=head1 NAME
-perldelta - what's new for perl v5.7.0
+perldelta - what is new for perl v5.8.0
=head1 DESCRIPTION
-This document describes differences between the 5.6.0 release and
-the 5.7.0 release.
+This document describes differences between the 5.6.0 release
+and the 5.8.0 release.
-=head1 Security Vulnerability Closed
-
-A potential security vulnerability in the optional suidperl component
-of Perl has been identified. The suidperl is neither built nor
-installed by default. As of August the 20th, 2000, the only known
-vulnerable platform is Linux, most likely all Linux distributions.
-The CERT and various vendors have been alerted about the vulnerability.
-
-The problem was caused by Perl trying to report a suspected security
-exploit attempt using an external program, /bin/mail. In Linux
-platforms the /bin/mail program had an undocumented feature which gave
-access to a root shell, resulting in a serious compromise, instead of
-reporting the exploit attempt. If you don't have /bin/mail or if you
-have 'safe suid scripts' or if you haven't installed the suidperl, you
-are safe.
+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.
-The exploit attempt reporting feature has been completely removed from
-the Perl 5.7.0 release, so that particular vulnerability isn't there
-anymore. However, further security vulnerabilities are,
-unfortunately, always possible. The suidperl code is being reviewed
-and if deemed too risky to continue being supported, in the extreme
-case it may be completely removed in future releases. In any case,
-suidperl should only be used by security experts who know exactly what
-they are doing and why they are using suidperl instead of some other solution.
-A good tool for similar needs is sudo: http://www.courtesan.com/sudo/
+If you are upgrading from Perl 5.005_03, you might also want
+to read L<perl56delta>.
-=head1 Incompatible Changes
+=head1 Highlights In 5.8.0
-=head2 Arrays Now Always Interpolate Into Double-Quoted Strings
+=over 4
-Constructs like "foo@bar" now always assume the C<@bar> to be an array,
-regardless of whether it is known that C<@bar> is an array.
+=item *
-=head2 bless(REF, REF) is now a fatal error
+Better Unicode support
-The semantics of bless(REF, REF) were unclear and until someone proves
-it to make some sense, it is forbidden.
+=item *
-=head2 The eg/* Directory Removed
+New Thread Implementation
-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.
+=item *
-=head2 The lib/chat2.pl
+Many New Modules
-The obsolete chat2 library that should never have been allowed
-to escape the laboratory has been decommissioned.
+=item *
-=head2 Unimplemented (But Recognised) POSIX Regex Features Now Fatal
+Better Numeric Accuracy
-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.
+=item *
-=head2 lstat(FILEHANDLE) now warns
+Safe Signals
-lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
-In future releases this may become a fatal error.
+=item *
-=head2 Obsolete String Comparison Operators Removed
+More Extensive Regression Testing
-The long since deprecated uppercase aliases for the string comparison
-operators (EQ, NE, LT, LE, GE, GT) have now been removed.
+=back
-=head2 The Regular Expression Submatches Are Now Unset When Backtracking
+=head1 Incompatible Changes
-The regular expression captured submatches ($1, $2, ...) are now
-consistently unset if the match fails, instead of leaving false
-data lying around in them.
+=head2 64-bit platforms and malloc
-=head2 tr///CU Removed, Not To Return
+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 (like modperl) tend to prefer
+the system malloc. Such platforms include Alpha and 64-bit HPPA,
+MIPS, PPC, and Sparc.
-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', ...).
+=head2 AIX Dynaloading
-=head1 Core Enhancements
+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 modperl which are using the AIX native interface.
-=over 4
+=head2 Attributes for C<my> variables now handled at run-time.
-=item *
+The C<my EXPR : ATTRS> syntax now applies variable attributes at
+run-time. (Subroutine and C<our> variables still get attributes applied
+at compile-time.) See L<attributes> for additional details. In particular,
+however, this allows variable attributes to be useful for C<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).
-C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
-in multiple arguments.)
+=head2 Socket Extension Dynamic in VMS
-=item *
+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.
-my __PACKAGE__ now works.
+=head2 IEEE-format Floating Point Default on OpenVMS Alpha
-=item *
+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.
-no Module; now works even if there is no "sub unimport" in the Module.
+=head2 New Unicode Properties
-=item *
+Unicode I<scripts> are now supported. Scripts are similar to (and superior
+to) Unicode I<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.
-The numerical comparison operators return C<undef> if either operand
-is a NaN. Previously the behaviour was unspecified.
+In general, scripts are more inclusive, but not universally so. For
+example, while the script C<Latin> includes all the Latin characters and
+their various diacritic-adorned versions, it does not include the various
+punctuation or digits (since they are not solely C<Latin>).
-=item *
+A number of other properties are now supported, including C<\p{L&}>,
+C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> and
+C<\p{SpacePerl}> (along with their C<\P{...}> versions, of course).
+See L<perlunicode> for details, and more additions.
-C<pack('U0a*', ...)> can now be used to force a string to UTF8.
+The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}>
+are now almost always optional. The only exception is that a C<In> prefix
+is required to signify a Unicode block when a block name conflicts with a
+script name. For example, C<\p{Tibetan}> refers to the script, while
+C<\p{InTibetan}> refers to the block. When there is no name conflict, you
+can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but
+to be safe, it's probably best to always use the C<In>).
-=item *
+=head2 Perl Parser Stress Tested
-prototype(\&) is now available.
+The Perl parser has been stress tested using both random input and
+Markov chain input and the few found crashes and lockups have been
+fixed.
-=back
+=head2 REF(...) Instead Of SCALAR(...)
-=head1 Modules and Pragmata
+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().
-=head2 New Modules
+=head2 Deprecations
=over 4
=item *
-File::Temp, version 0.10, allows one to create temporary files
-and directories in an easy, portable, and secure way.
+The semantics of bless(REF, REF) were unclear and until someone proves
+it to make some sense, it is forbidden.
=item *
-The Storable extension, version 0.7.2, released the 14th of August
-2000, has been added to the Perl distribution. 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.
-
-=back
+The obsolete chat2 library that should never have been allowed
+to escape the laboratory has been decommissioned.
-=head2 Updated And Improved Modules and Pragmata
+=item *
-=over 4
+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 C<CORE::dump()>, but in future
+releases the behaviour of an unqualified C<dump()> call may change.
=item *
-The attributes::reftype() now works on tied arguments.
+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.
=item *
-AutoLoader can now be `stopped' by
-
- no AutoLoader;
+The (bogus) escape sequences \8 and \9 now give an optional warning
+("Unrecognized escape passed through"). There is no need to \-escape
+any C<\w> character.
=item *
-B::Deparse now understands sub attributes.
+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.)
=item *
-Data::Dumper now works on negative number on 32-bit platforms where IV
-(the Perl's integer datatype) is greater than 32 bits. Also, large
-unsigned numbers are now dumped as such, not as large negative numbers.
+Spurious syntax errors generated in certain situations, when glob()
+caused File::Glob to be loaded for the first time, have been fixed.
=item *
-CGI has been updated to version 2.72, released
-the 20th of August 2000.
+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 L</"Performance Enhancements">.
=item *
-CPAN has been updated to version 1.57, released
-the 16th of August 2000.
+lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
+In future releases this may become a fatal error.
=item *
-DB_File has been updated to version 1.73, released the
-27th of April 2000.
+The C<package;> syntax (C<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, C<use strict;> instead.
=item *
-The English module can now be used without the infamous performance
-hit by saying
+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.
- use English '-no_performance_hit';
+=item *
-(Assuming, of course, that one doesn't need the troublesome variables
-C<$`>, C<$&>, or C<$'>.) Also, introduce C<@LAST_MATCH_START> and
-C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
+The current user-visible implementation of pseudo-hashes (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 C<fields> pragma interface will remain
+available.
=item *
-File::Find now has pre- and postprocessing callbacks.
-It also correctly changes directories when chasing symbolic links.
-Callbacks doing (naughtily) "next;" instead of "return;" now work.
+The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
=item *
-File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
-prototype mismatch with CORE::glob().
+After years of trying the 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.
=item *
-File::Spec has been updated to version 0.82, released the
-1st of July 2000.
+The long deprecated uppercase aliases for the string comparison
+operators (EQ, NE, LT, LE, GE, GT) have now been removed.
=item *
-Getopt::Long has been updated to version 2.23_05, released the 2nd of
-August 2000.
+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', ...).
=item *
-IO::Poll has been thoroughly fixed.
+Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
+The prototypes are now checked at compile-time for invalid characters.
+An optional warning is generated ("Illegal character in prototype...")
+but this may be upgraded to a fatal error in a future release.
-=item *
+=back
-IO::Socket::INET now works when given an unknown service name with
-a port number.
+=head1 Core Enhancements
-=item *
+=head2 PerlIO is Now The Default
-IPC::Open3 now allows the use of numeric file descriptors.
+=over 4
=item *
-use lib now works identically to @INC. Removing directories
-with 'no lib' now works.
+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:
-=item *
+ open($fh,'>:crlf :utf8', $path) || ...
-Math::BigFloat now more robust (fewer "uninitialized" warnings).
+or on already opened handles via extended C<binmode>:
-=item *
+ binmode($fh,':encoding(iso-8859-7)');
-Math::Complex now handles extreme values (e.g. cplx(1E20, 1E30)) more
-gracefully.
+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 <=> "\n" translation as on Win32,
+but available on any platform). A mmap layer may be available if
+platform supports it (mostly UNIXes).
-=item *
+Layers to be applied by default may be specified via the 'open' pragma.
-The podlators bundle has been updated to version 1.02, released the
-25th of April 2000. It contains the modules Pod::Man 1.04, Pod::Text
-2.04, and modules Pod::Text::Color and Pod::Text::Termcap (no version
-numbers).
+See L</"Installation and Configuration Improvements"> for the effects
+of PerlIO on your architecture name.
=item *
-Pod::LaTeX has been updated to version 0.52, released the 15th of May
-2000. Note that this is a complete rewrite which translates pod much
-better, has many more options and much better documentation. It also
-now uses the Pod::Parser backend, meaning that Pod::LaTeX will stay
-abreast other pod translators.
+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" :
-=item *
+ open($fh,">:utf8","Uni.txt");
-Pod::Parser has been updated to version 1.17, released the 25th of
-July 2000. It contains the modules Pod::Checker 1.20, Pod::Find 0.21,
-Pod::InputObjects 1.13, Pod::ParseUtils 0.22, Pod::Parser 1.12,
-Pod::Select 1.13, and Pod::Usage 1.13.
+Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
+for you since it's not UTF-8 what you will be getting but instead
+UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
+http://www.unicode.org/unicode/reports/tr16/ for more information.
+In future releases this naming may change.
=item *
-The 'debug' subpragma the 're' pragma now produces cleaner output.
+File handles can translate character encodings from/to Perl's internal
+Unicode form on read/write via the ":encoding()" layer.
=item *
-C<%INC> now localised in a Safe compartment so that use/require work.
+File handles can be opened to "in memory" files held in Perl scalars via:
+
+ open($fh,'>', \$variable) || ...
=item *
-SelfLoader no longer loses C<$@> in AUTOLOAD.
+Anonymous temporary files are available without need to
+'use FileHandle' or other module via
-=item *
+ open($fh,"+>", undef) || ...
-The Shell module now has an OO interface.
+That is a literal undef, not an undefined value.
=item *
-Sys::Syslog now works on domain sockets. Also, a forked child
-now exits correctly if it fails to open /dev/console.
+The list form of C<open> is now implemented for pipes (at least on UNIX):
-=item *
+ open($fh,"-|", 'cat', '/etc/motd')
-Term::ANSIColor has been updated to version 1.03, released the 6th of
-August 2000.
+creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
+the child process.
-=item *
+=back
-The Test module has been updated to version 1.14, released the 21st of June
-1999. This is for all practical purposes identical to the previous release
-of Test included with the Perl distribution, 1.13, but upgrading the module
-stops the CPAN module from suggesting an upgrade.
+=head2 Safe Signals
-=item *
+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).
-Test::Harness output now prettier on failed test.
+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.
-=item *
+=head2 Unicode Overhaul
-Text::Wrap::wtbrap now handles multiline strings properly.
+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.
-=item *
+=over 4
-UNIVERSAL::isa no longer caches methods incorrectly.
+=item *
-=back
+The Unicode Character Database coming with Perl has been upgraded
+to Unicode 3.1.1. For more information, see http://www.unicode.org/.
-=head1 Utility Changes
+=item *
-=head2 cperl-mode version 4.31
+For developers interested in enhancing Perl's Unicode capabilities:
+almost all the UCD files are included with the Perl distribution in
+the F<lib/unicore subdirectory>. The most notable omission, for space
+considerations, is the Unihan database.
-The Emacs perl mode (emacs/cperl-mode.el) has been updated to version 4.31.
+=item *
-=head2 perlbug
+The properties \p{Blank} and \p{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 C<\s> (\p{Space} isn't, since that includes the vertical
+tabulator character, whereas C<\s> doesn't.)
-Perlbug is now much more robust. It also sends the bug report to perl.org,
-not perl.com.
+See "New Unicode Properties" earlier in this document for additional
+information on changes with Unicode properties.
-=head2 perlcc now more cc-like and more robust
+=back
-The perlcc utility has been rewritten and its user interface (that is,
-command line) is much more like that of the UNIX C compiler, cc.
+=head2 Understanding of Numbers
-=head2 xsubpp now understands embedded pod
+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 C<strtoul()>
+and C<atof()> seem to have bugs, Perl tries to work around their
+deficiencies. This results hopefully in more accurate numbers.
-The xsubpp utility for extension writers now understands POD
-documentation embedded in the *.xs files.
+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.)
-=head1 Improved Documentation
+=head2 Miscellaneous Changes
=over 4
=item *
-In many places say "alphanumeric characters" instead of "word
-characters" because that was what was meant.
+AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
+to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
=item *
-Eradicate "array context" from the documentation and diagnostics.
+C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
+in multiple arguments.)
=item *
-The return values of failing backticks (`, qx{}) are now documented
-in perlop.
+The builtin dump() now gives an optional warning
+C<Ambiguous call resolved as CORE::dump(), qualify as such or use &>
+meaning that by default C<dump(...)> is resolved as the builtin
+dump() which dumps core and aborts, not as (possibly) user-defined
+C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
+(The whole dump() feature is to considered deprecated, and possibly
+removed/changed in future releases.)
=item *
-caller() return values now better documented.
+chomp() and chop() have been demoted back to I<not> being overrideable
+because they cannot really be overridden-- the problem is that their
+prototype cannot be expressed and therefore one really cannot write
+replacements to override these builtins.
=item *
-SDBM_File, NDBM_File, ODBM_File, now tell about tying instead of
-glossing over.
+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
+L<perlembed>.
=item *
-Document that the C<$(> special variable does not interpolate
-in regular expressions.
+Formats now support zero-padded decimal fields.
=item *
-The timeout unit of IO::Select is now documented to be identical
-to the timeout unit of the 4-arg select(), that is, (optionally
-fractional) seconds, or an undef to wait indefinitely.
+Lvalue subroutines can now return C<undef> in list context.
+However, the lvalue subroutine feature still remains experimental.
=item *
-Document the C<D> and C<d> magic types.
+A lost warning "Can't declare ... dereference in my" has been
+restored (Perl had it earlier but it became lost in later releases.)
=item *
-The ordering of PODs in perl.pod is now more sensible.
+A new special regular expression variable has been introduced:
+C<$^N>, which contains the most-recently closed group (submatch).
=item *
-perlbook now only mentions the Camel III; all other book references
-have been moved to perlfaq2; some good known books added.
+C<no Module;> now works even if there is no "sub unimport" in the Module.
=item *
-Numerous missing warning/error messages added to perldiag.
+The numerical comparison operators return C<undef> if either operand
+is a NaN. Previously the behaviour was unspecified.
=item *
-Changed the description of perl6 in perlfaq1.
+The following builtin functions are now overridable: each(), keys(),
+pop(), push(), shift(), splice(), unshift().
=item *
-perlhack much extended.
+C<pack('U0a*', ...)> can now be used to force a string to UTF8.
=item *
-perltrap cleaned up.
+my __PACKAGE__ $obj now works.
=item *
-Add perlxstut example for passing/returning refs to arrays.
+The printf() and sprintf() now support parameter reordering using the
+C<%\d+\$> and C<*\d+\$> syntaxes. For example
-=item *
+ print "%2\$s %1\$s\n", "foo", "bar";
-POSIX module documentation embellished.
+will print "bar foo\n". This feature helps in writing
+internationalised software, and in general when the order
+of the parameters can vary.
=item *
-Clarified the status of shadow password support.
+prototype(\&) is now available.
=item *
-Reminded that preprocessors and source filters can alter
-your code before Perl sees it and therefore debugging
-can be somewhat surprising. ("I didn't write *that*!")
+prototype(\[$@%&]) is now available to implicitly create references
+(useful for example if you want to emulate the tie() interface).
=item *
-Removed incorrect documentation about implicit split to @_
-in list context, which never really worked in Perl 5 anyway.
+A new command-line option, C<-t> is available. It is the
+little brother of C<-T>: instead of dieing on taint violations,
+lexical warnings are given. B<This is only meant as a temporary
+debugging aid while securing the code of old legacy applications.
+This is not a substitute for -T.>
=item *
-Explain that split /^/ is split /^/m.
+If tr/// is just counting characters, it doesn't attempt to
+modify its target.
=item *
-Added many more sprintf() examples in perlfunc.
+untie() will now call an UNTIE() hook if it exists. See L<perltie>
+for details.
=item *
-Documented the handling of negative indices to tied arrays.
+L<utime> now supports C<utime undef, undef, @files> to change the
+file timestamps to the current time.
=item *
-The C<$yday> in localtime()/gmtime() is 0..364, not 1..365.
+The rules for allowing underscores (underbars) in numeric constants
+have been relaxed and simplified: now you can have an underscore
+simply B<between digits>.
-=item *
+=back
-Documented that tr() is not tr(1): that is, do not expect regular expressions.
+=head1 Modules and Pragmata
-=item *
+=head2 New Modules and Pragmata
-Warn about the vagaries of UDP.
+=over 4
=item *
-The "uninitialized variable" warnings now say "concat or string" or
-"join or string" instead of just "concat" or "join" since many users
-found the "concat" a bit surprising when they were doing "just"
-variable interpolation.
-
-=item *
+C<Attribute::Handlers> allows a class to define attribute handlers.
-Documented that the values() are aliases, not copies.
+ package MyPack;
+ use Attribute::Handlers;
+ sub Wolf :ATTR(SCALAR) { print "howl!\n" }
-=back
+ # later, in some package using or inheriting from MyPack...
-=head2 New Documentation
+ my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
-=over 4
+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).
=item *
-perl56delta details the changes between the 5.005 release and the
-5.6.0 release.
+B<B::Concise> is a new compiler backend for walking the Perl syntax
+tree, printing concise info about ops, from Stephen McCamant. The
+output is highly customisable. See L<B::Concise>.
=item *
-perldebtut is a Perl debugging tutorial.
+C<Class::ISA> for reporting the search path for a class's ISA tree,
+by Sean Burke, has been added. See L<Class::ISA>.
=item *
-perlebcdic contains considerations for running Perl on EBCDIC platforms.
-Note that unfortunately EBCDIC platforms that used to supported back in
-Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
-bring them back to the fold.
+C<Cwd> has now 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.
=item *
-perlnewmod tells about writing and submitting a new module.
+C<Devel::PPPort>, originally from Kenneth Albanowski and now
+maintained by Paul Marquess, has been added. It is primarily used
+by C<h2xs> to enhance portability of of XS modules between different
+versions of Perl.
=item *
-perlposix-bc explains using Perl on the POSIX-BC platform
-(a mainframe platform).
+C<Digest>, frontend module for calculating digests (checksums), from
+Gisle Aas, has been added. See L<Digest>.
=item *
-perlretut is a regular expression tutorial.
+C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
+RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
-=item *
+ use Digest::MD5 'md5_hex';
-perlrequick is a regular expressions quick-start guide.
-Yes, much quicker than perlretut.
+ $digest = md5_hex("Thirsty Camel");
-=item *
+ print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
-perlutil explains the command line utilities packaged with the Perl
-distribution.
+NOTE: the C<MD5> backward compatibility module is deliberately not
+included since its further use is discouraged.
-=back
+=item *
-=head1 Performance Enhancements
+C<Encode>, by Nick Ing-Simmons, provides a mechanism to translate
+between different character encodings. Support for Unicode,
+ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
+compiled in to the module. Several other encodings (like Japanese,
+Chinese, and MacIntosh encodings) are included and will be loaded at
+runtime. See L<Encode>.
-map() that changes the size of the list should now work faster.
+Any encoding supported by Encode module is also available to the
+":encoding()" layer if PerlIO is used.
