3 perldelta - what is new for perl v5.8.0
7 This document describes differences between the 5.6.0 release and the
10 =head1 Incompatible Changes
16 The semantics of bless(REF, REF) were unclear and until someone proves
17 it to make some sense, it is forbidden.
21 A reference to a reference now stringify as "REF(0x81485ec)" instead
22 of "SCALAR(0x81485ec)" in order to be more consistent with the return
27 The very dusty examples in the eg/ directory have been removed.
28 Suggestions for new shiny examples welcome but the main issue is that
29 the examples need to be documented, tested and (most importantly)
34 The obsolete chat2 library that should never have been allowed
35 to escape the laboratory has been decommissioned.
39 The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
40 recognised but now cause fatal errors. The previous behaviour of
41 ignoring them by default and warning if requested was unacceptable
42 since it, in a way, falsely promised that the features could be used.
46 The (bogus) escape sequences \8 and \9 now give an optional warning
47 ("Unrecognized escape passed through"). There is no need to \-escape
52 lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
53 In future releases this may become a fatal error.
57 The long deprecated uppercase aliases for the string comparison
58 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
62 The regular expression captured submatches ($1, $2, ...) are now
63 more consistently unset if the match fails, instead of leaving false
64 data lying around in them.
68 The tr///C and tr///U features have been removed and will not return;
69 the interface was a mistake. Sorry about that. For similar
70 functionality, see pack('U0', ...) and pack('C0', ...).
74 Although "you shouldn't do that", it was possible to write code that
75 depends on Perl's hashed key order (Data::Dumper does this). The new
76 algorithm "One-at-a-Time" produces a different hashed key order.
77 More details are in L</"Performance Enhancements">.
81 The list of filenames from glob() (or <...>) is now by default sorted
82 alphabetically to be csh-compliant. (bsd_glob() does still sort platform
83 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
87 =head2 64-bit platforms and malloc
89 If your pointers are 64 bits wide, the Perl malloc is no more being
90 used because it simply does not work with 8-byte pointers. Also,
91 usually the system malloc on such platforms are much better optimized
92 for such large memory models than the Perl malloc.
94 =head2 AIX Dynaloading
96 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
97 dlopen interface of AIX instead of the old emulated interface. This
98 change will probably break backward compatibility with compiled
99 modules. The change was made to make Perl more compliant with other
100 applications like modperl which are using the AIX native interface.
102 =head2 Socket Extension Dynamic in VMS
104 The Socket extension is now dynamically loaded instead of being
105 statically built in. This may or may not be a problem with ancient
106 TCP/IP stacks of VMS: we do not know since we weren't able to test
107 Perl in such configurations.
109 =head2 Different Definition of the Unicode Character Classes \p{In...}
111 As suggested by the Unicode consortium, the Unicode character classes
112 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
113 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
114 constructs are used. This has changed the definition of some of those
117 The difference between scripts and blocks is that scripts are the
118 glyphs used by a language or a group of languages, while the blocks
119 are more artificial groupings of 256 characters based on the Unicode
122 In general this change results in more inclusive Unicode character
123 classes, but changes to the other direction also do take place:
124 for example while the script C<Latin> includes all the Latin
125 characters and their various diacritic-adorned versions, it
126 does not include the various punctuation or digits (since they
127 are not solely C<Latin>).
129 Changes in the character class semantics may have happened if a script
130 and a block happen to have the same name, for example C<Hebrew>.
131 In such cases the script wins and C<\p{InHebrew}> now means the script
132 definition of Hebrew. The block definition in still available,
133 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
134 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
135 of affected character classes, see L<perlunicode/Blocks>.
139 The current user-visible implementation of pseudo-hashes (the weird
140 use of the first array element) is deprecated starting from Perl 5.8.0
141 and will be removed in Perl 5.10.0, and the feature will be
142 implemented differently. Not only is the current interface rather
143 ugly, but the current implementation slows down normal array and hash
144 use quite noticeably. The C<fields> pragma interface will remain
147 The syntaxes C<@a->[...]> and C<@h->{...}> have now been deprecated.
149 The suidperl is also considered to be too much a risk to continue
150 maintaining and the suidperl code is likely to be removed in a future
153 The C<package;> syntax (C<package> without an argument has been
154 deprecated. Its semantics were never that clear and its
155 implementation even less so. If you have used that feature to
156 disallow all but fully qualified variables, C<use strict;> instead.
158 The chdir(undef) and chdir('') behaviors to match chdir() has been
159 deprecated. In future versions, chdir(undef) and chdir('') will
162 =head1 Core Enhancements
168 C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
169 in multiple arguments.)
173 my __PACKAGE__ $obj now works.
177 C<no Module;> now works even if there is no "sub unimport" in the Module.
181 The numerical comparison operators return C<undef> if either operand
182 is a NaN. Previously the behaviour was unspecified.
186 C<pack('U0a*', ...)> can now be used to force a string to UTF8.
190 prototype(\&) is now available.
194 There is now an UNTIE method.
198 =head2 AUTOLOAD Is Now Lvaluable
200 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
201 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
203 =head2 PerlIO is Now The Default
209 IO is now by default done via PerlIO rather than system's "stdio".
210 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
211 handle's behaviour. Layers can be specified at open time via 3-arg
214 open($fh,'>:crlf :utf8', $path) || ...
216 or on already opened handles via extended C<binmode>:
218 binmode($fh,':encoding(iso-8859-7)');
220 The built-in layers are: unix (low level read/write), stdio (as in
221 previous Perls), perlio (re-implementation of stdio buffering in a
222 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
223 but available on any platform). A mmap layer may be available if
224 platform supports it (mostly UNIXes).
226 Layers to be applied by default may be specified via the 'open' pragma.
228 See L</"Installation and Configuration Improvements"> for the effects
229 of PerlIO on your architecture name.
233 File handles can be marked as accepting Perl's internal encoding of Unicode
234 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
236 open($fh,">:utf8","Uni.txt");
238 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
239 for you since it's not UTF-8 what you will be getting but instead
240 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
241 http://www.unicode.org/unicode/reports/tr16/ for more information.
242 In future releases this naming may change.
246 File handles can translate character encodings from/to Perl's internal
247 Unicode form on read/write via the ":encoding()" layer.
251 File handles can be opened to "in memory" files held in Perl scalars via:
253 open($fh,'>', \$variable) || ...
257 Anonymous temporary files are available without need to
258 'use FileHandle' or other module via
260 open($fh,"+>", undef) || ...
262 That is a literal undef, not an undefined value.
266 The list form of C<open> is now implemented for pipes (at least on UNIX):
268 open($fh,"-|", 'cat', '/etc/motd')
270 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
275 The following builtin functions are now overridable: chop(), chomp(),
276 each(), keys(), pop(), push(), shift(), splice(), unshift().
