Many of the bug fixes in 5.8.0 were already seen in the 5.6.1maintenance release since the two releases were kept closelycoordinated (while 5.8.0 was still called 5.7.something).

Changes that were integrated into the 5.6.1 release are marked [561].Many of these changes have been further developed since 5.6.1 was released,those are marked [561+].

You can see the list of changes in the 5.6.1 release (both from the5.005_03 release and the 5.6.0 release) by reading perl561delta.

Highlights In 5.8.0

Better Unicode support
New IO Implementation
New Thread Implementation
Better Numeric Accuracy
Safe Signals
Many New Modules
More Extensive Regression Testing

Incompatible Changes

Binary Incompatibility

Perl 5.8 is not binary compatible with earlier releases of Perl.

You have to recompile your XS modules.

(Pure Perl modules should continue to work.)

The major reason for the discontinuity is the new IO architecturecalled PerlIO. PerlIO is the default configuration because withoutit many new features of Perl 5.8 cannot be used. In other words:you just have to recompile your modules containing XS code, sorryabout that.

In future releases of Perl, non-PerlIO aware XS modules may becomecompletely unsupported. This shouldn't be too difficult for moduleauthors, however: PerlIO has been designed as a drop-in replacement(at the source code level) for the stdio interface.

Depending on your platform, there are also other reasons whywe decided to break binary compatibility, please read on.

64-bit platforms and malloc

If your pointers are 64 bits wide, the Perl malloc is no longer beingused because it does not work well with 8-byte pointers. Also,usually the system mallocs on such platforms are much better optimizedfor such large memory models than the Perl malloc. Some memory-hungryPerl applications like the PDL don't work well with Perl's malloc.Finally, other applications than Perl (such as mod_perl) tend to preferthe system malloc. Such platforms include Alpha and 64-bit HPPA,MIPS, PPC, and Sparc.

AIX Dynaloading

The AIX dynaloading now uses in AIX releases 4.3 and newer the nativedlopen interface of AIX instead of the old emulated interface. Thischange will probably break backward compatibility with compiledmodules. The change was made to make Perl more compliant with otherapplications like mod_perl which are using the AIX native interface.

Attributes for `my` variables now handled at run-time

The my EXPR : ATTRS syntax now applies variable attributes atrun-time. (Subroutine and our variables still get attributes appliedat compile-time.) See attributes for additional details. In particular,however, this allows variable attributes to be useful for tie interfaces,which was a deficiency of earlier releases. Note that the new semanticsdoesn't work with the Attribute::Handlers module (as of version 0.76).

Socket Extension Dynamic in VMS

The Socket extension is now dynamically loaded instead of beingstatically built in. This may or may not be a problem with ancientTCP/IP stacks of VMS: we do not know since we weren't able to testPerl in such configurations.

IEEE-format Floating Point Default on OpenVMS Alpha

Perl now uses IEEE format (T_FLOAT) as the default internal floatingpoint format on OpenVMS Alpha, potentially breaking binary compatibilitywith external libraries or existing data. G_FLOAT is still available asa configuration option. The default on VAX (D_FLOAT) has not changed.

New Unicode Semantics (no more `use utf8`, almost)

Previously in Perl 5.6 to use Unicode one would say "use utf8" andthen the operations (like string concatenation) were Unicode-awarein that lexical scope.

This was found to be an inconvenient interface, and in Perl 5.8 theUnicode model has completely changed: now the "Unicodeness" is boundto the data itself, and for most of the time "use utf8" is not neededat all. The only remaining use of "use utf8" is when the Perl scriptitself has been written in the UTF-8 encoding of Unicode. (UTF-8 hasnot been made the default since there are many Perl scripts out therethat are using various national eight-bit character sets, which wouldbe illegal in UTF-8.)

See perluniintro for the explanation of the current model,and utf8 for the current use of the utf8 pragma.

New Unicode Properties

Unicode scripts are now supported. Scripts are similar to (and superiorto) Unicode blocks. The difference between scripts and blocks is thatscripts are the glyphs used by a language or a group of languages, whilethe blocks are more artificial groupings of (mostly) 256 characters basedon the Unicode numbering.

In general, scripts are more inclusive, but not universally so. Forexample, while the script Latin includes all the Latin characters andtheir various diacritic-adorned versions, it does not include the variouspunctuation or digits (since they are not solely Latin).

A number of other properties are now supported, including \p{L&},\p{Any} \p{Assigned}, \p{Unassigned}, \p{Blank} [561] and\p{SpacePerl} [561] (along with their \P{...} versions, of course).See perlunicode for details, and more additions.

The In or Is prefix to names used with the \p{...} and \P{...}are now almost always optional. The only exception is that a In prefixis required to signify a Unicode block when a block name conflicts with ascript name. For example, \p{Tibetan} refers to the script, while\p{InTibetan} refers to the block. When there is no name conflict, youcan omit the In from the block name (e.g. \p{BraillePatterns}), butto be safe, it's probably best to always use the In).

REF(...) Instead Of SCALAR(...)

A reference to a reference now stringifies as "REF(0x81485ec)" insteadof "SCALAR(0x81485ec)" in order to be more consistent with the returnvalue of ref().

pack/unpack D/F recycled

The undocumented pack/unpack template letters D/F have been recycledfor better use: now they stand for long double (if supported by theplatform) and NV (Perl internal floating point type). (They usedto be aliases for d/f, but you never knew that.)

glob() now returns filenames in alphabetical order

The list of filenames from glob() (or <...>) is now by default sortedalphabetically to be csh-compliant (which is what happened beforein most Unix platforms). (bsd_glob() does still sort platformnatively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) [561]

Deprecations

The semantics of bless(REF, REF) were unclear and until someone provesit to make some sense, it is forbidden.
The obsolete chat2 library that should never have been allowedto escape the laboratory has been decommissioned.
Using chdir("") or chdir(undef) instead of explicit chdir() isdoubtful. A failure (think chdir(some_function()) can lead intounintended chdir() to the home directory, therefore this behaviouris deprecated.
The builtin dump() function has probably outlived most of itsusefulness. The core-dumping functionality will remain in futureavailable as an explicit call to CORE::dump(), but in futurereleases the behaviour of an unqualified dump() call may change.
The very dusty examples in the eg/ directory have been removed.Suggestions for new shiny examples welcome but the main issue is thatthe examples need to be documented, tested and (most importantly)maintained.
The (bogus) escape sequences \8 and \9 now give an optional warning("Unrecognized escape passed through"). There is no need to \-escapeany \w character.
The *glob{FILEHANDLE} is deprecated, use *glob{IO} instead.
The package; syntax (package without an argument) has beendeprecated. Its semantics were never that clear and itsimplementation even less so. If you have used that feature todisallow all but fully qualified variables, use strict; instead.
The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are stillrecognised but now cause fatal errors. The previous behaviour ofignoring them by default and warning if requested was unacceptablesince it, in a way, falsely promised that the features could be used.
In future releases, non-PerlIO aware XS modules may become completelyunsupported. Since PerlIO is a drop-in replacement for stdio at thesource code level, this shouldn't be that drastic a change.
Previous versions of perl and some readings of some sections of CamelIII implied that the :raw "discipline" was the inverse of :crlf.Turning off "clrfness" is no longer enough to make a stream trulybinary. So the PerlIO :raw layer (or "discipline", to use the Camelbook's older terminology) is now formally defined as being equivalentto binmode(FH) - which is in turn defined as doing whatever isnecessary to pass each byte as-is without any translation. Inparticular binmode(FH) - and hence :raw - will now turn off bothCRLF and UTF-8 translation and remove other layers (e.g. :encoding())which would modify byte stream.
The current user-visible implementation of pseudo-hashes (the weirduse of the first array element) is deprecated starting from Perl 5.8.0and will be removed in Perl 5.10.0, and the feature will beimplemented differently. Not only is the current interface ratherugly, but the current implementation slows down normal array and hashuse quite noticeably. The fields pragma interface will remainavailable. The restricted hashes interface is expected tobe the replacement interface (see Hash::Util). If your existingprograms depends on the underlying implementation, consider usingClass::PseudoHash from CPAN.
The syntaxes @a->[...] and %h->{...} have now been deprecated.
After years of trying, suidperl is considered to be too complex toever be considered truly secure. The suidperl functionality is likelyto be removed in a future release.
The 5.005 threads model (module Thread) is deprecated and expectedto be removed in Perl 5.10. Multithreaded code should be migrated tothe new ithreads model (see threads, threads::shared andperlthrtut).
The long deprecated uppercase aliases for the string comparisonoperators (EQ, NE, LT, LE, GE, GT) have now been removed.
The tr///C and tr///U features have been removed and will not return;the interface was a mistake. Sorry about that. For similarfunctionality, see pack('U0', ...) and pack('C0', ...). [561]
Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".The prototypes are now checked better at compile-time for invalidsyntax. An optional warning is generated ("Illegal character inprototype...") but this may be upgraded to a fatal error in a futurerelease.
The exec LIST and system LIST operations now produce warnings ontainted data and in some future release they will produce fatal errors.
The existing behaviour when localising tied arrays and hashes is wrong,and will be changed in a future release, so do not rely on the existingbehaviour. See Localising Tied Arrays and Hashes Is Broken.

Core Enhancements

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 inregular expressions should work now, Unicode in tr/// should work now,Unicode in I/O should work now. See perluniintro for introductionand perlunicode for details.

The Unicode Character Database coming with Perl has been upgradedto Unicode 3.2.0. For more information, see http://www.unicode.org/ .[561+] (5.6.1 has UCD 3.0.1.)
For developers interested in enhancing Perl's Unicode capabilities:almost all the UCD files are included with the Perl distribution inthe lib/unicore subdirectory. The most notable omission, for spaceconsiderations, is the Unihan database.
The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is likeC isblank(), that is, it contains only "horizontal whitespace" (the spacecharacter is, the newline isn't), and the "SpacePerl" is the Unicodeequivalent of \s (\p{Space} isn't, since that includes the verticaltabulator character, whereas \s doesn't.)
See "New Unicode Properties" earlier in this document for additionalinformation on changes with Unicode properties.

PerlIO is Now The Default

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 thehandle's behaviour. Layers can be specified at open time via 3-argform of open:
```
   open($fh,'>:crlf :utf8', $path) || ...
 
