PERLDELTA(1)     Perl Programmers Reference Guide    PERLDELTA(1)

NNAAMMEE
       perldelta - what's new for perl5.005

DDEESSCCRRIIPPTTIIOONN
       This document describes differences between the 5.004
       release and this one.

AAbboouutt tthhee nneeww vveerrssiioonniinngg ssyysstteemm
       Perl is now developed on two tracks: a maintenance track
       that makes small, safe updates to released production
       versions with emphasis on compatibility; and a development
       track that pursues more aggressive evolution.  Maintenance
       releases (which should be considered production quality)
       have subversion numbers that run from 1 to 49, and
       development releases (which should be considered "alpha"
       quality) run from 50 to 99.

       Perl 5.005 is the combined product of the new dual-track
       development scheme.

IInnccoommppaattiibbllee CChhaannggeess
       WWAARRNNIINNGG::  TThhiiss vveerrssiioonn iiss nnoott bbiinnaarryy ccoommppaattiibbllee wwiitthh PPeerrll
       55..000044..

       Starting with Perl 5.004_50 there were many deep and far-
       reaching changes to the language internals.  If you have
       dynamically loaded extensions that you built under perl
       5.003 or 5.004, you can continue to use them with 5.004,
       but you will need to rebuild and reinstall those
       extensions to use them 5.005.  See the INSTALL manpage for
       detailed instructions on how to upgrade.

       DDeeffaauulltt iinnssttaallllaattiioonn ssttrruuccttuurree hhaass cchhaannggeedd

       The new Configure defaults are designed to allow a smooth
       upgrade from 5.004 to 5.005, but you should read the
       INSTALL manpage for a detailed discussion of the changes
       in order to adapt them to your system.

       PPeerrll SSoouurrccee CCoommppaattiibbiilliittyy

       When none of the experimental features are enabled, there
       should be very few user-visible Perl source compatibility
       issues.

       If threads are enabled, then some caveats apply. @_ and $_
       become lexical variables.  The effect of this should be
       largely transparent to the user, but there are some
       boundary conditions under which user will need to be aware
       of the issues.  For example, local(@_) results in a "Can't
       localize lexical variable @_ ..." message.  This may be
       enabled in a future version.

       Some new keywords have been introduced.  These are
       generally expected to have very little impact on
       compatibility.  See the section on New INIT keyword, the
       section on New lock keyword, and the section on New qr//
       operator.

       Certain barewords are now reserved.  Use of these will
       provoke a warning if you have asked for them with the -w
       switch.  See the our manpage is now a reserved word.

       CC SSoouurrccee CCoommppaattiibbiilliittyy

       There have been a large number of changes in the internals
       to support the new features in this release.

       Core sources now require ANSI C compiler
           An ANSI C compiler is now rreeqquuiirreedd to build perl.  See
           INSTALL.

       All Perl global variables must now be referenced with an
           explicit prefix
           All Perl global variables that are visible for use by
           extensions now have a PL_ prefix.  New extensions
           should not refer to perl globals by their unqualified
           names.  To preserve sanity, we provide limited
           backward compatibility for globals that are being
           widely used like sv_undef and na (which should now be
           written as PL_sv_undef, PL_na etc.)

           If you find that your XS extension does not compile
           anymore because a perl global is not visible, try
           adding a PL_ prefix to the global and rebuild.

           It is strongly recommended that all functions in the
           Perl API that don't begin with perl be referenced with
           a Perl_ prefix.  The bare function names without the
           Perl_ prefix are supported with macros, but this
           support may cease in a future release.

           See the section on API LISTING in the perlguts
           manpage.

       Enabling threads has source compatibility issues
           Perl built with threading enabled requires extensions
           to use the new dTHR macro to initialize the handle to
           access per-thread data.  If you see a compiler error
           that talks about the variable thr not being declared
           (when building a module that has XS code),  you need
           to add dTHR; at the beginning of the block that
           elicited the error.

           The API function perl_get_sv("@",FALSE) should be used
           instead of directly accessing perl globals as
           GvSV(errgv).  The API call is backward compatible with
           existing perls and provides source compatibility with
           threading is enabled.

           See the section on C Source Compatibility for more
           information.

       BBiinnaarryy CCoommppaattiibbiilliittyy

       This version is NOT binary compatible with older versions.
       All extensions will need to be recompiled.  Further
       binaries built with threads enabled are incompatible with
       binaries built without.  This should largely be
       transparent to the user, as all binary incompatible
       configurations have their own unique architecture name,
       and extension binaries get installed at unique locations.
       This allows coexistence of several configurations in the
       same directory hierarchy.  See INSTALL.