280 Formats now support zero-padded decimal fields.
284 Perl now tries internally to use integer values in numeric conversions
285 and basic arithmetics (+ - * /) if the arguments are integers, and
286 tries also to keep the results stored internally as integers.
287 This change leads into often slightly faster and always less lossy
288 arithmetics. (Previously Perl always preferred floating point numbers
293 The printf() and sprintf() now support parameter reordering using the
294 C<%\d+\$> and C<*\d+\$> syntaxes. For example
296 print "%2\$s %1\$s\n", "foo", "bar";
298 will print "bar foo\n"; This feature helps in writing
299 internationalised software.
303 Unicode in general should be now much more usable. Unicode can be
304 used in hash keys, Unicode in regular expressions should work now,
305 Unicode in tr/// should work now (though tr/// seems to be a
306 particularly tricky to get right, so you have been warned)
310 The Unicode Character Database coming with Perl has been upgraded
311 to Unicode 3.1. For more information, see http://www.unicode.org/,
312 and http://www.unicode.org/unicode/reports/tr27/
314 For developers interested in enhancing Perl's Unicode capabilities:
315 almost all the UCD files are included with the Perl distribution in
316 the lib/unicode subdirectory. The most notable omission, for space
317 considerations, is the Unihan database.
321 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
322 added. "Blank" is like C isblank(), that is, it contains only
323 "horizontal whitespace" (the space character is, the newline isn't),
324 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
325 isn't, since that includes the vertical tabulator character, whereas
330 =head2 Signals Are Now Safe
332 Perl used to be fragile in that signals arriving at inopportune moments
333 could corrupt Perl's internal state.
335 =head2 Understanding of Numbers
337 In general a lot of fixing has happened in the area of Perl's
338 understanding of numbers, both integer and floating point. Since in
339 many systems the standard number parsing functions like C<strtoul()>
340 and C<atof()> seem to have bugs, Perl tries to work around their
341 deficiencies. This results hopefully in more accurate numbers.
347 The rules for allowing underscores (underbars) in numeric constants
348 have been relaxed and simplified: now you can have an underscore
353 GMAGIC (right-hand side magic) could in many cases such as string
354 concatenation be invoked too many times.
358 Lexicals I: lexicals outside an eval "" weren't resolved
359 correctly inside a subroutine definition inside the eval "" if they
360 were not already referenced in the top level of the eval""ed code.
364 Lexicals II: lexicals leaked at file scope into subroutines that
365 were declared before the lexicals.
369 Lvalue subroutines can now return C<undef> in list context.
373 The C<op_clear> and C<op_null> are now exported.
377 A new special regular expression variable has been introduced:
378 C<$^N>, which contains the most-recently closed group (submatch).
382 L<utime> now supports C<utime undef, undef, @files> to change the
383 file timestamps to the current time.
387 The Perl parser has been stress tested using both random input and
392 C<eval "v200"> now works.
396 VMS now works under PerlIO.
400 END blocks are now run even if you exit/die in a BEGIN block.
401 The execution of END blocks is now controlled by
402 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
403 behaviour for perl embedders. This will default in 5.10. See
408 =head1 Modules and Pragmata
416 File::Temp allows one to create temporary files and directories in an
417 easy, portable, and secure way.
421 Storable gives persistence to Perl data structures by allowing the
422 storage and retrieval of Perl data to and from files in a fast and
423 compact binary format.
427 B::Concise, by Stephen McCamant, is a new compiler backend for
428 walking the Perl syntax tree, printing concise info about ops.
429 The output is highly customisable.
431 See L<B::Concise> for more information.
435 Class::ISA, by Sean Burke, for reporting the search path for a
436 class's ISA tree, has been added.
438 See L<Class::ISA> for more information.
442 Cwd has now a split personality: if possible, an extension is used,
443 (this will hopefully be both faster and more secure and robust) but
444 if not possible, the familiar Perl library implementation is used.
448 Digest, a frontend module for calculating digests (checksums),
449 from Gisle Aas, has been added.
451 See L<Digest> for more information.
455 Digest::MD5 for calculating MD5 digests (checksums), by Gisle Aas,
458 use Digest::MD5 'md5_hex';
460 $digest = md5_hex("Thirsty Camel");
462 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
464 NOTE: the MD5 backward compatibility module is deliberately not
465 included since its use is discouraged.
467 See L<Digest::MD5> for more information.
471 Encode, by Nick Ing-Simmons, provides a mechanism to translate
472 between different character encodings. Support for Unicode,
473 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
474 compiled in to the module. Several other encodings (like Japanese,
475 Chinese, and MacIntosh encodings) are included and will be loaded at
478 Any encoding supported by Encode module is also available to the
479 ":encoding()" layer if PerlIO is used.
481 See L<Encode> for more information.
485 Filter::Simple is an easy-to-use frontend to Filter::Util::Call,
492 use Filter::Simple sub {
493 while (my ($from, $to) = splice @_, 0, 2) {
502 use MyFilter qr/red/ => 'green';
504 print "red\n"; # this code is filtered, will print "green\n"
505 print "bored\n"; # this code is filtered, will print "bogreen\n"
509 print "red\n"; # this code is not filtered, will print "red\n"
511 See L<Filter::Simple> for more information.
515 Filter::Util::Call, by Paul Marquess, provides you with the
516 framework to write I<Source Filters> in Perl. For most uses
517 the frontend Filter::Simple is to be preferred.
518 See L<Filter::Util::Call> for more information.
522 Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language,
523 from Neil Bowers, have been added. They provide the codes for various
524 locale standards, such as "fr" for France, "usd" for US Dollar, and
529 $country = code2country('jp'); # $country gets 'Japan'
530 $code = country2code('Norway'); # $code gets 'no'
532 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
533 and L<Locale::Language> for more information.
537 MIME::Base64, by Gisle Aas, allows you to encode data in base64.
541 $encoded = encode_base64('Aladdin:open sesame');
542 $decoded = decode_base64($encoded);
544 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
546 See L<MIME::Base64> for more information.
550 MIME::QuotedPrint, by Gisle Aas, allows you to encode data in
551 quoted-printable encoding.
553 use MIME::QuotedPrint;
555 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
556 $decoded = decode_qp($encoded);
558 print $encoded, "\n"; # "Smiley in Unicode: =263A"
560 MIME::QuotedPrint has been enhanced to provide the basic methods
561 necessary to use it with PerlIO::Via as in :
563 use MIME::QuotedPrint;
564 open($fh,">Via(MIME::QuotedPrint)",$path)
566 See L<MIME::QuotedPrint> for more information.
570 PerlIO::Scalar, by Nick Ing-Simmons, provides the implementation of
571 IO to "in memory" Perl scalars as discussed above. It also serves as
572 an example of a loadable layer. Other future possibilities include
573 PerlIO::Array and PerlIO::Code. See L<PerlIO::Scalar> for more
578 PerlIO::Via, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
579 PerlIO layer functionality provided by a class (typically implemented
582 use MIME::QuotedPrint;
583 open($fh,">Via(MIME::QuotedPrint)",$path)
585 This will automatically convert everything output to C<$fh>
586 to Quoted-Printable. See L<PerlIO::Via> for more information.
