*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->OpenBSD man pages -> perl561delta (1)              



NAME    [Toc]    [Back]

       perl561delta - what's new for perl v5.6.x

DESCRIPTION    [Toc]    [Back]

       This document describes differences between the 5.005
       release and the 5.6.1 release.

Summary of changes between 5.6.0 and 5.6.1    [Toc]    [Back]

       This section contains a summary of the changes between the
       5.6.0 release and the 5.6.1 release.  More details about
       the changes mentioned here may be found in the Changes
       files that accompany the Perl source distribution.  See
       perlhack for pointers to online resources where you can
       inspect the individual patches described by these changes.

       Security Issues    [Toc]    [Back]

       suidperl will not run /bin/mail anymore, because some
       platforms have a /bin/mail that is vulnerable to buffer
       overflow attacks.

       Note that suidperl is neither built nor installed by
       default in any recent version of perl.  Use of suidperl is
       highly discouraged.  If you think you need it, try alternatives
 such as sudo first.  See http://www.courte-
       san.com/sudo/ .

       Core bug fixes    [Toc]    [Back]

       This is not an exhaustive list.  It is intended to cover
       only the significant user-visible changes.

           A bug in the caching mechanism used by "UNIVERSAL::isa()"
 that affected base.pm has been fixed.  The
           bug has existed since the 5.005 releases, but wasn't
           tickled by base.pm in those releases.

       Memory leaks
           Various cases of memory leaks and attempts to access
           uninitialized memory have been cured.  See "Known
           Problems" below for further issues.

       Numeric conversions
           Numeric conversions did not recognize changes in the
           string value properly in certain circumstances.

           In other situations, large unsigned numbers (those
           above 2**31) could sometimes lose their unsignedness,
           causing bogus results in arithmetic operations.

           Integer modulus on large unsigned integers sometimes
           returned incorrect values.
           Perl 5.6.0 generated "not a number" warnings on certain
 conversions where previous versions didn't.

           These problems have all been rectified.

           Infinity is now recognized as a number.

           In Perl 5.6.0, qw(a\b) produced a string with two
           backslashes instead of one, in a departure from the
           behavior in previous versions.  The older behavior has
           been reinstated.

           caller() could cause core dumps in certain situations.
           Carp was sometimes affected by this problem.

       Bugs in regular expressions
           Pattern matches on overloaded values are now handled

           Perl 5.6.0 parsed m/b}/ incorrectly, leading to
           spurious warnings.  This has been corrected.

           The RE engine found in Perl 5.6.0 accidentally pessimised
 certain kinds of simple pattern matches.
           These are now handled better.

           Regular expression debug output (whether through "use
           re 'debug'" or via "-Dr") now looks better.

           Multi-line    matches    like    ""a0b0    =~    /(?!0
flawed.  The bug has been fixed.

           Use of $& could trigger a core dump under some situations.
  This is now avoided.

           Match variables $1 et al., weren't being unset when a
           pattern match was backtracking, and the anomaly showed
           up inside "/...(?{ ... }).../" etc.  These variables
           are now tracked correctly.

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

       "slurp" mode
           readline() on files opened in "slurp" mode could
           return an extra "" at the end in certain situations.
           This has been corrected.

       Autovivification of symbolic references to special variables

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

       Lexical warnings
           Lexical warnings now propagate correctly into "eval

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

           Lexical warnings could leak into other scopes in some
           situations.  This is now fixed.

           warnings::enabled() now reports the state of $^W correctly
 if the caller isn't using lexical warnings.

       Spurious warnings and errors
           Perl 5.6.0 could emit spurious warnings about redefinition
 of dl_error() when statically building extensions
 into perl.  This has been corrected.

           "our" variables could result in bogus "Variable will
           not stay shared" warnings.  This is now fixed.

           "our" variables of the same name declared in two sibling
 blocks resulted in bogus warnings about "redeclaration"
 of the variables.  The problem has been corrected.