-=head1 Installation and Configuration Improvements
+=item *
-=head2 INSTALL now explains 64-bit configuration.
+C<I18N::Langinfo> can be use to query locale information.
+See L<I18N::Langinfo>.
-In some platforms Perl can be configured to use 64-bit integers,
-allowing 4 billion times better... sorry, switched accidentally
-to marketdroid mode for a moment in there. (In platforms which
-are natively 64-bit this makes no difference.)
+=item *
-=head2 Policy.sh policy change
+C<I18N::LangTags> has functions for dealing with RFC3066-style
+language tags, by Sean Burke. See L<I18N::LangTags>.
-If you are reusing a Policy.sh file (see INSTALL) and you use
-Configure -Dprefix=/foo/bar and in the old Policy $prefix eq
-$siteprefix and $prefix eq $vendorprefix, all of them will now be
-changed to the new prefix, /foo/bar. (Previously only $prefix
-changed.) If you do not like this new behaviour, specify prefix,
-siteprefix, and vendorprefix explicitly.
+=item *
-=head2 Additional Library Locations
+C<ExtUtils::Constant> is a new tool for extension writers for
+generating XS code to import C header constants, by Nicholas Clark.
+See L<ExtUtils::Constant>.
-A new optional location for Perl libraries, otherlibdirs, is available.
-It can be used for example for vendor add-ons without disturbing Perl's
-own library directories.
+=item *
-=head2 gcc automatically tried if 'cc' does not seem to be working
+C<Filter::Simple> is an easy-to-use frontend to Filter::Util::Call,
+from Damian Conway. See L<Filter::Simple>.
-In many platforms the vendor-supplied 'cc' is too stripped-down to
-build Perl (basically, the 'cc' doesn't do ANSI C). If this seems
-to be the case and the 'cc' does not seem to be the GNU C compiler
-'gcc', an automatic attempt is made to find and use 'gcc' instead.
+ # in MyFilter.pm:
-=head2 If gcc seems to be from a different operating system release ...
+ package MyFilter;
-gcc needs to closely track the operating system release because gcc
-wants to have its own versions of the operating system header files
-fixed to be clean enough for gcc's tastes. Therefore using a gcc
-compiled for a different release of the operating system is often a
-bad idea. If Configure can find out the operating system release that
-was used to compile the gcc and that release is different from the one
-being used now, gcc gives a clearly visible warning that trouble may
-lie ahead.
+ use Filter::Simple sub {
+ while (my ($from, $to) = splice @_, 0, 2) {
+ s/$from/$to/g;
+ }
+ };
-=head2 If no binary compatibility with 5.005 wanted, no 5.005 modules, either
+ 1;
-If no binary compatibility with the 5.005 release is wanted, Configure
-does not suggest including the 5.005 modules in the @INC.
+ # in user's code:
-=head2 Configuration and Installation Fixes
+ use MyFilter qr/red/ => 'green';
-=over 4
+ print "red\n"; # this code is filtered, will print "green\n"
+ print "bored\n"; # this code is filtered, will print "bogreen\n"
-=item *
+ no MyFilter;
-Configure C<-S> can now run non-interactively
+ print "red\n"; # this code is not filtered, will print "red\n"
=item *
-configure.gnu now works with options with whitespace in them
+C<File::Temp> allows one to create temporary files and directories in
+an easy, portable, and secure way, by Tim Jenness. See L<File::Temp>.
=item *
-installperl now outputs everything to STDERR
+C<Filter::Util::Call> provides you with the framework to write
+I<Source Filters> in Perl, from Paul Marquess. For most uses the
+frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
=item *
-$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.)
+L<libnet> is a collection of perl5 modules related to network
+programming, from Graham Barr. See L<Net::FTP>, L<Net::NNTP>,
+L<Net::Ping>, L<Net::POP3>, L<Net::SMTP>, and L<Net::Time>.
-=back
+Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
-=head1 Platform Specific Changes and Fixes
+=item *
-=head2 BSDI 4.*
+C<List::Util> is a selection of general-utility list subroutines, like
+sum(), min(), first(), and shuffle(), by Graham Barr. See L<List::Util>.
-Perl now works on post-4.0 BSD/OSes.
+=item *
-=head2 All BSDs
+C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>, and
+C<Locale::Language>, from Neil Bowers, have been added. They provide the
+codes for various locale standards, such as "fr" for France, "usd" for
+US Dollar, and "jp" for Japanese.
-Setting the C<$0> now works (as much as possible; see perlvar for details).
+ use Locale::Country;
-=head2 Cygwin
+ $country = code2country('jp'); # $country gets 'Japan'
+ $code = country2code('Norway'); # $code gets 'no'
-=over 4
+See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
+and L<Locale::Language>.
=item *
-Numerous updates; currently synchronised with Cygwin 1.1.4.
+C<Locale::Maketext> is localization framework from Sean Burke. See
+L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
+article about software localization, originally published in The Perl
+Journal #13, republished here with kind permission.
-=back
+=item *
-=head2 EPOC
+C<Memoize> can make your functions faster by trading space for time,
+from Mark-Jason Dominus. See L<Memoize>.
-EPOC update after Perl 5.6.0. The EPOC port home page is at
-http://members.linuxstart.com/~oflebbe/perl/perl5.html
+=item *
-=head2 FreeBSD 3.*
+C<MIME::Base64> allows you to encode data in base64, from Gisle Aas,
+as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
+Extensions)>.
-Perl now works on post-3.0 FreeBSDs.
+ use MIME::Base64;
-=head2 HP-UX
+ $encoded = encode_base64('Aladdin:open sesame');
+ $decoded = decode_base64($encoded);
-=over 4
+ print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
+
+See L<MIME::Base64>.
=item *
-Document that the C<perl -P> causes problems if one uses C<s/foo//>
-(because the HP C compiler does funny things to that // thinking it
-to be C++), document also the workaround.
+C<MIME::QuotedPrint> allows you to encode data in quoted-printable
+encoding, as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
+Extensions)>, from Gisle Aas.
-=item *
+ use MIME::QuotedPrint;
-C<Configure -Duse64bitall> now almost works (one failing test).
+ $encoded = encode_qp("Smiley in Unicode: \x{263a}");
+ $decoded = decode_qp($encoded);
-=back
+ print $encoded, "\n"; # "Smiley in Unicode: =263A"
-=head2 IRIX
+MIME::QuotedPrint has been enhanced to provide the basic methods
+necessary to use it with PerlIO::Via as in :
-=over 4
+ use MIME::QuotedPrint;
+ open($fh,">Via(MIME::QuotedPrint)",$path);
+
+See L<MIME::QuotedPrint>.
=item *
-Numerous compilation flag and hint enhancements.
+C<NEXT> is pseudo-class for method redispatch, from Damian Conway.
+See L<NEXT>.
=item *
-Accidental mixing of 32-bit and 64-bit libraries (a doomed attempt)
-made much harder.
+C<open> is a new pragma for setting the default I/O disciplines
+for open().
-=back
-
-=head2 Linux
+=item *
-=over 4
+C<PerlIO::Scalar> provides the implementation of IO to "in memory"
+Perl scalars as discussed above, from Nick Ing-Simmons. It also
+serves as an example of a loadable PerlIO layer. Other future
+possibilities include PerlIO::Array and PerlIO::Code.
+See L<PerlIO::Scalar>.
=item *
-Long doubles should now work (see INSTALL).
-
-=back
+C<PerlIO::Via> acts as a PerlIO layer and wraps PerlIO layer
+functionality provided by a class (typically implemented in perl
+code), from Nick Ing-Simmons.
-=head2 MacOS Classic
+ use MIME::QuotedPrint;
+ open($fh,">Via(MIME::QuotedPrint)",$path);
-=over 4
+This will automatically convert everything output to C<$fh>
+to Quoted-Printable. See L<PerlIO::Via>.
=item *
-Compilation of the standard Perl distribution in MacOS Classic should
-now work--assuming you have the Metrowerks development environment and
-the missing Mac-specific toolkit bits, contact the macperl mailing
-list for details.
+C<Pod::ParseLink>, by Russ Allbery, has been added,
+to parse LZ<><> links in pods as described in the new
+perlpodspec.
-=back
+=item *
-=head2 MPE/iX
+C<Pod::Text::Overstrike>, by Joe Smith, has been added.
+It converts POD data to formatted overstrike text.
+See L<Pod::Text::Overstrike>.
-MPE/iX update after Perl 5.6.0. The Perl/iX home page is at
-http://www.bixby.org/mark/perlix.html
+=item *
-=head2 NetBSD/sparc
+C<Scalar::Util> is a selection of general-utility scalar subroutines,
+like blessed(), reftype(), and tainted(). See L<Scalar::Util>.
-Perl now works on NetBSD/sparc.
+=item *
-=head2 OS/2
+C<sort> is a new pragma for controlling the behaviour of sort().
-=over 4
+=item *
+
+C<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, from Raphael Manfredi. See L<Storable>.
=item *
-Now works with usethreads (see INSTALL).
+C<Switch>, from Damian Conway, has been added. Just by saying
-=back
+ use Switch;
-=head2 Solaris
+you have C<switch> and C<case> available in Perl.
-=over 4
+ use Switch;
-=item *
+ switch ($val) {
-64-bitness using the Sun Workshop compiler now works.
+ 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 /\w+/ { print "pattern" }
+ case qr/\w+/ { print "pattern" }
+ case (%hash) { print "entry in hash" }
+ case (\%hash) { print "entry in hash" }
+ case (\&sub) { print "arg to subroutine" }
+ else { print "previous case not true" }
+ }
-=back
+See L<Switch>.
-=head2 Tru64 (aka Digital UNIX, aka DEC OSF/1)
+=item *
-=over 4
+C<Test::More> is yet another framework for writing test scripts,
+more extensive than Test::Simple, by Michael Schwern. See L<Test::More>.
=item *
-Allow compiling with gcc (previously explicitly forbidden). Compiling
-with gcc still not recommended because buggy code results, even with
-gcc 2.95.2.
+C<Test::Simple> has basic utilities for writing tests, by Michael
+Schwern. See L<Test::Simple>.
=item *
-The operating system version letter now recorded in $Config{osvers}.
+C<Text::Balanced> has been added, for extracting delimited text
+sequences from strings, from Damian Conway.
-=back
+ use Text::Balanced 'extract_delimited';
-=head2 Unicos
+ ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
-=over 4
+$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_delimited_pat(), and
+gen_extract_tagged(). With these you can implement rather advanced
+parsing algorithms. See L<Text::Balanced>.
