NAME
    perldelta - what's new for perl5.005

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

About the new versioning system
    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.

Incompatible Changes
  WARNING:  This version is not binary compatible with Perl 5.004.

    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.

  Default installation structure has changed

    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.

  Perl Source Compatibility

    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
    New `INIT' keyword manpage, the New `lock' keyword manpage, and
    the "/' operator" entry in the New `qr manpage.

    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' is now a reserved word manpage.

  C Source Compatibility

    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 required 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 "API LISTING" entry 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 API Changes for more information manpage.


  Binary Compatibility

    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.

  Security fixes may affect compatibility

    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.

  Relaxed new mandatory warnings introduced in 5.004

    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 New
    Diagnostics manpage.

  Licensing

    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.

Core Changes
  Threads

    WARNING: Threading is considered an experimental 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.

  Compiler

    WARNING: The Compiler and related tools are considered
    experimental. 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 B manpage, and the respective compiler
    modules.

  Regular Expressions

    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 "/' operator" entry in the New `qr manpage.

    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.

  Improved malloc()

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

  Quicksort is internally implemented

    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'.

  Reliable signals

    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.

  Reliable stack pointers

    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.

  More generous treatment of carriage returns

    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 newlines,
    or get interpreted as newlines 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.

  Memory leaks

    `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.

  Better support for multiple interpreters

    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.

  Behavior of 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.

  Pseudo-hashes are supported

    See the perlref manpage.

  `EXPR foreach EXPR' is supported

    See the perlsyn manpage.

  Keywords can be globally overridden

    See the perlsub manpage.

  `$^E' is meaningful on Win32

    See the perlvar manpage.

  `foreach (1..1000000)' optimized

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

  `Foo::' 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.

  `exists $Foo::{Bar::}' 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.

  Better locale support

    See the perllocale manpage.

  Experimental support for 64-bit platforms

    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.

  Extended support for exception handling

    `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 experimental feature.

  Re-blessing in DESTROY() supported for chaining DESTROY() methods

    See the "Destructors" entry in the perlobj manpage.

  All `printf' format conversions are handled internally

    See the "printf" entry in the perlfunc manpage.

  New `INIT' 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.

  New `lock' 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.

  New `qr//' 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.

  `our' is now a reserved word

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

  Tied arrays are now fully supported

    See the Tie::Array manpage.

  Tied handles support is better

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

  4th argument to substr

    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.

  Negative LENGTH argument to splice

    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.

  Magic lvalues are now more magical

    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".

  <> now reads in records

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

Supported Platforms
    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.

  New Platforms

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

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

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

    MVS (OS390) is now supported. See the README.os390 manpage.

  Changes in existing support

    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.

Modules and Pragmata
  New Modules

    B   Perl compiler and tools. See the B manpage.

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


  Changes in existing modules

    CGI CGI has been updated to version 2.42.

    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.


Utility Changes
    `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.

Documentation Changes
    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.

New Diagnostics
    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 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 "(?{ code })" entry 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 "(?{ code })"
        entry 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 "(?{ code })" entry 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 or
        '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 pairs.

            %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
        perllocale manpage section LOCALE PROBLEMS.


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

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

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


BUGS
    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
    perlbug 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.

SEE ALSO
    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.

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

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