590 Pod::Text::Overstrike, by Joe Smith, has been added.
591 It converts POD data to formatted overstrike text.
592 See L<Pod::Text::Overstrike> for more information.
596 Switch from Damian Conway has been added. Just by saying
600 you have C<switch> and C<case> available in Perl.
606 case 1 { print "number 1" }
607 case "a" { print "string a" }
608 case [1..10,42] { print "number in list" }
609 case (@array) { print "number in list" }
610 case /\w+/ { print "pattern" }
611 case qr/\w+/ { print "pattern" }
612 case (%hash) { print "entry in hash" }
613 case (\%hash) { print "entry in hash" }
614 case (\&sub) { print "arg to subroutine" }
615 else { print "previous case not true" }
618 See L<Switch> for more information.
622 Text::Balanced from Damian Conway has been added, for
623 extracting delimited text sequences from strings.
625 use Text::Balanced 'extract_delimited';
627 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
629 $a will be "'never say never'", $b will be ', he never said'.
631 In addition to extract_delimited() there are also extract_bracketed(),
632 extract_quotelike(), extract_codeblock(), extract_variable(),
633 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
634 gen_extract_tagged(). With these you can implement rather advanced
635 parsing algorithms. See L<Text::Balanced> for more information.
639 Tie::RefHash::Nestable, by Edward Avis, allows storing hash references
640 (unlike the standard Tie::RefHash) The module is contained within
645 XS::Typemap, by Tim Jenness, is a test extension that exercises XS
646 typemaps. Nothing gets installed but for extension writers the code
651 L<Attribute::Handlers> - Simpler definition of attribute handlers
655 L<ExtUtils::Constant> - generate XS code to import C header constants
659 L<I18N::Langinfo> - query locale information
663 L<I18N::LangTags> - functions for dealing with RFC3066-style language tags
667 L<libnet> - a collection of perl5 modules related to network programming
669 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
673 L<List::Util> - selection of general-utility list subroutines
677 L<Locale::Maketext> - framework for localization
681 L<Memoize> - Make your functions faster by trading space for time
685 L<NEXT> - pseudo-class for method redispatch
689 L<Scalar::Util> - selection of general-utility scalar subroutines
693 L<Test::More> - yet another framework for writing test scripts
697 L<Test::Simple> - Basic utilities for writing tests
701 L<threads> - interpreter threads
705 L<threads::shared> - data sharing for interpreter threads
709 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
713 L<Time::Piece> - Object Oriented time objects
715 (Previously known as L<Time::Object>.)
719 L<Time::Seconds> - a simple API to convert seconds to other date values
723 L<Unicode::CD> - Unicode Character Database
727 Unicode::Collate - Unicode collation
731 Unicode::Normalize - Unicode normalization
735 =head2 Updated And Improved Modules and Pragmata
741 The following independently supported modules have been updated to
742 newer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
743 the podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
747 Bug fixes and minor enhancements have been applied to B::Deparse,
748 Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
749 Math::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
750 Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
755 The attributes::reftype() now works on tied arguments.
759 AutoLoader can now be disabled with C<no AutoLoader;>,
763 The English module can now be used without the infamous performance
766 use English '-no_performance_hit';
768 (Assuming, of course, that one doesn't need the troublesome variables
769 C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
770 C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
774 File::Find now has pre- and post-processing callbacks. It also
775 correctly changes directories when chasing symbolic links. Callbacks
776 (naughtily) exiting with "next;" instead of "return;" now work.
780 File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
781 prototype mismatch with CORE::glob().
785 IPC::Open3 now allows the use of numeric file descriptors.
789 use lib now works identically to @INC. Removing directories
790 with 'no lib' now works.
794 C<%INC> now localised in a Safe compartment so that use/require work.
798 The Shell module now has an OO interface.
802 B::Deparse should be now more robust. It still far from providing a full
803 round trip for any random piece of Perl code, though, and is under active
804 development: expect more robustness in 5.7.2.
808 Class::Struct can now define the classes in compile time.
812 Math::BigFloat has undergone much fixing, and in addition the fmod()
813 function now supports modulus operations.
815 (The fixed Math::BigFloat module is also available in CPAN for those
816 who can't upgrade their Perl: http://www.cpan.org/authors/id/J/JP/JPEACOCK/)
820 Devel::Peek now has an interface for the Perl memory statistics
821 (this works only if you are using perl's malloc, and if you have
822 compiled with debugging).
826 IO::Socket has now atmark() method, which returns true if the socket
827 is positioned at the out-of-band mark. The method is also exportable
828 as a sockatmark() function.
832 IO::Socket::INET has support for ReusePort option (if your platform
833 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
834 you may want to prefer ReuseAddr.
838 Net::Ping has been enhanced. There is now "external" protocol which
839 uses Net::Ping::External module which runs external ping(1) and parses
840 the output. An alpha version of Net::Ping::External is available in
841 CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
845 The C<open> pragma allows layers other than ":raw" and ":crlf" when
850 POSIX::sigaction() is now much more flexible and robust.
851 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
852 handlers, installing new handlers was not atomic.
856 The Test module has been significantly enhanced. Its use is
857 greatly recommended for module writers.
861 The utf8:: name space (as in the pragma) provides various
862 Perl-callable functions to provide low level access to Perl's
863 internal Unicode representation. At the moment only length()
864 has been implemented.
868 The following modules have been upgraded from the versions at CPAN:
869 CPAN, CGI, DB_File, File::Temp, Getopt::Long, Pod::Man, Pod::Text,
870 Storable, Text-Tabs+Wrap.
874 L<B::Deparse> module has been significantly enhanced. It now
875 can deparse almost all of the standard test suite (so that the
876 tests still succeed). There is a make target "test.deparse"
881 L<Class::Struct> now assigns the array/hash element if the accessor
882 is called with an array/hash element as the B<sole> argument.
886 L<Cwd> extension is now (even) faster.
890 L<DB_File> extension has been updated to version 1.77.
894 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
895 new-style constant dispatch section (see L<ExtUtils::Constant>).
899 L<File::Find> is now (again) reentrant. It also has been made
904 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
905 size of the returned list of filenames.
909 L<IO::Socket::INET> now supports C<LocalPort> of zero (usually meaning
910 that the operating system will make one up.)
914 The L<vars> pragma now supports declaring fully qualified variables.
915 (Something that C<our()> does not and will not support.)
