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       This document describes differences between the 5.6.0
       release and the 5.8.0 release.

       Many of the bug fixes in 5.8.0 were already seen in the
       5.6.1 maintenance release since the two releases were kept
       closely coordinated (while 5.8.0 was still called

       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

       You can see the list of changes in the 5.6.1 release (both
       from the 5.005_03 release and the 5.6.0 release) by read­
       ing 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

       You have to recompile your XS modules.

       (Pure Perl modules should continue to work.)

       The major reason for the discontinuity is the new IO
       architecture called PerlIO.  PerlIO is the default config­
       uration because without it many new features of Perl 5.8
       cannot be used.  In other words: you just have to recom­
       pile your modules containing XS code, sorry about that.

       In future releases of Perl, non-PerlIO aware XS modules
       may become completely unsupported.  This shouldn't be too
       difficult for module authors, however: PerlIO has been
       models than the Perl malloc.  Some memory-hungry Perl
       applications like the PDL don't work well with Perl's mal­
       loc.  Finally, other applications than Perl (such as
       mod_perl) tend to prefer the system malloc.  Such plat­
       forms 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 native dlopen interface of AIX instead of the old emu­
       lated interface.  This change will probably break backward
       compatibility with compiled modules.  The change was made
       to make Perl more compliant with other applications 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 at run-time.  (Subroutine and "our" variables
       still get attributes applied at compile-time.)  See
       attributes for additional details.  In particular, how­
       ever, this allows variable attributes to be useful for
       "tie" interfaces, which was a deficiency of earlier
       releases.  Note that the new semantics doesn't work with
       the Attribute::Handlers module (as of version 0.76).

       Socket Extension Dynamic in VMS

       The Socket extension is now dynamically loaded instead of
       being statically built in.  This may or may not be a prob­
       lem with ancient TCP/IP stacks of VMS: we do not know
       since we weren't able to test Perl in such configurations.

       IEEE-format Floating Point Default on OpenVMS Alpha

       Perl now uses IEEE format (T_FLOAT) as the default inter­
       nal floating point format on OpenVMS Alpha, potentially
       breaking binary compatibility with external libraries or
       existing data.  G_FLOAT is still available as a configura­
       tion option.  The default on VAX (D_FLOAT) has not

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

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

       This was found to be an inconvenient interface, and in
       Perl 5.8 the Unicode model has completely changed: now the
       "Unicodeness" is bound to the data itself, and for most of
       the time "use utf8" is not needed at all.  The only
       a language or a group of languages, while the blocks are
       more artificial groupings of (mostly) 256 characters based
       on the Unicode numbering.

       In general, scripts are more inclusive, but not univer­
       sally so. For example, while the script "Latin" includes
       all the Latin characters and their various diacritic-
       adorned versions, it does not include the various punctua­
       tion 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" prefix is required to signify a
       Unicode block when a block name conflicts with a script
       name. For example, "\p{Tibetan}" refers to the script,
       while "\p{InTibetan}" refers to the block. When there is
       no name conflict, you can omit the "In" from the block
       name (e.g. "\p{BraillePatterns}"), but to 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)" instead of "SCALAR(0x81485ec)" in order
       to be more consistent with the return value of ref().

       pack/unpack D/F recycled

       The undocumented pack/unpack template letters D/F have
       been recycled for better use: now they stand for long dou­
       ble (if supported by the platform) and NV (Perl internal
       floating point type).  (They used to 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 sorted alphabetically to be csh-compliant (which
       is what happened before in most UNIX platforms).
       (bsd_glob() does still sort platform natively, ASCII or
       EBCDIC, unless GLOB_ALPHASORT is specified.) [561]


       ·   The semantics of bless(REF, REF) were unclear and
           of its usefulness.  The core-dumping functionality
           will remain in future available as an explicit call to
           "CORE::dump()", but in future releases 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 that the 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 \-escape any "\w"

       ·   The *glob{FILEHANDLE} is deprecated, use *glob{IO}

       ·   The "package;" syntax ("package" without an argument)
           has been deprecated.  Its semantics were never that
           clear and its implementation even less so.  If you
           have used that feature to disallow all but fully qual­
           ified variables, "use strict;" instead.

       ·   The unimplemented POSIX regex features [[.cc.]] and
           [[=c=]] are still recognised but now cause fatal
           errors.  The previous behaviour of ignoring them by
           default and warning if requested was unacceptable
           since it, in a way, falsely promised that the features
           could be used.

       ·   In future releases, non-PerlIO aware XS modules may
           become completely unsupported.  Since PerlIO is a
           drop-in replacement for stdio at the source code
           level, this shouldn't be that drastic a change.

       ·   Previous versions of perl and some readings of some
           sections of Camel III implied that the ":raw" "disci­
           pline" was the inverse of ":crlf".  Turning off "clrf­
           ness" is no longer enough to make a stream truly
           binary. So the PerlIO ":raw" layer (or "discipline",
           to use the Camel book's older terminology) is now for­
           mally defined as being equivalent to binmode(FH) -
           which is in turn defined as doing whatever is neces­
           sary to pass each byte as-is without any translation.
           In particular binmode(FH) - and hence ":raw" - will
           now turn off both CRLF 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 weird use of the first array element) is

       ·   After years of trying, suidperl is considered to be
           too complex to ever be considered truly secure.  The
           suidperl functionality is likely to be removed in a
           future release.

       ·   The 5.005 threads model (module "Thread") is depre­
           cated and expected to be removed in Perl 5.10.  Multi­
           threaded code should be migrated to the new ithreads
           model (see threads, threads::shared and perlthrtut).

       ·   The long deprecated uppercase aliases for the string
           comparison operators (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 similar functionality, see pack('U0',
           ...) and pack('C0', ...). [561]

       ·   Earlier Perls treated "sub foo (@bar)" as equivalent
           to "sub foo (@)".  The prototypes are now checked bet­
           ter at compile-time for invalid syntax.  An optional
           warning is generated ("Illegal character in proto­
           type...")  but this may be upgraded to a fatal error
           in a future release.

       ·   The "exec LIST" and "system LIST" operations now pro­
           duce warnings on tainted 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 existing behaviour. 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 in regular expressions should work now,
       Unicode in tr/// should work now, Unicode in I/O should
       work now.  See perluniintro for introduction and perluni­
       code for details.

       ·   The Unicode Character Database coming with Perl has
           been upgraded to Unicode 3.2.0.  For more information,
           see http://www.unicode.org/ .  [561+] (5.6.1 has UCD

       ·   For developers interested in enhancing Perl's Unicode
           capabilities: almost all the UCD files are included

       PerlIO is Now The Default

       ·   IO is now by default done via PerlIO rather than sys­
           tem's "stdio".  PerlIO allows "layers" to be "pushed"
           onto a file handle to alter the handle's behaviour.
           Layers can be specified at open time via 3-arg form of

              open($fh,'>:crlf :utf8', $path) || ...

           or on already opened handles via extended "binmode":


           The built-in layers are: unix (low level read/write),
           stdio (as in previous Perls), perlio (re-implementa­
           tion of stdio buffering in a portable manner), crlf
           (does CRLF <=> "\n" translation as on Win32, but
           available on any platform).  A mmap layer may be
           available if platform supports it (mostly UNIXes).

           Layers to be applied by default may be specified via
           the 'open' pragma.

           See "Installation and Configuration Improvements" for
           the effects of PerlIO on your architecture name.

