-=head1 NAME
-
-perldelta - what is new for perl v5.8.0
-
-=head1 DESCRIPTION
-
-This document describes differences between the 5.6.0 release and
-the 5.8.0 release.
-
-Many of the bug fixes in 5.8.0 were already seen in the 5.6.1
-maintenance release since the two releases were kept closely
-coordinated (while 5.8.0 was still called 5.7.something).
-
-Changes that were integrated into the 5.6.1 release are marked C<[561]>.
-Many of these changes have been further developed since 5.6.1 was released,
-those are marked C<[561+]>.
-
-You can see the list of changes in the 5.6.1 release (both from the
-5.005_03 release and the 5.6.0 release) by reading L<perl561delta>.
-
-=head1 Highlights In 5.8.0
-
-=over 4
-
-=item *
-
-Better Unicode support
-
-=item *
-
-New IO Implementation
-
-=item *
-
-New Thread Implementation
-
-=item *
-
-Better Numeric Accuracy
-
-=item *
-
-Safe Signals
-
-=item *
-
-Many New Modules
-
-=item *
-
-More Extensive Regression Testing
-
-=back
-
-=head1 Incompatible Changes
-
-=head2 Binary Incompatibility
-
-B<Perl 5.8 is not binary compatible with earlier releases of Perl.>
-
-B<You have to recompile your XS modules.>
-
-(Pure Perl modules should continue to work.)
-
-The major reason for the discontinuity is the new IO architecture
-called PerlIO. PerlIO is the default configuration because without
-it many new features of Perl 5.8 cannot be used. In other words:
-you just have to recompile your modules containing XS code, sorry
-about that.
-
-In future releases of Perl, non-PerlIO aware XS modules may become
-completely unsupported. This shouldn't be too difficult for module
-authors, however: PerlIO has been designed as a drop-in replacement
-(at the source code level) for the stdio interface.
-
-Depending on your platform, there are also other reasons why
-we decided to break binary compatibility, please read on.
-
-=head2 64-bit platforms and malloc
-
-If your pointers are 64 bits wide, the Perl malloc is no longer being
-used because it does not work well with 8-byte pointers. Also,
-usually the system mallocs on such platforms are much better optimized
-for such large memory models than the Perl malloc. Some memory-hungry
-Perl applications like the PDL don't work well with Perl's malloc.
-Finally, other applications than Perl (such as mod_perl) tend to prefer
-the system malloc. Such platforms include Alpha and 64-bit HPPA,
-MIPS, PPC, and Sparc.
-
-=head2 AIX Dynaloading
-
-The AIX dynaloading now uses in AIX releases 4.3 and newer the native
-dlopen interface of AIX instead of the old emulated interface. This
-change will probably break backward compatibility with compiled
-modules. The change was made to make Perl more compliant with other
-applications like mod_perl which are using the AIX native interface.
-
-=head2 Attributes for C<my> variables now handled at run-time.
-
-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).
-
-=head2 Socket Extension Dynamic in VMS
-
-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.
-
-=head2 IEEE-format Floating Point Default on OpenVMS Alpha
-
-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.
-
-=head2 New Unicode Properties
-
-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.
-
-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>).
-
-A number of other properties are now supported, including C<\p{L&}>,
-C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> [561] and
-C<\p{SpacePerl}> [561] (along with their C<\P{...}> versions, of course).
-See L<perlunicode> for details, and more additions.
-
-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>).
-
-=head2 REF(...) Instead Of SCALAR(...)
-
-A reference to a reference now stringifies as "REF(0x81485ec)" instead
-of "SCALAR(0x81485ec)" in order to be more consistent with the return
-value of ref().
-
-=head2 pack/unpack D/F recycled
-
-The undocumented pack/unpack template letters D/F have been recycled
-for better use: now they stand for long double (if supported by the
-platform) and NV (Perl internal floating point type). (They used
-to be aliases for d/f, but you never knew that.)
-
-=head2 Deprecations
-
-=over 4
-
-=item *
-
-The semantics of bless(REF, REF) were unclear and until someone proves
-it to make some sense, it is forbidden.
-
-=item *
-
-The obsolete chat2 library that should never have been allowed
-to escape the laboratory has been decommissioned.
-
-=item *
-
-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 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 *
-
-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 *
-
-The list of filenames from glob() (or <...>) is now by default sorted
-alphabetically to be csh-compliant (which is what happened before
-in most UNIX platforms). (bsd_glob() does still sort platform
-natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) [561]
-
-=item *
-
-Spurious syntax errors generated in certain situations, when glob()
-caused File::Glob to be loaded for the first time, have been fixed. [561]
-
-=item *
-
-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 *
-
-lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
-In future releases this may become a fatal error.
-
-=item *
-
-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 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 *
-
-In future releases, non-PerlIO aware XS modules may become completely
-unsupported. Since PerlIO is a drop-in replacement for stdio at the
-source code level, this shouldn't be that drastic a change.
-
-=item *
-
-The PerlIO C<:raw> discipline (as described in Camel III) is deprecated
-because its definition (as either the discipline version of C<binmode(FH)>
-or as the opposite of C<:crlf>) didn't really work: most importantly
-because turning off "clrfness" is not enough to make a stream truly
-binary. Instead of C<:raw> use one of the following: C<open(..., ':bytes')>,
-C<binmode(FH)>, C<sysopen()> + C<sysread()>.
-
-=item *
-
-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. The I<restricted hashes> interface is expected to
-be the replacement interface (see L<Hash::Util>).
-
-=item *
-
-The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated.
-
-=item *
-
-After years of trying, suidperl is considered to be too complex to
-ever be considered truly secure. The suidperl functionality is likely
-to be removed in a future release.
-
-=item *
-
-The 5.005 threads model (module C<Thread>) is deprecated and expected
-to be removed in Perl 5.10. Multithreaded code should be migrated to
-the new ithreads model (see L<threads>, L<threads::shared> and
-L<perlthrtut>).