           Compatibility of the builtin glob() with old csh-based
           glob has been improved with the addition of
           GLOB_ALPHASORT option.  See "File::Glob".

           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.

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

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

           The tainting behavior of sprintf() has been rationalized.
  It does not taint the result of floating point
           formats anymore, making the behavior consistent with
           that of string interpolation.

           Arguments to sort() weren't being provided the right
           wantarray() context.  The comparison block is now run
           in scalar context, and the arguments to be sorted are
           always provided list context.

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

       #line directives
           #line directives now work correctly when they appear
           at the very beginning of "eval "..."".

       Subroutine prototypes
           The () prototype now works properly.

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

           Debugger  exit code now reflects the script exit code.

           Condition "0" in breakpoints is now treated correctly.

           The "d" command now checks the line number.

           $. is no longer corrupted by the debugger.

           All debugger output now correctly goes to the socket
           if RemotePort is set.

           PERL5OPT can be set to more than one switch group.
           Previously, it used to be limited to one group of
           options only.

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

       Unicode support
           Unicode support has seen a large number of incremental
           improvements, but continues to be highly experimental.
           It is not expected to be fully supported in the 5.6.x
           maintenance releases.

           substr(), join(), repeat(), reverse(), quotemeta() and
           string concatenation were all handling Unicode strings
           incorrectly in Perl 5.6.0.  This has been corrected.

           Support for "tr///CU" and "tr///UC" etc., have been
           removed since we realized the interface is broken.
           For similar functionality, see "pack" in perlfunc.
           The Unicode Character Database has been updated to
           version 3.0.1 with additions made available to the
           public as of August 30, 2000.

           The      Unicode     character     classes     {Blank}
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.)

           If you are experimenting with Unicode support in perl,
           the development versions of Perl may have more to
           offer.  In particular, I/O layers are now available in
           the development track, but not in the maintenance
           track,  primarily to do backward compatibility issues.
           Unicode support is also evolving rapidly on a daily
           basis in the development track--the maintenance track
           only reflects the most conservative of these  changes.

       64-bit support
           Support for 64-bit platforms has been improved, but
           continues to be experimental.  The level of support
           varies greatly among platforms.

           The B Compiler and its various backends have had many
           incremental improvements, but they continue to remain
           highly experimental.  Use in production environments
           is discouraged.

           The perlcc tool has been rewritten so that the user
           interface is much more like that of a C compiler.

           The perlbc tools has been removed.  Use "perlcc -B"

       Lvalue subroutines
           There have been various bugfixes to support lvalue
           subroutines better.  However, the feature still
           remains experimental.

           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.

           File::Find now chdir()s correctly when chasing symbolic

           xsubpp now tolerates embedded POD sections.
       "no Module;"
           "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".

           A large number of tests have been added.

       Core features    [Toc]    [Back]

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

       The "-DT" command line switch outputs copious tokenizing
       information.  See perlrun.

       Arrays are now always interpolated in double-quotish
       strings.  Previously, "foo@bar.com" used to be a fatal
       error at compile time, if an array @bar was not used or
       declared.  This transitional behavior was intended to help
       migrate  perl4 code, and is deemed to be no longer useful.
       See "Arrays now always interpolate into double-quoted

       keys(), each(), pop(), push(), shift(), splice() and
       unshift() can all be overridden now.

       "my __PACKAGE__ $obj" now does the expected thing.

       Configuration issues    [Toc]    [Back]

       On some systems (IRIX and Solaris among them) the system
       malloc is demonstrably better.  While the defaults haven't
       been changed in order to retain binary compatibility with
       earlier releases, you may be better off building perl with
       "Configure -Uusemymalloc ..." as discussed in the INSTALL

       "Configure" has been enhanced in various ways:

       o   Minimizes use of temporary files.

       o   By default, does not link perl with libraries not used
           by it, such as the various dbm libraries.  SunOS 4.x
           hints preserve behavior on that platform.

       o   Support for pdp11-style memory models has been removed
           due to obsolescence.

       o   Building outside the source tree is supported on systems
 that have symbolic links. This is done by running

               sh /path/to/source/Configure -Dmksymlinks ...
               make all test install
           in a directory other than the perl source directory.
           See INSTALL.

       o   "Configure -S" can be run non-interactively.