       ·   If your platform supports fork(), you can use the list
           form of "open" for pipes.  For example:

               open KID_PS, "-|", "ps", "aux" or die $!;

           forks the ps(1) command (without spawning a shell, as
           there are more than three arguments to open()), and
           reads its standard output via the "KID_PS" filehandle.
           See perlipc.

       ·   File handles can be marked as accepting Perl's inter­
           nal encoding of Unicode (UTF-8 or UTF-EBCDIC depending
           on platform) by a pseudo layer ":utf8" :


           Note for EBCDIC users: the pseudo layer ":utf8" is
           erroneously named for you since it's not UTF-8 what
           you will be getting but instead UTF-EBCDIC.  See per­
           lunicode, utf8, and http://www.unicode.org/uni­
           code/reports/tr16/ for more information.  In future
           releases this naming may change.  See perluniintro for
           any old eight-bit data is not legal UTF-8.

           Note for code authors: if you want to enable your
           users to use UTF-8 as 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" in perlfunc and
           "binmode" in perlfunc), or you can just use "bin­
           mode(FH)" (nice for pre-5.8.0 backward compatibility).

       ·   File handles can translate character encodings from/to
           Perl's internal Unicode 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.


       The new interpreter threads ("ithreads" for short) imple­
       mentation of multithreading, by Arthur Bergman, replaces
       the old "5.005 threads" implementation.  In the ithreads
       model any data sharing between threads must be explicit,
       as opposed to the model where data sharing was implicit.
       See threads and threads::shared, and perlthrtut.

       As a part of the ithreads implementation Perl will also
       use any necessary and detectable reentrant libc inter­

       Restricted Hashes

       A restricted hash is restricted to a certain set of keys,
       no keys outside the set can be added.  Also individual
       keys can be restricted so 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 inop­
       portune moments could corrupt Perl's internal state.  Now
       Perl postpones handling of signals until it's safe

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

       Perl now tries internally to use integer values in numeric
       conversions and basic arithmetics (+ - * /) if the argu­
       ments are integers, and tries also to keep the results
       stored internally as integers.  This change leads to often
       slightly faster and always less lossy arithmetics. (Previ­
       ously Perl always preferred floating point numbers in its

       Arrays now always interpolate into double-quoted strings

       In double-quoted strings, arrays now interpolate, no mat­
       ter what.  The behavior in earlier versions of perl 5 was
       that arrays would interpolate into strings if the array
       had been mentioned before the string was compiled, 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 as they have always written "Give me back my \$5"
       when they wanted a literal "$" sign.

       Starting with 5.6.1, when Perl now sees an "@" sign in a
       double-quoted string, it always attempts to interpolate an
       array, regardless of whether or not the array has been
       used or declared already.  The fatal error has been down­
       graded to an optional warning:

               Possible unintended interpolation of @example in string

       This warns you that "fred@example.com" is going to turn
       into "fred.com" if you don't backslash the "@".  See
       http://www.plover.com/~mjd/perl/at-error.html for more
       details about the history here.

       Miscellaneous Changes

           cally--this is more robust with "fat binaries" where
           an executable image contains binaries for more than
           one binary platform, and when cross-compiling.

       ·   "perl -d:Module=arg,arg,arg" now works (previously one
           couldn't pass in multiple arguments.)

       ·   "do" followed by a bareword now ensures that this
           bareword isn't a keyword (to avoid a bug where "do
           q(foo.pl)" tried to call a subroutine called "q").
           This means that for example instead of "do format()"
           you must write "do &format()".

       ·   The builtin dump() now gives an optional warning
           "dump() better written as CORE::dump()", meaning that
           by default "dump(...)" is resolved as the builtin
           dump() which dumps core and aborts, not as (possibly)
           user-defined "sub dump".  To call the latter, qualify
           the call as "&dump(...)".  (The whole dump() feature
           is to considered deprecated, and possibly
           removed/changed in future releases.)

       ·   chomp() and chop() are now overridable.  Note, how­
           ever, that their prototype (as given by "proto­
           type("CORE::chomp")" is undefined, because it cannot
           be expressed and therefore one cannot really write
           replacements 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 by PL_exit_flags & PERL_EXIT_DESTRUCT_END.
           This enables the new behaviour for Perl embedders.
           This will default in 5.10. See perlembed.

       ·   Formats now support zero-padded decimal fields.

       ·   Although "you shouldn't do that", it was possible to
           write code that depends on Perl's hashed key order
           (Data::Dumper does this).  The new algorithm
           "One-at-a-Time" produces a different hashed key order.
           More details are in "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 situa­
           tions, when glob() caused File::Glob to be loaded for
           the first time, have been fixed. [561]

       ·   Lvalue subroutines can now return "undef" in list con­
           text.  However, the lvalue subroutine feature still

       ·   The numerical comparison operators return "undef" if
           either operand is a NaN.  Previously the behaviour was

       ·   "our" can now have an experimental optional attribute
           "unique" that affects how global variables are shared
           among multiple interpreters, see "our" in perlfunc.

       ·   The following builtin functions are now overridable:
           each(), keys(), pop(), push(), shift(), splice(),
           unshift(). [561]

       ·   "pack() / unpack()" can now group template letters
           with "()" and then apply 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 sec­
           onds (as the POSIX standard says), as opposed to
           CORE::sleep() which returns the number of slept sec­

       ·   printf() and sprintf() now support parameter reorder­
           ing using the "%\d+\$" and "*\d+\$" syntaxes.  For

               printf "%2\$s %1\$s\n", "foo", "bar";

           will print "bar foo\n".  This feature helps in writing
           internationalised software, and in general when the
           order of the parameters can vary.

       ·   The (\&) prototype now works properly. [561]

       ·   prototype(\[$@%&]) is now available to implicitly cre­
           ate references (useful for example if you want to emu­
           late the tie() interface).

       ·   A new command-line option, "-t" is available.  It is
           the little brother of "-T": instead of dying on taint
           violations, lexical warnings are given.  This is only
           meant as a temporary debugging aid while securing the
           code of old legacy applications.  This is not a sub­

       ·   If tr/// is just counting characters, it doesn't
           attempt to modify its target.

       ·   untie() will now call an UNTIE() hook if it exists.
           See perltie for details. [561]

       ·   utime now supports "utime undef, undef, @files" to
           change the file timestamps to the current time.

       ·   The rules for allowing underscores (underbars) in
           numeric constants have been relaxed and simplified:
           now you can have an underscore simply between digits.

       ·   Rather than relying on C's argv[0] (which may not con­
           tain 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

       ·   A new variable, "${^TAINT}", indicates whether taint
           mode is enabled.

       ·   You can now override the readline() builtin, and this
           overrides also the <FILEHANDLE> angle bracket opera­

       ·   The command-line options -s and -F are now recognized
           on the shebang (#!) line.

       ·   Use of the "/c" match modifier without an accompanying
           "/g" modifier elicits a new warning: "Use of /c modi­
           fier is meaningless without /g".

           Use of "/c" in substitutions, even with "/g", elicits
           "Use of /c modifier is meaningless in s///".

