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PERL58DELTA(1)

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NAME    [Toc]    [Back]

       perl58delta - what is new for perl v5.8.0

DESCRIPTION    [Toc]    [Back]

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

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

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

       You can see the list of changes in the 5.6.1 release (both
       from the 5.005_03 release and the 5.6.0 release) by reading
 perl561delta.

Highlights In 5.8.0    [Toc]    [Back]

       o   Better Unicode support

       o   New IO Implementation

       o   New Thread Implementation

       o   Better Numeric Accuracy

       o   Safe Signals

       o   Many New Modules

       o   More Extensive Regression Testing

Incompatible Changes    [Toc]    [Back]

       Binary Incompatibility

       Perl 5.8 is not binary compatible with earlier releases of    [Toc]    [Back]
       Perl.

       You have to recompile your XS modules.    [Toc]    [Back]

       (Pure Perl modules should continue to work.)

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

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

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

       64-bit platforms and malloc

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

       AIX Dynaloading    [Toc]    [Back]

       The AIX dynaloading now uses in AIX releases 4.3 and newer
       the native dlopen interface of AIX instead of the old emulated
 interface.  This change will probably break backward
       compatibility with compiled modules.  The change was made
       to make Perl more compliant with other applications like
       mod_perl which are using the AIX native interface.

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

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

       Socket Extension Dynamic in VMS    [Toc]    [Back]

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

       IEEE-format Floating Point Default on OpenVMS Alpha    [Toc]    [Back]

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

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

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

       This was found to be an inconvenient interface, and in
       Perl 5.8 the Unicode model has completely changed: now the
       "Unicodeness" is bound to the data itself, and for most of
       the time "use utf8" is not needed at all.  The only
       remaining use of "use utf8" is when the Perl script itself
       has been written in the UTF-8 encoding of Unicode.  (UTF-8
       has not been made the default since there are many Perl
       scripts out there that are using various national eightbit
 character sets, which would be illegal in UTF-8.)

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

       New Unicode Properties    [Toc]    [Back]

       Unicode scripts are now supported. Scripts are similar to
       (and superior to) Unicode blocks. The difference between
       scripts and blocks is that scripts are the glyphs used by
       a language or a group of languages, while the blocks are
       more artificial groupings of (mostly) 256 characters based
       on the Unicode numbering.

       In general, scripts are more inclusive, but not universally
 so. For example, while the script "Latin" includes
       all the Latin characters and their various diacriticadorned
 versions, it does not include the various punctuation
 or digits (since they are not solely "Latin").

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

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

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

       pack/unpack D/F recycled

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

       glob() now returns filenames in alphabetical order

       The list of filenames from glob() (or <...>) is now by
       default sorted alphabetically to be csh-compliant (which
       is what happened before in most UNIX platforms).
       (bsd_glob() does still sort platform natively, ASCII or
       EBCDIC, unless GLOB_ALPHASORT is specified.) [561]

       Deprecations    [Toc]    [Back]


       o   The semantics of bless(REF, REF) were unclear and
           until someone proves it to make some sense, it is forbidden.


       o   The obsolete chat2 library that should never have been
           allowed to escape the laboratory has been decommissioned.


       o   Using chdir("") or chdir(undef) instead of explicit
           chdir() is doubtful.  A failure (think
           chdir(some_function()) can lead into unintended
           chdir() to the home directory, therefore this
           behaviour is deprecated.

       o   The builtin dump() function has probably outlived most
           of its usefulness.  The core-dumping functionality
           will remain in future available as an explicit call to
           "CORE::dump()", but in future releases the behaviour
           of an unqualified "dump()" call may change.

       o   The very dusty examples in the eg/ directory have been
           removed.  Suggestions for new shiny examples welcome
           but the main issue is that the examples need to be
           documented, tested and (most importantly)  maintained.

       o   The (bogus) escape sequences 8 and 9 now give an
           optional warning ("Unrecognized escape passed
           through").  There is no need to -escape any "0
           character.
       o   The *glob{FILEHANDLE} is deprecated, use *glob{IO}
           instead.

