X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperldelta.pod;h=9ac2964b02281302582a169000f082dc466d3ecd;hb=b851fbc1add6c3d9fa6158884279133c311a3efc;hp=2a4ad88cbe3bdae3e3aa9f3b559b214dfa58fc54;hpb=c1899e02bd58ea340a8d89dc821ccba4502a63a7;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perldelta.pod b/pod/perldelta.pod index 2a4ad88..9ac2964 100644 --- a/pod/perldelta.pod +++ b/pod/perldelta.pod @@ -1,58 +1,2606 @@ =head1 NAME -perldelta - what's new for perl v5.8.0 +perldelta - what is new for perl v5.8.0 =head1 DESCRIPTION -This document describes differences between the 5.6 release and this one. +This document describes differences between the 5.6.0 release +and the 5.8.0 release. + +Many of the bug fixes in 5.8.0 were already seen in the 5.6.1 +maintenance release since the two releases were kept closely +coordinated. + +If you are upgrading from Perl 5.005_03, you might also want +to read L. + +=head1 Highlights In 5.8.0 + +=over 4 + +=item * + +Better Unicode support + +=item * + +New Thread Implementation + +=item * + +Many New Modules + +=item * + +Better Numeric Accuracy + +=item * + +Safe Signals + +=item * + +More Extensive Regression Testing + +=back + +=head1 Incompatible Changes + +=head2 64-bit platforms and malloc + +If your pointers are 64 bits wide, the Perl malloc is no longer being +used because it does not work well with 8-byte pointers. Also, +usually the system mallocs on such platforms are much better optimized +for such large memory models than the Perl malloc. Some memory-hungry +Perl applications like the PDL don't work well with Perl's malloc. +Finally, other applications than Perl (like modperl) tend to prefer +the system malloc. Such platforms include Alpha and 64-bit HPPA, +MIPS, PPC, and Sparc. + +=head2 AIX Dynaloading + +The AIX dynaloading now uses in AIX releases 4.3 and newer the native +dlopen interface of AIX instead of the old emulated interface. This +change will probably break backward compatibility with compiled +modules. The change was made to make Perl more compliant with other +applications like modperl which are using the AIX native interface. + +=head2 Attributes for C variables now handled at run-time. + +The C syntax now applies variable attributes at +run-time. (Subroutine and C variables still get attributes applied +at compile-time.) See L for additional details. In particular, +however, this allows variable attributes to be useful for C interfaces, +which was a deficiency of earlier releases. Note that the new semantics +doesn't work with the Attribute::Handlers module (as of version 0.76). + +=head2 Socket Extension Dynamic in VMS + +The Socket extension is now dynamically loaded instead of being +statically built in. This may or may not be a problem with ancient +TCP/IP stacks of VMS: we do not know since we weren't able to test +Perl in such configurations. + +=head2 IEEE-format Floating Point Default on OpenVMS Alpha + +Perl now uses IEEE format (T_FLOAT) as the default internal floating +point format on OpenVMS Alpha, potentially breaking binary compatibility +with external libraries or existing data. G_FLOAT is still available as +a configuration option. The default on VAX (D_FLOAT) has not changed. + +=head2 Different Definition of the Unicode Character Classes \p{In...} + +As suggested by the Unicode consortium, the Unicode character classes +now prefer I as opposed to I (as defined by Unicode); +in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression +constructs are used. This has changed the definition of some of those +character classes. + +The difference between scripts and blocks is that scripts are the +glyphs used by a language or a group of languages, while the blocks +are more artificial groupings of 256 characters based on the Unicode +numbering. + +In general this change results in more inclusive Unicode character +classes, but changes to the other direction also do take place: +for example while the script C includes all the Latin +characters and their various diacritic-adorned versions, it +does not include the various punctuation or digits (since they +are not solely C). + +Changes in the character class semantics may have happened if a script +and a block happen to have the same name, for example C. +In such cases the script wins and C<\p{InHebrew}> now means the script +definition of Hebrew. The block definition in still available, +though, by appending C to the name: C<\p{InHebrewBlock}> means +what C<\p{InHebrew}> meant in perl 5.6.0. For the full list +of affected character classes, see L. + +=head2 Perl Parser Stress Tested + +The Perl parser has been stress tested using both random input and +Markov chain input and the few found crashes and lockups have been +fixed. + +=head2 REF(...) Instead Of SCALAR(...) + +A reference to a reference now stringifies as "REF(0x81485ec)" instead +of "SCALAR(0x81485ec)" in order to be more consistent with the return +value of ref(). + +=head2 Deprecations + +=over 4 + +=item * + +The semantics of bless(REF, REF) were unclear and until someone proves +it to make some sense, it is forbidden. + +=item * + +The obsolete chat2 library that should never have been allowed +to escape the laboratory has been decommissioned. + +=item * + +The very dusty examples in the eg/ directory have been removed. +Suggestions for new shiny examples welcome but the main issue is that +the examples need to be documented, tested and (most importantly) +maintained. + +=item * + +The (bogus) escape sequences \8 and \9 now give an optional warning +("Unrecognized escape passed through"). There is no need to \-escape +any C<\w> character. + +=item * + +The list of filenames from glob() (or <...>) is now by default sorted +alphabetically to be csh-compliant (which is what happened before +in most UNIX platforms). (bsd_glob() does still sort platform +natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) + +=item * + +Spurious syntax errors generated in certain situations, when glob() +caused File::Glob to be loaded for the first time, have been fixed. + +=item * + +Although "you shouldn't do that", it was possible to write code that +depends on Perl's hashed key order (Data::Dumper does this). The new +algorithm "One-at-a-Time" produces a different hashed key order. +More details are in L. + +=item * + +lstat(FILEHANDLE) now gives a warning because the operation makes no sense. +In future releases this may become a fatal error. + +=item * + +The C syntax (C without an argument) has been +deprecated. Its semantics were never that clear and its +implementation even less so. If you have used that feature to +disallow all but fully qualified variables, C instead. + +=item * + +The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still +recognised but now cause fatal errors. The previous behaviour of +ignoring them by default and warning if requested was unacceptable +since it, in a way, falsely promised that the features could be used. + +=item * + +The current user-visible implementation of pseudo-hashes (the weird +use of the first array element) is deprecated starting from Perl 5.8.0 +and will be removed in Perl 5.10.0, and the feature will be +implemented differently. Not only is the current interface rather +ugly, but the current implementation slows down normal array and hash +use quite noticeably. The C pragma interface will remain +available. + +=item * + +The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated. + +=item * + +After years of trying the suidperl is considered to be too complex to +ever be considered truly secure. The suidperl functionality is likely +to be removed in a future release. + +=item * + +The long deprecated uppercase aliases for the string comparison +operators (EQ, NE, LT, LE, GE, GT) have now been removed. + +=item * + +The tr///C and tr///U features have been removed and will not return; +the interface was a mistake. Sorry about that. For similar +functionality, see pack('U0', ...) and pack('C0', ...). + +=back =head1 Core Enhancements -=head1 Modules and Pragmata +=head2 PerlIO is Now The Default + +=over 4 + +=item * + +IO is now by default done via PerlIO rather than system's "stdio". +PerlIO allows "layers" to be "pushed" onto a file handle to alter the +handle's behaviour. Layers can be specified at open time via 3-arg +form of open: + + open($fh,'>:crlf :utf8', $path) || ... + +or on already opened handles via extended C: + + binmode($fh,':encoding(iso-8859-7)'); + +The built-in layers are: unix (low level read/write), stdio (as in +previous Perls), perlio (re-implementation of stdio buffering in a +portable manner), crlf (does CRLF <=> "\n" translation as on Win32, +but available on any platform). A mmap layer may be available if +platform supports it (mostly UNIXes). + +Layers to be applied by default may be specified via the 'open' pragma. + +See L for the effects +of PerlIO on your architecture name. + +=item * + +File handles can be marked as accepting Perl's internal encoding of Unicode +(UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" : + + open($fh,">:utf8","Uni.txt"); + +Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named +for you since it's not UTF-8 what you will be getting but instead +UTF-EBCDIC. See L, L, and +http://www.unicode.org/unicode/reports/tr16/ for more information. +In future releases this naming may change. + +=item * + +File handles can translate character encodings from/to Perl's internal +Unicode form on read/write via the ":encoding()" layer. + +=item * + +File handles can be opened to "in memory" files held in Perl scalars via: + + open($fh,'>', \$variable) || ... + +=item * + +Anonymous temporary files are available without need to +'use FileHandle' or other module via + + open($fh,"+>", undef) || ... + +That is a literal undef, not an undefined value. + +=item * + +The list form of C is now implemented for pipes (at least on UNIX): + + open($fh,"-|", 'cat', '/etc/motd') + +creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in +the child process. + +=back + +=head2 Safe Signals + +Perl used to be fragile in that signals arriving at inopportune moments +could corrupt Perl's internal state. Now Perl postpones handling of +signals until it's safe (between opcodes). + +This change may have surprising side effects because signals no more +interrupt Perl instantly. Perl will now first finish whatever it was +doing, like finishing an internal operation (like sort()) or an +external operation (like an I/O operation), and only then look at any +arrived signals (and before starting the next operation). No more corrupt +internal state since the current operation is always finished first, +but the signal may take more time to get heard. + +=head2 Unicode Overhaul + +Unicode in general should be now much more usable than in Perl 5.6.0 +(or even in 5.6.1). Unicode can be used in hash keys, Unicode in +regular expressions should work now, Unicode in tr/// should work now, +Unicode in I/O should work now. + +=over 4 + +=item * + +The Unicode Character Database coming with Perl has been upgraded +to Unicode 3.1.1. For more information, see http://www.unicode.org/. + +=item * + +For developers interested in enhancing Perl's Unicode capabilities: +almost all the UCD files are included with the Perl distribution in +the lib/unicore subdirectory. The most notable omission, for space +considerations, is the Unihan database. + +=item * + +The Unicode character classes \p{Blank} and \p{SpacePerl} have been +added. "Blank" is like C isblank(), that is, it contains only +"horizontal whitespace" (the space character is, the newline isn't), +and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space} +isn't, since that includes the vertical tabulator character, whereas +C<\s> doesn't.) + +=back + +=head2 Understanding of Numbers + +In general a lot of fixing has happened in the area of Perl's +understanding of numbers, both integer and floating point. Since in +many systems the standard number parsing functions like C +and C seem to have bugs, Perl tries to work around their +deficiencies. This results hopefully in more accurate numbers. + +Perl now tries internally to use integer values in numeric conversions +and basic arithmetics (+ - * /) if the arguments are integers, and +tries also to keep the results stored internally as integers. +This change leads to often slightly faster and always less lossy +arithmetics. (Previously Perl always preferred floating point numbers +in its math.) + +=head2 Miscellaneous Enhancements + +=over 4 + +=item * + +AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute +to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value. + +=item * + +C now works (previously one couldn't pass +in multiple arguments.) + +=item * + +END blocks are now run even if you exit/die in a BEGIN block. +Internally, the execution of END blocks is now controlled by +PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new +behaviour for Perl embedders. This will default in 5.10. See +L. + +=item * + +Formats now support zero-padded decimal fields. + +=item * + +Lvalue subroutines can now return C in list context. +However, the lvalue subroutine feature still remains experimental. + +=item * + +A new special regular expression variable has been introduced: +C<$^N>, which contains the most-recently closed group (submatch). + +=item * + +C now works even if there is no "sub unimport" in the Module. + +=item * + +The numerical comparison operators return C if either operand +is a NaN. Previously the behaviour was unspecified. + +=item * + +The following builtin functions are now overridable: each(), keys(), +pop(), push(), shift(), splice(), unshift(). + +=item * + +C can now be used to force a string to UTF8. + +=item * + +my __PACKAGE__ $obj now works. + +=item * + +The printf() and sprintf() now support parameter reordering using the +C<%\d+\$> and C<*\d+\$> syntaxes. For example + + print "%2\$s %1\$s\n", "foo", "bar"; + +will print "bar foo\n". This feature helps in writing +internationalised software, and in general when the order +of the parameters can vary. + +=item * + +prototype(\&) is now available. + +=item * + +prototype(\[$@%&]) is now available to implicitly create references +(useful for example if you want to emulate the tie() interface). + +=item * + +untie() will now call an UNTIE() hook if it exists. See L +for details. + +=item * + +L now supports C to change the +file timestamps to the current time. + +=item * + +The rules for allowing underscores (underbars) in numeric constants +have been relaxed and simplified: now you can have an underscore +simply B. + +=back + +=head1 Modules and Pragmata + +=head2 New Modules and Pragmata + +=over 4 + +=item * + +C allows a class to define attribute handlers. + + package MyPack; + use Attribute::Handlers; + sub Wolf :ATTR(SCALAR) { print "howl!\n" } + + # later, in some package using or inheriting from MyPack... + + my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called + +Both variables and routines can have attribute handlers. Handlers can +be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the +exact compilation phase (BEGIN, CHECK, INIT, or END). + +=item * + +B is a new compiler backend for walking the Perl syntax +tree, printing concise info about ops, from Stephen McCamant. The +output is highly customisable. See L. + +=item * + +C for reporting the search path for a class's ISA tree, +by Sean Burke, has been added. See L. + +=item * + +C has now a split personality: if possible, an XS extension is +used, (this will hopefully be faster, more secure, and more robust) +but if not possible, the familiar Perl implementation is used. + +=item * + +C, originally from Kenneth Albanowski and now +maintained by Paul Marquess, has been added. It is primarily used +by C to enhance portability of of XS modules between different +versions of Perl. + +=item * + +C, frontend module for calculating digests (checksums), from +Gisle Aas, has been added. See L. + +=item * + +C for calculating MD5 digests (checksums) as defined in +RFC 1321, from Gisle Aas, has been added. See L. + + use Digest::MD5 'md5_hex'; + + $digest = md5_hex("Thirsty Camel"); + + print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1 + +NOTE: the C backward compatibility module is deliberately not +included since its further use is discouraged. + +=item * + +C, by Nick Ing-Simmons, provides a mechanism to translate +between different character encodings. Support for Unicode, +ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are +compiled in to the module. Several other encodings (like Japanese, +Chinese, and MacIntosh encodings) are included and will be loaded at +runtime. See L. + +Any encoding supported by Encode module is also available to the +":encoding()" layer if PerlIO is used. + +=item * + +C can be use to query locale information. +See L. + +=item * + +C has functions for dealing with RFC3066-style +language tags, by Sean Burke. See L. + +=item * + +C is a new tool for extension writers for +generating XS code to import C header constants, by Nicholas Clark. +See L. + +=item * + +C is an easy-to-use frontend to Filter::Util::Call, +from Damian Conway. See L. + + # in MyFilter.pm: + + package MyFilter; + + use Filter::Simple sub { + while (my ($from, $to) = splice @_, 0, 2) { + s/$from/$to/g; + } + }; + + 1; + + # in user's code: + + use MyFilter qr/red/ => 'green'; + + print "red\n"; # this code is filtered, will print "green\n" + print "bored\n"; # this code is filtered, will print "bogreen\n" + + no MyFilter; + + print "red\n"; # this code is not filtered, will print "red\n" + +=item * + +C allows one to create temporary files and directories in +an easy, portable, and secure way, by Tim Jenness. See L. + +=item * + +C provides you with the framework to write +I in Perl, from Paul Marquess. For most uses the +frontend Filter::Simple is to be preferred. See L. + +=item * + +L is a collection of perl5 modules related to network +programming, from Graham Barr. See L, L, +L, L, L, and L. + +Perl installation leaves libnet unconfigured, use F to configure. + +=item * + +C is a selection of general-utility list