
2134 been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a
2135 depth of at most I<N> levels.
2139 The debugger can now show lexical variables if you have the CPAN
2140 module PadWalker installed.
2144 The order of DESTROYs has been made more predictable.
2148 Perl 5.6.0 could emit spurious warnings about redefinition of
2149 dl_error() when statically building extensions into perl.
2150 This has been corrected. [561]
2154 L<dprofpp> -R didn't work.
2158 C<*foo{FORMAT}> now works.
2162 Infinity is now recognized as a number.
2166 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
2167 the Tk extension with 5.6.0.) [561]
2171 Lexicals I: lexicals outside an eval "" weren't resolved
2172 correctly inside a subroutine definition inside the eval "" if they
2173 were not already referenced in the top level of the eval""ed code.
2177 Lexicals II: lexicals leaked at file scope into subroutines that
2178 were declared before the lexicals.
2182 Lexical warnings now propagating correctly between scopes
2183 and into C<eval "...">.
2187 C<use warnings qw(FATAL all)> did not work as intended. This has been
2192 warnings::enabled() now reports the state of $^W correctly if the caller
2193 isn't using lexical warnings. [561]
2197 Line renumbering with eval and C<#line> now works. [561]
2201 Fixed numerous memory leaks, especially in eval "".
2205 Localised tied variables no longer leak memory
2208 tie my %tied_hash => 'Tie::StdHash';
2212 # Used to leak memory every time local() was called;
2213 # in a loop, this added up.
2214 local($tied_hash{Foo}) = 1;
2218 Localised hash elements (and %ENV) are correctly unlocalised to not
2219 exist, if they didn't before they were localised.
2223 tie my %tied_hash => 'Tie::StdHash';
2227 # Nothing has set the FOO element so far
2229 { local $tied_hash{FOO} = 'Bar' }
2231 # This used to print, but not now.
2232 print "exists!\n" if exists $tied_hash{FOO};
2234 As a side effect of this fix, tied hash interfaces B<must> define
2235 the EXISTS and DELETE methods.
2239 mkdir() now ignores trailing slashes in the directory name,
2240 as mandated by POSIX.
2244 Some versions of glibc have a broken modfl(). This affects builds
2245 with C<-Duselongdouble>. This version of Perl detects this brokenness
2246 and has a workaround for it. The glibc release 2.2.2 is known to have
2247 fixed the modfl() bug.
2251 Modulus of unsigned numbers now works (4063328477 % 65535 used to
2252 return 27406, instead of 27047). [561]
2256 Some "not a number" warnings introduced in 5.6.0 eliminated to be
2257 more compatible with 5.005. Infinity is now recognised as a number. [561]
2261 Numeric conversions did not recognize changes in the string value
2262 properly in certain circumstances. [561]
2266 Attributes (such as :shared) didn't work with our().
2270 our() variables will not cause bogus "Variable will not stay shared"
2275 "our" variables of the same name declared in two sibling blocks
2276 resulted in bogus warnings about "redeclaration" of the variables.
2277 The problem has been corrected. [561]
2281 pack "Z" now correctly terminates the string with "\0".
2285 Fix password routines which in some shadow password platforms
2286 (e.g. HP-UX) caused getpwent() to return every other entry.
2290 The PERL5OPT environment variable (for passing command line arguments
2291 to Perl) didn't work for more than a single group of options. [561]
2295 PERL5OPT with embedded spaces didn't work.
2299 printf() no longer resets the numeric locale to "C".
2303 C<qw(a\\b)> now parses correctly as C<'a\\b'>: that is, as three
2304 characters, not four. [561]
2308 pos() did not return the correct value within s///ge in earlier
2309 versions. This is now handled correctly. [561]
2313 Printing quads (64-bit integers) with printf/sprintf now works
2314 without the q L ll prefixes (assuming you are on a quad-capable platform).
2318 Regular expressions on references and overloaded scalars now work. [561+]
2322 Right-hand side magic (GMAGIC) could in many cases such as string
2323 concatenation be invoked too many times.
2327 scalar() now forces scalar context even when used in void context.
2331 SOCKS support is now much more robust.
2335 sort() arguments are now compiled in the right wantarray context
2336 (they were accidentally using the context of the sort() itself).
2337 The comparison block is now run in scalar context, and the arguments
2338 to be sorted are always provided list context. [561]
2342 Changed the POSIX character class C<[[:space:]]> to include the (very
2343 rarely used) vertical tab character. Added a new POSIX-ish character
2344 class C<[[:blank:]]> which stands for horizontal whitespace
2345 (currently, the space and the tab).
2349 The tainting behaviour of sprintf() has been rationalized. It does
2350 not taint the result of floating point formats anymore, making the
2351 behaviour consistent with that of string interpolation. [561]
2355 Some cases of inconsistent taint propagation (such as within hash
2356 values) have been fixed.
