This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
VMS test and perldelta update
[perl5.git] / pod / perldelta.pod
CommitLineData
ba370e9b 1=head1 NAME
cc0fca54 2
f39f21d8 3perldelta - what is new for perl v5.8.0
cc0fca54
GS
4
5=head1 DESCRIPTION
6
44da0e71
JH
7This document describes differences between the 5.6.0 release
8and the 5.8.0 release.
f39f21d8 9
44da0e71
JH
10Many of the bug fixes in 5.8.0 were already seen in the 5.6.1
11maintenance release since the two releases were kept closely
12coordinated.
13
4f8e5944
JH
14If you are upgrading from Perl 5.005_03, you might also want
15to read L<perl56delta>.
16
44da0e71 17=head1 Highlights In 5.8.0
76663d67
JH
18
19=over 4
20
21=item *
22
23Better Unicode support
24
25=item *
26
27New Thread Implementation
28
29=item *
30
31Many New Modules
32
33=item *
34
35Better Numeric Accuracy
36
37=item *
38
39Safe Signals
40
41=item *
42
43More Extensive Regression Testing
44
45=back
46
f39f21d8
JH
47=head1 Incompatible Changes
48
77c8cf41
JH
49=head2 64-bit platforms and malloc
50
057b7f2b 51If your pointers are 64 bits wide, the Perl malloc is no longer being
c2e23569 52used because it does not work well with 8-byte pointers. Also,
61947107 53usually the system mallocs on such platforms are much better optimized
c2e23569
JH
54for such large memory models than the Perl malloc. Some memory-hungry
55Perl applications like the PDL don't work well with Perl's malloc.
56Finally, other applications than Perl (like modperl) tend to prefer
57the system malloc. Such platforms include Alpha and 64-bit HPPA,
58MIPS, PPC, and Sparc.
77c8cf41
JH
59
60=head2 AIX Dynaloading
61
62The AIX dynaloading now uses in AIX releases 4.3 and newer the native
63dlopen interface of AIX instead of the old emulated interface. This
64change will probably break backward compatibility with compiled
65modules. The change was made to make Perl more compliant with other
66applications like modperl which are using the AIX native interface.
67
95f0a2f1
SB
68=head2 Attributes for C<my> variables now handled at run-time.
69
70The C<my EXPR : ATTRS> syntax now applies variable attributes at
71run-time. (Subroutine and C<our> variables still get attributes applied
72at compile-time.) See L<attributes> for additional details. In particular,
73however, this allows variable attributes to be useful for C<tie> interfaces,
c4f1ce08
JH
74which was a deficiency of earlier releases. Note that the new semantics
75doesn't work with the Attribute::Handlers module (as of version 0.76).
95f0a2f1 76
77c8cf41
JH
77=head2 Socket Extension Dynamic in VMS
78
79The Socket extension is now dynamically loaded instead of being
80statically built in. This may or may not be a problem with ancient
81TCP/IP stacks of VMS: we do not know since we weren't able to test
82Perl in such configurations.
83
00bb525a
CB
84=head2 IEEE-format Floating Point Default on OpenVMS Alpha
85
86Perl now uses IEEE format (T_FLOAT) as the default internal floating
87point format on OpenVMS Alpha, potentially breaking binary compatibility
88with external libraries or existing data. G_FLOAT is still available as
89a configuration option. The default on VAX (D_FLOAT) has not changed.
90
eb0cc9e3
JH
91=head2 New Unicode Properties
92
93Unicode I<scripts> are now supported. Scripts are similar to (and superior
94to) Unicode I<blocks>. The difference between scripts and blocks is that
95scripts are the glyphs used by a language or a group of languages, while
96the blocks are more artificial groupings of (mostly) 256 characters based
97on the Unicode numbering.
98
99In general, scripts are more inclusive, but not universally so. For
100example, while the script C<Latin> includes all the Latin characters and
101their various diacritic-adorned versions, it does not include the various
102punctuation or digits (since they are not solely C<Latin>).
103
104A number of other properties are now supported, including C<\p{L&}>,
105C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> and
106C<\p{SpacePerl}> (along with their C<\P{...}> versions, of course).
107See L<perlunicode> for details, and more additions.
108
109The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
110are now almost always optional. The only exception is that a C<In> prefix
111is required to signify a Unicode block when a block name conflicts with a
112script name. For example, C<\p{Tibetan}> refers to the script, while
113C<\p{InTibetan}> refers to the block. When there is no name conflict, you
114can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
115to be safe, it's probably best to always use the C<In>).
77c8cf41 116
61947107
JH
117=head2 Perl Parser Stress Tested
118
119The Perl parser has been stress tested using both random input and
120Markov chain input and the few found crashes and lockups have been
121fixed.
122
c2e23569 123=head2 REF(...) Instead Of SCALAR(...)
77c8cf41 124
057b7f2b 125A reference to a reference now stringifies as "REF(0x81485ec)" instead
c2e23569
JH
126of "SCALAR(0x81485ec)" in order to be more consistent with the return
127value of ref().
77c8cf41 128
79f69e33
JH
129=head2 pack/unpack D/F recycled
130
66023b77 131The undocumented pack/unpack template letters D/F have been recycled
79f69e33
JH
132for better use: now they stand for long double (if supported by the
133platform) and NV (Perl internal floating point type). (They used
134to be aliases for f/d, but you never knew that.)
135
c2e23569 136=head2 Deprecations
77c8cf41 137
61947107 138=over 4
77c8cf41 139
61947107 140=item *
f39f21d8 141
61947107
JH
142The semantics of bless(REF, REF) were unclear and until someone proves
143it to make some sense, it is forbidden.
f39f21d8
JH
144
145=item *
146
c2e23569
JH
147The obsolete chat2 library that should never have been allowed
148to escape the laboratory has been decommissioned.
f39f21d8
JH
149
150=item *
151
58175c9b
JH
152The builtin dump() function has probably outlived most of its
153usefulness. The core-dumping functionality will remain in future
154available as an explicit call to C<CORE::dump()>, but in future
155releases the behaviour of an unqualified C<dump()> call may change.
156
157=item *
158
61947107
JH
159The very dusty examples in the eg/ directory have been removed.
160Suggestions for new shiny examples welcome but the main issue is that
161the examples need to be documented, tested and (most importantly)
162maintained.
f39f21d8
JH
163
164=item *
165
c2e23569
JH
166The (bogus) escape sequences \8 and \9 now give an optional warning
167("Unrecognized escape passed through"). There is no need to \-escape
168any C<\w> character.
f39f21d8
JH
169
170=item *
171
c2e23569 172The list of filenames from glob() (or <...>) is now by default sorted
44da0e71
JH
173alphabetically to be csh-compliant (which is what happened before
174in most UNIX platforms). (bsd_glob() does still sort platform
c2e23569 175natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
f39f21d8
JH
176
177=item *
178
44da0e71
JH
179Spurious syntax errors generated in certain situations, when glob()
180caused File::Glob to be loaded for the first time, have been fixed.
181
182=item *
183
c2e23569
JH
184Although "you shouldn't do that", it was possible to write code that
185depends on Perl's hashed key order (Data::Dumper does this). The new
186algorithm "One-at-a-Time" produces a different hashed key order.
187More details are in L</"Performance Enhancements">.
f39f21d8
JH
188
189=item *
190
61947107
JH
191lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
192In future releases this may become a fatal error.
f39f21d8
JH
193
194=item *
195
057b7f2b 196The C<package;> syntax (C<package> without an argument) has been
c2e23569
JH
197deprecated. Its semantics were never that clear and its
198implementation even less so. If you have used that feature to
199disallow all but fully qualified variables, C<use strict;> instead.
61947107
JH
200
201=item *
202
c2e23569
JH
203The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
204recognised but now cause fatal errors. The previous behaviour of
205ignoring them by default and warning if requested was unacceptable
206since it, in a way, falsely promised that the features could be used.
61947107
JH
207
208=item *
209
c2e23569
JH
210The current user-visible implementation of pseudo-hashes (the weird
211use of the first array element) is deprecated starting from Perl 5.8.0
212and will be removed in Perl 5.10.0, and the feature will be
213implemented differently. Not only is the current interface rather
214ugly, but the current implementation slows down normal array and hash
215use quite noticeably. The C<fields> pragma interface will remain
216available.
61947107
JH
217
218=item *
219
aecce728 220The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
61947107
JH
221
222=item *
223
c2e23569
JH
224After years of trying the suidperl is considered to be too complex to
225ever be considered truly secure. The suidperl functionality is likely
226to be removed in a future release.
227
228=item *
229
230The long deprecated uppercase aliases for the string comparison
231operators (EQ, NE, LT, LE, GE, GT) have now been removed.
232
233=item *
234
235The tr///C and tr///U features have been removed and will not return;
236the interface was a mistake. Sorry about that. For similar
237functionality, see pack('U0', ...) and pack('C0', ...).
f39f21d8 238
420cdfc1
ST
239=item *
240
241Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
242The prototypes are now checked at compile-time for invalid characters.
243An optional warning is generated ("Illegal character in prototype...")
244but this may be upgraded to a fatal error in a future release.
245
f39f21d8
JH
246=back
247
61947107
JH
248=head1 Core Enhancements
249
77c8cf41 250=head2 PerlIO is Now The Default
f39f21d8
JH
251
252=over 4
253
254=item *
255
77c8cf41
JH
256IO is now by default done via PerlIO rather than system's "stdio".
257PerlIO allows "layers" to be "pushed" onto a file handle to alter the
258handle's behaviour. Layers can be specified at open time via 3-arg
259form of open:
f39f21d8 260
77c8cf41 261 open($fh,'>:crlf :utf8', $path) || ...
f39f21d8 262
77c8cf41 263or on already opened handles via extended C<binmode>:
f39f21d8 264
77c8cf41 265 binmode($fh,':encoding(iso-8859-7)');
f39f21d8 266
77c8cf41
JH
267The built-in layers are: unix (low level read/write), stdio (as in
268previous Perls), perlio (re-implementation of stdio buffering in a
269portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
270but available on any platform). A mmap layer may be available if
271platform supports it (mostly UNIXes).
f39f21d8 272
77c8cf41
JH
273Layers to be applied by default may be specified via the 'open' pragma.
274
275See L</"Installation and Configuration Improvements"> for the effects
276of PerlIO on your architecture name.
f39f21d8
JH
277
278=item *
279
77c8cf41
JH
280File handles can be marked as accepting Perl's internal encoding of Unicode
281(UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
f39f21d8 282
77c8cf41 283 open($fh,">:utf8","Uni.txt");
f39f21d8 284
77c8cf41
JH
285Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
286for you since it's not UTF-8 what you will be getting but instead
287UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
288http://www.unicode.org/unicode/reports/tr16/ for more information.
289In future releases this naming may change.
f39f21d8
JH
290
291=item *
292
77c8cf41
JH
293File handles can translate character encodings from/to Perl's internal
294Unicode form on read/write via the ":encoding()" layer.
f39f21d8
JH
295
296=item *
297
77c8cf41
JH
298File handles can be opened to "in memory" files held in Perl scalars via:
299
300 open($fh,'>', \$variable) || ...
f39f21d8
JH
301
302=item *
303
77c8cf41
JH
304Anonymous temporary files are available without need to
305'use FileHandle' or other module via
f39f21d8 306
77c8cf41 307 open($fh,"+>", undef) || ...
f39f21d8 308
77c8cf41 309That is a literal undef, not an undefined value.
f39f21d8
JH
310
311=item *
312
77c8cf41 313The list form of C<open> is now implemented for pipes (at least on UNIX):
f39f21d8 314
77c8cf41 315 open($fh,"-|", 'cat', '/etc/motd')
f39f21d8 316
77c8cf41
JH
317creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
318the child process.
f39f21d8 319
e1f170bd 320=back
f39f21d8 321
3e33716f 322=head2 Safe Signals
f39f21d8 323
e1f170bd
JH
324Perl used to be fragile in that signals arriving at inopportune moments
325could corrupt Perl's internal state. Now Perl postpones handling of
3e33716f
JH
326signals until it's safe (between opcodes).