           Use of "/g" with "split" elicits "Use of /g modifier
           is meaningless in 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" you can do what­
           ever you need to do, like for example handle the
           cloning of non-Perl data, if necessary.  "CLONE" will
           be executed once for every package that has it defined
           or inherited.  It will be called in the context of the
           new thread, so all modifications are made in the new

           See perlmod

               my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called

           Both variables and routines can have attribute han­
           dlers.  Handlers can be specific to type (SCALAR,
           ARRAY, HASH, or CODE), or specific to the exact compi­
           lation phase (BEGIN, CHECK, INIT, or END).  See

       ·   "B::Concise", by Stephen McCamant, is a new compiler
           backend for walking the Perl syntax tree, printing
           concise info about ops.  The output is highly cus­
           tomisable.  See B::Concise. [561+]

       ·   The new bignum, bigint, and bigrat pragmas, by Tels,
           implement transparent bignum support (using the
           Math::BigInt, Math::BigFloat, and Math::BigRat back­

       ·   "Class::ISA", by Sean Burke, is a module for reporting
           the search path for a class's ISA tree.  See

       ·   "Cwd" now has a split personality: if possible, an XS
           extension is used, (this will hopefully be faster,
           more secure, and more robust) but if not possible, the
           familiar Perl implementation is used.

       ·   "Devel::PPPort", originally by Kenneth Albanowski and
           now maintained by Paul Marquess, has been added.  It
           is primarily used by "h2xs" to enhance portability of
           XS modules between different versions of Perl.  See

       ·   "Digest", frontend module for calculating digests
           (checksums), from Gisle Aas, has been added.  See

       ·   "Digest::MD5" for calculating MD5 digests (checksums)
           as defined in RFC 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 not included since its further use is

           See also PerlIO::via::QuotedPrint.
           Any encoding supported by Encode module is also avail­
           able to the ":encoding()" layer if PerlIO is used.

       ·   "Hash::Util" is the interface to the new restricted
           hashes feature.  (Implemented by Jeffrey Friedl, Nick
           Ing-Simmons, and Michael Schwern.)  See Hash::Util.

       ·   "I18N::Langinfo" can be used to query locale informa­
           tion.  See I18N::Langinfo.

       ·   "I18N::LangTags", by Sean Burke, has functions for
           dealing with RFC3066-style language tags.  See

       ·   "ExtUtils::Constant", by Nicholas Clark, is a new tool
           for extension writers for generating XS code to import
           C header constants.  See ExtUtils::Constant.

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

               # in MyFilter.pm:

               package MyFilter;

               use Filter::Simple sub {
                   while (my ($from, $to) = splice @_, 0, 2) {


               # 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 files and directories in an easy, portable,
           and secure way.  See File::Temp.  [561+]

       ·   "Filter::Util::Call", by Paul Marquess, provides you
           with the framework to write source filters in Perl.
           For most uses, the frontend Filter::Simple is to be
           preferred.  See Filter::Util::Call.
           first(), and shuffle().  See List::Util.

       ·   "Locale::Constants", "Locale::Country", "Locale::Cur­
           rency" "Locale::Language", and Locale::Script, by Neil
           Bowers, have been added.  They provide the codes for
           various locale standards, such as "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::Cur­
           rency, and Locale::Language.

       ·   "Locale::Maketext", by Sean Burke, is a localization
           framework.  See Locale::Maketext, and Locale::Make­
           text::TPJ13.  The latter is an article about software
           localization, originally published in The Perl Journal
           #13, and republished here with kind permission.

       ·   "Math::BigRat" for big rational numbers, to accompany
           Math::BigInt and Math::BigFloat, from Tels.  See

       ·   "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 (Multi­
           purpose Internet Mail Extensions).

               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 data in quoted-printable encoding, as defined
           in RFC 2045 - MIME (Multipurpose Internet Mail Exten­

               use MIME::QuotedPrint;

               $encoded = encode_qp("\xDE\xAD\xBE\xEF");
               $decoded = decode_qp($encoded);

           loadable PerlIO layer.  Other future possibilities
           include PerlIO::Array and PerlIO::Code.  See Per­

       ·   "PerlIO::via", by Nick Ing-Simmons, acts as a PerlIO
           layer and wraps PerlIO layer functionality provided by
           a class (typically implemented in Perl code).

       ·   "PerlIO::via::QuotedPrint", by Elizabeth Mattijsen, is
           an example of a "PerlIO::via" class:

               use PerlIO::via::QuotedPrint;

           This will automatically convert everything output to
           $fh to Quoted-Printable.  See PerlIO::via and Per­

       ·   "Pod::ParseLink", by Russ Allbery, has been added, to
           parse L<> links in pods as described in the new

       ·   "Pod::Text::Overstrike", by Joe Smith, has been added.
           It converts POD data to formatted overstrike text.
           See Pod::Text::Overstrike. [561+]

       ·   "Scalar::Util" is a selection of general-utility
           scalar subroutines, such as blessed(), reftype(), and
           tainted().  See Scalar::Util.

       ·   "sort" is a new pragma for controlling the behaviour
           of sort().

       ·   "Storable" gives persistence to Perl data structures
           by allowing the storage and retrieval of Perl data to
           and from files in a fast and compact binary format.
           Because in effect Storable does serialisation of Perl
           data structures, with it you can also clone deep,
           hierarchical datastructures.  Storable was originally
           created by Raphael Manfredi, but it is now maintained
           by Abhijit Menon-Sen.  Storable has been enhanced to
           understand the two new hash features, Unicode keys and
           restricted hashes.  See Storable.

       ·   "Switch", by Damian Conway, has been added.  Just by

               use Switch;

           you have "switch" and "case" available in Perl.

               use Switch;
                           case (\%hash)   { print "entry in hash" }
                           case (\&sub)    { print "arg to subroutine" }
                           else            { print "previous case not true" }

           See Switch.

       ·   "Test::More", by Michael Schwern, is yet another
           framework for writing test scripts, more extensive
           than Test::Simple.  See Test::More.

       ·   "Test::Simple", by Michael Schwern, has basic utili­
           ties for writing tests.   See Test::Simple.

       ·   "Text::Balanced", by Damian Conway, has been added,
           for extracting delimited text sequences from strings.

               use Text::Balanced 'extract_delimited';

               ($a, $b) = extract_delimited("'never say never', he never said", "'", '');

           $a will be "'never say never'", $b will be ', he never

           In addition to extract_delimited(), there are also
           extract_bracketed(), extract_quotelike(),
           extract_codeblock(), extract_variable(),
           extract_tagged(), extract_multiple(), gen_delim­
           ited_pat(), and gen_extract_tagged().  With these, you
           can implement rather advanced parsing algorithms.  See

       ·   "threads", by Arthur Bergman, is an interface to
           interpreter threads.  Interpreter threads (ithreads)
           is the new thread model introduced in Perl 5.6 but
           only available as an internal interface for extension
           writers (and for Win32 Perl for "fork()" emulation).
           See threads, threads::shared, and perlthrtut.

       ·   "threads::shared", by Arthur Bergman, allows data
           sharing for interpreter threads.  See threads::shared.

       ·   "Tie::File", by Mark-Jason Dominus, associates a Perl
           array with the lines of a file.  See Tie::File.

       ·   "Tie::Memoize", by Ilya Zakharevich, provides on-
           demand loaded hashes.  See Tie::Memoize.

       ·   "Tie::RefHash::Nestable", by Edward Avis, allows stor­
           ing hash references (unlike the standard Tie::RefHash)
           The module is contained within Tie::RefHash.  See

       ·   "XS::APItest", by Tim Jenness, is a test extension
           that exercises XS APIs.  Currently only "printf()" is
           tested: how to output various basic data types from

       ·   "XS::Typemap", by Tim Jenness, is a test extension
           that exercises XS typemaps.  Nothing gets installed,
           but the code is worth studying for extension writers.