919 List::Util now has shuffle() for randomizing a list.
923 =head1 Utility Changes
929 The Emacs perl mode (emacs/cperl-mode.el) has been updated to version
934 Perlbug is now much more robust. It also sends the bug report to
935 perl.org, not perl.com.
939 The perlcc utility has been rewritten and its user interface (that is,
940 command line) is much more like that of the UNIX C compiler, cc.
944 The xsubpp utility for extension writers now understands POD
945 documentation embedded in the *.xs files.
949 h2xs now produces template README.
953 s2p has been completely rewritten in Perl. (It is in fact a full
954 implementation of sed in Perl.)
958 xsubpp now supports OUT keyword.
962 The F<emacs/e2ctags.pl> is now much faster.
966 L<h2ph> now supports C trigraphs.
970 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
971 newly created extensions that define constants. Since the new code is
972 more correct (if you have two constants where the first one is a
973 prefix of the second one, the first constant B<never> gets defined),
974 less lossy (it uses integers for integer constant, as opposed to the
975 old code that used floating point numbers even for integer constants),
976 and slightly faster, you might want to consider regenerating your
977 extension code (the new scheme makes regenerating easy).
978 L<h2xs> now also supports C trigraphs.
982 L<libnetcfg> has been added to configure the libnet.
986 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
991 =head1 New Documentation
997 perl56delta details the changes between the 5.005 release and the
1002 perldebtut is a Perl debugging tutorial.
1006 perlebcdic contains considerations for running Perl on EBCDIC platforms.
1007 Note that unfortunately EBCDIC platforms that used to supported back in
1008 Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
1009 bring them back to the fold.
1013 perlintro is a gentle introduction to Perl.
1017 perlmodstyle is a style guide for writing modules.
1021 perlnewmod tells about writing and submitting a new module.
1025 perlpod has been rewritten to be clearer and to record the best
1026 practices gathered over the years.
1030 perlpodstyle is a more formal specification of the pod format,
1031 mainly of interest for writers of pod applications, not to
1032 people writing in pod.
1036 perlposix-bc explains using Perl on the POSIX-BC platform
1037 (an EBCDIC mainframe platform).
1041 perlretut is a regular expression tutorial.
1045 perlrequick is a regular expressions quick-start guide.
1046 Yes, much quicker than perlretut.
1050 perltootc has been renamed as perltooc (to not to conflict
1051 with perltoot in filesystem restricted to "8.3" names)
1055 perluniintro is an introduction to using Unicode in Perl
1056 (perlunicode is more of a reference)
1060 perlutil explains the command line utilities packaged with the Perl
1067 Internal replacements for standard C library functions.
1068 (Interesting only for extension writers and Perl core hackers.)
1072 Internals of PerlIO with layers.
1076 Documentation on compiling Perl on AIX has been added. AIX has
1077 several different C compilers and getting the right patch level
1078 is essential. On install README.aix will be installed as L<perlaix>.
1080 =head2 README.bs2000
1082 Documentation on compiling Perl on the POSIX-BC platform (an EBCDIC
1083 mainframe environment) has been added.
1085 This was formerly known as README.posix-bc but the name was considered
1086 to be too confusing (it has nothing to do with the POSIX module or the
1087 POSIX standard). On install README.bs2000 will be installed as L<perlbs2000>.
1091 In perl 5.7.1 (and in the 5.6.1) the MacPerl sources have been
1092 synchronised with the standard Perl sources. To compile MacPerl
1093 some additional steps are required, and this file documents those
1094 steps. On install README.macos will be installed as L<perlmacos>.
1098 The README.mpeix has been podified, which means that this information
1099 about compiling and using Perl on the MPE/iX miniframe platform will
1100 be installed as L<perlmpeix>.
1102 =head2 README.solaris
1104 README.solaris has been created and Solaris wisdom from elsewhere
1105 in the Perl documentation has been collected there. On install
1106 README.solaris will be installed as L<perlsolaris>.
1110 The README.vos has been podified, which means that this information
1111 about compiling and using Perl on the Stratus VOS miniframe platform
1112 will be installed as L<perlvos>.
1114 =head2 Porting/repository.pod
1116 Documentation on how to use the Perl source repository has been added.
1122 L<Locale::Maketext::TPJ13> is an article about software localization,
1123 originally published in The Perl Journal #13, republished here with
1128 More README.$PLATFORM files have been converted into pod, which also
1129 means that they also be installed as perl$PLATFORM documentation
1130 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
1131 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
1136 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
1140 Use of the F<gprof> tool to profile Perl has been documented in
1141 L<perlhack>. There is a make target "perl.gprof" for generating a
1142 gprofiled Perl executable.
1146 =head1 Performance Enhancements
1152 map() that changes the size of the list should now work faster.
1156 sort() has been changed to use mergesort internally as opposed to the
1157 earlier quicksort. For very small lists this may result in slightly
1158 slower sorting times, but in general the speedup should be at least
1159 20%. Additional bonuses are that the worst case behaviour of sort()
1160 is now better (in computer science terms it now runs in time O(N log N),
1161 as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
1162 and that sort() is now stable (meaning that elements with identical
1163 keys will stay ordered as they were before the sort).
1167 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
1168 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
1169 reasonably fast while producing a much better spread of values than
1170 the old hashing algorithm (originally by Chris Torek, later tweaked by
1171 Ilya Zakharevich). Hash values output from the algorithm on a hash of
1172 all 3-char printable ASCII keys comes much closer to passing the
1173 DIEHARD random number generation tests. According to perlbench, this
1174 change has not affected the overall speed of Perl.
1178 unshift() should now be noticeably faster.
1182 =head1 Installation and Configuration Improvements
1184 =head2 Generic Improvements
1190 INSTALL now explains how you can configure Perl to use 64-bit
1191 integers even on non-64-bit platforms.
1195 Policy.sh policy change: if you are reusing a Policy.sh file
1196 (see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
1197 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1198 them will now be changed to the new prefix, /foo/bar. (Previously
1199 only $prefix changed.) If you do not like this new behaviour,
1200 specify prefix, siteprefix, and vendorprefix explicitly.
1204 A new optional location for Perl libraries, otherlibdirs, is available.
1205 It can be used for example for vendor add-ons without disturbing Perl's
1206 own library directories.
1210 In many platforms the vendor-supplied 'cc' is too stripped-down to
1211 build Perl (basically, 'cc' doesn't do ANSI C). If this seems
1212 to be the case and 'cc' does not seem to be the GNU C compiler
1213 'gcc', an automatic attempt is made to find and use 'gcc' instead.
1217 gcc needs to closely track the operating system release to avoid
1218 build problems. If Configure finds that gcc was built for a different
1219 operating system release than is running, it now gives a clearly visible
1220 warning that there may be trouble ahead.