2360 The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
2361 of simple pattern matches. These are now handled better. [561]
2365 Regular expression debug output (whether through C<use re 'debug'>
2366 or via C<-Dr>) now looks better. [561]
2370 Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
2371 bug has been fixed. [561]
2375 Use of $& could trigger a core dump under some situations. This
2376 is now avoided. [561]
2380 The regular expression captured submatches ($1, $2, ...) are now
2381 more consistently unset if the match fails, instead of leaving false
2382 data lying around in them. [561]
2386 readline() on files opened in "slurp" mode could return an extra
2387 "" (blank line) at the end in certain situations. This has been
2392 Autovivification of symbolic references of special variables described
2393 in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
2398 Sys::Syslog ignored the C<LOG_AUTH> constant.
2402 $AUTOLOAD, sort(), lock(), and spawning subprocesses
2403 in multiple threads simultaneously are now thread-safe.
2407 Tie::Array's SPLICE method was broken.
2411 Allow a read-only string on the left-hand side of a non-modifying tr///.
2415 If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
2416 correctly pass to it.
2420 Several Unicode fixes.
2426 BOMs (byte order marks) at the beginning of Perl files
2427 (scripts, modules) should now be transparently skipped.
2428 UTF-16 and UCS-2 encoded Perl files should now be read correctly.
2432 The character tables have been updated to Unicode 3.2.0.
2436 Comparing with utf8 data does not magically upgrade non-utf8 data
2437 into utf8. (This was a problem for example if you were mixing data
2438 from I/O and Unicode data: your output might have got magically encoded
2443 Generating illegal Unicode code points such as U+FFFE, or the UTF-16
2444 surrogates, now also generates an optional warning.
2448 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
2452 Concatenation with the C<.> operator or via variable interpolation,
2453 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2454 substitution with C<s///>, single-quoted UTF8, should now work.
2458 The C<tr///> operator now works. Note that the C<tr///CU>
2459 functionality has been removed (but see pack('U0', ...)).
2463 C<eval "v200"> now works.
2467 Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2468 This has been corrected. [561]
2472 Zero entries were missing from the Unicode classes such as C<IsDigit>.
2478 Large unsigned numbers (those above 2**31) could sometimes lose their
2479 unsignedness, causing bogus results in arithmetic operations. [561]
2483 The Perl parser has been stress tested using both random input and
2484 Markov chain input and the few found crashes and lockups have been
2489 =head2 Platform Specific Changes and Fixes
2497 Perl now works on post-4.0 BSD/OSes.
2503 Setting C<$0> now works (as much as possible; see L<perlvar> for details).
2509 Numerous updates; currently synchronised with Cygwin 1.3.10.
2513 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2519 EPOC now better supported. See README.epoc. [561]
2525 Perl now works on post-3.0 FreeBSDs.
2531 README.hpux updated; C<Configure -Duse64bitall> now works;
2532 now uses HP-UX malloc instead of Perl malloc.
2538 Numerous compilation flag and hint enhancements; accidental mixing
2539 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
2549 Long doubles should now work (see INSTALL). [561]
2553 Linux previously had problems related to sockaddrlen when using
2554 accept(), recvfrom() (in Perl: recv()), getpeername(), and
2563 Compilation of the standard Perl distribution in Mac OS Classic should
2564 now work if you have the Metrowerks development environment and the
2565 missing Mac-specific toolkit bits. Contact the macperl mailing list
2572 MPE/iX update after Perl 5.6.0. See README.mpeix. [561]
2576 NetBSD/threads: try installing the GNU pth (should be in the
2577 packages collection, or http://www.gnu.org/software/pth/),
2578 and Configure with -Duseithreads.
2584 Perl now works on NetBSD/sparc.
2590 Now works with usethreads (see INSTALL). [561]
2596 64-bitness using the Sun Workshop compiler now works.
2602 The native build method requires at least VOS Release 14.5.0
2603 and GNU C++/GNU Tools 2.0.1 or later. The Perl pack function
2604 now maps overflowed values to +infinity and underflowed values
2609 Tru64 (aka Digital UNIX, aka DEC OSF/1)
2611 The operating system version letter now recorded in $Config{osvers}.
2612 Allow compiling with gcc (previously explicitly forbidden). Compiling
2613 with gcc still not recommended because buggy code results, even with
2620 Fixed various alignment problems that lead into core dumps either
2621 during build or later; no longer dies on math errors at runtime;
2622 now using full quad integers (64 bits), previously was using
2623 only 46 bit integers for speed.
2629 See L</"Socket Extension Dynamic in VMS"> and L</"IEEE-format Floating Point
2630 Default on OpenVMS Alpha"> for important changes not otherwise listed here.
2632 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2633 (see INSTALL); now works with Perl's malloc.