-
-=item *
-
-The long deprecated uppercase aliases for the string comparison
-operators (EQ, NE, LT, LE, GE, GT) have now been removed.
-
-=item *
-
-The tr///C and tr///U features have been removed and will not return;
-the interface was a mistake. Sorry about that. For similar
-functionality, see pack('U0', ...) and pack('C0', ...). [561]
-
-=item *
-
-Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)".
-The prototypes are now checked better at compile-time for invalid
-syntax. An optional warning is generated ("Illegal character in
-prototype...") but this may be upgraded to a fatal error in a future
-release.
-
-=item *
-
-The C<exec LIST> and C<system LIST> operations will produce fatal
-errors on tainted data in some future release.
-
-=item *
-
-The existing behaviour when localising tied arrays and hashes is wrong,
-and will be changed in a future release, so do not rely on the existing
-behaviour. See L<"Localising Tied Arrays and Hashes Is Broken">.
-
-=back
-
-=head1 Core Enhancements
-
-=head2 PerlIO is Now The Default
-
-=over 4
-
-=item *
-
-IO is now by default done via PerlIO rather than system's "stdio".
-PerlIO allows "layers" to be "pushed" onto a file handle to alter the
-handle's behaviour. Layers can be specified at open time via 3-arg
-form of open:
-
- open($fh,'>:crlf :utf8', $path) || ...
-
-or on already opened handles via extended C<binmode>:
-
- binmode($fh,':encoding(iso-8859-7)');
-
-The built-in layers are: unix (low level read/write), stdio (as in
-previous Perls), perlio (re-implementation of stdio buffering in a
-portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
-but available on any platform). A mmap layer may be available if
-platform supports it (mostly UNIXes).
-
-Layers to be applied by default may be specified via the 'open' pragma.
-
-See L</"Installation and Configuration Improvements"> for the effects
-of PerlIO on your architecture name.
-
-=item *
-
-If your platform supports fork(), you can use the list form of C<open>
-for pipes:
-
- open KID_PS, "-|", "ps", "aux" or die $!;
-
-forks the ps(1) command (without spawning a shell, as there are more
-than three arguments to open()), and reads its standard output via the
-C<KID_PS> filehandle.
-
-=item *
-
-File handles can be marked as accepting Perl's internal encoding of Unicode
-(UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
-
- open($fh,">:utf8","Uni.txt");
-
-Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
-for you since it's not UTF-8 what you will be getting but instead
-UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
-http://www.unicode.org/unicode/reports/tr16/ for more information.
-In future releases this naming may change. See L<perluniintro>
-for more information about UTF-8.
-
-=item *
-
-If your environment variables (LC_ALL, LC_CTYPE, LANG, LANGUAGE) look
-like you want to use UTF-8 (any of the the variables match C</utf-?8/i>),
-your STDIN, STDOUT, STDERR handles and the default open discipline
-(see L<open>) are marked as UTF-8. (This feature, like other new
-features that combine Unicode and I/O, work only if you are using
-PerlIO, but that's is the default.)
-
-Note that after this Perl really does assume that everything is UTF-8:
-for example if some input handle is not, Perl will probably very soon
-complain about the input data like this "Malformed UTF-8 ..." since
-any old eight-bit data is not legal UTF-8.
-
-Note for code authors: if you want to enable your users to use UTF-8
-as their default encoding but in your code still have eight-bit I/O streams
-(such as images or zip files), you need to explicitly open() or binmode()
-with C<:bytes> (see L<perlfunc/open> and L<perlfunc/binmode>), or you
-can just use C<binmode(FH)> (nice for pre-5.8.0 backward compatibility).
-
-=item *
-
-File handles can translate character encodings from/to Perl's internal
-Unicode form on read/write via the ":encoding()" layer.
-
-=item *
-
-File handles can be opened to "in memory" files held in Perl scalars via:
-
- open($fh,'>', \$variable) || ...
-
-=item *
-
-Anonymous temporary files are available without need to
-'use FileHandle' or other module via
-
- open($fh,"+>", undef) || ...
-
-That is a literal undef, not an undefined value.
-
-=item *
-
-The list form of C<open> is now implemented for pipes (at least on UNIX):
-
- open($fh,"-|", 'cat', '/etc/motd')
-
-creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
-the child process.
-
-=item *
-
-If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG)
-contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
-the default encoding of your STDIN, STDOUT, and STDERR, and of
-B<any subsequent file open>, is UTF-8.
-
-=back
-
-=head2 Restricted Hashes
-
-A restricted hash is restricted to a certain set of keys, no keys
-outside the set can be added. Also individual keys can be restricted
-so that the key cannot be deleted and the value cannot be changed.
-No new syntax is involved: the Hash::Util module is the interface.
-
-=head2 Safe Signals
-
-Perl used to be fragile in that signals arriving at inopportune moments
-could corrupt Perl's internal state. Now Perl postpones handling of
-signals until it's safe (between opcodes).
-
-This change may have surprising side effects because signals no longer
-interrupt Perl instantly. Perl will now first finish whatever it was
-doing, like finishing an internal operation (like sort()) or an
-external operation (like an I/O operation), and only then look at any
-arrived signals (and before starting the next operation). No more corrupt
-internal state since the current operation is always finished first,
-but the signal may take more time to get heard. Note that breaking
-out from potentially blocking operations should still work, though.
-
-=head2 Unicode Overhaul
-
-Unicode in general should be now much more usable than in Perl 5.6.0
-(or even in 5.6.1). Unicode can be used in hash keys, Unicode in
-regular expressions should work now, Unicode in tr/// should work now,
-Unicode in I/O should work now. See L<perluniintro> for introduction
-and L<perlunicode> for details.
-
-=over 4
-
-=item *
-
-The Unicode Character Database coming with Perl has been upgraded
-to Unicode 3.2.0. For more information, see http://www.unicode.org/ .
