=head1 NAME
-perldelta - what is new for perl v5.9.5
+perl595delta - what is new for perl v5.9.5
=head1 DESCRIPTION
=head1 Incompatible Changes
+=head2 Tainting and printf
+
+When perl is run under taint mode, C<printf()> and C<sprintf()> will now
+reject any tainted format argument. (Rafael Garcia-Suarez)
+
+=head2 undef and signal handlers
+
+Undefining or deleting a signal handler via C<undef $SIG{FOO}> is now
+equivalent to setting it to C<'DEFAULT'>. (Rafael)
+
+=head2 strictures and array/hash dereferencing in defined()
+
+C<defined @$foo> and C<defined %$bar> are now subject to C<strict 'refs'>
+(that is, C<$foo> and C<$bar> shall be proper references there.)
+(Nicholas Clark)
+
+(However, C<defined(@foo)> and C<defined(%bar)> are discouraged constructs
+anyway.)
+
+=head2 C<(?p{})> has been removed
+
+The regular expression construct C<(?p{})>, which was deprecated in perl
+5.8, has been removed. Use C<(??{})> instead. (Rafael)
+
+=head2 Pseudo-hashes have been removed
+
+Support for pseudo-hashes has been removed from Perl 5.9. (The C<fields>
+pragma remains here, but uses an alternate implementation.)
+
=head2 Removal of the bytecode compiler and of perlcc
C<perlcc>, the byteloader and the supporting modules (B::C, B::CC,
The JPL (Java-Perl Linguo) has been removed from the perl sources tarball.
+=head2 Recursive inheritance detected earlier
+
+Perl will now immediately throw an exception if you modify any package's
+C<@ISA> in such a way that it would cause recursive inheritance.
+
+Previously, the exception would not occur until Perl attempted to make
+use of the recursive inheritance while resolving a method or doing a
+C<$foo-E<gt>isa($bar)> lookup.
+
=head1 Core Enhancements
=head2 Regular expressions
It is now possible to name capturing parenthesis in a pattern and refer to
the captured contents by name. The naming syntax is C<< (?<NAME>....) >>.
It's possible to backreference to a named buffer with the C<< \k<NAME> >>
-syntax. In code, the new magical hash C<%+> can be used to access the
-contents of the buffers.
+syntax. In code, the new magical hashes C<%+> and C<%-> can be used to
+access the contents of the capture buffers.
Thus, to replace all doubled chars, one could write
s/(?<letter>.)\k<letter>/$+{letter}/g
-Only buffers with defined contents will be "visible" in the hash, so
+Only buffers with defined contents will be "visible" in the C<%+> hash, so
it's possible to do something like
foreach my $name (keys %+) {
print "content of buffer '$name' is $+{$name}\n";
}
+The C<%-> hash is a bit more complete, since it will contain array refs
+holding values from all capture buffers similarly named, if there should
+be many of them.
+
+C<%+> and C<%-> are implemented as tied hashes through the new module
+C<Tie::Hash::NamedCapture>.
+
Users exposed to the .NET regex engine will find that the perl
implementation differs in that the numerical ordering of the buffers
is sequential, and not "unnamed first, then named". Thus in the pattern
=item Possessive Quantifiers
-Perl now supports the "possessive quantifier" syntax of the "atomic match"
+Perl now supports the "possessive quantifier" syntax of the "atomic match"
pattern. Basically a possessive quantifier matches as much as it can and never
-gives any back. Thus it can be used to control backtracking. The syntax is
+gives any back. Thus it can be used to control backtracking. The syntax is
similar to non-greedy matching, except instead of using a '?' as the modifier
the '+' is used. Thus C<?+>, C<*+>, C<++>, C<{min,max}+> are now legal
quantifiers. (Yves Orton)
=item Backtracking control verbs
-The regex engine now supports a number of special purpose backtrack
-control verbs: (*COMMIT), (*MARK), (*CUT), (*ERROR), (*FAIL) and
-(*ACCEPT). See L<perlre> for their descriptions.