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

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

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

       o   Previous versions of perl and some readings of some
           sections of Camel III implied that the ":raw" "discipline"
 was the inverse of ":crlf".  Turning off "clrfness"
 is no longer enough to make a stream truly
           binary. So the PerlIO ":raw" layer (or "discipline",
           to use the Camel book's older terminology) is now formally
 defined as being equivalent to binmode(FH) -
           which is in turn defined as doing whatever is necessary
  to pass each byte as-is without any translation.
           In particular binmode(FH) - and hence ":raw" - will
           now turn off both CRLF and UTF-8 translation and
           remove other layers (e.g. :encoding()) which would
           modify byte stream.

       o   The current user-visible implementation of pseudohashes
 (the weird use of the first array element) is
           deprecated starting from Perl 5.8.0 and will be
           removed in Perl 5.10.0, and the feature will be implemented
 differently.  Not only is the current interface
           rather ugly, but the current implementation slows down
           normal array and hash use quite noticeably. The
           "fields" pragma interface will remain available.  The
           restricted hashes interface is expected to be the
           replacement interface (see Hash::Util).  If your
           existing programs depends on the underlying implementation,
 consider using Class::PseudoHash from CPAN.

       o   The syntaxes "@a->[...]" and  "%h->{...}" have now
           been deprecated.

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

       o   The 5.005 threads model (module "Thread") is deprecated
 and expected to be removed in Perl 5.10.  Multithreaded
 code should be migrated to the new ithreads
           model (see threads, threads::shared and perlthrtut).

       o   The long deprecated uppercase aliases for the string
           comparison operators (EQ, NE, LT, LE, GE, GT) have now
           been removed.

       o   The tr///C and tr///U features have been removed and
           will not return; the interface was a mistake.  Sorry
           about that.  For similar functionality, see pack('U0',
           ...) and pack('C0', ...). [561]

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

       o   The "exec LIST" and "system LIST" operations now produce
 warnings on tainted data and in some future
           release they will produce fatal errors.

       o   The existing behaviour when localising tied arrays and
           hashes is wrong, and will be changed in a future
           release, so do not rely on the existing behaviour. See
           "Localising Tied Arrays and Hashes Is Broken".

Core Enhancements    [Toc]    [Back]

       Unicode Overhaul

       Unicode in general should be now much more usable than in
       Perl 5.6.0 (or even in 5.6.1).  Unicode can be used in
       hash keys, Unicode in regular expressions should work now,
       Unicode in tr/// should work now, Unicode in I/O should
       work now.  See perluniintro for introduction and perlunicode
 for details.

       o   The Unicode Character Database coming with Perl has
           been upgraded to Unicode 3.2.0.  For more information,
           see http://www.unicode.org/ .  [561+] (5.6.1 has UCD
           3.0.1.)

       o   For developers interested in enhancing Perl's Unicode
           capabilities: almost all the UCD files are included
           with the Perl distribution in the lib/unicore subdirectory.
  The most notable omission, for space considerations,
 is the Unihan database.

       o             The            properties            {Blank}
and                                                   {SpacePerl}
have been
           added. "Blank" is like C isblank(), that is, it contains
 only "horizontal whitespace" (the space character
 is, the newline isn't), and the "SpacePerl" is the
           Unicode equivalent of "{Space} isn't, since
           that includes the vertical tabulator character,
           whereas "oesn't.)

           See "New Unicode Properties" earlier in this document
           for additional information on changes with Unicode
           properties.

       PerlIO is Now The Default    [Toc]    [Back]


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

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

           or on already opened handles via extended "binmode":

              binmode($fh,':encoding(iso-8859-7)');

           The built-in layers are: unix (low level read/write),
           stdio (as in previous Perls), perlio (re-implementation
 of stdio buffering in a portable manner), crlf
           (does CRLF <=> "0 translation as on Win32, but
           available on any platform).  A mmap layer may be
           available if platform supports it (mostly UNIXes).