1224 If binary compatibility with the 5.005 release is not wanted, Configure
1225 no longer suggests including the 5.005 modules in @INC.
1229 Configure C<-S> can now run non-interactively.
1233 configure.gnu now works with options with whitespace in them.
1237 installperl now outputs everything to STDERR.
1241 $Config{byteorder} is now computed dynamically (this is more robust
1242 with "fat binaries" where an executable image contains binaries for
1243 more than one binary platform.)
1247 Because PerlIO is now the default on most platforms, "-perlio" doesn't
1248 get appended to the $Config{archname} (also known as $^O) anymore.
1249 Instead, if you explicitly choose not to use perlio (Configure command
1250 line option -Uuseperlio), you will get "-stdio" appended.
1254 Another change related to the architecture name is that "-64all"
1255 (-Duse64bitall, or "maximally 64-bit") is appended only if your
1256 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
1260 APPLLIB_EXP, a less-know configuration-time definition, has been
1261 documented. It can be used to prepend site-specific directories
1262 to Perl's default search path (@INC), see INSTALL for information.
1266 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
1267 has been documented in INSTALL.
1271 If you are on IRIX or Tru64 platforms, new profiling/debugging options
1272 have been added, see L<perlhack> for more information about pixie and
1277 In AFS installations one can configure the root of the AFS to be
1278 somewhere else than the default F</afs> by using the Configure
1279 parameter C<-Dafsroot=/some/where/else>.
1283 The version of Berkeley DB used when the Perl (and, presumably, the
1284 DB_File extension) was built is now available as
1285 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
1286 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
1287 DB_VERSION_PATCH_CFG> from C.
1291 The Thread extension is now not built at all under ithreads
1292 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
1293 Thread extension requires being Configured with C<-Duse5005threads>).
1297 The C<B::Deparse> compiler backend has been so significantly improved
1298 that almost the whole Perl test suite passes after being deparsed. A
1299 make target has been added to help in further testing: C<make test.deparse>.
1303 =head2 New Or Improved Platforms
1305 For the list of platforms known to support Perl,
1306 see L<perlport/"Supported Platforms">.
1312 AIX dynamic loading should be now better supported.
1316 After a long pause, AmigaOS has been verified to be happy with Perl.
1320 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
1321 have been regained. Many test suite tests still fail and the
1322 co-existence of Unicode and EBCDIC isn't quite settled, but the
1323 situation is much better than with Perl 5.6. See L<perlos390>,
1324 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
1328 Building perl with -Duseithreads or -Duse5005threads now works under
1329 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
1330 need a thread library package installed. See README.hpux.
1334 MacOS Classic (MacPerl has of course been available since
1335 perl 5.004 but now the source code bases of standard Perl
1336 and MacPerl have been synchronised)
1340 NCR MP-RAS is now supported.
1344 NonStop-UX is now supported.
1348 Amdahl UTS is now supported.
1352 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
1353 support for dynamic loading. This is not selected by default,
1354 however, you must specify -Dusedl in the arguments of Configure.
1358 AIX should now work better with gcc, threads, and 64-bitness. Also the
1359 long doubles support in AIX should be better now. See L<perlaix>.
1363 AtheOS (http://www.atheos.cx/) is a new platform.
1367 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
1371 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
1375 Several MacOS (Classic) portability patches have been applied. We
1376 hope to get a fully working port by 5.8.0. (The remaining problems
1377 relate to the changed IO model of Perl.) See L<perlmacos>.
1381 MacOS X (or Darwin) should now be able to build Perl even on HFS+
1382 filesystems. (The case-insensitivity confused the Perl build process.)
1386 NetWare from Novell is now supported. See L<perlnetware>.
1390 The Amdahl UTS UNIX mainframe platform is now supported.
1394 WinCE is now supported. See L<perlce>.
1398 If you have CPAN access you can during specify extra modules to
1399 Configure to build and install with Perl using the -Dextras=...
1400 option. See INSTALL for more details.
1404 In addition to config.over a new override file, config.arch, is
1405 available. That is supposed to be used by hints file writers for
1406 architecture-wide changes (as opposed to config.over which is for
1411 Guidelines of how to construct minimal Perl installations have
1412 been added to INSTALL.
1416 For Perl developers several new make targets for profiling
1417 have been added, see L<perlhack>.
1421 =head1 Selected Bug Fixes
1427 Several debugger fixes: exit code now reflects the script exit code,
1428 condition C<"0"> now treated correctly, the C<d> command now checks
1429 line number, the C<$.> no longer gets corrupted, all debugger output now
1430 goes correctly to the socket if RemotePort is set.
1434 C<*foo{FORMAT}> now works.
1438 Lexical warnings now propagating correctly between scopes.
1442 Line renumbering with eval and C<#line> now works.
1446 Fixed numerous memory leaks, especially in eval "".
1450 Modulus of unsigned numbers now works (4063328477 % 65535 used to
1451 return 27406, instead of 27047).
1455 Some "not a number" warnings introduced in 5.6.0 eliminated to be
1456 more compatible with 5.005. Infinity is now recognised as a number.
1460 our() variables will not cause "will not stay shared" warnings.
1464 pack "Z" now correctly terminates the string with "\0".
1468 Fix password routines which in some shadow password platforms
1469 (e.g. HP-UX) caused getpwent() to return every other entry.
1473 printf() no longer resets the numeric locale to "C".
1477 C<q(a\\b)> now parses correctly as C<'a\\b'>.
1481 Printing quads (64-bit integers) with printf/sprintf now works
1482 without the q L ll prefixes (assuming you are on a quad-capable platform).
1486 Regular expressions on references and overloaded scalars now work.
1490 scalar() now forces scalar context even when used in void context.
1494 sort() arguments are now compiled in the right wantarray context
1495 (they were accidentally using the context of the sort() itself).
1499 Changed the POSIX character class C<[[:space:]]> to include the (very
1500 rare) vertical tab character. Added a new POSIX-ish character class
1501 C<[[:blank:]]> which stands for horizontal whitespace (currently,
1502 the space and the tab).
1506 $AUTOLOAD, sort(), lock(), and spawning subprocesses
1507 in multiple threads simultaneously are now thread-safe.
1511 Allow read-only string on left hand side of non-modifying tr///.
1515 Several Unicode fixes (but still not perfect).
1521 BOMs (byte order marks) in the beginning of Perl files
1522 (scripts, modules) should now be transparently skipped.
1523 UTF-16 (UCS-2) encoded Perl files should now be read correctly.
1527 The character tables have been updated to Unicode 3.0.1.
1531 chr() for values greater than 127 now create utf8 when under use
1536 Comparing with utf8 data does not magically upgrade non-utf8 data into
1541 C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1545 Concatenation with the C<.> operator or via variable interpolation,
1546 C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1547 substitution with C<s///>, single-quoted UTF8, should now work--in
1552 The C<tr///> operator now works I<slightly> better but is still rather
1553 broken. Note that the C<tr///CU> functionality has been removed (but
1554 see pack('U0', ...)).