+The regex engine now supports a number of special-purpose backtrack
+control verbs: (*THEN), (*PRUNE), (*MARK), (*SKIP), (*COMMIT), (*FAIL)
+and (*ACCEPT). See L<perlre> for their descriptions. (Yves Orton)
+
+=item Relative backreferences
+
+A new syntax C<\g{N}> or C<\gN> where "N" is a decimal integer allows a
+safer form of back-reference notation as well as allowing relative
+backreferences. This should make it easier to generate and embed patterns
+that contain backreferences. See L<perlre/"Capture buffers">. (Yves Orton)
+
+=item C<\K> escape
+
+The functionality of Jeff Pinyan's module Regexp::Keep has been added to
+the core. You can now use in regular expressions the special escape C<\K>
+as a way to do something like floating length positive lookbehind. It is
+also useful in substitutions like:
+
+ s/(foo)bar/$1/g
+
+that can now be converted to
+
+ s/foo\Kbar//g
+
+which is much more efficient. (Yves Orton)
+
+=item Vertical and horizontal whitespace, and linebreak
+
+Regular expressions now recognize the C<\v> and C<\h> escapes, that match
+vertical and horizontal whitespace, respectively. C<\V> and C<\H>
+logically match their complements.
+
+C<\R> matches a generic linebreak, that is, vertical whitespace, plus
+the multi-character sequence C<"\x0D\x0A">.
=back
This has a small incompatible consequence: the prototype() function has
been adjusted to return C<_> for some built-ins in appropriate cases (for
-example, C<prototype('CORE::rmdir')>). (Rafael Garcia-Suarez)
+example, C<prototype('CORE::rmdir')>). (Rafael)
+
+=head2 UNITCHECK blocks
+
+C<UNITCHECK>, a new special code block has been introduced, in addition to
+C<BEGIN>, C<CHECK>, C<INIT> and C<END>.
+
+C<CHECK> and C<INIT> blocks, while useful for some specialized purposes,
+are always executed at the transition between the compilation and the
+execution of the main program, and thus are useless whenever code is
+loaded at runtime. On the other hand, C<UNITCHECK> blocks are executed
+just after the unit which defined them has been compiled. See L<perlmod>
+for more information. (Alex Gough)
+
+=head2 readpipe() is now overridable
+
+The built-in function readpipe() is now overridable. Overriding it permits
+also to override its operator counterpart, C<qx//> (a.k.a. C<``>).
+Moreover, it now defaults to C<$_> if no argument is provided. (Rafael)
+
+=head2 default argument for readline()
+
+readline() now defaults to C<*ARGV> if no argument is provided. (Rafael)
=head2 UCD 5.0.0
The copy of the Unicode Character Database included in Perl 5.9 has
been updated to version 5.0.0.
+=head2 Smart match
+
+The smart match operator (C<~~>) is now available by default (you don't
+need to enable it with C<use feature> any longer). (Michael G Schwern)
+
+=head2 Implicit loading of C<feature>
+
+The C<feature> pragma is now implicitly loaded when you require a minimal
+perl version (with the C<use VERSION> construct) greater than, or equal
+to, 5.9.5.
+
=head1 Modules and Pragmas
+=head2 New Pragma, C<mro>
+
+A new pragma, C<mro> (for Method Resolution Order) has been added. It
+permits to switch, on a per-class basis, the algorithm that perl uses to
+find inherited methods in case of a multiple inheritance hierarchy. The
+default MRO hasn't changed (DFS, for Depth First Search). Another MRO is
+available: the C3 algorithm. See L<mro> for more information.
+(Brandon Black)
+
+Note that, due to changes in the implementation of class hierarchy search,
+code that used to undef the C<*ISA> glob will most probably break. Anyway,
+undef'ing C<*ISA> had the side-effect of removing the magic on the @ISA
+array and should not have been done in the first place.
+
+=head2 bignum, bigint, bigrat
+
+The three numeric pragmas C<bignum>, C<bigint> and C<bigrat> are now
+lexically scoped. (Tels)
+
+=head2 Math::BigInt/Math::BigFloat
+
+Many bugs have been fixed; noteworthy are comparisons with NaN, which
+no longer warn about undef values.
+
+The following things are new:
+
+=over 4
+
+=item config()
+
+The config() method now also supports the calling-style
+C<< config('lib') >> in addition to C<< config()->{'lib'} >>.