       Updated And Improved Modules and Pragmata

       ·   The following independently supported modules have
           been updated to the newest versions from CPAN: CGI,
           CPAN, DB_File, File::Spec, File::Temp, Getopt::Long,
           Math::BigFloat, Math::BigInt, the podlators bundle
           (Pod::Man, Pod::Text), Pod::LaTeX [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 can now deparse almost all of the stan­
           dard test suite (so that the tests still succeed).
           There is a make target "test.deparse" for trying this

       ·   Carp now has better interface documentation, and the
           @CARP_NOT interface has been added to get optional
           control over where errors are reported independently
           of @ISA, by Ben Tilly.

       ·   Class::Struct can now define the classes in compile

       ·   Class::Struct now assigns the array/hash element if
           the accessor is 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 references
           using B::Deparse.

       ·   DB_File now supports newer Berkeley DB versions, among
           other improvements.

       ·   ExtUtils::MakeMaker has been significantly cleaned up
           and fixed.  The enhanced version has also been back­
           ported to earlier releases of Perl and submitted to
           CPAN so that the earlier releases can enjoy the fixes.

       ·   The arguments of WriteMakefile() in Makefile.PL are
           now checked for sanity much more carefully than
           before.  This may cause new warnings when modules are
           being installed.  See ExtUtils::MakeMaker for more

       ·   ExtUtils::MakeMaker now uses File::Spec internally,
           which hopefully leads to better portability.

       ·   Fcntl, Socket, and Sys::Syslog have been rewritten by
           Nicholas Clark to 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 sym­
           bolic links. [561]

       ·   File::Find now has pre- and post-processing callbacks.
           It also correctly changes directories when chasing
           symbolic links.  Callbacks (naughtily) exiting with
           "next;" instead of "return;" now work.

       ·   File::Find is now (again) reentrant.  It also has been
           made more 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 older name is still available
           for compatibility, but is deprecated. [561]

       ·   File::Glob now supports "GLOB_LIMIT" constant to limit
           the size of the returned list of filenames.

       ·   IPC::Open3 now allows the use of numeric file descrip­

       ·   IO::Socket now has an atmark() method, which returns
           true if the socket is positioned at the out-of-band
           mark.  The method is also exportable as a sockatmark()

       ·   IO::Socket::INET failed to open the specified port if

       ·   Math::BigFloat and Math::BigInt have undergone a full
           rewrite by Tels.  They are now magnitudes faster, and
           they support various bignum libraries 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 is now supported, Win32 functionality is
           better, there is now time measuring functionality
           (optionally high-resolution using Time::HiRes), and
           there is now "external" protocol which uses
           Net::Ping::External module which runs your external
           ping utility and parses the output.  A version of
           Net::Ping::External is available in CPAN.

           Note that some of the Net::Ping tests are disabled
           when running under the Perl distribution since one
           cannot assume one or more of the following: enabled
           echo port at localhost, full Internet connectivity, or
           sympathetic firewalls.  You can set the environment
           variable PERL_TEST_Net_Ping to "1" (one) before run­
           ning the Perl test suite to enable all the Net::Ping

       ·   POSIX::sigaction() is now much more flexible and
           robust.  You can now install coderef handlers,
           'DEFAULT', and 'IGNORE' handlers, installing new han­
           dlers was not atomic.

       ·   In Safe, %INC is now localised in a Safe compartment
           so that use/require work.

       ·   In SDBM_File on dosish platforms, some keys went miss­
           ing because of lack of support for files with "holes".
           A workaround for the problem has been added.

       ·   In Search::Dict one can now have a pre-processing hook
           for the lines being searched.

       ·   The Shell module now has an OO interface.

       ·   In Sys::Syslog there is now a failover mechanism that
           will go through alternative connection mechanisms
           until the message is 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() and localtime() are sup­

       ·   emacs/e2ctags.pl is now much faster.

       ·   "enc2xs" is a tool for people adding their own encod­
           ings to the Encode module.

       ·   "h2ph" now supports C trigraphs.

       ·   "h2xs" now produces a template README.

       ·   "h2xs" now uses "Devel::PPPort" for better portability
           between different versions of Perl.

       ·   "h2xs" uses the new ExtUtils::Constant module which
           will affect newly created extensions that define con­
           stants.  Since the new code is more correct (if you
           have two constants where the first one is a prefix of
           the second one, the first constant never got defined),
           less lossy (it uses integers for integer constant, as
           opposed to the old code that used floating point num­
           bers even for integer constants), and slightly faster,
           you might want to consider regenerating your extension
           code (the new scheme makes regenerating easy).  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 to perl.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 and unsupported.

       ·   "perlivp" is a new Installation Verification Procedure
           utility for running any time after installing Perl.

       ·   "piconv" is an implementation of the character conver­
           sion utility "iconv", demonstrating the new Encode

       ·   "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).

       ·   perlclib documents the internal replacements for stan­
           dard C library functions.  (Interesting only for
           extension writers and Perl core hackers.) [561+]

       ·   perldebtut is a Perl debugging tutorial. [561+]

       ·   perlebcdic contains considerations for running Perl on
           EBCDIC platforms. [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 best practices gathered over the years.

       ·   perlpodspec is a more formal specification of the pod
           format, mainly of interest for writers of pod applica­
           tions, not to people 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 con­
           flict with perltoot in filesystems restricted to "8.3"

       ·   perluniintro is an introduction to using Unicode in
           Perl.  (perlunicode is more of a detailed reference
           and background information)

       ·   perlutil explains the command line utilities packaged
           with the Perl distribution. [561+]

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

           perlaix perlamiga perlapollo perlbeos perlbs2000
           perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux
           perlhurd perlirix perlmachten perlmacos perlmint perlmpeix

          perljp perlko perlcn perltw

       ·   The documentation for the POSIX-BC platform is called
           "BS2000", to avoid confusion with the Perl POSIX mod­

       ·   The documentation for the WinCE platform is called
           perlce (README.ce in the source code kit), to avoid
           confusion with the perlwin32 documentation on
           8.3-restricted filesystems.

Performance Enhancements

       ·   map() could get pathologically slow when the result
           list it generates is larger than the source list.  The
           performance has been improved for common scenarios.

       ·   sort() is also fully reentrant, in the sense that the
           sort function can itself call sort().  This did not
           work reliably in previous releases. [561]

       ·   sort() has been changed to use primarily mergesort
           internally as opposed to the earlier quicksort.  For
           very small lists this may result in slightly slower
           sorting times, but in general the speedup should be at
           least 20%.  Additional bonuses are that the worst case
           behaviour of sort() is now better (in computer science
           terms it now runs in time O(N log N), as opposed to
           quicksort's Theta(N**2) worst-case run time
           behaviour), and that sort() is now stable (meaning
           that elements with identical keys will stay ordered as
           they were before the sort).  See the "sort" pragma for

           The story in more detail: suppose you want to serve
           yourself a little slice of Pi.