       SSeeccuurriittyy ffiixxeess mmaayy aaffffeecctt ccoommppaattiibbiilliittyy

       A few taint leaks and taint omissions have been corrected.
       This may lead to "failure" of scripts that used to work
       with older versions.  Compiling with -DINCOMPLETE_TAINTS
       provides a perl with minimal amounts of changes to the
       tainting behavior.  But note that the resulting perl will
       have known insecurities.

       Oneliners with the -e switch do not create temporary files
       anymore.

       RReellaaxxeedd nneeww mmaannddaattoorryy wwaarrnniinnggss iinnttrroodduucceedd iinn 55..000044

       Many new warnings that were introduced in 5.004 have been
       made optional.  Some of these warnings are still present,
       but perl's new features make them less often a problem.
       See the section on New Diagnostics.

       LLiicceennssiinngg

       Perl has a new Social Contract for contributors.  See
       Porting/Contract.

       The license included in much of the Perl documentation has
       changed.  Most of the Perl documentation was previously
       under the implicit GNU General Public License or the
       Artistic License (at the user's choice).  Now much of the
       documentation unambigously states the terms under which it
       may be distributed.  Those terms are in general much less
       restrictive than the GNU GPL.  See the perl manpage and
       the individual perl man pages listed therein.

CCoorree CChhaannggeess
       TThhrreeaaddss

       WARNING: Threading is considered an eexxppeerriimmeennttaall feature.
       Details of the implementation may change without notice.
       There are known limitations and some bugs.  These are
       expected to be fixed in future versions.

       See the README.threads manpage.

       Mach cthreads (NEXTSTEP, OPENSTEP, Rhapsody) are now
       supported by the Thread extension.

       CCoommppiilleerr

       WARNING: The Compiler and related tools are considered
       eexxppeerriimmeennttaall.  Features may change without notice, and
       there are known limitations and bugs.  Since the compiler
       is fully external to perl, the default configuration will
       build and install it.

       The Compiler produces three different types of
       transformations of a perl program.  The C backend
       generates C code that captures perl's state just before
       execution begins.  It eliminates the compile-time
       overheads of the regular perl interpreter, but the run-
       time performance remains comparatively the same.  The CC
       backend generates optimized C code equivalent to the code
       path at run-time.  The CC backend has greater potential
       for big optimizations, but only a few optimizations are
       implemented currently.  The Bytecode backend generates a
       platform independent bytecode representation of the
       interpreter's state just before execution.  Thus, the
       Bytecode back end also eliminates much of the compilation
       overhead of the interpreter.

       The compiler comes with several valuable utilities.

       B::Lint is an experimental module to detect and warn about
       suspicious code, especially the cases that the -w switch
       does not detect.

       B::Deparse can be used to demystify perl code, and
       understand how perl optimizes certain constructs.

       B::Xref generates cross reference reports of all
       definition and use of variables, subroutines and formats
       in a program.

       B::Showlex show the lexical variables used by a subroutine
       or file at a glance.

       perlcc is a simple frontend for compiling perl.

       See ext/B/README, the section on B, and the respective
       compiler modules.

       RReegguullaarr EExxpprreessssiioonnss

       Perl's regular expression engine has been seriously
       overhauled, and many new constructs are supported.
       Several bugs have been fixed.

       Here is an itemized summary:

       Many new and improved optimizations
           Changes in the RE engine:

                   Unneeded nodes removed;
                   Substrings merged together;
                   New types of nodes to process (SUBEXPR)* and similar expressions
                       quickly, used if the SUBEXPR has no side effects and matches
                       strings of the same length;
                   Better optimizations by lookup for constant substrings;
                   Better search for constants substrings anchored by $ ;

           Changes in Perl code using RE engine:

                   More optimizations to s/longer/short/;
                   study() was not working;
                   /blah/ may be optimized to an analogue of index() if $& $` $' not seen;
                   Unneeded copying of matched-against string removed;
                   Only matched part of the string is copying if $` $' were not seen;

       Many bug fixes
           Note that only the major bug fixes are listed here.
           See Changes for others.