-[561+] (5.6.1 has UCD 3.0.1.)
-
-=item *
-
-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.
-
-=item *
-
-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.)
-
-See "New Unicode Properties" earlier in this document for additional
-information on changes with Unicode properties.
-
-=back
-
-=head2 Understanding of Numbers
-
-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.
-
-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.)
-
-=head2 Arrays now always interpolate into double-quoted strings [561]
-
-In double-quoted strings, arrays now interpolate, no matter what. The
-behavior in earlier versions of perl 5 was that arrays would interpolate
-into strings if the array had been mentioned before the string was
-compiled, and otherwise Perl would raise a fatal compile-time error.
-In versions 5.000 through 5.003, the error was
-
- Literal @example now requires backslash
-
-In versions 5.004_01 through 5.6.0, the error was
-
- In string, @example now must be written as \@example
-
-The idea here was to get people into the habit of writing
-C<"fred\@example.com"> when they wanted a literal C<@> sign, just as
-they have always written C<"Give me back my \$5"> when they wanted a
-literal C<$> sign.
-
-Starting with 5.6.1, when Perl now sees an C<@> sign in a
-double-quoted string, it I<always> attempts to interpolate an array,
-regardless of whether or not the array has been used or declared
-already. The fatal error has been downgraded to an optional warning:
-
- Possible unintended interpolation of @example in string
-
-This warns you that C<"fred@example.com"> is going to turn into
-C<fred.com> if you don't backslash the C<@>.
-See http://www.plover.com/~mjd/perl/at-error.html for more details
-about the history here.
-
-=head2 Miscellaneous Changes
-
-=over 4
-
-=item *
-
-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 *
-
-The $Config{byteorder} (and corresponding BYTEORDER in config.h) was
-previously wrong in platforms if sizeof(long) was 4, but sizeof(IV)
-was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321),
-but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321).
-(This problem didn't affect Windows platforms.)
-
-Also, $Config{byteorder} is now computed dynamically--this is more
-robust with "fat binaries" where an executable image contains binaries
-for more than one binary platform, and when cross-compiling.
-
-=item *
-
-C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
-in multiple arguments.)
-
-=item *
-
-C<do> followed by a bareword now ensures that this bareword isn't
-a keyword (to avoid a bug where C<do q(foo.pl)> tried to call a
-subroutine called C<q>). This means that for example instead of
-C<do format()> you must write C<do &format()>.
-
-=item *
-
-The builtin dump() now gives an optional warning
-C<dump() better written as CORE::dump()>,
-meaning that by default C<dump(...)> is resolved as the builtin
-dump() which dumps core and aborts, not as (possibly) user-defined
-C<sub dump>. To call the latter, qualify the call as C<&dump(...)>.
-(The whole dump() feature is to considered deprecated, and possibly
-removed/changed in future releases.)
-
-=item *
-
-chomp() and chop() are now overridable. Note, however, that their
-prototype (as given by C<prototype("CORE::chomp")> is undefined,
-because it cannot be expressed and therefore one cannot really write
-replacements to override these builtins.
-
-=item *
-
-END blocks are now run even if you exit/die in a BEGIN block.
-Internally, the execution of END blocks is now controlled by
-PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
-behaviour for Perl embedders. This will default in 5.10. See
-L<perlembed>.
-
-=item *
-
-Formats now support zero-padded decimal fields.
-
-=item *
-
-Lvalue subroutines can now return C<undef> in list context. However,
-the lvalue subroutine feature still remains experimental. [561+]
-
-=item *
-
-A lost warning "Can't declare ... dereference in my" has been
-restored (Perl had it earlier but it became lost in later releases.)
-
-=item *
-
-A new special regular expression variable has been introduced:
-C<$^N>, which contains the most-recently closed group (submatch).
-
-=item *
-
-C<no Module;> does not produce an error even if Module does not have an
-unimport() method. This parallels the behavior of C<use> vis-a-vis
-C<import>. [561]
-
-=item *
-
-The numerical comparison operators return C<undef> if either operand
-is a NaN. Previously the behaviour was unspecified.
-
-=item *
-
-C<our> can now have an experimental optional attribute C<unique> that
-affects how global variables are shared among multiple interpreters,
-see L<perlfunc/our>.
-
-=item *
-
-The following builtin functions are now overridable: each(), keys(),
-pop(), push(), shift(), splice(), unshift(). [561]
-
-=item *
-
-C<pack() / unpack()> can now group template letters with C<()> and then
-apply repetition/count modifiers on the groups.
-
-=item *
-
-C<pack() / unpack()> can now process the Perl internal numeric types:
-IVs, UVs, NVs-- and also long doubles, if supported by the platform.
-The template letters are C<j>, C<J>, C<F>, and C<D>.
-
-=item *
-
-C<pack('U0a*', ...)> can now be used to force a string to UTF8.
-
-=item *
-
-my __PACKAGE__ $obj now works. [561]
-
-=item *
-
-POSIX::sleep() now returns the number of I<unslept> seconds
-(as the POSIX standard says), as opposed to CORE::sleep() which
-returns the number of slept seconds.
-
-=item *
-
-The printf() and sprintf() now support parameter reordering using the
-C<%\d+\$> and C<*\d+\$> syntaxes. For example
-
- print "%2\$s %1\$s\n", "foo", "bar";
-
-will print "bar foo\n". This feature helps in writing
-internationalised software, and in general when the order
-of the parameters can vary.
-
-=item *
-
-The (\&) prototype now works properly. [561]
-
-=item *
-
-prototype(\[$@%&]) is now available to implicitly create references
-(useful for example if you want to emulate the tie() interface).
