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PERL56DELTA(1)	       Perl Programmers Reference Guide 	PERL56DELTA(1)

       perl56delta - whats new for perl v5.6.0

       This document describes differences between the 5.005 release and the
       5.6.0 release.

Core Enhancements
       Interpreter cloning, threads, and concurrency

       Perl 5.6.0 introduces the beginnings of support for running multiple
       interpreters concurrently in different threads.	In conjunction with
       the perl_clone() API call, which can be used to selectively duplicate
       the state of any given interpreter, it is possible to compile a piece
       of code once in an interpreter, clone that interpreter one or more
       times, and run all the resulting interpreters in distinct threads.

       On the Windows platform, this feature is used to emulate fork() at the
       interpreter level.  See perlfork for details about that.

       This feature is still in evolution.  It is eventually meant to be used
       to selectively clone a subroutine and data reachable from that subrou
       tine in a separate interpreter and run the cloned subroutine in a sepa
       rate thread.  Since there is no shared data between the interpreters,
       little or no locking will be needed (unless parts of the symbol table
       are explicitly shared).	This is obviously intended to be an easy-to-
       use replacement for the existing threads support.

       Support for cloning interpreters and interpreter concurrency can be
       enabled using the -Dusethreads Configure option (see win32/Makefile for
       how to enable it on Windows.)  The resulting perl executable will be
       functionally identical to one that was built with -Dmultiplicity, but
       the perl_clone() API call will only be available in the former.

       -Dusethreads enables the cpp macro USE_ITHREADS by default, which in
       turn enables Perl source code changes that provide a clear separation
       between the op tree and the data it operates with.  The former is
       immutable, and can therefore be shared between an interpreter and all
       of its clones, while the latter is considered local to each inter
       preter, and is therefore copied for each clone.

       Note that building Perl with the -Dusemultiplicity Configure option is
       adequate if you wish to run multiple independent interpreters concur
       rently in different threads.  -Dusethreads only provides the additional
       functionality of the perl_clone() API call and other support for run
       ning cloned interpreters concurrently.

	   NOTE: This is an experimental feature.  Implementation details are
	   subject to change.

       Lexically scoped warning categories

       You can now control the granularity of warnings emitted by perl at a
       finer level using the "use warnings" pragma.  warnings and perllexwarn
       have copious documentation on this feature.

       Unicode and UTF-8 support

       Perl now uses UTF-8 as its internal representation for character
       strings.  The "utf8" and "bytes" pragmas are used to control this sup
       port in the current lexical scope.  See perlunicode, utf8 and bytes for
       more information.

       This feature is expected to evolve quickly to support some form of I/O
       disciplines that can be used to specify the kind of input and output
       data (bytes or characters).  Until that happens, additional modules
       from CPAN will be needed to complete the toolkit for dealing with Uni

	   NOTE: This should be considered an experimental feature.  Implementation
	   details are subject to change.

       Support for interpolating named characters

       The new "\N" escape interpolates named characters within strings.  For
       example, "Hi! \N{WHITE SMILING FACE}" evaluates to a string with a uni
       code smiley face at the end.

       "our" declarations

       An "our" declaration introduces a value that can be best understood as
       a lexically scoped symbolic alias to a global variable in the package
       that was current where the variable was declared.  This is mostly use
       ful as an alternative to the "vars" pragma, but also provides the
       opportunity to introduce typing and other attributes for such vari
       ables.  See "our" in perlfunc.

       Support for strings represented as a vector of ordinals

       Literals of the form "v1.2.3.4" are now parsed as a string composed of
       characters with the specified ordinals.	This is an alternative, more
       readable way to construct (possibly unicode) strings instead of inter
       polating characters, as in "\x{1}\x{2}\x{3}\x{4}".  The leading "v" may
       be omitted if there are more than two ordinals, so 1.2.3 is parsed the
       same as "v1.2.3".

       Strings written in this form are also useful to represent version "num
       bers".  It is easy to compare such version "numbers" (which are really
       just plain strings) using any of the usual string comparison operators
       "eq", "ne", "lt", "gt", etc., or perform bitwise string operations on
       them using "|", "&", etc.

       In conjunction with the new $^V magic variable (which contains the perl
       version as a string), such literals can be used as a readable way to
       check if youre running a particular version of Perl:

	   # this will parse in older versions of Perl also
	   if ($^V and $^V gt v5.6.0) {
	       # new features supported

       "require" and "use" also have some special magic to support such liter
       als, but this particular usage should be avoided because it leads to
       misleading error messages under versions of Perl which dont support
       vector strings.	Using a true version number will ensure correct behav
       ior in all versions of Perl:

	   require 5.006;    # run time check for v5.6
	   use 5.006_001;    # compile time check for v5.6.1

       Also, "sprintf" and "printf" support the Perl-specific format flag %v
       to print ordinals of characters in arbitrary strings:

	   printf "v%vd", $^V;	       # prints current version, such as "v5.5.650"
	   printf "%*vX", ":", $addr;  # formats IPv6 address
	   printf "%*vb", " ", $bits;  # displays bitstring

       See "Scalar value constructors" in perldata for additional information.

       Improved Perl version numbering system

       Beginning with Perl version 5.6.0, the version number convention has
       been changed to a "dotted integer" scheme that is more commonly found
       in open source projects.

       Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc.
       The next development series following v5.6.0 will be numbered v5.7.x,
       beginning with v5.7.0, and the next major production release following
       v5.6.0 will be v5.8.0.

       The English module now sets $PERL_VERSION to $^V (a string value)
       rather than $] (a numeric value).  (This is a potential incompatibil
       ity.  Send us a report via perlbug if you are affected by this.)

       The v1.2.3 syntax is also now legal in Perl.  See "Support for strings
       represented as a vector of ordinals" for more on that.

       To cope with the new versioning systems use of at least three signifi
       cant digits for each version component, the method used for increment
       ing the subversion number has also changed slightly.  We assume that
       versions older than v5.6.0 have been incrementing the subversion compo
       nent in multiples of 10.  Versions after v5.6.0 will increment them by
       1.  Thus, using the new notation, 5.005_03 is the "same" as v5.5.30,
       and the first maintenance version following v5.6.0 will be v5.6.1
       (which should be read as being equivalent to a floating point value of
       5.006_001 in the older format, stored in $]).

       New syntax for declaring subroutine attributes

       Formerly, if you wanted to mark a subroutine as being a method call or
       as requiring an automatic lock() when it is entered, you had to declare
       that with a "use attrs" pragma in the body of the subroutine.  That can
       now be accomplished with declaration syntax, like this:

	   sub mymethod : locked method;
	   sub mymethod : locked method {

	   sub othermethod :locked :method;
	   sub othermethod :locked :method {

       (Note how only the first ":" is mandatory, and whitespace surrounding
       the ":" is optional.)

       AutoSplit.pm and SelfLoader.pm have been updated to keep the attributes
       with the stubs they provide.  See attributes.

       File and directory handles can be autovivified

       Similar to how constructs such as "$x->[0]" autovivify a reference,
       handle constructors (open(), opendir(), pipe(), socketpair(),
       sysopen(), socket(), and accept()) now autovivify a file or directory
       handle if the handle passed to them is an uninitialized scalar vari
       able.  This allows the constructs such as "open(my $fh, ...)" and
       "open(local $fh,...)"  to be used to create filehandles that will con
       veniently be closed automatically when the scope ends, provided there
       are no other references to them.  This largely eliminates the need for
       typeglobs when opening filehandles that must be passed around, as in
       the following example:

	   sub myopen {
	       open my $fh, "@_"
		    or die "Cant open @_: $!";
	       return $fh;

	       my $f = myopen(";
	       # $f implicitly closed here

       open() with more than two arguments

       If open() is passed three arguments instead of two, the second argument
       is used as the mode and the third argument is taken to be the file
       name.  This is primarily useful for protecting against unintended magic
       behavior of the traditional two-argument form.  See "open" in perlfunc.

       64-bit support

       Any platform that has 64-bit integers either

	       (1) natively as longs or ints
	       (2) via special compiler flags
	       (3) using long long or int64_t

       is able to use "quads" (64-bit integers) as follows:

	  constants (decimal, hexadecimal, octal, binary) in the code

	  arguments to oct() and hex()

	  arguments to print(), printf() and sprintf() (flag prefixes ll, L,

	  printed as such

	  pack() and unpack() "q" and "Q" formats

	  in basic arithmetics: + - * / % (NOTE: operating close to the lim
	   its of the integer values may produce surprising results)

	  in bit arithmetics: & | ^ ~ << >> (NOTE: these used to be forced to
	   be 32 bits wide but now operate on the full native width.)


       Note that unless you have the case (a) you will have to configure and
       compile Perl using the -Duse64bitint Configure flag.

	   NOTE: The Configure flags -Duselonglong and -Duse64bits have been
	   deprecated.	Use -Duse64bitint instead.

       There are actually two modes of 64-bitness: the first one is achieved
       using Configure -Duse64bitint and the second one using Configure
       -Duse64bitall.  The difference is that the first one is minimal and the
       second one maximal.  The first works in more places than the second.

       The "use64bitint" does only as much as is required to get 64-bit inte
       gers into Perl (this may mean, for example, using "long longs") while
       your memory may still be limited to 2 gigabytes (because your pointers
       could still be 32-bit).	Note that the name "64bitint" does not imply
       that your C compiler will be using 64-bit "int"s (it might, but it
       doesnt have to): the "use64bitint" means that you will be able to have
       64 bits wide scalar values.

       The "use64bitall" goes all the way by attempting to switch also inte
       gers (if it can), longs (and pointers) to being 64-bit.	This may cre
       ate an even more binary incompatible Perl than -Duse64bitint: the
       resulting executable may not run at all in a 32-bit box, or you may
       have to reboot/reconfigure/rebuild your operating system to be 64-bit

       Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint
       nor -Duse64bitall.

       Last but not least: note that due to Perls habit of always using
       floating point numbers, the quads are still not true integers.  When
       quads overflow their limits (0...18_446_744_073_709_551_615 unsigned,
       -9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they
       are silently promoted to floating point numbers, after which they will
       start losing precision (in their lower digits).

	   NOTE: 64-bit support is still experimental on most platforms.
	   Existing support only covers the LP64 data model.  In particular, the
	   LLP64 data model is not yet supported.  64-bit libraries and system
	   APIs on many platforms have not stabilized--your mileage may vary.

       Large file support

       If you have filesystems that support "large files" (files larger than 2
       gigabytes), you may now also be able to create and access them from

	   NOTE: The default action is to enable large file support, if
	   available on the platform.

       If the large file support is on, and you have a Fcntl constant O_LARGE
       FILE, the O_LARGEFILE is automatically added to the flags of sysopen().

       Beware that unless your filesystem also supports "sparse files" seeking
       to umpteen petabytes may be inadvisable.

       Note that in addition to requiring a proper file system to do large
       files you may also need to adjust your per-process (or your per-system,
       or per-process-group, or per-user-group) maximum filesize limits before
       running Perl scripts that try to handle large files, especially if you
       intend to write such files.

       Finally, in addition to your process/process group maximum filesize
       limits, you may have quota limits on your filesystems that stop you
       (your user id or your user group id) from using large files.