```
or on already opened handles via extended binmode:
```
   binmode($fh,':encoding(iso-8859-7)');
 
```
The built-in layers are: unix (low level read/write), stdio (as inprevious Perls), perlio (re-implementation of stdio buffering in aportable manner), crlf (does CRLF <=> "\n" translation as on Win32,but available on any platform). A mmap layer may be available ifplatform supports it (mostly Unixes).
Layers to be applied by default may be specified via the 'open' pragma.
See Installation and Configuration Improvements for the effectsof PerlIO on your architecture name.
If your platform supports fork(), you can use the list form of openfor pipes. For example:
```
 open KID_PS, "-|", "ps", "aux" or die $!;
 
```
forks the ps(1) command (without spawning a shell, as there are morethan three arguments to open()), and reads its standard output via theKID_PS filehandle. See perlipc.
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 namedfor you since it's not UTF-8 what you will be getting but insteadUTF-EBCDIC. See perlunicode, utf8, andhttp://www.unicode.org/unicode/reports/tr16/ for more information.In future releases this naming may change. See perluniintrofor more information about UTF-8.
If your environment variables (LC_ALL, LC_CTYPE, LANG) look like youwant to use UTF-8 (any of the variables match /utf-?8/i), yourSTDIN, STDOUT, STDERR handles and the default open layer (see open)are marked as UTF-8. (This feature, like other new features thatcombine Unicode and I/O, work only if you are using PerlIO, but that'sthe default.)
Note that after this Perl really does assume that everything is UTF-8:for example if some input handle is not, Perl will probably very sooncomplain about the input data like this "Malformed UTF-8 ..." sinceany old eight-bit data is not legal UTF-8.
Note for code authors: if you want to enable your users to use UTF-8as their default encoding but in your code still have eight-bit I/O streams(such as images or zip files), you need to explicitly open() or binmode()with :bytes (see open and binmode), or youcan just use binmode(FH) (nice for pre-5.8.0 backward compatibility).
File handles can translate character encodings from/to Perl's internalUnicode form on read/write via the ":encoding()" layer.
File handles can be opened to "in memory" files held in Perl scalars via:
```
   open($fh,'>', \$variable) || ...
 
```
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.

ithreads

The new interpreter threads ("ithreads" for short) implementation ofmultithreading, by Arthur Bergman, replaces the old "5.005 threads"implementation. In the ithreads model any data sharing betweenthreads must be explicit, as opposed to the model where data sharingwas implicit. See threads and threads::shared, andperlthrtut.

As a part of the ithreads implementation Perl will also useany necessary and detectable reentrant libc interfaces.

Restricted Hashes

A restricted hash is restricted to a certain set of keys, no keysoutside the set can be added. Also individual keys can be restrictedso that the key cannot be deleted and the value cannot be changed.No new syntax is involved: the Hash::Util module is the interface.

Safe Signals

Perl used to be fragile in that signals arriving at inopportune momentscould corrupt Perl's internal state. Now Perl postpones handling ofsignals until it's safe (between opcodes).

This change may have surprising side effects because signals no longerinterrupt Perl instantly. Perl will now first finish whatever it wasdoing, like finishing an internal operation (like sort()) or anexternal operation (like an I/O operation), and only then look at anyarrived signals (and before starting the next operation). No more corruptinternal state since the current operation is always finished first,but the signal may take more time to get heard. Note that breakingout from potentially blocking operations should still work, though.

Understanding of Numbers

In general a lot of fixing has happened in the area of Perl'sunderstanding of numbers, both integer and floating point. Since inmany systems the standard number parsing functions like strtoul()and atof() seem to have bugs, Perl tries to work around theirdeficiencies. This results hopefully in more accurate numbers.

Perl now tries internally to use integer values in numeric conversionsand basic arithmetics (+ - * /) if the arguments are integers, andtries also to keep the results stored internally as integers.This change leads to often slightly faster and always less lossyarithmetics. (Previously Perl always preferred floating point numbersin its math.)

Arrays now always interpolate into double-quoted strings [561]

In double-quoted strings, arrays now interpolate, no matter what. Thebehavior in earlier versions of perl 5 was that arrays would interpolateinto strings if the array had been mentioned before the string wascompiled, and otherwise Perl would raise a fatal compile-time error.In versions 5.000 through 5.003, the error was

 Literal @example now requires backslash

In versions 5.004_01 through 5.6.0, the error was

 In string, @example now must be written as \@example

The idea here was to get people into the habit of writing"fred\@example.com" when they wanted a literal @ sign, just asthey have always written "Give me back my \$5" when they wanted aliteral $ sign.

Starting with 5.6.1, when Perl now sees an @ sign in adouble-quoted string, it always attempts to interpolate an array,regardless of whether or not the array has been used or declaredalready. The fatal error has been downgraded to an optional warning:

 Possible unintended interpolation of @example in string

This warns you that "[email protected]" is going to turn intofred.com if you don't backslash the @.See http://perl.plover.com/at-error.html for more detailsabout the history here.

Miscellaneous Changes

AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attributeto AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
The $Config{byteorder} (and corresponding BYTEORDER in config.h) waspreviously wrong in platforms if sizeof(long) was 4, but sizeof(IV)was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321),but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321).(This problem didn't affect Windows platforms.)
Also, $Config{byteorder} is now computed dynamically--this is morerobust with "fat binaries" where an executable image contains binariesfor more than one binary platform, and when cross-compiling.
perl -d:Module=arg,arg,arg now works (previously one couldn't passin multiple arguments.)
do followed by a bareword now ensures that this bareword isn'ta keyword (to avoid a bug where do q(foo.pl) tried to call asubroutine called q). This means that for example instead ofdo format() you must write do &format().
The builtin dump() now gives an optional warningdump() better written as CORE::dump(),meaning that by default dump(...) is resolved as the builtindump() which dumps core and aborts, not as (possibly) user-definedsub dump. To call the latter, qualify the call as &dump(...).(The whole dump() feature is to considered deprecated, and possiblyremoved/changed in future releases.)
chomp() and chop() are now overridable. Note, however, that theirprototype (as given by prototype("CORE::chomp") is undefined,because it cannot be expressed and therefore one cannot really writereplacements to override these builtins.
END blocks are now run even if you exit/die in a BEGIN block.Internally, the execution of END blocks is now controlled byPL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the newbehaviour for Perl embedders. This will default in 5.10. Seeperlembed.
Formats now support zero-padded decimal fields.
Although "you shouldn't do that", it was possible to write code thatdepends on Perl's hashed key order (Data::Dumper does this). The newalgorithm "One-at-a-Time" produces a different hashed key order.More details are in Performance Enhancements.
lstat(FILEHANDLE) now gives a warning because the operation makes no sense.In future releases this may become a fatal error.
Spurious syntax errors generated in certain situations, when glob()caused File::Glob to be loaded for the first time, have been fixed. [561]
Lvalue subroutines can now return undef in list context. However,the lvalue subroutine feature still remains experimental. [561+]
A lost warning "Can't declare ... dereference in my" has beenrestored (Perl had it earlier but it became lost in later releases.)
A new special regular expression variable has been introduced:$^N, which contains the most-recently closed group (submatch).
no Module; does not produce an error even if Module does not have anunimport() method. This parallels the behavior of use vis-a-visimport. [561]
The numerical comparison operators return undef if either operandis a NaN. Previously the behaviour was unspecified.
our can now have an experimental optional attribute unique thataffects how global variables are shared among multiple interpreters,see our.
The following builtin functions are now overridable: each(), keys(),pop(), push(), shift(), splice(), unshift(). [561]
pack() / unpack() can now group template letters with () and thenapply repetition/count modifiers on the groups.
pack() / unpack() can now process the Perl internal numeric types:IVs, UVs, NVs-- and also long doubles, if supported by the platform.The template letters are j, J, F, and D.
pack('U0a*', ...) can now be used to force a string to UTF-8.
my __PACKAGE__ $obj now works. [561]
POSIX::sleep() now returns the number of unslept seconds(as the POSIX standard says), as opposed to CORE::sleep() whichreturns the number of slept seconds.
printf() and sprintf() now support parameter reordering using the%\d+\$ and *\d+\$ syntaxes. For example
```
 printf "%2\$s %1\$s\n", "foo", "bar";
 
```
will print "bar foo\n". This feature helps in writinginternationalised software, and in general when the orderof the parameters can vary.
The (\&) prototype now works properly. [561]
prototype(\[$@%&]) is now available to implicitly create references(useful for example if you want to emulate the tie() interface).
A new command-line option, -t is available. It is thelittle brother of -T: instead of dying on taint violations,lexical warnings are given. This is only meant as a temporarydebugging aid while securing the code of old legacy applications.This is not a substitute for -T.
In other taint news, the exec LIST and system LIST have now beenconsidered too risky (think exec @ARGV: it can start any programwith any arguments), and now the said forms cause a warning underlexical warnings. You should carefully launder the arguments toguarantee their validity. In future releases of Perl the forms willbecome fatal errors so consider starting laundering now.
Tied hash interfaces are now required to have the EXISTS and DELETEmethods (either own or inherited).
If tr/// is just counting characters, it doesn't attempt tomodify its target.
untie() will now call an UNTIE() hook if it exists. See perltiefor details. [561]
utime now supports utime undef, undef, @files to change thefile timestamps to the current time.
The rules for allowing underscores (underbars) in numeric constantshave been relaxed and simplified: now you can have an underscoresimply between digits.
Rather than relying on C's argv[0] (which may not contain a full pathname)where possible $^X is now set by asking the operating system.(eg by reading /proc/self/exe on Linux, /proc/curproc/file on FreeBSD)
A new variable, ${^TAINT}, indicates whether taint mode is enabled.
You can now override the readline() builtin, and this overrides alsothe <FILEHANDLE> angle bracket operator.
The command-line options -s and -F are now recognized on the shebang(#!) line.
Use of the /c match modifier without an accompanying /g modifierelicits a new warning: Use of /c modifier is meaningless without /g.
Use of /c in substitutions, even with /g, elicitsUse of /c modifier is meaningless in s///.
Use of /g with split elicits Use of /g modifier is meaninglessin split.
Support for the CLONE special subroutine had been added.With ithreads, when a new thread is created, all Perl data is cloned,however non-Perl data cannot be cloned automatically. In CLONE youcan do whatever you need to do, like for example handle the cloning ofnon-Perl data, if necessary. CLONE will be executed once for everypackage that has it defined or inherited. It will be called in thecontext of the new thread, so all modifications are made in the new area.
See perlmod

Modules and Pragmata

New Modules and Pragmata

Attribute::Handlers, originally by Damian Conway and now maintainedby Arthur Bergman, 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 canbe specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to theexact compilation phase (BEGIN, CHECK, INIT, or END).See Attribute::Handlers.
B::Concise, by Stephen McCamant, is a new compiler backend forwalking the Perl syntax tree, printing concise info about ops.The output is highly customisable. See B::Concise. [561+]
The new bignum, bigint, and bigrat pragmas, by Tels, implementtransparent bignum support (using the Math::BigInt, Math::BigFloat,and Math::BigRat backends).
Class::ISA, by Sean Burke, is a module for reporting the searchpath for a class's ISA tree. See Class::ISA.
Cwd now has a split personality: if possible, an XS extension isused, (this will hopefully be faster, more secure, and more robust)but if not possible, the familiar Perl implementation is used.
Devel::PPPort, originally by Kenneth Albanowski and nowmaintained by Paul Marquess, has been added. It is primarily usedby h2xs to enhance portability of XS modules between differentversions of Perl. See Devel::PPPort.
Digest, frontend module for calculating digests (checksums), fromGisle Aas, has been added. See Digest.
Digest::MD5 for calculating MD5 digests (checksums) as defined inRFC 1321, from Gisle Aas, has been added. See Digest::MD5.
```
 use Digest::MD5 'md5_hex';
 
  $digest = md5_hex("Thirsty Camel");
 
  print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
 
```
NOTE: the MD5 backward compatibility module is deliberately notincluded since its further use is discouraged.
See also PerlIO::via::QuotedPrint.
Encode, originally by Nick Ing-Simmons and now maintained by DanKogai, provides a mechanism to translate between different characterencodings. Support for Unicode, ISO-8859-1, and ASCII are compiled into the module. Several other encodings (like the rest of theISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese,Japanese, and Korean encodings) are included and can be loaded atruntime. (For space considerations, the largest Chinese encodingshave been separated into their own CPAN module, Encode::HanExtra,which Encode will use if available). See Encode.
Any encoding supported by Encode module is also available to the":encoding()" layer if PerlIO is used.
Hash::Util is the interface to the new restricted hashesfeature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, andMichael Schwern.) See Hash::Util.
I18N::Langinfo can be used to query locale information.See I18N::Langinfo.
I18N::LangTags, by Sean Burke, has functions for dealing withRFC3066-style language tags. See I18N::LangTags.
ExtUtils::Constant, by Nicholas Clark, is a new tool for extensionwriters for generating XS code to import C header constants.See ExtUtils::Constant.