               @digits = ( 3,1,4,1,5,9 );

           A numerical sort of the digits will yield
           (1,1,3,4,5,9), as expected.  Which 1 comes first is
           hard to know, since one 1 looks pretty much like any
           other.  You can regard this as totally trivial, or
           somewhat profound.  However, if you just want to sort
           the even digits ahead of the odd ones, then what will

               sort { ($a % 2) <=> ($b % 2) } @digits;

           yield?  The only even digit, 4, will come first.  But
           how about the odd numbers, which all compare equal?
           With the quicksort algorithm used to implement Perl
           5.6 and earlier, the order of ties is left up to the
           like N**2, so-called quadratic behaviour, and it can
           happen on patterns that may well arise in normal use.
           You won't notice this for small arrays, but you will
           notice it with larger arrays, and you may not live
           long enough for the sort to complete on arrays of a
           million elements.  So the 5.8 quicksort scrambles
           large arrays before sorting them, as a statistical
           defence against quadratic behaviour.  But that means
           if you sort the same large array twice, ties may be
           broken in different ways.

           Because of the unpredictability of tie-breaking order,
           and the quadratic worst-case behaviour, quicksort was
           almost replaced completely with a stable mergesort.
           Stable means that ties are broken to preserve the
           original order of appearance in the input array.  So

               sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);

           will yield (4,3,1,1,5,9), guaranteed.  The even and
           odd numbers appear in the output in the same order
           they appeared in the input.  Mergesort has worst case
           O(N log N) behaviour, the best value attainable.  And,
           ironically, this mergesort does particularly well
           where quicksort goes quadratic:  mergesort sorts
           (1..$N, 1..$N) in O(N) time.  But quicksort was res­
           cued at the last moment because it is faster than
           mergesort on certain inputs and platforms.  For exam­
           ple, if you really don't care about the order of even
           and odd digits, quicksort will run in O(N) time; it's
           very good at sorting many repetitions of a small num­
           ber of distinct elements.  The quicksort divide and
           conquer strategy works well on platforms with rela­
           tively small, very fast, caches.  Eventually, the
           problem gets whittled down to one that fits in the
           cache, from which point it benefits from the increased
           memory speed.

           Quicksort was rescued by implementing a sort pragma to
           control aspects of the sort.  The stable subpragma
           forces stable behaviour, regardless of algorithm.  The
           _quicksort and _mergesort subpragmas are heavy-handed
           ways to select the underlying implementation.  The
           leading "_" is a reminder that these subpragmas may
           not survive beyond 5.8.  More appropriate mechanisms
           for selecting the implementation exist, but they
           wouldn't have arrived in time to save quicksort.

       ·   Hashes now use Bob Jenkins "One-at-a-Time" hashing key
           algorithm ( http://burtlebur­
           tle.net/bob/hash/doobs.html ).  This algorithm is rea­
           sonably fast while producing a much better spread of

       ·   INSTALL now explains how you can configure Perl to use
           64-bit integers even on non-64-bit platforms.

       ·   Policy.sh policy change: if you are reusing a Pol­
           icy.sh file (see INSTALL) and you use Configure -Dpre­
           fix=/foo/bar and in the old Policy $prefix eq
           $siteprefix and $prefix eq $vendorprefix, all of them
           will now be changed to the new prefix, /foo/bar.
           (Previously only $prefix changed.)  If you do not like
           this new behaviour, specify prefix, siteprefix, and
           vendorprefix explicitly.

       ·   A new optional location for Perl libraries, otherlib­
           dirs, is available.  It can be used for example for
           vendor add-ons without disturbing Perl's own library

       ·   In many platforms, the vendor-supplied 'cc' is too
           stripped-down to build Perl (basically, 'cc' doesn't
           do ANSI C).  If this seems to be the case and 'cc'
           does not seem to be the GNU C compiler 'gcc', an auto­
           matic attempt is made to find and use 'gcc' instead.

       ·   gcc needs to closely track the operating system
           release to avoid build problems. If Configure finds
           that gcc was built for a different operating system
           release than is running, it now gives a clearly visi­
           ble warning that there may be trouble ahead.

       ·   Since Perl 5.8 is not binary-compatible with previous
           releases of Perl, Configure no longer suggests includ­
           ing the 5.005 modules in @INC.

       ·   Configure "-S" can now run non-interactively. [561]

       ·   Configure support for pdp11-style memory models has
           been removed due to 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't get appended to the $Config{arch­
           name} (also known as $^O) anymore.  Instead, if you
           explicitly choose not to use perlio (Configure command
           line option -Uuseperlio), you will get "-stdio"

       ·   Another change related to the architecture name is
           that "-64all" (-Duse64bitall, or "maximally 64-bit")
           presumably, the DB_File extension) was built is now
           available as @Config{qw(db_version_major db_ver­
           sion_minor db_version_patch)} from Perl and as
           SION_PATCH_CFG" from C.

       ·   Building Berkeley DB3 for compatibility modes for DB,
           NDBM, and ODBM has been documented in INSTALL.

       ·   If you have CPAN access (either network or a local
           copy such as a CD-ROM) you can during specify extra
           modules to Configure to build and install with Perl
           using the -Dextras=...  option.  See INSTALL for more

       ·   In addition to config.over, a new override file, con­
           fig.arch, is available.  This file is supposed to be
           used by hints file writers for architecture-wide
           changes (as opposed to config.over which is for site-
           wide changes).

       ·   If your file system supports symbolic links, you can
           build Perl outside of the source directory by

                   mkdir /tmp/perl/build/directory
                   cd /tmp/perl/build/directory
                   sh /path/to/perl/source/Configure -Dmksymlinks ...

           This will create in /tmp/perl/build/directory a tree
           of symbolic links pointing to files in
           /path/to/perl/source.  The original files are left
           unaffected.  After Configure has finished, you can
           just say

                   make all test

           and Perl will be built and tested, all in
           /tmp/perl/build/directory.  [561]

       ·   For Perl developers, several new make targets for pro­
           filing and debugging have been added; see perlhack.

           ·       Use of the gprof tool to profile Perl has been
                   documented in perlhack.  There is a make tar­
                   get called "perl.gprof" for generating a gpro­
                   filed Perl executable.

           ·       If you have GCC 3, there is a make target
                   called "perl.gcov" for creating a gcoved Perl
                   executable for coverage analysis.  See perl­

           cated: if you have code written for the old threads
           you should migrate it to the new ithreads model.

       ·   The Gconvert macro ($Config{d_Gconvert}) used by perl
           for stringifying floating-point numbers is now more
           picky about using sprintf %.*g rules for the conver­
           sion.  Some platforms that used to use gcvt may now
           resort to the slower sprintf.

       ·   The obsolete method of making a special (e.g., debug­
           ging) flavor of 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 "Sup­
       ported Platforms" in perlport.

       ·   AIX dynamic loading should be now better supported.

       ·   AIX should now work better with gcc, threads, and
           64-bitness.  Also the long 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 or near 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 the co-existence of Unicode
           and EBCDIC isn't quite settled, but the situation is
           much better than with Perl 5.6.  See perlos390,
           perlbs2000 (for POSIX-BC), and perlvmesa for more

       ·   Building perl with -Duseithreads or -Duse5005threads
           now works under HP-UX 10.20 (previously it only worked
           under 10.30 or later). You will need a thread library
           package installed. See README.hpux. [561]

       ·   Mac OS Classic is now supported in the mainstream
           source package (MacPerl has of course been available

       ·   NetWare from Novell is now supported.  See perlnet­

       ·   NonStop-UX is now supported. [561]

       ·   NEC SUPER-UX is now supported.