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

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

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

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

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

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

              open($fh,">:utf8","Uni.txt");
           Note for EBCDIC users: the pseudo layer ":utf8" is
           erroneously named for you since it's not UTF-8 what
           you will be getting but instead UTF-EBCDIC.  See perlunicode,
 utf8, and http://www.unicode.org/uni-
           code/reports/tr16/ for more information.  In future
           releases this naming may change.  See perluniintro for
           more information about UTF-8.

       o   If your environment variables (LC_ALL, LC_CTYPE, LANG)
           look like you want to use UTF-8 (any of the variables
           match "/utf-?8/i"), your STDIN, STDOUT, STDERR handles
           and the default open layer (see open) are marked as
           UTF-8.  (This feature, like other new features that
           combine Unicode and I/O, work only if you are using
           PerlIO, but that's the default.)

           Note that after this Perl really does assume that
           everything is UTF-8: for example if some input handle
           is not, Perl will probably very soon complain about
           the input data like this "Malformed UTF-8 ..." since
           any old eight-bit data is not legal UTF-8.

           Note for code authors: if you want to enable your
           users to use UTF-8 as their default encoding  but in
           your code still have eight-bit I/O streams (such as
           images or zip files), you need to explicitly open() or
           binmode() with ":bytes" (see "open" in perlfunc and
           "binmode" in perlfunc), or you can just use "binmode(FH)"
 (nice for pre-5.8.0 backward compatibility).

       o   File handles can translate character encodings from/to
           Perl's internal Unicode form on read/write via the
           ":encoding()" layer.

       o   File handles can be opened to "in memory" files held
           in Perl scalars via:

              open($fh,'>', ariable) || ...

       o   Anonymous temporary files are available without need
           to 'use FileHandle' or other module via

              open($fh,"+>", undef) || ...

           That is a literal undef, not an undefined value.

       ithreads

       The new interpreter threads ("ithreads" for short) implementation
 of multithreading, by Arthur Bergman, replaces
       the old "5.005 threads" implementation.  In the ithreads
       model any data sharing between threads must be explicit,
       as opposed to the model where data sharing was implicit.
       See threads and threads::shared, and perlthrtut.
       As a part of the ithreads implementation Perl will also
       use any necessary and detectable reentrant libc interfaces.


       Restricted Hashes    [Toc]    [Back]

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

       Safe Signals    [Toc]    [Back]

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

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

       Understanding of Numbers    [Toc]    [Back]

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

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

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

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

               Literal @example now requires backslash

       In versions 5.004_01 through 5.6.0, the error was

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

       The idea here was to get people into the habit of writing
       "fred@example.com" when they wanted a literal "@" sign,
       just as they have always written "Give me back my "
       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 don't backslash the "@".  See
       http://www.plover.com/~mjd/perl/at-error.html for more
       details about the history here.

       Miscellaneous Changes    [Toc]    [Back]


       o   AUTOLOAD is now lvaluable, meaning that you can add
           the :lvalue attribute to AUTOLOAD subroutines and you
           can assign to the AUTOLOAD return value.

       o   The $Config{byteorder} (and corresponding BYTEORDER in
           config.h) was previously wrong in platforms if
           sizeof(long) was 4, but sizeof(IV) was 8.  The byteorder
 was only sizeof(long) bytes long (1234 or 4321),
           but now it is correctly sizeof(IV) bytes long,
           (12345678 or 87654321).  (This problem didn't affect
           Windows platforms.)

           Also, $Config{byteorder} is now computed dynamically--this
 is more robust with "fat binaries" where
           an executable image contains binaries for more than
           one binary platform, and when cross-compiling.

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

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

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

       o   chomp() and chop() are now overridable.  Note, however,
 that their prototype (as given by "prototype("CORE::chomp")"
 is undefined, because it cannot
           be expressed and therefore one cannot really write
           replacements to override these builtins.

       o   END blocks are now run even if you exit/die in a BEGIN
           block.  Internally, the execution of END blocks is now
           controlled  by PL_exit_flags & PERL_EXIT_DESTRUCT_END.
           This enables the new behaviour for Perl embedders.
           This will default in 5.10. See perlembed.

       o   Formats now support zero-padded decimal fields.

       o   Although "you shouldn't do that", it was possible to
           write code that depends on Perl's hashed key order
           (Data::Dumper does this).  The new algorithm
           "One-at-a-Time" produces a different hashed key order.
           More details are in "Performance Enhancements".