=item *
-Fixed various alignment problems that lead into core dumps either
-during build or later.
+C<threads> is an interface to interpreter threads, by Arthur Bergman.
+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 C<fork()> emulation). See L<threads>.
=item *
-no longer dying on math errors in runtime.
+C<threads::shared> allows data sharing for interpreter threads, from
+Arthur Bergman. In the ithreads model any data sharing between
+threads must be explicit, as opposed to the old 5.005 thread model
+where data sharing was implicit. See L<threads::shared>.
=item *
-Now using full quad integers (64 bits), previously was using
-only 46 bit integers for speed.
+C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash
+references (unlike the standard Tie::RefHash) The module is contained
+within Tie::RefHash, see L<Tie::RefHash>.
-=back
+=item *
-=head2 VMS
+C<Time::HiRes> provides high resolution timing (ualarm, usleep,
+and gettimeofday), from Douglas E. Wegscheid. See L<Time::HiRes>.
-=over 4
+=item *
+
+C<Unicode::UCD> offers a querying interface to the Unicode Character
+Database. See L<Unicode::UCD>.
=item *
-chdir() now works better despite a CRT bug.
+C<Unicode::Collate> implements the UCA (Unicode Collation Algorithm)
+for sorting Unicode strings, by SADAHIRO Tomoyuki. See L<Unicode::Collate>.
=item *
-Now works with MULTIPLICITY (see INSTALL).
+C<Unicode::Normalize> implements the various Unicode normalization
+forms, by SADAHIRO Tomoyuki. See L<Unicode::Normalize>.
=item *
-Now works with Perl's malloc.
+C<XS::Typemap>, by Tim Jenness, is a test extension that exercises XS
+typemaps. Nothing gets installed but for extension writers the code
+is worth studying.
=back
-=head2 Windows
+=head2 Updated And Improved Modules and Pragmata
=over 4
=item *
-accept() no longer leaks memory.
+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, Pod::Parser, Storable,
+Term::ANSIColor, Test, Text-Tabs+Wrap.
=item *
-Better chdir() return value for a non-existent directory.
+The attributes::reftype() now works on tied arguments.
=item *
-New %ENV entries now propagate to subprocesses.
+AutoLoader can now be disabled with C<no AutoLoader;>.
=item *
-$ENV{LIB} now used to search for libs under Visual C.
+B::Deparse has been significantly enhanced. It now can 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.
=item *
-A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
+Class::Struct can now define the classes in compile time.
=item *
-Allow REG_EXPAND_SZ keys in the registry.
+Class::Struct now assigns the array/hash element if the accessor
+is called with an array/hash element as the B<sole> argument.
=item *
-Can now send() from all threads, not just the first one.
+Data::Dumper has now an option to sort hashes.
=item *
-Fake signal handling reenabled, bugs and all.
+Data::Dumper has now an option to dump code references
+using B::Deparse.
=item *
-Less stack reserved per thread so that more threads can run
-concurrently. (still 16M perl thread)
+DB_File now supports newer Berkeley DB versions, among
+other improvements.
=item *
-C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
-(works better when perl running as service).
+The English module can now be used without the infamous performance
+hit by saying
-=item *
+ use English '-no_performance_hit';
-Better UNC path handling under ithreads.
+(Assuming, of course, that one doesn't need the troublesome variables
+C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
+C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
=item *
-wait() and waitpid() now work much better.
+Fcntl, Socket, and Sys::Syslog have been rewritten to use the
+new-style constant dispatch section (see L<ExtUtils::Constant>).
+This means that they will be more robust and hopefully faster.
=item *
-winsock handle leak fixed.
-
-=back
+File::Find now chdir()s correctly when chasing symbolic links.
-=head1 Selected Bug Fixes
+=item *
-=over 4
+File::Find now has pre- and post-processing callbacks. It also
+correctly changes directories when chasing symbolic links. Callbacks
+(naughtily) exiting with "next;" instead of "return;" now work.
=item *
-Several debugger fixes: exit code now reflects the script exit code,
-condition C<"0"> now treated correctly, the C<d> command now checks
-line number, the C<$.> no longer gets corrupted, all debugger output now
-goes correctly to the socket if RemotePort is set.
+File::Find is now (again) reentrant. It also has been made
+more portable.
=item *
-C<*foo{FORMAT}> now works.
+File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
+prototype mismatch with CORE::glob().
=item *
-Lexical warnings now propagating correctly between scopes.
+File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
+the returned list of filenames.
=item *
-Line renumbering with eval and C<#line> now works.
+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).
=item *
-Module name now mandatory after the C<-M> switch.
+IPC::Open3 now allows the use of numeric file descriptors.
=item *
-Fixed numerous memory leaks, especially in eval "".
+IO::Socket has now 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.
=item *
-Modulus of unsigned numbers now works (4063328477 % 65535 used to
-return 27406, instead of 27047).
+IO::Socket::INET has support for ReusePort option (if your platform
+supports it). The Reuse option now has an alias, ReuseAddr. For clarity
+you may want to prefer ReuseAddr.
=item *
-Some "not a number" warnings introduced in 5.6.0 eliminated to be
-more compatible with 5.005. Infinity is now recognised as a number.
+IO::Socket::INET now supports C<LocalPort> of zero (usually meaning
+that the operating system will make one up.)
=item *
-our() variables will not cause "will not stay shared" warnings
+use lib now works identically to @INC. Removing directories
+with 'no lib' now works.
=item *
-pack "Z" now correctly terminates the string with an "\0".
+ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
+leads into better portability.
=item *
-Fix password routines which in some shadow password platforms
-(e.g. HP-UX) caused getpwent() to return every other entry.
+Math::BigFloat and Math::BigInt have undergone a full rewrite.
+They are now magnitudes faster, and they support various
+bignum libraries such as GMP and PARI as their backends.
=item *
-printf() no longer resets the numeric locale to "C".
+Math::Complex handles inf, NaN etc., better.
=item *
-C<q(a\\b)> now parses correctly as C<'a\\b'>.
+Net::Ping has been muchly enhanced. Multihoming is now supported.
+There is now "external" protocol which uses Net::Ping::External module
+which runs external ping(1) and parses the output. A version of
+Net::Ping::External is available in CPAN.
=item *
-Printing quads (64-bit integers) with printf/sprintf works now
-without q L ll prefixes (assuming you are on a quad-capable platform).
+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.
=item *
-Regular expressions on references and overloaded scalars now work.
+In Safe the C<%INC> now localised in a Safe compartment so that
+use/require work.
=item *
-scalar() now forces scalar context even when used in void context.
+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.
=item *
-
+
+In Search::Dict one can now have a pre-processing hook for the
+lines being searched.
+
+=item *
+
+The Shell module now has an OO interface.
+
+=item *
+
+The Test module has been significantly enhanced.
+
+=item *
+
+The vars pragma now supports declaring fully qualified variables.
+(Something that C<our()> does not and will not support.)
+
+=item *
+
+The C<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.
+
+=back
+
+=head1 Utility Changes
+
+=over 4
+
+=item *
+
+Emacs perl mode (emacs/cperl-mode.el) has been updated to version
+4.31.
+
+=item *
+
+F<emacs/e2ctags.pl> is now much faster.
+
+=item *
+
+C<h2ph> now supports C trigraphs.
+
+=item *
+
+C<h2xs> now produces a template README.
+
+=item *
+
+C<h2xs> now uses C<Devel::PPort> for better portability between
+different versions of Perl.
+
+=item *
+
+C<h2xs> uses the new L<ExtUtils::Constant> module which will affect
+newly created extensions that define constants. Since the new code is
+more correct (if you have two constants where the first one is a
+prefix of the second one, the first constant B<never> gets defined),
+less lossy (it uses integers for integer constant, as opposed to the
+old code that used floating point numbers even for integer constants),
+and slightly faster, you might want to consider regenerating your
+extension code (the new scheme makes regenerating easy).
+L<h2xs> now also supports C trigraphs.
+
+=item *
+
+C<libnetcfg> has been added to configure the libnet.
+
+=item *
+
+C<perlbug> is now much more robust. It also sends the bug report to
+perl.org, not perl.com.
+
+=item *
+
+C<perlcc> has been rewritten and its user interface (that is,
+command line) is much more like that of the UNIX C compiler, cc.
+(The perlbc tools has been removed. Use C<perlcc -B> instead.)
+
+=item *
+
+C<perlivp> is a new Installation Verification Procedure utility
+for running any time after installing Perl.
+
+=item *
+
+C<pod2html> now allows specifying a cache directory.
+
+=item *
+
+C<s2p> has been completely rewritten in Perl. (It is in fact a full
+implementation of sed in Perl: you can use the sed functionality by
+using the C<psed> utility.)
+
+=item *
+
+C<xsubpp> now understands POD documentation embedded in the *.xs files.
+
+=item *
+
+C<xsubpp> now supports OUT keyword.
+
+=back
+
+=head1 New Documentation
+
+=over 4
+
+=item *
+
+perl56delta details the changes between the 5.005 release and the
+5.6.0 release.
+
+=item *
+
+perlclib documents the internal replacements for standard C library
+functions. (Interesting only for extension writers and Perl core
+hackers.)
+
+=item *
+
+perldebtut is a Perl debugging tutorial.
+
+=item *
+
+perlebcdic contains considerations for running Perl on EBCDIC platforms.
+
+=item *
+
+perlintro is a gentle introduction to Perl.
+
+=item *
+
+perliol documents the internals of PerlIO with layers.
+
+=item *
+
+perlmodstyle is a style guide for writing modules.
+
+=item *
+
+perlnewmod tells about writing and submitting a new module.
+
+=item *
+
+perlpacktut is a pack() tutorial.
+
+=item *
+
+perlpod has been rewritten to be clearer and to record the best
+practices gathered over the years.
+
+=item *
+
+perlpodspec is a more formal specification of the pod format,
+mainly of interest for writers of pod applications, not to
+people writing in pod.
+
+=item *
+
+perlretut is a regular expression tutorial.
+
+=item *
+
+perlrequick is a regular expressions quick-start guide.
+Yes, much quicker than perlretut.
+
+=item *
+
+perltodo has been updated.
+
+=item *
+
+perltootc has been renamed as perltooc (to not to conflict
+with perltoot in filesystems restricted to "8.3" names)
+
+=item *
+
+perluniintro is an introduction to using Unicode in Perl.
+(perlunicode is more of a detailed reference and background
+information)
+
+=item *
+
+perlutil explains the command line utilities packaged with the Perl
+distribution.