       ·   All the OpenBSD specific patches (except for the
           installation specific 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 tests of Perl now work, but not without
           adding some yield()s to the tests, so while pth (and
           other userlevel thread implementations) can be consid­
           ered to be "working" with Perl ithreads, keep in mind
           the possible 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 on VOS.  The older methods, which build
           miniperl, are still available.  See perlvos. [561+]

       ·   The Amdahl UTS UNIX mainframe platform is now sup­
           ported. [561]

       ·   WinCE is now supported.  See perlce.

       ·   z/OS (formerly known as OS/390, formerly known as MVS
           OE) now has support 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 been hunted down.  Most importantly, anonymous subs
       used to leak quite a bit. [561]

       ·   The autouse pragma didn't work for Multi::Part::Func­

       ·   caller() could cause core dumps in certain situations.
           Carp was sometimes affected by this problem.  In par­
           ticular, caller() now returns a subroutine name of
           "(unknown)" for subroutines that have been removed
           from the symbol table.

       ·   chop(@list) in list context returned the characters
           chopped in reverse order.  This has been reversed to
           be in the right order. [561]

       ·   Several debugger fixes: exit code now reflects the
           script exit code, condition "0" now treated correctly,
           the "d" command now checks line number, $. no longer
           gets corrupted, and all debugger output now goes cor­
           rectly to the socket if RemotePort is set. [561]

       ·   The debugger (perl5db.pl) has been modified to present
           a more consistent commands interface, via (Command­
           Set=580).  perl5db.t was also added to test the
           changes, and as a placeholder for further tests.

           See perldebug.

       ·   The debugger has a new "dumpDepth" option to control
           the maximum depth to which nested structures are
           dumped.  The "x" command has been extended so that "x
           N EXPR" dumps out the value of EXPR to a depth of at
           most N levels.

       ·   The debugger can now show lexical variables if you
           have the CPAN module PadWalker installed.

       ·   The order of DESTROYs has been made more predictable.

       ·   Perl 5.6.0 could emit spurious warnings about redefi­
           nition of dl_error() when statically building exten­
           sions 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 broke the Tk extension with 5.6.0.) [561]

       ·   Lexicals I: lexicals outside an eval "" weren't
           resolved correctly inside a subroutine definition
           inside the eval "" if they were not already referenced
           in the top level of the eval""ed code.

       ·   Lexicals II: lexicals leaked at file scope into sub­
           routines that were declared before the lexicals.

       ·   Lexical warnings now propagating correctly between
           scopes and into "eval "..."".

       ·   "use warnings qw(FATAL all)" did not work as intended.
           This has been corrected. [561]


               # 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 unlo­
           calised to not exist, if they didn't before they were

               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 define the 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 builds with "-Duselongdouble".  This version
           of Perl detects this brokenness and has a workaround
           for it.  The glibc release 2.2.2 is known to have
           fixed the modfl() bug.

       ·   Modulus of unsigned numbers now works (4063328477 %
           65535 used to return 27406, instead of 27047). [561]

       ·   Some "not a number" warnings introduced in 5.6.0 elim­
           inated to be more compatible with 5.005.  Infinity is
           now recognised as a number. [561]

       ·   Numeric conversions did not recognize changes in the
           string value properly 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 sib­
           ling blocks resulted in bogus warnings about "redecla­
           ration" of the variables.  The problem has been cor­

       ·   printf() no longer resets the numeric locale to "C".

       ·   "qw(a\\b)" now parses correctly as 'a\\b': that is, as
           three characters, not four. [561]

       ·   pos() did not return the correct value within s///ge
           in earlier versions.  This is now handled correctly.

       ·   Printing quads (64-bit integers) with printf/sprintf
           now works without 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 string concatenation be invoked too many

       ·   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 wantar­
           ray context (they were accidentally using the context
           of the sort() itself).  The comparison block is now
           run in scalar context, and the arguments to be sorted
           are always provided list context. [561]

       ·   Changed the POSIX character class "[[:space:]]" to
           include the (very rarely used) vertical tab character.
           Added a new POSIX-ish character class "[[:blank:]]"
           which stands for horizontal whitespace (currently, the
           space and the tab).

       ·   The tainting behaviour of sprintf() has been rational­
           ized.  It does not taint the result of floating point
           formats anymore, making the behaviour consistent with
           that of string interpolation. [561]

       ·   Some cases of inconsistent taint propagation (such as
           within hash values) have been fixed.

       ·   The RE engine found in Perl 5.6.0 accidentally pes­
           simised certain kinds of 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]
           situations.  This has been corrected. [561]

       ·   Autovivification of symbolic references of special
           variables described in perlvar (as in "${$num}") was
           accidentally disabled.  This works again now. [561]

       ·   Sys::Syslog ignored the "LOG_AUTH" constant.

       ·   $AUTOLOAD, sort(), lock(), and spawning subprocesses
           in multiple threads simultaneously are now

       ·   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" now correctly 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 cor­

           ·       The character tables have been updated to Uni­
                   code 3.2.0.

           ·       Comparing with utf8 data does not magically
                   upgrade non-utf8 data into utf8.  (This was a
                   problem for example if you were mixing data
                   from I/O and Unicode data: your output might
                   have got magically encoded as UTF-8.)

           ·       Generating illegal Unicode code points such as
                   U+FFFE, or the UTF-16 surrogates, now also
                   generates an optional warning.

           ·       "IsAlnum", "IsAlpha", and "IsWord" now match

           ·       Concatenation with the "." operator or via
                   variable interpolation, "eq", "substr",
                   "reverse", "quotemeta", the "x" operator, sub­
                   stitution with "s///", single-quoted UTF-8,
                   should now work.

           ·       The "tr///" operator now works.  Note that the
                   "tr///CU" functionality has been removed (but

       ·   The Perl parser has been stress tested using both ran­
           dom input and Markov chain input and the few found
           crashes and lockups have been fixed.

       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

       ·   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; acci­
           dental mixing of 32-bit and 64-bit libraries (a doomed
           attempt) made much harder.

       ·   Linux

           ·       Long doubles should now work (see INSTALL).

           ·       Linux previously had problems related to sock­
                   addrlen when using accept(), recvfrom() (in
                   Perl: recv()), getpeername(), and getsock­

       ·   NetBSD/threads: try installing the GNU pth (should be
           in the packages collection, or
           http://www.gnu.org/software/pth/), and Configure with

       ·   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
           14.5.0 and GNU C++/GNU Tools 2.0.1 or later.  The Perl
           pack function now maps overflowed values to +infinity
           and underflowed values to -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).  Compiling with gcc still not
           recommended because buggy code results, even with gcc

       ·   Unicos

           Fixed various alignment problems that lead into core
           dumps either during build or later; no longer dies on
           math errors at runtime; now using full quad integers
           (64 bits), previously was using only 46 bit integers
           for speed.

       ·   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

           The tainting of %ENV elements via "keys" or "values"
           File access tests now use current process privileges
           rather than the user's default privileges, which could
           sometimes result in a mismatch between reported access
           and actual access.  This improvement is only available
           on VMS v6.0 and later.

           There is a new "kill" implementation based on
           "sys$sigprc" that allows older VMS systems (pre-7.0)
           to use "kill" to send signals rather than simply force
           exit.  This implementation also allows later systems
           to call "kill" from within a signal handler.

           Iterative logical name translations are now limited to
           10 iterations in imitation of SHOW LOGICAL and other
           OpenVMS facilities.

       ·   Windows

           ·       Signal handling now works better than it used
                   to.  It is now implemented using a Windows
                   message loop, and is therefore less prone to
                   random crashes.