Filter::Simple, by Damian Conway, is an easy-to-use frontend toFilter::Util::Call. See Filter::Simple.

 # 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"

File::Temp, by Tim Jenness, allows one to create temporary filesand directories in an easy, portable, and secure way. See File::Temp.[561+]
Filter::Util::Call, by Paul Marquess, provides you with theframework to write source filters in Perl. For most uses, thefrontend Filter::Simple is to be preferred. See Filter::Util::Call.
if, by Ilya Zakharevich, is a new pragma for conditional inclusionof modules.
libnet, by Graham Barr, is a collection of perl5 modules relatedto network programming. See Net::FTP, Net::NNTP, Net::Ping(not part of libnet, but related), Net::POP3, Net::SMTP,and Net::Time.
Perl installation leaves libnet unconfigured; use libnetcfgto configure it.
List::Util, by Graham Barr, is a selection of general-utilitylist subroutines, such as sum(), min(), first(), and shuffle().See List::Util.
Locale::Constants, Locale::Country, Locale::CurrencyLocale::Language, and Locale::Script, by Neil Bowers, havebeen added. They provide the codes for various locale standards, suchas "fr" for France, "usd" for US Dollar, and "ja" for Japanese.
```
 use Locale::Country;
 
  $country = code2country('jp');   # $country gets 'Japan'
  $code = country2code('Norway');   # $code gets 'no'
 
```
See Locale::Constants, Locale::Country, Locale::Currency,and Locale::Language.
Locale::Maketext, by Sean Burke, is a localization framework. SeeLocale::Maketext, and Locale::Maketext::TPJ13. The latter is anarticle about software localization, originally published in The PerlJournal #13, and republished here with kind permission.
Math::BigRat for big rational numbers, to accompany Math::BigInt andMath::BigFloat, from Tels. See Math::BigRat.
Memoize can make your functions faster by trading space for time,from Mark-Jason Dominus. See Memoize.

MIME::Base64, by Gisle Aas, allows you to encode data in base64,as defined in RFC 2045 - MIME (Multipurpose Internet MailExtensions).

 use MIME::Base64;
 
  $encoded = encode_base64('Aladdin:open sesame');
  $decoded = decode_base64($encoded);
 
  print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="

See MIME::Base64.

MIME::QuotedPrint, by Gisle Aas, allows you to encode datain quoted-printable encoding, as defined in RFC 2045 - MIME(Multipurpose Internet Mail Extensions).

 use MIME::QuotedPrint;
 
  $encoded = encode_qp("\xDE\xAD\xBE\xEF");
  $decoded = decode_qp($encoded);
 
  print $encoded, "\n"; # "=DE=AD=BE=EF\n"
  print $decoded, "\n"; # "\xDE\xAD\xBE\xEF\n"

Updated And Improved Modules and Pragmata

The following independently supported modules have been updated to thenewest 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 [561+], Pod::Parser, Storable,Term::ANSIColor, Test, Text-Tabs+Wrap.
attributes::reftype() now works on tied arguments.
AutoLoader can now be disabled with no AutoLoader;.
B::Deparse has been significantly enhanced by Robin Houston. It cannow deparse almost all of the standard test suite (so that the testsstill succeed). There is a make target "test.deparse" for trying thisout.
Carp now has better interface documentation, and the @CARP_NOTinterface has been added to get optional control over where errorsare reported independently of @ISA, by Ben Tilly.
Class::Struct can now define the classes in compile time.
Class::Struct now assigns the array/hash element if the accessoris called with an array/hash element as the sole argument.
The return value of Cwd::fastcwd() is now tainted.
Data::Dumper now has an option to sort hashes.
Data::Dumper now has an option to dump code referencesusing B::Deparse.
DB_File now supports newer Berkeley DB versions, amongother improvements.
Devel::Peek now has an interface for the Perl memory statistics(this works only if you are using perl's malloc, and if you havecompiled with debugging).
The English module can now be used without the infamous performancehit by saying
```
use English '-no_match_vars';
 
```
(Assuming, of course, that you don't need the troublesome variables$`, $&, or $'.) Also, introduced @LAST_MATCH_START and@LAST_MATCH_END English aliases for @- and @+.
ExtUtils::MakeMaker has been significantly cleaned up and fixed.The enhanced version has also been backported to earlier releasesof Perl and submitted to CPAN so that the earlier releases canenjoy the fixes.
The arguments of WriteMakefile() in Makefile.PL are now checkedfor sanity much more carefully than before. This may cause newwarnings when modules are being installed. See ExtUtils::MakeMakerfor more details.
ExtUtils::MakeMaker now uses File::Spec internally, which hopefullyleads to better portability.
Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clarkto use the new-style constant dispatch section (see ExtUtils::Constant).This means that they will be more robust and hopefully faster.
File::Find now chdir()s correctly when chasing symbolic links. [561]
File::Find now has pre- and post-processing callbacks. It alsocorrectly changes directories when chasing symbolic links. Callbacks(naughtily) exiting with "next;" instead of "return;" now work.
File::Find is now (again) reentrant. It also has been mademore portable.
The warnings issued by File::Find now belong to their own category.You can enable/disable them with use/no warnings 'File::Find';.
File::Glob::glob() has been renamed to File::Glob::bsd_glob()because the name clashes with the builtin glob(). The oldername is still available for compatibility, but is deprecated. [561]
File::Glob now supports GLOB_LIMIT constant to limit the size ofthe returned list of filenames.
IPC::Open3 now allows the use of numeric file descriptors.
IO::Socket now has an atmark() method, which returns true if the socketis positioned at the out-of-band mark. The method is also exportableas a sockatmark() function.
IO::Socket::INET failed to open the specified port if the service namewas not known. It now correctly uses the supplied port number as is. [561]
IO::Socket::INET has support for the ReusePort option (if yourplatform supports it). The Reuse option now has an alias, ReuseAddr.For clarity, you may want to prefer ReuseAddr.
IO::Socket::INET now supports a value of zero for LocalPort(usually meaning that the operating system will make one up.)
'use lib' now works identically to @INC. Removing directorieswith 'no lib' now works.
Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels.They are now magnitudes faster, and they support various bignumlibraries such as GMP and PARI as their backends.
Math::Complex handles inf, NaN etc., better.
Net::Ping has been considerably enhanced by Rob Brown: multihoming isnow supported, Win32 functionality is better, there is now timemeasuring functionality (optionally high-resolution usingTime::HiRes), and there is now "external" protocol which usesNet::Ping::External module which runs your external ping utility andparses the output. A version of Net::Ping::External is available inCPAN.
Note that some of the Net::Ping tests are disabled when runningunder the Perl distribution since one cannot assume one or moreof the following: enabled echo port at localhost, full Internetconnectivity, or sympathetic firewalls. You can set the environmentvariable PERL_TEST_Net_Ping to "1" (one) before running the Perl testsuite to enable all the Net::Ping tests.
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.
In Safe, %INC is now localised in a Safe compartment so thatuse/require work.
In SDBM_File on dosish platforms, some keys went missing because oflack of support for files with "holes". A workaround for the problemhas been added.
In Search::Dict one can now have a pre-processing hook for thelines being searched.
The Shell module now has an OO interface.
In Sys::Syslog there is now a failover mechanism that will gothrough alternative connection mechanisms until the messageis successfully logged.
The Test module has been significantly enhanced.
Time::Local::timelocal() does not handle fractional seconds anymore.The rationale is that neither does localtime(), and timelocal() andlocaltime() are supposed to be inverses of each other.
The vars pragma now supports declaring fully qualified variables.(Something that our() does not and will not support.)
The utf8:: name space (as in the pragma) provides variousPerl-callable functions to provide low level access to Perl'sinternal Unicode representation. At the moment only length()has been implemented.

Utility Changes

Emacs perl mode (emacs/cperl-mode.el) has been updated to version4.31.
emacs/e2ctags.pl is now much faster.
enc2xs is a tool for people adding their own encodings to theEncode module.
h2ph now supports C trigraphs.
h2xs now produces a template README.
h2xs now uses Devel::PPPort for better portability betweendifferent versions of Perl.
h2xs uses the new ExtUtils::Constant modulewhich will affect newly created extensions that define constants.Since the new code is more correct (if you have two constants where thefirst one is a prefix of the second one, the first constant nevergot defined), less lossy (it uses integers for integer constant,as opposed to the old code that used floating point numbers even forinteger constants), and slightly faster, you might want to considerregenerating your extension code (the new scheme makes regeneratingeasy). h2xs now also supports C trigraphs.
libnetcfg has been added to configure libnet.
perlbug is now much more robust. It also sends the bug report toperl.org, not perl.com.
perlcc 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 perlcc -B instead.)Note that perlcc is still considered very experimental andunsupported. [561]
perlivp is a new Installation Verification Procedure utilityfor running any time after installing Perl.
piconv is an implementation of the character conversion utilityiconv, demonstrating the new Encode module.
pod2html now allows specifying a cache directory.
pod2html now produces XHTML 1.0.
pod2html now understands POD written using different line endings(PC-like CRLF versus Unix-like LF versus MacClassic-like CR).
s2p has been completely rewritten in Perl. (It is in fact a fullimplementation of sed in Perl: you can use the sed functionality byusing the psed utility.)
xsubpp now understands POD documentation embedded in the *.xsfiles. [561]
xsubpp now supports the OUT keyword.

New Documentation

perl56delta details the changes between the 5.005 release and the5.6.0 release.
perlclib documents the internal replacements for standard C libraryfunctions. (Interesting only for extension writers and Perl corehackers.) [561+]
perldebtut is a Perl debugging tutorial. [561+]
perlebcdic contains considerations for running Perl on EBCDICplatforms. [561+]
perlintro is a gentle introduction to Perl.
perliol documents the internals of PerlIO with layers.
perlmodstyle is a style guide for writing modules.
perlnewmod tells about writing and submitting a new module. [561+]
perlpacktut is a pack() tutorial.
perlpod has been rewritten to be clearer and to record the bestpractices gathered over the years.
perlpodspec is a more formal specification of the pod format,mainly of interest for writers of pod applications, not topeople writing in pod.
perlretut is a regular expression tutorial. [561+]
perlrequick is a regular expressions quick-start guide.Yes, much quicker than perlretut. [561]
perltodo has been updated.
perltootc has been renamed as perltooc (to not to conflictwith perltoot in filesystems restricted to "8.3" names).
perluniintro is an introduction to using Unicode in Perl.(perlunicode is more of a detailed reference and backgroundinformation)
perlutil explains the command line utilities packaged with the Perldistribution. [561+]

The following platform-specific documents are available beforethe installation as README.platform, and after the installationas perlplatform:

 perlaix perlamiga perlapollo perlbeos perlbs2000
  perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux
  perlhurd perlirix perlmachten perlmacos perlmint perlmpeix
  perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
  perltru64 perluts perlvmesa perlvms perlvos perlwin32

These documents usually detail one or more of the following subjects:configuring, building, testing, installing, and sometimes also usingPerl on the said platform.