327
56e5bb57 328This change may have surprising side effects because signals no longer
3e33716f
JH
329interrupt Perl instantly. Perl will now first finish whatever it was
330doing, like finishing an internal operation (like sort()) or an
331external operation (like an I/O operation), and only then look at any
332arrived signals (and before starting the next operation). No more corrupt
333internal state since the current operation is always finished first,
334but the signal may take more time to get heard.
f39f21d8 335
e1f170bd 336=head2 Unicode Overhaul
f39f21d8 337
e1f170bd
JH
338Unicode in general should be now much more usable than in Perl 5.6.0
339(or even in 5.6.1). Unicode can be used in hash keys, Unicode in
340regular expressions should work now, Unicode in tr/// should work now,
341Unicode in I/O should work now.
f39f21d8 342
e1f170bd 343=over 4
f39f21d8
JH
344
345=item *
346
e1f170bd
JH
347The Unicode Character Database coming with Perl has been upgraded
348to Unicode 3.1.1. For more information, see http://www.unicode.org/.
f39f21d8
JH
349
350=item *
351
77c8cf41
JH
352For developers interested in enhancing Perl's Unicode capabilities:
353almost all the UCD files are included with the Perl distribution in
58175c9b 354the F<lib/unicore subdirectory>. The most notable omission, for space
77c8cf41 355considerations, is the Unihan database.
f39f21d8
JH
356
357=item *
358
eb0cc9e3
JH
359The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like
360C isblank(), that is, it contains only "horizontal whitespace" (the space
361character is, the newline isn't), and the "SpacePerl" is the Unicode
362equivalent of C<\s> (\p{Space} isn't, since that includes the vertical
363tabulator character, whereas C<\s> doesn't.)
364
365See "New Unicode Properties" earlier in this document for additional
366information on changes with Unicode properties.
f39f21d8
JH
367
368=back
369
77c8cf41
JH
370=head2 Understanding of Numbers
371
372In general a lot of fixing has happened in the area of Perl's
373understanding of numbers, both integer and floating point. Since in
374many systems the standard number parsing functions like C<strtoul()>
375and C<atof()> seem to have bugs, Perl tries to work around their
376deficiencies. This results hopefully in more accurate numbers.
f39f21d8 377
e1f170bd
JH
378Perl now tries internally to use integer values in numeric conversions
379and basic arithmetics (+ - * /) if the arguments are integers, and
380tries also to keep the results stored internally as integers.
057b7f2b 381This change leads to often slightly faster and always less lossy
e1f170bd
JH
382arithmetics. (Previously Perl always preferred floating point numbers
383in its math.)
384
58175c9b 385=head2 Miscellaneous Changes
e1f170bd 386
f39f21d8
JH
387=over 4
388
389=item *
390
e1f170bd
JH
391AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
392to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
393
394=item *
395
61947107
JH
396C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
397in multiple arguments.)
f39f21d8
JH
398
399=item *
400
58175c9b 401The builtin dump() now gives an optional warning
66023b77 402C<dump() better written as CORE::dump()>,
58175c9b
JH
403meaning that by default C<dump(...)> is resolved as the builtin
404dump() which dumps core and aborts, not as (possibly) user-defined
405C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
406(The whole dump() feature is to considered deprecated, and possibly
407removed/changed in future releases.)
408
409=item *
410
66023b77 411chomp() and chop() have been demoted back to I<not> being overridable
58175c9b
JH
412because they cannot really be overridden-- the problem is that their
413prototype cannot be expressed and therefore one really cannot write
414replacements to override these builtins.
415
416=item *
417
61947107
JH
418END blocks are now run even if you exit/die in a BEGIN block.
419Internally, the execution of END blocks is now controlled by
420PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
421behaviour for Perl embedders. This will default in 5.10. See
422L<perlembed>.
f39f21d8
JH
423
424=item *
425
e1f170bd 426Formats now support zero-padded decimal fields.
f39f21d8
JH
427
428=item *
429
77c8cf41 430Lvalue subroutines can now return C<undef> in list context.
44da0e71 431However, the lvalue subroutine feature still remains experimental.
f39f21d8
JH
432
433=item *
434
58175c9b
JH
435A lost warning "Can't declare ... dereference in my" has been
436restored (Perl had it earlier but it became lost in later releases.)
437
438=item *
439
61947107
JH
440A new special regular expression variable has been introduced:
441C<$^N>, which contains the most-recently closed group (submatch).
f39f21d8
JH
442
443=item *
444
61947107 445C<no Module;> now works even if there is no "sub unimport" in the Module.
f39f21d8
JH
446
447=item *
448
61947107
JH
449The numerical comparison operators return C<undef> if either operand
450is a NaN. Previously the behaviour was unspecified.
f39f21d8
JH
451
452=item *
453
e1f170bd
JH
454The following builtin functions are now overridable: each(), keys(),
455pop(), push(), shift(), splice(), unshift().
456
457=item *
458
a7bac030
JH
459C<pack() / unpack()> now can group template letters with C<()> and then
460apply repetition/count modifiers on the groups.
461
462=item *
463
464C<pack() / unpack()> can now process the Perl internal numeric types:
465IVs, UVs, NVs-- and also long doubles, if supported by the platform.
79f69e33 466The template letters are C<j>, C<J>, C<F>, and C<D>.
a7bac030
JH
467
468=item *
469
61947107 470C<pack('U0a*', ...)> can now be used to force a string to UTF8.
f39f21d8
JH
471
472=item *
473
61947107 474my __PACKAGE__ $obj now works.
f39f21d8
JH
475
476=item *
477
e1f170bd
JH
478The printf() and sprintf() now support parameter reordering using the
479C<%\d+\$> and C<*\d+\$> syntaxes. For example
480
481 print "%2\$s %1\$s\n", "foo", "bar";
482
da6838c8
JH
483will print "bar foo\n". This feature helps in writing
484internationalised software, and in general when the order
485of the parameters can vary.
f39f21d8
JH
486
487=item *
488
e1f170bd 489prototype(\&) is now available.
61947107
JH
490
491=item *
492
e1f170bd
JH
493prototype(\[$@%&]) is now available to implicitly create references
494(useful for example if you want to emulate the tie() interface).
61947107
JH
495
496=item *
497
58175c9b
JH
498A new command-line option, C<-t> is available. It is the
499little brother of C<-T>: instead of dieing on taint violations,
500lexical warnings are given. B<This is only meant as a temporary
501debugging aid while securing the code of old legacy applications.
502This is not a substitute for -T.>
503
504=item *
505
4956848f
JH
506In other taint news, the C<exec LIST> and C<system LIST> have now been
507considered too risky (think C<exec @ARGV>: it can start any program
508with any arguments), and now the said forms cause a warning.
509You should carefully launder the arguments to guarantee their
510validity. In future releases of Perl the forms will become fatal
511errors so consider starting laundering now.
512
513=item *
514
58175c9b
JH
515If tr/// is just counting characters, it doesn't attempt to
516modify its target.
517
518=item *
519
44da0e71
JH
520untie() will now call an UNTIE() hook if it exists. See L<perltie>
521for details.
61947107
JH
522
523=item *
524
525L<utime> now supports C<utime undef, undef, @files> to change the
526file timestamps to the current time.
527
528=item *
529
e1f170bd
JH
530The rules for allowing underscores (underbars) in numeric constants
531have been relaxed and simplified: now you can have an underscore
532simply B<between digits>.
f39f21d8
JH
533
534=back
535
77c8cf41 536=head1 Modules and Pragmata
f39f21d8 537
1e13d81f 538=head2 New Modules and Pragmata
f39f21d8
JH
539
540=over 4
541
542=item *
543
0e9b9e0c
JH
544C<Attribute::Handlers> allows a class to define attribute handlers.
545
546 package MyPack;
547 use Attribute::Handlers;
548 sub Wolf :ATTR(SCALAR) { print "howl!\n" }
549
550 # later, in some package using or inheriting from MyPack...
551
552 my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
553
554Both variables and routines can have attribute handlers. Handlers can
555be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
556exact compilation phase (BEGIN, CHECK, INIT, or END).
557
558=item *
559
61947107
JH
560B<B::Concise> is a new compiler backend for walking the Perl syntax
561tree, printing concise info about ops, from Stephen McCamant. The
562output is highly customisable. See L<B::Concise>.
f39f21d8
JH
563
564=item *
565
61947107
JH
566C<Class::ISA> for reporting the search path for a class's ISA tree,
567by Sean Burke, has been added. See L<Class::ISA>.
f39f21d8
JH
568
569=item *
570
61947107
JH
571C<Cwd> has now a split personality: if possible, an XS extension is
572used, (this will hopefully be faster, more secure, and more robust)
573but if not possible, the familiar Perl implementation is used.
f39f21d8
JH
574
575=item *
576
e1f170bd
JH
577C<Devel::PPPort>, originally from Kenneth Albanowski and now
578maintained by Paul Marquess, has been added. It is primarily used
66023b77 579by C<h2xs> to enhance portability of XS modules between different
e1f170bd 580versions of Perl.
1e13d81f
JH
581
582=item *
583
61947107
JH
584C<Digest>, frontend module for calculating digests (checksums), from
585Gisle Aas, has been added. See L<Digest>.
f39f21d8
JH
586
587=item *
588
61947107
JH
589C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
590RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
f39f21d8
JH
591
592 use Digest::MD5 'md5_hex';
593
594 $digest = md5_hex("Thirsty Camel");
595
596 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
597
61947107 598NOTE: the C<MD5> backward compatibility module is deliberately not
e1f170bd 599included since its further use is discouraged.
f39f21d8 600
f39f21d8
JH
601=item *
602
61947107 603C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
f39f21d8
JH
604between different character encodings. Support for Unicode,
605ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
606compiled in to the module. Several other encodings (like Japanese,
607Chinese, and MacIntosh encodings) are included and will be loaded at
61947107 608runtime. See L<Encode>.
f39f21d8
JH
609
610Any encoding supported by Encode module is also available to the
611":encoding()" layer if PerlIO is used.
612
61947107
JH
613=item *
614
615C<I18N::Langinfo> can be use to query locale information.
616See L<I18N::Langinfo>.
f39f21d8
JH
617
618=item *
619
61947107 620C<I18N::LangTags> has functions for dealing with RFC3066-style
bea4d472 621language tags, by Sean Burke. See L<I18N::LangTags>.
61947107
JH
622
623=item *
624
625C<ExtUtils::Constant> is a new tool for extension writers for
626generating XS code to import C header constants, by Nicholas Clark.
627See L<ExtUtils::Constant>.
628
629=item *
630
631C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
632from Damian Conway. See L<Filter::Simple>.
f39f21d8
JH
633
634 # in MyFilter.pm:
635
636 package MyFilter;
637
638 use Filter::Simple sub {
639 while (my ($from, $to) = splice @_, 0, 2) {
640 s/$from/$to/g;
641 }
642 };
643
644 1;
645
646 # in user's code:
647
648 use MyFilter qr/red/ => 'green';
649
650 print "red\n"; # this code is filtered, will print "green\n"
651 print "bored\n"; # this code is filtered, will print "bogreen\n"
652
653 no MyFilter;
654
655 print "red\n"; # this code is not filtered, will print "red\n"
656
61947107
JH
657=item *
658
659C<File::Temp> allows one to create temporary files and directories in
660an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
661
662=item *
663
664C<Filter::Util::Call> provides you with the framework to write
665I<Source Filters> in Perl, from Paul Marquess. For most uses the
666frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
667
668=item *
669
79f69e33
JH
670C<if> is a new pragma for conditional inclusion of modules, from
671Ilya Zakharevich.