           ·       fork() emulation is now more robust, but still
                   continues to have a few esoteric 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::File::new_tmpfile() is no longer limited
                   to 32767 invocations per-process.

           ·       Better chdir() return value for a non-existent

           ·       Compiling perl using the 64-bit Platform SDK
                   tools is now supported.

           ·       The Win32::SetChildShowWindow() builtin can be
                   used to control the visibility of windows cre­
                   ated by child processes.  See Win32 for

           ·       Non-blocking waits for child processes (or
                   no longer work correctly.  For example, "sys­
                   tem("nmake /nologo", @args)" will now attempt
                   to run the file "nmake /nologo" and will fail
                   when such a file isn't found.  On the other
                   hand, perl will now execute code such as "sys­
                   tem("c:/Program Files/MyApp/foo.exe", @args)"

           ·       The perl header files no longer suppress com­
                   mon warnings from the Microsoft Visual C++
                   compiler.  This means that additional warnings
                   may now 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
                   those generated by the other supported compil­
                   ers (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 cor­
                   rectly propagated to child processes. [561]

           ·       New %ENV entries now propagate to subpro­
                   cesses. [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.

           ·       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 of c:\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 run concurrently. (Still 16M per
                   thread.) [561]

New or Changed Diagnostics

       Please see perldiag for more details.

       ·   Ambiguous range in the transliteration operator (like
           a-z-9) now gives a warning.

       ·   chdir("") and chdir(undef) now give a deprecation
           warning because they cause 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 your Perl with debugging, you can use the -DT
           [561] and -DR options to trace tokenising and to add
           reference counts to displaying variables, respec­

       ·   The lexical warnings category "deprecated" is no
           longer a sub-category of the "syntax" category. It is
           now a top-level category in its own right.

       ·   Unadorned dump() will now give a warning suggesting to
           use explicit CORE::dump() if that's what really is

       ·   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 hopefully easier to understand both because the
           error message now comes before the failed regex and
           because the point of failure is now clearly marked by
           a "<-- HERE" marker.

       ·   Various I/O (and socket) functions like binmode(),
           close(), and so forth now more consistently warn if
           they are used illogically either on a yet unopened or
           on an already closed filehandle (or socket).

       ·   Using lstat() on a filehandle now gives a warning.
           (It's a non-sensical thing to do.)

       ·   The "-M" and "-m" options now warn if you didn't sup­
           ply the module name.

       ·   If you in "use" specify a required minimum version,
           modules matching the name and but not defining a $VER­
           SION will cause a fatal failure.

       ·   Using negative offset for vec() in lvalue context is
           now a warnable offense.
           prototype characters.

       ·   If an attempt to use a (non-blessed) reference as an
           array index is 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 evaled code.

       ·   If you try to "pack" in perlfunc a number less than 0
           or larger than 255 using the "C" format you will get
           an optional warning.  Similarly for 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 inte­

       ·   Warnings relating to the use of PerlIO have been

       ·   Certain regex modifiers such as "(?o)" make sense only
           if applied to the entire regex.  You will get an
           optional warning if you try to do otherwise.

       ·   Variable length lookbehind has not yet been imple­
           mented, trying to use 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 feature have been added.

       ·   Self-ties of arrays and hashes are not supported and
           fatal errors will 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

       ·   Malformed Unicode encodings (UTF-8 and UTF-16) cause a
           lot of warnings, ad doestrying to use UTF-16 surro­
           gates (which are unimplemented).

       ·   perlapi.pod (a companion to perlguts) now attempts to
           document the internal API.

       ·   You can now build a really minimal perl called microp­
           erl.  Building microperl does not require even running
           Configure; "make -f Makefile.micro" should be enough.
           Beware: microperl makes many assumptions, some of
           which may be too bold; the resulting executable may
           crash or otherwise misbehave in wondrous ways.  For
           careful hackers only.

       ·   Added rsignal(), whichsig(), do_join(), op_clear,
           op_null, ptr_table_clear(), ptr_table_free(),
           sv_setref_uv(), and several UTF-8 interfaces to the
           publicised API.  For the full list of the available
           APIs see perlapi.

       ·   Made possible to propagate customised exceptions via

       ·   Now xsubs can have attributes just like subs.  (Well,
           at least the built-in attributes.)

       ·   dTHR and djSP have been obsoleted; the former removed
           (because it's a no-op) and the latter replaced with

       ·   PERL_OBJECT has been completely removed.

       ·   The MAGIC constants (e.g. 'P') have been macrofied
           (e.g. "PERL_MAGIC_TIED") for better source code read­
           ability and maintainability.

       ·   The regex compiler now maintains a structure that
           identifies nodes in the compiled bytecode with the
           corresponding syntactic features of the original regex
           expression.  The information is attached to the new
           "offsets" member of the "struct regexp". See perlde­
           bguts for more complete information.

       ·   The C code has been made much more "gcc -Wall" clean.
           Some warning messages still remain in some platforms,
           so if you are compiling with gcc you may see some
           warnings about dubious practices.  The warnings are
           being worked on.

       ·   perly.c, sv.c, and sv.h have now been extensively com­

       ·   Documentation on how to use the Perl source repository
           has been added to Porting/repository.pod.

       nerability.  See
       for more information.

       The problem was caused by Perl trying to report a sus­
       pected security exploit attempt using an external program,
       /bin/mail.  On Linux platforms the /bin/mail program had
       an undocumented feature which when combined with suidperl
       gave access to a root shell, resulting in a serious com­
       promise instead of reporting the exploit attempt.  If you
       don't have /bin/mail, or if you have 'safe setuid
       scripts', or if suidperl is not installed, you are safe.

       The exploit attempt reporting feature has been completely
       removed from Perl 5.8.0 (and the maintenance release
       5.6.1, and it was removed also from all the Perl 5.7
       releases), so that particular vulnerability isn't there
       anymore.  However, further security vulnerabilities are,
       unfortunately, always possible.  The suidperl functional­
       ity is most probably going to be removed in Perl 5.10.  In
       any case, suidperl should only be used by security experts
       who know exactly what they are doing and why they are
       using suidperl instead of some other solution such as sudo
       ( see http://www.courtesan.com/sudo/ ).

New Tests

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

       Because of the large number of tests, running the regres­
       sion suite will take considerably longer time than it used
       to: expect the suite to take up to 4-5 times longer to run
       than in perl 5.6.  On a really fast 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 moved to 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 contin­
       ues to be highly experimental.  Use in production environ­
       ments is discouraged.
       Some extensions like mod_perl are known to have issues
       with `largefiles', a change brought by Perl 5.6.0 in which
       file offsets default to 64 bits wide, where supported.
       Modules may fail to compile at all, or they may compile
       and work incorrectly.  Currently, there is no good solu­
       tion for the problem, but Configure now provides appropri­
       ate non-largefile ccflags, ldflags, libswanted, and libs
       in the %Config hash (e.g., $Config{ccflags_nolargefiles})
       so the extensions that are having problems can try config­
       uring themselves without the largefileness.  This is
       admittedly not a clean solution, and the solution may not
       even work at all.  One potential failure is whether one
       can (or, if one can, whether it's a good idea to) link
       together 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 to modify only lvalue elements inside the loops.)
       You can see the correct 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

       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.


       You may get errors like 'Undefined symbol "Perl_get_sv"'
       or "can't resolve symbol 'Perl_get_sv'", or the symbol may
       be "Perl_sv_2pv".  This probably means that you are trying
       to use an older shared Perl library (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
       those directories.
       will get a fatal error even from an attempt).