-
-=item *
-
-A new command-line option, C<-t> is available. It is the
-little brother of C<-T>: instead of dying 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 *
-
-In other taint news, the C<exec LIST> and C<system LIST> have now been
-considered too risky (think C<exec @ARGV>: it can start any program
-with any arguments), and now the said forms cause a warning under
-lexical warnings. You should carefully launder the arguments to
-guarantee their validity. In future releases of Perl the forms will
-become fatal errors so consider starting laundering now.
-
-=item *
-
-Tied hash interfaces are now required to have the EXISTS and DELETE
-methods (either own or inherited).
-
-=item *
-
-If tr/// is just counting characters, it doesn't attempt to
-modify its target.
-
-=item *
-
-untie() will now call an UNTIE() hook if it exists. See L<perltie>
-for details. [561]
-
-=item *
-
-L<utime> now supports C<utime undef, undef, @files> to change the
-file timestamps to the current time.
-
-=item *
-
-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 *
-
-Rather than relying on C's argv[0] (which may not contain a full pathname)
-where possible $^X is now set by asking the operating system.
-(eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD)
-
-=item *
-
-A new variable, C<${^TAINT}>, indicates whether taint mode is enabled.
-
-=item *
-
-You can now override the readline() builtin, and this overrides also
-the <FILEHANDLE> angle bracket operator.
-
-=item *
-
-The command-line options -s and -F are now recognized on the shebang
-(#!) line.
-
-=item *
-
-Use of the C</c> match modifier without an accompanying C</g> modifier
-elicits a new warning: C<Use of /c modifier is meaningless without /g>.
-
-Use of C</c> in substitutions, even with C</g>, elicits
-C<Use of /c modifier is meaningless in s///>.
-
-Use of C</g> with C<split> elicits C<Use of /g modifier is meaningless
-in split>.
-
-=item *
-
-Support for the C<CLONE> special subroutine had been added.
-With ithreads, when a new thread is created, all Perl data is cloned,
-however non-Perl data cannot be cloned automatically. In C<CLONE> you
-can do whatever you need to do, like for example handle the cloning of
-non-Perl data, if necessary. C<CLONE> will be executed once for every
-package that has it defined or inherited. It will be called in the
-context of the new thread, so all modifications are made in the new area.
-
-See L<perlmod>
-
-=back
-
-=head1 Modules and Pragmata
-
-=head2 New Modules and Pragmata
-
-=over 4
-
-=item *
-
-C<Attribute::Handlers>, originally by Damian Conway and now maintained
-by Arthur Bergman, allows a class to define attribute handlers.
-
- package MyPack;
- use Attribute::Handlers;
- sub Wolf :ATTR(SCALAR) { print "howl!\n" }
-
- # later, in some package using or inheriting from MyPack...
-
- my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called
-
-Both variables and routines can have attribute handlers. Handlers can
-be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the
-exact compilation phase (BEGIN, CHECK, INIT, or END).
-See L<Attribute::Handlers>.
-
-=item *
-
-C<B::Concise>, by Stephen McCamant, is a new compiler backend for
-walking the Perl syntax tree, printing concise info about ops.
-The output is highly customisable. See L<B::Concise>. [561+]
-
-=item *
-
-The new bignum, bigint, and bigrat pragmas, by Tels, implement
-transparent bignum support (using the Math::BigInt, Math::BigFloat,
-and Math::BigRat backends).
-
-=item *
-
-C<Class::ISA>, by Sean Burke, is a module for reporting the search
-path for a class's ISA tree. See L<Class::ISA>.
-
-=item *
-
-C<Cwd> now has a split personality: if possible, an XS extension is
-used, (this will hopefully be faster, more secure, and more robust)
-but if not possible, the familiar Perl implementation is used.
-
-=item *
-
-C<Devel::PPPort>, originally by Kenneth Albanowski and now
-maintained by Paul Marquess, has been added. It is primarily used
-by C<h2xs> to enhance portability of XS modules between different
-versions of Perl. See L<Devel::PPPort>.
-
-=item *
-
-C<Digest>, frontend module for calculating digests (checksums), from
-Gisle Aas, has been added. See L<Digest>.
-
-=item *
-
-C<Digest::MD5> for calculating MD5 digests (checksums) as defined in
-RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>.
-
- use Digest::MD5 'md5_hex';
-
- $digest = md5_hex("Thirsty Camel");
-
- print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
-
-NOTE: the C<MD5> backward compatibility module is deliberately not
-included since its further use is discouraged.
-
-=item *
-
-C<Encode>, originally by Nick Ing-Simmons and now maintained by Dan
-Kogai, provides a mechanism to translate between different character
-encodings. Support for Unicode, ISO-8859-1, and ASCII are compiled in
-to the module. Several other encodings (like the rest of the
-ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese,
-Japanese, and Korean encodings) are included and can be loaded at
-runtime. (For space considerations, the largest Chinese encodings
-have been separated into their own CPAN module, Encode::HanExtra,
-which Encode will use if available). See L<Encode>.
-
-Any encoding supported by Encode module is also available to the
-":encoding()" layer if PerlIO is used.
-
-=item *
-
-C<Hash::Util> is the interface to the new I<restricted hashes>
-feature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and
-Michael Schwern.) See L<Hash::Util>.
-
-=item *
-
-C<I18N::Langinfo> can be used to query locale information.
-See L<I18N::Langinfo>.
-
-=item *
-
-C<I18N::LangTags>, by Sean Burke, has functions for dealing with
-RFC3066-style language tags. See L<I18N::LangTags>.
-
-=item *
-
-C<ExtUtils::Constant>, by Nicholas Clark, is a new tool for extension
-writers for generating XS code to import C header constants.
-See L<ExtUtils::Constant>.
-
-=item *
-
-C<Filter::Simple>, by Damian Conway, is an easy-to-use frontend to
-Filter::Util::Call. See L<Filter::Simple>.