+
+=back
+
+The following platform-specific documents are available before
+the installation as README.I<platform>, and after the installation
+as perlI<platform>:
+
+ perlaix perlamiga perlapollo perlbeos perlbs2000
+ perlce perlcygwin perldgux perldos perlepoc perlhpux
+ perlhurd perlmachten perlmacos perlmint perlmpeix
+ perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
+ perltru64 perluts perlvmesa perlvms perlvos perlwin32
+
+=over 4
+
+=item *
+
+The documentation for the POSIX-BC platform is called "BS2000", to avoid
+confusion with the Perl POSIX module.
+
+=item *
+
+The documentation for the WinCE platform is called "CE", to avoid
+confusion with the perlwin32 documentation on 8.3-restricted filesystems.
+
+=back
+
+=head1 Performance Enhancements
+
+=over 4
+
+=item *
+
+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.
+
+=item *
+
+sort() has been changed to use primarily mergesort internally as
+opposed to the earlier quicksort. For very small lists this may
+result in slightly slower sorting times, but in general the speedup
+should be at least 20%. Additional bonuses are that the worst case
+behaviour of sort() is now better (in computer science terms it now
+runs in time O(N log N), as opposed to quicksort's Theta(N**2)
+worst-case run time behaviour), and that sort() is now stable
+(meaning that elements with identical keys will stay ordered as they
+were before the sort). See the C<sort> pragma for information.
+
+The story in more detail: suppose you want to serve yourself a little
+slice of Pi.
+
+ @digits = ( 3,1,4,1,5,9 );
+
+A numerical sort of the digits will yield (1,1,3,4,5,9), as expected.
+Which C<1> comes first is hard to know, since one C<1> looks pretty
+much like any other. You can regard this as totally trivial,
+or somewhat profound. However, if you just want to sort the even
+digits ahead of the odd ones, then what will
+
+ sort { ($a % 2) <=> ($b % 2) } @digits;
+
+yield? The only even digit, C<4>, will come first. But how about
+the odd numbers, which all compare equal? With the quicksort algorithm
+used to implement Perl 5.6 and earlier, the order of ties is left up
+to the sort. So, as you add more and more digits of Pi, the order
+in which the sorted even and odd digits appear will change.
+and, for sufficiently large slices of Pi, the quicksort algorithm
+in Perl 5.8 won't return the same results even if reinvoked with the
+same input. The justification for this rests with quicksort's
+worst case behavior. If you run
+
+ sort { $a <=> $b } ( 1 .. $N , 1 .. $N );
+
+(something you might approximate if you wanted to merge two sorted
+arrays using sort), doubling $N doesn't just double the quicksort time,
+it I<quadruples> it. Quicksort has a worst case run time that can
+grow like N**2, so-called I<quadratic> behaviour, and it can happen
+on patterns that may well arise in normal use. You won't notice this
+for small arrays, but you I<will> notice it with larger arrays,
+and you may not live long enough for the sort to complete on arrays
+of a million elements. So the 5.8 quicksort scrambles large arrays
+before sorting them, as a statistical defence against quadratic behaviour.
+But that means if you sort the same large array twice, ties may be
+broken in different ways.
+
+Because of the unpredictability of tie-breaking order, and the quadratic
+worst-case behaviour, quicksort was I<almost> replaced completely with
+a stable mergesort. I<Stable> means that ties are broken to preserve
+the original order of appearance in the input array. So
+
+ sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
+
+will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
+appear in the output in the same order they appeared in the input.
+Mergesort has worst case O(NlogN) behaviour, the best value
+attainable. And, ironically, this mergesort does particularly
+well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N)
+in O(N) time. But quicksort was rescued at the last moment because
+it is faster than mergesort on certain inputs and platforms.
+For example, if you really I<don't> care about the order of even
+and odd digits, quicksort will run in O(N) time; it's very good
+at sorting many repetitions of a small number of distinct elements.
+The quicksort divide and conquer strategy works well on platforms
+with relatively small, very fast, caches. Eventually, the problem gets
+whittled down to one that fits in the cache, from which point it
+benefits from the increased memory speed.
+
+Quicksort was rescued by implementing a sort pragma to control aspects
+of the sort. The B<stable> subpragma forces stable behaviour,
+regardless of algorithm. The B<_quicksort> and B<_mergesort>
+subpragmas are heavy-handed ways to select the underlying implementation.
+The leading C<_> is a reminder that these subpragmas may not survive
+beyond 5.8. More appropriate mechanisms for selecting the implementation
+exist, but they wouldn't have arrived in time to save quicksort.
+
+=item *
+
+Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
+(http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
+reasonably fast while producing a much better spread of values than
+the old hashing algorithm (originally by Chris Torek, later tweaked by
+Ilya Zakharevich). Hash values output from the algorithm on a hash of
+all 3-char printable ASCII keys comes much closer to passing the
+DIEHARD random number generation tests. According to perlbench, this
+change has not affected the overall speed of Perl.
+
+=item *
+
+unshift() should now be noticeably faster.
+
+=back
+
+=head1 Installation and Configuration Improvements
+
+=head2 Generic Improvements
+
+=over 4
+
+=item *
+
+INSTALL now explains how you can configure Perl to use 64-bit
+integers even on non-64-bit platforms.
+
+=item *
+
+Policy.sh policy change: if you are reusing a Policy.sh file
+(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
+Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
+them will now be changed to the new prefix, /foo/bar. (Previously
+only $prefix changed.) If you do not like this new behaviour,
+specify prefix, siteprefix, and vendorprefix explicitly.
+
+=item *
+
+A new optional location for Perl libraries, otherlibdirs, is available.
+It can be used for example for vendor add-ons without disturbing Perl's
+own library directories.
+
+=item *
+
+In many platforms the vendor-supplied 'cc' is too stripped-down to
+build Perl (basically, 'cc' doesn't do ANSI C). If this seems
+to be the case and 'cc' does not seem to be the GNU C compiler
+'gcc', an automatic attempt is made to find and use 'gcc' instead.
+
+=item *
+
+gcc needs to closely track the operating system release to avoid
+build problems. If Configure finds that gcc was built for a different
+operating system release than is running, it now gives a clearly visible
+warning that there may be trouble ahead.
+
+=item *
+
+If binary compatibility with the 5.005 release is not wanted, Configure
+no longer suggests including the 5.005 modules in @INC.
+
+=item *
+
+Configure C<-S> can now run non-interactively.
+
+=item *
+
+Configure support for pdp11-style memory models has been removed due
+to obsolescence.
+
+=item *
+
+configure.gnu now works with options with whitespace in them.
+
+=item *
+
+installperl now outputs everything to STDERR.
+
+=item *
+
+$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.)
+
+=item *
+
+Because PerlIO is now the default on most platforms, "-perlio" doesn't
+get appended to the $Config{archname} (also known as $^O) anymore.
+Instead, if you explicitly choose not to use perlio (Configure command
+line option -Uuseperlio), you will get "-stdio" appended.
+
+=item *
+
+Another change related to the architecture name is that "-64all"
+(-Duse64bitall, or "maximally 64-bit") is appended only if your
+pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
+
+=item *
+
+In AFS installations one can configure the root of the AFS to be
+somewhere else than the default F</afs> by using the Configure
+parameter C<-Dafsroot=/some/where/else>.
+
+=item *
+
+APPLLIB_EXP, a less-know configuration-time definition, has been
+documented. It can be used to prepend site-specific directories
+to Perl's default search path (@INC), see INSTALL for information.
+
+=item *
+
+The version of Berkeley DB used when the Perl (and, presumably, the
+DB_File extension) was built is now available as
+C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
+from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
+DB_VERSION_PATCH_CFG> from C.
+
+=item *
+
+Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
+has been documented in INSTALL.
+
+=item *
+
+If you have CPAN access (either network or a local copy such as a
+CD-ROM) you can during specify extra modules to Configure to build and
+install with Perl using the -Dextras=... option. See INSTALL for
+more details.
+
+=item *
+
+In addition to config.over a new override file, config.arch, is
+available. That is supposed to be used by hints file writers for
+architecture-wide changes (as opposed to config.over which is for
+site-wide changes).
+
+=item *
+
+If your file system supports symbolic links you can build Perl outside
+of the source directory by
+
+ mkdir /tmp/perl/build/directory
+ cd /tmp/perl/build/directory
+ sh /path/to/perl/source/Configure -Dmksymlinks ...
+
+This will create in /tmp/perl/build/directory a tree of symbolic links
+pointing to files in /path/to/perl/source. The original files are left
+unaffected. After Configure has finished you can just say
+
+ make all test
+
+and Perl will be built and tested, all in /tmp/perl/build/directory.
+
+=item *
+
+For Perl developers several new make targets for profiling
+and debugging have been added, see L<perlhack>.
+
+=over 8
+
+=item *
+
+Use of the F<gprof> tool to profile Perl has been documented in
+L<perlhack>. There is a make target called "perl.gprof" for
+generating a gprofiled Perl executable.
+
+=item *
+
+If you have GCC 3, there is a make target called "perl.gcov" for
+creating a gcoved Perl executable for coverage analysis. See
+L<perlhack>.
+
+=item *
+
+If you are on IRIX or Tru64 platforms, new profiling/debugging options
+have been added, see L<perlhack> for more information about pixie and
+Third Degree.
+
+=back
+
+=item *
+
+Guidelines of how to construct minimal Perl installations have
+been added to INSTALL.
+
+=item *
+
+The Thread extension is now not built at all under ithreads
+(C<Configure -Duseithreads>) because it wouldn't work anyway (the
+Thread extension requires being Configured with C<-Duse5005threads>).
+
+But note that the Thread.pm interface is now shared by both
+thread models.
+
+=back
+
+=head2 New Or Improved Platforms
+
+For the list of platforms known to support Perl,
+see L<perlport/"Supported Platforms">.
+
+=over 4
+
+=item *
+
+AIX dynamic loading should be now better supported.
+
+=item *
+
+AIX should now work better with gcc, threads, and 64-bitness. Also the
+long doubles support in AIX should be better now. See L<perlaix>.
+
+=item *
+
+After a long pause, AmigaOS has been verified to be happy with Perl.
+
+=item *
+
+AtheOS (http://www.atheos.cx/) is a new platform.
+
+=item *
+
+BeOS has been reclaimed.
+
+=item *
+
+DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
+
+=item *
+
+DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
+
+=item *
+
+EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
+have been regained. Many test suite tests still fail and the
+co-existence of Unicode and EBCDIC isn't quite settled, but the
+situation is much better than with Perl 5.6. See L<perlos390>,
+L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
+
+=item *
+
+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.