       A change to self-tying of globs has caused them to be
       recursively referenced (see: "Two-Phased Garbage Collec­
       tion" in perlobj).  You will now need an explicit untie to
       destroy a self-tied glob.  This behaviour may be fixed at
       a later date.

       Self-tying of scalars and IO thingies works.


       If this test fails, it indicates that your libc (C
       library) is not threadsafe.  This particular test stress
       tests the localtime() call to find 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
       expected to be removed.  You should migrate your code to

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

        ../ext/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-
        ../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
       threads are considered fundamentally broken.  (Basically
       what happens is that competing threads can corrupt shared
       global state, one good example being regular expression
       engine's state.)

       Timing problems


           ./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 for
       tied/magical arrays and hashes such autovivification does
       not happen because there is currently no way to catch the
       reference creation.  The same problem affects slicing over
       non-existent indices/keys of a tied/magical array/hash.

       Unicode in package/class and subroutine names does not

       One can have Unicode in identifier names, but not in pack­
       age/class or subroutine names.  While some limited func­
       tionality towards this does exist as of Perl 5.8.0, that
       is more accidental than designed; use of Unicode for the
       said purposes is unsupported.

       One reason of this unfinishedness is its (currently)
       inherent unportability: since both package names and sub­
       routine names may need to be mapped to file and directory
       names, the Unicode capability of the filesystem becomes
       important-- and there unfortunately aren't portable

Platform Specific Problems


       ·   If using the AIX native make command, instead of just
           "make" issue "make all".  In some setups the former
           has been known to spuriously also try to run "make
           install".  Alternatively, you may want to use GNU

       ·   In AIX 4.2, Perl extensions that use C++ functions
           that use statics may have problems in that the statics
           are not getting initialized.  In newer AIX releases,
           this has been solved by linking Perl with the libC_r
           library, but unfortunately in AIX 4.2 the said library
           has an obscure bug where the various functions related
           to time (such as time() and gettimeofday()) return
           broken values, and therefore in AIX 4.2 Perl is not
           linked against libC_r.

       ·   vac May Produce Buggy Code For Perl

           The AIX C compiler vac version may produce
           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 failing in a Linux/alpha or *BSD/Alpha, it's proba­
       bly time to upgrade your gcc.  gccs prior to 2.95.3 are
       definitely not good enough, and gcc 3.1 may be even bet­
       ter.  (RedHat Linux/alpha with gcc 3.1 reported no prob­
       lems, as did Linux 2.4.18 with gcc 2.95.4.)  (In Tru64, it
       is preferable to use the bundled C compiler.)


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


       The following tests fail on 5.8.0 Perl in BeOS Personal

        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 is detailed
       in here: http://sources.redhat.com/ml/cyg­

       Cygwin ndbm tests fail on FAT

       One can build but not install (or test the build of) the
       NDBM_File on FAT filesystems.  Installation (or build) on
       NTFS works fine.  If one attempts the test on a FAT
       install (or build) the following failures 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/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 long filenames, but there are a few more if
       running under dosemu because of limitations (and maybe
       bugs) of dosemu:

        t/comp/cpp...........................FAILED at test 3

       and a few lib/ExtUtils tests, and several hundred
       Encode/t/Aliases.t failures that work fine with long file­
       names.  So you really might prefer native builds and long

       FreeBSD built with ithreads coredumps reading large direc­

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

       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 cor­
       rectly when being matched case-insensitively.  Apparently
       this problem has been fixed in the 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 or compiler may fail
       the List::Util test ext/List/Util/t/shuffle.t by dumping
       core.  This seems to be a compiler error since if compiled
       with gcc no core dump ensues, and no failures have been
       seen on the said test on any other platform.

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

       The cure is to drop optimization level (Configure -Dopti­

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

       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 of warnings about the broken locales of Mac OS X.

       The following tests are known to fail in Mac OS X 10.1.5
       because of buggy (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 see t/op/stat.t subtest #9 fail.  This is caused
       by Darwin's UFS not supporting inode change time.

       Also the ext/POSIX/t/posix.t subtest #10 fails but it is
       skipped for now because the failure is Apple's fault, not
       Perl's (blocked signals are 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 local­
       time() call is found to be threadunsafe.)

       Mac OS X dyld undefined symbols

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

           dyld: perl Undefined symbols

       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 rea­
       son "make install" doesn't always completely overwrite the
       files in /Library/Perl.  You can move the old Perl shared
       library out of the way like this:

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

        ../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',0" incorrectly produces 0.000000e+0 instead of

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


       The socketpair tests are known to be unhappy in SCO

        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 may experience failures (the test core dumping) in
       lib/locale.t.  The suggested cure is to upgrade your

       Solaris x86 Fails Tests With -Duse64bitint

       The following tests are known to fail in Solaris x86 with
       Perl configured 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:

        ../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 the signedness handling of
       the C compiler, as do the 64bitint, arith, and pow fail­
       ures.  Most of the rest point at problems with SysV IPC.

       Term::ReadKey not working on Win32

       Use Term::ReadKey 2.20 or later.


       ·   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 UNI­
           COS/mk.  You can ignore the error, but it does cause a
           slight problem: you cannot fully benefit from the h2ph
           utility (see h2ph) that can be used to convert C head­
           ers to Perl libraries, mainly used to be able to
           access from Perl the constants defined using C prepro­
           cessor, cpp.  Because of the 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),
           the getgrent(), getgrnam(), and getgrgid() functions
           cannot return the list of the group members due to a
           bug in the multithreaded support of UNICOS/mk.  What
           this means is that in list context the functions will
           return only three values, not four.


       porting work.


       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 much better than it was in 5.6.0; it's just that
       so many new modules and tests have been added.

        Failed Test                   Stat Wstat Total Fail  Failed  List of Failed
        ../ext/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

       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 and printf formats).  The pat, tr,
       and fold failures are genuine Perl problems caused by
       EBCDIC (and in the pat and fold cases, combining that with
       Unicode).  The Constant and Embed are probably problems in
       the tests (since they test Perl's ability to build exten­
       sions, and that seems to be working reasonably well.)

       Unicode Support on EBCDIC Still Spotty

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

       Seen In Perl 5.7 But Gone Now

       case) just before 5.8.0.  The main rationale was to have
       all core PerlIO layers to have all lowercase names.  The
       "plugins" are named as usual, for example "Per­

       The "threads::shared::queue" and
       "threads::shared::semaphore" were renamed as
       "Thread::Queue" and "Thread::Semaphore" just before 5.8.0.
       The main rationale was to have thread modules to obey nor­
       mal naming, "Thread::" (the "threads" and
       "threads::shared" themselves are more 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
       articles recently posted to the comp.lang.perl.misc news­
       group and the perl bug database at http://bugs.perl.org/ .
       There may also be information at http://www.perl.com/ ,
       the Perl Home Page.

       If you believe you have an unreported bug, please run the
       perlbug program included with your release.  Be sure to
       trim your bug down to a tiny but sufficient test case.
       Your bug report, along with the output of "perl -V", will
       be sent off to perlbug@perl.org to be analysed by the Perl
       porting team.


       The Changes file for exhaustive details on what changed.

       The INSTALL file for how to build Perl.

       The README file for general stuff.

       The Artistic and Copying files for copyright information.


       Written by Jarkko Hietaniemi <jhi@iki.fi>.

perl v5.8.1                 2003-09-02             PERL58DELTA(1)

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