       Documentation    [Toc]    [Back]

       README.aix, README.solaris and README.macos have been
       added.  README.posix-bc has been renamed to README.bs2000.
       These are installed as perlaix, perlsolaris, perlmacos,
       and perlbs2000 respectively.

       The following pod documents are brand new:

           perlclib    Internal replacements for standard  C  library functions
           perldebtut  Perl debugging tutorial
           perlebcdic   Considerations for running Perl on EBCDIC
           perlnewmod  Perl modules: preparing a new  module  for
           perlrequick Perl regular expressions quick start
           perlretut   Perl regular expressions tutorial
           perlutil    utilities packaged with the Perl distribution

       The INSTALL file has been expanded to cover various
       issues, such as 64-bit support.

       A longer list of contributors has been added to the source
       distribution.  See the file "AUTHORS".

       Numerous other changes have been made to the included documentation
 and FAQs.

       Bundled modules    [Toc]    [Back]

       The following modules have been added.

           Walks Perl syntax tree, printing concise info about
           ops.  See B::Concise.

           Returns name and handle of a temporary file safely.
           See File::Temp.

           Converts Pod data to formatted LaTeX.  See Pod::LaTeX.

           Converts POD data to formatted overstrike text.  See

       The following modules have been upgraded.

       CGI CGI v2.752 is now included.
           CPAN v1.59_54 is now included.

           Various bugfixes have been added.

           DB_File v1.75 supports newer Berkeley DB versions,
           among other improvements.

           Devel::Peek has been enhanced to support dumping of
           memory statistics, when perl is built with the
           included malloc().

           File::Find now supports pre and post-processing of the
           files in order to sort() them, etc.

           Getopt::Long v2.25 is included.

           Various bug fixes have been included.

           IPC::Open3 allows use of numeric file descriptors.

           The fmod() function supports modulus operations.  Various
 bug fixes have also been included.

           Math::Complex handles inf, NaN etc., better.

           ping() could fail on odd number of data bytes, and
           when the echo service isn't running.  This has been

           A memory leak has been fixed.

           Version 1.13 of the Pod::Parser suite is included.

           Pod::Text and related modules have been upgraded to
           the versions in podlators suite v2.08.

           On dosish platforms, some keys went missing because of
           lack of support for files with "holes".  A workaround
           for the problem has been added.
           Various bug fixes have been included.

           Now supports Tie::RefHash::Nestable to automagically
           tie hashref values.

           Various bug fixes have been included.

       Platform-specific improvements    [Toc]    [Back]

       The following new ports are now available.

       NCR MP-RAS

       Perl now builds under Amdahl UTS.

       Perl has also been verified to build under Amiga OS.

       Support for EPOC has been much improved.  See README.epoc.

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

       Long doubles should now work under Linux.

       Mac OS Classic is now supported in the mainstream source
       package.  See README.macos.

       Support for MPE/iX has been updated.  See README.mpeix.

       Support for OS/2 has been improved.  See "os2/Changes" and

       Dynamic loading on z/OS (formerly OS/390) has been
       improved.  See README.os390.

       Support for VMS has seen many incremental improvements,
       including better support for operators like backticks and
       system(), and better %ENV handling.  See "README.vms" and

       Support for Stratus VOS has been improved.  See
       "vos/Changes" and README.vos.