Eastern Asian Perl users are now welcomed in their own languages:README.jp (Japanese), README.ko (Korean), README.cn (simplifiedChinese) and README.tw (traditional Chinese), which are written innormal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. Thesewill get installed as

   perljp perlko perlcn perltw

The documentation for the POSIX-BC platform is called "BS2000", to avoidconfusion with the Perl POSIX module.
The documentation for the WinCE platform is called perlce (README.cein the source code kit), to avoid confusion with the perlwin32documentation on 8.3-restricted filesystems.

Performance Enhancements

map() could get pathologically slow when the result list it generatesis larger than the source list. The performance has been improved forcommon scenarios. [561]
sort() is also fully reentrant, in the sense that the sort functioncan itself call sort(). This did not work reliably in previousreleases. [561]
sort() has been changed to use primarily mergesort internally asopposed to the earlier quicksort. For very small lists this mayresult in slightly slower sorting times, but in general the speedupshould be at least 20%. Additional bonuses are that the worst casebehaviour of sort() is now better (in computer science terms it nowruns 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 theywere before the sort). See the sort pragma for information.
The story in more detail: suppose you want to serve yourself a littleslice 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 1 comes first is hard to know, since one 1 looks prettymuch like any other. You can regard this as totally trivial,or somewhat profound. However, if you just want to sort the evendigits ahead of the odd ones, then what will
```
 sort { ($a % 2) <=> ($b % 2) } @digits;
 
```
yield? The only even digit, 4, will come first. But how aboutthe odd numbers, which all compare equal? With the quicksort algorithmused to implement Perl 5.6 and earlier, the order of ties is left upto the sort. So, as you add more and more digits of Pi, the orderin which the sorted even and odd digits appear will change.and, for sufficiently large slices of Pi, the quicksort algorithmin Perl 5.8 won't return the same results even if reinvoked with thesame input. The justification for this rests with quicksort'sworst case behavior. If you run
```
   sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
 
```
(something you might approximate if you wanted to merge two sortedarrays using sort), doubling $N doesn't just double the quicksort time,it quadruples it. Quicksort has a worst case run time that cangrow like N**2, so-called quadratic behaviour, and it can happenon patterns that may well arise in normal use. You won't notice thisfor small arrays, but you will notice it with larger arrays,and you may not live long enough for the sort to complete on arraysof a million elements. So the 5.8 quicksort scrambles large arraysbefore sorting them, as a statistical defence against quadratic behaviour.But that means if you sort the same large array twice, ties may bebroken in different ways.
Because of the unpredictability of tie-breaking order, and the quadraticworst-case behaviour, quicksort was almost replaced completely witha stable mergesort. Stable means that ties are broken to preservethe original order of appearance in the input array. So
```
 sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
 
```
will yield (4,3,1,1,5,9), guaranteed. The even and odd numbersappear in the output in the same order they appeared in the input.Mergesort has worst case O(N log N) behaviour, the best valueattainable. And, ironically, this mergesort does particularlywell where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)in O(N) time. But quicksort was rescued at the last moment becauseit is faster than mergesort on certain inputs and platforms.For example, if you really don't care about the order of evenand odd digits, quicksort will run in O(N) time; it's very goodat sorting many repetitions of a small number of distinct elements.The quicksort divide and conquer strategy works well on platformswith relatively small, very fast, caches. Eventually, the problem getswhittled down to one that fits in the cache, from which point itbenefits from the increased memory speed.
Quicksort was rescued by implementing a sort pragma to control aspectsof the sort. The stable subpragma forces stable behaviour,regardless of algorithm. The _quicksort and _mergesortsubpragmas are heavy-handed ways to select the underlying implementation.The leading _ is a reminder that these subpragmas may not survivebeyond 5.8. More appropriate mechanisms for selecting the implementationexist, but they wouldn't have arrived in time to save quicksort.
Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm isreasonably fast while producing a much better spread of values thanthe old hashing algorithm (originally by Chris Torek, later tweaked byIlya Zakharevich). Hash values output from the algorithm on a hash ofall 3-char printable ASCII keys comes much closer to passing theDIEHARD random number generation tests. According to perlbench, thischange has not affected the overall speed of Perl.
unshift() should now be noticeably faster.

Installation and Configuration Improvements

Generic Improvements

INSTALL now explains how you can configure Perl to use 64-bitintegers even on non-64-bit platforms.
Policy.sh policy change: if you are reusing a Policy.sh file(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the oldPolicy $prefix eq $siteprefix and $prefix eq $vendorprefix, all ofthem will now be changed to the new prefix, /foo/bar. (Previouslyonly $prefix changed.) If you do not like this new behaviour,specify prefix, siteprefix, and vendorprefix explicitly.
A new optional location for Perl libraries, otherlibdirs, is available.It can be used for example for vendor add-ons without disturbing Perl'sown library directories.
In many platforms, the vendor-supplied 'cc' is too stripped-down tobuild Perl (basically, 'cc' doesn't do ANSI C). If this seemsto 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.
gcc needs to closely track the operating system release to avoidbuild problems. If Configure finds that gcc was built for a differentoperating system release than is running, it now gives a clearly visiblewarning that there may be trouble ahead.
Since Perl 5.8 is not binary-compatible with previous releasesof Perl, Configure no longer suggests including the 5.005modules in @INC.
Configure -S can now run non-interactively. [561]
Configure support for pdp11-style memory models has been removed dueto obsolescence. [561]
configure.gnu now works with options with whitespace in them.
installperl now outputs everything to STDERR.
Because PerlIO is now the default on most platforms, "-perlio" doesn'tget appended to the $Config{archname} (also known as $^O) anymore.Instead, if you explicitly choose not to use perlio (Configure commandline option -Uuseperlio), you will get "-stdio" appended.
Another change related to the architecture name is that "-64all"(-Duse64bitall, or "maximally 64-bit") is appended only if yourpointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
In AFS installations, one can configure the root of the AFS to besomewhere else than the default /afs by using the Configureparameter -Dafsroot=/some/where/else.
APPLLIB_EXP, a lesser-known configuration-time definition, has beendocumented. It can be used to prepend site-specific directoriesto Perl's default search path (@INC); see INSTALL for information.
The version of Berkeley DB used when the Perl (and, presumably, theDB_File extension) was built is now available as@Config{qw(db_version_major db_version_minor db_version_patch)}from Perl and as DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFGDB_VERSION_PATCH_CFG from C.
Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBMhas been documented in INSTALL.
If you have CPAN access (either network or a local copy such as aCD-ROM) you can during specify extra modules to Configure to build andinstall with Perl using the -Dextras=... option. See INSTALL formore details.
In addition to config.over, a new override file, config.arch, isavailable. This file is supposed to be used by hints file writersfor architecture-wide changes (as opposed to config.over which isfor site-wide changes).
If your file system supports symbolic links, you can build Perl outsideof the source directory by
```
mkdir perl/build/directory
 cd perl/build/directory
 sh /path/to/perl/source/Configure -Dmksymlinks ...
 
```
This will create in perl/build/directory a tree of symbolic linkspointing to files in /path/to/perl/source. The original files are leftunaffected. After Configure has finished, you can just say
```
make all test
 
```
and Perl will be built and tested, all in perl/build/directory.[561]
For Perl developers, several new make targets for profilingand debugging have been added; see perlhack.
- Use of the gprof tool to profile Perl has been documented inperlhack. There is a make target called "perl.gprof" forgenerating a gprofiled Perl executable.
- If you have GCC 3, there is a make target called "perl.gcov" forcreating a gcoved Perl executable for coverage analysis. Seeperlhack.
- If you are on IRIX or Tru64 platforms, new profiling/debugging optionshave been added; see perlhack for more information about pixie andThird Degree.
Guidelines of how to construct minimal Perl installations havebeen added to INSTALL.
The Thread extension is now not built at all under ithreads(Configure -Duseithreads) because it wouldn't work anyway (theThread extension requires being Configured with -Duse5005threads).
Note that the 5.005 threads are unsupported and deprecated: if youhave code written for the old threads you should migrate it to thenew ithreads model.
The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifyingfloating-point numbers is now more picky about using sprintf %.*grules for the conversion. Some platforms that used to use gcvt maynow resort to the slower sprintf.
The obsolete method of making a special (e.g., debugging) flavorof perl by saying
```
make LIBPERL=libperld.a
 
```
has been removed. Use -DDEBUGGING instead.

New Or Improved Platforms

For the list of platforms known to support Perl,see Supported Platforms in perlport.

AIX dynamic loading should be now better supported.
AIX should now work better with gcc, threads, and 64-bitness. Also thelong doubles support in AIX should be better now. See perlaix.
AtheOS ( http://www.atheos.cx/ ) is a new platform.
BeOS has been reclaimed.
The DG/UX platform now supports 5.005-style threads.See perldgux.
The DYNIX/ptx platform (also known as dynixptx) is supported at ornear osvers 4.5.2.
EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA)have been regained. Many test suite tests still fail and theco-existence of Unicode and EBCDIC isn't quite settled, but thesituation is much better than with Perl 5.6. See perlos390,perlbs2000 (for POSIX-BC), and perlvmesa for more information.
Building perl with -Duseithreads or -Duse5005threads now works underHP-UX 10.20 (previously it only worked under 10.30 or later). You willneed a thread library package installed. See README.hpux. [561]
Mac OS Classic is now supported in the mainstream source package(MacPerl has of course been available since perl 5.004 but now thesource code bases of standard Perl and MacPerl have been synchronised)[561]
Mac OS X (or Darwin) should now be able to build Perl even on HFS+filesystems. (The case-insensitivity used to confuse the Perl buildprocess.)
NCR MP-RAS is now supported. [561]
All the NetBSD specific patches (except for the installationspecific ones) have been merged back to the main distribution.
NetWare from Novell is now supported. See perlnetware.
NonStop-UX is now supported. [561]
NEC SUPER-UX is now supported.
All the OpenBSD specific patches (except for the installationspecific ones) have been merged back to the main distribution.
Perl has been tested with the GNU pth userlevel thread package( http://www.gnu.org/software/pth/pth.html ). All thread testsof Perl now work, but not without adding some yield()s to the tests,so while pth (and other userlevel thread implementations) can beconsidered to be "working" with Perl ithreads, keep in mind thepossible non-preemptability of the underlying thread implementation.
Stratus VOS is now supported using Perl's native build method(Configure). This is the recommended method to build Perl onVOS. The older methods, which build miniperl, are stillavailable. See perlvos. [561+]
The Amdahl UTS Unix mainframe platform is now supported. [561]
WinCE is now supported. See perlce.
z/OS (formerly known as OS/390, formerly known as MVS OE) now hassupport for dynamic loading. This is not selected by default,however, you must specify -Dusedl in the arguments of Configure. [561]