       o   lstat(FILEHANDLE) now gives a warning because the
           operation makes no sense.  In future releases this may
           become a fatal error.

       o   Spurious syntax errors generated in certain situations,
 when glob() caused File::Glob to be loaded for
           the first time, have been fixed. [561]

       o   Lvalue subroutines can now return "undef" in list context.
  However, the lvalue subroutine feature still
           remains experimental.  [561+]

       o   A lost warning "Can't declare ... dereference in my"
           has been restored (Perl had it earlier but it became
           lost in later releases.)

       o   A new special regular expression variable has been
           introduced: $^N, which contains the most-recently
           closed group (submatch).

       o   "no Module;" does not produce an error even if Module
           does not have an unimport() method.  This parallels
           the behavior of "use" vis-a-vis "import". [561]
       o   The numerical comparison operators return "undef" if
           either operand is a NaN.  Previously the behaviour was
           unspecified.

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

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

       o   "pack() / unpack()" can now group template letters
           with "()" and then apply repetition/count modifiers on
           the groups.

       o   "pack() / unpack()" can now process the Perl internal
           numeric types: IVs, UVs, NVs-- and also long doubles,
           if supported by the platform.  The template letters
           are "j", "J", "F", and "D".

       o   "pack('U0a*', ...)" can now be used to force a string
           to UTF-8.

       o   my __PACKAGE__ $obj now works. [561]

       o   POSIX::sleep() now returns the number of unslept seconds
 (as the POSIX standard says), as opposed to
           CORE::sleep() which returns the number of slept seconds.


       o   printf() and sprintf() now support parameter reordering
 using the "%+ and "*+ syntaxes.  For
           example

               printf "%2 %10, "foo", "bar";

           will print "bar foo0.  This feature helps in writing
           internationalised software, and in general when the
           order of the parameters can vary.

       o   The () prototype now works properly. [561]

       o   prototype() is now available to implicitly create
 references (useful for example if you want to emulate
 the tie() interface).

       o   A new command-line option, "-t" is available.  It is
           the little brother of "-T": instead of dying on taint
           violations, lexical warnings are given.  This is only
           meant as a temporary debugging aid while securing the
           code of old legacy applications.  This is not a sub-
           stitute for -T.
       o   In other taint news, the "exec LIST" and "system LIST"
           have now been considered too risky (think "exec
           @ARGV": it can start any program with any arguments),
           and now the said forms cause a warning under lexical
           warnings.  You should carefully launder the arguments
           to guarantee their validity.  In future releases of
           Perl the forms will become fatal errors so consider
           starting laundering now.

       o   Tied hash interfaces are now required to have the
           EXISTS and DELETE methods (either own or inherited).

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

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

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

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

       o   Rather than relying on C's argv[0] (which may not contain
 a full pathname) where possible $^X is now set by
           asking the operating system.  (eg by reading
           /proc/self/exe on Linux, /proc/curproc/file on
           FreeBSD)

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

       o   You can now override the readline() builtin, and this
           overrides also the <FILEHANDLE> angle bracket operator.


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

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

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

           Use of "/g" with "split" elicits "Use of /g modifier
           is meaningless in split".

       o   Support for the "CLONE" special subroutine had been
           added.  With ithreads, when a new thread is created,
           all Perl data is cloned, however non-Perl data cannot
           be cloned automatically.  In "CLONE" you can do whatever
 you need to do, like for example handle the
           cloning of non-Perl data, if necessary.  "CLONE" will
           be executed once for every package that has it defined
           or inherited.  It will be called in the context of the
           new thread, so all modifications are made in the new
           area.

           See perlmod

Modules and Pragmata    [Toc]    [Back]

       New Modules and Pragmata


       o   "Attribute::Handlers", originally by Damian Conway and
           now maintained by Arthur Bergman, allows a class to
           define attribute handlers.

               package MyPack;
               use Attribute::Handlers;
               sub Wolf :ATTR(SCALAR) { print "howl!0 }

               # later, in some package using or inheriting  from
MyPack...

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

           Both variables and routines can have attribute handlers.
  Handlers can be specific to type (SCALAR,
           ARRAY, HASH, or CODE), or specific to the exact compilation
 phase (BEGIN, CHECK, INIT, or END).  See
           Attribute::Handlers.