       Support for Windows has been improved.

       o   fork() emulation has been improved in various ways,
           but still continues to be experimental.  See perlfork
           for known bugs and caveats.
       o   %SIG has been enabled under USE_ITHREADS, but its use
           is completely unsupported under all configurations.

       o   Borland C++ v5.5 is now a supported compiler that can
           build Perl.  However, the generated binaries continue
           to be incompatible with those generated by the other
           supported compilers (GCC and Visual C++).

       o   Non-blocking waits for child processes (or pseudo-processes)
 are supported via "waitpid($pid, &POSIX::WNOHANG)".

       o   A memory leak in accept() has been fixed.

       o   wait(), waitpid() and backticks now return the correct
           exit status under Windows 9x.

       o   Trailing new %ENV entries weren't propagated to child
           processes.  This is now fixed.

       o   Current directory entries in %ENV are now correctly
           propagated to child processes.

       o   Duping socket handles with open(F, ">&MYSOCK") now
           works under Windows 9x.

       o   The makefiles now provide a single switch to bulkenable
 all the features enabled in ActiveState
           ActivePerl (a popular binary distribution).

       o   Win32::GetCwd() correctly returns C: instead of C:
           when at the drive root.  Other bugs in chdir() and
           Cwd::cwd() have also been fixed.

       o   fork() correctly returns undef and sets EAGAIN when it
           runs out of pseudo-process handles.

       o   ExtUtils::MakeMaker now uses $ENV{LIB} to search for

       o   UNC path handling is better when perl is built to support

       o   A handle leak in socket handling has been fixed.

       o   send() works from within a pseudo-process.

       Unless specifically qualified otherwise, the remainder of
       this document covers changes between the 5.005 and 5.6.0

Core Enhancements    [Toc]    [Back]

       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 subroutine in a separate interpreter
 and run the cloned subroutine in a separate 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

       -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
       interpreter, and is therefore copied for each clone.

       Note that building Perl with the -Dusemultiplicity Configure
 option is adequate if you wish to run multiple inde-
       pendent interpreters concurrently in different threads.
       -Dusethreads only provides the additional functionality of
       the perl_clone() API call and other support for running
       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    [Toc]    [Back]

       Perl now uses UTF-8 as its internal representation for
       character strings.  The "utf8" and "bytes" pragmas are
       used to control this support 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 Unicode.

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

       Support for interpolating named characters    [Toc]    [Back]

       The new "scape interpolates named characters within
       strings.  For example, "Hi! HITE SMILING FACE}" evaluates
 to a string with a Unicode 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 useful as an alternative
 to the "vars" pragma, but also provides the opportunity
 to introduce typing and other attributes for such
       variables.  See "our" in perlfunc.

       Support for strings represented as a vector of ordinals    [Toc]    [Back]

       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 interpolating characters,
       as in "".  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 "numbers".  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 you're 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 literals.  They will be interpreted as a version
       rather than as a module name:

           require v5.6.0;             # croak if $^V lt v5.6.0
           use v5.6.0;                 # same, but croaks at compile-time

       Alternatively, the "v" may be omitted if there is more
       than one dot:

           require 5.6.0;
           use 5.6.0;

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

           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

       Improved Perl version numbering system    [Toc]    [Back]

       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

       The English module now sets $PERL_VERSION to $^V (a string
       value) rather than $] (a numeric value).  (This is a
       potential incompatibility.  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 system's use of at least
       three significant digits for each version component, the
       method used for incrementing the subversion number has
       also changed slightly.  We assume that versions older than
       v5.6.0 have been incrementing the subversion component 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    [Toc]    [Back]

       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

       File and directory handles can be autovivified    [Toc]    [Back]

       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 variable.  This allows the
       constructs such as "open(my $fh, ...)" and "open(local
       $fh,...)"  to be used to create filehandles that will conveniently
 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

           sub myopen {
               open my $fh, "@_"
                    or die "Can't open '@_': $!";
               return $fh;

               my $f = myopen("</etc/motd");
               print <$f>;
               # $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:

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

       o   arguments to oct() and hex()

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

       o   printed as such

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

       o   in basic arithmetics: + - * / % (NOTE: operating close
           to the limits of the integer values may produce surprising

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

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

           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 integers 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 doesn't 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 integers (if it can), longs (and pointers) to being
       64-bit.  This may create 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 aware.