1558 vec() now refuses to deal with characters >255.
1562 Zero entries were missing from the Unicode classes like C<IsDigit>.
1568 UNIVERSAL::isa no longer caches methods incorrectly. (This broke
1569 the Tk extension with 5.6.0.)
1573 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
1574 when building the Perl binary. The only exception to this is SunOS 4.x,
1579 Some new Configure symbols, useful for extension writers:
1587 =item d_fcntl_can_lock
1589 Whether fcntl() can be used for file locking.
1597 For getpagesize(), though you should prefer POSIX::sysconf(_SC_PAGE_SIZE))
1605 Whether one needs to use Perl_va_copy() to copy varargs.
1615 The number of elements in an array needed to hold all the available signals.
1623 Whether one needs to access character data aligned by U32 sized pointers.
1633 Removed Configure symbols: the PDP-11 memory model settings: huge,
1634 large, medium, models.
1638 SOCKS support is now much more robust.
1642 If your file system supports symbolic links you can build Perl outside
1643 of the source directory by
1645 mkdir /tmp/perl/build/directory
1646 cd /tmp/perl/build/directory
1647 sh /path/to/perl/source/Configure -Dmksymlinks ...
1649 This will create in /tmp/perl/build/directory a tree of symbolic links
1650 pointing to files in /path/to/perl/source. The original files are left
1651 unaffected. After Configure has finished you can just say
1655 and Perl will be built and tested, all in /tmp/perl/build/directory.
1659 =head2 Platform Specific Changes and Fixes
1667 Perl now works on post-4.0 BSD/OSes.
1673 Setting C<$0> now works (as much as possible; see perlvar for details).
1679 Numerous updates; currently synchronised with Cygwin 1.1.4.
1685 EPOC update after Perl 5.6.0. See README.epoc.
1691 Perl now works on post-3.0 FreeBSDs.
1697 README.hpux updated; C<Configure -Duse64bitall> now almost works.
1703 Numerous compilation flag and hint enhancements; accidental mixing
1704 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1710 Long doubles should now work (see INSTALL).
1716 Compilation of the standard Perl distribution in MacOS Classic should
1717 now work if you have the Metrowerks development environment and
1718 the missing Mac-specific toolkit bits. Contact the macperl mailing
1725 MPE/iX update after Perl 5.6.0. See README.mpeix.
1731 Perl now works on NetBSD/sparc.
1737 Now works with usethreads (see INSTALL).
1743 64-bitness using the Sun Workshop compiler now works.
1747 Tru64 (aka Digital UNIX, aka DEC OSF/1)
1749 The operating system version letter now recorded in $Config{osvers}.
1750 Allow compiling with gcc (previously explicitly forbidden). Compiling
1751 with gcc still not recommended because buggy code results, even with
1758 Fixed various alignment problems that lead into core dumps either
1759 during build or later; no longer dies on math errors at runtime;
1760 now using full quad integers (64 bits), previously was using
1761 only 46 bit integers for speed.
1767 chdir() now works better despite a CRT bug; now works with MULTIPLICITY
1768 (see INSTALL); now works with Perl's malloc.
1778 accept() no longer leaks memory.
1782 Better chdir() return value for a non-existent directory.
1786 New %ENV entries now propagate to subprocesses.
1790 $ENV{LIB} now used to search for libs under Visual C.
1794 A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
1798 Allow REG_EXPAND_SZ keys in the registry.
1802 Can now send() from all threads, not just the first one.
1806 Fake signal handling reenabled, bugs and all.
1810 Less stack reserved per thread so that more threads can run
1811 concurrently. (Still 16M per thread.)
1815 C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
1816 (works better when perl is running as service).
1820 Better UNC path handling under ithreads.
1824 wait() and waitpid() now work much better.
1828 winsock handle leak fixed.
1834 =head1 New or Changed Diagnostics
1836 All regular expression compilation error messages are now hopefully
1837 easier to understand both because the error message now comes before
1838 the failed regex and because the point of failure is now clearly
1841 The various "opened only for", "on closed", "never opened" warnings
1842 drop the C<main::> prefix for filehandles in the C<main> package,
1843 for example C<STDIN> instead of <main::STDIN>.
1845 The "Unrecognized escape" warning has been extended to include C<\8>,
1846 C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
1850 Two new debugging options have been added: if you have compiled your
1851 Perl with debugging, you can use the -DT and -DR options to trace
1852 tokenising and to add reference counts to displaying variables,
1857 If an attempt to use a (non-blessed) reference as an array index
1858 is made, a warning is given.
1862 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
1863 now give a warning. This may be a problem for generated and evaled
1868 =head1 Changed Internals
1874 perlapi.pod (a companion to perlguts) now attempts to document the
1879 You can now build a really minimal perl called microperl.
1880 Building microperl does not require even running Configure;
1881 C<make -f Makefile.micro> should be enough. Beware: microperl makes
1882 many assumptions, some of which may be too bold; the resulting
1883 executable may crash or otherwise misbehave in wondrous ways.
1884 For careful hackers only.
1888 Added rsignal(), whichsig(), do_join() to the publicised API.
1892 Made possible to propagate customised exceptions via croak()ing.
1896 Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
1900 Now xsubs can have attributes just like subs.
1904 Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
1905 For the full list of the available APIs see L<perlapi>.
1909 dTHR and djSP have been obsoleted; the former removed (because it's
1910 a no-op) and the latter replaced with dSP.
1914 Perl now uses system malloc instead of Perl malloc on all 64-bit
1915 platforms, and even in some not-always-64-bit platforms like AIX,
1916 IRIX, and Solaris. This change breaks backward compatibility but
1917 Perl's malloc has problems with large address spaces and also the
1918 speed of vendors' malloc is generally better in large address space
1919 machines (Perl's malloc is mostly tuned for space).
1923 PERL_OBJECT has been completely removed.
1927 =head1 Security Vulnerability Closed
1929 (This change was already made in 5.7.0 but bears repeating here.)
1931 A potential security vulnerability in the optional suidperl component
1932 of Perl was identified in August 2000. suidperl is neither built nor
1933 installed by default. As of November 2001 the only known vulnerable
1934 platform is Linux, most likely all Linux distributions. CERT and
1935 various vendors and distributors have been alerted about the vulnerability.
1936 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
1937 for more information.
1939 The problem was caused by Perl trying to report a suspected security
1940 exploit attempt using an external program, /bin/mail. On Linux
1941 platforms the /bin/mail program had an undocumented feature which
1942 when combined with suidperl gave access to a root shell, resulting in
1943 a serious compromise instead of reporting the exploit attempt. If you
1944 don't have /bin/mail, or if you have 'safe setuid scripts', or if
1945 suidperl is not installed, you are safe.