       Adjusting your process/user/group/file system/operating system limits
       is outside the scope of Perl core language.  For process limits, you
       may try increasing the limits using your shells limits/limit/ulimit
       command before running Perl.  The BSD::Resource extension (not included
       with the standard Perl distribution) may also be of use, it offers the
       getrlimit/setrlimit interface that can be used to adjust process
       resource usage limits, including the maximum filesize limit.

       Long doubles

       In some systems you may be able to use long doubles to enhance the
       range and precision of your double precision floating point numbers
       (that is, Perls numbers).  Use Configure -Duselongdouble to enable
       this support (if it is available).

       "more bits"

       You can "Configure -Dusemorebits" to turn on both the 64-bit support
       and the long double support.

       Enhanced support for sort() subroutines

       Perl subroutines with a prototype of "($$)", and XSUBs in general, can
       now be used as sort subroutines.  In either case, the two elements to
       be compared are passed as normal parameters in @_.  See "sort" in perl

       For unprototyped sort subroutines, the historical behavior of passing
       the elements to be compared as the global variables $a and $b remains

       "sort $coderef @foo" allowed

       sort() did not accept a subroutine reference as the comparison function
       in earlier versions.  This is now permitted.

       File globbing implemented internally

       Perl now uses the File::Glob implementation of the glob() operator
       automatically.  This avoids using an external csh process and the prob
       lems associated with it.

	   NOTE: This is currently an experimental feature.  Interfaces and
	   implementation are subject to change.

       Support for CHECK blocks

       In addition to "BEGIN", "INIT", "END", "DESTROY" and "AUTOLOAD", sub
       routines named "CHECK" are now special.	These are queued up during
       compilation and behave similar to END blocks, except they are called at
       the end of compilation rather than at the end of execution.  They can
       not be called directly.

       POSIX character class syntax [: :] supported

       For example to match alphabetic characters use /[[:alpha:]]/.  See
       perlre for details.

       Better pseudo-random number generator

       In 5.005_0x and earlier, perls rand() function used the C library
       rand(3) function.  As of 5.005_52, Configure tests for drand48(), ran
       dom(), and rand() (in that order) and picks the first one it finds.

       These changes should result in better random numbers from rand().

       Improved "qw//" operator

       The "qw//" operator is now evaluated at compile time into a true list
       instead of being replaced with a run time call to "split()".  This
       removes the confusing misbehaviour of "qw//" in scalar context, which
       had inherited that behaviour from split().


	   $foo = ($bar) = qw(a b c); print "$foo|$bar\n";

       now correctly prints "3|a", instead of "2|a".

       Better worst-case behavior of hashes

       Small changes in the hashing algorithm have been implemented in order
       to improve the distribution of lower order bits in the hashed value.
       This is expected to yield better performance on keys that are repeated

       pack() format Z supported

       The new format type Z is useful for packing and unpacking null-termi
       nated strings.  See "pack" in perlfunc.

       pack() format modifier ! supported

       The new format type modifier ! is useful for packing and unpacking
       native shorts, ints, and longs.	See "pack" in perlfunc.

       pack() and unpack() support counted strings

       The template character / can be used to specify a counted string type
       to be packed or unpacked.  See "pack" in perlfunc.

       Comments in pack() templates

       The # character in a template introduces a comment up to end of the
       line.  This facilitates documentation of pack() templates.

       Weak references

       In previous versions of Perl, you couldnt cache objects so as to allow
       them to be deleted if the last reference from outside the cache is
       deleted.  The reference in the cache would hold a reference count on
       the object and the objects would never be destroyed.

       Another familiar problem is with circular references.  When an object
       references itself, its reference count would never go down to zero, and
       it would not get destroyed until the program is about to exit.

       Weak references solve this by allowing you to "weaken" any reference,
       that is, make it not count towards the reference count.	When the last
       non-weak reference to an object is deleted, the object is destroyed and
       all the weak references to the object are automatically undef-ed.

       To use this feature, you need the Devel::WeakRef package from CPAN,
       which contains additional documentation.

	   NOTE: This is an experimental feature.  Details are subject to change.

       Binary numbers supported

       Binary numbers are now supported as literals, in s?printf formats, and

	   $answer = 0b101010;
	   printf "The answer is: %b\n", oct("0b101010");

       Lvalue subroutines

       Subroutines can now return modifiable lvalues.  See "Lvalue subrou
       tines" in perlsub.

	   NOTE: This is an experimental feature.  Details are subject to change.

       Some arrows may be omitted in calls through references

       Perl now allows the arrow to be omitted in many constructs involving
       subroutine calls through references.  For example, "$foo[10]->(foo)"
       may now be written "$foo[10](foo)".  This is rather similar to how
       the arrow may be omitted from "$foo[10]->{foo}".  Note however, that
       the arrow is still required for "foo(10)->(bar)".

       Boolean assignment operators are legal lvalues

       Constructs such as "($a ||= 2) += 1" are now allowed.

       exists() is supported on subroutine names

       The exists() builtin now works on subroutine names.  A subroutine is
       considered to exist if it has been declared (even if implicitly).  See
       "exists" in perlfunc for examples.

       exists() and delete() are supported on array elements

       The exists() and delete() builtins now work on simple arrays as well.
       The behavior is similar to that on hash elements.

       exists() can be used to check whether an array element has been ini
       tialized.  This avoids autovivifying array elements that dont exist.
       If the array is tied, the EXISTS() method in the corresponding tied
       package will be invoked.

       delete() may be used to remove an element from the array and return it.
       The array element at that position returns to its uninitialized state,
       so that testing for the same element with exists() will return false.
       If the element happens to be the one at the end, the size of the array
       also shrinks up to the highest element that tests true for exists(), or
       0 if none such is found.  If the array is tied, the DELETE() method in
       the corresponding tied package will be invoked.

       See "exists" in perlfunc and "delete" in perlfunc for examples.

       Pseudo-hashes work better

       Dereferencing some types of reference values in a pseudo-hash, such as
       "$ph->{foo}[1]", was accidentally disallowed.  This has been corrected.

       When applied to a pseudo-hash element, exists() now reports whether the
       specified value exists, not merely if the key is valid.

       delete() now works on pseudo-hashes.  When given a pseudo-hash element
       or slice it deletes the values corresponding to the keys (but not the
       keys themselves).  See "Pseudo-hashes: Using an array as a hash" in

       Pseudo-hash slices with constant keys are now optimized to array
       lookups at compile-time.

       List assignments to pseudo-hash slices are now supported.

       The "fields" pragma now provides ways to create pseudo-hashes, via
       fields::new() and fields::phash().  See fields.

	   NOTE: The pseudo-hash data type continues to be experimental.
	   Limiting oneself to the interface elements provided by the
	   fields pragma will provide protection from any future changes.

       Automatic flushing of output buffers

       fork(), exec(), system(), qx//, and pipe open()s now flush buffers of
       all files opened for output when the operation was attempted.  This
       mostly eliminates confusing buffering mishaps suffered by users unaware
       of how Perl internally handles I/O.

       This is not supported on some platforms like Solaris where a suitably
       correct implementation of fflush(NULL) isnt available.

       Better diagnostics on meaningless filehandle operations

       Constructs such as "open()" and "close()" are compile time
       errors.	Attempting to read from filehandles that were opened only for
       writing will now produce warnings (just as writing to read-only file
       handles does).

       Where possible, buffered data discarded from duped input filehandle

       "open(NEW, "<&OLD")" now attempts to discard any data that was previ
       ously read and buffered in "OLD" before duping the handle.  On plat
       forms where doing this is allowed, the next read operation on "NEW"
       will return the same data as the corresponding operation on "OLD".
       Formerly, it would have returned the data from the start of the follow
       ing disk block instead.

       eof() has the same old magic as <>

       "eof()" would return true if no attempt to read from "<>" had yet been
       made.  "eof()" has been changed to have a little magic of its own, it
       now opens the "<>" files.

       binmode() can be used to set :crlf and :raw modes

       binmode() now accepts a second argument that specifies a discipline for
       the handle in question.	The two pseudo-disciplines ":raw" and ":crlf"
       are currently supported on DOS-derivative platforms.  See "binmode" in
       perlfunc and open.

       "-T" filetest recognizes UTF-8 encoded files as "text"

       The algorithm used for the "-T" filetest has been enhanced to correctly
       identify UTF-8 content as "text".

       system(), backticks and pipe open now reflect exec() failure

       On Unix and similar platforms, system(), qx() and open(FOO, "cmd |")
       etc., are implemented via fork() and exec().  When the underlying
       exec() fails, earlier versions did not report the error properly, since
       the exec() happened to be in a different process.

       The child process now communicates with the parent about the error in
       launching the external command, which allows these constructs to return
       with their usual error value and set $!.

       Improved diagnostics

       Line numbers are no longer suppressed (under most likely circumstances)
       during the global destruction phase.

       Diagnostics emitted from code running in threads other than the main
       thread are now accompanied by the thread ID.

       Embedded null characters in diagnostics now actually show up.  They
       used to truncate the message in prior versions.

       $foo::a and $foo::b are now exempt from "possible typo" warnings only
       if sort() is encountered in package "foo".

       Unrecognized alphabetic escapes encountered when parsing quote con
       structs now generate a warning, since they may take on new semantics in
       later versions of Perl.

       Many diagnostics now report the internal operation in which the warning
       was provoked, like so:

	   Use of uninitialized value in concatenation (.) at (eval 1) line 1.
	   Use of uninitialized value in print at (eval 1) line 1.

       Diagnostics  that occur within eval may also report the file and line
       number where the eval is located, in addition to the eval sequence num
       ber and the line number within the evaluated text itself.  For example:

	   Not enough arguments for scalar at (eval 4)[newlib/perl5db.pl:1411] line 2, at EOF

       Diagnostics follow STDERR

       Diagnostic output now goes to whichever file the "STDERR" handle is
       pointing at, instead of always going to the underlying C runtime
       librarys "stderr".

       More consistent close-on-exec behavior

       On systems that support a close-on-exec flag on filehandles, the flag
       is now set for any handles created by pipe(), socketpair(), socket(),
       and accept(), if that is warranted by the value of $^F that may be in
       effect.	Earlier versions neglected to set the flag for handles created
       with these operators.  See "pipe" in perlfunc, "socketpair" in perl
       func, "socket" in perlfunc, "accept" in perlfunc, and "$^F" in perlvar.

       syswrite() ease-of-use

       The length argument of "syswrite()" has become optional.

       Better syntax checks on parenthesized unary operators

       Expressions such as:

	   print defined(&foo,&bar,&baz);
	   print uc("foo","bar","baz");

       used to be accidentally allowed in earlier versions, and produced
       unpredictable behaviour.  Some produced ancillary warnings when used in
       this way; others silently did the wrong thing.

       The parenthesized forms of most unary operators that expect a single
       argument now ensure that they are not called with more than one argu
       ment, making the cases shown above syntax errors.  The usual behaviour

	   print defined &foo, &bar, &baz;
	   print uc "foo", "bar", "baz";
	   undef $foo, &bar;

       remains unchanged.  See perlop.