-
- # in MyFilter.pm:
-
- package MyFilter;
-
- use Filter::Simple sub {
- while (my ($from, $to) = splice @_, 0, 2) {
- s/$from/$to/g;
- }
- };
-
- 1;
-
- # in user's code:
-
- use MyFilter qr/red/ => 'green';
-
- print "red\n"; # this code is filtered, will print "green\n"
- print "bored\n"; # this code is filtered, will print "bogreen\n"
-
- no MyFilter;
-
- print "red\n"; # this code is not filtered, will print "red\n"
-
-=item *
-
-C<File::Temp>, by Tim Jenness, allows one to create temporary files
-and directories in an easy, portable, and secure way. See L<File::Temp>.
-[561+]
-
-=item *
-
-C<Filter::Util::Call>, by Paul Marquess, provides you with the
-framework to write I<source filters> in Perl. For most uses, the
-frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>.
-
-=item *
-
-C<if>, by Ilya Zakharevich, is a new pragma for conditional inclusion
-of modules.
-
-=item *
-
-L<libnet>, by Graham Barr, is a collection of perl5 modules related
-to network programming. See L<Net::FTP>, L<Net::NNTP>, L<Net::Ping>
-(not part of libnet, but related), L<Net::POP3>, L<Net::SMTP>,
-and L<Net::Time>.
-
-Perl installation leaves libnet unconfigured; use F<libnetcfg>
-to configure it.
-
-=item *
-
-C<List::Util>, by Graham Barr, is a selection of general-utility
-list subroutines, such as sum(), min(), first(), and shuffle().
-See L<List::Util>.
-
-=item *
-
-C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency>
-C<Locale::Language>, and L<Locale::Script>, by Neil Bowers, have
-been added. They provide the codes for various locale standards, such
-as "fr" for France, "usd" for US Dollar, and "ja" for Japanese.
-
- use Locale::Country;
-
- $country = code2country('jp'); # $country gets 'Japan'
- $code = country2code('Norway'); # $code gets 'no'
-
-See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
-and L<Locale::Language>.
-
-=item *
-
-C<Locale::Maketext>, by Sean Burke, is a localization framework. See
-L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an
-article about software localization, originally published in The Perl
-Journal #13, and republished here with kind permission.
-
-=item *
-
-C<Math::BigRat> for big rational numbers, to accompany Math::BigInt and
-Math::BigFloat, from Tels. See L<Math::BigRat>.
-
-=item *
-
-C<Memoize> can make your functions faster by trading space for time,
-from Mark-Jason Dominus. See L<Memoize>.
-
-=item *
-
-C<MIME::Base64>, by Gisle Aas, allows you to encode data in base64,
-as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail
-Extensions)>.
-
- use MIME::Base64;
-
- $encoded = encode_base64('Aladdin:open sesame');
- $decoded = decode_base64($encoded);
-
- print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
-
-See L<MIME::Base64>.
-
-=item *
-
-C<MIME::QuotedPrint>, by Gisle Aas, allows you to encode data
-in quoted-printable encoding, as defined in RFC 2045 - I<MIME
-(Multipurpose Internet Mail Extensions)>.
-
- use MIME::QuotedPrint;
-
- $encoded = encode_qp("Smiley in Unicode: \x{263a}");
- $decoded = decode_qp($encoded);
-
- print $encoded, "\n"; # "Smiley in Unicode: =263A"
-
-MIME::QuotedPrint has been enhanced to provide the basic methods
-necessary to use it with PerlIO::Via as in :
-
- use MIME::QuotedPrint;
- open($fh,">Via(MIME::QuotedPrint)",$path);
-
-See L<MIME::QuotedPrint>.
-
-=item *
-
-C<NEXT>, by Damian Conway, is a pseudo-class for method redispatch.
-See L<NEXT>.
-
-=item *
-
-C<open> is a new pragma for setting the default I/O disciplines
-for open().
-
-=item *
-
-C<PerlIO::Scalar>, by Nick Ing-Simmons, provides the implementation
-of IO to "in memory" Perl scalars as discussed above. It also serves
-as an example of a loadable PerlIO layer. Other future possibilities
-include PerlIO::Array and PerlIO::Code. See L<PerlIO::Scalar>.
-
-=item *
-
-C<PerlIO::Via>, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
-PerlIO layer functionality provided by a class (typically implemented
-in perl code).
-
- use MIME::QuotedPrint;
- open($fh,">Via(MIME::QuotedPrint)",$path);
-
-This will automatically convert everything output to C<$fh>
-to Quoted-Printable. See L<PerlIO::Via>.
-
-=item *
-
-C<Pod::ParseLink>, by Russ Allbery, has been added,
-to parse LZ<><> links in pods as described in the new
-perlpodspec.
-
-=item *
-
-C<Pod::Text::Overstrike>, by Joe Smith, has been added.
-It converts POD data to formatted overstrike text.
-See L<Pod::Text::Overstrike>. [561+]
-
-=item *
-
-C<Scalar::Util> is a selection of general-utility scalar subroutines,
-such as blessed(), reftype(), and tainted(). See L<Scalar::Util>.
-
-=item *
-
-C<sort> is a new pragma for controlling the behaviour of sort().
-
-=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. Because in effect Storable does serialisation
-of Perl data structues, with it you can also clone deep, hierarchical
-datastructures. Storable was originally created by Raphael Manfredi,
-but it is now maintained by Abhijit Menon-Sen. Storable has been
-enhanced to understand the two new hash features, Unicode keys and
-restricted hashes. See L<Storable>.
-
-=item *
-
-C<Switch>, by Damian Conway, has been added. Just by saying
-
- use Switch;
-
-you have C<switch> and C<case> available in Perl.
-
- use Switch;
-
- switch ($val) {
-
- case 1 { print "number 1" }
- case "a" { print "string a" }
- case [1..10,42] { print "number in list" }
- case (@array) { print "number in list" }
- case /\w+/ { print "pattern" }
- case qr/\w+/ { print "pattern" }
- case (%hash) { print "entry in hash" }
- case (\%hash) { print "entry in hash" }
- case (\&sub) { print "arg to subroutine" }
- else { print "previous case not true" }
- }
-
-See L<Switch>.