1947 The exploit attempt reporting feature has been completely removed from
1948 Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
1949 from all the Perl 5.7 releases), so that particular vulnerability
1950 isn't there anymore. However, further security vulnerabilities are,
1951 unfortunately, always possible. The suidperl code is being reviewed
1952 and if deemed too risky to continue to be supported, it may be
1953 completely removed from future releases. In any case, suidperl should
1954 only be used by security experts who know exactly what they are doing
1955 and why they are using suidperl instead of some other solution such as
1956 sudo (see http://www.courtesan.com/sudo/).
1958 =head1 Selected Bug Fixes
1960 Numerous memory leaks and uninitialized memory accesses have been hunted down.
1961 Most importantly anonymous subs used to leak quite a bit.
1967 chop(@list) in list context returned the characters chopped in
1968 reverse order. This has been reversed to be in the right order.
1972 The order of DESTROYs has been made more predictable.
1976 mkdir() now ignores trailing slashes in the directory name,
1977 as mandated by POSIX.
1981 Attributes (like :shared) didn't work with our().
1985 The PERL5OPT environment variable (for passing command line arguments
1986 to Perl) didn't work for more than a single group of options.
1990 The tainting behaviour of sprintf() has been rationalized. It does
1991 not taint the result of floating point formats anymore, making the
1992 behaviour consistent with that of string interpolation.
1996 All but the first argument of the IO syswrite() method are now optional.
2000 Tie::ARRAY SPLICE method was broken.
2004 vec() now tries to work with characters <= 255 when possible, but it leaves
2005 higher character values in place. In that case, if vec() was used to modify
2006 the string, it is no longer considered to be utf8-encoded.
2010 The autouse pragma didn't work for Multi::Part::Function::Names.
2014 The behaviour of non-decimal but numeric string constants such as
2015 "0x23" was platform-dependent: in some platforms that was seen as 35,
2016 in some as 0, in some as a floating point number (don't ask). This
2017 was caused by Perl using the operating system libraries in a situation
2018 where the result of the string to number conversion is undefined: now
2019 Perl consistently handles such strings as zero in numeric contexts.
2023 L<dprofpp> -R didn't work.
2027 PERL5OPT with embedded spaces didn't work.
2031 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
2035 =head2 Platform Specific Changes and Fixes
2041 Some versions of glibc have a broken modfl(). This affects builds
2042 with C<-Duselongdouble>. This version of Perl detects this brokenness
2043 and has a workaround for it. The glibc release 2.2.2 is known to have
2044 fixed the modfl() bug.
2048 =head2 Platform Specific Changes and Fixes
2054 Linux previously had problems related to sockaddrlen when using
2055 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
2059 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
2069 Borland C++ v5.5 is now a supported compiler that can build Perl.
2070 However, the generated binaries continue to be incompatible with those
2071 generated by the other supported compilers (GCC and Visual C++).
2075 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
2076 Other bugs in chdir() and Cwd::cwd() have also been fixed.
2080 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
2084 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
2088 The makefiles now provide a single switch to bulk-enable all the features
2089 enabled in ActiveState ActivePerl (a popular binary distribution).
2095 Several new tests have been added, especially for the F<lib> subsection.
2097 The tests are now reported in a different order than in earlier Perls.
2098 (This happens because the test scripts from under t/lib have been moved
2099 to be closer to the library/extension they are testing.)
2101 =head1 New or Changed Diagnostics
2107 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
2108 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
2109 many people found the C<E<lt>E<lt>> to be too similar to here-document
2114 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
2115 using the C<"C"> format you will get an optional warning. Similarly
2116 for the C<"c"> format and a number less than -128 or more than 127.
2120 Certain regex modifiers such as C<(?o)> make sense only if applied to
2121 the entire regex. You will an optional warning if you try to do otherwise.
2125 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
2126 deprecated for a while. Now you will get an optional warning.
2130 =head1 Source Code Enhancements
2132 =head2 MAGIC constants
2134 The MAGIC constants (e.g. C<'P'>) have been macrofied
2135 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
2136 and maintainability.
2138 =head2 Better commented code
2140 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
2142 =head2 Regex pre-/post-compilation items matched up
2144 The regex compiler now maintains a structure that identifies nodes in
2145 the compiled bytecode with the corresponding syntactic features of the
2146 original regex expression. The information is attached to the new
2147 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
2148 complete information.
2152 The C code has been made much more C<gcc -Wall> clean. Some warning
2153 messages still remain, though, so if you are compiling with gcc you
2154 will see some warnings about dubious practices. The warnings are
2157 =head1 Known Problems
2159 Note that unlike other sections in this document (which describe
2160 changes since 5.7.0) this section is cumulative containing known
2161 problems for all the 5.7 releases.
2169 In AIX 4.2 Perl extensions that use C++ functions that use statics
2170 may have problems in that the statics are not getting initialized.
2171 In newer AIX releases this has been solved by linking Perl with
2172 the libC_r library, but unfortunately in AIX 4.2 the said library
2173 has an obscure bug where the various functions related to time
2174 (such as time() and gettimeofday()) return broken values, and
2175 therefore in AIX 4.2 Perl is not linked against the libC_r.
2179 vac 5.0.0.0 May Produce Buggy Code For Perl
2181 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
2182 resulting in few random tests failing, but when the failing tests
2183 are run by hand, they succeed. We suggest upgrading to at least
2184 vac version 5.0.1.0, that has been known to compile Perl correctly.
2185 "lslpp -L|grep vac.C" will tell you the vac version.
2189 =head2 Amiga Perl Invoking Mystery
2191 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
2192 works, but for example C<bin:perl -v> doesn't. The exact reason is
2193 known but the current suspect is the F<ixemul> library.
2195 =head2 lib/ftmp-security tests warn 'system possibly insecure'
2197 Don't panic. Read INSTALL 'make test' section instead.
2199 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
2201 The subtests 11 and 12 sometimes fail and sometimes work.
2203 =head2 HP-UX lib/io_multihomed Fails When LP64-Configured
2205 The lib/io_multihomed test may hang in HP-UX if Perl has been
2206 configured to be 64-bit. Because other 64-bit platforms do not hang in
2207 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2208 test attempts to create and connect to "multihomed" sockets (sockets
2209 which have multiple IP addresses).
2211 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
2213 If perl is configured with -Duse64bitall, the successful result of the
2214 subtest 10 of lib/posix may arrive before the successful result of the
2215 subtest 9, which confuses the test harness so much that it thinks the
2218 =head2 Linux With Sfio Fails op/misc Test 48
2224 OS/390 has rather many test failures but the situation is actually
2225 better than it was in 5.6.0, it's just that so many new modules and
2226 tests have been added.