2635 The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2636 unimplemented. It now works as documented.
2638 The C<waitpid> emulation has been improved. The worst bug (now fixed)
2639 was that a pid of -1 would cause a wildcard search of all processes on
2642 POSIX-style signals are now emulated much better on VMS versions prior
2645 The C<system> function and backticks operator have improved
2646 functionality and better error handling. [561]
2648 File access tests now use current process privileges rather than the
2649 user's default privileges, which could sometimes result in a mismatch
2650 between reported access and actual access. This improvement is only
2651 available on VMS v6.0 and later.
2653 There is a new C<kill> implementation based on C<sys$sigprc> that allows
2654 older VMS systems (pre-7.0) to use C<kill> to send signals rather than
2655 simply force exit. This implementation also allows later systems to
2656 call C<kill> from within a signal handler.
2658 Iterative logical name translations are now limited to 10 iterations in
2659 imitation of SHOW LOGICAL and other OpenVMS facilities.
2669 Signal handling now works better than it used to. It is now implemented
2670 using a Windows message loop, and is therefore less prone to random
2675 fork() emulation is now more robust, but still continues to have a few
2676 esoteric bugs and caveats. See L<perlfork> for details. [561+]
2680 A failed (pseudo)fork now returns undef and sets errno to EAGAIN. [561]
2684 The following modules now work on Windows:
2686 ExtUtils::Embed [561]
2693 IO::File::new_tmpfile() is no longer limited to 32767 invocations
2698 Better chdir() return value for a non-existent directory.
2702 Compiling perl using the 64-bit Platform SDK tools is now supported.
2706 The Win32::SetChildShowWindow() builtin can be used to control the
2707 visibility of windows created by child processes. See L<Win32> for
2712 Non-blocking waits for child processes (or pseudo-processes) are
2713 supported via C<waitpid($pid, &POSIX::WNOHANG)>.
2717 The behavior of system() with multiple arguments has been rationalized.
2718 Each unquoted argument will be automatically quoted to protect whitespace,
2719 and any existing whitespace in the arguments will be preserved. This
2720 improves the portability of system(@args) by avoiding the need for
2721 Windows C<cmd> shell specific quoting in perl programs.
2723 Note that this means that some scripts that may have relied on earlier
2724 buggy behavior may no longer work correctly. For example,
2725 C<system("nmake /nologo", @args)> will now attempt to run the file
2726 C<nmake /nologo> and will fail when such a file isn't found.
2727 On the other hand, perl will now execute code such as
2728 C<system("c:/Program Files/MyApp/foo.exe", @args)> correctly.
2732 The perl header files no longer suppress common warnings from the
2733 Microsoft Visual C++ compiler. This means that additional warnings may
2734 now show up when compiling XS code.
2738 Borland C++ v5.5 is now a supported compiler that can build Perl.
2739 However, the generated binaries continue to be incompatible with those
2740 generated by the other supported compilers (GCC and Visual C++). [561]
2744 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2749 Current directory entries in %ENV are now correctly propagated to child
2754 New %ENV entries now propagate to subprocesses. [561]
2758 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2759 Other bugs in chdir() and Cwd::cwd() have also been fixed. [561]
2763 The makefiles now default to the features enabled in ActiveState ActivePerl
2764 (a popular Win32 binary distribution). [561]
2768 HTML files will now be installed in c:\perl\html instead of
2769 c:\perl\lib\pod\html
2773 REG_EXPAND_SZ keys are now allowed in registry settings used by perl. [561]
2777 Can now send() from all threads, not just the first one. [561]
2781 ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries. [561]
2785 Less stack reserved per thread so that more threads can run
2786 concurrently. (Still 16M per thread.) [561]
2790 C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
2791 (works better when perl is running as service).
2795 Better UNC path handling under ithreads. [561]
2799 wait(), waitpid(), and backticks now return the correct exit status
2800 under Windows 9x. [561]
2804 A socket handle leak in accept() has been fixed. [561]
2810 =head1 New or Changed Diagnostics
2816 The lexical warnings category "deprecated" is no longer a sub-category
2817 of the "syntax" category. It is now a top-level category in its own
2822 All regular expression compilation error messages are now hopefully
2823 easier to understand both because the error message now comes before
2824 the failed regex and because the point of failure is now clearly
2825 marked by a C<E<lt>-- HERE> marker.
2829 The various "opened only for", "on closed", "never opened" warnings
2830 drop the C<main::> prefix for filehandles in the C<main> package,
2831 for example C<STDIN> instead of C<main::STDIN>.
2835 The "Unrecognized escape" warning has been extended to include C<\8>,
2836 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
2840 Two new debugging options have been added: if you have compiled your
2841 Perl with debugging, you can use the -DT [561] and -DR options to trace
2842 tokenising and to add reference counts to displaying variables,
2847 If an attempt to use a (non-blessed) reference as an array index
2848 is made, a warning is given.