672
673=item *
674
61947107
JH
675L<libnet> is a collection of perl5 modules related to network
676programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
677L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
678
679Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
f39f21d8
JH
680
681=item *
682
61947107 683C<List::Util> is a selection of general-utility list subroutines, like
bea4d472 684sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
f39f21d8
JH
685
686=item *
687
61947107
JH
688C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
689C<Locale::Language>, from Neil Bowers, have been added. They provide the
690codes for various locale standards, such as "fr" for France, "usd" for
691US Dollar, and "jp" for Japanese.
f39f21d8
JH
692
693 use Locale::Country;
694
695 $country = code2country('jp'); # $country gets 'Japan'
696 $code = country2code('Norway'); # $code gets 'no'
697
698See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
61947107
JH
699and L<Locale::Language>.
700
701=item *
702
703C<Locale::Maketext> is localization framework from Sean Burke. See
704L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
705article about software localization, originally published in The Perl
706Journal #13, republished here with kind permission.
707
708=item *
709
710C<Memoize> can make your functions faster by trading space for time,
711from Mark-Jason Dominus. See L<Memoize>.
f39f21d8
JH
712
713=item *
714
61947107
JH
715C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
716as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
717Extensions)>.
f39f21d8
JH
718
719 use MIME::Base64;
720
721 $encoded = encode_base64('Aladdin:open sesame');
722 $decoded = decode_base64($encoded);
723
724 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
725
61947107 726See L<MIME::Base64>.
f39f21d8
JH
727
728=item *
729
61947107
JH
730C<MIME::QuotedPrint> allows you to encode data in quoted-printable
731encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
732Extensions)>, from Gisle Aas.
f39f21d8
JH
733
734 use MIME::QuotedPrint;
735
736 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
737 $decoded = decode_qp($encoded);
738
739 print $encoded, "\n"; # "Smiley in Unicode: =263A"
740
741MIME::QuotedPrint has been enhanced to provide the basic methods
742necessary to use it with PerlIO::Via as in :
743
744 use MIME::QuotedPrint;
057b7f2b 745 open($fh,">Via(MIME::QuotedPrint)",$path);
f39f21d8 746
61947107 747See L<MIME::QuotedPrint>.
f39f21d8
JH
748
749=item *
750
61947107
JH
751C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
752See L<NEXT>.
f39f21d8
JH
753
754=item *
755
1e13d81f
JH
756C<open> is a new pragma for setting the default I/O disciplines
757for open().
758
759=item *
760
61947107
JH
761C<PerlIO::Scalar> provides the implementation of IO to "in memory"
762Perl scalars as discussed above, from Nick Ing-Simmons. It also
763serves as an example of a loadable PerlIO layer. Other future
764possibilities include PerlIO::Array and PerlIO::Code.
765See L<PerlIO::Scalar>.
766
767=item *
768
769C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
770functionality provided by a class (typically implemented in perl
771code), from Nick Ing-Simmons.
f39f21d8
JH
772
773 use MIME::QuotedPrint;
057b7f2b 774 open($fh,">Via(MIME::QuotedPrint)",$path);
f39f21d8
JH
775
776This will automatically convert everything output to C<$fh>
61947107 777to Quoted-Printable. See L<PerlIO::Via>.
f39f21d8
JH
778
779=item *
780
1e13d81f 781C<Pod::ParseLink>, by Russ Allbery, has been added,
95f0a2f1 782to parse LZ<><> links in pods as described in the new
1e13d81f
JH
783perlpodspec.
784
785=item *
786
61947107 787C<Pod::Text::Overstrike>, by Joe Smith, has been added.
f39f21d8 788It converts POD data to formatted overstrike text.
61947107 789See L<Pod::Text::Overstrike>.
f39f21d8
JH
790
791=item *
792
61947107
JH
793C<Scalar::Util> is a selection of general-utility scalar subroutines,
794like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
795
796=item *
797
1e13d81f
JH
798C<sort> is a new pragma for controlling the behaviour of sort().
799
800=item *
801
61947107
JH
802C<Storable> gives persistence to Perl data structures by allowing the
803storage and retrieval of Perl data to and from files in a fast and
804compact binary format, from Raphael Manfredi. See L<Storable>.
805
806=item *
807
808C<Switch>, from Damian Conway, has been added. Just by saying
f39f21d8
JH
809
810 use Switch;
811
812you have C<switch> and C<case> available in Perl.
813
814 use Switch;
815
816 switch ($val) {
817
818 case 1 { print "number 1" }
819 case "a" { print "string a" }
820 case [1..10,42] { print "number in list" }
821 case (@array) { print "number in list" }
822 case /\w+/ { print "pattern" }
823 case qr/\w+/ { print "pattern" }
824 case (%hash) { print "entry in hash" }
825 case (\%hash) { print "entry in hash" }
826 case (\&sub) { print "arg to subroutine" }
827 else { print "previous case not true" }
828 }
829
61947107
JH
830See L<Switch>.
831
832=item *
833
834C<Test::More> is yet another framework for writing test scripts,
835more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
836
837=item *
838
aecce728 839C<Test::Simple> has basic utilities for writing tests, by Michael
61947107 840Schwern. See L<Test::Simple>.
77c8cf41
JH
841
842=item *
843
61947107
JH
844C<Text::Balanced> has been added, for extracting delimited text
845sequences from strings, from Damian Conway.
77c8cf41
JH
846
847 use Text::Balanced 'extract_delimited';
848
849 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
850
851$a will be "'never say never'", $b will be ', he never said'.
852
853In addition to extract_delimited() there are also extract_bracketed(),
854extract_quotelike(), extract_codeblock(), extract_variable(),
855extract_tagged(), extract_multiple(), gen_delimited_pat(), and
856gen_extract_tagged(). With these you can implement rather advanced
61947107 857parsing algorithms. See L<Text::Balanced>.
77c8cf41
JH
858
859=item *
860
c2e23569 861C<threads> is an interface to interpreter threads, by Arthur Bergman.
61947107 862Interpreter threads (ithreads) is the new thread model introduced in
c2e23569
JH
863Perl 5.6 but only available as an internal interface for extension
864writers (and for Win32 Perl for C<fork()> emulation). See L<threads>.
77c8cf41
JH
865
866=item *
867
61947107
JH
868C<threads::shared> allows data sharing for interpreter threads, from
869Arthur Bergman. In the ithreads model any data sharing between
870threads must be explicit, as opposed to the old 5.005 thread model
871where data sharing was implicit. See L<threads::shared>.
77c8cf41
JH
872
873=item *
874
1f089b22
JH
875C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
876lines of a file.
b3b08c80
JH
877
878=item *
879
79f69e33
JH
880C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
881
882=item *
883
61947107 884C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
ba370e9b
JH
885references (unlike the standard Tie::RefHash) The module is contained
886within Tie::RefHash, see L<Tie::RefHash>.
77c8cf41
JH
887
888=item *
889
61947107
JH
890C<Time::HiRes> provides high resolution timing (ualarm, usleep,
891and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
77c8cf41
JH
892
893=item *
894
61947107
JH
895C<Unicode::UCD> offers a querying interface to the Unicode Character
896Database. See L<Unicode::UCD>.
77c8cf41
JH
897
898=item *
899
61947107
JH
900C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
901for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
77c8cf41
JH
902
903=item *
904
61947107
JH
905C<Unicode::Normalize> implements the various Unicode normalization
906forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
77c8cf41
JH
907
908=item *
909
61947107
JH
910C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
911typemaps. Nothing gets installed but for extension writers the code
912is worth studying.
77c8cf41
JH
913
914=back
915
916=head2 Updated And Improved Modules and Pragmata
917
918=over 4
919
920=item *
921
61947107
JH
922The following independently supported modules have been updated to the
923newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
924Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
925(Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable,
926Term::ANSIColor, Test, Text-Tabs+Wrap.
77c8cf41
JH
927
928=item *
929
61947107 930The attributes::reftype() now works on tied arguments.
77c8cf41
JH
931
932=item *
933
057b7f2b 934AutoLoader can now be disabled with C<no AutoLoader;>.
77c8cf41
JH
935
936=item *
937
1e13d81f
JH
938B::Deparse has been significantly enhanced. It now can deparse almost
939all of the standard test suite (so that the tests still succeed).
940There is a make target "test.deparse" for trying this out.
77c8cf41
JH
941
942=item *
943
1e13d81f 944Class::Struct can now define the classes in compile time.
77c8cf41
JH
945
946=item *
947
1e13d81f
JH
948Class::Struct now assigns the array/hash element if the accessor
949is called with an array/hash element as the B<sole> argument.
77c8cf41
JH
950
951=item *
952
1e13d81f 953Data::Dumper has now an option to sort hashes.
77c8cf41
JH
954
955=item *
956
1e13d81f
JH
957Data::Dumper has now an option to dump code references
958using B::Deparse.
77c8cf41
JH
959
960=item *
961
44da0e71
JH
962DB_File now supports newer Berkeley DB versions, among
963other improvements.
964
965=item *
966
1e13d81f
JH
967The English module can now be used without the infamous performance
968hit by saying
77c8cf41 969
66023b77 970 use English '-no_match_vars';
77c8cf41 971
1e13d81f
JH
972(Assuming, of course, that one doesn't need the troublesome variables
973C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
974C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
77c8cf41
JH
975
976=item *
977
1e13d81f
JH
978Fcntl, Socket, and Sys::Syslog have been rewritten to use the
979new-style constant dispatch section (see L<ExtUtils::Constant>).
980This means that they will be more robust and hopefully faster.
77c8cf41
JH
981
982=item *
983
44da0e71
JH
984File::Find now chdir()s correctly when chasing symbolic links.
985
986=item *
987
1e13d81f
JH
988File::Find now has pre- and post-processing callbacks. It also
989correctly changes directories when chasing symbolic links. Callbacks
990(naughtily) exiting with "next;" instead of "return;" now work.
61947107
JH
991
992=item *
993
1e13d81f
JH
994File::Find is now (again) reentrant. It also has been made
995more portable.
77c8cf41 996
61947107
JH
997=item *
998
1e13d81f
JH
999File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1000prototype mismatch with CORE::glob().
61947107
JH
1001
1002=item *
1003
1004File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
1005the returned list of filenames.
77c8cf41
JH
1006
1007=item *
1008
1009Devel::Peek now has an interface for the Perl memory statistics
1010(this works only if you are using perl's malloc, and if you have
1011compiled with debugging).
1012
1013=item *
1014
1e13d81f
JH
1015IPC::Open3 now allows the use of numeric file descriptors.
1016
1017=item *
1018
77c8cf41
JH
1019IO::Socket has now atmark() method, which returns true if the socket
1020is positioned at the out-of-band mark. The method is also exportable
1021as a sockatmark() function.
1022
1023=item *
1024
1025IO::Socket::INET has support for ReusePort option (if your platform
1026supports it). The Reuse option now has an alias, ReuseAddr. For clarity
1027you may want to prefer ReuseAddr.
1028
1029=item *
1030
61947107
JH
1031IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
1032that the operating system will make one up.)
77c8cf41
JH
1033
1034=item *
1035
1e13d81f
JH
1036use lib now works identically to @INC. Removing directories
1037with 'no lib' now works.
1038
1039=item *
1040
58175c9b
JH
1041ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
1042leads into better portability.
1043
1044=item *
1045
1e13d81f
JH
1046Math::BigFloat and Math::BigInt have undergone a full rewrite.
1047They are now magnitudes faster, and they support various
61947107 1048bignum libraries such as GMP and PARI as their backends.
f39f21d8
JH
1049
1050=item *
1051
44da0e71
JH
1052Math::Complex handles inf, NaN etc., better.