-
-=item *
-
-C<Test::More>, by Michael Schwern, is yet another framework for writing
-test scripts, more extensive than Test::Simple. See L<Test::More>.
-
-=item *
-
-C<Test::Simple>, by Michael Schwern, has basic utilities for writing
-tests. See L<Test::Simple>.
-
-=item *
-
-C<Text::Balanced>, by Damian Conway, has been added, for extracting
-delimited text sequences from strings.
-
- use Text::Balanced 'extract_delimited';
-
- ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
-
-$a will be "'never say never'", $b will be ', he never said'.
-
-In addition to extract_delimited(), there are also extract_bracketed(),
-extract_quotelike(), extract_codeblock(), extract_variable(),
-extract_tagged(), extract_multiple(), gen_delimited_pat(), and
-gen_extract_tagged(). With these, you can implement rather advanced
-parsing algorithms. See L<Text::Balanced>.
-
-=item *
-
-C<threads>, by Arthur Bergman, is an interface to interpreter threads.
-Interpreter threads (ithreads) is the new thread model introduced in
-Perl 5.6 but only available as an internal interface for extension
-writers (and for Win32 Perl for C<fork()> emulation). See L<threads>,
-L<threads::shared>, and L<perlthrtut>.
-
-=item *
-
-C<threads::shared>, by Arthur Bergman, allows data sharing for
-interpreter threads. 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 *
-
-C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the
-lines of a file. See L<Tie::File>.
-
-=item *
-
-C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes.
-See L<Tie::Memoize>.
-
-=item *
-
-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>.
-
-=item *
-
-C<Time::HiRes>, by Douglas E. Wegscheid, provides high resolution
-timing (ualarm, usleep, and gettimeofday). See L<Time::HiRes>.
-
-=item *
-
-C<Unicode::UCD> offers a querying interface to the Unicode Character
-Database. See L<Unicode::UCD>.
-
-=item *
-
-C<Unicode::Collate>, by SADAHIRO Tomoyuki, implements the UCA
-(Unicode Collation Algorithm) for sorting Unicode strings.
-See L<Unicode::Collate>.
-
-=item *
-
-C<Unicode::Normalize>, by SADAHIRO Tomoyuki, implements the various
-Unicode normalization forms. See L<Unicode::Normalize>.
-
-=item *
-
-C<XS::APItest>, by Tim Jenness, is a test extension that exercises XS
-APIs. Currently only C<printf()> is tested: how to output various
-basic data types from XS.
-
-=item *
-
-C<XS::Typemap>, by Tim Jenness, is a test extension that exercises
-XS typemaps. Nothing gets installed, but the code is worth studying
-for extension writers.
-
-=back
-
-=head2 Updated And Improved Modules and Pragmata
-
-=over 4
-
-=item *
-
-The following independently supported modules have been updated to the
-newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp,
-Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle
-(Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser, Storable,
-Term::ANSIColor, Test, Text-Tabs+Wrap.
-
-=item *
-
-attributes::reftype() now works on tied arguments.
-
-=item *
-
-AutoLoader can now be disabled with C<no AutoLoader;>.
-
-=item *
-
-B::Deparse has been significantly enhanced by Robin Houston. It can
-now deparse almost all of the standard test suite (so that the tests
-still succeed). There is a make target "test.deparse" for trying this
-out.
-
-=item *
-
-Carp now has better interface documentation, and the @CARP_NOT
-interface has been added to get optional control over where errors
-are reported independently of @ISA, by Ben Tilly.
-
-=item *
-
-Class::Struct can now define the classes in compile time.
-
-=item *
-
-Class::Struct now assigns the array/hash element if the accessor
-is called with an array/hash element as the B<sole> argument.
-
-=item *
-
-The return value of Cwd::fastcwd() is now tainted.
-
-=item *
-
-Data::Dumper now has an option to sort hashes.
-
-=item *
-
-Data::Dumper now has an option to dump code references
-using B::Deparse.
-
-=item *
-
-DB_File now supports newer Berkeley DB versions, among
-other improvements.
-
-=item *
-
-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 *
-
-The English module can now be used without the infamous performance
-hit by saying
-
- use English '-no_match_vars';
-
-(Assuming, of course, that you don't need the troublesome variables
-C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
-C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
-
-=item *
-
-ExtUtils::MakeMaker has been significantly cleaned up and fixed.
-The enhanced version has also been backported to earlier releases
-of Perl and submitted to CPAN so that the earlier releases can
-enjoy the fixes.
-
-=item *
-
-The arguments of WriteMakefile() in Makefile.PL are now checked
-for sanity much more carefully than before. This may cause new
-warnings when modules are being insalled. See L<ExtUtils::MakeMaker>
-for more details.
-
-=item *
-
-ExtUtils::MakeMaker now uses File::Spec internally, which hopefully
-leads to better portability.
-
-=item *
-
-Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clark
-to use the new-style constant dispatch section (see L<ExtUtils::Constant>).
-This means that they will be more robust and hopefully faster.
-
-=item *
-
-File::Find now chdir()s correctly when chasing symbolic links. [561]
-
-=item *
-
-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 *
-
-File::Find is now (again) reentrant. It also has been made
-more portable.
-
-=item *
-
-The warnings issued by File::Find now belong to their own category.
-You can enable/disable them with C<use/no warnings 'File::Find';>.
-
-=item *
-
-File::Glob::glob() has been renamed to File::Glob::bsd_glob()
-because the name clashes with the builtin glob(). The older
-name is still available for compatibility, but is deprecated. [561]
-
-=item *
-
-File::Glob now supports C<GLOB_LIMIT> constant to limit the size of
-the returned list of filenames.
-
-=item *
-
-IPC::Open3 now allows the use of numeric file descriptors.