2852 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2853 now give a warning. This may be a problem for generated and evaled
2858 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2859 using the C<"C"> format you will get an optional warning. Similarly
2860 for the C<"c"> format and a number less than -128 or more than 127.
2864 Certain regex modifiers such as C<(?o)> make sense only if applied to
2865 the entire regex. You will get an optional warning if you try to do
2870 Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
2871 has been deprecated for a while. Now you will get an optional warning.
2875 Using C<sort> in scalar context now issues an optional warning.
2876 This didn't do anything useful, as the sort was not performed.
2880 =head1 Changed Internals
2886 perlapi.pod (a companion to perlguts) now attempts to document the
2891 You can now build a really minimal perl called microperl.
2892 Building microperl does not require even running Configure;
2893 C<make -f Makefile.micro> should be enough. Beware: microperl makes
2894 many assumptions, some of which may be too bold; the resulting
2895 executable may crash or otherwise misbehave in wondrous ways.
2896 For careful hackers only.
2900 Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2901 ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2902 interfaces to the publicised API. For the full list of the available
2903 APIs see L<perlapi>.
2907 Made possible to propagate customised exceptions via croak()ing.
2911 Now xsubs can have attributes just like subs. (Well, at least the
2912 built-in attributes.)
2916 dTHR and djSP have been obsoleted; the former removed (because it's
2917 a no-op) and the latter replaced with dSP.
2921 PERL_OBJECT has been completely removed.
2925 The MAGIC constants (e.g. C<'P'>) have been macrofied
2926 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2927 and maintainability.
2931 The regex compiler now maintains a structure that identifies nodes in
2932 the compiled bytecode with the corresponding syntactic features of the
2933 original regex expression. The information is attached to the new
2934 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2935 complete information.
2939 The C code has been made much more C<gcc -Wall> clean. Some warning
2940 messages still remain in some platforms, so if you are compiling with
2941 gcc you may see some warnings about dubious practices. The warnings
2942 are being worked on.
2946 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2950 Documentation on how to use the Perl source repository has been added
2951 to F<Porting/repository.pod>.
2955 There are now several profiling make targets.
2959 =head1 Security Vulnerability Closed [561]
2961 (This change was already made in 5.7.0 but bears repeating here.)
2962 (5.7.0 came out before 5.6.1: the development branch 5.7 released
2963 earlier than the maintenance branch 5.6)
2965 A potential security vulnerability in the optional suidperl component
2966 of Perl was identified in August 2000. suidperl is neither built nor
2967 installed by default. As of November 2001 the only known vulnerable
2968 platform is Linux, most likely all Linux distributions. CERT and
2969 various vendors and distributors have been alerted about the vulnerability.
2970 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2971 for more information.
2973 The problem was caused by Perl trying to report a suspected security
2974 exploit attempt using an external program, /bin/mail. On Linux
2975 platforms the /bin/mail program had an undocumented feature which
2976 when combined with suidperl gave access to a root shell, resulting in
2977 a serious compromise instead of reporting the exploit attempt. If you
2978 don't have /bin/mail, or if you have 'safe setuid scripts', or if
2979 suidperl is not installed, you are safe.
2981 The exploit attempt reporting feature has been completely removed from
2982 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2983 from all the Perl 5.7 releases), so that particular vulnerability
2984 isn't there anymore. However, further security vulnerabilities are,
2985 unfortunately, always possible. The suidperl functionality is most
2986 probably going to be removed in Perl 5.10. In any case, suidperl
2987 should only be used by security experts who know exactly what they are
2988 doing and why they are using suidperl instead of some other solution
2989 such as sudo ( see http://www.courtesan.com/sudo/ ).
2993 Several new tests have been added, especially for the F<lib> and
2994 F<ext> subsections. There are now about 69 000 individual tests
2995 (spread over about 700 test scripts), in the regression suite (5.6.1
2996 has about 11 700 tests, in 258 test scripts) The exact numbers depend
2997 on the platform and Perl configuration used. Many of the new tests
2998 are of course introduced by the new modules, but still in general Perl
2999 is now more thoroughly tested.
3001 Because of the large number of tests, running the regression suite
3002 will take considerably longer time than it used to: expect the suite
3003 to take up to 4-5 times longer to run than in perl 5.6. On a really
3004 fast machine you can hope to finish the suite in about 6-8 minutes
3007 The tests are now reported in a different order than in earlier Perls.
3008 (This happens because the test scripts from under t/lib have been moved
3009 to be closer to the library/extension they are testing.)
3011 =head1 Known Problems
3019 If using the AIX native make command, instead of just "make" issue
3020 "make all". In some setups the former has been known to spuriously
3021 also try to run "make install". Alternatively, you may want to use
3026 In AIX 4.2, Perl extensions that use C++ functions that use statics
3027 may have problems in that the statics are not getting initialized.