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

       o   The new bignum, bigint, and bigrat pragmas, by Tels,
           implement transparent bignum support (using the
           Math::BigInt, Math::BigFloat, and Math::BigRat backends).


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

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

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

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

       o   "Digest::MD5" for calculating MD5 digests (checksums)
           as defined in RFC 1321, from Gisle Aas, has been
           added.  See Digest::MD5.

               use Digest::MD5 'md5_hex';

               $digest = md5_hex("Thirsty Camel");

               print           $digest,           "0;           #
01d19d9d2045e005c3f1b80e8b164de1

           NOTE: the "MD5" backward compatibility module is
           deliberately not included since its further use is
           discouraged.

           See also PerlIO::via::QuotedPrint.

       o   "Encode", originally by Nick Ing-Simmons and now maintained
 by Dan Kogai, provides a mechanism to translate
           between different character encodings.  Support for
           Unicode, ISO-8859-1, and ASCII are compiled in to the
           module.  Several other encodings (like the rest of the
           ISO-8859, CP*/Win*, Mac, KOI8-R, three variants
           EBCDIC, Chinese, Japanese, and Korean encodings) are
           included and can be loaded at runtime.  (For space
           considerations, the largest Chinese encodings have
           been separated into their own CPAN module,
           Encode::HanExtra, which Encode will use if available).
           See Encode.

           Any encoding supported by Encode module is also available
 to the ":encoding()" layer if PerlIO is used.

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

       o   "I18N::Langinfo" can be used to query locale information.
  See I18N::Langinfo.

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

       o   "ExtUtils::Constant", by Nicholas Clark, is a new tool
           for extension writers for generating XS code to import
           C header constants.  See ExtUtils::Constant.
       o   "Filter::Simple", by Damian Conway, is an easy-to-use
           frontend to Filter::Util::Call.  See Filter::Simple.

               # in MyFilter.pm:

               package MyFilter;

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

               1;

               # in user's code:

               use MyFilter qr/red/ => 'green';

               print "red0;   # this code is filtered, will print
"green0
               print "bored0; # this code is filtered, will print
"bogreen0

               no MyFilter;

               print  "red0;    # this code is not filtered, will
print "red0

       o   "File::Temp", by Tim Jenness, allows one to create
           temporary files and directories in an easy, portable,
           and secure way.  See File::Temp.  [561+]

       o   "Filter::Util::Call", by Paul Marquess, provides you
           with the framework to write source filters in Perl.
           For most uses, the frontend Filter::Simple is to be
           preferred.  See Filter::Util::Call.

       o   "if", by Ilya Zakharevich, is a new pragma for conditional
 inclusion of modules.

       o   libnet, by Graham Barr, is a collection of perl5 modules
 related to network programming.  See Net::FTP,
           Net::NNTP, Net::Ping (not part of libnet, but
           related), Net::POP3, Net::SMTP, and Net::Time.

           Perl installation leaves libnet unconfigured; use lib-
           netcfg to configure it.

       o   "List::Util", by Graham Barr, is a selection of general-utility
 list subroutines, such as sum(), min(),
           first(), and shuffle().  See List::Util.

       o   "Locale::Constants", "Locale::Country", "Locale::Currency"
 "Locale::Language", and Locale::Script, by Neil
           Bowers, have been added.  They provide the codes for
           various locale standards, such as "fr" for France,
           "usd" for US Dollar, and "ja" for Japanese.

               use Locale::Country;

               $country  =  code2country('jp');                 #
$country gets 'Japan'
               $code      =  country2code('Norway');            #
$code gets 'no'

           See Locale::Constants, Locale::Country, Locale::Currency,
 and Locale::Language.