1053
1054=item *
1055
58175c9b
JH
1056Net::Ping has been muchly enhanced. Multihoming is now supported.
1057There is now "external" protocol which uses Net::Ping::External module
1058which runs external ping(1) and parses the output. A version of
1059Net::Ping::External is available in CPAN.
f39f21d8 1060
77c8cf41 1061=item *
f39f21d8 1062
da6838c8 1063POSIX::sigaction() is now much more flexible and robust.
61947107
JH
1064You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
1065handlers, installing new handlers was not atomic.
f39f21d8
JH
1066
1067=item *
1068
da6838c8 1069In Safe the C<%INC> now localised in a Safe compartment so that
76663d67
JH
1070use/require work.
1071
1072=item *
1073
44da0e71
JH
1074In SDBM_File on dosish platforms, some keys went missing because of
1075lack of support for files with "holes". A workaround for the problem
1076has been added.
1077
1078=item *
1079
da6838c8 1080In Search::Dict one can now have a pre-processing hook for the
76663d67 1081lines being searched.
1e13d81f
JH
1082
1083=item *
1084
1085The Shell module now has an OO interface.
1086
1087=item *
1088
61947107 1089The Test module has been significantly enhanced.
f39f21d8
JH
1090
1091=item *
1092
da6838c8 1093The vars pragma now supports declaring fully qualified variables.
77c8cf41 1094(Something that C<our()> does not and will not support.)
f39f21d8 1095
888aee59
JH
1096=item *
1097
58175c9b 1098The C<utf8::> name space (as in the pragma) provides various
61947107
JH
1099Perl-callable functions to provide low level access to Perl's
1100internal Unicode representation. At the moment only length()
1101has been implemented.
888aee59 1102
f39f21d8
JH
1103=back
1104
77c8cf41 1105=head1 Utility Changes
f39f21d8
JH
1106
1107=over 4
1108
1109=item *
1110
61947107 1111Emacs perl mode (emacs/cperl-mode.el) has been updated to version
77c8cf41 11124.31.
f39f21d8
JH
1113
1114=item *
1115
61947107 1116F<emacs/e2ctags.pl> is now much faster.
f39f21d8
JH
1117
1118=item *
1119
1e13d81f
JH
1120C<h2ph> now supports C trigraphs.
1121
1122=item *
1123
1124C<h2xs> now produces a template README.
f39f21d8 1125
77c8cf41
JH
1126=item *
1127
1e13d81f
JH
1128C<h2xs> now uses C<Devel::PPort> for better portability between
1129different versions of Perl.
f39f21d8
JH
1130
1131=item *
1132
1e13d81f 1133C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
61947107
JH
1134newly created extensions that define constants. Since the new code is
1135more correct (if you have two constants where the first one is a
1136prefix of the second one, the first constant B<never> gets defined),
1137less lossy (it uses integers for integer constant, as opposed to the
1138old code that used floating point numbers even for integer constants),
1139and slightly faster, you might want to consider regenerating your
1140extension code (the new scheme makes regenerating easy).
1141L<h2xs> now also supports C trigraphs.
f39f21d8
JH
1142
1143=item *
1144
1e13d81f 1145C<libnetcfg> has been added to configure the libnet.
f39f21d8
JH
1146
1147=item *
1148
1e13d81f 1149C<perlbug> is now much more robust. It also sends the bug report to
61947107 1150perl.org, not perl.com.
f39f21d8
JH
1151
1152=item *
1153
1e13d81f 1154C<perlcc> has been rewritten and its user interface (that is,
61947107 1155command line) is much more like that of the UNIX C compiler, cc.
44da0e71 1156(The perlbc tools has been removed. Use C<perlcc -B> instead.)
f39f21d8
JH
1157
1158=item *
1159
aecce728
JH
1160C<perlivp> is a new Installation Verification Procedure utility
1161for running any time after installing Perl.
f39f21d8
JH
1162
1163=item *
1164
1e13d81f 1165C<pod2html> now allows specifying a cache directory.
f39f21d8
JH
1166
1167=item *
1168
1e13d81f
JH
1169C<s2p> has been completely rewritten in Perl. (It is in fact a full
1170implementation of sed in Perl: you can use the sed functionality by
1171using the C<psed> utility.)
61947107
JH
1172
1173=item *
1174
1e13d81f 1175C<xsubpp> now understands POD documentation embedded in the *.xs files.
f39f21d8
JH
1176
1177=item *
1178
1e13d81f 1179C<xsubpp> now supports OUT keyword.
f39f21d8
JH
1180
1181=back
1182
77c8cf41 1183=head1 New Documentation
f39f21d8
JH
1184
1185=over 4
1186
1187=item *
1188
77c8cf41
JH
1189perl56delta details the changes between the 5.005 release and the
11905.6.0 release.
f39f21d8
JH
1191
1192=item *
1193
61947107
JH
1194perlclib documents the internal replacements for standard C library
1195functions. (Interesting only for extension writers and Perl core
1196hackers.)
1197
1198=item *
1199
77c8cf41 1200perldebtut is a Perl debugging tutorial.
f39f21d8 1201
77c8cf41 1202=item *
f39f21d8 1203
77c8cf41 1204perlebcdic contains considerations for running Perl on EBCDIC platforms.
f39f21d8 1205
77c8cf41
JH
1206=item *
1207
888aee59
JH
1208perlintro is a gentle introduction to Perl.
1209
1210=item *
1211
61947107
JH
1212perliol documents the internals of PerlIO with layers.
1213
1214=item *
1215
888aee59
JH
1216perlmodstyle is a style guide for writing modules.
1217
1218=item *
1219
77c8cf41 1220perlnewmod tells about writing and submitting a new module.
f39f21d8
JH
1221
1222=item *
1223
34babc16
JH
1224perlpacktut is a pack() tutorial.
1225
1226=item *
1227
888aee59
JH
1228perlpod has been rewritten to be clearer and to record the best
1229practices gathered over the years.
1230
1231=item *
1232
057b7f2b 1233perlpodspec is a more formal specification of the pod format,
888aee59
JH
1234mainly of interest for writers of pod applications, not to
1235people writing in pod.
1236
1237=item *
1238
77c8cf41 1239perlretut is a regular expression tutorial.
f39f21d8
JH
1240
1241=item *
1242
77c8cf41
JH
1243perlrequick is a regular expressions quick-start guide.
1244Yes, much quicker than perlretut.
f39f21d8 1245
77c8cf41 1246=item *
f39f21d8 1247
61947107
JH
1248perltodo has been updated.
1249
1250=item *
1251
888aee59 1252perltootc has been renamed as perltooc (to not to conflict
61947107 1253with perltoot in filesystems restricted to "8.3" names)
888aee59
JH
1254
1255=item *
1256
58175c9b
JH
1257perluniintro is an introduction to using Unicode in Perl.
1258(perlunicode is more of a detailed reference and background
1259information)
888aee59
JH
1260
1261=item *
1262
77c8cf41
JH
1263perlutil explains the command line utilities packaged with the Perl
1264distribution.
1265
1266=back
f39f21d8 1267
61947107
JH
1268The following platform-specific documents are available before
1269the installation as README.I<platform>, and after the installation
1270as perlI<platform>:
f39f21d8 1271
61947107
JH
1272 perlaix perlamiga perlapollo perlbeos perlbs2000
1273 perlce perlcygwin perldgux perldos perlepoc perlhpux
1274 perlhurd perlmachten perlmacos perlmint perlmpeix
1275 perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
1276 perltru64 perluts perlvmesa perlvms perlvos perlwin32
77c8cf41
JH
1277
1278=over 4
1279
1280=item *
1281
61947107
JH
1282The documentation for the POSIX-BC platform is called "BS2000", to avoid
1283confusion with the Perl POSIX module.
77c8cf41
JH
1284
1285=item *
1286
61947107
JH
1287The documentation for the WinCE platform is called "CE", to avoid
1288confusion with the perlwin32 documentation on 8.3-restricted filesystems.
77c8cf41
JH
1289
1290=back
1291
1292=head1 Performance Enhancements
1293
1294=over 4
1295
1296=item *
1297
44da0e71
JH
1298map() could get pathologically slow when the result list it generates
1299is larger than the source list. The performance has been improved for
1300common scenarios.
77c8cf41
JH
1301
1302=item *
1303
e1f170bd
JH
1304sort() has been changed to use primarily mergesort internally as
1305opposed to the earlier quicksort. For very small lists this may
1306result in slightly slower sorting times, but in general the speedup
1307should be at least 20%. Additional bonuses are that the worst case
1308behaviour of sort() is now better (in computer science terms it now
1309runs in time O(N log N), as opposed to quicksort's Theta(N**2)
1310worst-case run time behaviour), and that sort() is now stable
1311(meaning that elements with identical keys will stay ordered as they
1312were before the sort). See the C<sort> pragma for information.
77c8cf41 1313
05e25c75
JH
1314The story in more detail: suppose you want to serve yourself a little
1315slice of Pi.
1316
1317 @digits = ( 3,1,4,1,5,9 );
1318
1319A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
1320Which C<1> comes first is hard to know, since one C<1> looks pretty
1321much like any other. You can regard this as totally trivial,
1322or somewhat profound. However, if you just want to sort the even
1323digits ahead of the odd ones, then what will
1324
1325 sort { ($a % 2) <=> ($b % 2) } @digits;
1326
1327yield? The only even digit, C<4>, will come first. But how about
1328the odd numbers, which all compare equal? With the quicksort algorithm
1329used to implement Perl 5.6 and earlier, the order of ties is left up
1330to the sort. So, as you add more and more digits of Pi, the order
1331in which the sorted even and odd digits appear will change.
1332and, for sufficiently large slices of Pi, the quicksort algorithm
1333in Perl 5.8 won't return the same results even if reinvoked with the
1334same input. The justification for this rests with quicksort's
1335worst case behavior. If you run
1336
1337 sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
1338
1339(something you might approximate if you wanted to merge two sorted
1340arrays using sort), doubling $N doesn't just double the quicksort time,
1341it I<quadruples> it. Quicksort has a worst case run time that can
1342grow like N**2, so-called I<quadratic> behaviour, and it can happen
1343on patterns that may well arise in normal use. You won't notice this
1344for small arrays, but you I<will> notice it with larger arrays,
1345and you may not live long enough for the sort to complete on arrays
1346of a million elements. So the 5.8 quicksort scrambles large arrays
1347before sorting them, as a statistical defence against quadratic behaviour.
1348But that means if you sort the same large array twice, ties may be
1349broken in different ways.
1350
1351Because of the unpredictability of tie-breaking order, and the quadratic
1352worst-case behaviour, quicksort was I<almost> replaced completely with
1353a stable mergesort. I<Stable> means that ties are broken to preserve
1354the original order of appearance in the input array. So
1355
1356 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
1357
1358will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
1359appear in the output in the same order they appeared in the input.
1360Mergesort has worst case O(NlogN) behaviour, the best value
1361attainable. And, ironically, this mergesort does particularly
1362well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
1363in O(N) time. But quicksort was rescued at the last moment because
1364it is faster than mergesort on certain inputs and platforms.
1365For example, if you really I<don't> care about the order of even
1366and odd digits, quicksort will run in O(N) time; it's very good
1367at sorting many repetitions of a small number of distinct elements.
1368The quicksort divide and conquer strategy works well on platforms
1369with relatively small, very fast, caches. Eventually, the problem gets
1370whittled down to one that fits in the cache, from which point it
1371benefits from the increased memory speed.
1372
1373Quicksort was rescued by implementing a sort pragma to control aspects
1374of the sort. The B<stable> subpragma forces stable behaviour,
1375regardless of algorithm. The B<_quicksort> and B<_mergesort>
1376subpragmas are heavy-handed ways to select the underlying implementation.