+
+=item *
+
+MacOS Classic (MacPerl has of course been available since
+perl 5.004 but now the source code bases of standard Perl
+and MacPerl have been synchronised)
+
+=item *
+
+MacOS X (or Darwin) should now be able to build Perl even on HFS+
+filesystems. (The case-insensitivity confused the Perl build process.)
+
+=item *
+
+NCR MP-RAS is now supported.
+
+=item *
+
+All the NetBSD specific patches (except for the installation
+specific ones) have been merged back to the main distribution.
+
+=item *
+
+NetWare from Novell is now supported. See L<perlnetware>.
+
+=item *
+
+NonStop-UX is now supported.
+
+=item *
+
+NEC SUPER-UX is now supported.
+
+=item *
+
+All the OpenBSD specific patches (except for the installation
+specific ones) have been merged back to the main distribution.
+
+=item *
+
+Perl has been tested with the GNU pth userlevel thread package
+( http://www.gnu.org/software/pth/pth.html ) . All but one thread
+test worked, and that one failure was because of test results arriving
+in unexpected order.
+
+=item *
+
+Amdahl UTS UNIX mainframe platform is now supported.
+
+=item *
+
+WinCE is now supported. See L<perlce>.
+
+=item *
+
+z/OS (formerly known as OS/390, formerly known as MVS OE) has now
+support for dynamic loading. This is not selected by default,
+however, you must specify -Dusedl in the arguments of Configure.
+
+=back
+
+=head1 Selected Bug Fixes
+
+Numerous memory leaks and uninitialized memory accesses have been
+hunted down. Most importantly anonymous subs used to leak quite
+a bit.
+
+=over 4
+
+=item *
+
+The autouse pragma didn't work for Multi::Part::Function::Names.
+
+=item *
+
+caller() could cause core dumps in certain situations. Carp was sometimes
+affected by this problem.
+
+=item *
+
+chop(@list) in list context returned the characters chopped in
+reverse order. This has been reversed to be in the right order.
+
+=item *
+
+Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
+when building the Perl binary. The only exception to this is SunOS 4.x,
+which needs them.
+
+=item *
+
+The behaviour of non-decimal but numeric string constants such as
+"0x23" was platform-dependent: in some platforms that was seen as 35,
+in some as 0, in some as a floating point number (don't ask). This
+was caused by Perl using the operating system libraries in a situation
+where the result of the string to number conversion is undefined: now
+Perl consistently handles such strings as zero in numeric contexts.
+
+=item *
+
+The order of DESTROYs has been made more predictable.
+
+=item *
+
+Several debugger fixes: exit code now reflects the script exit code,
+condition C<"0"> now treated correctly, the C<d> command now checks
+line number, the C<$.> no longer gets corrupted, all debugger output
+now goes correctly to the socket if RemotePort is set.
+
+=item *
+
+Perl 5.6.0 could emit spurious warnings about redefinition of dl_error()
+when statically building extensions into perl. This has been corrected.
+
+=item *
+
+L<dprofpp> -R didn't work.
+
+=item *
+
+C<*foo{FORMAT}> now works.
+=item *
+
+Infinity is now recognized as a number.
+
+=item *
+
+UNIVERSAL::isa no longer caches methods incorrectly. (This broke
+the Tk extension with 5.6.0.)
+
+=item *
+
+Lexicals I: lexicals outside an eval "" weren't resolved
+correctly inside a subroutine definition inside the eval "" if they
+were not already referenced in the top level of the eval""ed code.
+
+=item *
+
+Lexicals II: lexicals leaked at file scope into subroutines that
+were declared before the lexicals.
+
+=item *
+
+Lexical warnings now propagating correctly between scopes
+and into C<eval "...">.
+
+=item *
+
+C<use warnings qw(FATAL all)> did not work as intended. This has been
+corrected.
+
+=item *
+
+warnings::enabled() now reports the state of $^W correctly if the caller
+isn't using lexical warnings.
+
+=item *
+
+Line renumbering with eval and C<#line> now works.
+
+=item *
+
+Fixed numerous memory leaks, especially in eval "".
+
+=item *
+
+mkdir() now ignores trailing slashes in the directory name,
+as mandated by POSIX.
+
+=item *
+
+Some versions of glibc have a broken modfl(). This affects builds
+with C<-Duselongdouble>. This version of Perl detects this brokenness
+and has a workaround for it. The glibc release 2.2.2 is known to have
+fixed the modfl() bug.
+
+=item *
+
+Modulus of unsigned numbers now works (4063328477 % 65535 used to
+return 27406, instead of 27047).
+
+=item *
+
+Some "not a number" warnings introduced in 5.6.0 eliminated to be
+more compatible with 5.005. Infinity is now recognised as a number.
+
+=item *
+
+Numeric conversions did not recognize changes in the string value
+properly in certain circumstances.
+
+=item *
+
+Attributes (like :shared) didn't work with our().
+
+=item *
+
+our() variables will not cause "will not stay shared" warnings.
+
+=item *
+
+"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.
+
+=item *
+
+pack "Z" now correctly terminates the string with "\0".
+
+=item *
+
+Fix password routines which in some shadow password platforms
+(e.g. HP-UX) caused getpwent() to return every other entry.
+
+=item *
+
+The PERL5OPT environment variable (for passing command line arguments
+to Perl) didn't work for more than a single group of options.
+
+=item *
+
+PERL5OPT with embedded spaces didn't work.
+
+=item *
+
+printf() no longer resets the numeric locale to "C".
+
+=item *
+
+C<qw(a\\b)> now parses correctly as C<'a\\b'>.
+
+=item *
+
+pos() did not return the correct value within s///ge in earlier
+versions. This is now handled correctly.
+
+=item *
+
+Printing quads (64-bit integers) with printf/sprintf now works
+without the q L ll prefixes (assuming you are on a quad-capable platform).
+
+=item *
+
+Regular expressions on references and overloaded scalars now work.
+
+=item *
+
+Right-hand side magic (GMAGIC) could in many cases such as string
+concatenation be invoked too many times.
+
+=item *
+
+scalar() now forces scalar context even when used in void context.
+
+=item *
+
+SOCKS support is now much more robust.
+
+=item *
+
sort() arguments are now compiled in the right wantarray context
(they were accidentally using the context of the sort() itself).
+The comparison block is now run in scalar context, and the arguments
+to be sorted are always provided list context.
+
+=item *
+
+Changed the POSIX character class C<[[:space:]]> to include the (very
+rarely used) vertical tab character. Added a new POSIX-ish character
+class C<[[:blank:]]> which stands for horizontal whitespace
+(currently, the space and the tab).
+
+=item *
+
+The tainting behaviour of sprintf() has been rationalized. It does
+not taint the result of floating point formats anymore, making the
+behaviour consistent with that of string interpolation.
+
+=item *
+
+Some cases of inconsistent taint propagation (such as within hash
+values) have been fixed.
+
+=item *
+
+The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds
+of simple pattern matches. These are now handled better.
+
+=item *
+
+Regular expression debug output (whether through C<use re 'debug'>
+or via C<-Dr>) now looks better.
+
+=item *
+
+Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
+bug has been fixed.
+
+=item *
+
+Use of $& could trigger a core dump under some situations. This
+is now avoided.
+
+=item *
+
+The regular expression captured submatches ($1, $2, ...) are now
+more consistently unset if the match fails, instead of leaving false
+data lying around in them.
+
+=item *
+
+readline() on files opened in "slurp" mode could return an extra "" at
+the end in certain situations. This has been corrected.
+
+=item *
+
+Autovivification of symbolic references of special variables described
+in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
+again now.
+
+=item *
+
+Sys::Syslog ignored the C<LOG_AUTH> constant.
+
+=item *
+
+All but the first argument of the IO syswrite() method are now optional.
+
+=item *
+
+$AUTOLOAD, sort(), lock(), and spawning subprocesses
+in multiple threads simultaneously are now thread-safe.
+
+=item *
+
+Tie::ARRAY SPLICE method was broken.
+
+=item *
+
+Allow read-only string on left hand side of non-modifying tr///.
+
+=item *
+
+Several Unicode fixes.
+
+=over 8
+
+=item *
+
+BOMs (byte order marks) in the beginning of Perl files
+(scripts, modules) should now be transparently skipped.
+UTF-16 (UCS-2) encoded Perl files should now be read correctly.
+
+=item *
+
+The character tables have been updated to Unicode 3.1.1.
+
+=item *
+
+Comparing with utf8 data does not magically upgrade non-utf8 data
+into utf8. (This was a problem for example if you were mixing data
+from I/O and Unicode data: your output might have got magically encoded
+as UTF-8.)
+
+=item *
+
+Generating illegal Unicode code points like U+FFFE, or the UTF-16
+surrogates, now also generates an optional warning.
+
+=item *
+
+C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
+
+=item *
+
+Concatenation with the C<.> operator or via variable interpolation,
+C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
+substitution with C<s///>, single-quoted UTF8, should now work.
+
+=item *
+
+The C<tr///> operator now works. Note that the C<tr///CU>
+functionality has been removed (but see pack('U0', ...)).
+
+=item *
+
+C<eval "v200"> now works.
+
+=item *
+
+Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings.
+This has been corrected.
+
+=item *
+
+Zero entries were missing from the Unicode classes like C<IsDigit>.
+
+=back
+
+=item *
+
+Large unsigned numbers (those above 2**31) could sometimes lose their
+unsignedness, causing bogus results in arithmetic operations.
+
+=back
+
+=head2 Platform Specific Changes and Fixes
+
+=over 4
+
+=item *
+
+BSDI 4.*
+
+Perl now works on post-4.0 BSD/OSes.
+
+=item *
+
+All BSDs
+
+Setting C<$0> now works (as much as possible; see L<perlvar> for details).
+
+=item *
+
+Cygwin
+
+Numerous updates; currently synchronised with Cygwin 1.1.4.
+
+=item *
+
+Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
+
+=item *
+
+EPOC
+
+EPOC update after Perl 5.6.0. See README.epoc.
+
+=item *
+
+FreeBSD 3.*
+
+Perl now works on post-3.0 FreeBSDs.
+
+=item *
+
+HP-UX
+
+README.hpux updated; C<Configure -Duse64bitall> now almost works.