       Bit operators support full native integer width

       The bit operators (& | ^ ~ << >>) now operate on the full native inte
       gral width (the exact size of which is available in $Config{ivsize}).
       For example, if your platform is either natively 64-bit or if Perl has
       been configured to use 64-bit integers, these operations apply to 8
       bytes (as opposed to 4 bytes on 32-bit platforms).  For portability, be
       sure to mask off the excess bits in the result of unary "~", e.g., "~$x
       & 0xffffffff".

       Improved security features

       More potentially unsafe operations taint their results for improved

       The "passwd" and "shell" fields returned by the getpwent(), getpwnam(),
       and getpwuid() are now tainted, because the user can affect their own
       encrypted password and login shell.

       The variable modified by shmread(), and messages returned by msgrcv()
       (and its object-oriented interface IPC::SysV::Msg::rcv) are also
       tainted, because other untrusted processes can modify messages and
       shared memory segments for their own nefarious purposes.

       More functional bareword prototype (*)

       Bareword prototypes have been rationalized to enable them to be used to
       override builtins that accept barewords and interpret them in a special
       way, such as "require" or "do".

       Arguments prototyped as "*" will now be visible within the subroutine
       as either a simple scalar or as a reference to a typeglob.  See "Proto
       types" in perlsub.

       "require" and "do" may be overridden

       "require" and "do file" operations may be overridden locally by
       importing subroutines of the same name into the current package (or
       globally by importing them into the CORE::GLOBAL:: namespace).  Over
       riding "require" will also affect "use", provided the override is visi
       ble at compile-time.  See "Overriding Built-in Functions" in perlsub.

       $^X variables may now have names longer than one character

       Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax
       error.  Now variable names that begin with a control character may be
       arbitrarily long.  However, for compatibility reasons, these variables
       must be written with explicit braces, as "${^XY}" for example.
       "${^XYZ}" is synonymous with ${"\cXYZ"}.  Variable names with more than
       one control character, such as "${^XY^Z}", are illegal.

       The old syntax has not changed.	As before, ^X may be either a lit
       eral control-X character or the two-character sequence caret plus
       X.  When braces are omitted, the variable name stops after the con
       trol character.	Thus "$^XYZ" continues to be synonymous with "$^X .
       "YZ"" as before.

       As before, lexical variables may not have names beginning with control
       characters.  As before, variables whose names begin with a control
       character are always forced to be in package main.  All such vari
       ables are reserved for future extensions, except those that begin with
       "^_", which may be used by user programs and are guaranteed not to
       acquire special meaning in any future version of Perl.

       New variable $^C reflects "-c" switch

       $^C has a boolean value that reflects whether perl is being run in com
       pile-only mode (i.e. via the "-c" switch).  Since BEGIN blocks are exe
       cuted under such conditions, this variable enables perl code to deter
       mine whether actions that make sense only during normal running are
       warranted.  See perlvar.

       New variable $^V contains Perl version as a string

       $^V contains the Perl version number as a string composed of characters
       whose ordinals match the version numbers, i.e. v5.6.0.  This may be
       used in string comparisons.

       See "Support for strings represented as a vector of ordinals" for an

       Optional Y2K warnings

       If Perl is built with the cpp macro "PERL_Y2KWARN" defined, it emits
       optional warnings when concatenating the number 19 with another number.

       This behavior must be specifically enabled when running Configure.  See
       INSTALL and README.Y2K.

       Arrays now always interpolate into double-quoted strings

       In double-quoted strings, arrays now interpolate, no matter what.  The
       behavior in earlier versions of perl 5 was that arrays would interpo
       late 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\@exam
       ple.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 downgraded 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 dont backslash the "@".  See
       http://www.plover.com/~mjd/perl/at-error.html for more details about
       the history here.

       @- and @+ provide starting/ending offsets of regex matches

       The new magic variables @- and @+ provide the starting and ending off
       sets, respectively, of $&, $1, $2, etc.	See perlvar for details.

Modules and Pragmata

	   While used internally by Perl as a pragma, this module also pro
	   vides a way to fetch subroutine and variable attributes.  See

       B   The Perl Compiler suite has been extensively reworked for this
	   release.  More of the standard Perl testsuite passes when run under
	   the Compiler, but there is still a significant way to go to achieve
	   production quality compiled executables.

	       NOTE: The Compiler suite remains highly experimental.  The
	       generated code may not be correct, even when it manages to execute
	       without errors.

	   Overall, Benchmark results exhibit lower average error and better
	   timing accuracy.

	   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 code
	   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)".

	   timethese() now returns a reference to a hash of Benchmark objects
	   containing the test results, keyed on the names of the tests.

	   timethis() now returns the iterations field in the Benchmark result
	   object instead of 0.

	   timethese(), timethis(), and the new cmpthese() (see below) can
	   also take a format specifier of none to suppress output.

	   A new function countit() is just like timeit() except that it takes
	   a TIME instead of a COUNT.

	   A new function cmpthese() prints a chart comparing the results of
	   each test returned from a timethese() call.	For each possible pair
	   of tests, the percentage speed difference (iters/sec or sec
	   onds/iter) is shown.

	   For other details, see Benchmark.

	   The ByteLoader is a dedicated extension to generate and run Perl
	   bytecode.  See ByteLoader.

	   References can now be used.

	   The new version also allows a leading underscore in constant names,
	   but disallows a double leading underscore (as in "__LINE__").  Some
	   other names are disallowed or warned against, including BEGIN, END,
	   etc.  Some names which were forced into main:: used to fail
	   silently in some cases; now theyre fatal (outside of main::) and
	   an optional warning (inside of main::).  The ability to detect
	   whether a constant had been set with a given name has been added.

	   See constant.

	   This pragma implements the "\N" string escape.  See charnames.

	   A "Maxdepth" setting can be specified to avoid venturing too deeply
	   into deep data structures.  See Data::Dumper.

	   The XSUB implementation of Dump() is now automatically called if
	   the "Useqq" setting is not in use.

	   Dumping "qr//" objects works correctly.

       DB  "DB" is an experimental module that exposes a clean abstraction to
	   Perls debugging API.

	   DB_File can now be built with Berkeley DB versions 1, 2 or 3.  See

	   Devel::DProf, a Perl source code profiler has been added.  See
	   Devel::DProf and dprofpp.

	   The Devel::Peek module provides access to the internal representa
	   tion of Perl variables and data.  It is a data debugging tool for
	   the XS programmer.

	   The Dumpvalue module provides screen dumps of Perl data.

	   DynaLoader now supports a dl_unload_file() function on platforms
	   that support unloading shared objects using dlclose().

	   Perl can also optionally arrange to unload all extension shared
	   objects loaded by Perl.  To enable this, build Perl with the Con
	   figure option "-Accflags=-DDL_UNLOAD_ALL_AT_EXIT".  (This maybe
	   useful if you are using Apache with mod_perl.)

	   $PERL_VERSION now stands for $^V (a string value) rather than for
	   $] (a numeric value).

       Env Env now supports accessing environment variables like PATH as array

	   More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
	   large file (more than 4GB) access (NOTE: the O_LARGEFILE is auto
	   matically added to sysopen() flags if large file support has been
	   configured, as is the default), Free/Net/OpenBSD locking behaviour
	   flags F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined
	   mask of O_RDONLY, O_WRONLY, and O_RDWR.  The seek()/sysseek() con
	   stants SEEK_SET, SEEK_CUR, and SEEK_END are available via the
	   ":seek" tag.  The chmod()/stat() S_IF* constants and S_IS* func
	   tions are available via the ":mode" tag.

	   A compare_text() function has been added, which allows custom com
	   parison functions.  See File::Compare.

	   File::Find now works correctly when the wanted() function is either
	   autoloaded or is a symbolic reference.

	   A bug that caused File::Find to lose track of the working directory
	   when pruning top-level directories has been fixed.

	   File::Find now also supports several other options to control its
	   behavior.  It can follow symbolic links if the "follow" option is
	   specified.  Enabling the "no_chdir" option will make File::Find
	   skip changing the current directory when walking directories.  The
	   "untaint" flag can be useful when running with taint checks

	   See File::Find.

	   This extension implements BSD-style file globbing.  By default, it
	   will also be used for the internal implementation of the glob()
	   operator.  See File::Glob.

	   New methods have been added to the File::Spec module: devnull()
	   returns the name of the null device (/dev/null on Unix) and
	   tmpdir() the name of the temp directory (normally /tmp on Unix).
	   There are now also methods to convert between absolute and relative
	   filenames: abs2rel() and rel2abs().	For compatibility with operat
	   ing systems that specify volume names in file paths, the split
	   path(), splitdir(), and catdir() methods have been added.

	   The new File::Spec::Functions modules provides a function interface
	   to the File::Spec module.  Allows shorthand

	       $fullname = catfile($dir1, $dir2, $file);

	   instead of

	       $fullname = File::Spec->catfile($dir1, $dir2, $file);

	   Getopt::Long licensing has changed to allow the Perl Artistic
	   License as well as the GPL. It used to be GPL only, which got in
	   the way of non-GPL applications that wanted to use Getopt::Long.

	   Getopt::Long encourages the use of Pod::Usage to produce help mes
	   sages. For example:

	       use Getopt::Long;
	       use Pod::Usage;
	       my $man = 0;
	       my $help = 0;
	       GetOptions(help|? => \$help, man => \$man) or pod2usage(2);
	       pod2usage(1) if $help;
	       pod2usage(-exitstatus => 0, -verbose => 2) if $man;


	       =head1 NAME

	       sample - Using Getopt::Long and Pod::Usage

	       =head1 SYNOPSIS

	       sample [options] [file ...]

		  -help 	   brief help message
		  -man		   full documentation

	       =head1 OPTIONS

	       =over 8

	       =item B<-help>

	       Print a brief help message and exits.

	       =item B<-man>

	       Prints the manual page and exits.


	       =head1 DESCRIPTION

	       B will read the given input file(s) and do something
	       useful with the contents thereof.


	   See Pod::Usage for details.

	   A bug that prevented the non-option call-back <> from being speci
	   fied as the first argument has been fixed.

	   To specify the characters < and > as option starters, use ><. Note,
	   however, that changing option starters is strongly deprecated.

       IO  write() and syswrite() will now accept a single-argument form of
	   the call, for consistency with Perls syswrite().

	   You can now create a TCP-based IO::Socket::INET without forcing a
	   connect attempt.  This allows you to configure its options (like
	   making it non-blocking) and then call connect() manually.

	   A bug that prevented the IO::Socket::protocol() accessor from ever
	   returning the correct value has been corrected.

	   IO::Socket::connect now uses non-blocking IO instead of alarm() to
	   do connect timeouts.

	   IO::Socket::accept now uses select() instead of alarm() for doing

	   IO::Socket::INET->new now sets $! correctly on failure. $@ is still
	   set for backwards compatibility.

       JPL Java Perl Lingo is now distributed with Perl.  See jpl/README for
	   more information.

       lib "use lib" now weeds out any trailing duplicate entries.  "no lib"
	   removes all named entries.

	   The bitwise operations "<<", ">>", "&", "|", and "~" are now sup
	   ported on bigints.