Selected Bug Fixes

Numerous memory leaks and uninitialized memory accesses have beenhunted down. Most importantly, anonymous subs used to leak quitea bit. [561]

The autouse pragma didn't work for Multi::Part::Function::Names.
caller() could cause core dumps in certain situations. Carp wassometimes affected by this problem. In particular, caller() nowreturns a subroutine name of (unknown) for subroutines that havebeen removed from the symbol table.
chop(@list) in list context returned the characters chopped inreverse order. This has been reversed to be in the right order. [561]
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. [561]
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). Thiswas caused by Perl's using the operating system libraries in a situationwhere the result of the string to number conversion is undefined: nowPerl consistently handles such strings as zero in numeric contexts.
Several debugger fixes: exit code now reflects the script exit code,condition "0" now treated correctly, the d command now checksline number, $. no longer gets corrupted, and all debugger outputnow goes correctly to the socket if RemotePort is set. [561]
The debugger (perl5db.pl) has been modified to present a moreconsistent commands interface, via (CommandSet=580). perl5db.t wasalso added to test the changes, and as a placeholder for further tests.
See perldebug.
The debugger has a new dumpDepth option to control the maximumdepth to which nested structures are dumped. The x command hasbeen extended so that x N EXPR dumps out the value of EXPR to adepth of at most N levels.
The debugger can now show lexical variables if you have the CPANmodule PadWalker installed.
The order of DESTROYs has been made more predictable.
Perl 5.6.0 could emit spurious warnings about redefinition ofdl_error() when statically building extensions into perl.This has been corrected. [561]
dprofpp -R didn't work.
*foo{FORMAT} now works.
Infinity is now recognized as a number.
UNIVERSAL::isa no longer caches methods incorrectly. (This brokethe Tk extension with 5.6.0.) [561]
Lexicals I: lexicals outside an eval "" weren't resolvedcorrectly inside a subroutine definition inside the eval "" if theywere not already referenced in the top level of the eval""ed code.
Lexicals II: lexicals leaked at file scope into subroutines thatwere declared before the lexicals.
Lexical warnings now propagating correctly between scopesand into eval "...".
use warnings qw(FATAL all) did not work as intended. This has beencorrected. [561]
warnings::enabled() now reports the state of $^W correctly if the callerisn't using lexical warnings. [561]
Line renumbering with eval and #line now works. [561]
Fixed numerous memory leaks, especially in eval "".

Localised tied variables no longer leak memory

 use Tie::Hash;
  tie my %tied_hash => 'Tie::StdHash';
 
  ...
 
  # Used to leak memory every time local() was called;
  # in a loop, this added up.
  local($tied_hash{Foo}) = 1;

Localised hash elements (and %ENV) are correctly unlocalised to notexist, if they didn't before they were localised.

 use Tie::Hash;
  tie my %tied_hash => 'Tie::StdHash';
 
  ...
 
  # Nothing has set the FOO element so far
 
  { local $tied_hash{FOO} = 'Bar' }
 
  # This used to print, but not now.
  print "exists!\n" if exists $tied_hash{FOO};

As a side effect of this fix, tied hash interfaces must definethe EXISTS and DELETE methods.

mkdir() now ignores trailing slashes in the directory name,as mandated by POSIX.
Some versions of glibc have a broken modfl(). This affects buildswith -Duselongdouble. This version of Perl detects this brokennessand has a workaround for it. The glibc release 2.2.2 is known to havefixed the modfl() bug.
Modulus of unsigned numbers now works (4063328477 % 65535 used toreturn 27406, instead of 27047). [561]
Some "not a number" warnings introduced in 5.6.0 eliminated to bemore compatible with 5.005. Infinity is now recognised as a number. [561]
Numeric conversions did not recognize changes in the string valueproperly in certain circumstances. [561]
Attributes (such as :shared) didn't work with our().
our() variables will not cause bogus "Variable will not stay shared"warnings. [561]
"our" variables of the same name declared in two sibling blocksresulted in bogus warnings about "redeclaration" of the variables.The problem has been corrected. [561]
pack "Z" now correctly terminates the string with "\0".
Fix password routines which in some shadow password platforms(e.g. HP-UX) caused getpwent() to return every other entry.
The PERL5OPT environment variable (for passing command line argumentsto Perl) didn't work for more than a single group of options. [561]
PERL5OPT with embedded spaces didn't work.
printf() no longer resets the numeric locale to "C".
qw(a\b) now parses correctly as 'a\b': that is, as threecharacters, not four. [561]
pos() did not return the correct value within s///ge in earlierversions. This is now handled correctly. [561]
Printing quads (64-bit integers) with printf/sprintf now workswithout the q L ll prefixes (assuming you are on a quad-capable platform).
Regular expressions on references and overloaded scalars now work. [561+]
Right-hand side magic (GMAGIC) could in many cases such as stringconcatenation be invoked too many times.
scalar() now forces scalar context even when used in void context.
SOCKS support is now much more robust.
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 argumentsto be sorted are always provided list context. [561]
Changed the POSIX character class [[:space:]] to include the (veryrarely used) vertical tab character. Added a new POSIX-ish characterclass [[:blank:]] which stands for horizontal whitespace(currently, the space and the tab).
The tainting behaviour of sprintf() has been rationalized. It doesnot taint the result of floating point formats anymore, making thebehaviour consistent with that of string interpolation. [561]
Some cases of inconsistent taint propagation (such as within hashvalues) have been fixed.
The RE engine found in Perl 5.6.0 accidentally pessimised certain kindsof simple pattern matches. These are now handled better. [561]
Regular expression debug output (whether through use re 'debug'or via -Dr) now looks better. [561]
Multi-line matches like "a\nxb\n" =~ /(?!\A)x/m were flawed. Thebug has been fixed. [561]
Use of $& could trigger a core dump under some situations. Thisis now avoided. [561]
The regular expression captured submatches ($1, $2, ...) are nowmore consistently unset if the match fails, instead of leaving falsedata lying around in them. [561]
readline() on files opened in "slurp" mode could return an extra"" (blank line) at the end in certain situations. This has beencorrected. [561]
Autovivification of symbolic references of special variables describedin perlvar (as in ${$num}) was accidentally disabled. This worksagain now. [561]
Sys::Syslog ignored the LOG_AUTH constant.
$AUTOLOAD, sort(), lock(), and spawning subprocessesin multiple threads simultaneously are now thread-safe.
Tie::Array's SPLICE method was broken.
Allow a read-only string on the left-hand side of a non-modifying tr///.
If STDERR is tied, warnings caused by warn and die nowcorrectly pass to it.
Several Unicode fixes.
- BOMs (byte order marks) at the beginning of Perl files(scripts, modules) should now be transparently skipped.UTF-16 and UCS-2 encoded Perl files should now be read correctly.
- The character tables have been updated to Unicode 3.2.0.
- Comparing with utf8 data does not magically upgrade non-utf8 datainto utf8. (This was a problem for example if you were mixing datafrom I/O and Unicode data: your output might have got magically encodedas UTF-8.)
- Generating illegal Unicode code points such as U+FFFE, or the UTF-16surrogates, now also generates an optional warning.
- IsAlnum, IsAlpha, and IsWord now match titlecase.
- Concatenation with the . operator or via variable interpolation,eq, substr, reverse, quotemeta, the x operator,substitution with s///, single-quoted UTF-8, should now work.
- The tr/// operator now works. Note that the tr///CUfunctionality has been removed (but see pack('U0', ...)).
- eval "v200" now works.
- Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.This has been corrected. [561]
- Zero entries were missing from the Unicode classes such as IsDigit.
Large unsigned numbers (those above 2**31) could sometimes lose theirunsignedness, causing bogus results in arithmetic operations. [561]
The Perl parser has been stress tested using both random input andMarkov chain input and the few found crashes and lockups have beenfixed.

Platform Specific Changes and Fixes

BSDI 4.*
Perl now works on post-4.0 BSD/OSes.
All BSDs
Setting $0 now works (as much as possible; see perlvar for details).
Cygwin
Numerous updates; currently synchronised with Cygwin 1.3.10.
Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
EPOC
EPOC now better supported. See README.epoc. [561]
FreeBSD 3.*
Perl now works on post-3.0 FreeBSDs.
HP-UX
README.hpux updated; Configure -Duse64bitall now works;now uses HP-UX malloc instead of Perl malloc.
IRIX
Numerous compilation flag and hint enhancements; accidental mixingof 32-bit and 64-bit libraries (a doomed attempt) made much harder.
Linux
- Long doubles should now work (see INSTALL). [561]
- Linux previously had problems related to sockaddrlen when usingaccept(), recvfrom() (in Perl: recv()), getpeername(), andgetsockname().
Mac OS Classic
Compilation of the standard Perl distribution in Mac OS Classic shouldnow work if you have the Metrowerks development environment and themissing Mac-specific toolkit bits. Contact the macperl mailing listfor details.
MPE/iX
MPE/iX update after Perl 5.6.0. See README.mpeix. [561]
NetBSD/threads: try installing the GNU pth (should be in thepackages collection, or http://www.gnu.org/software/pth/),and Configure with -Duseithreads.
NetBSD/sparc
Perl now works on NetBSD/sparc.
OS/2
Now works with usethreads (see INSTALL). [561]
Solaris
64-bitness using the Sun Workshop compiler now works.
Stratus VOS
The native build method requires at least VOS Release 14.5.0and GNU C++/GNU Tools 2.0.1 or later. The Perl pack functionnow maps overflowed values to +infinity and underflowed valuesto -infinity.
Tru64 (aka Digital UNIX, aka DEC OSF/1)
The operating system version letter now recorded in $Config{osvers}.Allow compiling with gcc (previously explicitly forbidden). Compilingwith gcc still not recommended because buggy code results, even withgcc 2.95.2.
Unicos
Fixed various alignment problems that lead into core dumps eitherduring build or later; no longer dies on math errors at runtime;now using full quad integers (64 bits), previously was usingonly 46 bit integers for speed.
VMS
See Socket Extension Dynamic in VMS and IEEE-format Floating Point Default on OpenVMS Alpha for important changes not otherwise listed here.
chdir() now works better despite a CRT bug; now works with MULTIPLICITY(see INSTALL); now works with Perl's malloc.
The tainting of %ENV elements via keys or values was previouslyunimplemented. It now works as documented.
The waitpid emulation has been improved. The worst bug (now fixed)was that a pid of -1 would cause a wildcard search of all processes onthe system.
POSIX-style signals are now emulated much better on VMS versions priorto 7.0.
The system function and backticks operator have improvedfunctionality and better error handling. [561]
File access tests now use current process privileges rather than theuser's default privileges, which could sometimes result in a mismatchbetween reported access and actual access. This improvement is onlyavailable on VMS v6.0 and later.
There is a new kill implementation based on sys$sigprc that allowsolder VMS systems (pre-7.0) to use kill to send signals rather thansimply force exit. This implementation also allows later systems tocall kill from within a signal handler.
Iterative logical name translations are now limited to 10 iterations inimitation of SHOW LOGICAL and other OpenVMS facilities.
Windows
- Signal handling now works better than it used to. It is now implementedusing a Windows message loop, and is therefore less prone to randomcrashes.
- fork() emulation is now more robust, but still continues to have a fewesoteric bugs and caveats. See perlfork for details. [561+]
- A failed (pseudo)fork now returns undef and sets errno to EAGAIN. [561]
- The following modules now work on Windows:
```
 ExtUtils::Embed [561]
  IO::Pipe
  IO::Poll
  Net::Ping
 