subroutines, like +sum(), min(), first(), and shuffle(), by Graham Barr. See L. + +=item * + +C, C, C, and +C, from Neil Bowers, have been added. They provide the +codes for various locale standards, such as "fr" for France, "usd" for +US Dollar, and "jp" for Japanese. + + use Locale::Country; + + $country = code2country('jp'); # $country gets 'Japan' + $code = country2code('Norway'); # $code gets 'no' + +See L, L, L, +and L. + +=item * + +C is localization framework from Sean Burke. See +L, and L. The latter is an +article about software localization, originally published in The Perl +Journal #13, republished here with kind permission. + +=item * + +C can make your functions faster by trading space for time, +from Mark-Jason Dominus. See L. + +=item * + +C allows you to encode data in base64, from Gisle Aas, +as defined in RFC 2045 - I. + + use MIME::Base64; + + $encoded = encode_base64('Aladdin:open sesame'); + $decoded = decode_base64($encoded); + + print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ==" + +See L. + +=item * + +C allows you to encode data in quoted-printable +encoding, as defined in RFC 2045 - I, from Gisle Aas. + + use MIME::QuotedPrint; + + $encoded = encode_qp("Smiley in Unicode: \x{263a}"); + $decoded = decode_qp($encoded); + + print $encoded, "\n"; # "Smiley in Unicode: =263A" + +MIME::QuotedPrint has been enhanced to provide the basic methods +necessary to use it with PerlIO::Via as in : + + use MIME::QuotedPrint; + open($fh,">Via(MIME::QuotedPrint)",$path); + +See L. + +=item * + +C is pseudo-class for method redispatch, from Damian Conway. +See L. + +=item * + +C is a new pragma for setting the default I/O disciplines +for open(). + +=item * + +C provides the implementation of IO to "in memory" +Perl scalars as discussed above, from Nick Ing-Simmons. It also +serves as an example of a loadable PerlIO layer. Other future +possibilities include PerlIO::Array and PerlIO::Code. +See L. + +=item * + +C acts as a PerlIO layer and wraps PerlIO layer +functionality provided by a class (typically implemented in perl +code), from Nick Ing-Simmons. + + use MIME::QuotedPrint; + open($fh,">Via(MIME::QuotedPrint)",$path); + +This will automatically convert everything output to C<$fh> +to Quoted-Printable. See L. + +=item * + +C, by Russ Allbery, has been added, +to parse LZ<><> links in pods as described in the new +perlpodspec. + +=item * + +C, by Joe Smith, has been added. +It converts POD data to formatted overstrike text. +See L. + +=item * + +C is a selection of general-utility scalar subroutines, +like blessed(), reftype(), and tainted(). See L. + +=item * + +C is a new pragma for controlling the behaviour of sort(). + +=item * + +C gives persistence to Perl data structures by allowing the +storage and retrieval of Perl data to and from files in a fast and +compact binary format, from Raphael Manfredi. See L. + +=item * + +C, from Damian Conway, has been added. Just by saying + + use Switch; + +you have C and C available in Perl. + + use Switch; + + switch ($val) { + + case 1 { print "number 1" } + case "a" { print "string a" } + case [1..10,42] { print "number in list" } + case (@array) { print "number in list" } + case /\w+/ { print "pattern" } + case qr/\w+/ { print "pattern" } + case (%hash) { print "entry in hash" } + case (\%hash) { print "entry in hash" } + case (\&sub) { print "arg to subroutine" } + else { print "previous case not true" } + } + +See L. + +=item * + +C is yet another framework for writing test scripts, +more extensive than Test::Simple, by Michael Schwern. See L. + +=item * + +C has basic utilities for writing tests, by Michael +Schwern. See L. + +=item * + +C has been added, for extracting delimited text +sequences from strings, from Damian Conway. + + use Text::Balanced 'extract_delimited'; + + ($a, $b) = extract_delimited("'never say never', he never said", "'", ''); + +$a will be "'never say never'", $b will be ', he never said'. + +In addition to extract_delimited() there are also extract_bracketed(), +extract_quotelike(), extract_codeblock(), extract_variable(), +extract_tagged(), extract_multiple(), gen_delimited_pat(), and +gen_extract_tagged(). With these you can implement rather advanced +parsing algorithms. See L. + +=item * + +C is an interface to interpreter threads, by Arthur Bergman. +Interpreter threads (ithreads) is the new thread model introduced in +Perl 5.6 but only available as an internal interface for extension +writers (and for Win32 Perl for C emulation). See L. + +=item * + +C allows data sharing for interpreter threads, from +Arthur Bergman. In the ithreads model any data sharing between +threads must be explicit, as opposed to the old 5.005 thread model +where data sharing was implicit. See L. + +=item * + +C, by Edward Avis, allows storing hash +references (unlike the standard Tie::RefHash) The module is contained +within Tie::RefHash, see L. + +=item * + +C provides high resolution timing (ualarm, usleep, +and gettimeofday), from Douglas E. Wegscheid. See L. + +=item * + +C offers a querying interface to the Unicode Character +Database. See L. + +=item * + +C implements the UCA (Unicode Collation Algorithm) +for sorting Unicode strings, by SADAHIRO Tomoyuki. See L. + +=item * + +C implements the various Unicode normalization +forms, by SADAHIRO Tomoyuki. See L. + +=item * + +C, by Tim Jenness, is a test extension that exercises XS +typemaps. Nothing gets installed but for extension writers the code +is worth studying. + +=back + +=head2 Updated And Improved Modules and Pragmata + +=over 4 + +=item * + +The following independently supported modules have been updated to the +newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp, +Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle +(Pod::Man, Pod::Text), Pod::LaTeX, Pod::Parser, Storable, +Term::ANSIColor, Test, Text-Tabs+Wrap. + +=item * + +The attributes::reftype() now works on tied arguments. + +=item * + +AutoLoader can now be disabled with C. + +=item * + +B::Deparse has been significantly enhanced. It now can deparse almost +all of the standard test suite (so that the tests still succeed). +There is a make target "test.deparse" for trying this out. + +=item * + +Class::Struct can now define the classes in compile time. + +=item * + +Class::Struct now assigns the array/hash element if the accessor +is called with an array/hash element as the B argument. + +=item * + +Data::Dumper has now an option to sort hashes. + +=item * + +Data::Dumper has now an option to dump code references +using B::Deparse. + +=item * + +DB_File now supports newer Berkeley DB versions, among +other improvements. + +=item * + +The English module can now be used without the infamous performance +hit by saying + + use English '-no_performance_hit'; + +(Assuming, of course, that one doesn't need the troublesome variables +C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and +C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>. + +=item * + +Fcntl, Socket, and Sys::Syslog have been rewritten to use the +new-style constant dispatch section (see L). +This means that they will be more robust and hopefully faster. + +=item * + +File::Find now chdir()s correctly when chasing symbolic links. + +=item * + +File::Find now has pre- and post-processing callbacks. It also +correctly changes directories when chasing symbolic links. Callbacks +(naughtily) exiting with "next;" instead of "return;" now work. + +=item * + +File::Find is now (again) reentrant. It also has been made +more portable. + +=item * + +File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid +prototype mismatch with CORE::glob(). + +=item * + +File::Glob now supports C constant to limit the size of +the returned list of filenames. + +=item * + +Devel::Peek now has an interface for the Perl memory statistics +(this works only if you are using perl's malloc, and if you have +compiled with debugging). + +=item * + +IPC::Open3 now allows the use of numeric file descriptors. + +=item * + +IO::Socket has now atmark() method, which returns true if the socket +is positioned at the out-of-band mark. The method is also exportable +as a sockatmark() function. + +=item * + +IO::Socket::INET has support for ReusePort option (if your platform +supports it). The Reuse option now has an alias, ReuseAddr. For clarity +you may want to prefer ReuseAddr. + +=item * + +IO::Socket::INET now supports C of zero (usually meaning +that the operating system will make one up.) + +=item * + +use lib now works identically to @INC. Removing directories +with 'no lib' now works. + +=item * + +Math::BigFloat and Math::BigInt have undergone a full rewrite. +They are now magnitudes faster, and they support various +bignum libraries such as GMP and PARI as their backends. + +=item * + +Math::Complex handles inf, NaN etc., better. + +=item * + +Net::Ping has been enhanced. There is now "external" protocol which +uses Net::Ping::External module which runs external ping(1) and parses +the output. A version of Net::Ping::External is available in CPAN. + +=item * + +POSIX::sigaction() is now