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

	   The class method "display_format" and the corresponding object
	   method "display_format", in addition to accepting just one argu
	   ment, now can also accept a parameter hash.	Recognized keys of a
	   parameter hash are "style", which corresponds to the old one param
	   eter case, and two new parameters: "format", which is a
	   printf()-style format string (defaults usually to "%.15g", you can
	   revert to the default by setting the format string to "undef") used
	   for both parts of a complex number, and "polar_pretty_print"
	   (defaults to true), which controls whether an attempt is made to
	   try to recognize small multiples and rationals of pi (2pi, pi/2) at
	   the argument (angle) of a polar complex number.

	   The potentially disruptive change is that in list context both
	   methods now return the parameter hash, instead of only the value of
	   the "style" parameter.

	   A little bit of radial trigonometry (cylindrical and spherical),
	   radial coordinate conversions, and the great circle distance were

       Pod::Parser, Pod::InputObjects
	   Pod::Parser is a base class for parsing and selecting sections of
	   pod documentation from an input stream.  This module takes care of
	   identifying pod paragraphs and commands in the input and hands off
	   the parsed paragraphs and commands to user-defined methods which
	   are free to interpret or translate them as they see fit.

	   Pod::InputObjects defines some input objects needed by Pod::Parser,
	   and for advanced users of Pod::Parser that need more about a com
	   mand besides its name and text.

	   As of release 5.6.0 of Perl, Pod::Parser is now the officially
	   sanctioned "base parser code" recommended for use by all pod2xxx
	   translators.  Pod::Text (pod2text) and Pod::Man (pod2man) have
	   already been converted to use Pod::Parser and efforts to convert
	   Pod::HTML (pod2html) are already underway.  For any questions or
	   comments about pod parsing and translating issues and utilities,
	   please use the pod-people@perl.org mailing list.

	   For further information, please see Pod::Parser and Pod::InputOb

       Pod::Checker, podchecker
	   This utility checks pod files for correct syntax, according to
	   perlpod.  Obvious errors are flagged as such, while warnings are
	   printed for mistakes that can be handled gracefully.  The checklist
	   is not complete yet.  See Pod::Checker.

       Pod::ParseUtils, Pod::Find
	   These modules provide a set of gizmos that are useful mainly for
	   pod translators.  Pod::Find traverses directory structures and
	   returns found pod files, along with their canonical names (like
	   "File::Spec::Unix").  Pod::ParseUtils contains Pod::List (useful
	   for storing pod list information), Pod::Hyperlink (for parsing the
	   contents of "L<>" sequences) and Pod::Cache (for caching informa
	   tion about pod files, e.g., link nodes).

       Pod::Select, podselect
	   Pod::Select is a subclass of Pod::Parser which provides a function
	   named "podselect()" to filter out user-specified sections of raw
	   pod documentation from an input stream. podselect is a script that
	   provides access to Pod::Select from other scripts to be used as a
	   filter.  See Pod::Select.

       Pod::Usage, pod2usage
	   Pod::Usage provides the function "pod2usage()" to print usage mes
	   sages for a Perl script based on its embedded pod documentation.
	   The pod2usage() function is generally useful to all script authors
	   since it lets them write and maintain a single source (the pods)
	   for documentation, thus removing the need to create and maintain
	   redundant usage message text consisting of information already in
	   the pods.

	   There is also a pod2usage script which can be used from other kinds
	   of scripts to print usage messages from pods (even for non-Perl
	   scripts with pods embedded in comments).

	   For details and examples, please see Pod::Usage.

       Pod::Text and Pod::Man
	   Pod::Text has been rewritten to use Pod::Parser.  While pod2text()
	   is still available for backwards compatibility, the module now has
	   a new preferred interface.  See Pod::Text for the details.  The new
	   Pod::Text module is easily subclassed for tweaks to the output, and
	   two such subclasses (Pod::Text::Termcap for man-page-style bold and
	   underlining using termcap information, and Pod::Text::Color for
	   markup with ANSI color sequences) are now standard.

	   pod2man has been turned into a module, Pod::Man, which also uses
	   Pod::Parser.  In the process, several outstanding bugs related to
	   quotes in section headers, quoting of code escapes, and nested
	   lists have been fixed.  pod2man is now a wrapper script around this

	   An EXISTS method has been added to this module (and sdbm_exists()
	   has been added to the underlying sdbm library), so one can now call
	   exists on an SDBM_File tied hash and get the correct result, rather
	   than a runtime error.

	   A bug that may have caused data loss when more than one disk block
	   happens to be read from the database in a single FETCH() has been

	   Sys::Syslog now uses XSUBs to access facilities from syslog.h so it
	   no longer requires syslog.ph to exist.

	   Sys::Hostname now uses XSUBs to call the C librarys gethostname()
	   or uname() if they exist.

	   Term::ANSIColor is a very simple module to provide easy and read
	   able access to the ANSI color and highlighting escape sequences,
	   supported by most ANSI terminal emulators.  It is now included

	   The timelocal() and timegm() functions used to silently return
	   bogus results when the date fell outside the machines integer
	   range.  They now consistently croak() if the date falls in an
	   unsupported range.

	   The error return value in list context has been changed for all
	   functions that return a list of values.  Previously these functions
	   returned a list with a single element "undef" if an error occurred.
	   Now these functions return the empty list in these situations.
	   This applies to the following functions:


	   The remaining functions are unchanged and continue to return
	   "undef" on error even in list context.

	   The Win32::SetLastError(ERROR) function has been added as a comple
	   ment to the Win32::GetLastError() function.

	   The new Win32::GetFullPathName(FILENAME) returns the full absolute
	   pathname for FILENAME in scalar context.  In list context it
	   returns a two-element list containing the fully qualified directory
	   name and the filename.  See Win32.

	   The XSLoader extension is a simpler alternative to DynaLoader.  See

       DBM Filters
	   A new feature called "DBM Filters" has been added to all the DBM
	   modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
	   DBM Filters add four new methods to each DBM module:


	   These can be used to filter key-value pairs before the pairs are
	   written to the database or just after they are read from the
	   database.  See perldbmfilter for further information.


       "use attrs" is now obsolete, and is only provided for backward-compati
       bility.	Its been replaced by the "sub : attributes" syntax.  See
       "Subroutine Attributes" in perlsub and attributes.

       Lexical warnings pragma, "use warnings;", to control optional warnings.
       See perllexwarn.

       "use filetest" to control the behaviour of filetests ("-r" "-w" ...).
       Currently only one subpragma implemented, "use filetest access;",
       that uses access(2) or equivalent to check permissions instead of using
       stat(2) as usual.  This matters in filesystems where there are ACLs
       (access control lists): the stat(2) might lie, but access(2) knows bet

       The "open" pragma can be used to specify default disciplines for handle
       constructors (e.g. open()) and for qx//.  The two pseudo-disciplines
       ":raw" and ":crlf" are currently supported on DOS-derivative platforms
       (i.e. where binmode is not a no-op).  See also "binmode() can be used
       to set :crlf and :raw modes".

Utility Changes

       "dprofpp" is used to display profile data generated using
       "Devel::DProf".	See dprofpp.


       The "find2perl" utility now uses the enhanced features of the
       File::Find module.  The -depth and -follow options are supported.  Pod
       documentation is also included in the script.


       The "h2xs" tool can now work in conjunction with "C::Scan" (available
       from CPAN) to automatically parse real-life header files.  The "-M",
       "-a", "-k", and "-o" options are new.


       "perlcc" now supports the C and Bytecode backends.  By default, it gen
       erates output from the simple C backend rather than the optimized C

       Support for non-Unix platforms has been improved.


       "perldoc" has been reworked to avoid possible security holes.  It will
       not by default let itself be run as the superuser, but you may still
       use the -U switch to try to make it drop privileges first.

       The Perl Debugger

       Many bug fixes and enhancements were added to perl5db.pl, the Perl
       debugger.  The help documentation was rearranged.  New commands include
       "< ?", "> ?", and "{ ?" to list out current actions, "man docpage" to
       run your doc viewer on some perl docset, and support for quoted
       options.  The help information was rearranged, and should be viewable
       once again if youre using less as your pager.  A serious security hole
       was plugged--you should immediately remove all older versions of the
       Perl debugger as installed in previous releases, all the way back to
       perl3, from your system to avoid being bitten by this.

Improved Documentation
       Many of the platform-specific README files are now part of the perl
       installation.  See perl for the complete list.

	   The official list of public Perl API functions.

	   A tutorial for beginners on object-oriented Perl.

	   An introduction to using the Perl Compiler suite.

	   A howto document on using the DBM filter facility.

	   All material unrelated to running the Perl debugger, plus all low-
	   level guts-like details that risked crushing the casual user of the
	   debugger, have been relocated from the old manpage to the next
	   entry below.

	   This new manpage contains excessively low-level material not
	   related to the Perl debugger, but slightly related to debugging
	   Perl itself.  It also contains some arcane internal details of how
	   the debugging process works that may only be of interest to devel
	   opers of Perl debuggers.

	   Notes on the fork() emulation currently available for the Windows

	   An introduction to writing Perl source filters.

	   Some guidelines for hacking the Perl source code.

	   A list of internal functions in the Perl source code.  (List is
	   currently empty.)

	   Introduction and reference information about lexically scoped warn
	   ing categories.

	   Detailed information about numbers as they are represented in Perl.

	   A tutorial on using open() effectively.

	   A tutorial that introduces the essentials of references.

	   A tutorial on managing class data for object modules.

	   Discussion of the most often wanted features that may someday be
	   supported in Perl.

	   An introduction to Unicode support features in Perl.

Performance enhancements
       Simple sort() using { $a <=> $b } and the like are optimized

       Many common sort() operations using a simple inlined block are now
       optimized for faster performance.

       Optimized assignments to lexical variables

       Certain operations in the RHS of assignment statements have been opti
       mized to directly set the lexical variable on the LHS, eliminating
       redundant copying overheads.

       Faster subroutine calls

       Minor changes in how subroutine calls are handled internally provide
       marginal improvements in performance.

       delete(), each(), values() and hash iteration are faster

       The hash values returned by delete(), each(), values() and hashes in a
       list context are the actual values in the hash, instead of copies.
       This results in significantly better performance, because it eliminates
       needless copying in most situations.

Installation and Configuration Improvements
       -Dusethreads means something different

       The -Dusethreads flag now enables the experimental interpreter-based
       thread support by default.  To get the flavor of experimental threads
       that was in 5.005 instead, you need to run Configure with "-Dusethreads

       As of v5.6.0, interpreter-threads support is still lacking a way to
       create new threads from Perl (i.e., "use Thread;" will not work with
       interpreter threads).  "use Thread;" continues to be available when you
       specify the -Duse5005threads option to Configure, bugs and all.

	   NOTE: Support for threads continues to be an experimental feature.
	   Interfaces and implementation are subject to sudden and drastic changes.

       New Configure flags

       The following new flags may be enabled on the Configure command line by
       running Configure with "-Dflag".

	   usethreads useithreads      (new interpreter threads: no Perl API yet)
	   usethreads use5005threads   (threads as they were in 5.005)

	   use64bitint		       (equal to now deprecated use64bits)

	   usesocks		       (only SOCKS v5 supported)

       Threadedness and 64-bitness now more daring

       The Configure options enabling the use of threads and the use of
       64-bitness are now more daring in the sense that they no more have an
       explicit list of operating systems of known threads/64-bit capabili
       ties.  In other words: if your operating system has the necessary APIs
       and datatypes, you should be able just to go ahead and use them, for
       threads by Configure -Dusethreads, and for 64 bits either explicitly by
       Configure -Duse64bitint or implicitly if your system has 64-bit wide
       datatypes.  See also "64-bit support".