```
- IO::File::new_tmpfile() is no longer limited to 32767 invocationsper-process.
- Better chdir() return value for a non-existent directory.
- Compiling perl using the 64-bit Platform SDK tools is now supported.
- The Win32::SetChildShowWindow() builtin can be used to control thevisibility of windows created by child processes. See Win32 fordetails.
- Non-blocking waits for child processes (or pseudo-processes) aresupported via waitpid($pid, &POSIX::WNOHANG).
- The behavior of system() with multiple arguments has been rationalized.Each unquoted argument will be automatically quoted to protect whitespace,and any existing whitespace in the arguments will be preserved. Thisimproves the portability of system(@args) by avoiding the need forWindows cmd shell specific quoting in perl programs.
  Note that this means that some scripts that may have relied on earlierbuggy behavior may no longer work correctly. For example,system("nmake /nologo", @args) will now attempt to run the filenmake /nologo and will fail when such a file isn't found.On the other hand, perl will now execute code such assystem("c:/Program Files/MyApp/foo.exe", @args) correctly.
- The perl header files no longer suppress common warnings from theMicrosoft Visual C++ compiler. This means that additional warnings maynow show up when compiling XS code.
- Borland C++ v5.5 is now a supported compiler that can build Perl.However, the generated binaries continue to be incompatible with thosegenerated by the other supported compilers (GCC and Visual C++). [561]
- Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.[561]
- Current directory entries in %ENV are now correctly propagated to childprocesses. [561]
- New %ENV entries now propagate to subprocesses. [561]
- Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.Other bugs in chdir() and Cwd::cwd() have also been fixed. [561]
- The makefiles now default to the features enabled in ActiveState ActivePerl(a popular Win32 binary distribution). [561]
- HTML files will now be installed in c:\perl\html instead ofc:\perl\lib\pod\html
- REG_EXPAND_SZ keys are now allowed in registry settings used by perl. [561]
- Can now send() from all threads, not just the first one. [561]
- ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries. [561]
- Less stack reserved per thread so that more threads can runconcurrently. (Still 16M per thread.) [561]
- File::Spec->tmpdir() now prefers C:/temp over /tmp(works better when perl is running as service).
- Better UNC path handling under ithreads. [561]
- wait(), waitpid(), and backticks now return the correct exit statusunder Windows 9x. [561]
- A socket handle leak in accept() has been fixed. [561]

New or Changed Diagnostics

Please see perldiag for more details.

Ambiguous range in the transliteration operator (like a-z-9) nowgives a warning.
chdir("") and chdir(undef) now give a deprecation warning because theycause a possible unintentional chdir to the home directory.Say chdir() if you really mean that.
Two new debugging options have been added: if you have compiled yourPerl with debugging, you can use the -DT [561] and -DR options to tracetokenising and to add reference counts to displaying variables,respectively.
The lexical warnings category "deprecated" is no longer a sub-categoryof the "syntax" category. It is now a top-level category in its ownright.
Unadorned dump() will now give a warning suggesting touse explicit CORE::dump() if that's what really is meant.
The "Unrecognized escape" warning has been extended to include \8,\9, and \_. There is no need to escape any of the \w characters.
All regular expression compilation error messages are now hopefullyeasier to understand both because the error message now comes beforethe failed regex and because the point of failure is now clearlymarked by a <-- HERE marker.
Various I/O (and socket) functions like binmode(), close(), and soforth now more consistently warn if they are used illogically eitheron a yet unopened or on an already closed filehandle (or socket).
Using lstat() on a filehandle now gives a warning. (It's a non-sensicalthing to do.)
The -M and -m options now warn if you didn't supply the module name.
If you in use specify a required minimum version, modules matchingthe name and but not defining a $VERSION will cause a fatal failure.
Using negative offset for vec() in lvalue context is now a warnable offense.
Odd number of arguments to overload::constant now elicits a warning.
Odd number of elements in anonymous hash now elicits a warning.
The various "opened only for", "on closed", "never opened" warningsdrop the main:: prefix for filehandles in the main package,for example STDIN instead of main::STDIN.
Subroutine prototypes are now checked more carefully, you mayget warnings for example if you have used non-prototype characters.
If an attempt to use a (non-blessed) reference as an array indexis made, a warning is given.
push @a; and unshift @a; (with no values to push or unshift)now give a warning. This may be a problem for generated and eval'edcode.
If you try to pack a number less than 0 or larger than 255using the "C" format you will get an optional warning. Similarlyfor the "c" format and a number less than -128 or more than 127.
pack P format now demands an explicit size.
unpack w now warns of unterminated compressed integers.
Warnings relating to the use of PerlIO have been added.
Certain regex modifiers such as (?o) make sense only if applied tothe entire regex. You will get an optional warning if you try to dootherwise.
Variable length lookbehind has not yet been implemented, trying touse it will tell that.
Using arrays or hashes as references (e.g. %foo->{bar}has been deprecated for a while. Now you will get an optional warning.
Warnings relating to the use of the new restricted hashes featurehave been added.
Self-ties of arrays and hashes are not supported and fatal errorswill happen even at an attempt to do so.
Using sort in scalar context now issues an optional warning.This didn't do anything useful, as the sort was not performed.
Using the /g modifier in split() is meaningless and will cause a warning.
Using splice() past the end of an array now causes a warning.
Malformed Unicode encodings (UTF-8 and UTF-16) cause a lot of warnings,as does trying to use UTF-16 surrogates (which are unimplemented).
Trying to use Unicode characters on an I/O stream without marking thestream's encoding (using open() or binmode()) will cause "Wide character"warnings.
Use of v-strings in use/require causes a (backward) portability warning.
Warnings relating to the use interpreter threads and their shared datahave been added.

Changed Internals

PerlIO is now the default.
perlapi.pod (a companion to perlguts) now attempts to document theinternal API.
You can now build a really minimal perl called microperl.Building microperl does not require even running Configure;make -f Makefile.micro should be enough. Beware: microperl makesmany assumptions, some of which may be too bold; the resultingexecutable may crash or otherwise misbehave in wondrous ways.For careful hackers only.
Added rsignal(), whichsig(), do_join(), op_clear, op_null,ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8interfaces to the publicised API. For the full list of the availableAPIs see perlapi.
Made possible to propagate customised exceptions via croak()ing.
Now xsubs can have attributes just like subs. (Well, at least thebuilt-in attributes.)
dTHR and djSP have been obsoleted; the former removed (because it'sa no-op) and the latter replaced with dSP.
PERL_OBJECT has been completely removed.
The MAGIC constants (e.g. 'P') have been macrofied(e.g. PERL_MAGIC_TIED) for better source code readabilityand maintainability.
The regex compiler now maintains a structure that identifies nodes inthe compiled bytecode with the corresponding syntactic features of theoriginal regex expression. The information is attached to the newoffsets member of the struct regexp. See perldebguts for morecomplete information.
The C code has been made much more gcc -Wall clean. Some warningmessages still remain in some platforms, so if you are compiling withgcc you may see some warnings about dubious practices. The warningsare being worked on.
perly.c, sv.c, and sv.h have now been extensively commented.
Documentation on how to use the Perl source repository has been addedto Porting/repository.pod.
There are now several profiling make targets.

Security Vulnerability Closed [561]

(This change was already made in 5.7.0 but bears repeating here.)(5.7.0 came out before 5.6.1: the development branch 5.7 releasedearlier than the maintenance branch 5.6)

A potential security vulnerability in the optional suidperl componentof Perl was identified in August 2000. suidperl is neither built norinstalled by default. As of November 2001 the only known vulnerableplatform is Linux, most likely all Linux distributions. CERT andvarious 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.txtfor more information.

The problem was caused by Perl trying to report a suspected securityexploit attempt using an external program, /bin/mail. On Linuxplatforms the /bin/mail program had an undocumented feature whichwhen combined with suidperl gave access to a root shell, resulting ina serious compromise instead of reporting the exploit attempt. If youdon't have /bin/mail, or if you have 'safe setuid scripts', or ifsuidperl is not installed, you are safe.

The exploit attempt reporting feature has been completely removed fromPerl 5.8.0 (and the maintenance release 5.6.1, and it was removed alsofrom all the Perl 5.7 releases), so that particular vulnerabilityisn't there anymore. However, further security vulnerabilities are,unfortunately, always possible. The suidperl functionality is mostprobably going to be removed in Perl 5.10. In any case, suidperlshould only be used by security experts who know exactly what they aredoing and why they are using suidperl instead of some other solutionsuch as sudo ( see http://www.courtesan.com/sudo/ ).

New Tests

Several new tests have been added, especially for the lib andext subsections. There are now about 69 000 individual tests(spread over about 700 test scripts), in the regression suite (5.6.1has about 11 700 tests, in 258 test scripts) The exact numbers dependon the platform and Perl configuration used. Many of the new testsare of course introduced by the new modules, but still in general Perlis now more thoroughly tested.

Because of the large number of tests, running the regression suitewill take considerably longer time than it used to: expect the suiteto take up to 4-5 times longer to run than in perl 5.6. On a reallyfast machine you can hope to finish the suite in about 6-8 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 movedto be closer to the library/extension they are testing.)

Known Problems

The Compiler Suite Is Still Very Experimental

The compiler suite is slowly getting better but it continues to behighly experimental. Use in production environments is discouraged.

Localising Tied Arrays and Hashes Is Broken

 local %tied_array;

doesn't work as one would expect: the old value is restoredincorrectly. This will be changed in a future release, but we don'tknow yet what the new semantics will exactly be. In any case, thechange will break existing code that relies on the current(ill-defined) semantics, so just avoid doing this in general.

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 offsetsdefault to 64 bits wide, where supported. Modules may fail to compileat all, or they may compile and work incorrectly. Currently, thereis no good solution for the problem, but Configure now providesappropriate non-largefile ccflags, ldflags, libswanted, and libsin the %Config hash (e.g., $Config{ccflags_nolargefiles}) so theextensions that are having problems can try configuring themselveswithout the largefileness. This is admittedly not a clean solution,and the solution may not even work at all. One potential failure iswhether one can (or, if one can, whether it's a good idea to) linktogether at all binaries with different ideas about file offsets;all this is platform-dependent.

Modifying $_ Inside for(..)

   for (1..5) { $_++ }

works without complaint. It shouldn't. (You should be able tomodify only lvalue elements inside the loops.) You can see thecorrect behaviour by replacing the 1..5 with 1, 2, 3, 4, 5.

mod_perl 1.26 Doesn't Build With Threaded Perl

Use mod_perl 1.27 or higher.

lib/ftmp-security tests warn 'system possibly insecure'

Don't panic. Read the 'make test' section of INSTALL instead.

libwww-perl (LWP) fails base/date #51

Use libwww-perl 5.65 or later.