1377The leading C<_> is a reminder that these subpragmas may not survive
1378beyond 5.8. More appropriate mechanisms for selecting the implementation
1379exist, but they wouldn't have arrived in time to save quicksort.
1380
77c8cf41
JH
1381=item *
1382
1383Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1384(http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1385reasonably fast while producing a much better spread of values than
1386the old hashing algorithm (originally by Chris Torek, later tweaked by
1387Ilya Zakharevich). Hash values output from the algorithm on a hash of
1388all 3-char printable ASCII keys comes much closer to passing the
1389DIEHARD random number generation tests. According to perlbench, this
1390change has not affected the overall speed of Perl.
1391
1392=item *
1393
1394unshift() should now be noticeably faster.
1395
1396=back
1397
1398=head1 Installation and Configuration Improvements
1399
1400=head2 Generic Improvements
1401
1402=over 4
1403
1404=item *
1405
1406INSTALL now explains how you can configure Perl to use 64-bit
1407integers even on non-64-bit platforms.
1408
1409=item *
1410
1411Policy.sh policy change: if you are reusing a Policy.sh file
1412(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1413Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1414them will now be changed to the new prefix, /foo/bar. (Previously
1415only $prefix changed.) If you do not like this new behaviour,
1416specify prefix, siteprefix, and vendorprefix explicitly.
1417
1418=item *
1419
1420A new optional location for Perl libraries, otherlibdirs, is available.
1421It can be used for example for vendor add-ons without disturbing Perl's
1422own library directories.
1423
1424=item *
1425
1426In many platforms the vendor-supplied 'cc' is too stripped-down to
1427build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1428to be the case and 'cc' does not seem to be the GNU C compiler
1429'gcc', an automatic attempt is made to find and use 'gcc' instead.
1430
1431=item *
1432
1433gcc needs to closely track the operating system release to avoid
1434build problems. If Configure finds that gcc was built for a different
1435operating system release than is running, it now gives a clearly visible
1436warning that there may be trouble ahead.
1437
1438=item *
1439
1440If binary compatibility with the 5.005 release is not wanted, Configure
1441no longer suggests including the 5.005 modules in @INC.
1442
1443=item *
1444
1445Configure C<-S> can now run non-interactively.
1446
1447=item *
1448
44da0e71
JH
1449Configure support for pdp11-style memory models has been removed due
1450to obsolescence.
1451
1452=item *
1453
77c8cf41 1454configure.gnu now works with options with whitespace in them.
f39f21d8 1455
77c8cf41 1456=item *
f39f21d8 1457
77c8cf41 1458installperl now outputs everything to STDERR.
f39f21d8 1459
77c8cf41
JH
1460=item *
1461
1462$Config{byteorder} is now computed dynamically (this is more robust
1463with "fat binaries" where an executable image contains binaries for
1464more than one binary platform.)
f39f21d8
JH
1465
1466=item *
1467
1468Because PerlIO is now the default on most platforms, "-perlio" doesn't
1469get appended to the $Config{archname} (also known as $^O) anymore.
1470Instead, if you explicitly choose not to use perlio (Configure command
1471line option -Uuseperlio), you will get "-stdio" appended.
1472
1473=item *
1474
1475Another change related to the architecture name is that "-64all"
1476(-Duse64bitall, or "maximally 64-bit") is appended only if your
1477pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1478
1479=item *
1480
77c8cf41
JH
1481In AFS installations one can configure the root of the AFS to be
1482somewhere else than the default F</afs> by using the Configure
1483parameter C<-Dafsroot=/some/where/else>.
1484
1485=item *
1486
61947107
JH
1487APPLLIB_EXP, a less-know configuration-time definition, has been
1488documented. It can be used to prepend site-specific directories
1489to Perl's default search path (@INC), see INSTALL for information.
1490
1491=item *
1492
77c8cf41
JH
1493The version of Berkeley DB used when the Perl (and, presumably, the
1494DB_File extension) was built is now available as
1495C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1496from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1497DB_VERSION_PATCH_CFG> from C.
1498
1499=item *
1500
61947107
JH
1501Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1502has been documented in INSTALL.
77c8cf41
JH
1503
1504=item *
1505
61947107
JH
1506If you have CPAN access (either network or a local copy such as a
1507CD-ROM) you can during specify extra modules to Configure to build and
1508install with Perl using the -Dextras=... option. See INSTALL for
1509more details.
f39f21d8 1510
61947107 1511=item *
f39f21d8 1512
61947107
JH
1513In addition to config.over a new override file, config.arch, is
1514available. That is supposed to be used by hints file writers for
1515architecture-wide changes (as opposed to config.over which is for
1516site-wide changes).
f39f21d8
JH
1517
1518=item *
1519
e1f170bd
JH
1520If your file system supports symbolic links you can build Perl outside
1521of the source directory by
1522
1523 mkdir /tmp/perl/build/directory
1524 cd /tmp/perl/build/directory
1525 sh /path/to/perl/source/Configure -Dmksymlinks ...
1526
1527This will create in /tmp/perl/build/directory a tree of symbolic links
1528pointing to files in /path/to/perl/source. The original files are left
1529unaffected. After Configure has finished you can just say
1530
1531 make all test
1532
1533and Perl will be built and tested, all in /tmp/perl/build/directory.
1534
1535=item *
1536
61947107
JH
1537For Perl developers several new make targets for profiling
1538and debugging have been added, see L<perlhack>.
1539
1540=over 8
f39f21d8
JH
1541
1542=item *
1543
61947107
JH
1544Use of the F<gprof> tool to profile Perl has been documented in
1545L<perlhack>. There is a make target called "perl.gprof" for
1546generating a gprofiled Perl executable.
f39f21d8
JH
1547
1548=item *
1549
61947107
JH
1550If you have GCC 3, there is a make target called "perl.gcov" for
1551creating a gcoved Perl executable for coverage analysis. See
1552L<perlhack>.
f39f21d8
JH
1553
1554=item *
1555
61947107
JH
1556If you are on IRIX or Tru64 platforms, new profiling/debugging options
1557have been added, see L<perlhack> for more information about pixie and
1558Third Degree.
1559
1560=back
f39f21d8
JH
1561
1562=item *
1563
61947107
JH
1564Guidelines of how to construct minimal Perl installations have
1565been added to INSTALL.
f39f21d8
JH
1566
1567=item *
1568
61947107
JH
1569The Thread extension is now not built at all under ithreads
1570(C<Configure -Duseithreads>) because it wouldn't work anyway (the
1571Thread extension requires being Configured with C<-Duse5005threads>).
f39f21d8 1572
61947107
JH
1573But note that the Thread.pm interface is now shared by both
1574thread models.
f39f21d8 1575
61947107 1576=back
f39f21d8 1577
61947107 1578=head2 New Or Improved Platforms
f39f21d8 1579
61947107
JH
1580For the list of platforms known to support Perl,
1581see L<perlport/"Supported Platforms">.
1582
1583=over 4
f39f21d8
JH
1584
1585=item *
1586
61947107 1587AIX dynamic loading should be now better supported.
f39f21d8 1588
f39f21d8
JH
1589=item *
1590
77c8cf41
JH
1591AIX should now work better with gcc, threads, and 64-bitness. Also the
1592long doubles support in AIX should be better now. See L<perlaix>.
f39f21d8
JH
1593
1594=item *
1595
61947107
JH
1596After a long pause, AmigaOS has been verified to be happy with Perl.
1597
1598=item *
1599
77c8cf41 1600AtheOS (http://www.atheos.cx/) is a new platform.
f39f21d8 1601
77c8cf41 1602=item *
f39f21d8 1603
58175c9b
JH
1604BeOS has been reclaimed.
1605
1606=item *
1607
77c8cf41 1608DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
f39f21d8
JH
1609
1610=item *
1611
77c8cf41 1612DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
f39f21d8
JH
1613
1614=item *
1615
61947107
JH
1616EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1617have been regained. Many test suite tests still fail and the
1618co-existence of Unicode and EBCDIC isn't quite settled, but the
1619situation is much better than with Perl 5.6. See L<perlos390>,
1620L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
f39f21d8
JH
1621
1622=item *
1623
61947107
JH
1624Building perl with -Duseithreads or -Duse5005threads now works under
1625HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1626need a thread library package installed. See README.hpux.
f39f21d8 1627
77c8cf41 1628=item *
f39f21d8 1629
61947107
JH
1630MacOS Classic (MacPerl has of course been available since
1631perl 5.004 but now the source code bases of standard Perl
1632and MacPerl have been synchronised)
f39f21d8 1633
77c8cf41 1634=item *
f39f21d8 1635
61947107
JH
1636MacOS X (or Darwin) should now be able to build Perl even on HFS+
1637filesystems. (The case-insensitivity confused the Perl build process.)
f39f21d8 1638
888aee59
JH
1639=item *
1640
61947107 1641NCR MP-RAS is now supported.
888aee59
JH
1642
1643=item *
1644
58175c9b
JH
1645All the NetBSD specific patches (except for the installation
1646specific ones) have been merged back to the main distribution.
1647
1648=item *
1649
61947107 1650NetWare from Novell is now supported. See L<perlnetware>.
888aee59
JH
1651
1652=item *
1653
61947107 1654NonStop-UX is now supported.
888aee59
JH
1655
1656=item *
1657
44da0e71
JH
1658NEC SUPER-UX is now supported.
1659
1660=item *
1661
58175c9b
JH
1662All the OpenBSD specific patches (except for the installation
1663specific ones) have been merged back to the main distribution.
1664
1665=item *
1666
1667Perl has been tested with the GNU pth userlevel thread package
1668( http://www.gnu.org/software/pth/pth.html ) . All but one thread
1669test worked, and that one failure was because of test results arriving
1670in unexpected order.
1671
1672=item *
1673
61947107 1674Amdahl UTS UNIX mainframe platform is now supported.
888aee59
JH
1675
1676=item *
1677
61947107
JH
1678WinCE is now supported. See L<perlce>.
1679
1680=item *
1681
1682z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1683support for dynamic loading. This is not selected by default,
1684however, you must specify -Dusedl in the arguments of Configure.
888aee59 1685
f39f21d8
JH
1686=back
1687
1688=head1 Selected Bug Fixes
1689
e1f170bd
JH
1690Numerous memory leaks and uninitialized memory accesses have been
1691hunted down. Most importantly anonymous subs used to leak quite
1692a bit.
ba370e9b 1693
f39f21d8
JH
1694=over 4
1695
1696=item *
1697
e1f170bd 1698The autouse pragma didn't work for Multi::Part::Function::Names.
f39f21d8
JH
1699
1700=item *
1701
44da0e71
JH
1702caller() could cause core dumps in certain situations. Carp was sometimes
1703affected by this problem.
1704
1705=item *
1706
e1f170bd
JH
1707chop(@list) in list context returned the characters chopped in
1708reverse order. This has been reversed to be in the right order.
f39f21d8
JH
1709
1710=item *
1711
e1f170bd
JH
1712Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1713when building the Perl binary. The only exception to this is SunOS 4.x,
1714which needs them.
f39f21d8
JH
1715
1716=item *
1717
e1f170bd
JH
1718The behaviour of non-decimal but numeric string constants such as
1719"0x23" was platform-dependent: in some platforms that was seen as 35,
1720in some as 0, in some as a floating point number (don't ask). This
1721was caused by Perl using the operating system libraries in a situation
1722where the result of the string to number conversion is undefined: now
1723Perl consistently handles such strings as zero in numeric contexts.
f39f21d8
JH
1724
1725=item *
1726
e1f170bd 1727The order of DESTROYs has been made more predictable.
f39f21d8
JH
1728
1729=item *
1730
e1f170bd
JH
1731Several debugger fixes: exit code now reflects the script exit code,
1732condition C<"0"> now treated correctly, the C<d> command now checks
44da0e71
JH
1733line number, the C<$.> no longer gets corrupted, all debugger output
1734now goes correctly to the socket if RemotePort is set.