                   Backtracking might not restore start of $3.
                   No feedback if max count for * or + on "complex" subexpression
                       was reached, similarly (but at compile time) for {3,34567}
                   Primitive restrictions on max count introduced to decrease a
                       possibility of a segfault;
                   (ZERO-LENGTH)* could segfault;
                   (ZERO-LENGTH)* was prohibited;
                   Long REs were not allowed;
                   /RE/g could skip matches at the same position after a
                     zero-length match;

       New regular expression constructs
           The following new syntax elements are supported:

                   (?<=RE)
                   (?<!RE)
                   (?{ CODE })
                   (?i-x)
                   (?i:RE)
                   (?(COND)YES_RE|NO_RE)
                   (?>RE)
                   \z

       New operator for precompiled regular expressions
           See the section on New qr// operator.

       Other improvements

                   Better debugging output (possibly with colors),
                       even from non-debugging Perl;
                   RE engine code now looks like C, not like assembler;
                   Behaviour of RE modifiable by `use re' directive;
                   Improved documentation;
                   Test suite significantly extended;
                   Syntax [:^upper:] etc., reserved inside character classes;

       Incompatible changes

                   (?i) localized inside enclosing group;
                   $( is not interpolated into RE any more;
                   /RE/g may match at the same position (with non-zero length)
                       after a zero-length match (bug fix).

       See the perlre manpage and the perlop manpage.

       IImmpprroovveedd malloc()

       See banner at the beginning of malloc.c for details.

       QQuuiicckkssoorrtt iiss iinntteerrnnaallllyy iimmpplleemmeenntteedd

       Perl now contains its own highly optimized qsort()
       routine.  The new qsort() is resistant to inconsistent
       comparison functions, so Perl's sort() will not provoke
       coredumps any more when given poorly written sort
       subroutines.  (Some C library qsort()s that were being
       used before used to have this problem.)  In our testing,
       the new qsort() required the minimal number of pair-wise
       compares on average, among all known qsort()
       implementations.

       See perlfunc/sort.

       RReelliiaabbllee ssiiggnnaallss

       Perl's signal handling is susceptible to random crashes,
       because signals arrive asynchronously, and the Perl
       runtime is not reentrant at arbitrary times.

       However, one experimental implementation of reliable
       signals is available when threads are enabled.  See
       Thread::Signal.  Also see INSTALL for how to build a Perl
       capable of threads.

       RReelliiaabbllee ssttaacckk ppooiinntteerrss

       The internals now reallocate the perl stack only at
       predictable times.  In particular, magic calls never
       trigger reallocations of the stack, because all reentrancy
       of the runtime is handled using a "stack of stacks".  This
       should improve reliability of cached stack pointers in the
       internals and in XSUBs.

       MMoorree ggeenneerroouuss ttrreeaattmmeenntt ooff ccaarrrriiaaggee rreettuurrnnss

       Perl used to complain if it encountered literal carriage
       returns in scripts.  Now they are mostly treated like
       whitespace within program text.  Inside string literals
       and here documents, literal carriage returns are ignored
       if they occur paired with linefeeds, or get interpreted as
       whitespace if they stand alone.  This behavior means that
       literal carriage returns in files should be avoided.  You
       can get the older, more compatible (but less generous)
       behavior by defining the preprocessor symbol
       PERL_STRICT_CR when building perl.  Of course, all this
       has nothing whatever to do with how escapes like \r are
       handled within strings.

       Note that this doesn't somehow magically allow you to keep
       all text files in DOS format.  The generous treatment only
       applies to files that perl itself parses.  If your C
       compiler doesn't allow carriage returns in files, you may
       still be unable to build modules that need a C compiler.

       MMeemmoorryy lleeaakkss

       substr, pos and vec don't leak memory anymore when used in
       lvalue context.  Many small leaks that impacted
       applications that embed multiple interpreters have been
       fixed.

       BBeetttteerr ssuuppppoorrtt ffoorr mmuullttiippllee iinntteerrpprreetteerrss

       The build-time option -DMULTIPLICITY has had many of the
       details reworked.  Some previously global variables that
       should have been per-interpreter now are.  With care, this
       allows interpreters to call each other.  See the
       PerlInterp extension on CPAN.

       BBeehhaavviioorr ooff local() on array and hash elements is now
       well-defined

       See the section on Temporary Values via local() in the
       perlsub manpage.

       %%!! is transparently tied to the the Errno manpage module

       See the perlvar manpage, and the Errno manpage.

       PPsseeuuddoo--hhaasshheess aarree ssuuppppoorrtteedd

       See the perlref manpage.

       EEXXPPRR ffoorreeaacchh EEXXPPRR is supported

       See the perlsyn manpage.