-
-=item *
-
-IO::Socket now has an atmark() method, which returns true if the socket
-is positioned at the out-of-band mark. The method is also exportable
-as a sockatmark() function.
-
-=item *
-
-IO::Socket::INET failed to open the specified port if the service name
-was not known. It now correctly uses the supplied port number as is. [561]
-
-=item *
-
-IO::Socket::INET has support for the ReusePort option (if your
-platform supports it). The Reuse option now has an alias, ReuseAddr.
-For clarity, you may want to prefer ReuseAddr.
-
-=item *
-
-IO::Socket::INET now supports a value of zero for C<LocalPort>
-(usually meaning that the operating system will make one up.)
-
-=item *
-
-'use lib' now works identically to @INC. Removing directories
-with 'no lib' now works.
-
-=item *
-
-Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels.
-They are now magnitudes faster, and they support various bignum
-libraries such as GMP and PARI as their backends.
-
-=item *
-
-Math::Complex handles inf, NaN etc., better.
-
-=item *
-
-Net::Ping has been considerably enhanced by Rob Brown: multihoming is
-now supported, Win32 functionality is better, there is now time
-measuring functionality (optionally high-resolution using
-Time::HiRes), and there is now "external" protocol which uses
-Net::Ping::External module which runs your external ping utility and
-parses the output. A version of Net::Ping::External is available in
-CPAN.
-
-Note that some of the Net::Ping tests are disabled when running
-under the Perl distribution since one cannot assume one or more
-of the following: enabled echo port at localhost, full Internet
-connectivity, or sympathetic firewalls. You can set the environment
-variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test
-suite to enable all the Net::Ping tests.
-
-=item *
-
-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 *
-
-In Safe, C<%INC> is now localised in a Safe compartment so that
-use/require work.
-
-=item *
-
-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 *
-
-In Sys::Syslog there is now a failover mechanism that will go
-through alternative connection mechanisms until the message
-is successfully logged.
-
-=item *
-
-The Test module has been significantly enhanced.
-
-=item *
-
-Time::Local::timelocal() does not handle fractional seconds anymore.
-The rationale is that neither does localtime(), and timelocal() and
-localtime() are supposed to be inverses of each other.
-
-=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<enc2xs> is a tool for people adding their own encodings to the
-Encode module.
-
-=item *
-
-C<h2ph> now supports C trigraphs.
-
-=item *
-
-C<h2xs> now produces a template README.
-
-=item *
-
-C<h2xs> now uses C<Devel::PPPort> for better portability between
-different versions of Perl.
-
-=item *
-
-C<h2xs> uses the new L<ExtUtils::Constant|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>
-got 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 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.)
-B<Note that perlcc is still considered very experimental and
-unsupported.> [561]
-
-=item *
-
-C<perlivp> is a new Installation Verification Procedure utility
-for running any time after installing Perl.
-
-=item *
-
-C<piconv> is an implementation of the character conversion utility
-C<iconv>, demonstrating the new Encode module.
-
-=item *
-
-C<pod2html> now allows specifying a cache directory.
-
-=item *
-
-C<pod2html> now produces XHTML 1.0.
-
-=item *
-
-C<pod2html> now understands POD written using different line endings
-(PC-like CRLF versus UNIX-like LF versus MacClassic-like CR).
-
-=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. [561]
-
-=item *
-
-C<xsubpp> now supports the 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.) [561+]
-
-=item *
-
-perldebtut is a Perl debugging tutorial. [561+]
-
-=item *
-
-perlebcdic contains considerations for running Perl on EBCDIC
-platforms. [561+]
-
-=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. [561+]
-
-=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. [561+]
-
-=item *
-
-perlrequick is a regular expressions quick-start guide.
-Yes, much quicker than perlretut. [561]
-
-=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. [561+]
-
-=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 perlfreebsd perlhpux
- perlhurd perlirix perlmachten perlmacos perlmint perlmpeix
- perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
- perltru64 perluts perlvmesa perlvms perlvos perlwin32
-
-These documents usually detail one or more of the following subjects:
-configuring, building, testing, installing, and sometimes also using
-Perl on the said platform.
-
-Eastern Asian Perl users are now welcomed in their own languages:
-README.jp (Japanese), README.ko (Korean), README.cn (simplified
-Chinese) and README.tw (traditional Chinese), which are written in
-normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These
-will get installed as
-
- perljp perlko perlcn perltw
-
-=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 perlce (README.ce
-in the source code kit), 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. [561]
-
-=item *
-
-sort() is also fully reentrant, in the sense that the sort function
-can itself call sort(). This did not work reliably in previous
-releases. [561]
-
-=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) <=> ($b % 2) } (3,1,4,1,5,9);
-
-will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers
-appear in the output in the same order they appeared in the input.
-Mergesort has worst case O(N log N) behaviour, the best value
-attainable. And, ironically, this mergesort does particularly
-well where quicksort goes quadratic: mergesort sorts (1..$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 *
-
-Since Perl 5.8 is not binary-compatible with previous releases
-of Perl, Configure no longer suggests including the 5.005
-modules in @INC.
-
-=item *
-
-Configure C<-S> can now run non-interactively. [561]
-
-=item *
-
-Configure support for pdp11-style memory models has been removed due
-to obsolescence. [561]
-
-=item *
-
-configure.gnu now works with options with whitespace in them.
-
-=item *
-
-installperl now outputs everything to STDERR.
-
-=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 lesser-known 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. This file 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.
-[561]
-
-=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.
-
-=item *
-
-The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying
-floating-point numbers is now more picky about using sprintf %.*g
-rules for the conversion. Some platforms that used to use gcvt may
-now resort to the slower sprintf.
-
-=item *
-
-The obsolete method of making a special (e.g., debugging) flavor
-of perl by saying
-
- make LIBPERL=libperld.a
-
-has been removed. Use -DDEBUGGING instead.