1735
1736=item *
1737
1738Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
1739when statically building extensions into perl. This has been corrected.
f39f21d8
JH
1740
1741=item *
1742
e1f170bd 1743L<dprofpp> -R didn't work.
f39f21d8
JH
1744
1745=item *
1746
e1f170bd 1747C<*foo{FORMAT}> now works.
44da0e71
JH
1748=item *
1749
1750Infinity is now recognized as a number.
f39f21d8
JH
1751
1752=item *
1753
e1f170bd
JH
1754UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1755the Tk extension with 5.6.0.)
f39f21d8
JH
1756
1757=item *
1758
e1f170bd
JH
1759Lexicals I: lexicals outside an eval "" weren't resolved
1760correctly inside a subroutine definition inside the eval "" if they
1761were not already referenced in the top level of the eval""ed code.
f39f21d8
JH
1762
1763=item *
1764
e1f170bd
JH
1765Lexicals II: lexicals leaked at file scope into subroutines that
1766were declared before the lexicals.
f39f21d8
JH
1767
1768=item *
1769
44da0e71
JH
1770Lexical warnings now propagating correctly between scopes
1771and into C<eval "...">.
1772
1773=item *
1774
1775C<use warnings qw(FATAL all)> did not work as intended. This has been
1776corrected.
1777
1778=item *
1779
1780warnings::enabled() now reports the state of $^W correctly if the caller
1781isn't using lexical warnings.
f39f21d8
JH
1782
1783=item *
1784
e1f170bd 1785Line renumbering with eval and C<#line> now works.
f39f21d8
JH
1786
1787=item *
1788
e1f170bd 1789Fixed numerous memory leaks, especially in eval "".
f39f21d8
JH
1790
1791=item *
1792
e1f170bd
JH
1793mkdir() now ignores trailing slashes in the directory name,
1794as mandated by POSIX.
f39f21d8
JH
1795
1796=item *
1797
e1f170bd
JH
1798Some versions of glibc have a broken modfl(). This affects builds
1799with C<-Duselongdouble>. This version of Perl detects this brokenness
1800and has a workaround for it. The glibc release 2.2.2 is known to have
1801fixed the modfl() bug.
f39f21d8
JH
1802
1803=item *
1804
e1f170bd
JH
1805Modulus of unsigned numbers now works (4063328477 % 65535 used to
1806return 27406, instead of 27047).
f39f21d8
JH
1807
1808=item *
1809
e1f170bd
JH
1810Some "not a number" warnings introduced in 5.6.0 eliminated to be
1811more compatible with 5.005. Infinity is now recognised as a number.
f39f21d8 1812
77c8cf41 1813=item *
f39f21d8 1814
44da0e71
JH
1815Numeric conversions did not recognize changes in the string value
1816properly in certain circumstances.
1817
1818=item *
1819
e1f170bd 1820Attributes (like :shared) didn't work with our().
f39f21d8
JH
1821
1822=item *
1823
e1f170bd 1824our() variables will not cause "will not stay shared" warnings.
f39f21d8
JH
1825
1826=item *
1827
44da0e71
JH
1828"our" variables of the same name declared in two sibling blocks
1829resulted in bogus warnings about "redeclaration" of the variables.
1830The problem has been corrected.
1831
1832=item *
1833
e1f170bd 1834pack "Z" now correctly terminates the string with "\0".
f39f21d8
JH
1835
1836=item *
1837
e1f170bd
JH
1838Fix password routines which in some shadow password platforms
1839(e.g. HP-UX) caused getpwent() to return every other entry.
f39f21d8 1840
77c8cf41 1841=item *
f39f21d8 1842
e1f170bd
JH
1843The PERL5OPT environment variable (for passing command line arguments
1844to Perl) didn't work for more than a single group of options.
f39f21d8 1845
77c8cf41 1846=item *
f39f21d8 1847
e1f170bd 1848PERL5OPT with embedded spaces didn't work.
f39f21d8 1849
77c8cf41 1850=item *
f39f21d8 1851
e1f170bd 1852printf() no longer resets the numeric locale to "C".
f39f21d8 1853
77c8cf41 1854=item *
f39f21d8 1855
44da0e71
JH
1856C<qw(a\\b)> now parses correctly as C<'a\\b'>.
1857
1858=item *
1859
1860pos() did not return the correct value within s///ge in earlier
1861versions. This is now handled correctly.
f39f21d8 1862
77c8cf41 1863=item *
f39f21d8 1864
e1f170bd
JH
1865Printing quads (64-bit integers) with printf/sprintf now works
1866without the q L ll prefixes (assuming you are on a quad-capable platform).
f39f21d8 1867
77c8cf41 1868=item *
f39f21d8 1869
e1f170bd 1870Regular expressions on references and overloaded scalars now work.
f39f21d8 1871
ba370e9b
JH
1872=item *
1873
e1f170bd
JH
1874Right-hand side magic (GMAGIC) could in many cases such as string
1875concatenation be invoked too many times.
ba370e9b
JH
1876
1877=item *
1878
e1f170bd 1879scalar() now forces scalar context even when used in void context.
ba370e9b
JH
1880
1881=item *
1882
e1f170bd 1883SOCKS support is now much more robust.
ba370e9b
JH
1884
1885=item *
1886
e1f170bd
JH
1887sort() arguments are now compiled in the right wantarray context
1888(they were accidentally using the context of the sort() itself).
44da0e71
JH
1889The comparison block is now run in scalar context, and the arguments
1890to be sorted are always provided list context.
ba370e9b
JH
1891
1892=item *
1893
e1f170bd 1894Changed the POSIX character class C<[[:space:]]> to include the (very
c2e23569
JH
1895rarely used) vertical tab character. Added a new POSIX-ish character
1896class C<[[:blank:]]> which stands for horizontal whitespace
1897(currently, the space and the tab).
ba370e9b
JH
1898
1899=item *
1900
1901The tainting behaviour of sprintf() has been rationalized. It does
1902not taint the result of floating point formats anymore, making the
1903behaviour consistent with that of string interpolation.
1904
1905=item *
1906
44da0e71
JH
1907Some cases of inconsistent taint propagation (such as within hash
1908values) have been fixed.
1909
1910=item *
1911
1912The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
1913of simple pattern matches. These are now handled better.
1914
1915=item *
1916
1917Regular expression debug output (whether through C<use re 'debug'>
1918or via C<-Dr>) now looks better.
1919
1920=item *
1921
1922Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
1923bug has been fixed.
1924
1925=item *
1926
1927Use of $& could trigger a core dump under some situations. This
1928is now avoided.
1929
1930=item *
1931
c2e23569
JH
1932The regular expression captured submatches ($1, $2, ...) are now
1933more consistently unset if the match fails, instead of leaving false
1934data lying around in them.
1935
1936=item *
1937
44da0e71
JH
1938readline() on files opened in "slurp" mode could return an extra "" at
1939the end in certain situations. This has been corrected.
1940
1941=item *
1942
1943Autovivification of symbolic references of special variables described
1944in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
1945again now.
1946
1947=item *
1948
da6838c8 1949Sys::Syslog ignored the C<LOG_AUTH> constant.
ba370e9b
JH
1950
1951=item *
1952
e1f170bd 1953All but the first argument of the IO syswrite() method are now optional.
ba370e9b
JH
1954
1955=item *
1956
e1f170bd
JH
1957$AUTOLOAD, sort(), lock(), and spawning subprocesses
1958in multiple threads simultaneously are now thread-safe.
ba370e9b
JH
1959
1960=item *
1961
e1f170bd 1962Tie::ARRAY SPLICE method was broken.
ba370e9b
JH
1963
1964=item *
1965
e1f170bd 1966Allow read-only string on left hand side of non-modifying tr///.
ba370e9b
JH
1967
1968=item *
1969
e1f170bd 1970Several Unicode fixes.
ba370e9b
JH
1971
1972=over 8
1973
1974=item *
1975
e1f170bd
JH
1976BOMs (byte order marks) in the beginning of Perl files
1977(scripts, modules) should now be transparently skipped.
1978UTF-16 (UCS-2) encoded Perl files should now be read correctly.
ba370e9b
JH
1979
1980=item *
1981
e1f170bd 1982The character tables have been updated to Unicode 3.1.1.
ba370e9b
JH
1983
1984=item *
1985
e1f170bd 1986Comparing with utf8 data does not magically upgrade non-utf8 data
58175c9b
JH
1987into utf8. (This was a problem for example if you were mixing data
1988from I/O and Unicode data: your output might have got magically encoded
1989as UTF-8.)
1990
1991=item *
1992
1993Generating illegal Unicode code points like U+FFFE, or the UTF-16
1994surrogates, now also generates an optional warning.
ba370e9b
JH
1995
1996=item *
1997
e1f170bd 1998C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
f39f21d8 1999
77c8cf41 2000=item *
f39f21d8 2001
e1f170bd
JH
2002Concatenation with the C<.> operator or via variable interpolation,
2003C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
2004substitution with C<s///>, single-quoted UTF8, should now work.
f39f21d8 2005
77c8cf41 2006=item *
f39f21d8 2007
e1f170bd
JH
2008The C<tr///> operator now works. Note that the C<tr///CU>
2009functionality has been removed (but see pack('U0', ...)).
f39f21d8 2010
77c8cf41 2011=item *
f39f21d8 2012
e1f170bd 2013C<eval "v200"> now works.
f39f21d8 2014
77c8cf41 2015=item *
f39f21d8 2016
44da0e71
JH
2017Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
2018This has been corrected.
2019
2020=item *
2021
e1f170bd 2022Zero entries were missing from the Unicode classes like C<IsDigit>.
f39f21d8 2023
e1f170bd 2024=back
f39f21d8 2025
44da0e71
JH
2026=item *
2027
2028Large unsigned numbers (those above 2**31) could sometimes lose their
2029unsignedness, causing bogus results in arithmetic operations.
2030
77c8cf41 2031=back
f39f21d8 2032
77c8cf41 2033=head2 Platform Specific Changes and Fixes
f39f21d8
JH
2034
2035=over 4
2036
2037=item *
2038
77c8cf41 2039BSDI 4.*
f39f21d8 2040
77c8cf41 2041Perl now works on post-4.0 BSD/OSes.
f39f21d8
JH
2042
2043=item *
2044
77c8cf41 2045All BSDs
f39f21d8 2046
057b7f2b 2047Setting C<$0> now works (as much as possible; see L<perlvar> for details).
f39f21d8
JH
2048
2049=item *
2050
77c8cf41 2051Cygwin
f39f21d8 2052
77c8cf41 2053Numerous updates; currently synchronised with Cygwin 1.1.4.
f39f21d8
JH
2054
2055=item *
2056
e1f170bd
JH
2057Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2058
2059=item *
2060
77c8cf41 2061EPOC
f39f21d8 2062
77c8cf41 2063EPOC update after Perl 5.6.0. See README.epoc.
f39f21d8
JH
2064
2065=item *
2066
77c8cf41 2067FreeBSD 3.*
f39f21d8 2068
77c8cf41 2069Perl now works on post-3.0 FreeBSDs.
f39f21d8
JH
2070
2071=item *
2072
77c8cf41
JH
2073HP-UX
2074
2075README.hpux updated; C<Configure -Duse64bitall> now almost works.
f39f21d8
JH
2076
2077=item *
2078
77c8cf41 2079IRIX
f39f21d8 2080
77c8cf41
JH
2081Numerous compilation flag and hint enhancements; accidental mixing
2082of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
f39f21d8 2083
77c8cf41 2084=item *
f39f21d8 2085
77c8cf41 2086Linux
f39f21d8 2087
e1f170bd
JH
2088=over 8
2089
2090=item *
2091
77c8cf41 2092Long doubles should now work (see INSTALL).
f39f21d8
JH
2093
2094=item *
2095
e1f170bd
JH
2096Linux previously had problems related to sockaddrlen when using
2097accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
2098
2099=back
2100
2101=item *
2102
77c8cf41 2103MacOS Classic
f39f21d8 2104
77c8cf41
JH
2105Compilation of the standard Perl distribution in MacOS Classic should
2106now work if you have the Metrowerks development environment and
2107the missing Mac-specific toolkit bits. Contact the macperl mailing
2108list for details.
f39f21d8
JH
2109
2110=item *
2111
77c8cf41 2112MPE/iX
f39f21d8 2113
77c8cf41 2114MPE/iX update after Perl 5.6.0. See README.mpeix.
f39f21d8
JH
2115
2116=item *
2117
77c8cf41 2118NetBSD/sparc
f39f21d8 2119
77c8cf41 2120Perl now works on NetBSD/sparc.
f39f21d8
JH
2121
2122=item *
2123
77c8cf41 2124OS/2
f39f21d8 2125
77c8cf41 2126Now works with usethreads (see INSTALL).
f39f21d8
JH
2127
2128=item *
2129
77c8cf41 2130Solaris
f39f21d8 2131
77c8cf41 213264-bitness using the Sun Workshop compiler now works.
f39f21d8
JH
2133
2134=item *
2135
77c8cf41 2136Tru64 (aka Digital UNIX, aka DEC OSF/1)
f39f21d8 2137
77c8cf41
JH
2138The operating system version letter now recorded in $Config{osvers}.