       KKeeyywwoorrddss ccaann bbee gglloobbaallllyy oovveerrrriiddddeenn

       See the perlsub manpage.

       $$^^EE is meaningful on Win32

       See the perlvar manpage.

       ffoorreeaacchh ((11....11000000000000)) optimized

       foreach (1..1000000) is now optimized into a counting
       loop.  It does not try to allocate a 1000000-size list
       anymore.

       FFoooo:::: can be used as implicitly quoted package name

       Barewords caused unintuitive behavior when a subroutine
       with the same name as a package happened to be defined.
       Thus, new Foo @args, use the result of the call to Foo()
       instead of Foo being treated as a literal.  The
       recommended way to write barewords in the indirect object
       slot is new Foo:: @args.  Note that the method new() is
       called with a first argument of Foo, not Foo:: when you do
       that.

       eexxiissttss $$FFoooo::::{{BBaarr::::}} tests existence of a package

       It was impossible to test for the existence of a package
       without actually creating it before.  Now exists
       $Foo::{Bar::} can be used to test if the Foo::Bar
       namespace has been created.

       BBeetttteerr llooccaallee ssuuppppoorrtt

       See the perllocale manpage.

       EExxppeerriimmeennttaall ssuuppppoorrtt ffoorr 6644--bbiitt ppllaattffoorrmmss

       Perl5 has always had 64-bit support on systems with 64-bit
       longs.  Starting with 5.005, the beginnings of
       experimental support for systems with 32-bit long and
       64-bit 'long long' integers has been added.  If you add
       -DUSE_LONG_LONG to your ccflags in config.sh (or manually
       define it in perl.h) then perl will be built with 'long
       long' support.  There will be many compiler warnings, and
       the resultant perl may not work on all systems.  There are
       many other issues related to third-party extensions and
       libraries.  This option exists to allow people to work on
       those issues.

       prototype() returns useful results on builtins

       See the prototype entry in the perlfunc manpage.

       EExxtteennddeedd ssuuppppoorrtt ffoorr eexxcceeppttiioonn hhaannddlliinngg

       die() now accepts a reference value, and $@ gets set to
       that value in exception traps.  This makes it possible to
       propagate exception objects.  This is an undocumented
       eexxppeerriimmeennttaall feature.

       RRee--bblleessssiinngg iinn DESTROY() supported for chaining DESTROY()
       methods

       See the Destructors entry in the perlobj manpage.

       AAllll pprriinnttff format conversions are handled internally

       See the printf entry in the perlfunc manpage.

       NNeeww IINNIITT keyword

       INIT subs are like BEGIN and END, but they get run just
       before the perl runtime begins execution.  e.g., the Perl
       Compiler makes use of INIT blocks to initialize and
       resolve pointers to XSUBs.

       NNeeww lloocckk keyword

       The lock keyword is the fundamental synchronization
       primitive in threaded perl.  When threads are not enabled,
       it is currently a noop.

       To minimize impact on source compatibility this keyword is
       "weak", i.e., any user-defined subroutine of the same name
       overrides it, unless a use Thread has been seen.

       NNeeww qqrr//// operator

       The qr// operator, which is syntactically similar to the
       other quote-like operators, is used to create precompiled
       regular expressions.  This compiled form can now be
       explicitly passed around in variables, and interpolated in
       other regular expressions.  See the perlop manpage.

       oouurr is now a reserved word

       Calling a subroutine with the name our will now provoke a
       warning when using the -w switch.

       TTiieedd aarrrraayyss aarree nnooww ffuullllyy ssuuppppoorrtteedd

       See the Tie::Array manpage.

       TTiieedd hhaannddlleess ssuuppppoorrtt iiss bbeetttteerr

       Several missing hooks have been added.  There is also a
       new base class for TIEARRAY implementations.  See the
       Tie::Array manpage.

       44tthh aarrgguummeenntt ttoo ssuubbssttrr

       substr() can now both return and replace in one operation.
       The optional 4th argument is the replacement string.  See
       the substr entry in the perlfunc manpage.

       NNeeggaattiivvee LLEENNGGTTHH aarrgguummeenntt ttoo sspplliiccee

       splice() with a negative LENGTH argument now work similar
       to what the LENGTH did for substr().  Previously a
       negative LENGTH was treated as 0.  See the splice entry in
       the perlfunc manpage.