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

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

       o   "Memoize" can make your functions faster by trading
           space for time, from Mark-Jason Dominus.  See Memoize.

       o   "MIME::Base64", by Gisle Aas, allows you to encode
           data in base64, as defined in RFC 2045 - MIME (Multi-
           purpose Internet Mail Extensions).

               use MIME::Base64;

               $encoded = encode_base64('Aladdin:open sesame');
               $decoded = decode_base64($encoded);

               print   $encoded,   "0;   #    "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="

           See MIME::Base64.

       o   "MIME::QuotedPrint", by Gisle Aas, allows you to
           encode data in quoted-printable encoding, as defined
           in RFC 2045 - MIME (Multipurpose Internet Mail Exten-
           sions).

               use MIME::QuotedPrint;

               $encoded = encode_qp("");
               $decoded = decode_qp($encoded);

               print $encoded, "0; # "=DE=AD=BE=EF0
               print $decoded, "0; # "0

           See also PerlIO::via::QuotedPrint.

       o   "NEXT", by Damian Conway, is a pseudo-class for method
           redispatch.  See NEXT.
       o   "open" is a new pragma for setting the default I/O
           layers for open().

       o   "PerlIO::scalar", by Nick Ing-Simmons, provides the
           implementation of IO to "in memory" Perl scalars as
           discussed above.  It also serves as an example of a
           loadable PerlIO layer.  Other future possibilities
           include PerlIO::Array and PerlIO::Code.  See PerlIO::scalar.


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

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

               use PerlIO::via::QuotedPrint;
               open($fh,">:via(QuotedPrint)",$path);

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


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

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

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

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

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

       o   "Switch", by Damian Conway, has been added.  Just by
           saying

               use Switch;
           you have "switch" and "case" available in Perl.

               use Switch;

               switch ($val) {

                           case 1          { print "number 1" }
                           case "a"        { print "string a" }
                           case [1..10,42]  {  print  "number  in
list" }
                           case  (@array)    {  print  "number in
list" }
                           case /624
                           case qr/576
                           case  (%hash)     {  print  "entry  in
hash" }
                           case  (hash)   { print "entry in hash"
}
                           case (sub)    { print "arg to  subroutine" }
                           else            { print "previous case
not true" }
               }

           See Switch.

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

       o   "Test::Simple", by Michael Schwern, has basic utilities
 for writing tests.   See Test::Simple.

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

               use Text::Balanced 'extract_delimited';

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

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

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

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

       o   "threads::shared", by Arthur Bergman, allows data
           sharing for interpreter threads.  See threads::shared.
       o   "Tie::File", by Mark-Jason Dominus, associates a Perl
           array with the lines of a file.  See Tie::File.

       o   "Tie::Memoize", by Ilya Zakharevich, provides ondemand
 loaded hashes.  See Tie::Memoize.

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

       o   "Time::HiRes", by Douglas E. Wegscheid, provides high
           resolution timing (ualarm, usleep, and  gettimeofday).
           See Time::HiRes.

       o   "Unicode::UCD" offers a querying interface to the Unicode
 Character Database.  See Unicode::UCD.

       o   "Unicode::Collate", by SADAHIRO Tomoyuki, implements
           the UCA (Unicode Collation Algorithm) for sorting Unicode
 strings.  See Unicode::Collate.

       o   "Unicode::Normalize", by SADAHIRO Tomoyuki, implements
           the various Unicode normalization forms.  See Unicode::Normalize.


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

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

       Updated And Improved Modules and Pragmata    [Toc]    [Back]


       o   The following independently supported modules have
           been updated to the newest versions from CPAN: CGI,
           CPAN, DB_File, File::Spec, File::Temp, Getopt::Long,
           Math::BigFloat, Math::BigInt, the podlators bundle
           (Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser,
           Storable, Term::ANSIColor, Test, Text-Tabs+Wrap.

       o   attributes::reftype() now works on tied arguments.

       o   AutoLoader can now be disabled with "no  AutoLoader;".

       o   B::Deparse has been significantly enhanced by Robin
           Houston.  It can now deparse almost all of the standard
 test suite (so that the tests still succeed).
           There is a make target "test.deparse" for trying this
           out.
       o   Carp now has better interface documentation, and the
           @CARP_NOT interface has been added to get optional
           control over where errors are reported independently
           of @ISA, by Ben Tilly.

       o   Class::Struct can now define the classes in compile
           time.

       o   Class::Struct now assigns the array/hash element if
           the accessor is called with an array/hash element as
           the sole argument.

       o   The return value of Cwd::fastcwd() is now tainted.

       o   Data::Dumper now has an option to sort hashes.

       o   Data::Dumper now has an option to dump code references
           using B::Deparse.