+
+=item *
+
+IRIX
+
+Numerous compilation flag and hint enhancements; accidental mixing
+of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
+
+=item *
+
+Linux
+
+=over 8
=item *
-Changed the POSIX character class C<[[:space:]]> to include the (very
-rare) vertical tabulator character. Added a new POSIX-ish character
-class C<[[:blank:]]> which stands for horizontal whitespace (currently,
-the space and the tabulator).
+Long doubles should now work (see INSTALL).
=item *
-$AUTOLOAD, sort(), lock(), and spawning subprocesses
-in multiple thread simultaneously are now thread-safe.
+Linux previously had problems related to sockaddrlen when using
+accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
+
+=back
=item *
-Allow read-only string on left hand side of non-modifying tr///.
+MacOS Classic
+
+Compilation of the standard Perl distribution in MacOS Classic should
+now work if you have the Metrowerks development environment and
+the missing Mac-specific toolkit bits. Contact the macperl mailing
+list for details.
=item *
-Several Unicode fixes (but still not perfect).
+MPE/iX
-BOMs (byte order marks) in the beginning of Perl files
-(scripts, modules) should now be transparently skipped.
-UTF16 encoded Perl files should now be read correctly.
+MPE/iX update after Perl 5.6.0. See README.mpeix.
-The character tables have been updated to new Unicode 3.0 features.
+=item *
-chr() for values greater than 127 now create utf8 when under use
-utf8.
+NetBSD/sparc
-Comparing with utf8 data does not magically upgrade non-utf8 data into
-utf8.
+Perl now works on NetBSD/sparc.
-C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
+=item *
-Concatenation with the C<.> operator or via variable interpolation,
-C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
-substitution with C<s///>, single-quoted UTF8, should now work--in
-theory.
+OS/2
-The C<tr///> operator now works I<slightly> better but is still rather
-broken. Note that the C<tr///CU> functionality has been removed (but
-see pack('U0', ...)).
+Now works with usethreads (see INSTALL).
-Zero entries were missing from the Unicode classes like C<IsDigit>.
+=item *
+
+Solaris
+
+64-bitness using the Sun Workshop compiler now works.
+
+=item *
+
+Tru64 (aka Digital UNIX, aka DEC OSF/1)
+
+The operating system version letter now recorded in $Config{osvers}.
+Allow compiling with gcc (previously explicitly forbidden). Compiling
+with gcc still not recommended because buggy code results, even with
+gcc 2.95.2.
+
+=item *
+
+Unicos
+
+Fixed various alignment problems that lead into core dumps either
+during build or later; no longer dies on math errors at runtime;
+now using full quad integers (64 bits), previously was using
+only 46 bit integers for speed.
+
+=item *
+
+VMS
+
+chdir() now works better despite a CRT bug; now works with MULTIPLICITY
+(see INSTALL); now works with Perl's malloc.
+
+The tainting of C<%ENV> elements via C<keys> or C<values> was previously
+unimplemented. It now works as documented.
+
+The C<waitpid> emulation has been improved. The worst bug (now fixed)
+was that a pid of -1 would cause a wildcard search of all processes on
+the system. The most significant enhancement is that we can now
+usually get the completion status of a terminated process.
+
+POSIX-style signals are now emulated much better on VMS versions prior
+to 7.0.
+
+The C<system> function and backticks operator have improved
+functionality and better error handling.
+
+=item *
+
+Windows
+
+=over 8
+
+=item *
+
+accept() no longer leaks memory.
+
+=item *
+
+Borland C++ v5.5 is now a supported compiler that can build Perl.
+However, the generated binaries continue to be incompatible with those
+generated by the other supported compilers (GCC and Visual C++).
+
+=item *
+
+Better chdir() return value for a non-existent directory.
+
+=item *
+
+Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
+
+=item *
+
+New %ENV entries now propagate to subprocesses.
+
+=item *
+
+Current directory entries in %ENV are now correctly propagated to child
+processes.
+
+=item *
+
+$ENV{LIB} now used to search for libs under Visual C.
+
+=item *
+
+fork() emulation has been improved in various ways, but still continues
+to be experimental. See L<perlfork> for known bugs and caveats.
+
+=item *
+
+A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
+
+=item *
+
+Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
+Other bugs in chdir() and Cwd::cwd() have also been fixed.
+
+=item *
+
+HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
+
+=item *
+
+The makefiles now provide a single switch to bulk-enable all the features
+enabled in ActiveState ActivePerl (a popular Win32 binary distribution).
+
+=item *
+
+Allow REG_EXPAND_SZ keys in the registry.
+
+=item *
+
+Can now send() from all threads, not just the first one.
+
+=item *
+
+Fake signal handling reenabled, bugs and all.
+
+=item *
+
+%SIG has been enabled under USE_ITHREADS, but its use is completely
+unsupported under all configurations.
+
+=item *
+
+Less stack reserved per thread so that more threads can run
+concurrently. (Still 16M per thread.)
+
+=item *
+
+C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
+(works better when perl is running as service).
+
+=item *
+
+Better UNC path handling under ithreads.
+
+=item *
+
+wait(), waitpid() and backticks now return the correct exit status under
+Windows 9x.
+
+=item *
+
+winsock handle leak fixed.
+
+=back
=back
=head1 New or Changed Diagnostics
+=over 4
+
+=item *
+
All regular expression compilation error messages are now hopefully
easier to understand both because the error message now comes before
the failed regex and because the point of failure is now clearly
-marked.
+marked by a C<E<lt>-- HERE> marker.
+
+=item *
The various "opened only for", "on closed", "never opened" warnings
drop the C<main::> prefix for filehandles in the C<main> package,
-for example C<STDIN> instead of <main::STDIN>.
+for example C<STDIN> instead of C<main::STDIN>.
-=over 4
+=item *
+
+The "Unrecognized escape" warning has been extended to include C<\8>,
+C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
=item *
-(perhaps you forgot to load "%s"?)
+Two new debugging options have been added: if you have compiled your
+Perl with debugging, you can use the -DT and -DR options to trace
+tokenising and to add reference counts to displaying variables,
+respectively.
-(F) This is an educated guess made in conjunction with the message
-"Can't locate object method \"%s\" via package \"%s\"". It often means
-that a method requires a package that has not been loaded.
+=item *
+
+If an attempt to use a (non-blessed) reference as an array index
+is made, a warning is given.
=item *
-Ambiguous range in transliteration operator
+C<push @a;> and C<unshift @a;> (with no values to push or unshift)
+now give a warning. This may be a problem for generated and evaled
+code.
+
+=item *
-(F) You wrote something like C<tr/a-z-0//> which doesn't mean anything at
-all. To include a C<-> character in a transliteration, put it either
-first or last. (In the past, C<tr/a-z-0//> was synonymous with
-C<tr/a-y//>, which was probably not what you would have expected.)
+If you try to L<perlfunc/pack> a number less than 0 or larger than 255
+using the C<"C"> format you will get an optional warning. Similarly
+for the C<"c"> format and a number less than -128 or more than 127.
=item *
-The "Unrecognized escape" warning has been extended to include C<\8>,
-C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
+Certain regex modifiers such as C<(?o)> make sense only if applied to
+the entire regex. You will an optional warning if you try to do otherwise.
+
+=item *
+
+Using arrays or hashes as references (e.g. C<< %foo->{bar} >>
+has been deprecated for a while. Now you will get an optional warning.
=back
=head1 Changed Internals
-=head2 apidoc
+=over 4
+
+=item *
perlapi.pod (a companion to perlguts) now attempts to document the
internal API.
-=head2 microperl
+=item *
-There is now a way to build a really minimal perl called microperl.
+You can now build a really minimal perl called microperl.
Building microperl does not require even running Configure;
C<make -f Makefile.micro> should be enough. Beware: microperl makes
many assumptions, some of which may be too bold; the resulting
-executable may crash or otherwise misbehave in wondrous ways. For
-careful hackers only.
+executable may crash or otherwise misbehave in wondrous ways.
+For careful hackers only.
-=head2 Publicise More Functions
+=item *
-Added rsignal(), whichsig(), do_join() to the publicised API.
+Added rsignal(), whichsig(), do_join(), op_clear, op_null,
+ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8
+interfaces to the publicised API. For the full list of the available
+APIs see L<perlapi>.
-=head2 Propagating Exception Objects via Perl_croak() IN XS code
+=item *
Made possible to propagate customised exceptions via croak()ing.
-=head2 UTF8 Interfaces
+=item *
+
+Now xsubs can have attributes just like subs. (Well, at least the
+built-in attributes.)
+
+=item *
+
+dTHR and djSP have been obsoleted; the former removed (because it's
+a no-op) and the latter replaced with dSP.
+
+=item *
+
+PERL_OBJECT has been completely removed.
+
+=item *
+
+The MAGIC constants (e.g. C<'P'>) have been macrofied
+(e.g. C<PERL_MAGIC_TIED>) for better source code readability
+and maintainability.
+
+=item *
+
+The regex compiler now maintains a structure that identifies nodes in
+the compiled bytecode with the corresponding syntactic features of the
+original regex expression. The information is attached to the new
+C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
+complete information.
+
+=item *
+
+The C code has been made much more C<gcc -Wall> clean. Some warning
+messages still remain in some platforms, so if you are compiling with
+gcc you may see some warnings about dubious practices. The warnings
+are being worked on.
+
+=item *
+
+F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
+
+=item *
+
+Documentation on how to use the Perl source repository has been added
+to F<Porting/repository.pod>.
+
+=item *
-Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
+There are now several profiling make targets.
-=head2 xsub attributes
+=back
+
+=head1 Security Vulnerability Closed
+
+(This change was already made in 5.7.0 but bears repeating here.)
+
+A potential security vulnerability in the optional suidperl component
+of Perl was identified in August 2000. suidperl is neither built nor
+installed by default. As of November 2001 the only known vulnerable
+platform is Linux, most likely all Linux distributions. CERT and
+various vendors and distributors have been alerted about the vulnerability.
+See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
+for more information.
+
+The problem was caused by Perl trying to report a suspected security
+exploit attempt using an external program, /bin/mail. On Linux
+platforms the /bin/mail program had an undocumented feature which
+when combined with suidperl gave access to a root shell, resulting in
+a serious compromise instead of reporting the exploit attempt. If you
+don't have /bin/mail, or if you have 'safe setuid scripts', or if
+suidperl is not installed, you are safe.
-Now xsubs can have attributes just like subs.