much more flexible and robust. +You can now install coderef handlers, 'DEFAULT', and 'IGNORE' +handlers, installing new handlers was not atomic. + +=item * + +In Safe the C<%INC> now localised in a Safe compartment so that +use/require work. + +=item * + +In SDBM_File on dosish platforms, some keys went missing because of +lack of support for files with "holes". A workaround for the problem +has been added. + +=item * + +In Search::Dict one can now have a pre-processing hook for the +lines being searched. + +=item * + +The Shell module now has an OO interface. + +=item * + +The Test module has been significantly enhanced. + +=item * + +The vars pragma now supports declaring fully qualified variables. +(Something that C does not and will not support.) + +=item * + +The utf8:: name space (as in the pragma) provides various +Perl-callable functions to provide low level access to Perl's +internal Unicode representation. At the moment only length() +has been implemented. + +=back + +=head1 Utility Changes + +=over 4 + +=item * + +Emacs perl mode (emacs/cperl-mode.el) has been updated to version +4.31. + +=item * + +F is now much faster. + +=item * + +C now supports C trigraphs. + +=item * + +C now produces a template README. + +=item * + +C now uses C for better portability between +different versions of Perl. + +=item * + +C uses the new L module which will affect +newly created extensions that define constants. Since the new code is +more correct (if you have two constants where the first one is a +prefix of the second one, the first constant B gets defined), +less lossy (it uses integers for integer constant, as opposed to the +old code that used floating point numbers even for integer constants), +and slightly faster, you might want to consider regenerating your +extension code (the new scheme makes regenerating easy). +L now also supports C trigraphs. + +=item * + +C has been added to configure the libnet. + +=item * + +C is now much more robust. It also sends the bug report to +perl.org, not perl.com. + +=item * + +C has been rewritten and its user interface (that is, +command line) is much more like that of the UNIX C compiler, cc. +(The perlbc tools has been removed. Use C instead.) + +=item * + +C is a new Installation Verification Procedure utility +for running any time after installing Perl. + +=item * + +C now allows specifying a cache directory. + +=item * + +C has been completely rewritten in Perl. (It is in fact a full +implementation of sed in Perl: you can use the sed functionality by +using the C utility.) + +=item * + +C now understands POD documentation embedded in the *.xs files. + +=item * + +C now supports OUT keyword. + +=back + +=head1 New Documentation + +=over 4 + +=item * + +perl56delta details the changes between the 5.005 release and the +5.6.0 release. + +=item * + +perlclib documents the internal replacements for standard C library +functions. (Interesting only for extension writers and Perl core +hackers.) + +=item * + +perldebtut is a Perl debugging tutorial. + +=item * + +perlebcdic contains considerations for running Perl on EBCDIC platforms. + +=item * + +perlintro is a gentle introduction to Perl. + +=item * + +perliol documents the internals of PerlIO with layers. + +=item * + +perlmodstyle is a style guide for writing modules. + +=item * + +perlnewmod tells about writing and submitting a new module. + +=item * + +perlpacktut is a pack() tutorial. + +=item * + +perlpod has been rewritten to be clearer and to record the best +practices gathered over the years. + +=item * + +perlpodspec is a more formal specification of the pod format, +mainly of interest for writers of pod applications, not to +people writing in pod. + +=item * + +perlretut is a regular expression tutorial. + +=item * + +perlrequick is a regular expressions quick-start guide. +Yes, much quicker than perlretut. + +=item * + +perltodo has been updated. + +=item * + +perltootc has been renamed as perltooc (to not to conflict +with perltoot in filesystems restricted to "8.3" names) + +=item * + +perluniintro is an introduction to using Unicode in Perl +(perlunicode is more of a reference) + +=item * + +perlutil explains the command line utilities packaged with the Perl +distribution. + +=back + +The following platform-specific documents are available before +the installation as README.I, and after the installation +as perlI: + + perlaix perlamiga perlapollo perlbeos perlbs2000 + perlce perlcygwin perldgux perldos perlepoc perlhpux + perlhurd perlmachten perlmacos perlmint perlmpeix + perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris + perltru64 perluts perlvmesa perlvms perlvos perlwin32 + +=over 4 + +=item * + +The documentation for the POSIX-BC platform is called "BS2000", to avoid +confusion with the Perl POSIX module. + +=item * + +The documentation for the WinCE platform is called "CE", to avoid +confusion with the perlwin32 documentation on 8.3-restricted filesystems. + +=back + +=head1 Performance Enhancements + +=over 4 + +=item * + +map() could get pathologically slow when the result list it generates +is larger than the source list. The performance has been improved for +common scenarios. + +=item * + +sort() has been changed to use primarily mergesort internally as +opposed to the earlier quicksort. For very small lists this may +result in slightly slower sorting times, but in general the speedup +should be at least 20%. Additional bonuses are that the worst case +behaviour of sort() is now better (in computer science terms it now +runs in time O(N log N), as opposed to quicksort's Theta(N**2) +worst-case run time behaviour), and that sort() is now stable +(meaning that elements with identical keys will stay ordered as they +were before the sort). See the C pragma for information. + +The story in more detail: suppose you want to serve yourself a little +slice of Pi. + + @digits = ( 3,1,4,1,5,9 ); + +A numerical sort of the digits will yield (1,1,3,4,5,9), as expected. +Which C<1> comes first is hard to know, since one C<1> looks pretty +much like any other. You can regard this as totally trivial, +or somewhat profound. However, if you just want to sort the even +digits ahead of the odd ones, then what will + + sort { ($a % 2) <=> ($b % 2) } @digits; + +yield? The only even digit, C<4>, will come first. But how about +the odd numbers, which all compare equal? With the quicksort algorithm +used to implement Perl 5.6 and earlier, the order of ties is left up +to the sort. So, as you add more and more digits of Pi, the order +in which the sorted even and odd digits appear will change. +and, for sufficiently large slices of Pi, the quicksort algorithm +in Perl 5.8 won't return the same results even if reinvoked with the +same input. The justification for this rests with quicksort's +worst case behavior. If you run + + sort { $a <=> $b } ( 1 .. $N , 1 .. $N ); + +(something you might approximate if you wanted to merge two sorted +arrays using sort), doubling $N doesn't just double the quicksort time, +it I it. Quicksort has a worst case run time that can +grow like N**2, so-called I behaviour, and it can happen +on patterns that may well arise in normal use. You won't notice this +for small arrays, but you I notice it with larger arrays, +and you may not live long enough for the sort to complete on arrays +of a million elements. So the 5.8 quicksort scrambles large arrays +before sorting them, as a statistical defence against quadratic behaviour. +But that means if you sort the same large array twice, ties may be +broken in different ways. + +Because of the unpredictability of tie-breaking order, and the quadratic +worst-case behaviour, quicksort was I replaced completely with +a stable mergesort. I means that ties are broken to preserve +the original order of appearance in the input array. So + + sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9); + +will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers +appear in the output in the same order they appeared in the input. +Mergesort has worst case O(NlogN) behaviour, the best value +attainable. And, ironically, this mergesort does particularly +well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N) +in O(N) time. But quicksort was rescued at the last moment because +it is faster than mergesort on certain inputs and platforms. +For example, if you really I care about the order of even +and odd digits, quicksort will run in O(N) time; it's very good +at sorting many repetitions of a small number of distinct elements. +The quicksort divide and conquer strategy works well on platforms +with relatively small, very fast, caches. Eventually, the problem gets +whittled down to one that fits in the cache, from which point it +benefits from the increased memory speed. + +Quicksort was rescued by implementing a sort pragma to control aspects +of the sort. The B subpragma forces stable behaviour, +regardless of algorithm. The B<_quicksort> and B<_mergesort> +subpragmas are heavy-handed ways to select the underlying implementation. +The leading C<_> is a reminder that