3028 In newer AIX releases, this has been solved by linking Perl with
3029 the libC_r library, but unfortunately in AIX 4.2 the said library
3030 has an obscure bug where the various functions related to time
3031 (such as time() and gettimeofday()) return broken values, and
3032 therefore in AIX 4.2 Perl is not linked against libC_r.
3036 vac 5.0.0.0 May Produce Buggy Code For Perl
3038 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
3039 resulting in a few random tests failing when run as part of "make
3040 test", but when the failing tests are run by hand, they succeed.
3041 We suggest upgrading to at least vac version 5.0.1.0, that has been
3042 known to compile Perl correctly. "lslpp -L|grep vac.C" will tell
3043 you the vac version. See README.aix.
3047 If building threaded Perl, you may get compilation warning from pp_sys.c:
3049 "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
3051 This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()
3052 having slightly different types for their first argument.
3056 =head2 Alpha systems with old gccs fail several tests
3058 If you see op/pack, op/pat, op/regexp, or ext/Storable tests failing
3059 in a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc.
3060 gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 may
3061 be even better. (RedHat Linux/alpha with gcc 3.1 reported no problems,
3062 as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable to
3063 use the bundled C compiler.)
3067 Perl 5.8.0 doesn't build in AmigaOS. It broke at some point during
3068 the ithreads work and we could not find Amiga experts to unbreak the
3069 problems. Perl 5.6.1 still works for AmigaOS (as does the the 5.7.2
3070 development release).
3074 The following tests fail on 5.8.0 Perl in BeOS Personal 5.03:
3076 t/op/lfs............................FAILED at test 17
3077 t/op/magic..........................FAILED at test 24
3078 ext/Fcntl/t/syslfs..................FAILED at test 17
3079 ext/File/Glob/t/basic...............FAILED at test 3
3080 ext/POSIX/t/sigaction...............FAILED at test 13
3081 ext/POSIX/t/waitpid.................FAILED at test 1
3083 See L<perlbeos> (README.beos) for more details.
3085 =head2 Cygwin "unable to remap"
3087 For example when building the Tk extension for Cygwin,
3088 you may get an error message saying "unable to remap".
3089 This is known problem with Cygwin, and a workaround is
3090 detailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html
3092 =head2 Cygwin ndbm tests fail on FAT
3094 One can build but not install (or test the build of) the NDBM_File
3095 on FAT filesystems. Installation (or build) on NTFS works fine.
3097 =head2 ext/threads/t/libc
3099 If this test fails, it indicates that your libc (C library) is not
3100 threadsafe. This particular test stress tests the localtime() call to
3101 find out whether it is threadsafe. See L<perlthrtut> for more information.
3103 =head2 FreeBSD built with ithreads coredumps reading large directories
3105 This is a known bug in FreeBSD's readdir_r() (see L<perlfreebsd>
3106 (README.freebsd)), which hopefully will be fixed in FreeBSD 4.6.
3108 =head2 FreeBSD Failing locale Test 117 For ISO 8859-15 Locales
3110 The ISO 8859-15 locales may fail the locale test 117 in FreeBSD.
3111 This is caused by the characters \xFF (y with diaeresis) and \xBE
3112 (Y with diaeresis) not behaving correctly when being matched
3113 case-insensitively. Apparently this problem has been fixed in
3114 the latest FreeBSD releases.
3115 ( http://www.freebsd.org/cgi/query-pr.cgi?pr=34308 )
3117 =head2 IRIX fails ext/List/Util/t/shuffle.t
3119 IRIX with MIPSpro 7.3.1.3m compiler may fail the said List::Util test
3120 by dumping core. This seems to be a compiler error since if compiled
3121 with gcc no core dump ensues, and no failures on the said test on any
3124 =head2 Modifying $_ Inside for(..)
3128 works without complaint. It shouldn't. (You should be able to
3129 modify only lvalue elements inside the loops.) You can see the
3130 correct behaviour by replacing the 1..5 with 1, 2, 3, 4, 5.
3132 =head2 mod_perl 1.26 Doesn't Build With Threaded Perl
3134 Use mod_perl 1.27 or higher.
3136 =head2 lib/ftmp-security tests warn 'system possibly insecure'
3138 Don't panic. Read the 'make test' section of INSTALL instead.
3140 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
3142 If perl is configured with -Duse64bitall, the successful result of the
3143 subtest 10 of lib/posix may arrive before the successful result of the
3144 subtest 9, which confuses the test harness so much that it thinks the
3147 =head2 Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint
3149 This is a known bug in the glibc 2.2.5 with long long integers.
3150 ( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )
3152 =head2 Linux With Sfio Fails op/misc Test 48
3156 =head2 libwww-perl (LWP) fails base/date #51
3158 Use libwww-perl 5.65 or later.
3162 Please remember to set your environment variable LC_ALL to "C"
3163 (setenv LC_ALL C) before running "make test" to avoid a lot of
3164 warnings about the broken locales of Mac OS X.