       Long Doubles

       Some platforms have "long doubles", floating point numbers of even
       larger range than ordinary "doubles".  To enable using long doubles for
       Perls scalars, use -Duselongdouble.


       You can enable both -Duse64bitint and -Duselongdouble with -Duse
       morebits.  See also "64-bit support".


       Some platforms support system APIs that are capable of handling large
       files (typically, files larger than two gigabytes).  Perl will try to
       use these APIs if you ask for -Duselargefiles.

       See "Large file support" for more information.


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

       SOCKS support

       You can use "Configure -Dusesocks" which causes Perl to probe for the
       SOCKS proxy protocol library (v5, not v4).  For more information on
       SOCKS, see:


       "-A" flag

       You can "post-edit" the Configure variables using the Configure "-A"
       switch.	The editing happens immediately after the platform specific
       hints files have been processed but before the actual configuration
       process starts.	Run "Configure -h" to find out the full "-A" syntax.

       Enhanced Installation Directories

       The installation structure has been enriched to improve the support for
       maintaining multiple versions of perl, to provide locations for vendor-
       supplied modules, scripts, and manpages, and to ease maintenance of
       locally-added modules, scripts, and manpages.  See the section on
       Installation Directories in the INSTALL file for complete details.  For
       most users building and installing from source, the defaults should be

       If you previously used "Configure -Dsitelib" or "-Dsitearch" to set
       special values for library directories, you might wish to consider
       using the new "-Dsiteprefix" setting instead.  Also, if you wish to re-
       use a config.sh file from an earlier version of perl, you should be
       sure to check that Configure makes sensible choices for the new direc
       tories.	See INSTALL for complete details.

Platform specific changes
       Supported platforms

	  The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the
	   Thread extension.

	  GNU/Hurd is now supported.

	  Rhapsody/Darwin is now supported.

	  EPOC is now supported (on Psion 5).

	  The cygwin port (formerly cygwin32) has been greatly improved.


	  Perl now works with djgpp 2.02 (and 2.03 alpha).

	  Environment variable names are not converted to uppercase any more.

	  Incorrect exit codes from backticks have been fixed.

	  This port continues to use its own builtin globbing (not

       OS390 (OpenEdition MVS)

       Support for this EBCDIC platform has not been renewed in this release.
       There are difficulties in reconciling Perls standardization on UTF-8
       as its internal representation for characters with the EBCDIC character
       set, because the two are incompatible.

       It is unclear whether future versions will renew support for this plat
       form, but the possibility exists.


       Numerous revisions and extensions to configuration, build, testing, and
       installation process to accommodate core changes and VMS-specific

       Expand %ENV-handling code to allow runtime mapping to logical names,
       CLI symbols, and CRTL environ array.

       Extension of subprocess invocation code to accept filespecs as command

       Add to Perl command line processing the ability to use default file
       types and to recognize Unix-style "2>&1".

       Expansion of File::Spec::VMS routines, and integration into ExtU

       Extension of ExtUtils::MM_VMS to handle complex extensions more flexi

       Barewords at start of Unix-syntax paths may be treated as text rather
       than only as logical names.

       Optional secure translation of several logical names used internally by

       Miscellaneous bugfixing and porting of new core code to VMS.

       Thanks are gladly extended to the many people who have contributed VMS
       patches, testing, and ideas.


       Perl can now emulate fork() internally, using multiple interpreters
       running in different concurrent threads.  This support must be enabled
       at build time.  See perlfork for detailed information.

       When given a pathname that consists only of a drivename, such as "A:",
       opendir() and stat() now use the current working directory for the
       drive rather than the drive root.

       The builtin XSUB functions in the Win32:: namespace are documented.
       See Win32.

       $^X now contains the full path name of the running executable.

       A Win32::GetLongPathName() function is provided to complement
       Win32::GetFullPathName() and Win32::GetShortPathName().	See Win32.

       POSIX::uname() is supported.

       system(1,...) now returns true process IDs rather than process handles.
       kill() accepts any real process id, rather than strictly return values
       from system(1,...).

       For better compatibility with Unix, "kill(0, $pid)" can now be used to
       test whether a process exists.

       The "Shell" module is supported.

       Better support for building Perl under command.com in Windows 95 has
       been added.

       Scripts are read in binary mode by default to allow ByteLoader (and the
       filter mechanism in general) to work properly.  For compatibility, the
       DATA filehandle will be set to text mode if a carriage return is
       detected at the end of the line containing the __END__ or __DATA__
       token; if not, the DATA filehandle will be left open in binary mode.
       Earlier versions always opened the DATA filehandle in text mode.

       The glob() operator is implemented via the "File::Glob" extension,
       which supports glob syntax of the C shell.  This increases the flexi
       bility of the glob() operator, but there may be compatibility issues
       for programs that relied on the older globbing syntax.  If you want to
       preserve compatibility with the older syntax, you might want to run
       perl with "-MFile::DosGlob".  For details and compatibility informa
       tion, see File::Glob.

Significant bug fixes
        on empty files

       With $/ set to "undef", "slurping" an empty file returns a string of
       zero length (instead of "undef", as it used to) the first time the HAN
       DLE is read after $/ is set to "undef".	Further reads yield "undef".

       This means that the following will append "foo" to an empty file (it
       used to do nothing):

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

       The behaviour of:

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

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

       "eval ..." improvements

       Line numbers (as reflected by caller() and most diagnostics) within
       "eval ..." were often incorrect where here documents were involved.
       This has been corrected.

       Lexical lookups for variables appearing in "eval ..." within
       functions that were themselves called within an "eval ..." were
       searching the wrong place for lexicals.	The lexical search now cor
       rectly ends at the subroutines block boundary.

       The use of "return" within "eval {...}" caused $@ not to be reset cor
       rectly when no exception occurred within the eval.  This has been

       Parsing of here documents used to be flawed when they appeared as the
       replacement expression in "eval s/.../.../e".  This has been fixed.

       All compilation errors are true errors

       Some "errors" encountered at compile time were by necessity generated
       as warnings followed by eventual termination of the program.  This
       enabled more such errors to be reported in a single run, rather than
       causing a hard stop at the first error that was encountered.

       The mechanism for reporting such errors has been reimplemented to queue
       compile-time errors and report them at the end of the compilation as
       true errors rather than as warnings.  This fixes cases where error mes
       sages leaked through in the form of warnings when code was compiled at
       run time using "eval STRING", and also allows such errors to be reli
       ably trapped using "eval "..."".

       Implicitly closed filehandles are safer

       Sometimes implicitly closed filehandles (as when they are localized,
       and Perl automatically closes them on exiting the scope) could inadver
       tently set $? or $!.  This has been corrected.

       Behavior of list slices is more consistent

       When taking a slice of a literal list (as opposed to a slice of an
       array or hash), Perl used to return an empty list if the result hap
       pened to be composed of all undef values.

       The new behavior is to produce an empty list if (and only if) the orig
       inal list was empty.  Consider the following example:

	   @a = (1,undef,undef,2)[2,1,2];

       The old behavior would have resulted in @a having no elements.  The new
       behavior ensures it has three undefined elements.

       Note in particular that the behavior of slices of the following cases
       remains unchanged:

	   @a = ()[1,2];
	   @a = (getpwent)[7,0];
	   @a = (anything_returning_empty_list())[2,1,2];
	   @a = @b[2,1,2];
	   @a = @c{a,b,c};

       See perldata.

       "(\$)" prototype and $foo{a}

       A scalar reference prototype now correctly allows a hash or array ele
       ment in that slot.

       "goto &sub" and AUTOLOAD

       The "goto &sub" construct works correctly when &sub happens to be

       "-bareword" allowed under "use integer"

       The autoquoting of barewords preceded by "-" did not work in prior
       versions when the "integer" pragma was enabled.	This has been fixed.

       Failures in DESTROY()

       When code in a destructor threw an exception, it went unnoticed in ear
       lier versions of Perl, unless someone happened to be looking in $@ just
       after the point the destructor happened to run.	Such failures are now
       visible as warnings when warnings are enabled.

       Locale bugs fixed

       printf() and sprintf() previously reset the numeric locale back to the
       default "C" locale.  This has been fixed.

       Numbers formatted according to the local numeric locale (such as using
       a decimal comma instead of a decimal dot) caused "isnt numeric" warn
       ings, even while the operations accessing those numbers produced cor
       rect results.  These warnings have been discontinued.

       Memory leaks

       The "eval return sub {...}" construct could sometimes leak memory.
       This has been fixed.

       Operations that arent filehandle constructors used to leak memory when
       used on invalid filehandles.  This has been fixed.

       Constructs that modified @_ could fail to deallocate values in @_ and
       thus leak memory.  This has been corrected.

       Spurious subroutine stubs after failed subroutine calls

       Perl could sometimes create empty subroutine stubs when a subroutine
       was not found in the package.  Such cases stopped later method lookups
       from progressing into base packages.  This has been corrected.

       Taint failures under "-U"

       When running in unsafe mode, taint violations could sometimes cause
       silent failures.  This has been fixed.

       END blocks and the "-c" switch

       Prior versions used to run BEGIN and END blocks when Perl was run in
       compile-only mode.  Since this is typically not the expected behavior,
       END blocks are not executed anymore when the "-c" switch is used, or if
       compilation fails.

       See "Support for CHECK blocks" for how to run things when the compile
       phase ends.

       Potential to leak DATA filehandles

       Using the "__DATA__" token creates an implicit filehandle to the file
       that contains the token.  It is the programs responsibility to close
       it when it is done reading from it.

       This caveat is now better explained in the documentation.  See perl

New or Changed Diagnostics
       "%s" variable %s masks earlier declaration in same %s
	   (W misc) A "my" or "our" variable has been redeclared in the cur
	   rent scope or statement, effectively eliminating all access to the
	   previous instance.  This is almost always a typographical error.
	   Note that the earlier variable will still exist until the end of
	   the scope or until all closure referents to it are destroyed.

       "my sub" not yet implemented
	   (F) Lexically scoped subroutines are not yet implemented.  Dont
	   try that yet.

       "our" variable %s redeclared
	   (W misc) You seem to have already declared the same global once
	   before in the current lexical scope.

       ! allowed only after types %s
	   (F) The ! is allowed in pack() and unpack() only after certain
	   types.  See "pack" in perlfunc.

       / cannot take a count
	   (F) You had an unpack template indicating a counted-length string,
	   but you have also specified an explicit size for the string.  See
	   "pack" in perlfunc.

       / must be followed by a, A or Z
	   (F) You had an unpack template indicating a counted-length string,
	   which must be followed by one of the letters a, A or Z to indicate
	   what sort of string is to be unpacked.  See "pack" in perlfunc.

       / must be followed by a*, A* or Z*
	   (F) You had a pack template indicating a counted-length string,
	   Currently the only things that can have their length counted are
	   a*, A* or Z*.  See "pack" in perlfunc.