these subpragmas may not survive +beyond 5.8. More appropriate mechanisms for selecting the implementation +exist, but they wouldn't have arrived in time to save quicksort. + +=item * + +Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm +(http://burtleburtle.net/bob/hash/doobs.html). This algorithm is +reasonably fast while producing a much better spread of values than +the old hashing algorithm (originally by Chris Torek, later tweaked by +Ilya Zakharevich). Hash values output from the algorithm on a hash of +all 3-char printable ASCII keys comes much closer to passing the +DIEHARD random number generation tests. According to perlbench, this +change has not affected the overall speed of Perl. + +=item * + +unshift() should now be noticeably faster. + +=back + +=head1 Installation and Configuration Improvements + +=head2 Generic Improvements + +=over 4 + +=item * + +INSTALL now explains how you can configure Perl to use 64-bit +integers even on non-64-bit platforms. + +=item * + +Policy.sh policy change: if you are reusing a Policy.sh file +(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old +Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of +them will now be changed to the new prefix, /foo/bar. (Previously +only $prefix changed.) If you do not like this new behaviour, +specify prefix, siteprefix, and vendorprefix explicitly. + +=item * + +A new optional location for Perl libraries, otherlibdirs, is available. +It can be used for example for vendor add-ons without disturbing Perl's +own library directories. + +=item * + +In many platforms the vendor-supplied 'cc' is too stripped-down to +build Perl (basically, 'cc' doesn't do ANSI C). If this seems +to be the case and 'cc' does not seem to be the GNU C compiler +'gcc', an automatic attempt is made to find and use 'gcc' instead. + +=item * + +gcc needs to closely track the operating system release to avoid +build problems. If Configure finds that gcc was built for a different +operating system release than is running, it now gives a clearly visible +warning that there may be trouble ahead. + +=item * + +If binary compatibility with the 5.005 release is not wanted, Configure +no longer suggests including the 5.005 modules in @INC. + +=item * + +Configure C<-S> can now run non-interactively. + +=item * + +Configure support for pdp11-style memory models has been removed due +to obsolescence. + +=item * + +configure.gnu now works with options with whitespace in them. + +=item * + +installperl now outputs everything to STDERR. + +=item * + +$Config{byteorder} is now computed dynamically (this is more robust +with "fat binaries" where an executable image contains binaries for +more than one binary platform.) + +=item * + +Because PerlIO is now the default on most platforms, "-perlio" doesn't +get appended to the $Config{archname} (also known as $^O) anymore. +Instead, if you explicitly choose not to use perlio (Configure command +line option -Uuseperlio), you will get "-stdio" appended. + +=item * + +Another change related to the architecture name is that "-64all" +(-Duse64bitall, or "maximally 64-bit") is appended only if your +pointers are 64 bits wide. (To be exact, the use64bitall is ignored.) + +=item * + +In AFS installations one can configure the root of the AFS to be +somewhere else than the default F by using the Configure +parameter C<-Dafsroot=/some/where/else>. + +=item * + +APPLLIB_EXP, a less-know configuration-time definition, has been +documented. It can be used to prepend site-specific directories +to Perl's default search path (@INC), see INSTALL for information. + +=item * + +The version of Berkeley DB used when the Perl (and, presumably, the +DB_File extension) was built is now available as +C<@Config{qw(db_version_major db_version_minor db_version_patch)}> +from Perl and as C from C. + +=item * + +Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM +has been documented in INSTALL. + +=item * + +If you have CPAN access (either network or a local copy such as a +CD-ROM) you can during specify extra modules to Configure to build and +install with Perl using the -Dextras=... option. See INSTALL for +more details. + +=item * + +In addition to config.over a new override file, config.arch, is +available. That is supposed to be used by hints file writers for +architecture-wide changes (as opposed to config.over which is for +site-wide changes). + +=item * + +If your file system supports symbolic links you can build Perl outside +of the source directory by + + mkdir /tmp/perl/build/directory + cd /tmp/perl/build/directory + sh /path/to/perl/source/Configure -Dmksymlinks ... + +This will create in /tmp/perl/build/directory a tree of symbolic links +pointing to files in /path/to/perl/source. The original files are left +unaffected. After Configure has finished you can just say + + make all test + +and Perl will be built and tested, all in /tmp/perl/build/directory. + +=item * + +For Perl developers several new make targets for profiling +and debugging have been added, see L. + +=over 8 + +=item * + +Use of the F tool to profile Perl has been documented in +L. There is a make target called "perl.gprof" for +generating a gprofiled Perl executable. + +=item * + +If you have GCC 3, there is a make target called "perl.gcov" for +creating a gcoved Perl executable for coverage analysis. See +L. + +=item * + +If you are on IRIX or Tru64 platforms, new profiling/debugging options +have been added, see L for more information about pixie and +Third Degree. + +=back + +=item * + +Guidelines of how to construct minimal Perl installations have +been added to INSTALL. + +=item * + +The Thread extension is now not built at all under ithreads +(C) because it wouldn't work anyway (the +Thread extension requires being Configured with C<-Duse5005threads>). + +But note that the Thread.pm interface is now shared by both +thread models. + +=back + +=head2 New Or Improved Platforms + +For the list of platforms known to support Perl, +see L. + +=over 4 + +=item * + +AIX dynamic loading should be now better supported. + +=item * + +AIX should now work better with gcc, threads, and 64-bitness. Also the +long doubles support in AIX should be better now. See L. + +=item * + +After a long pause, AmigaOS has been verified to be happy with Perl. + +=item * + +AtheOS (http://www.atheos.cx/) is a new platform. + +=item * + +DG/UX platform now supports the 5.005-style threads. See L. + +=item * + +DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2. + +=item * + +EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA) +have been regained. Many test suite tests still fail and the +co-existence of Unicode and EBCDIC isn't quite settled, but the +situation is much better than with Perl 5.6. See L, +L (for POSIX-BC), and L for more information. + +=item * + +Building perl with -Duseithreads or -Duse5005threads now works under +HP-UX 10.20 (previously it only worked under 10.30 or later). You will +need a thread library package installed. See README.hpux. + +=item * + +MacOS Classic (MacPerl has of course been available since +perl 5.004 but now the source code bases of standard Perl +and MacPerl have been synchronised) + +=item * + +MacOS X (or Darwin) should now be able to build Perl even on HFS+ +filesystems. (The case-insensitivity confused the Perl build process.) + +=item * + +NCR MP-RAS is now supported. + +=item * + +NetWare from Novell is now supported. See L. + +=item * + +NonStop-UX is now supported. + +=item * + +NEC SUPER-UX is now supported. + +=item * + +Amdahl UTS UNIX mainframe platform is now supported. + +=item * + +WinCE is now supported. See L. + +=item * + +z/OS (formerly known as OS/390, formerly known as MVS OE) has now +support for dynamic loading. This is not selected by default, +however, you must specify -Dusedl in the arguments of Configure. + +=back + +=head1 Selected Bug Fixes + +Numerous memory leaks and uninitialized memory accesses have been +hunted down. Most importantly anonymous subs used to leak quite +a bit. + +=over 4 + +=item * + +The autouse pragma didn't work for Multi::Part::Function::Names. + +=item * + +caller() could cause core dumps in certain situations. Carp was sometimes +affected by this problem. + +=item * + +chop(@list) in list context returned the characters chopped in +reverse order. This has been reversed to be in the right order. + +=item * + +Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm) +when building the Perl binary. The only exception to this is SunOS 4.x, +which needs them. + +=item * + +The behaviour of non-decimal but numeric string constants such as +"0x23" was platform-dependent: in some platforms that was seen as 35, +in some as 0, in some as a floating point number (don't ask). This +was caused by Perl using the operating system libraries in a situation +where the result of the string to number conversion is undefined: now +Perl consistently handles such strings as zero in numeric contexts. + +=item * + +The order of DESTROYs has been made more predictable. + +=item * + +Several debugger fixes: exit code now reflects the script exit code, +condition C<"0"> now treated correctly, the C command now checks +line number, the C<$.