-
-=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 *
-
-AtheOS ( http://www.atheos.cx/ ) is a new platform.
-
-=item *
-
-BeOS has been reclaimed.
-
-=item *
-
-The DG/UX platform now supports 5.005-style threads.
-See L<perldgux>.
-
-=item *
-
-The 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. [561]
-
-=item *
-
-Mac OS Classic is now supported in the mainstream source package
-(MacPerl has of course been available since perl 5.004 but now the
-source code bases of standard Perl and MacPerl have been synchronised)
-[561]
-
-=item *
-
-Mac OS X (or Darwin) should now be able to build Perl even on HFS+
-filesystems. (The case-insensitivity used to confuse the Perl build
-process.)
-
-=item *
-
-NCR MP-RAS is now supported. [561]
-
-=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. [561]
-
-=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 thread tests
-of Perl now work, but not without adding some yield()s to the tests,
-so while pth (and other userlevel thread implementations) can be
-considered to be "working" with Perl ithreads, keep in mind the
-possible non-preemptability of the underlying thread implementation.
-
-=item *
-
-Stratus VOS is now supported using Perl's native build method
-(Configure). This is the recommended method to build Perl on
-VOS. The older methods, which build miniperl, are still
-available. See L<perlvos>. [561+]
-
-=item *
-
-The Amdahl UTS UNIX mainframe platform is now supported. [561]
-
-=item *
-
-WinCE is now supported. See L<perlce>.
-
-=item *
-
-z/OS (formerly known as OS/390, formerly known as MVS OE) now has
-support for dynamic loading. This is not selected by default,
-however, you must specify -Dusedl in the arguments of Configure. [561]
-
-=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. [561]
-
-=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. In particular, caller() now
-returns a subroutine name of C<(unknown)> for subroutines that have
-been removed from the symbol table.
-
-=item *
-
-chop(@list) in list context returned the characters chopped in
-reverse order. This has been reversed to be in the right order. [561]
-
-=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. [561]
-
-=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's 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 *
-
-Perl 5.6.0 could emit spurious warnings about redefinition of
-dl_error() when statically building extensions into perl.
-This has been corrected. [561]
-
-=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.) [561]
-
-=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. [561]
-
-=item *
-
-warnings::enabled() now reports the state of $^W correctly if the caller
-isn't using lexical warnings. [561]
-
-=item *
-
-Line renumbering with eval and C<#line> now works. [561]
-
-=item *
-
-Fixed numerous memory leaks, especially in eval "".
-
-=item *
-
-Localised tied variables no longer leak memory
-
- use Tie::Hash;
- tie my %tied_hash => 'Tie::StdHash';
-
- ...
-
- # Used to leak memory every time local() was called;
- # in a loop, this added up.
- local($tied_hash{Foo}) = 1;
-
-=item *
-
-Localised hash elements (and %ENV) are correctly unlocalised to not
-exist, if they didn't before they were localised.
-
-
- use Tie::Hash;
- tie my %tied_hash => 'Tie::StdHash';
-
- ...
-
- # Nothing has set the FOO element so far
-
- { local $tied_hash{FOO} = 'Bar' }
-
- # This used to print, but not now.
- print "exists!\n" if exists $tied_hash{FOO};
-
-As a side effect of this fix, tied hash interfaces B<must> define
-the EXISTS and DELETE methods.
-
-=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). [561]
-
-=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. [561]
-
-=item *
-
-Numeric conversions did not recognize changes in the string value
-properly in certain circumstances. [561]
-
-=item *
-
-Attributes (such as :shared) didn't work with our().
-
-=item *
-
-our() variables will not cause bogus "Variable will not stay shared"
-warnings. [561]
-
-=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. [561]
-
-=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. [561]
-
-=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'>: that is, as three
-characters, not four. [561]
-
-=item *
-
-pos() did not return the correct value within s///ge in earlier
-versions. This is now handled correctly. [561]
-
-=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. [561+]
-
-=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. [561]
-
-=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. [561]
-
-=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. [561]
-
-=item *
-
-Regular expression debug output (whether through C<use re 'debug'>
-or via C<-Dr>) now looks better. [561]
-
-=item *
-
-Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The
-bug has been fixed. [561]
-
-=item *
-
-Use of $& could trigger a core dump under some situations. This
-is now avoided. [561]
-
-=item *
-
-The regular expression captured submatches ($1, $2, ...) are now
-more consistently unset if the match fails, instead of leaving false
-data lying around in them. [561]
-
-=item *
-
-readline() on files opened in "slurp" mode could return an extra
-"" (blank line) at the end in certain situations. This has been
-corrected. [561]
-
-=item *
-
-Autovivification of symbolic references of special variables described
-in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works
-again now. [561]
-
-=item *
-
-Sys::Syslog ignored the C<LOG_AUTH> constant.
-
-=item *
-
-$AUTOLOAD, sort(), lock(), and spawning subprocesses
-in multiple threads simultaneously are now thread-safe.
-
-=item *
-
-Tie::Array's SPLICE method was broken.
-
-=item *
-
-Allow a read-only string on the left-hand side of a non-modifying tr///.
-
-=item *
-
-If C<STDERR> is tied, warnings caused by C<warn> and C<die> now
-correctly pass to it.
-
-=item *
-
-Several Unicode fixes.
-
-=over 8
-
-=item *
-
-BOMs (byte order marks) at the beginning of Perl files
-(scripts, modules) should now be transparently skipped.
-UTF-16 and UCS-2 encoded Perl files should now be read correctly.
-
-=item *
-
-The character tables have been updated to Unicode 3.2.0.
-
-=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 such as 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. [561]
-
-=item *
-
-Zero entries were missing from the Unicode classes such as C<IsDigit>.
-
-=back
-
-=item *
-
-Large unsigned numbers (those above 2**31) could sometimes lose their
-unsignedness, causing bogus results in arithmetic operations. [561]
-
-=item *
-
-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.