       MMaaggiicc llvvaalluueess aarree nnooww mmoorree mmaaggiiccaall

       When you say something like substr($x, 5) = "hi", the
       scalar returned by substr() is special, in that any
       modifications to it affect $x.  (This is called a 'magic
       lvalue' because an 'lvalue' is something on the left side
       of an assignment.)  Normally, this is exactly what you
       would expect to happen, but Perl uses the same magic if
       you use substr(), pos(), or vec() in a context where they
       might be modified, like taking a reference with \ or as an
       argument to a sub that modifies @_.  In previous versions,
       this 'magic' only went one way, but now changes to the
       scalar the magic refers to ($x in the above example)
       affect the magic lvalue too. For instance, this code now
       acts differently:

           $x = "hello";
           sub printit {
               $x = "g'bye";
               print $_[0], "\n";
           }
           printit(substr($x, 0, 5));

       In previous versions, this would print "hello", but it now
       prints "g'bye".

       <<b><><b>> nnooww rreeaaddss iinn rreeccoorrddss

       If $/ is a referenence to an integer, or a scalar that
       holds an integer, <> will read in records instead of
       lines. For more info, see the section on $/ in the perlvar
       manpage.

       pack() format 'Z' supported

       The new format type 'Z' is useful for packing and
       unpacking null-terminated strings.  See the section on
       pack in the perlfunc manpage.

SSiiggnniiffiiccaanntt bbuugg ffiixxeess
       <<b><HHAANNDDLLEE><b>> oonn eemmppttyy ffiilleess

       With $/ set to undef, slurping an empty file returns a
       string of zero length (instead of undef, as it used to)
       for the first time the HANDLE is read.  Subsequent reads
       yield undef.

       This means that the following will append "foo" to an
       empty file (it used to not do anything before):

           perl -0777 -pi -e 's/^/foo/' empty_file

       Note that the behavior of:

           perl -pi -e 's/^/foo/' empty_file

       is unchanged (it continues to leave the file empty).

SSuuppppoorrtteedd PPllaattffoorrmmss
       Configure has many incremental improvements.  Site-wide
       policy for building perl can now be made persistent, via
       Policy.sh.  Configure also records the command-line
       arguments used in config.sh.

       NNeeww PPllaattffoorrmmss

       BeOS is now supported.  See the README.beos manpage.

       DOS is now supported under the DJGPP tools.  See the
       README.dos manpage.

       GNU/Hurd is now supported.

       MiNT is now supported.  See the README.mint manpage.

       MPE/iX is now supported.  See the README.mpeix manpage.

       MVS (aka OS390, aka Open Edition) is now supported.  See
       the README.os390 manpage.

       Stratus VOS is now supported.  See the README.vos manpage.

       CChhaannggeess iinn eexxiissttiinngg ssuuppppoorrtt

       Win32 support has been vastly enhanced.  Support for Perl
       Object, a C++ encapsulation of Perl.  GCC and EGCS are now
       supported on Win32.  See README.win32, aka the perlwin32
       manpage.

       VMS configuration system has been rewritten.  See the
       README.vms manpage.

       The hints files for most Unix platforms have seen
       incremental improvements.

MMoodduulleess aanndd PPrraaggmmaattaa
       NNeeww MMoodduulleess

       B    Perl compiler and tools.  See the section on B.

       Data::Dumper
            A module to pretty print Perl data.  See the
            Data::Dumper manpage.

       Dumpvalue
            A module to dump perl values to the screen. See the
            Dumpvalue manpage.

       Errno
            A module to look up errors more conveniently.  See
            the Errno manpage.

       File::Spec
            A portable API for file operations.

       ExtUtils::Installed
            Query and manage installed modules.

       ExtUtils::Packlist
            Manipulate .packlist files.

       Fatal
            Make functions/builtins succeed or die.

       IPC::SysV
            Constants and other support infrastructure for System
            V IPC operations in perl.

       Test A framework for writing testsuites.

       Tie::Array
            Base class for tied arrays.

       Tie::Handle
            Base class for tied handles.

       Thread
            Perl thread creation, manipulation, and support.

       attrs
            Set subroutine attributes.

       fields
            Compile-time class fields.

       re   Various pragmata to control behavior of regular
            expressions.