+
+=item import()
+
+Upon import, using C<< lib => 'Foo' >> now warns if the low-level library
+cannot be found. To suppress the warning, you can use C<< try => 'Foo' >>
+instead. To convert the warning into a die, use C<< only => 'Foo' >>
+instead.
+
+=item roundmode common
+
+A rounding mode of C<common> is now supported.
+
+=back
+
+Also, support for the following methods has been added:
+
+=over 4
+
+=item bpi(), bcos(), bsin(), batan(), batan2()
+
+=item bmuladd()
+
+=item bexp(), bnok()
+
+=item from_hex(), from_oct(), and from_bin()
+
+=item as_oct()
+
+=back
+
+In addition, the default math-backend (Calc (Perl) and FastCalc (XS)) now
+support storing numbers in parts with 9 digits instead of 7 on Perls with
+either 64bit integer or long double support. This means math operations
+scale better and are thus faster for really big numbers.
+
=head2 New Core Modules
=over 4
C<Params::Check> implements a generic input parsing/checking mechanism. It
is used by CPANPLUS.
+=item *
+
+C<Term::UI> simplifies the task to ask questions at a terminal prompt.
+
+=item *
+
+C<Object::Accessor> provides an interface to create per-object accessors.
+
+=item *
+
+C<Module::Pluggable> is a simple framework to create modules that accept
+pluggable sub-modules.
+
+=item *
+
+C<Module::Load::Conditional> provides simple ways to query and possibly
+load installed modules.
+
+=item *
+
+C<Time::Piece> provides an object oriented interface to time functions,
+overriding the built-ins localtime() and gmtime().
+
+=item *
+
+C<IPC::Cmd> helps to find and run external commands, possibly
+interactively.
+
+=item *
+
+C<File::Fetch> provide a simple generic file fetching mechanism.
+
+=item *
+
+C<Log::Message> and C<Log::Message::Simple> are used by the log facility
+of C<CPANPLUS>.
+
+=item *
+
+C<Archive::Extract> is a generic archive extraction mechanism
+for F<.tar> (plain, gziped or bzipped) or F<.zip> files.
+
+=item *
+
+C<CPANPLUS> provides an API and a command-line tool to access the CPAN
+mirrors.
+
=back
=head2 Module changes
=over 4
+=item C<assertions>
+
+The C<assertions> pragma, its submodules C<assertions::activate> and
+C<assertions::compat> and the B<-A> command-line switch have been removed.
+The interface was not judged mature enough for inclusion in a stable
+release.
+
=item C<base>
The C<base> pragma now warns if a class tries to inherit from itself.
+(Curtis "Ovid" Poe)
+
+=item C<strict> and C<warnings>
+
+C<strict> and C<warnings> will now complain loudly if they are loaded via
+incorrect casing (as in C<use Strict;>). (Johan Vromans)
=item C<warnings>
require Carp;
Carp::confess "argh";
+=item C<less>
+
+C<less> now does something useful (or at least it tries to). In fact, it
+has been turned into a lexical pragma. So, in your modules, you can now
+test whether your users have requested to use less CPU, or less memory,
+less magic, or maybe even less fat. See L<less> for more. (Joshua ben
+Jore)
+
+=item C<Attribute::Handlers>
+
+C<Attribute::Handlers> can now report the caller's file and line number.
+(David Feldman)
+
+=item C<B::Lint>
+
+C<B::Lint> is now based on C<Module::Pluggable>, and so can be extended
+with plugins. (Joshua ben Jore)
+
+=item C<B>
+
+It's now possible to access the lexical pragma hints (C<%^H>) by using the
+method B::COP::hints_hash(). It returns a C<B::RHE> object, which in turn
+can be used to get a hash reference via the method B::RHE::HASH(). (Joshua
+ben Jore)
+
+=for p5p XXX document this in B.pm too
+
+=item C<Thread>
+
+As the old 5005thread threading model has been removed, in favor of the
+ithreads scheme, the C<Thread> module is now a compatibility wrapper, to
+be used in old code only. It has been removed from the default list of
+dynamic extensions.
+
=back
=head1 Utility Changes
+=head2 C<cpanp>
+
+C<cpanp>, the CPANPLUS shell, has been added. (C<cpanp-run-perl>, an
+helper for CPANPLUS operation, has been added too, but isn't intended for
+direct use).