> no longer gets corrupted, all debugger output +now goes correctly to the socket if RemotePort is set. + +=item * + +Perl 5.6.0 could emit spurious warnings about redefinition of dl_error() +when statically building extensions into perl. This has been corrected. + +=item * + +L -R didn't work. + +=item * + +C<*foo{FORMAT}> now works. +=item * + +Infinity is now recognized as a number. + +=item * + +UNIVERSAL::isa no longer caches methods incorrectly. (This broke +the Tk extension with 5.6.0.) + +=item * + +Lexicals I: lexicals outside an eval "" weren't resolved +correctly inside a subroutine definition inside the eval "" if they +were not already referenced in the top level of the eval""ed code. + +=item * + +Lexicals II: lexicals leaked at file scope into subroutines that +were declared before the lexicals. + +=item * + +Lexical warnings now propagating correctly between scopes +and into C. + +=item * + +C did not work as intended. This has been +corrected. + +=item * + +warnings::enabled() now reports the state of $^W correctly if the caller +isn't using lexical warnings. + +=item * + +Line renumbering with eval and C<#line> now works. + +=item * + +Fixed numerous memory leaks, especially in eval "". + +=item * + +mkdir() now ignores trailing slashes in the directory name, +as mandated by POSIX. + +=item * + +Some versions of glibc have a broken modfl(). This affects builds +with C<-Duselongdouble>. This version of Perl detects this brokenness +and has a workaround for it. The glibc release 2.2.2 is known to have +fixed the modfl() bug. + +=item * + +Modulus of unsigned numbers now works (4063328477 % 65535 used to +return 27406, instead of 27047). + +=item * + +Some "not a number" warnings introduced in 5.6.0 eliminated to be +more compatible with 5.005. Infinity is now recognised as a number. + +=item * + +Numeric conversions did not recognize changes in the string value +properly in certain circumstances. + +=item * + +Attributes (like :shared) didn't work with our(). + +=item * + +our() variables will not cause "will not stay shared" warnings. + +=item * + +"our" variables of the same name declared in two sibling blocks +resulted in bogus warnings about "redeclaration" of the variables. +The problem has been corrected. + +=item * + +pack "Z" now correctly terminates the string with "\0". + +=item * + +Fix password routines which in some shadow password platforms +(e.g. HP-UX) caused getpwent() to return every other entry. + +=item * + +The PERL5OPT environment variable (for passing command line arguments +to Perl) didn't work for more than a single group of options. + +=item * + +PERL5OPT with embedded spaces didn't work. + +=item * + +printf() no longer resets the numeric locale to "C". + +=item * + +C now parses correctly as C<'a\\b'>. + +=item * + +pos() did not return the correct value within s///ge in earlier +versions. This is now handled correctly. + +=item * + +Printing quads (64-bit integers) with printf/sprintf now works +without the q L ll prefixes (assuming you are on a quad-capable platform). + +=item * + +Regular expressions on references and overloaded scalars now work. + +=item * + +Right-hand side magic (GMAGIC) could in many cases such as string +concatenation be invoked too many times. + +=item * + +scalar() now forces scalar context even when used in void context. + +=item * + +SOCKS support is now much more robust. + +=item * + +sort() arguments are now compiled in the right wantarray context +(they were accidentally using the context of the sort() itself). +The comparison block is now run in scalar context, and the arguments +to be sorted are always provided list context. + +=item * + +Changed the POSIX character class C<[[:space:]]> to include the (very +rarely used) vertical tab character. Added a new POSIX-ish character +class C<[[:blank:]]> which stands for horizontal whitespace +(currently, the space and the tab). + +=item * + +The tainting behaviour of sprintf() has been rationalized. It does +not taint the result of floating point formats anymore, making the +behaviour consistent with that of string interpolation. + +=item * + +Some cases of inconsistent taint propagation (such as within hash +values) have been fixed. + +=item * + +The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds +of simple pattern matches. These are now handled better. + +=item * + +Regular expression debug output (whether through C +or via C<-Dr>) now looks better. + +=item * + +Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The +bug has been fixed. + +=item * + +Use of $& could trigger a core dump under some situations. This +is now avoided. + +=item * + +The regular expression captured submatches ($1, $2, ...) are now +more consistently unset if the match fails, instead of leaving false +data lying around in them. + +=item * + +readline() on files opened in "slurp" mode could return an extra "" at +the end in certain situations. This has been corrected. + +=item * + +Autovivification of symbolic references of special variables described +in L (as in C<${$num}>) was accidentally disabled. This works +again now. + +=item * + +Sys::Syslog ignored the C constant. + +=item * + +All but the first argument of the IO syswrite() method are now optional. + +=item * + +$AUTOLOAD, sort(), lock(), and spawning subprocesses +in multiple threads simultaneously are now thread-safe. + +=item * + +Tie::ARRAY SPLICE method was broken. + +=item * + +Allow read-only string on left hand side of non-modifying tr///. + +=item * + +Several Unicode fixes. + +=over 8 + +=item * + +BOMs (byte order marks) in the beginning of Perl files +(scripts, modules) should now be transparently skipped. +UTF-16 (UCS-2) encoded Perl files should now be read correctly. + +=item * + +The character tables have been updated to Unicode 3.1.1. + +=item * + +Comparing with utf8 data does not magically upgrade non-utf8 data +into utf8. + +=item * + +C, C, and C now match titlecase. + +=item * + +Concatenation with the C<.> operator or via variable interpolation, +C, C, C, C, the C operator, +substitution with C, single-quoted UTF8, should now work. + +=item * + +The C operator now works. Note that the C +functionality has been removed (but see pack('U0', ...)). + +=item * -=head1 Utility Changes +C now works. -=head1 Improved Documentation +=item * -=head1 Performance enhancements +Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings. +This has been corrected. -=head1 Installation and Configuration Improvements +=item * + +Zero entries were missing from the Unicode classes like C. + +=back + +=item * + +Large unsigned numbers (those above 2**31) could sometimes lose their +unsignedness, causing bogus results in arithmetic operations. + +=back + +=head2 Platform Specific Changes and Fixes + +=over 4 + +=item * + +BSDI 4.* + +Perl now works on post-4.0 BSD/OSes. + +=item * + +All BSDs + +Setting C<$0> now works (as much as possible; see L for details). + +=item * + +Cygwin + +Numerous updates; currently synchronised with Cygwin 1.1.4. + +=item * + +Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O. + +=item * + +EPOC + +EPOC update after Perl 5.6.0. See README.epoc. + +=item * + +FreeBSD 3.* + +Perl now works on post-3.0 FreeBSDs. + +=item * + +HP-UX + +README.hpux updated; C now almost works. + +=item * + +IRIX + +Numerous compilation flag and hint enhancements; accidental mixing +of 32-bit and 64-bit libraries (a doomed attempt) made much harder. + +=item * + +Linux + +=over 8 + +=item * + +Long doubles should now work (see INSTALL). + +=item * + +Linux previously had problems related to sockaddrlen when using +accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname(). + +=back + +=item * + +MacOS Classic + +Compilation of the standard Perl distribution in MacOS Classic should +now work if you have the Metrowerks development environment and +the missing Mac-specific toolkit bits. Contact the macperl mailing +list for details. + +=item * + +MPE/iX + +MPE/iX update after Perl 5.6.0. See README.mpeix. + +=item * + +NetBSD/sparc + +Perl now works on NetBSD/sparc. + +=item * + +OS/2 + +Now works with usethreads (see INSTALL). + +=item * + +Solaris + +64-bitness using the Sun Workshop compiler now works. + +=item * + +Tru64 (aka Digital UNIX, aka DEC OSF/1) + +The operating system version letter now recorded in $Config{osvers}. +Allow compiling with gcc (previously explicitly forbidden). Compiling +with gcc still not recommended because buggy code results, even with +gcc 2.95.2. + +=item * -=head1 Platform specific changes +Unicos -=head1 Significant bug fixes +Fixed various alignment problems that lead into core dumps either +during build or later; no longer dies on math errors at runtime; +now using full quad integers (64 bits), previously was using +only 46 bit integers for speed. + +=item * + +VMS + +chdir() now works better despite a CRT bug; now works with MULTIPLICITY +(see INSTALL); now works with Perl's malloc. + +The tainting of