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

       o   Devel::Peek now has an interface for the Perl memory
           statistics (this works only if you are using perl's
           malloc, and if you have compiled with debugging).

       o   The English module can now be used without the infamous
 performance hit by saying

                   use English '-no_match_vars';

           (Assuming, of course, that you don't need the troublesome
 variables $`, $&, or $'.)  Also, introduced
           @LAST_MATCH_START and @LAST_MATCH_END English aliases
           for "@-" and "@+".

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

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

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

       o   Fcntl, Socket, and Sys::Syslog have been rewritten by
           Nicholas Clark to use the new-style constant dispatch
           section (see ExtUtils::Constant).  This means that
           they will be more robust and hopefully faster.
       o   File::Find now chdir()s correctly when chasing symbolic
 links. [561]

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

       o   File::Find is now (again) reentrant.  It also has been
           made more portable.

       o   The warnings issued by File::Find now belong to their
           own category.  You can enable/disable them with
           "use/no warnings 'File::Find';".

       o   File::Glob::glob() has been renamed to
           File::Glob::bsd_glob() because the name clashes with
           the builtin glob().  The older name is still available
           for compatibility, but is deprecated. [561]

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

       o   IPC::Open3 now allows the use of numeric file descriptors.


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

       o   IO::Socket::INET failed to open the specified port if
           the service name was not known.  It now correctly uses
           the supplied port number as is. [561]

       o   IO::Socket::INET has support for the ReusePort option
           (if your platform supports it).  The Reuse option now
           has an alias, ReuseAddr.  For clarity, you may want to
           prefer ReuseAddr.

       o   IO::Socket::INET now supports a value of zero for
           "LocalPort" (usually meaning that the operating system
           will make one up.)

       o   'use lib' now works identically to @INC.  Removing
           directories with 'no lib' now works.

       o   Math::BigFloat and Math::BigInt have undergone a full
           rewrite by Tels.  They are now magnitudes faster, and
           they support various bignum libraries such as GMP and
           PARI as their backends.

       o   Math::Complex handles inf, NaN etc., better.
       o   Net::Ping has been considerably enhanced by Rob Brown:
           multihoming is now supported, Win32 functionality is
           better, there is now time measuring functionality
           (optionally high-resolution using Time::HiRes), and
           there is now "external" protocol which uses
           Net::Ping::External module which runs your external
           ping utility and parses the output.  A version of
           Net::Ping::External is available in CPAN.

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

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

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

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

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

       o   The Shell module now has an OO interface.

       o   In Sys::Syslog there is now a failover mechanism that
           will go through alternative connection mechanisms
           until the message is successfully logged.

       o   The Test module has been significantly enhanced.

       o   Time::Local::timelocal() does not handle fractional
           seconds anymore.  The rationale is that neither does
           localtime(), and timelocal() and localtime() are supposed
 to be inverses of each other.

       o   The vars pragma now supports declaring fully qualified
           variables.  (Something that "our()" does not and will
           not support.)

       o   The "utf8::" name space (as in the pragma) provides
           various Perl-callable functions to provide low level
           access to Perl's internal Unicode representation.  At
           the moment only length() has been implemented.

Utility Changes    [Toc]    [Back]

       o   Emacs perl mode (emacs/cperl-mode.el) has been updated
           to version 4.31.

       o   emacs/e2ctags.pl is now much faster.

       o   "enc2xs" is a tool for people adding their own encodings
 to the Encode module.

       o   "h2ph" now supports C trigraphs.

       o   "h2xs" now produces a template README.

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

       o   "h2xs" uses the new ExtUtils::Constant module which
           will affect newly created extensions that define constants.
  Since the new code is more cor

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