PDL failing some tests

Use PDL 2.3.4 or later.

Perl_get_sv

You may get errors like 'Undefined symbol "Perl_get_sv"' or "can'tresolve symbol 'Perl_get_sv'", or the symbol may be "Perl_sv_2pv".This probably means that you are trying to use an older shared Perllibrary (or extensions linked with such) with Perl 5.8.0 executable.Perl used to have such a subroutine, but that is no more the case.Check your shared library path, and any shared Perl libraries in thosedirectories.

Sometimes this problem may also indicate a partial Perl 5.8.0installation, see Mac OS X dyld undefined symbols for anexample and how to deal with it.

Self-tying Problems

Self-tying of arrays and hashes is broken in rather deep andhard-to-fix ways. As a stop-gap measure to avoid people from gettingfrustrated at the mysterious results (core dumps, most often), it isforbidden for now (you will get a fatal error even from an attempt).

A change to self-tying of globs has caused them to be recursivelyreferenced (see: Two-Phased Garbage Collection in perlobj). Youwill now need an explicit untie to destroy a self-tied glob. Thisbehaviour may be fixed at a later date.

Self-tying of scalars and IO thingies works.

ext/threads/t/libc

If this test fails, it indicates that your libc (C library) is notthreadsafe. This particular test stress tests the localtime() call tofind out whether it is threadsafe. See perlthrtut for more information.

Failure of Thread (5.005-style) tests

Note that support for 5.005-style threading is deprecated,experimental and practically unsupported. In 5.10, it is expectedto be removed. You should migrate your code to ithreads.

The following tests are known to fail due to fundamental problems inthe 5.005 threading implementation. These are not new failures--Perl5.005_0x has the same bugs, but didn't have these tests.

 ../ext/B/t/xref.t 255 65280 14   12  85.71%  3-14
  ../ext/List/Util/t/first.t   255 65280 7 4  57.14%  2 5-7
  ../lib/English.t   2   512 54 2   3.70%  2-3
  ../lib/FileCache.t 5 1  20.00%  5
  ../lib/Filter/Simple/t/data.t  6 3  50.00%  1-3
  ../lib/Filter/Simple/t/filter_only. 9 3  33.33%  1-2 5
  ../lib/Math/BigInt/t/bare_mbf.t 1627 4   0.25%  8 11 1626-1627
  ../lib/Math/BigInt/t/bigfltpm.t 1629 4   0.25%  10 13 1628-
  1629
  ../lib/Math/BigInt/t/sub_mbf.t  1633 4   0.24%  8 11 1632-1633
  ../lib/Math/BigInt/t/with_sub.t 1628 4   0.25%  9 12 1627-1628
  ../lib/Tie/File/t/31_autodefer.t 255 65280 65   32  49.23%  34-65
  ../lib/autouse.t  10 1  10.00%  4
  op/flip.t 15 1   6.67%  15

These failures are unlikely to get fixed as 5.005-style threadsare considered fundamentally broken. (Basically what happens is thatcompeting threads can corrupt shared global state, one good examplebeing regular expression engine's state.)

Timing problems

The following tests may fail intermittently because of timingproblems, for example if the system is heavily loaded.

 t/op/alarm.t
  ext/Time/HiRes/HiRes.t
  lib/Benchmark.t
  lib/Memoize/t/expmod_t.t
  lib/Memoize/t/speed.t

In case of failure please try running them manually, for example

 ./perl -Ilib ext/Time/HiRes/HiRes.t

Tied/Magical Array/Hash Elements Do Not Autovivify

For normal arrays $foo = \$bar[1] will assign undef to$bar[1] (assuming that it didn't exist before), but fortied/magical arrays and hashes such autovivification does not happenbecause there is currently no way to catch the reference creation.The same problem affects slicing over non-existent indices/keys ofa tied/magical array/hash.

Unicode in package/class and subroutine names does not work

One can have Unicode in identifier names, but not in package/class orsubroutine names. While some limited functionality towards this doesexist as of Perl 5.8.0, that is more accidental than designed; use ofUnicode for the said purposes is unsupported.

One reason of this unfinishedness is its (currently) inherentunportability: since both package names and subroutine names mayneed to be mapped to file and directory names, the Unicode capabilityof the filesystem becomes important-- and there unfortunately aren'tportable answers.

Platform Specific Problems

AIX

If using the AIX native make command, instead of just "make" issue"make all". In some setups the former has been known to spuriouslyalso try to run "make install". Alternatively, you may want to useGNU make.
In AIX 4.2, Perl extensions that use C++ functions that use staticsmay have problems in that the statics are not getting initialized.In newer AIX releases, this has been solved by linking Perl withthe libC_r library, but unfortunately in AIX 4.2 the said libraryhas an obscure bug where the various functions related to time(such as time() and gettimeofday()) return broken values, andtherefore in AIX 4.2 Perl is not linked against libC_r.
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 a few random tests failing when run as part of "maketest", 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 beenknown to compile Perl correctly. "lslpp -L|grep vac.C" will tellyou the vac version. See README.aix.
If building threaded Perl, you may get compilation warning from pp_sys.c:
```
  "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.
 
```
This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r()having slightly different types for their first argument.

Alpha systems with old gccs fail several tests

If you see op/pack, op/pat, op/regexp, or ext/Storable tests failingin a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc.gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 maybe even better. (RedHat Linux/alpha with gcc 3.1 reported no problems,as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable touse the bundled C compiler.)

AmigaOS

Perl 5.8.0 doesn't build in AmigaOS. It broke at some point duringthe ithreads work and we could not find Amiga experts to unbreak theproblems. Perl 5.6.1 still works for AmigaOS (as does the 5.7.2development release).

BeOS

The following tests fail on 5.8.0 Perl in BeOS Personal 5.03:

 t/op/lfs............................FAILED at test 17
  t/op/magic..........................FAILED at test 24
  ext/Fcntl/t/syslfs..................FAILED at test 17
  ext/File/Glob/t/basic...............FAILED at test 3
  ext/POSIX/t/sigaction...............FAILED at test 13
  ext/POSIX/t/waitpid.................FAILED at test 1

See perlbeos (README.beos) for more details.

Cygwin "unable to remap"

For example when building the Tk extension for Cygwin,you may get an error message saying "unable to remap".This is known problem with Cygwin, and a workaround isdetailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html

Cygwin ndbm tests fail on FAT

One can build but not install (or test the build of) the NDBM_Fileon FAT filesystems. Installation (or build) on NTFS works fine.If one attempts the test on a FAT install (or build) the followingfailures are expected:

 ../ext/NDBM_File/ndbm.t   13  3328 71   59  83.10%  1-2 4 16-71
  ../ext/ODBM_File/odbm.t  255 65280 ??   ??   %  ??
  ../lib/AnyDBM_File.t   2   512 12 2  16.67%  1 4
  ../lib/Memoize/t/errors.t  0   139 11 5  45.45%  7-11
  ../lib/Memoize/t/tie_ndbm.t   13  3328 4 4 100.00%  1-4
  run/fresh_perl.t  97 1   1.03%  91

NDBM_File fails and ODBM_File just coredumps.

If you intend to run only on FAT (or if using AnyDBM_File on FAT),run Configure with the -Ui_ndbm and -Ui_dbm options to preventNDBM_File and ODBM_File being built.

DJGPP Failures

 t/op/stat............................FAILED at test 29
  lib/File/Find/t/find.................FAILED at test 1
  lib/File/Find/t/taint................FAILED at test 1
  lib/h2xs.............................FAILED at test 15
  lib/Pod/t/eol........................FAILED at test 1
  lib/Test/Harness/t/strap-analyze.....FAILED at test 8
  lib/Test/Harness/t/test-harness......FAILED at test 23
  lib/Test/Simple/t/exit...............FAILED at test 1

The above failures are known as of 5.8.0 with native builds with longfilenames, but there are a few more if running under dosemu because oflimitations (and maybe bugs) of dosemu:

 t/comp/cpp...........................FAILED at test 3
  t/op/inccode.........................(crash)

and a few lib/ExtUtils tests, and several hundred Encode/t/Aliases.tfailures that work fine with long filenames. So you really mightprefer native builds and long filenames.

FreeBSD built with ithreads coredumps reading large directories

This is a known bug in FreeBSD 4.5's readdir_r(), it has been fixed inFreeBSD 4.6 (see perlfreebsd (README.freebsd)).

FreeBSD Failing locale Test 117 For ISO 8859-15 Locales

The ISO 8859-15 locales may fail the locale test 117 in FreeBSD.This is caused by the characters \xFF (y with diaeresis) and \xBE(Y with diaeresis) not behaving correctly when being matchedcase-insensitively. Apparently this problem has been fixed inthe latest FreeBSD releases.( http://www.freebsd.org/cgi/query-pr.cgi?pr=34308 )

IRIX fails ext/List/Util/t/shuffle.t or Digest::MD5

IRIX with MIPSpro 7.3.1.2m or 7.3.1.3m compiler may fail the List::Utiltest ext/List/Util/t/shuffle.t by dumping core. This seems to bea compiler error since if compiled with gcc no core dump ensues, andno failures have been seen on the said test on any other platform.

Similarly, building the Digest::MD5 extension has beenknown to fail with "*** Termination code 139 (bu21)".

The cure is to drop optimization level (Configure -Doptimize=-O2).

HP-UX lib/posix Subtest 9 Fails When LP64-Configured

If perl is configured with -Duse64bitall, the successful result of thesubtest 10 of lib/posix may arrive before the successful result of thesubtest 9, which confuses the test harness so much that it thinks thesubtest 9 failed.

Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint

This is a known bug in the glibc 2.2.5 with long long integers.( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )

Linux With Sfio Fails op/misc Test 48

No known fix.

Mac OS X

Please remember to set your environment variable LC_ALL to "C"(setenv LC_ALL C) before running "make test" to avoid a lot ofwarnings about the broken locales of Mac OS X.

The following tests are known to fail in Mac OS X 10.1.5 because ofbuggy (old) implementations of Berkeley DB included in Mac OS X:

 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

If you are building on a UFS partition, you will also probably seet/op/stat.t subtest #9 fail. This is caused by Darwin's UFS notsupporting inode change time.

Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped fornow because the failure is Apple's fault, not Perl's (blocked signalsare lost).

If you Configure with ithreads, ext/threads/t/libc.t will fail. Again,this is not Perl's fault-- the libc of Mac OS X is not threadsafe(in this particular test, the localtime() call is found to bethreadunsafe.)

Mac OS X dyld undefined symbols

If after installing Perl 5.8.0 you are getting warnings about missingsymbols, for example

 dyld: perl Undefined symbols
  _perl_sv_2pv
  _perl_get_sv

you probably have an old pre-Perl-5.8.0 installation (or parts of one)in /Library/Perl (the undefined symbols used to exist in pre-5.8.0 Perls).It seems that for some reason "make install" doesn't always completelyoverwrite the files in /Library/Perl. You can move the old Perlshared library out of the way like this:

 cd /Library/Perl/darwin/CORE
  mv libperl.dylib libperlold.dylib

and then reissue "make install". Note that the above of course isextremely disruptive for anything using the /usr/local/bin/perl.If that doesn't help, you may have to try removing all the .bundlefiles from beneath /Library/Perl, and again "make install"-ing.