C<%ENV> elements via C or C was previously +unimplemented. It now works as documented. + +The C emulation has been improved. The worst bug (now fixed) +was that a pid of -1 would cause a wildcard search of all processes on +the system. The most significant enhancement is that we can now +usually get the completion status of a terminated process. + +POSIX-style signals are now emulated much better on VMS versions prior +to 7.0. + +The C function and backticks operator have improved +functionality and better error handling. + +=item * + +Windows + +=over 8 + +=item * + +accept() no longer leaks memory. + +=item * + +Borland C++ v5.5 is now a supported compiler that can build Perl. +However, the generated binaries continue to be incompatible with those +generated by the other supported compilers (GCC and Visual C++). + +=item * + +Better chdir() return value for a non-existent directory. + +=item * + +Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x. + +=item * + +New %ENV entries now propagate to subprocesses. + +=item * + +Current directory entries in %ENV are now correctly propagated to child +processes. + +=item * + +$ENV{LIB} now used to search for libs under Visual C. + +=item * + +fork() emulation has been improved in various ways, but still continues +to be experimental. See L for known bugs and caveats. + +=item * + +A failed (pseudo)fork now returns undef and sets errno to EAGAIN. + +=item * + +Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root. +Other bugs in chdir() and Cwd::cwd() have also been fixed. + +=item * + +HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html + +=item * + +The makefiles now provide a single switch to bulk-enable all the features +enabled in ActiveState ActivePerl (a popular Win32 binary distribution). + +=item * + +Allow REG_EXPAND_SZ keys in the registry. + +=item * + +Can now send() from all threads, not just the first one. + +=item * + +Fake signal handling reenabled, bugs and all. + +=item * + +%SIG has been enabled under USE_ITHREADS, but its use is completely +unsupported under all configurations. + +=item * + +Less stack reserved per thread so that more threads can run +concurrently. (Still 16M per thread.) + +=item * + +C now prefers C:/temp over /tmp +(works better when perl is running as service). + +=item * + +Better UNC path handling under ithreads. + +=item * + +wait(), waitpid() and backticks now return the correct exit status under +Windows 9x. + +=item * + +winsock handle leak fixed. + +=back + +=back =head1 New or Changed Diagnostics =over 4 -=item (perhaps you forgot to load "%s"?) +=item * + +All regular expression compilation error messages are now hopefully +easier to understand both because the error message now comes before +the failed regex and because the point of failure is now clearly +marked by a C-- HERE> marker. + +=item * + +The various "opened only for", "on closed", "never opened" warnings +drop the C prefix for filehandles in the C
package, +for example C instead of C. + +=item * + +The "Unrecognized escape" warning has been extended to include C<\8>, +C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters. + +=item * + +Two new debugging options have been added: if you have compiled your +Perl with debugging, you can use the -DT and -DR options to trace +tokenising and to add reference counts to displaying variables, +respectively. + +=item * + +If an attempt to use a (non-blessed) reference as an array index +is made, a warning is given. + +=item * + +C and C (with no values to push or unshift) +now give a warning. This may be a problem for generated and evaled +code. + +=item * + +If you try to L a number less than 0 or larger than 255 +using the C<"C"> format you will get an optional warning. Similarly +for the C<"c"> format and a number less than -128 or more than 127. + +=item * + +Certain regex modifiers such as C<(?o)> make sense only if applied to +the entire regex. You will an optional warning if you try to do otherwise. + +=item * + +Using arrays or hashes as references (e.g. C<< %foo->{bar} >> +has been deprecated for a while. Now you will get an optional warning. + +=back + +=head1 Changed Internals + +=over 4 + +=item * + +perlapi.pod (a companion to perlguts) now attempts to document the +internal API. + +=item * + +You can now build a really minimal perl called microperl. +Building microperl does not require even running Configure; +C should be enough. Beware: microperl makes +many assumptions, some of which may be too bold; the resulting +executable may crash or otherwise misbehave in wondrous ways. +For careful hackers only. + +=item * + +Added rsignal(), whichsig(), do_join(), op_clear, op_null, +ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8 +interfaces to the publicised API. For the full list of the available +APIs see L. + +=item * + +Made possible to propagate customised exceptions via croak()ing. + +=item * + +Now xsubs can have attributes just like subs. (Well, at least the +built-in attributes.) + +=item * + +dTHR and djSP have been obsoleted; the former removed (because it's +a no-op) and the latter replaced with dSP. + +=item * + +PERL_OBJECT has been completely removed. + +=item * + +The MAGIC constants (e.g. C<'P'>) have been macrofied +(e.g. C) for better source code readability +and maintainability. + +=item * + +The regex compiler now maintains a structure that identifies nodes in +the compiled bytecode with the corresponding syntactic features of the +original regex expression. The information is attached to the new +C member of the C. See L for more +complete information. -(F) This is an educated guess made in conjunction with the message -"Can't locate object method \"%s\" via package \"%s\"". It often means -that a method requires a package that has not been loaded. +=item * + +The C code has been made much more C clean. Some warning +messages still remain in some platforms, so if you are compiling with +gcc you may see some warnings about dubious practices. The warnings +are being worked on. + +=item * + +F, F, and F have now been extensively commented. + +=item * + +Documentation on how to use the Perl source repository has been added +to F. + +=item * + +There are now several profiling make targets. =back -=head1 New tests +=head1 Security Vulnerability Closed -=head1 Incompatible Changes +(This change was already made in 5.7.0 but bears repeating here.) + +A potential security vulnerability in the optional suidperl component +of Perl was identified in August 2000. suidperl is neither built nor +installed by default. As of November 2001 the only known vulnerable +platform is Linux, most likely all Linux distributions. CERT and +various vendors and distributors have been alerted about the vulnerability. +See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt +for more information. + +The problem was caused by Perl trying to report a suspected security +exploit attempt using an external program, /bin/mail. On Linux +platforms the /bin/mail program had an undocumented feature which +when combined with suidperl gave access to a root shell, resulting in +a serious compromise instead of reporting the exploit attempt. If you +don't have /bin/mail, or if you have 'safe setuid scripts', or if +suidperl is not installed, you are safe. + +The exploit attempt reporting feature has been completely removed from +Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also +from all the Perl 5.7 releases), so that particular vulnerability +isn't there anymore. However, further security vulnerabilities are, +unfortunately, always possible. The suidperl functionality is most +probably going to be removed in Perl 5.10. In any case, suidperl +should only be used by security experts who know exactly what they are +doing and why they are using suidperl instead of some other solution +such as sudo (see http://www.courtesan.com/sudo/). + +=head1 New Tests + +Several new tests have been added, especially for the F +subsection. There are now about 34 000 individual tests (spread over +about 530 test scripts), in the regression suite (5.6.1 has about +11700 tests, in 258 test scripts) Many of the new tests are introduced +by the new modules, but still in general Perl is now more thoroughly +tested. + +Because of the large number of tests, running the regression suite +will take considerably longer time than it used to: expect the suite +to take up to 4-5 times longer to run than in perl 5.6. In a really +fast machine you can hope to finish the suite in about 5 minutes +(wallclock time). + +The tests are now reported in a different order than in earlier Perls. +(This happens because the test scripts from under t/lib have been moved +to be closer to the library/extension they are testing.) =head1 Known Problems -=head1 Obsolete Diagnostics +=head2 AIX + +=over 4 + +=item * + +In AIX 4.2 Perl extensions that use C++ functions that use statics +may have problems in that the statics are not getting initialized. +In newer AIX releases this has been solved by linking Perl with +the libC_r library, but unfortunately in AIX 4.2 