3166 The following tests are known to fail in Mac OS X 10.1.5 because of
3167 buggy (old) implementations of Berkeley DB included in Mac OS X:
3169 Failed Test Stat Wstat Total Fail Failed List of Failed
3170 -------------------------------------------------------------------------
3171 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
3172 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
3174 If you are building on a UFS partition, you will also probably see
3175 t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not
3176 supporting inode change time.
3178 Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped for
3179 now because the failure is Apple's fault, not Perl's (blocked signals
3182 If you Configure with ithreads, ext/threads/t/libc.t will fail. Again,
3183 this is not Perl's fault-- the libc of Mac OS X is not threadsafe
3184 (in this particular test, the localtime() call is found to be
3187 =head2 OS/2 Test Failures
3189 The following tests are known to fail on OS/2 (for clarity
3190 only the failures are shown, not the full error messages):
3192 t/io/utf8............................FAILED at test 19
3193 t/op/grent...........................FAILED at test 2
3194 t/op/pwent...........................FAILED at test 1
3195 t/lib/os2_base.......................FAILED at test 13
3196 t/lib/os2_process....................FAILED at test 10
3197 t/lib/os2_process_kid................FAILED at test 10
3198 t/lib/rx_cmprt.......................FAILED at test 16
3199 ext/DB_File/t/db-btree...............FAILED at test 0
3200 ext/DB_File/t/db-hash................FAILED at test 0
3201 ext/DB_File/t/db-recno...............FAILED at test 0
3202 lib/ExtUtils/t/basic.................FAILED at test 14
3203 lib/ExtUtils/t/Constant..............FAILED at test 4
3204 lib/Memoize/t/errors.................FAILED at test 4
3206 =head2 op/sprintf tests 91, 129, and 130
3208 The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.
3209 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
3211 Test 91 is known to fail on QNX6 (nto), because C<sprintf '%e',0>
3212 incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>.
3214 For tests 129 and 130, the failing platforms do not comply with
3215 the ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, to
3216 be exact. (They produce something other than "1" and "-1" when
3217 formatting 0.6 and -0.6 using the printf format "%.0f"; most often,
3218 they produce "0" and "-0".)
3222 In case you are still using Solaris 2.5 (aka SunOS 5.5), you may
3223 experience failures (the test core dumping) in lib/locale.t.
3224 The suggested cure is to upgrade your Solaris.
3226 =head2 Solaris x86 Fails Tests With -Duse64bitint
3228 The following tests are known to fail in Solaris x86 with Perl
3229 configured to use 64 bit integers:
3231 ext/Data/Dumper/t/dumper.............FAILED at test 268
3232 ext/Devel/Peek/Peek..................FAILED at test 7
3234 =head2 SUPER-UX (NEC SX)
3236 The following tests are known to fail on SUPER-UX:
3238 op/64bitint...........................FAILED tests 29-30, 32-33, 35-36
3239 op/arith..............................FAILED tests 128-130
3240 op/pack...............................FAILED tests 25-5625
3241 op/pow................................
3242 op/taint..............................# msgsnd failed
3243 ../ext/IO/lib/IO/t/io_poll............FAILED tests 3-4
3244 ../ext/IPC/SysV/ipcsysv...............FAILED tests 2, 5-6
3245 ../ext/IPC/SysV/t/msg.................FAILED tests 2, 4-6
3246 ../ext/Socket/socketpair..............FAILED tests 12
3247 ../lib/IPC/SysV.......................FAILED tests 2, 5-6
3248 ../lib/warnings.......................FAILED tests 115-116, 118-119
3250 The op/pack failure ("Cannot compress negative numbers at op/pack.t line 126")
3251 is serious but as of yet unsolved. It points at some problems with the
3252 signedness handling of the C compiler, as do the 64bitint, arith, and pow
3253 failures. Most of the rest point at problems with SysV IPC.
3255 =head2 PDL failing some tests
3257 Use PDL 2.3.4 or later.
3259 =head2 Term::ReadKey not working on Win32
3261 Use Term::ReadKey 2.20 or later.
3263 =head2 Failure of Thread (5.005-style) tests
3265 B<Note that support for 5.005-style threading is deprecated,
3266 experimental and practically unsupported. In 5.10, it is expected
3267 to be removed. You should migrate your code to ithreads.>
3269 The following tests are known to fail due to fundamental problems in
3270 the 5.005 threading implementation. These are not new failures--Perl
3271 5.005_0x has the same bugs, but didn't have these tests.