OS/2 Test Failures

The following tests are known to fail on OS/2 (for clarityonly the failures are shown, not the full error messages):

 ../lib/ExtUtils/t/Mkbootstrap.t 1   256 18 1   5.56%  8
  ../lib/ExtUtils/t/Packlist.t   1   256 34 1   2.94%  17
  ../lib/ExtUtils/t/basic.t  1   256 17 1   5.88%  14
  lib/os2_process.t  2   512   227 2   0.88%  174 209
  lib/os2_process_kid.t 227 2   0.88%  174 209
  lib/rx_cmprt.t   255 65280 18 3  16.67%  16-18

op/sprintf tests 91, 129, and 130

The op/sprintf tests 91, 129, and 130 are known to fail on some platforms.Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.

Test 91 is known to fail on QNX6 (nto), because sprintf '%e',0incorrectly produces 0.000000e+0 instead of 0.000000e+00.

For tests 129 and 130, the failing platforms do not comply withthe ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, tobe exact. (They produce something other than "1" and "-1" whenformatting 0.6 and -0.6 using the printf format "%.0f"; most often,they produce "0" and "-0".)

SCO

The socketpair tests are known to be unhappy in SCO 3.2v5.0.4:

 ext/Socket/socketpair.t...............FAILED tests 15-45

Solaris 2.5

In case you are still using Solaris 2.5 (aka SunOS 5.5), you mayexperience failures (the test core dumping) in lib/locale.t.The suggested cure is to upgrade your Solaris.

Solaris x86 Fails Tests With -Duse64bitint

The following tests are known to fail in Solaris x86 with Perlconfigured to use 64 bit integers:

 ext/Data/Dumper/t/dumper.............FAILED at test 268
  ext/Devel/Peek/Peek..................FAILED at test 7

SUPER-UX (NEC SX)

The following tests are known to fail on SUPER-UX:

 op/64bitint...........................FAILED tests 29-30, 32-33, 35-36
  op/arith..............................FAILED tests 128-130
  op/pack...............................FAILED tests 25-5625
  op/pow................................
  op/taint..............................# msgsnd failed
  ../ext/IO/lib/IO/t/io_poll............FAILED tests 3-4
  ../ext/IPC/SysV/ipcsysv...............FAILED tests 2, 5-6
  ../ext/IPC/SysV/t/msg.................FAILED tests 2, 4-6
  ../ext/Socket/socketpair..............FAILED tests 12
  ../lib/IPC/SysV.......................FAILED tests 2, 5-6
  ../lib/warnings.......................FAILED tests 115-116, 118-119

The op/pack failure ("Cannot compress negative numbers at op/pack.t line 126")is serious but as of yet unsolved. It points at some problems with thesignedness handling of the C compiler, as do the 64bitint, arith, and powfailures. Most of the rest point at problems with SysV IPC.

Term::ReadKey not working on Win32

Use Term::ReadKey 2.20 or later.

UNICOS/mk

During Configure, the test
```
 Guessing which symbols your C compiler and preprocessor define...
 
```
will probably fail with error messages like
```
 CC-20 cc: ERROR File = try.c, Line = 3
   The identifier "bad" is undefined.
 
   bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
   ^
 
  CC-65 cc: ERROR File = try.c, Line = 3
   A semicolon is expected at this point.
 
```
This is caused by a bug in the awk utility of UNICOS/mk. You can ignorethe error, but it does cause a slight problem: you cannot fullybenefit from the h2ph utility (see h2ph) that can be used toconvert C headers to Perl libraries, mainly used to be able to accessfrom Perl the constants defined using C preprocessor, cpp. Because ofthe above error, parts of the converted headers will be invisible.Luckily, these days the need for h2ph is rare.
If building Perl with interpreter threads (ithreads), thegetgrent(), getgrnam(), and getgrgid() functions cannot return thelist of the group members due to a bug in the multithreaded support ofUNICOS/mk. What this means is that in list context the functions willreturn only three values, not four.

UTS

There are a few known test failures, see perluts (README.uts).

VOS (Stratus)

When Perl is built using the native build process on VOS Release14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests eitherpass or result in TODO (ignored) failures.

VMS

There should be no reported test failures with a default configuration,though there are a number of tests marked TODO that point to areasneeding further debugging and/or porting work.

Win32

In multi-CPU boxes, there are some problems with the I/O buffering:some output may appear twice.

XML::Parser not working

Use XML::Parser 2.31 or later.

z/OS (OS/390)

z/OS has rather many test failures but the situation is actually muchbetter than it was in 5.6.0; it's just that so many new modules andtests have been added.

 Failed Test   Stat Wstat Total Fail  Failed  List of Failed
  ---------------------------------------------------------------------------
  ../ext/Data/Dumper/t/dumper.t  357 8   2.24%  311 314 325 327
   331 333 337 339
  ../ext/IO/lib/IO/t/io_unix.t 5 4  80.00%  2-5
  ../ext/Storable/t/downgrade.t   12  3072   169   12   7.10%  14-15 46-47 78-79
   110-111 150 161
  ../lib/ExtUtils/t/Constant.t   121 30976 48   48 100.00%  1-48
  ../lib/ExtUtils/t/Embed.t 9 9 100.00%  1-9
  op/pat.t   922 7   0.76%  665 776 785 832-
   834 845
  op/sprintf.t   224 3   1.34%  98 100 136
  op/tr.t 97 5   5.15%  63 71-74
  uni/fold.t 780 6   0.77%  61 169 196 661
   710-711

The failures in dumper.t and downgrade.t are problems in the tests,those in io_unix and sprintf are problems in the USS (UDP sockets andprintf formats). The pat, tr, and fold failures are genuine Perlproblems caused by EBCDIC (and in the pat and fold cases, combiningthat with Unicode). The Constant and Embed are probably problems inthe tests (since they test Perl's ability to build extensions, andthat seems to be working reasonably well.)

Unicode Support on EBCDIC Still Spotty

Though mostly working, Unicode support still has problem spots onEBCDIC platforms. One such known spot are the \p{} and \P{}regular expression constructs for code points less than 256: thepP are testing for Unicode code points, not knowing about EBCDIC.

Seen In Perl 5.7 But Gone Now

Time::Piece (previously known as Time::Object) was removedbecause it was felt that it didn't have enough value in it to be acore module. It is still a useful module, though, and is availablefrom the CPAN.

Perl 5.8 unfortunately does not build anymore on AmigaOS; this brokeaccidentally at some point. Since there are not that many Amigadevelopers available, we could not get this fixed and tested in timefor 5.8.0. Perl 5.6.1 still works for AmigaOS (as does the 5.7.2development release).

The PerlIO::Scalar and PerlIO::Via (capitalised) were renamed asPerlIO::scalar and PerlIO::via (all lowercase) just before 5.8.0.The main rationale was to have all core PerlIO layers to have alllowercase names. The "plugins" are named as usual, for examplePerlIO::via::QuotedPrint.

The threads::shared::queue and threads::shared::semaphore wererenamed as Thread::Queue and Thread::Semaphore just before 5.8.0.The main rationale was to have thread modules to obey normal naming,Thread:: (the threads and threads::shared themselves aremore pragma-like, they affect compile-time, so they stay lowercase).

Reporting Bugs

If you find what you think is a bug, you might check the articlesrecently posted to the comp.lang.perl.misc newsgroup and the perlbug database at http://bugs.perl.org/ . There may also beinformation at http://www.perl.com/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbugprogram included with your release. Be sure to trim your bug downto a tiny but sufficient test case. Your bug report, along with theoutput of perl -V, will be sent off to [email protected] to beanalysed by the Perl porting team.

HISTORY

Written by Jarkko Hietaniemi <[email protected]>.

Page index

NAME
DESCRIPTION
Highlights In 5.8.0
Incompatible Changes
- Binary Incompatibility
- 64-bit platforms and malloc
- AIX Dynaloading
- Attributes for my variables now handled at run-time
- Socket Extension Dynamic in VMS
- IEEE-format Floating Point Default on OpenVMS Alpha
- New Unicode Semantics (no more use utf8, almost)
- New Unicode Properties
- REF(...) Instead Of SCALAR(...)
- pack/unpack D/F recycled
- glob() now returns filenames in alphabetical order
- Deprecations
Core Enhancements
- Unicode Overhaul
- PerlIO is Now The Default
- ithreads
- Restricted Hashes
- Safe Signals
- Understanding of Numbers
- Arrays now always interpolate into double-quoted strings [561]
- Miscellaneous Changes
Modules and Pragmata
- New Modules and Pragmata
- Updated And Improved Modules and Pragmata
Utility Changes
New Documentation
Performance Enhancements
Installation and Configuration Improvements
- Generic Improvements
- New Or Improved Platforms
Selected Bug Fixes
- Platform Specific Changes and Fixes
New or Changed Diagnostics
Changed Internals
Security Vulnerability Closed [561]
New Tests
Known Problems
- The Compiler Suite Is Still Very Experimental
- Localising Tied Arrays and Hashes Is Broken
- Building Extensions Can Fail Because Of Largefiles
- Modifying $_ Inside for(..)
- mod_perl 1.26 Doesn't Build With Threaded Perl
- lib/ftmp-security tests warn 'system possibly insecure'
- libwww-perl (LWP) fails base/date #51
- PDL failing some tests
- Perl_get_sv
- Self-tying Problems
- ext/threads/t/libc
- Failure of Thread (5.005-style) tests
- Timing problems
- Tied/Magical Array/Hash Elements Do Not Autovivify
- Unicode in package/class and subroutine names does not work
Platform Specific Problems
- AIX
- Alpha systems with old gccs fail several tests
- AmigaOS
- BeOS
- Cygwin "unable to remap"
- Cygwin ndbm tests fail on FAT
- DJGPP Failures
- FreeBSD built with ithreads coredumps reading large directories
- FreeBSD Failing locale Test 117 For ISO 8859-15 Locales
- IRIX fails ext/List/Util/t/shuffle.t or Digest::MD5
- HP-UX lib/posix Subtest 9 Fails When LP64-Configured
- Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint
- Linux With Sfio Fails op/misc Test 48
- Mac OS X
- Mac OS X dyld undefined symbols
- OS/2 Test Failures
- op/sprintf tests 91, 129, and 130
- SCO
- Solaris 2.5
- Solaris x86 Fails Tests With -Duse64bitint
- SUPER-UX (NEC SX)
- Term::ReadKey not working on Win32
- UNICOS/mk
- UTS
- VOS (Stratus)
- VMS
- Win32
- XML::Parser not working
- z/OS (OS/390)
- Unicode Support on EBCDIC Still Spotty
- Seen In Perl 5.7 But Gone Now
Reporting Bugs
SEE ALSO
HISTORY

Source : perldoc.perl.org - Official documentation for the Perl programming language
Site maintained by Jon Allen (JJ) See the project page for more details
Documentation maintained by the Perl 5 Porters

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What is new for perl v5.8.0

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NAME

DESCRIPTION