       CChhaannggeess iinn eexxiissttiinngg mmoodduulleess

       Benchmark
            You can now run tests for n seconds instead of
            guessing the right number of tests to run: e.g.
            timethese(-5, ...) will run each of the codes for at
            least 5 CPU seconds.  Zero as the "number of
            repetitions" means "for at least 3 CPU seconds".  The
            output format has also changed.  For example:

            use
            Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})

            will now output something like this:

            Benchmark: running a, b, each for at least 5 CPU
            seconds...
                     a:  5 wallclock secs ( 5.77 usr +  0.00 sys
            =  5.77 CPU) @ 200551.91/s (n=1156516)
                     b:  4 wallclock secs ( 5.00 usr +  0.02 sys
            =  5.02 CPU) @ 159605.18/s (n=800686)

            New features: "each for at least N CPU seconds...",
            "wallclock secs", and the "@ operations/CPU second
            (n=operations)".

       Carp Carp has a new function cluck(). cluck() warns, like
            carp(), but also adds a stack backtrace to the error
            message, like confess().

       CGI  CGI has been updated to version 2.42.

       Fcntl
            More Fcntl constants added: F_SETLK64, F_SETLKW64,
            O_LARGEFILE for large (more than 4G) file access (the
            64-bit support is not yet working, though, so no need
            to get overly excited), Free/Net/OpenBSD locking
            behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
            O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and
            O_RDWR.

       Math::Complex
            The accessor methods Re, Im, arg, abs, rho, and
            theta, can now also act as mutators (accessor
            $z->Re(), mutator $z->Re(3)).

       Math::Trig
            A little bit of radial trigonometry (cylindrical and
            spherical) added: radial coordinate conversions and
            the great circle distance.

       POSIX
            POSIX now has its own platform-specific hints files.

       DB_File
            DB_File supports version 2.x of Berkeley DB.  See
            ext/DB_File/Changes.

       MakeMaker
            MakeMaker now supports writing empty makefiles,
            provides a way to specify that site umask() policy
            should be honored.  There is also better support for
            manipulation of .packlist files, and getting
            information about installed modules.

            Extensions that have both architecture-dependent and
            architecture-independent files are now always
            installed completely in the architecture-dependent
            locations.  Previously, the shareable parts were
            shared both across architectures and across perl
            versions and were therefore liable to be overwritten
            with newer versions that might have subtle
            incompatibilities.

       CPAN See <perlmodinstall> and the CPAN manpage.

       Cwd  Cwd::cwd is faster on most platforms.

       Benchmark
            Keeps better time.

UUttiilliittyy CChhaannggeess
       h2ph and related utilities have been vastly overhauled.

       perlcc, a new experimental front end for the compiler is
       available.

       The crude GNU configure emulator is now called
       configure.gnu to avoid trampling on Configure under case-
       insensitive filesystems.

       perldoc used to be rather slow.  The slower features are
       now optional.  In particular, case-insensitive searches
       need the -i switch, and recursive searches need -r.  You
       can set these switches in the PERLDOC environment variable
       to get the old behavior.

DDooccuummeennttaattiioonn CChhaannggeess
       Config.pm now has a glossary of variables.

       Porting/patching.pod has detailed instructions on how to
       create and submit patches for perl.

       the perlport manpage specifies guidelines on how to write
       portably.

       the perlmodinstall manpage describes how to fetch and
       install modules from CPAN sites.

       Some more Perl traps are documented now.  See the perltrap
       manpage.

       the perlopentut manpage gives a tutorial on using open().

       the perlreftut manpage gives a tutorial on references.

       the perlthrtut manpage gives a tutorial on threads.

NNeeww DDiiaaggnnoossttiiccss
       Ambiguous call resolved as CORE::%s(), qualify as such or
            use &
            (W) A subroutine you have declared has the same name
            as a Perl keyword, and you have used the name without
            qualification for calling one or the other.  Perl
            decided to call the builtin because the subroutine is
            not imported.

            To force interpretation as a subroutine call, either
            put an ampersand before the subroutine name, or
            qualify the name with its package.  Alternatively,
            you can import the subroutine (or pretend that it's
            imported with the use subs pragma).

            To silently interpret it as the Perl operator, use
            the CORE:: prefix on the operator (e.g.
            CORE::log($x)) or by declaring the subroutine to be
            an object method (see the attrs manpage).

       Bad index while coercing array into hash
            (F) The index looked up in the hash found as the 0'th
            element of a pseudo-hash is not legal.  Index values
            must be at 1 or greater.  See the perlref manpage.

       Bareword """"%s"""" refers to nonexistent package
            (W) You used a qualified bareword of the form Foo::,
            but the compiler saw no other uses of that namespace
            before that point.  Perhaps you need to predeclare a
            package?