3273 ../ext/B/t/xref.t 255 65280 14 12 85.71% 3-14
3274 ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7
3275 ../lib/English.t 2 512 54 2 3.70% 2-3
3276 ../lib/FileCache.t 5 1 20.00% 5
3277 ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3
3278 ../lib/Filter/Simple/t/filter_only. 9 3 33.33% 1-2 5
3279 ../lib/Math/BigInt/t/bare_mbf.t 1627 4 0.25% 8 11 1626-1627
3280 ../lib/Math/BigInt/t/bigfltpm.t 1629 4 0.25% 10 13 1628-
3282 ../lib/Math/BigInt/t/sub_mbf.t 1633 4 0.24% 8 11 1632-1633
3283 ../lib/Math/BigInt/t/with_sub.t 1628 4 0.25% 9 12 1627-1628
3284 ../lib/Tie/File/t/31_autodefer.t 255 65280 65 32 49.23% 34-65
3285 ../lib/autouse.t 10 1 10.00% 4
3286 op/flip.t 15 1 6.67% 15
3288 These failures are unlikely to get fixed as 5.005-style threads
3289 are considered fundamentally broken. (Basically what happens is that
3290 competing threads can corrupt shared global state, one good example
3291 being regular expression engine's state.)
3293 =head2 Timing problems
3295 The following tests may fail intermittently because of timing
3296 problems, for example if the system is heavily loaded.
3299 ext/Time/HiRes/HiRes.t
3301 lib/Memoize/t/expmod_t.t
3302 lib/Memoize/t/speed.t
3304 In case of failure please try running them manually, for example
3306 ./perl -Ilib ext/Time/HiRes/HiRes.t
3308 =head2 Unicode in package/class and subroutine names does not work
3310 One can have Unicode in identifier names, but not in package/class or
3311 subroutine names. While some limited functionality towards this does
3312 exist as of Perl 5.8.0, that is more accidental than designed; use of
3313 Unicode for the said purposes is unsupported.
3315 One reason of this unfinishedness is its (currently) inherent
3316 unportability: since both package names and subroutine names may
3317 need to be mapped to file and directory names, the Unicode capability
3318 of the filesystem becomes important-- and there unfortunately aren't
3327 During Configure, the test
3329 Guessing which symbols your C compiler and preprocessor define...
3331 will probably fail with error messages like
3333 CC-20 cc: ERROR File = try.c, Line = 3
3334 The identifier "bad" is undefined.
3336 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
3339 CC-65 cc: ERROR File = try.c, Line = 3
3340 A semicolon is expected at this point.
3342 This is caused by a bug in the awk utility of UNICOS/mk. You can ignore
3343 the error, but it does cause a slight problem: you cannot fully
3344 benefit from the h2ph utility (see L<h2ph>) that can be used to
3345 convert C headers to Perl libraries, mainly used to be able to access
3346 from Perl the constants defined using C preprocessor, cpp. Because of
3347 the above error, parts of the converted headers will be invisible.
3348 Luckily, these days the need for h2ph is rare.
3352 If building Perl with interpreter threads (ithreads), the
3353 getgrent(), getgrnam(), and getgrgid() functions cannot return the
3354 list of the group members due to a bug in the multithreaded support of
3355 UNICOS/mk. What this means is that in list context the functions will
3356 return only three values, not four.
3362 There are a few known test failures, see L<perluts> (README.uts).
3364 =head2 VOS (Stratus)
3366 When Perl is built using the native build process on VOS Release
3367 14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests either
3368 pass or result in TODO (ignored) failures.
3372 There should be no reported test failures with a default configuration,
3373 though there are a number of tests marked TODO that point to areas
3374 needing further debugging and/or porting work.
3378 In multi-CPU boxes, there are some problems with the I/O buffering:
3379 some output may appear twice.
3381 =head2 XML::Parser not working
3383 Use XML::Parser 2.31 or later.
3385 =head2 z/OS (OS/390)
3387 z/OS has rather many test failures but the situation is actually
3388 better than it was in 5.6.0; it's just that so many new modules and
3389 tests have been added.
3391 Failed Test Stat Wstat Total Fail Failed List of Failed
3392 ---------------------------------------------------------------------------
3393 ../ext/Data/Dumper/t/dumper.t 357 8 2.24% 311 314 325 327
3395 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5
3396 ../ext/Storable/t/downgrade.t 12 3072 169 12 7.10% 14-15 46-47 78-79
3398 ../lib/ExtUtils/t/Constant.t 121 30976 48 48 100.00% 1-48
3399 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9
3400 op/pat.t 0 11 922 283 30.69% 640-922
3401 op/sprintf.t 224 3 1.34% 98 100 136
3402 op/tr.t 97 5 5.15% 63 71-74
3403 uni/fold.t 780 6 0.77% 61 169 196 661
3406 The failures in dumper.t and downgrade.t are problems in the tests,
3407 those in io_unix and sprintf are problems in the USS (UDP sockets and
3408 printf formats). The pat, tr, and fold failures are genuine Perl
3409 problems caused by EBCDIC (and in the pat and fold cases, combining
3410 that with Unicode). The Constant and Embed are probably problems in
3411 the tests (since they test Perl's ability to build extensions, and
3412 that seems to be working reasonably well.)