the said library +has an obscure bug where the various functions related to time +(such as time() and gettimeofday()) return broken values, and +therefore in AIX 4.2 Perl is not linked against the libC_r. + +=item * + +vac 5.0.0.0 May Produce Buggy Code For Perl + +The AIX C compiler vac version 5.0.0.0 may produce buggy code, +resulting in few random tests failing, but when the failing tests +are run by hand, they succeed. We suggest upgrading to at least +vac version 5.0.1.0, that has been known to compile Perl correctly. +"lslpp -L|grep vac.C" will tell you the vac version. + +=back + +=head2 Amiga Perl Invoking Mystery + +One cannot call Perl using the C syntax, that is, C +works, but for example C doesn't. The exact reason isn't +known but the current suspect is the F library. + +=head2 lib/ftmp-security tests warn 'system possibly insecure' + +Don't panic. Read INSTALL 'make test' section instead. + +=head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12 + +The subtests 11 and 12 sometimes fail and sometimes work. + +=head2 HP-UX lib/io_multihomed Fails When LP64-Configured + +The lib/io_multihomed test may hang in HP-UX if Perl has been +configured to be 64-bit. Because other 64-bit platforms do not hang in +this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The +test attempts to create and connect to "multihomed" sockets (sockets +which have multiple IP addresses). + +=head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured + +If perl is configured with -Duse64bitall, the successful result of the +subtest 10 of lib/posix may arrive before the successful result of the +subtest 9, which confuses the test harness so much that it thinks the +subtest 9 failed. + +=head2 Linux With Sfio Fails op/misc Test 48 + +No known fix. + +=head2 Mac OS X + +The following tests are known to fail: + + Failed Test Stat Wstat Total Fail Failed List of Failed + ------------------------------------------------------------------------- + ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ?? + ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65 + ../ext/POSIX/t/posix.t 31 1 3.23% 10 + ../lib/warnings.t 450 1 0.22% 316 + +=head2 OS/390 + +OS/390 has rather many test failures but the situation is actually +better than it was in 5.6.0, it's just that so many new modules and +tests have been added. + + Failed Test Stat Wstat Total Fail Failed List of Failed + ----------------------------------------------------------------------------- + ../ext/B/Deparse.t 14 1 7.14% 14 + ../ext/B/Showlex.t 1 1 100.00% 1 + ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598 + 600 602 604-610 + ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5 + ../ext/POSIX/POSIX.t 29 1 3.45% 14 + ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5 + ../lib/locale.t 129 33024 117 19 16.24% 99-117 + ../lib/warnings.t 434 1 0.23% 75 + ../lib/ExtUtils.t 27 1 3.70% 25 + ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145 + ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81 + ../lib/User/pwent.t 9 1 11.11% 4 + op/pat.t 660 6 0.91% 242-243 424-425 + 626-627 + op/split.t 0 9 ?? ?? % ?? + op/taint.t 174 3 1.72% 156 162 168 + op/tr.t 70 3 4.29% 50 58-59 + Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay. + +=head2 op/sprintf tests 129 and 130 + +The op/sprintf tests 129 and 130 are known to fail on some platforms. +Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX. +The failing platforms do not comply with the ANSI C Standard, line +19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce +something other than "1" and "-1" when formatting 0.6 and -0.6 using +the printf format "%.0f", most often they produce "0" and "-0".) + +=head2 Failure of Thread tests + +B + +The following tests are known to fail due to fundamental problems in +the 5.005 threading implementation. These are not new failures--Perl +5.005_0x has the same bugs, but didn't have these tests. + + ext/List/Util/t/first 2 + lib/autouse 4 + ext/Thread/thr5005 19-20 + +These failures are unlikely to get fixed. + +=head2 UNICOS + +=over 4 + +=item * + +ext/POSIX/sigaction subtests 6 and 13 may fail. + +=item * + +lib/ExtUtils may spuriously claim that subtest 28 failed, +which is interesting since the test only has 27 tests. + +=item * + +Numerous numerical test failures + + op/numconvert 209,210,217,218 + op/override 7 + ext/Time/HiRes/HiRes 9 + lib/Math/BigInt/t/bigintpm 1145 + lib/Math/Trig 25 + +These tests fail because of yet unresolved floating point inaccuracies. + +=back + +=head2 UTS + +There are a few known test failures, see L. + +=head2 VMS + +There is one known test failure with a default configuration: + + [.run]switches..........................FAILED on test 1 + +=head2 Win32 + +In multi-CPU boxes there are some problems with the I/O buffering: +some output may appear twice. + +=head2 Localising a Tied Variable Leaks Memory + + use Tie::Hash; + tie my %tie_hash => 'Tie::StdHash'; + + ... + + local($tie_hash{Foo}) = 1; # leaks + +Code like the above is known to leak memory every time the local() +is executed. + +=head2 Localising Tied Arrays and Hashes Is Broken + + local %tied_array; + +doesn't work as one would expect: the old value is restored +incorrectly. + +=head2 Self-tying of Arrays and Hashes Is Forbidden + +Self-tying of arrays and hashes is broken in rather deep and +hard-to-fix ways. As a stop-gap measure to avoid people from getting +frustrated at the mysterious results (core dumps, most often) it is +for now forbidden (you will get a fatal error even from an attempt). + +=head2 Building Extensions Can Fail Because Of Largefiles + +Some extensions like mod_perl are known to have issues with +`largefiles', a change brought by Perl 5.6.0 in which file offsets +default to 64 bits wide, where supported. Modules may fail to compile +at all or compile and work incorrectly. Currently there is no good +solution for the problem, but Configure now provides appropriate +non-largefile ccflags, ldflags, libswanted, and libs in the %Config +hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are +having problems can try configuring themselves without the +largefileness. This is admittedly not a clean solution, and the +solution may not even work at all. One potential failure is whether +one can (or, if one can, whether it's a good idea) link together at +all binaries with different ideas about file offsets, all this is +platform-dependent. + +=head2 Unicode Support on EBCDIC Still Spotty + +Though mostly working, Unicode support still has problem spots on +EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}> +regular expression constructs for code points less than 256: the +pP are testing for Unicode code points, not knowing about EBCDIC. + +=head2 The Compiler Suite Is Still Experimental + +The compiler suite is slowly getting better but it continues to be +highly experimental. Use in production environments is discouraged. + +=head2 The Long Double Support Is Still Experimental + +The ability to configure Perl's numbers to use "long doubles", +floating point numbers of hopefully better accuracy, is still +experimental. The implementations of long doubles are not yet +widespread and the existing implementations are not quite mature +or standardised, therefore trying to support them is a rare +and moving target. The gain of more precision may also be offset +by slowdown in computations (more bits to move around, and the +operations are more likely to be executed by less optimised +libraries). + +=head2 Seen In Perl 5.7 But Gone Now + +Some modules were seen in the Perl 5.7 development releases +but are not present in 5.8.0. + +=over 4 + +=item * + +C was removed because the implementation of C +variable attributes changed so much that the Attribute::Handlers will +require a major rewrite. (This means that you can't use +Attribute::Handler 0.76 with Perl 5.8.0.) + +=item * + +C (previously known as C) was removed +because it was felt that it didn't have enough value in it to be a +core module. It is still a useful module, though, and is available +from the CPAN. + +=back =head1 Reporting Bugs -If you find what you think is a bug, you might check the -articles recently posted to the comp.lang.perl.misc newsgroup. -There may also be information at http://www.perl.com/perl/, the Perl -Home Page. +If you find what you think is a bug, you might check the articles +recently posted to the comp.lang.perl.misc newsgroup and the perl +bug database at http://bugs.perl.org. There may also be +information at http://www.perl.com/perl/, the Perl Home Page. If you believe you have an unreported bug, please run the B program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the -output of C, will be sent off to perlbug@perl.com to be +output of C, will be sent off to perlbug@perl.org to be analysed by the Perl porting team. =head1 SEE ALSO @@ -67,9 +2615,6 @@ The F and F files for copyright information. =head1 HISTORY -Written by Gurusamy Sarathy >, with many -contributions from The Perl Porters. - -Send omissions or corrections to >. +Written by Jarkko Hietaniemi >. =cut