+The exploit attempt reporting feature has been completely removed from
+Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also
+from all the Perl 5.7 releases), so that particular vulnerability
+isn't there anymore. However, further security vulnerabilities are,
+unfortunately, always possible. The suidperl functionality is most
+probably going to be removed in Perl 5.10. In any case, suidperl
+should only be used by security experts who know exactly what they are
+doing and why they are using suidperl instead of some other solution
+such as sudo (see http://www.courtesan.com/sudo/).
+
+=head1 New Tests
+
+Several new tests have been added, especially for the F<lib>
+subsection. There are now about 34 000 individual tests (spread over
+about 530 test scripts), in the regression suite (5.6.1 has about
+11700 tests, in 258 test scripts) Many of the new tests are introduced
+by the new modules, but still in general Perl is now more thoroughly
+tested.
+
+Because of the large number of tests, running the regression suite
+will take considerably longer time than it used to: expect the suite
+to take up to 4-5 times longer to run than in perl 5.6. In a really
+fast machine you can hope to finish the suite in about 5 minutes
+(wallclock time).
+
+The tests are now reported in a different order than in earlier Perls.
+(This happens because the test scripts from under t/lib have been moved
+to be closer to the library/extension they are testing.)
=head1 Known Problems
-=head2 Unicode Support Still Far From Perfect
+=head2 AIX
-We're working on it. Stay tuned.
+=over 4
-=head2 EBCDIC Still A Lost Platform
+=item *
-The plan is to bring them back.
+In AIX 4.2 Perl extensions that use C++ functions that use statics
+may have problems in that the statics are not getting initialized.
+In newer AIX releases this has been solved by linking Perl with
+the libC_r library, but unfortunately in AIX 4.2 the said library
+has an obscure bug where the various functions related to time
+(such as time() and gettimeofday()) return broken values, and
+therefore in AIX 4.2 Perl is not linked against the libC_r.
-=head2 Building Extensions Can Fail Because Of Largefiles
+=item *
+
+vac 5.0.0.0 May Produce Buggy Code For Perl
+
+The AIX C compiler vac version 5.0.0.0 may produce buggy code,
+resulting in few random tests failing, but when the failing tests
+are run by hand, they succeed. We suggest upgrading to at least
+vac version 5.0.1.0, that has been known to compile Perl correctly.
+"lslpp -L|grep vac.C" will tell you the vac version.
+
+=back
+
+=head2 Amiga Perl Invoking Mystery
+
+One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
+works, but for example C<bin:perl -v> doesn't. The exact reason isn't
+known but the current suspect is the F<ixemul> library.
+
+=head2 lib/ftmp-security tests warn 'system possibly insecure'
+
+Don't panic. Read INSTALL 'make test' section instead.
+
+=head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
+
+The subtests 11 and 12 sometimes fail and sometimes work.
+
+=head2 HP-UX lib/io_multihomed Fails When LP64-Configured
+
+The lib/io_multihomed test may hang in HP-UX if Perl has been
+configured to be 64-bit. Because other 64-bit platforms do not hang in
+this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
+test attempts to create and connect to "multihomed" sockets (sockets
+which have multiple IP addresses).
+
+=head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
+
+If perl is configured with -Duse64bitall, the successful result of the
+subtest 10 of lib/posix may arrive before the successful result of the
+subtest 9, which confuses the test harness so much that it thinks the
+subtest 9 failed.
+
+=head2 Linux With Sfio Fails op/misc Test 48
+
+No known fix.
+
+=head2 Mac OS X
+
+The following tests are known to fail:
+
+ Failed Test Stat Wstat Total Fail Failed List of Failed
+ -------------------------------------------------------------------------
+ ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ??
+ ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65
+ ../ext/POSIX/t/posix.t 31 1 3.23% 10
+ ../lib/warnings.t 450 1 0.22% 316
+
+=head2 OS/390
+
+OS/390 has rather many test failures but the situation is actually
+better than it was in 5.6.0, it's just that so many new modules and
+tests have been added.
+
+ Failed Test Stat Wstat Total Fail Failed List of Failed
+ -----------------------------------------------------------------------------
+ ../ext/B/Deparse.t 14 1 7.14% 14
+ ../ext/B/Showlex.t 1 1 100.00% 1
+ ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
+ 600 602 604-610
+ ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
+ ../ext/POSIX/POSIX.t 29 1 3.45% 14
+ ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
+ ../lib/locale.t 129 33024 117 19 16.24% 99-117
+ ../lib/warnings.t 434 1 0.23% 75
+ ../lib/ExtUtils.t 27 1 3.70% 25
+ ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
+ ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
+ ../lib/User/pwent.t 9 1 11.11% 4
+ op/pat.t 660 6 0.91% 242-243 424-425
+ 626-627
+ op/split.t 0 9 ?? ?? % ??
+ op/taint.t 174 3 1.72% 156 162 168
+ op/tr.t 70 3 4.29% 50 58-59
+ Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
+
+=head2 op/sprintf tests 129 and 130
+
+The op/sprintf tests 129 and 130 are known to fail on some platforms.
+Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
+The failing platforms do not comply with the ANSI C Standard, line
+19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
+something other than "1" and "-1" when formatting 0.6 and -0.6 using
+the printf format "%.0f", most often they produce "0" and "-0".)
+
+=head2 Failure of Thread tests
+
+B<Note that support for 5.005-style threading remains experimental
+and practically unsupported.>
+
+The following tests are known to fail due to fundamental problems in
+the 5.005 threading implementation. These are not new failures--Perl
+5.005_0x has the same bugs, but didn't have these tests.
+
+ ext/List/Util/t/first 2
+ lib/autouse 4
+ ext/Thread/thr5005 19-20
+
+These failures are unlikely to get fixed.
+
+=head2 UNICOS
+
+=over 4
+
+=item *
+
+ext/POSIX/sigaction subtests 6 and 13 may fail.
-Certain extensions like mod_perl and BSD::Resource are known to have
-issues with `largefiles', a change brought by Perl 5.6.0 in where file
-offsets are by default 64 bits wide (assuming the platform supports
-such large files). Modules may fail to compile at all or compile and
-work incorrectly. Currently there is no good solution for the problem
-but Configure now stores the flags and libraries that affect the
-largefileness to the %Config hash, the extensions that are having
-problems can try configuring themselves without the largefileness.
-This is admittedly not a clean solution.
+=item *
+
+lib/ExtUtils may spuriously claim that subtest 28 failed,
+which is interesting since the test only has 27 tests.
+
+=item *
+
+Numerous numerical test failures
+
+ op/numconvert 209,210,217,218
+ op/override 7
+ ext/Time/HiRes/HiRes 9
+ lib/Math/BigInt/t/bigintpm 1145
+ lib/Math/Trig 25
+
+These tests fail because of yet unresolved floating point inaccuracies.
+
+=back
+
+=head2 UNICOS/mk
+
+The io/fs test #31 is failing because in UNICOS/mk truncate() cannot
+be used to grow the size of filehandles, only to reduce the size.
+The workaround is to truncate files instead of filehandles.
+
+=head2 UTS
+
+There are a few known test failures, see L<perluts>.
+
+=head2 VMS
+
+There is one known test failure with a default configuration:
-=head1 Obsolete Diagnostics
+ [.run]switches..........................FAILED on test 1
+
+=head2 Win32
+
+In multi-CPU boxes there are some problems with the I/O buffering:
+some output may appear twice.
+
+=head2 Localising a Tied Variable Leaks Memory
+
+ use Tie::Hash;
+ tie my %tie_hash => 'Tie::StdHash';
+
+ ...
+
+ local($tie_hash{Foo}) = 1; # leaks
+
+Code like the above is known to leak memory every time the local()
+is executed.
+
+=head2 Localising Tied Arrays and Hashes Is Broken
+
+ local %tied_array;
+
+doesn't work as one would expect: the old value is restored
+incorrectly.
+
+=head2 Self-tying of Arrays and Hashes Is Forbidden
+
+Self-tying of arrays and hashes is broken in rather deep and
+hard-to-fix ways. As a stop-gap measure to avoid people from getting
+frustrated at the mysterious results (core dumps, most often) it is
+for now forbidden (you will get a fatal error even from an attempt).
+
+=head2 Building Extensions Can Fail Because Of Largefiles
+
+Some extensions like mod_perl are known to have issues with
+`largefiles', a change brought by Perl 5.6.0 in which file offsets
+default to 64 bits wide, where supported. Modules may fail to compile
+at all or compile and work incorrectly. Currently there is no good
+solution for the problem, but Configure now provides appropriate
+non-largefile ccflags, ldflags, libswanted, and libs in the %Config
+hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
+having problems can try configuring themselves without the
+largefileness. This is admittedly not a clean solution, and the
+solution may not even work at all. One potential failure is whether
+one can (or, if one can, whether it's a good idea) link together at
+all binaries with different ideas about file offsets, all this is
+platform-dependent.
+
+=head2 Unicode Support on EBCDIC Still Spotty
+
+Though mostly working, Unicode support still has problem spots on
+EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}>
+regular expression constructs for code points less than 256: the
+pP are testing for Unicode code points, not knowing about EBCDIC.
+
+=head2 The Compiler Suite Is Still Experimental
+
+The compiler suite is slowly getting better but it continues to be
+highly experimental. Use in production environments is discouraged.
+
+=head2 The Long Double Support Is Still Experimental
+
+The ability to configure Perl's numbers to use "long doubles",
+floating point numbers of hopefully better accuracy, is still
+experimental. The implementations of long doubles are not yet
+widespread and the existing implementations are not quite mature
+or standardised, therefore trying to support them is a rare
+and moving target. The gain of more precision may also be offset
+by slowdown in computations (more bits to move around, and the
+operations are more likely to be executed by less optimised
+libraries).
+
+=head2 Seen In Perl 5.7 But Gone Now
+
+C<Time::Piece> (previously known as C<Time::Object>) was removed
+because it was felt that it didn't have enough value in it to be a
+core module. It is still a useful module, though, and is available
+from the CPAN.
=head1 Reporting Bugs
If you find what you think is a bug, you might check the articles
recently posted to the comp.lang.perl.misc newsgroup and the perl
bug database at http://bugs.perl.org. There may also be
-information at http://www.perl.com/perl/, the Perl Home Page.
+information at http://www.perl.com/, the Perl Home Page.
If you believe you have an unreported bug, please run the B<perlbug>
program included with your release. Be sure to trim your bug down
=head1 HISTORY
-Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
-from The Perl Porters and Perl Users submitting feedback and patches.
-
-Send omissions or corrections to <F<perlbug@perl.org>>.
+Written by Jarkko Hietaniemi <F<jhi@iki.fi>>.
=cut
https://perl5.git.perl.org / perl5.git / blobdiff