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

       Last but not least: note that due to Perl's 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,
       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
           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    [Toc]    [Back]

       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 Perl.
           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_LARGEFILE, 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 shell's 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    [Toc]    [Back]

       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, Perl's numbers).  Use
       Configure -Duselongdouble to enable this support (if it is

       "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 perlfunc.

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

       "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    [Toc]    [Back]

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

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

       Support for CHECK blocks    [Toc]    [Back]

       In addition to "BEGIN", "INIT", "END", "DESTROY" and
       "AUTOLOAD", subroutines 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 cannot
       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    [Toc]    [Back]

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

       These changes should result in better random numbers from

       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 "$foo|$bar0;

       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 sequences.

       pack() format 'Z' supported

       The new format type 'Z' is useful for packing and unpacking
 null-terminated 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

       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()

       Weak references    [Toc]    [Back]

       In previous versions of Perl, you couldn't 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 "oct()":

           $answer = 0b101010;
           printf "The answer is: %b0, oct("0b101010");

       Lvalue subroutines    [Toc]    [Back]

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

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

       Some arrows may be omitted in calls through references    [Toc]    [Back]

       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

       Boolean assignment operators are legal lvalues    [Toc]    [Back]

       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

       exists() can be used to check whether an array element has
       been initialized.  This avoids autovivifying array elements
 that don't exist.  If the array is tied, the
       EXISTS() method in the corresponding tied package will be

       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

       Pseudo-hashes work better    [Toc]    [Back]

       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 pseudohash
 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 perlref.

       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

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

       Automatic flushing of output buffers    [Toc]    [Back]

       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) isn't

       Better diagnostics on meaningless filehandle operations    [Toc]    [Back]

       Constructs such as "open(<FH>)" and "close(<FH>)" 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 filehandles does).
       Where possible, buffered data discarded from duped input

       "open(NEW, "<&OLD")" now attempts to discard any data that
       was previously read and buffered in "OLD" before duping
       the handle.  On platforms 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 following
       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 pseudodisciplines
 ":raw" and ":crlf" are currently supported on
       DOS-derivative platforms.  See "binmode" in perlfunc and

       "-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() fail-

       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    [Toc]    [Back]

       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 constructs 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

       Diagnostics  that occur within eval may also report the
       file and line number where the eval is located, in addition
 to the eval sequence number 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    [Toc]    [Back]

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

       More consistent close-on-exec behavior    [Toc]    [Back]

       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 $^F that may be in effect.  Earlier
 versions neglected to set the flag for handles created
 with these operators.  See "pipe" in perlfunc, "socketpair"
 in perlfunc, "socket" in perlfunc, "accept" in
       perlfunc, and "$^F" in perlvar.

       syswrite() ease-of-use

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

       Better syntax checks on parenthesized unary operators    [Toc]    [Back]

       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 argument, making the cases shown
       above syntax errors.  The usual behaviour of:

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

       remains unchanged.  See perlop.

       Bit operators support full native integer width    [Toc]    [Back]

       The bit operators (& | ^ ~ << >>) now operate on the full
       native integral 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    [Toc]    [Back]

       More potentially unsafe operations taint their results for
       improved security.

       The "passwd" and "shell" fields returned by the getp-
       went(), getpwnam(), and getpwuid() ar

 Similar pages
Name OS Title
perljp OpenBSD AEuEU,i Perl Y~YxYE `A^a`I`A Perl xIAx3|xOxex|x3x1/2! Perl 5.8.0 xexeicUni- _ codeYuYYi1/4YEx~AcEyxE...
perl572delta OpenBSD what's new for perl v5.7.2
perl56delta OpenBSD what's new for perl v5.6.0
perl585delta OpenBSD what is new for perl v5.8.5
perl570delta OpenBSD what's new for perl v5.7.0
perl571delta OpenBSD what's new for perl v5.7.1
perl573delta OpenBSD what's new for perl v5.7.3
perl584delta OpenBSD what is new for perl v5.8.4
perl581delta OpenBSD what is new for perl v5.8.1
perl582delta OpenBSD what is new for perl v5.8.2
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service