+
+=head2 C<cpan2dist>
+
+C<cpan2dist> is a new utility, that comes with CPANPLUS. It's a tool to
+create distributions (or packages) from CPAN modules.
+
+=head2 C<pod2html>
+
+The output of C<pod2html> has been enhanced to be more customizable via
+CSS. Some formatting problems were also corrected. (Jari Aalto)
+
=head1 Documentation
-=head1 Performance Enhancements
+=head2 New manpage, perlunifaq
+
+A new manual page, L<perlunifaq> (the Perl Unicode FAQ), has been added
+(Juerd Waalboer).
=head1 Installation and Configuration Improvements
with various C++ compilers (although the situation is not perfect with
some of the compilers on some of the platforms tested.)
+=head2 Visual C++
+
+Perl now can be compiled with Microsoft Visual C++ 2005.
+
+=head2 Static build on Win32
+
+It's now possible to build a C<perl-static.exe> that doesn't depend
+on C<perl59.dll> on Win32. See the Win32 makefiles for details.
+(Vadim Konovalov)
+
+=head2 win32 builds
+
+All win32 builds (MS-Win, WinCE) have been merged and cleaned up.
+
+=head2 C<d_pseudofork> and C<d_printf_format_null>
+
+A new configuration variable, available as C<$Config{d_pseudofork}> in
+the L<Config> module, has been added, to distinguish real fork() support
+from fake pseudofork used on Windows platforms.
+
+A new configuration variable, C<d_printf_format_null>, has been added,
+to see if printf-like formats are allowed to be NULL.
+
+=head2 Help
+
+C<Configure -h> has been extended with the most used option.
+
+Much less 'Whoa there' messages.
+
+=head2 64bit systems
+
+Better detection of 64bit(only) systems, and setting all the (library)
+paths accordingly.
+
=head2 Ports
Perl has been reported to work on MidnightBSD.
+Support for Cray XT4 Catamount/Qk has been added.
+
+Vendor patches have been merged for RedHat and GenToo.
+
=head1 Selected Bug Fixes
-PerlIO::scalar will now prevent writing to read-only scalars.
+PerlIO::scalar will now prevent writing to read-only scalars. Moreover,
+seek() is now supported with PerlIO::scalar-based filehandles, the
+underlying string being zero-filled as needed. (Rafael, Jarkko Hietaniemi)
study() never worked for UTF-8 strings, but could lead to false results.
It's now a no-op on UTF-8 data. (Yves Orton)
+The signals SIGILL, SIGBUS and SIGSEGV are now always delivered in an
+"unsafe" manner (contrary to other signals, that are deferred until the
+perl interpreter reaches a reasonably stable state; see
+L<perlipc/"Deferred Signals (Safe Signals)">). (Rafael)
+
+When a module or a file is loaded through an @INC-hook, and when this hook
+has set a filename entry in %INC, __FILE__ is now set for this module
+accordingly to the contents of that %INC entry. (Rafael)
+
+The C<-w> and C<-t> switches can now be used together without messing
+up what categories of warnings are activated or not. (Rafael)
+
+Duping a filehandle which has the C<:utf8> PerlIO layer set will now
+properly carry that layer on the duped filehandle. (Rafael)
+
+Localizing an hash element whose key was given as a variable didn't work
+correctly if the variable was changed while the local() was in effect (as
+in C<local $h{$x}; ++$x>). (Bo Lindbergh)
+
=head1 New or Changed Diagnostics
+=head2 Deprecations
+
+Two deprecation warnings have been added: (Rafael)
+
+ Opening dirhandle %s also as a file
+ Opening filehandle %s also as a directory
+
=head1 Changed Internals
The anonymous hash and array constructors now take 1 op in the optree
instead of 3, now that pp_anonhash and pp_anonlist return a reference to
an hash/array when the op is flagged with OPf_SPECIAL (Nicholas Clark).
-=head1 Known Problems
+=for p5p XXX have we some docs on how to create regexp engine plugins, since that's now possible ? (perlreguts)
-=head2 Platform Specific Problems
+=for p5p XXX new BIND SV type, #29544, #29642
=head1 Reporting Bugs
https://perl5.git.perl.org / perl5.git / blobdiff