       Can't call method """"%s"""" on an undefined value
            (F) You used the syntax of a method call, but the
            slot filled by the object reference or package name
            contains an undefined value.  Something like this
            will reproduce the error:

                $BADREF = 42;
                process $BADREF 1,2,3;
                $BADREF->process(1,2,3);

       Can't check filesystem of script """"%s"""" for nosuid
            (P) For some reason you can't check the filesystem of
            the script for nosuid.

       Can't coerce array into hash
            (F) You used an array where a hash was expected, but
            the array has no information on how to map from keys
            to array indices.  You can do that only with arrays
            that have a hash reference at index 0.

       Can't goto subroutine from an eval-string
            (F) The "goto subroutine" call can't be used to jump
            out of an eval "string".  (You can use it to jump out
            of an eval {BLOCK}, but you probably don't want to.)

       Can't localize pseudo-hash element
            (F) You said something like local $ar->{'key'}, where
            $ar is a reference to a pseudo-hash.  That hasn't
            been implemented yet, but you can get a similar
            effect by localizing the corresponding array element
            directly -- local $ar->[$ar->[0]{'key'}].

       Can't use %%! because Errno.pm is not available
            (F) The first time the %! hash is used, perl
            automatically loads the Errno.pm module. The Errno
            module is expected to tie the %! hash to provide
            symbolic names for $! errno values.

       Cannot find an opnumber for """"%s""""
            (F) A string of a form CORE::word was given to
            prototype(), but there is no builtin with the name
            word.

       Character class syntax [. .] is reserved for future
            extensions
            (W) Within regular expression character classes ([])
            the syntax beginning with "[." and ending with ".]"
            is reserved for future extensions.  If you need to
            represent those character sequences inside a regular
            expression character class, just quote the square
            brackets with the backslash: "\[." and ".\]".

       Character class syntax [: :] is reserved for future
            extensions
            (W) Within regular expression character classes ([])
            the syntax beginning with "[:" and ending with ":]"
            is reserved for future extensions.  If you need to
            represent those character sequences inside a regular
            expression character class, just quote the square
            brackets with the backslash: "\[:" and ":\]".

       Character class syntax [= =] is reserved for future
            extensions
            (W) Within regular expression character classes ([])
            the syntax beginning with "[=" and ending with "=]"
            is reserved for future extensions.  If you need to
            represent those character sequences inside a regular
            expression character class, just quote the square
            brackets with the backslash: "\[=" and "=\]".

       %s: Eval-group in insecure regular expression
            (F) Perl detected tainted data when trying to compile
            a regular expression that contains the (?{ ... })
            zero-width assertion, which is unsafe.  See the
            section on (?{ code }) in the perlre manpage, and the
            perlsec manpage.

       %s: Eval-group not allowed, use re 'eval'
            (F) A regular expression contained the (?{ ... })
            zero-width assertion, but that construct is only
            allowed when the use re 'eval' pragma is in effect.
            See the section on (?{ code }) in the perlre manpage.

       %s: Eval-group not allowed at run time
            (F) Perl tried to compile a regular expression
            containing the (?{ ... }) zero-width assertion at run
            time, as it would when the pattern contains
            interpolated values.  Since that is a security risk,
            it is not allowed.  If you insist, you may still do
            this by explicitly building the pattern from an
            interpolated string at run time and using that in an
            eval().  See the section on (?{ code }) in the perlre
            manpage.

       Explicit blessing to '' (assuming package main)
            (W) You are blessing a reference to a zero length
            string.  This has the effect of blessing the
            reference into the package main.  This is usually not
            what you want.  Consider providing a default target
            package, e.g. bless($ref, $p || 'MyPackage');

       Illegal hex digit ignored
            (W) You may have tried to use a character other than
            0 - 9 or A - F in a hexadecimal number.
            Interpretation of the hexadecimal number stopped
            before the illegal character.

       No such array field
            (F) You tried to access an array as a hash, but the
            field name used is not defined.  The hash at index 0
            should map all valid field names to array indices for
            that to work.

       No such field """"%s"""" in variable %s of type %s
            (F) You tried to access a field of a typed variable
            where the type does not know about the field name.
            The field names are looked up in the %FIELDS hash in
            the type package at compile time.  The %FIELDS hash
            is usually set up with the 'fields' pragma.

       Out of memory during ridiculously large request
            (F) You can't allocate more than 2^31+"small amount"
            bytes.  This error is most likely to be caused by a
            typo in the Perl program. e.g., $arr[time] instead of
            $arr[$time].