       / must follow a numeric type
	   (F) You had an unpack template that contained a #, but this did
	   not follow some numeric unpack specification.  See "pack" in perl

       /%s/: Unrecognized escape \\%c passed through
	   (W regexp) You used a backslash-character combination which is not
	   recognized by Perl.	This combination appears in an interpolated
	   variable or a ""-delimited regular expression.  The character was
	   understood literally.

       /%s/: Unrecognized escape \\%c in character class passed through
	   (W regexp) You used a backslash-character combination which is not
	   recognized by Perl inside character classes.  The character was
	   understood literally.

       /%s/ should probably be written as "%s"
	   (W syntax) You have used a pattern where Perl expected to find a
	   string, as in the first argument to "join".	Perl will treat the
	   true or false result of matching the pattern against $_ as the
	   string, which is probably not what you had in mind.

       %s() called too early to check prototype
	   (W prototype) Youve called a function that has a prototype before
	   the parser saw a definition or declaration for it, and Perl could
	   not check that the call conforms to the prototype.  You need to
	   either add an early prototype declaration for the subroutine in
	   question, or move the subroutine definition ahead of the call to
	   get proper prototype checking.  Alternatively, if you are certain
	   that youre calling the function correctly, you may put an amper
	   sand before the name to avoid the warning.  See perlsub.

       %s argument is not a HASH or ARRAY element
	   (F) The argument to exists() must be a hash or array element, such


       %s argument is not a HASH or ARRAY element or slice
	   (F) The argument to delete() must be either a hash or array ele
	   ment, such as:


	   or a hash or array slice, such as:

	       @foo[$bar, $baz, $xyzzy]
	       @{$ref->[12]}{"susie", "queue"}

       %s argument is not a subroutine name
	   (F) The argument to exists() for "exists &sub" must be a subroutine
	   name, and not a subroutine call.  "exists &sub()" will generate
	   this error.

       %s package attribute may clash with future reserved word: %s
	   (W reserved) A lowercase attribute name was used that had a pack
	   age-specific handler.  That name might have a meaning to Perl
	   itself some day, even though it doesnt yet.	Perhaps you should
	   use a mixed-case attribute name, instead.  See attributes.

       (in cleanup) %s
	   (W misc) This prefix usually indicates that a DESTROY() method
	   raised the indicated exception.  Since destructors are usually
	   called by the system at arbitrary points during execution, and
	   often a vast number of times, the warning is issued only once for
	   any number of failures that would otherwise result in the same mes
	   sage being repeated.

	   Failure of user callbacks dispatched using the "G_KEEPERR" flag
	   could also result in this warning.  See "G_KEEPERR" in perlcall.

       <> should be quotes
	   (F) You wrote "require " when you should have written
	   "require file".

       Attempt to join self
	   (F) You tried to join a thread from within itself, which is an
	   impossible task.  You may be joining the wrong thread, or you may
	   need to move the join() to some other thread.

       Bad evalled substitution pattern
	   (F) Youve used the /e switch to evaluate the replacement for a
	   substitution, but perl found a syntax error in the code to evalu
	   ate, most likely an unexpected right brace }.

       Bad realloc() ignored
	   (S) An internal routine called realloc() on something that had
	   never been malloc()ed in the first place. Mandatory, but can be
	   disabled by setting environment variable "PERL_BADFREE" to 1.

       Bareword found in conditional
	   (W bareword) The compiler found a bareword where it expected a con
	   ditional, which often indicates that an || or && was parsed as part
	   of the last argument of the previous construct, for example:

	       open FOO || die;

	   It may also indicate a misspelled constant that has been inter
	   preted as a bareword:

	       use constant TYPO => 1;
	       if (TYOP) { print "foo" }

	   The "strict" pragma is useful in avoiding such errors.

       Binary number > 0b11111111111111111111111111111111 non-portable
	   (W portable) The binary number you specified is larger than 2**32-1
	   (4294967295) and therefore non-portable between systems.  See perl
	   port for more on portability concerns.

       Bit vector size > 32 non-portable
	   (W portable) Using bit vector sizes larger than 32 is non-portable.

       Buffer overflow in prime_env_iter: %s
	   (W internal) A warning peculiar to VMS.  While Perl was preparing
	   to iterate over %ENV, it encountered a logical name or symbol
	   definition which was too long, so it was truncated to the string

       Cant check filesystem of script "%s"
	   (P) For some reason you cant check the filesystem of the script
	   for nosuid.

       Cant declare class for non-scalar %s in "%s"
	   (S) Currently, only scalar variables can declared with a specific
	   class qualifier in a "my" or "our" declaration.  The semantics may
	   be extended for other types of variables in future.

       Cant declare %s in "%s"
	   (F) Only scalar, array, and hash variables may be declared as "my"
	   or "our" variables.	They must have ordinary identifiers as names.

       Cant ignore signal CHLD, forcing to default
	   (W signal) Perl has detected that it is being run with the SIGCHLD
	   signal (sometimes known as SIGCLD) disabled.  Since disabling this
	   signal will interfere with proper determination of exit status of
	   child processes, Perl has reset the signal to its default value.
	   This situation typically indicates that the parent program under
	   which Perl may be running (e.g., cron) is being very careless.

       Cant modify non-lvalue subroutine call
	   (F) Subroutines meant to be used in lvalue context should be
	   declared as such, see "Lvalue subroutines" in perlsub.

       Cant read CRTL environ
	   (S) A warning peculiar to VMS.  Perl tried to read an element of
	   %ENV from the CRTLs internal environment array and discovered the
	   array was missing.  You need to figure out where your CRTL mis
	   placed its environ or define PERL_ENV_TABLES (see perlvms) so that
	   environ is not searched.

       Cant remove %s: %s, skipping file
	   (S) You requested an inplace edit without creating a backup file.
	   Perl was unable to remove the original file to replace it with the
	   modified file.  The file was left unmodified.

       Cant return %s from lvalue subroutine
	   (F) Perl detected an attempt to return illegal lvalues (such as
	   temporary or readonly values) from a subroutine used as an lvalue.
	   This is not allowed.

       Cant weaken a nonreference
	   (F) You attempted to weaken something that was not a reference.
	   Only references can be weakened.

       Character class [:%s:] unknown
	   (F) The class in the character class [: :] syntax is unknown.  See

       Character class syntax [%s] belongs inside character classes
	   (W unsafe) The character class constructs [: :], [= =], and [. .]
	   go inside character classes, the [] are part of the construct, for
	   example: /[012[:alpha:]345]/.  Note that [= =] and [. .]  are not
	   currently implemented; they are simply placeholders for future

       Constant is not %s reference
	   (F) A constant value (perhaps declared using the "use constant"
	   pragma) is being dereferenced, but it amounts to the wrong type of
	   reference.  The message indicates the type of reference that was
	   expected. This usually indicates a syntax error in dereferencing
	   the constant value.	See "Constant Functions" in perlsub and con

       constant(%s): %s
	   (F) The parser found inconsistencies either while attempting to
	   define an overloaded constant, or when trying to find the character
	   name specified in the "\N{...}" escape.  Perhaps you forgot to load
	   the corresponding "overload" or "charnames" pragma?	See charnames
	   and overload.

       CORE::%s is not a keyword
	   (F) The CORE:: namespace is reserved for Perl keywords.

       defined(@array) is deprecated
	   (D) defined() is not usually useful on arrays because it checks for
	   an undefined scalar value.  If you want to see if the array is
	   empty, just use "if (@array) { # not empty }" for example.

       defined(%hash) is deprecated
	   (D) defined() is not usually useful on hashes because it checks for
	   an undefined scalar value.  If you want to see if the hash is
	   empty, just use "if (%hash) { # not empty }" for example.

       Did not produce a valid header
	   See Server error.

       (Did you mean "local" instead of "our"?)
	   (W misc) Remember that "our" does not localize the declared global
	   variable.  You have declared it again in the same lexical scope,
	   which seems superfluous.

       Document contains no data
	   See Server error.

       entering effective %s failed
	   (F) While under the "use filetest" pragma, switching the real and
	   effective uids or gids failed.

       false [] range "%s" in regexp
	   (W regexp) A character class range must start and end at a literal
	   character, not another character class like "\d" or "[:alpha:]".
	   The "-" in your false range is interpreted as a literal "-".  Con
	   sider quoting the "-",  "\-".  See perlre.

       Filehandle %s opened only for output
	   (W io) You tried to read from a filehandle opened only for writing.
	   If you intended it to be a read/write filehandle, you needed to
	   open it with "+<" or "+>" or "+>>" instead of with "<" or nothing.
	   If you intended only to read from the file, use "<".  See "open" in

       flock() on closed filehandle %s
	   (W closed) The filehandle youre attempting to flock() got itself
	   closed some time before now.  Check your logic flow.  flock() oper
	   ates on filehandles.  Are you attempting to call flock() on a
	   dirhandle by the same name?

       Global symbol "%s" requires explicit package name
	   (F) Youve said "use strict vars", which indicates that all vari
	   ables must either be lexically scoped (using "my"), declared
	   beforehand using "our", or explicitly qualified to say which pack
	   age the global variable is in (using "::").

       Hexadecimal number > 0xffffffff non-portable
	   (W portable) The hexadecimal number you specified is larger than
	   2**32-1 (4294967295) and therefore non-portable between systems.
	   See perlport for more on portability concerns.

       Ill-formed CRTL environ value "%s"
	   (W internal) A warning peculiar to VMS.  Perl tried to read the
	   CRTLs internal environ array, and encountered an element without
	   the "=" delimiter used to separate keys from values.  The element
	   is ignored.

       Ill-formed message in prime_env_iter: |%s|
	   (W internal) A warning peculiar to VMS.  Perl tried to read a logi
	   cal name or CLI symbol definition when preparing to iterate over
	   %ENV, and didnt see the expected delimiter between key and value,
	   so the line was ignored.

       Illegal binary digit %s
	   (F) You used a digit other than 0 or 1 in a binary number.

       Illegal binary digit %s ignored
	   (W digit) You may have tried to use a digit other than 0 or 1 in a
	   binary number.  Interpretation of the binary number stopped before
	   the offending digit.

       Illegal number of bits in vec
	   (F) The number of bits in vec() (the third argument) must be a
	   power of two from 1 to 32 (or 64, if your platform supports that).

       Integer overflow in %s number
	   (W overflow) The hexadecimal, octal or binary number you have spec
	   ified either as a literal or as an argument to hex() or oct() is
	   too big for your architecture, and has been converted to a floating
	   point number.  On a 32-bit architecture the largest hexadecimal,
	   octal or binary number representable without overflow is
	   0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111
	   respectively.  Note that Perl transparently promotes all numbers to
	   a floating point representation internally--subject to loss of pre
	   cision errors in subsequent operations.

       Invalid %s attribute: %s
	   The indicated attribute for a subroutine or variable was not recog
	   nized by Perl or by a user-supplied handler.  See attributes.

       Invalid %s attributes: %s
	   The indicated attributes for a subroutine or variable were not rec
	   ognized by Perl or by a user-supplied handler.  See attributes.

       invalid [] range "%s" in regexp
	   The offending range is now explicitly displayed.

       Invalid separator character %s in attribute list
	   (F) Something other than a colon or whitespace was seen between the
	   elements of an attribute list.  If the previous attribute had a
	   parenthesised parameter list, perhaps that list was terminated too
	   soon.  See attributes.