2139Allow compiling with gcc (previously explicitly forbidden). Compiling
2140with gcc still not recommended because buggy code results, even with
2141gcc 2.95.2.
f39f21d8
JH
2142
2143=item *
2144
77c8cf41
JH
2145Unicos
2146
2147Fixed various alignment problems that lead into core dumps either
2148during build or later; no longer dies on math errors at runtime;
2149now using full quad integers (64 bits), previously was using
2150only 46 bit integers for speed.
f39f21d8
JH
2151
2152=item *
2153
77c8cf41
JH
2154VMS
2155
2156chdir() now works better despite a CRT bug; now works with MULTIPLICITY
2157(see INSTALL); now works with Perl's malloc.
f39f21d8 2158
00bb525a
CB
2159The tainting of C<%ENV> elements via C<keys> or C<values> was previously
2160unimplemented. It now works as documented.
2161
2162The C<waitpid> emulation has been improved. The worst bug (now fixed)
2163was that a pid of -1 would cause a wildcard search of all processes on
2164the system. The most significant enhancement is that we can now
2165usually get the completion status of a terminated process.
2166
2167POSIX-style signals are now emulated much better on VMS versions prior
2168to 7.0.
2169
2170The C<system> function and backticks operator have improved
2171functionality and better error handling.
2172
161720b2
CB
2173File access tests now use current process privileges rather than the
2174user's default privileges, which could sometimes result in a mismatch
2175between reported access and actual access.
2176
f39f21d8
JH
2177=item *
2178
77c8cf41 2179Windows
f39f21d8 2180
77c8cf41 2181=over 8
f39f21d8
JH
2182
2183=item *
2184
77c8cf41 2185accept() no longer leaks memory.
f39f21d8
JH
2186
2187=item *
2188
e1f170bd
JH
2189Borland C++ v5.5 is now a supported compiler that can build Perl.
2190However, the generated binaries continue to be incompatible with those
2191generated by the other supported compilers (GCC and Visual C++).
2192
2193=item *
2194
77c8cf41 2195Better chdir() return value for a non-existent directory.
f39f21d8 2196
77c8cf41 2197=item *
f39f21d8 2198
e1f170bd
JH
2199Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2200
2201=item *
2202
77c8cf41 2203New %ENV entries now propagate to subprocesses.
f39f21d8
JH
2204
2205=item *
2206
44da0e71
JH
2207Current directory entries in %ENV are now correctly propagated to child
2208processes.
2209
2210=item *
2211
77c8cf41
JH
2212$ENV{LIB} now used to search for libs under Visual C.
2213
2214=item *
2215
44da0e71
JH
2216fork() emulation has been improved in various ways, but still continues
2217to be experimental. See L<perlfork> for known bugs and caveats.
e1f170bd
JH
2218
2219=item *
2220
77c8cf41 2221A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
f39f21d8
JH
2222
2223=item *
2224
44da0e71
JH
2225Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2226Other bugs in chdir() and Cwd::cwd() have also been fixed.
2227
2228=item *
2229
e1f170bd
JH
2230HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2231
2232=item *
2233
2234The makefiles now provide a single switch to bulk-enable all the features
2235enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
2236
2237=item *
2238
77c8cf41 2239Allow REG_EXPAND_SZ keys in the registry.
f39f21d8
JH
2240
2241=item *
2242
77c8cf41 2243Can now send() from all threads, not just the first one.
f39f21d8
JH
2244
2245=item *
2246
77c8cf41 2247Fake signal handling reenabled, bugs and all.
f39f21d8
JH
2248
2249=item *
2250
44da0e71
JH
2251%SIG has been enabled under USE_ITHREADS, but its use is completely
2252unsupported under all configurations.
2253
2254=item *
2255
77c8cf41
JH
2256Less stack reserved per thread so that more threads can run
2257concurrently. (Still 16M per thread.)
f39f21d8
JH
2258
2259=item *
2260
c2e23569 2261C<File::Spec-&gt;tmpdir()> now prefers C:/temp over /tmp
77c8cf41 2262(works better when perl is running as service).
f39f21d8
JH
2263
2264=item *
2265
77c8cf41 2266Better UNC path handling under ithreads.
f39f21d8
JH
2267
2268=item *
2269
44da0e71
JH
2270wait(), waitpid() and backticks now return the correct exit status under
2271Windows 9x.
f39f21d8
JH
2272
2273=item *
2274
77c8cf41 2275winsock handle leak fixed.
f39f21d8
JH
2276
2277=back
2278
77c8cf41 2279=back
f39f21d8 2280
77c8cf41 2281=head1 New or Changed Diagnostics
f39f21d8 2282
ba370e9b
JH
2283=over 4
2284
2285=item *
2286
12bcd1a6
PM
2287The lexical warnings category "deprecated" is no longer a sub-category
2288of the "syntax" category. It is now a top-level category in its own
2289right.
2290
2291=item *
2292
77c8cf41
JH
2293All regular expression compilation error messages are now hopefully
2294easier to understand both because the error message now comes before
2295the failed regex and because the point of failure is now clearly
ba370e9b
JH
2296marked by a C<E<lt>-- HERE> marker.
2297
2298=item *
f39f21d8 2299
77c8cf41
JH
2300The various "opened only for", "on closed", "never opened" warnings
2301drop the C<main::> prefix for filehandles in the C<main> package,
bea4d472 2302for example C<STDIN> instead of C<main::STDIN>.
f39f21d8 2303
ba370e9b
JH
2304=item *
2305
77c8cf41
JH
2306The "Unrecognized escape" warning has been extended to include C<\8>,
2307C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
f39f21d8 2308
ba370e9b 2309=item *
f39f21d8 2310
77c8cf41
JH
2311Two new debugging options have been added: if you have compiled your
2312Perl with debugging, you can use the -DT and -DR options to trace
2313tokenising and to add reference counts to displaying variables,
2314respectively.
f39f21d8
JH
2315
2316=item *
2317
492652be
RF
2318perl5db.pl has been modified to present a more consistent commands
2319interface, via (CommandSet=580). perl5db.t was also added to test the
2320changes, and as a placeholder for further tests.
2321
2322See L<perldebug>
2323
2324=item *
2325
77c8cf41
JH
2326If an attempt to use a (non-blessed) reference as an array index
2327is made, a warning is given.
f39f21d8
JH
2328
2329=item *
2330
77c8cf41
JH
2331C<push @a;> and C<unshift @a;> (with no values to push or unshift)
2332now give a warning. This may be a problem for generated and evaled
2333code.
f39f21d8 2334
ba370e9b
JH
2335=item *
2336
2337If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2338using the C<"C"> format you will get an optional warning. Similarly
2339for the C<"c"> format and a number less than -128 or more than 127.
2340
2341=item *
2342
2343Certain regex modifiers such as C<(?o)> make sense only if applied to
2344the entire regex. You will an optional warning if you try to do otherwise.
2345
2346=item *
2347
c2e23569
JH
2348Using arrays or hashes as references (e.g. C<< %foo-&gt;{bar} >>
2349has been deprecated for a while. Now you will get an optional warning.
ba370e9b 2350
f39f21d8
JH
2351=back
2352
77c8cf41 2353=head1 Changed Internals
f39f21d8
JH
2354
2355=over 4
2356
2357=item *
2358
77c8cf41
JH
2359perlapi.pod (a companion to perlguts) now attempts to document the
2360internal API.
f39f21d8
JH
2361
2362=item *
2363
77c8cf41
JH
2364You can now build a really minimal perl called microperl.
2365Building microperl does not require even running Configure;
2366C<make -f Makefile.micro> should be enough. Beware: microperl makes
2367many assumptions, some of which may be too bold; the resulting
2368executable may crash or otherwise misbehave in wondrous ways.
2369For careful hackers only.
f39f21d8
JH
2370
2371=item *
2372
c2e23569
JH
2373Added rsignal(), whichsig(), do_join(), op_clear, op_null,
2374ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
2375interfaces to the publicised API. For the full list of the available
2376APIs see L<perlapi>.
f39f21d8
JH
2377
2378=item *
2379
77c8cf41 2380Made possible to propagate customised exceptions via croak()ing.
f39f21d8 2381
77c8cf41 2382=item *
f39f21d8 2383
95f0a2f1
SB
2384Now xsubs can have attributes just like subs. (Well, at least the
2385built-in attributes.)
f39f21d8
JH
2386
2387=item *
2388
77c8cf41
JH
2389dTHR and djSP have been obsoleted; the former removed (because it's
2390a no-op) and the latter replaced with dSP.
f39f21d8
JH
2391
2392=item *
2393
61947107
JH
2394PERL_OBJECT has been completely removed.
2395
2396=item *
2397
ba370e9b
JH
2398The MAGIC constants (e.g. C<'P'>) have been macrofied
2399(e.g. C<PERL_MAGIC_TIED>) for better source code readability
2400and maintainability.
2401
2402=item *
2403
2404The regex compiler now maintains a structure that identifies nodes in
2405the compiled bytecode with the corresponding syntactic features of the
2406original regex expression. The information is attached to the new
2407C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2408complete information.
2409
2410=item *
2411
2412The C code has been made much more C<gcc -Wall> clean. Some warning
2413messages still remain in some platforms, so if you are compiling with
2414gcc you may see some warnings about dubious practices. The warnings
2415are being worked on.
2416
2417=item *
2418
2419F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2420
2421=item *
2422
61947107
JH
2423Documentation on how to use the Perl source repository has been added
2424to F<Porting/repository.pod>.
f39f21d8 2425
888aee59
JH
2426=item *
2427
c2e23569 2428There are now several profiling make targets.
888aee59 2429
77c8cf41 2430=back
f39f21d8 2431
77c8cf41 2432=head1 Security Vulnerability Closed
f39f21d8 2433
77c8cf41 2434(This change was already made in 5.7.0 but bears repeating here.)
f39f21d8 2435
77c8cf41
JH
2436A potential security vulnerability in the optional suidperl component
2437of Perl was identified in August 2000. suidperl is neither built nor
2438installed by default. As of November 2001 the only known vulnerable
2439platform is Linux, most likely all Linux distributions. CERT and
2440various vendors and distributors have been alerted about the vulnerability.