       Range iterator outside integer range
            (F) One (or both) of the numeric arguments to the
            range operator ".."  are outside the range which can
            be represented by integers internally.  One possible
            workaround is to force Perl to use magical string
            increment by prepending "0" to your numbers.

       Recursive inheritance detected while looking for method
            '%s' in package '%s'
            (F) More than 100 levels of inheritance were
            encountered while invoking a method.  Probably
            indicates an unintended loop in your inheritance
            hierarchy.

       Reference found where even-sized list expected
            (W) You gave a single reference where Perl was
            expecting a list with an even number of elements (for
            assignment to a hash). This usually means that you
            used the anon hash constructor when you meant to use
            parens. In any case, a hash requires key/value ppaaiirrss.

                %hash = { one => 1, two => 2, };   # WRONG
                %hash = [ qw/ an anon array / ];   # WRONG
                %hash = ( one => 1, two => 2, );   # right
                %hash = qw( one 1 two 2 );                 # also fine

       Undefined value assigned to typeglob
            (W) An undefined value was assigned to a typeglob, a
            la *foo = undef.  This does nothing.  It's possible
            that you really mean undef *foo.

       Use of reserved word """"%s"""" is deprecated
            (D) The indicated bareword is a reserved word.
            Future versions of perl may use it as a keyword, so
            you're better off either explicitly quoting the word
            in a manner appropriate for its context of use, or
            using a different name altogether.  The warning can
            be suppressed for subroutine names by either adding a
            & prefix, or using a package qualifier, e.g. &our(),
            or Foo::our().

       perl: warning: Setting locale failed.
            (S) The whole warning message will look something
            like:

                   perl: warning: Setting locale failed.
                   perl: warning: Please check that your locale settings:
                           LC_ALL = "En_US",
                           LANG = (unset)
                       are supported and installed on your system.
                   perl: warning: Falling back to the standard locale ("C").

            Exactly what were the failed locale settings varies.
            In the above the settings were that the LC_ALL was
            "En_US" and the LANG had no value.  This error means
            that Perl detected that you and/or your system
            administrator have set up the so-called variable
            system but Perl could not use those settings.  This
            was not dead serious, fortunately: there is a
            "default locale" called "C" that Perl can and will
            use, the script will be run.  Before you really fix
            the problem, however, you will get the same error
            message each time you run Perl.  How to really fix
            the problem can be found in the section on LOCALE
            PROBLEMS in the perllocale manpage.

OObbssoolleettee DDiiaaggnnoossttiiccss
       Can't mktemp()
            (F) The mktemp() routine failed for some reason while
            trying to process a --ee switch.  Maybe your /tmp
            partition is full, or clobbered.

            Removed because --ee doesn't use temporary files any
            more.

       Can't write to temp file for --ee: %s
            (F) The write routine failed for some reason while
            trying to process a --ee switch.  Maybe your /tmp
            partition is full, or clobbered.

            Removed because --ee doesn't use temporary files any
            more.

       Cannot open temporary file
            (F) The create routine failed for some reason while
            trying to process a --ee switch.  Maybe your /tmp
            partition is full, or clobbered.

            Removed because --ee doesn't use temporary files any
            more.

       regexp too big
            (F) The current implementation of regular expressions
            uses shorts as address offsets within a string.
            Unfortunately this means that if the regular
            expression compiles to longer than 32767, it'll blow
            up.  Usually when you want a regular expression this
            big, there is a better way to do it with multiple
            statements.  See the perlre manpage.

CCoonnffiigguurraattiioonn CChhaannggeess
       You can use "Configure -Uinstallusrbinperl" which causes
       installperl to skip installing perl also as /usr/bin/perl.
       This is useful if you prefer not to modify /usr/bin for
       some reason or another but harmful because many scripts
       assume to find Perl in /usr/bin/perl.

BBUUGGSS
       If you find what you think is a bug, you might check the
       headers of recently posted articles in the
       comp.lang.perl.misc newsgroup.  There may also be
       information at http://www.perl.com/perl/, the Perl Home
       Page.

       If you believe you have an unreported bug, please run the
       ppeerrllbbuugg program included with your release.  Make sure you
       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.com> to be analysed by the Perl
       porting team.

SSEEEE AALLSSOO
       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.

HHIISSTTOORRYY
       Written by Gurusamy Sarathy <gsar@umich.edu>, with many
       contributions from The Perl Porters.

       Send omissions or corrections to <perlbug@perl.com>.

27/Mar/1999            perl 5.005, patch 03                     1