       Invalid separator character %s in subroutine attribute list
	   (F) Something other than a colon or whitespace was seen between the
	   elements of a subroutine attribute list.  If the previous attribute
	   had a parenthesised parameter list, perhaps that list was termi
	   nated too soon.

       leaving effective %s failed
	   (F) While under the "use filetest" pragma, switching the real and
	   effective uids or gids failed.

       Lvalue subs returning %s not implemented yet
	   (F) Due to limitations in the current implementation, array and
	   hash values cannot be returned in subroutines used in lvalue con
	   text.  See "Lvalue subroutines" in perlsub.

       Method %s not permitted
	   See Server error.

       Missing %sbrace%s on \N{}
	   (F) Wrong syntax of character name literal "\N{charname}" within
	   double-quotish context.

       Missing command in piped open
	   (W pipe) You used the "open(FH, "| command")" or "open(FH, "command
	   |")" construction, but the command was missing or blank.

       Missing name in "my sub"
	   (F) The reserved syntax for lexically scoped subroutines requires
	   that they have a name with which they can be found.

       No %s specified for -%c
	   (F) The indicated command line switch needs a mandatory argument,
	   but you havent specified one.

       No package name allowed for variable %s in "our"
	   (F) Fully qualified variable names are not allowed in "our" decla
	   rations, because that doesnt make much sense under existing seman
	   tics.  Such syntax is reserved for future extensions.

       No space allowed after -%c
	   (F) The argument to the indicated command line switch must follow
	   immediately after the switch, without intervening spaces.

       no UTC offset information; assuming local time is UTC
	   (S) A warning peculiar to VMS.  Perl was unable to find the local
	   timezone offset, so its assuming that local system time is equiva
	   lent to UTC.  If its not, define the logical name SYS$TIME
	   ZONE_DIFFERENTIAL to translate to the number of seconds which need
	   to be added to UTC to get local time.

       Octal number > 037777777777 non-portable
	   (W portable) The octal number you specified is larger than 2**32-1
	   (4294967295) and therefore non-portable between systems.  See perl
	   port for more on portability concerns.

	   See also perlport for writing portable code.

       panic: del_backref
	   (P) Failed an internal consistency check while trying to reset a
	   weak reference.

       panic: kid popen errno read
	   (F) forked child returned an incomprehensible message about its

       panic: magic_killbackrefs
	   (P) Failed an internal consistency check while trying to reset all
	   weak references to an object.

       Parentheses missing around "%s" list
	   (W parenthesis) You said something like

	       my $foo, $bar = @_;

	   when you meant

	       my ($foo, $bar) = @_;

	   Remember that "my", "our", and "local" bind tighter than comma.

       Possible unintended interpolation of %s in string
	   (W ambiguous) It used to be that Perl would try to guess whether
	   you wanted an array interpolated or a literal @.  It no longer does
	   this; arrays are now always interpolated into strings.  This means
	   that if you try something like:

		   print "fred@example.com";

	   and the array @example doesnt exist, Perl is going to print
	   "fred.com", which is probably not what you wanted.  To get a lit
	   eral "@" sign in a string, put a backslash before it, just as you
	   would to get a literal "$" sign.

       Possible Y2K bug: %s
	   (W y2k) You are concatenating the number 19 with another number,
	   which could be a potential Year 2000 problem.

       pragma "attrs" is deprecated, use "sub NAME : ATTRS" instead
	   (W deprecated) You have written something like this:

	       sub doit
		   use attrs qw(locked);

	   You should use the new declaration syntax instead.

	       sub doit : locked

	   The "use attrs" pragma is now obsolete, and is only provided for
	   backward-compatibility. See "Subroutine Attributes" in perlsub.

       Premature end of script headers
	   See Server error.

       Repeat count in pack overflows
	   (F) You cant specify a repeat count so large that it overflows
	   your signed integers.  See "pack" in perlfunc.

       Repeat count in unpack overflows
	   (F) You cant specify a repeat count so large that it overflows
	   your signed integers.  See "unpack" in perlfunc.

       realloc() of freed memory ignored
	   (S) An internal routine called realloc() on something that had
	   already been freed.

       Reference is already weak
	   (W misc) You have attempted to weaken a reference that is already
	   weak.  Doing so has no effect.

       setpgrp cant take arguments
	   (F) Your system has the setpgrp() from BSD 4.2, which takes no
	   arguments, unlike POSIX setpgid(), which takes a process ID and
	   process group ID.

       Strange *+?{} on zero-length expression
	   (W regexp) You applied a regular expression quantifier in a place
	   where it makes no sense, such as on a zero-width assertion.	Try
	   putting the quantifier inside the assertion instead.  For example,
	   the way to match "abc" provided that it is followed by three repe
	   titions of "xyz" is "/abc(?=(?:xyz){3})/", not "/abc(?=xyz){3}/".

       switching effective %s is not implemented
	   (F) While under the "use filetest" pragma, we cannot switch the
	   real and effective uids or gids.

       This Perl cant reset CRTL environ elements (%s)
       This Perl cant set CRTL environ elements (%s=%s)
	   (W internal) Warnings peculiar to VMS.  You tried to change or
	   delete an element of the CRTLs internal environ array, but your
	   copy of Perl wasnt built with a CRTL that contained the setenv()
	   function.  Youll need to rebuild Perl with a CRTL that does, or
	   redefine PERL_ENV_TABLES (see perlvms) so that the environ array
	   isnt the target of the change to %ENV which produced the warning.

       Too late to run %s block
	   (W void) A CHECK or INIT block is being defined during run time
	   proper, when the opportunity to run them has already passed.  Per
	   haps you are loading a file with "require" or "do" when you should
	   be using "use" instead.  Or perhaps you should put the "require" or
	   "do" inside a BEGIN block.

       Unknown open() mode %s
	   (F) The second argument of 3-argument open() is not among the list
	   of valid modes: "<", ">", ">>", "+<", "+>", "+>>", "-|", "|-".

       Unknown process %x sent message to prime_env_iter: %s
	   (P) An error peculiar to VMS.  Perl was reading values for %ENV
	   before iterating over it, and someone else stuck a message in the
	   stream of data Perl expected.  Someones very confused, or perhaps
	   trying to subvert Perls population of %ENV for nefarious purposes.

       Unrecognized escape \\%c passed through
	   (W misc) You used a backslash-character combination which is not
	   recognized by Perl.	The character was understood literally.

       Unterminated attribute parameter in attribute list
	   (F) The lexer saw an opening (left) parenthesis character while
	   parsing an attribute list, but the matching closing (right) paren
	   thesis character was not found.  You may need to add (or remove) a
	   backslash character to get your parentheses to balance.  See

       Unterminated attribute list
	   (F) The lexer found something other than a simple identifier at the
	   start of an attribute, and it wasnt a semicolon or the start of a
	   block.  Perhaps you terminated the parameter list of the previous
	   attribute too soon.	See attributes.

       Unterminated attribute parameter in subroutine attribute list
	   (F) The lexer saw an opening (left) parenthesis character while
	   parsing a subroutine attribute list, but the matching closing
	   (right) parenthesis character was not found.  You may need to add
	   (or remove) a backslash character to get your parentheses to bal

       Unterminated subroutine attribute list
	   (F) The lexer found something other than a simple identifier at the
	   start of a subroutine attribute, and it wasnt a semicolon or the
	   start of a block.  Perhaps you terminated the parameter list of the
	   previous attribute too soon.

       Value of CLI symbol "%s" too long
	   (W misc) A warning peculiar to VMS.	Perl tried to read the value
	   of an %ENV element from a CLI symbol table, and found a resultant
	   string longer than 1024 characters.	The return value has been
	   truncated to 1024 characters.

       Version number must be a constant number
	   (P) The attempt to translate a "use Module n.n LIST" statement into
	   its equivalent "BEGIN" block found an internal inconsistency with
	   the version number.

New tests
	   Compatibility tests for "sub : attrs" vs the older "use attrs".

	   Tests for new environment scalar capability (e.g., "use Env

	   Tests for new environment array capability (e.g., "use Env

	   IO constants (SEEK_*, _IO*).

	   Directory-related IO methods (new, read, close, rewind, tied

	   INET sockets with multi-homed hosts.

	   IO poll().

	   UNIX sockets.

	   Regression tests for "my ($x,@y,%z) : attrs" and .

	   File test operators.

	   Verify operations that access pad objects (lexicals and tempo

	   Verify "exists &sub" operations.

Incompatible Changes
       Perl Source Incompatibilities

       Beware that any new warnings that have been added or old ones that have
       been enhanced are not considered incompatible changes.

       Since all new warnings must be explicitly requested via the "-w" switch
       or the "warnings" pragma, it is ultimately the programmers responsi
       bility to ensure that warnings are enabled judiciously.

       CHECK is a new keyword
	   All subroutine definitions named CHECK are now special.  See
	   "/"Support for CHECK blocks"" for more information.

       Treatment of list slices of undef has changed
	   There is a potential incompatibility in the behavior of list slices
	   that are comprised entirely of undefined values.  See "Behavior of
	   list slices is more consistent".

       Format of $English::PERL_VERSION is different
	   The English module now sets $PERL_VERSION to $^V (a string value)
	   rather than $] (a numeric value).  This is a potential incompati
	   bility.  Send us a report via perlbug if you are affected by this.

	   See "Improved Perl version numbering system" for the reasons for
	   this change.

       Literals of the form 1.2.3 parse differently
	   Previously, numeric literals with more than one dot in them were
	   interpreted as a floating point number concatenated with one or
	   more numbers.  Such "numbers" are now parsed as strings composed of
	   the specified ordinals.

	   For example, "print 97.98.99" used to output 97.9899 in earlier
	   versions, but now prints "abc".

	   See "Support for strings represented as a vector of ordinals".

       Possibly changed pseudo-random number generator
	   Perl programs that depend on reproducing a specific set of pseudo-
	   random numbers may now produce different output due to improvements
	   made to the rand() builtin.	You can use "sh Configure -Drand
	   func=rand" to obtain the old behavior.

	   See "Better pseudo-random number generator".

       Hashing function for hash keys has changed
	   Even though Perl hashes are not order preserving, the apparently
	   random order encountered when iterating on the contents of a hash
	   is actually determined by the hashing algorithm used.  Improvements
	   in the algorithm may yield a random order that is different from
	   that of previous versions, especially when iterating on hashes.

	   See "Better worst-case behavior of hashes" for additional informa

       "undef" fails on read only values
	   Using the "undef" operator on a readonly value (such as $1) has the
	   same effect as assigning "undef" to the readonly value--it throws
	   an exception.

       Close-on-exec bit may be set on pipe and socket handles
	   Pipe and socket handles are also now subject to the close-on-exec
	   behavior determined by the special variable $^F.

	   See "More consistent close-on-exec behavior".

       Writing "$$1" to mean "${$}1" is unsupported
	   Perl 5.004 deprecated the interpretation of $$1 and similar within
	   interpolated strings to mean "$$ . "1"", but still allowed it.