3414 =head2 Localising Tied Arrays and Hashes Is Broken
3418 doesn't work as one would expect: the old value is restored
3419 incorrectly. This will be changed in a future release, but we don't
3420 know yet what the new semantics will exactly be. In any case, the
3421 change will break existing code that relies on the current
3422 (ill-defined) semantics, so just avoid doing this in general.
3424 =head2 Self-tying Problems
3426 Self-tying of arrays and hashes is broken in rather deep and
3427 hard-to-fix ways. As a stop-gap measure to avoid people from getting
3428 frustrated at the mysterious results (core dumps, most often), it is
3429 forbidden for now (you will get a fatal error even from an attempt).
3431 A change to self-tying of globs has caused them to be recursively
3432 referenced (see: L<perlobj/"Two-Phased Garbage Collection">). You
3433 will now need an explicit untie to destroy a self-tied glob. This
3434 behaviour may be fixed at a later date.
3436 Self-tying of scalars and IO thingies works.
3438 =head2 Tied/Magical Array/Hash Elements Do Not Autovivify
3440 For normal arrays C<$foo = \$bar[1]> will assign C<undef> to
3441 C<$bar[1]> (assuming that it didn't exist before), but for
3442 tied/magical arrays and hashes such autovivification does not happen
3443 because there is currently no way to catch the reference creation.
3444 The same problem affects slicing over non-existent indices/keys of
3445 a tied/magical array/hash.
3447 =head2 Building Extensions Can Fail Because Of Largefiles
3449 Some extensions like mod_perl are known to have issues with
3450 `largefiles', a change brought by Perl 5.6.0 in which file offsets
3451 default to 64 bits wide, where supported. Modules may fail to compile
3452 at all, or they may compile and work incorrectly. Currently, there
3453 is no good solution for the problem, but Configure now provides
3454 appropriate non-largefile ccflags, ldflags, libswanted, and libs
3455 in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the
3456 extensions that are having problems can try configuring themselves
3457 without the largefileness. This is admittedly not a clean solution,
3458 and the solution may not even work at all. One potential failure is
3459 whether one can (or, if one can, whether it's a good idea to) link
3460 together at all binaries with different ideas about file offsets;
3461 all this is platform-dependent.
3463 =head2 Unicode Support on EBCDIC Still Spotty
3465 Though mostly working, Unicode support still has problem spots on
3466 EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
3467 regular expression constructs for code points less than 256: the
3468 C<pP> are testing for Unicode code points, not knowing about EBCDIC.
3470 =head2 The Compiler Suite Is Still Very Experimental
3472 The compiler suite is slowly getting better but it continues to be
3473 highly experimental. Use in production environments is discouraged.
3475 =head2 The Long Double Support Is Still Experimental
3477 The ability to configure Perl's numbers to use "long doubles",
3478 floating point numbers of hopefully better accuracy, is still
3479 experimental. The implementations of long doubles are not yet
3480 widespread and the existing implementations are not quite mature
3481 or standardised, therefore trying to support them is a rare
3482 and moving target. The gain of more precision may also be offset
3483 by slowdown in computations (more bits to move around, and the
3484 operations are more likely to be executed by less optimised
3487 =head2 Seen In Perl 5.7 But Gone Now
3489 C<Time::Piece> (previously known as C<Time::Object>) was removed
3490 because it was felt that it didn't have enough value in it to be a
3491 core module. It is still a useful module, though, and is available
3494 Perl 5.8 unfortunately does not build anymore on AmigaOS; this broke
3495 accidentally at some point. Since there are not that many Amiga
3496 developers available, we could not get this fixed and tested in time
3497 for 5.8.0. Perl 5.6.1 still works for AmigaOS (as does the the 5.7.2
3498 development release).
3500 The C<PerlIO::Scalar> and C<PerlIO::Via> (capitalised) were renamed as
3501 C<PerlIO::scalar> and C<PerlIO::via> (all lowercase) just before 5.8.0.
3502 The main rationale was to have all core IO layers to have all
3503 lowercase names. The "plugins" are named as usual, for example
3504 C<PerlIO::via::QuotedPrint>.
3506 =head1 Reporting Bugs
3508 If you find what you think is a bug, you might check the articles
3509 recently posted to the comp.lang.perl.misc newsgroup and the perl
3510 bug database at http://bugs.perl.org/ . There may also be
3511 information at http://www.perl.com/ , the Perl Home Page.
3513 If you believe you have an unreported bug, please run the B<perlbug>
3514 program included with your release. Be sure to trim your bug down
3515 to a tiny but sufficient test case. Your bug report, along with the
3516 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3517 analysed by the Perl porting team.
3521 The F<Changes> file for exhaustive details on what changed.
3523 The F<INSTALL> file for how to build Perl.
3525 The F<README> file for general stuff.
3527 The F<Artistic> and F<Copying> files for copyright information.
3531 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.