2228 Failed Test Stat Wstat Total Fail Failed List of Failed
2229 -----------------------------------------------------------------------------
2230 ../ext/B/Deparse.t 14 1 7.14% 14
2231 ../ext/B/Showlex.t 1 1 100.00% 1
2232 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
2234 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
2235 ../ext/POSIX/POSIX.t 29 1 3.45% 14
2236 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
2237 ../lib/locale.t 129 33024 117 19 16.24% 99-117
2238 ../lib/warnings.t 434 1 0.23% 75
2239 ../lib/ExtUtils.t 27 1 3.70% 25
2240 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
2241 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
2242 ../lib/User/pwent.t 9 1 11.11% 4
2243 op/pat.t 660 6 0.91% 242-243 424-425
2245 op/split.t 0 9 ?? ?? % ??
2246 op/taint.t 174 3 1.72% 156 162 168
2247 op/tr.t 70 3 4.29% 50 58-59
2248 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
2250 =head2 op/sprintf tests 129 and 130
2252 The op/sprintf tests 129 and 130 are known to fail on some platforms.
2253 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
2254 The failing platforms do not comply with the ANSI C Standard, line
2255 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
2256 something other than "1" and "-1" when formatting 0.6 and -0.6 using
2257 the printf format "%.0f", most often they produce "0" and "-0".)
2259 =head2 Failure of Thread tests
2261 B<Note that support for 5.005-style threading remains experimental.>
2263 The following tests are known to fail due to fundamental problems in
2264 the 5.005 threading implementation. These are not new failures--Perl
2265 5.005_0x has the same bugs, but didn't have these tests.
2268 t/lib/thr5005.t 19-20
2276 ext/POSIX/sigaction subtests 6 and 13 may fail.
2280 lib/ExtUtils may spuriously claim that subtest 28 failed,
2281 which is interesting since the test only has 27 tests.
2285 Numerous numerical test failures
2287 op/numconvert 209,210,217,218
2289 ext/Time/HiRes/HiRes 9
2290 lib/Math/BigInt/t/bigintpm 1145
2293 These tests fail because of yet unresolved floating point inaccuracies.
2299 There are a few known test failures, see L<perluts>.
2303 Rather many tests are failing in VMS but that actually more tests
2304 succeed in VMS than they used to, it's just that there are many,
2305 many more tests than there used to be.
2307 Here are the known failures from some compiler/platform combinations.
2309 DEC C V5.3-006 on OpenVMS VAX V6.2
2311 [-.ext.list.util.t]tainted..............FAILED on test 3
2312 [-.ext.posix]sigaction..................FAILED on test 7
2313 [-.ext.time.hires]hires.................FAILED on test 14
2314 [-.lib.file.find]taint..................FAILED on test 17
2315 [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
2316 [-.lib.test.simple.t]exit...............FAILED on test 1
2317 [.lib]vmsish............................FAILED on test 13
2318 [.op]sprintf............................FAILED on test 12
2319 Failed 8/399 tests, 91.23% okay.
2321 DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and
2322 Compaq C V6.2-008 on OpenVMS Alpha V7.1
2324 [-.ext.list.util.t]tainted..............FAILED on test 3
2325 [-.lib.file.find]taint..................FAILED on test 17
2326 [-.lib.test.simple.t]exit...............FAILED on test 1
2327 [.lib]vmsish............................FAILED on test 13
2328 Failed 4/399 tests, 92.48% okay.
2330 Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
2332 [-.ext.b]showlex........................FAILED on test 1
2333 [-.ext.list.util.t]tainted..............FAILED on test 3
2334 [-.lib.file.find]taint..................FAILED on test 17
2335 [-.lib.test.simple.t]exit...............FAILED on test 1
2336 [.lib]vmsish............................FAILED on test 13
2337 [.op]misc...............................FAILED on test 49
2338 Failed 6/401 tests, 92.77% okay.
2342 In multi-CPU boxes there are some problems with the I/O buffering:
2343 some output may appear twice.
2345 =head2 Localising a Tied Variable Leaks Memory
2348 tie my %tie_hash => 'Tie::StdHash';
2352 local($tie_hash{Foo}) = 1; # leaks
2354 Code like the above is known to leak memory every time the local()
2357 =head2 Self-tying of Arrays and Hashes Is Forbidden
2359 Self-tying of arrays and hashes is broken in rather deep and
2360 hard-to-fix ways. As a stop-gap measure to avoid people from getting
2361 frustrated at the mysterious results (core dumps, most often) it is
2362 for now forbidden (you will get a fatal error even from an attempt).
2364 =head2 Variable Attributes are not Currently Usable for Tieing
2366 This limitation will hopefully be fixed in future. (Subroutine
2367 attributes work fine for tieing, see L<Attribute::Handlers>).
2369 =head2 Building Extensions Can Fail Because Of Largefiles
2371 Some extensions like mod_perl are known to have issues with
2372 `largefiles', a change brought by Perl 5.6.0 in which file offsets
2373 default to 64 bits wide, where supported. Modules may fail to compile
2374 at all or compile and work incorrectly. Currently there is no good
2375 solution for the problem, but Configure now provides appropriate
2376 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
2377 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
2378 having problems can try configuring themselves without the
2379 largefileness. This is admittedly not a clean solution, and the
2380 solution may not even work at all. One potential failure is whether
2381 one can (or, if one can, whether it's a good idea) link together at
2382 all binaries with different ideas about file offsets, all this is
2385 =head2 The Compiler Suite Is Still Experimental
2387 The compiler suite is slowly getting better but is nowhere near
2390 =head2 The Long Double Support is Still Experimental
2392 The ability to configure Perl's numbers to use "long doubles",
2393 floating point numbers of hopefully better accuracy, is still
2394 experimental. The implementations of long doubles are not yet
2395 widespread and the existing implementations are not quite mature
2396 or standardised, therefore trying to support them is a rare
2397 and moving target. The gain of more precision may also be offset
2398 by slowdown in computations (more bits to move around, and the
2399 operations are more likely to be executed by less optimised
2402 =head1 Reporting Bugs
2404 If you find what you think is a bug, you might check the articles
2405 recently posted to the comp.lang.perl.misc newsgroup and the perl
2406 bug database at http://bugs.perl.org. There may also be
2407 information at http://www.perl.com/perl/, the Perl Home Page.
2409 If you believe you have an unreported bug, please run the B<perlbug>
2410 program included with your release. Be sure to trim your bug down
2411 to a tiny but sufficient test case. Your bug report, along with the
2412 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2413 analysed by the Perl porting team.
2417 The F<Changes> file for exhaustive details on what changed.
2419 The F<INSTALL> file for how to build Perl.
2421 The F<README> file for general stuff.
2423 The F<Artistic> and F<Copying> files for copyright information.
2427 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.