	   In Perl 5.6.0 and later, "$$1" always means "${$1}".

       delete(), each(), values() and "\(%h)"
	   operate on aliases to values, not copies

	   delete(), each(), values() and hashes (e.g. "\(%h)") in a list con
	   text return the actual values in the hash, instead of copies (as
	   they used to in earlier versions).  Typical idioms for using these
	   constructs copy the returned values, but this can make a signifi
	   cant difference when creating references to the returned values.
	   Keys in the hash are still returned as copies when iterating on a

	   See also "delete(), each(), values() and hash iteration are

       vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS
	   vec() generates a run-time error if the BITS argument is not a
	   valid power-of-two integer.

       Text of some diagnostic output has changed
	   Most references to internal Perl operations in diagnostics have
	   been changed to be more descriptive.  This may be an issue for pro
	   grams that may incorrectly rely on the exact text of diagnostics
	   for proper functioning.

       "%@" has been removed
	   The undocumented special variable "%@" that used to accumulate
	   "background" errors (such as those that happen in DESTROY()) has
	   been removed, because it could potentially result in memory leaks.

       Parenthesized not() behaves like a list operator
	   The "not" operator now falls under the "if it looks like a func
	   tion, it behaves like a function" rule.

	   As a result, the parenthesized form can be used with "grep" and
	   "map".  The following construct used to be a syntax error before,
	   but it works as expected now:

	       grep not($_), @things;

	   On the other hand, using "not" with a literal list slice may not
	   work.  The following previously allowed construct:

	       print not (1,2,3)[0];

	   needs to be written with additional parentheses now:

	       print not((1,2,3)[0]);

	   The behavior remains unaffected when "not" is not followed by

       Semantics of bareword prototype "(*)" have changed
	   The semantics of the bareword prototype "*" have changed.  Perl
	   5.005 always coerced simple scalar arguments to a typeglob, which
	   wasnt useful in situations where the subroutine must distinguish
	   between a simple scalar and a typeglob.  The new behavior is to not
	   coerce bareword arguments to a typeglob.  The value will always be
	   visible as either a simple scalar or as a reference to a typeglob.

	   See "More functional bareword prototype (*)".

       Semantics of bit operators may have changed on 64-bit platforms
	   If your platform is either natively 64-bit or if Perl has been con
	   figured to used 64-bit integers, i.e., $Config{ivsize} is 8, there
	   may be a potential incompatibility in the behavior of bitwise
	   numeric operators (& | ^ ~ << >>).  These operators used to
	   strictly operate on the lower 32 bits of integers in previous ver
	   sions, but now operate over the entire native integral width.  In
	   particular, note that unary "~" will produce different results on
	   platforms that have different $Config{ivsize}.  For portability, be
	   sure to mask off the excess bits in the result of unary "~", e.g.,
	   "~$x & 0xffffffff".

	   See "Bit operators support full native integer width".

       More builtins taint their results
	   As described in "Improved security features", there may be more
	   sources of taint in a Perl program.

	   To avoid these new tainting behaviors, you can build Perl with the
	   Configure option "-Accflags=-DINCOMPLETE_TAINTS".  Beware that the
	   ensuing perl binary may be insecure.

       C Source Incompatibilities

	   Release 5.005 grandfathered old global symbol names by providing
	   preprocessor macros for extension source compatibility.  As of
	   release 5.6.0, these preprocessor definitions are not available by
	   default.  You need to explicitly compile perl with "-DPERL_POLLUTE"
	   to get these definitions.  For extensions still using the old sym
	   bols, this option can be specified via MakeMaker:

	       perl Makefile.PL POLLUTE=1

	   This new build option provides a set of macros for all API func
	   tions such that an implicit interpreter/thread context argument is
	   passed to every API function.  As a result of this, something like
	   "sv_setsv(foo,bar)" amounts to a macro invocation that actually
	   translates to something like "Perl_sv_setsv(my_perl,foo,bar)".
	   While this is generally expected to not have any significant source
	   compatibility issues, the difference between a macro and a real
	   function call will need to be considered.

	   This means that there is a source compatibility issue as a result
	   of this if your extensions attempt to use pointers to any of the
	   Perl API functions.

	   Note that the above issue is not relevant to the default build of
	   Perl, whose interfaces continue to match those of prior versions
	   (but subject to the other options described here).

	   See "The Perl API" in perlguts for detailed information on the ram
	   ifications of building Perl with this option.

	       NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
	       with one of -Dusethreads, -Dusemultiplicity, or both.  It is not
	       intended to be enabled by users at this time.

	   Enabling Perls malloc in release 5.005 and earlier caused the
	   namespace of the systems malloc family of functions to be usurped
	   by the Perl versions, since by default they used the same names.
	   Besides causing problems on platforms that do not allow these func
	   tions to be cleanly replaced, this also meant that the system ver
	   sions could not be called in programs that used Perls malloc.
	   Previous versions of Perl have allowed this behaviour to be sup
	   pressed with the HIDEMYMALLOC and EMBEDMYMALLOC preprocessor defi

	   As of release 5.6.0, Perls malloc family of functions have default
	   names distinct from the system versions.  You need to explicitly
	   compile perl with "-DPERL_POLLUTE_MALLOC" to get the older
	   behaviour.  HIDEMYMALLOC and EMBEDMYMALLOC have no effect, since
	   the behaviour they enabled is now the default.

	   Note that these functions do not constitute Perls memory
	   allocation API.  See "Memory Allocation" in perlguts for further
	   information about that.

       Compatible C Source API Changes

	   The cpp macros "PERL_REVISION", "PERL_VERSION", and "PERL_SUBVER
	   SION" are now available by default from perl.h, and reflect the
	   base revision, patchlevel, and subversion respectively.
	   "PERL_REVISION" had no prior equivalent, while "PERL_VERSION" and
	   "PERL_SUBVERSION" were previously available as "PATCHLEVEL" and

	   The new names cause less pollution of the cpp namespace and reflect
	   what the numbers have come to stand for in common practice.	For
	   compatibility, the old names are still supported when patchlevel.h
	   is explicitly included (as required before), so there is no source
	   incompatibility from the change.

       Binary Incompatibilities

       In general, the default build of this release is expected to be binary
       compatible for extensions built with the 5.005 release or its mainte
       nance versions.	However, specific platforms may have broken binary
       compatibility due to changes in the defaults used in hints files.
       Therefore, please be sure to always check the platform-specific README
       files for any notes to the contrary.

       The usethreads or usemultiplicity builds are not binary compatible with
       the corresponding builds in 5.005.

       On platforms that require an explicit list of exports (AIX, OS/2 and
       Windows, among others), purely internal symbols such as parser func
       tions and the run time opcodes are not exported by default.  Perl 5.005
       used to export all functions irrespective of whether they were consid
       ered part of the public API or not.

       For the full list of public API functions, see perlapi.

Known Problems
       Thread test failures

       The subtests 19 and 20 of lib/thr5005.t test 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 didnt have
       these tests.

       EBCDIC platforms not supported

       In earlier releases of Perl, EBCDIC environments like OS390 (also known
       as Open Edition MVS) and VM-ESA were supported.	Due to changes
       required by the UTF-8 (Unicode) support, the EBCDIC platforms are not
       supported in Perl 5.6.0.

       In 64-bit HP-UX the lib/io_multihomed test may hang

       The lib/io_multihomed test may hang in HP-UX if Perl has been config
       ured to be 64-bit.  Because other 64-bit platforms do not hang in this
       test, HP-UX is suspect.	All other tests pass in 64-bit HP-UX.  The
       test attempts to create and connect to "multihomed" sockets (sockets
       which have multiple IP addresses).

       NEXTSTEP 3.3 POSIX test failure

       In NEXTSTEP 3.3p2 the implementation of the strftime(3) in the operat
       ing system libraries is buggy: the %j format numbers the days of a
       month starting from zero, which, while being logical to programmers,
       will cause the subtests 19 to 27 of the lib/posix test may fail.

       Tru64 (aka Digital UNIX, aka DEC OSF/1) lib/sdbm test failure with gcc

       If compiled with gcc 2.95 the lib/sdbm test will fail (dump core).  The
       cure is to use the vendor cc, it comes with the operating system and
       produces good code.

       UNICOS/mk CC failures during Configure run

       In UNICOS/mk the following errors may appear during the Configure run:

	       Guessing which symbols your C compiler and preprocessor define...
	       CC-20 cc: ERROR File = try.c, Line = 3
		 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
	       4 errors detected in the compilation of "try.c".

       The culprit is the broken awk of UNICOS/mk.  The effect is fortunately
       rather mild: Perl itself is not adversely affected by the error, only
       the h2ph utility coming with Perl, and that is rather rarely needed
       these days.

       Arrow operator and arrays

       When the left argument to the arrow operator "->" is an array, or the
       "scalar" operator operating on an array, the result of the operation
       must be considered erroneous. For example:


       These expressions will get run-time errors in some future release of

       Experimental features

       As discussed above, many features are still experimental.  Interfaces
       and implementation of these features are subject to change, and in
       extreme cases, even subject to removal in some future release of Perl.
       These features include the following:

       64-bit support
       Lvalue subroutines
       Weak references
       The pseudo-hash data type
       The Compiler suite
       Internal implementation of file globbing
       The DB module
       The regular expression code constructs:
	   "(?{ code })" and "(??{ code })"

Obsolete Diagnostics
       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: "\[:" and ":\]".

       Ill-formed logical name |%s| in prime_env_iter
	   (W) A warning peculiar to VMS.  A logical name was encountered when
	   preparing to iterate over %ENV which violates the syntactic rules
	   governing logical names.  Because it cannot be translated normally,
	   it is skipped, and will not appear in %ENV.	This may be a benign
	   occurrence, as some software packages might directly modify logical
	   name tables and introduce nonstandard names, or it may indicate
	   that a logical name table has been corrupted.

       In string, @%s now must be written as \@%s
	   The description of this error used to say:

		   (Someday it will simply assume that an unbackslashed @
		    interpolates an array.)

	   That day has come, and this fatal error has been removed.  It has
	   been replaced by a non-fatal warning instead.  See "Arrays now
	   always interpolate into double-quoted strings" for details.

       Probable precedence problem on %s
	   (W) The compiler found a bareword where it expected a conditional,
	   which often indicates that an || or && was parsed as part of the
	   last argument of the previous construct, for example:

	       open FOO || die;

       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, itll blow
	   up.	Usually when you want a regular expression this big, there is
	   a better way to do it with multiple statements.  See perlre.

       Use of "$$" to mean "${$}" is deprecated
	   (D) Perl versions before 5.004 misinterpreted any type marker fol
	   lowed by "$" and a digit.  For example, "$$0" was incorrectly taken
	   to mean "${$}0" instead of "${$0}".	This bug is (mostly) fixed in
	   Perl 5.004.

	   However, the developers of Perl 5.004 could not fix this bug com
	   pletely, because at least two widely-used modules depend on the old
	   meaning of "$$0" in a string.  So Perl 5.004 still interprets
	   "$$" in the old (broken) way inside strings; but it gener
	   ates this message as a warning.  And in Perl 5.005, this special
	   treatment will cease.

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

       If you believe you have an unreported bug, please run the perlbug pro
       gram 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 Gurusamy Sarathy , with many contribu
       tions from The Perl Porters.

       Send omissions or corrections to .

perl v5.8.8			  2008-04-25			PERL56DELTA(1)

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