2441See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
2442for more information.
f39f21d8 2443
77c8cf41
JH
2444The problem was caused by Perl trying to report a suspected security
2445exploit attempt using an external program, /bin/mail. On Linux
2446platforms the /bin/mail program had an undocumented feature which
2447when combined with suidperl gave access to a root shell, resulting in
2448a serious compromise instead of reporting the exploit attempt. If you
2449don't have /bin/mail, or if you have 'safe setuid scripts', or if
2450suidperl is not installed, you are safe.
f39f21d8 2451
77c8cf41
JH
2452The exploit attempt reporting feature has been completely removed from
2453Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
2454from all the Perl 5.7 releases), so that particular vulnerability
2455isn't there anymore. However, further security vulnerabilities are,
ba370e9b
JH
2456unfortunately, always possible. The suidperl functionality is most
2457probably going to be removed in Perl 5.10. In any case, suidperl
2458should only be used by security experts who know exactly what they are
2459doing and why they are using suidperl instead of some other solution
2460such as sudo (see http://www.courtesan.com/sudo/).
77c8cf41
JH
2461
2462=head1 New Tests
2463
76663d67
JH
2464Several new tests have been added, especially for the F<lib>
2465subsection. There are now about 34 000 individual tests (spread over
2466about 530 test scripts), in the regression suite (5.6.1 has about
246711700 tests, in 258 test scripts) Many of the new tests are introduced
2468by the new modules, but still in general Perl is now more thoroughly
2469tested.
2470
2471Because of the large number of tests, running the regression suite
2472will take considerably longer time than it used to: expect the suite
2473to take up to 4-5 times longer to run than in perl 5.6. In a really
2474fast machine you can hope to finish the suite in about 5 minutes
2475(wallclock time).
77c8cf41
JH
2476
2477The tests are now reported in a different order than in earlier Perls.
2478(This happens because the test scripts from under t/lib have been moved
2479to be closer to the library/extension they are testing.)
2480
f39f21d8
JH
2481=head1 Known Problems
2482
f39f21d8
JH
2483=head2 AIX
2484
2485=over 4
2486
2487=item *
2488
2489In AIX 4.2 Perl extensions that use C++ functions that use statics
2490may have problems in that the statics are not getting initialized.
2491In newer AIX releases this has been solved by linking Perl with
2492the libC_r library, but unfortunately in AIX 4.2 the said library
2493has an obscure bug where the various functions related to time
2494(such as time() and gettimeofday()) return broken values, and
2495therefore in AIX 4.2 Perl is not linked against the libC_r.
2496
2497=item *
2498
2499vac 5.0.0.0 May Produce Buggy Code For Perl
2500
2501The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2502resulting in few random tests failing, but when the failing tests
2503are run by hand, they succeed. We suggest upgrading to at least
2504vac version 5.0.1.0, that has been known to compile Perl correctly.
2505"lslpp -L|grep vac.C" will tell you the vac version.
2506
2507=back
2508
2509=head2 Amiga Perl Invoking Mystery
2510
2511One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
057b7f2b 2512works, but for example C<bin:perl -v> doesn't. The exact reason isn't
f39f21d8
JH
2513known but the current suspect is the F<ixemul> library.
2514
2515=head2 lib/ftmp-security tests warn 'system possibly insecure'
2516
2517Don't panic. Read INSTALL 'make test' section instead.
2518
2519=head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2520
2521The subtests 11 and 12 sometimes fail and sometimes work.
2522
2523=head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2524
2525The lib/io_multihomed test may hang in HP-UX if Perl has been
2526configured to be 64-bit. Because other 64-bit platforms do not hang in
2527this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2528test attempts to create and connect to "multihomed" sockets (sockets
2529which have multiple IP addresses).
2530
2531=head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2532
2533If perl is configured with -Duse64bitall, the successful result of the
2534subtest 10 of lib/posix may arrive before the successful result of the
2535subtest 9, which confuses the test harness so much that it thinks the
2536subtest 9 failed.
2537
2538=head2 Linux With Sfio Fails op/misc Test 48
2539
2540No known fix.
2541
a0aae13b
JH
2542=head2 Mac OS X
2543
2544The following tests are known to fail:
2545
2546 Failed Test Stat Wstat Total Fail Failed List of Failed
2547 -------------------------------------------------------------------------
2548 ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
2549 ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
2550 ../ext/POSIX/t/posix.t 31 1 3.23% 10
2551 ../lib/warnings.t 450 1 0.22% 316
2552
f39f21d8
JH
2553=head2 OS/390
2554
2555OS/390 has rather many test failures but the situation is actually
2556better than it was in 5.6.0, it's just that so many new modules and
2557tests have been added.
2558
2559 Failed Test Stat Wstat Total Fail Failed List of Failed
2560 -----------------------------------------------------------------------------
2561 ../ext/B/Deparse.t 14 1 7.14% 14
2562 ../ext/B/Showlex.t 1 1 100.00% 1
2563 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2564 600 602 604-610
2565 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2566 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2567 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2568 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2569 ../lib/warnings.t 434 1 0.23% 75
2570 ../lib/ExtUtils.t 27 1 3.70% 25
2571 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2572 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2573 ../lib/User/pwent.t 9 1 11.11% 4
2574 op/pat.t 660 6 0.91% 242-243 424-425
2575 626-627
2576 op/split.t 0 9 ?? ?? % ??
2577 op/taint.t 174 3 1.72% 156 162 168
2578 op/tr.t 70 3 4.29% 50 58-59
2579 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2580
2581=head2 op/sprintf tests 129 and 130
2582
2583The op/sprintf tests 129 and 130 are known to fail on some platforms.
2584Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2585The failing platforms do not comply with the ANSI C Standard, line
258619ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2587something other than "1" and "-1" when formatting 0.6 and -0.6 using
2588the printf format "%.0f", most often they produce "0" and "-0".)
2589
2590=head2 Failure of Thread tests
2591
fedd8cf1
JH
2592B<Note that support for 5.005-style threading remains experimental
2593and practically unsupported.>
f39f21d8
JH
2594
2595The following tests are known to fail due to fundamental problems in
2596the 5.005 threading implementation. These are not new failures--Perl
25975.005_0x has the same bugs, but didn't have these tests.
2598
fedd8cf1
JH
2599 ext/List/Util/t/first 2
2600 lib/autouse 4
2601 ext/Thread/thr5005 19-20
2602
2603These failures are unlikely to get fixed.
f39f21d8
JH
2604
2605=head2 UNICOS
2606
2607=over 4
2608
2609=item *
2610
2611ext/POSIX/sigaction subtests 6 and 13 may fail.
2612
2613=item *
2614
2615lib/ExtUtils may spuriously claim that subtest 28 failed,
2616which is interesting since the test only has 27 tests.
2617
2618=item *
2619
2620Numerous numerical test failures
2621
2622 op/numconvert 209,210,217,218
2623 op/override 7
2624 ext/Time/HiRes/HiRes 9
2625 lib/Math/BigInt/t/bigintpm 1145
2626 lib/Math/Trig 25
2627
2628These tests fail because of yet unresolved floating point inaccuracies.
2629
2630=back
2631
0968fb3b 2632=head2 UNICOS and UNICOS/mk
0f71e040 2633
0968fb3b
JH
2634The io/fs test #31 is failing because in UNICOS and UNICOS/mk
2635truncate() cannot be used to grow the size of filehandles, only
2636to reduce the size. The workaround is to truncate files instead
2637of filehandles.
0f71e040 2638
f39f21d8
JH
2639=head2 UTS
2640
2641There are a few known test failures, see L<perluts>.
2642
2643=head2 VMS
2644
161720b2
CB
2645There should be no reported test failures with a default configuration,
2646though there are a number of tests marked TODO that point to areas
2647needing further debugging and/or porting work.
7207e29d 2648
f39f21d8
JH
2649=head2 Win32
2650
2651In multi-CPU boxes there are some problems with the I/O buffering:
2652some output may appear twice.
2653
2654=head2 Localising a Tied Variable Leaks Memory
2655
2656 use Tie::Hash;
2657 tie my %tie_hash => 'Tie::StdHash';
2658
2659 ...
2660
2661 local($tie_hash{Foo}) = 1; # leaks
2662
2663Code like the above is known to leak memory every time the local()
2664is executed.
2665
aecce728
JH
2666=head2 Localising Tied Arrays and Hashes Is Broken
2667
2668 local %tied_array;
2669
2670doesn't work as one would expect: the old value is restored
2671incorrectly.
2672
f39f21d8
JH
2673=head2 Self-tying of Arrays and Hashes Is Forbidden
2674
2675Self-tying of arrays and hashes is broken in rather deep and
2676hard-to-fix ways. As a stop-gap measure to avoid people from getting
2677frustrated at the mysterious results (core dumps, most often) it is
2678for now forbidden (you will get a fatal error even from an attempt).
2679
f39f21d8
JH
2680=head2 Building Extensions Can Fail Because Of Largefiles
2681
2682Some extensions like mod_perl are known to have issues with
2683`largefiles', a change brought by Perl 5.6.0 in which file offsets
2684default to 64 bits wide, where supported. Modules may fail to compile
2685at all or compile and work incorrectly. Currently there is no good
2686solution for the problem, but Configure now provides appropriate
2687non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2688hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2689having problems can try configuring themselves without the
2690largefileness. This is admittedly not a clean solution, and the
2691solution may not even work at all. One potential failure is whether
2692one can (or, if one can, whether it's a good idea) link together at
2693all binaries with different ideas about file offsets, all this is
2694platform-dependent.
2695
aecce728
JH
2696=head2 Unicode Support on EBCDIC Still Spotty
2697
2698Though mostly working, Unicode support still has problem spots on
2699EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
2700regular expression constructs for code points less than 256: the
2701pP are testing for Unicode code points, not knowing about EBCDIC.
2702
f39f21d8
JH
2703=head2 The Compiler Suite Is Still Experimental
2704
44da0e71
JH
2705The compiler suite is slowly getting better but it continues to be
2706highly experimental. Use in production environments is discouraged.
f39f21d8 2707
c4f1ce08 2708=head2 The Long Double Support Is Still Experimental
f39f21d8
JH
2709
2710The ability to configure Perl's numbers to use "long doubles",
2711floating point numbers of hopefully better accuracy, is still
2712experimental. The implementations of long doubles are not yet
2713widespread and the existing implementations are not quite mature
2714or standardised, therefore trying to support them is a rare
2715and moving target. The gain of more precision may also be offset
2716by slowdown in computations (more bits to move around, and the
2717operations are more likely to be executed by less optimised
2718libraries).
33a87e58 2719
c4f1ce08
JH
2720=head2 Seen In Perl 5.7 But Gone Now
2721
c4f1ce08
JH
2722C<Time::Piece> (previously known as C<Time::Object>) was removed
2723because it was felt that it didn't have enough value in it to be a
2724core module. It is still a useful module, though, and is available
2725from the CPAN.
2726
cc0fca54
GS
2727=head1 Reporting Bugs
2728
d4ad863d
JH
2729If you find what you think is a bug, you might check the articles
2730recently posted to the comp.lang.perl.misc newsgroup and the perl
2731bug database at http://bugs.perl.org. There may also be
06a5f41f 2732information at http://www.perl.com/, the Perl Home Page.
cc0fca54
GS
2733
2734If you believe you have an unreported bug, please run the B<perlbug>
2735program included with your release. Be sure to trim your bug down
2736to a tiny but sufficient test case. Your bug report, along with the
d4ad863d 2737output of C<perl -V>, will be sent off to perlbug@perl.org to be
cc0fca54
GS
2738analysed by the Perl porting team.
2739
2740=head1 SEE ALSO
2741
2742The F<Changes> file for exhaustive details on what changed.
2743
2744The F<INSTALL> file for how to build Perl.
2745
2746The F<README> file for general stuff.
2747
2748The F<Artistic> and F<Copying> files for copyright information.
2749
2750=head1 HISTORY
2751
d468ca04 2752Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.
cc0fca54
GS
2753
2754=cut