perl595delta
(1)
Name
perl595delta - what is new for perl v5.9.5
Synopsis
Please see following description for synopsis
Description
Perl Programmers Reference Guide PERL595DELTA(1)
NAME
perl595delta - what is new for perl v5.9.5
DESCRIPTION
This document describes differences between the 5.9.4 and
the 5.9.5 development releases. See perl590delta,
perl591delta, perl592delta, perl593delta and perl594delta
for the differences between 5.8.0 and 5.9.4.
Incompatible Changes
Tainting and printf
When perl is run under taint mode, "printf()" and
"sprintf()" will now reject any tainted format argument.
(Rafael Garcia-Suarez)
undef and signal handlers
Undefining or deleting a signal handler via "undef
$SIG{FOO}" is now equivalent to setting it to 'DEFAULT'.
(Rafael)
strictures and array/hash dereferencing in defined()
"defined @$foo" and "defined %$bar" are now subject to
"strict 'refs'" (that is, $foo and $bar shall be proper
references there.) (Nicholas Clark)
(However, "defined(@foo)" and "defined(%bar)" are
discouraged constructs anyway.)
"(?p{})" has been removed
The regular expression construct "(?p{})", which was
deprecated in perl 5.8, has been removed. Use "(??{})"
instead. (Rafael)
Pseudo-hashes have been removed
Support for pseudo-hashes has been removed from Perl 5.9.
(The "fields" pragma remains here, but uses an alternate
implementation.)
Removal of the bytecode compiler and of perlcc
"perlcc", the byteloader and the supporting modules (B::C,
B::CC, B::Bytecode, etc.) are no longer distributed with the
perl sources. Those experimental tools have never worked
reliably, and, due to the lack of volunteers to keep them in
line with the perl interpreter developments, it was decided
to remove them instead of shipping a broken version of
those. The last version of those modules can be found with
perl 5.9.4.
However the B compiler framework stays supported in the perl
core, as with the more useful modules it has permitted
(among others, B::Deparse and B::Concise).
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Removal of the JPL
The JPL (Java-Perl Linguo) has been removed from the perl
sources tarball.
Recursive inheritance detected earlier
Perl will now immediately throw an exception if you modify
any package's @ISA in such a way that it would cause
recursive inheritance.
Previously, the exception would not occur until Perl
attempted to make use of the recursive inheritance while
resolving a method or doing a "$foo->isa($bar)" lookup.
Core Enhancements
Regular expressions
Recursive Patterns
It is now possible to write recursive patterns without
using the "(??{})" construct. This new way is more
efficient, and in many cases easier to read.
Each capturing parenthesis can now be treated as an
independent pattern that can be entered by using the
"(?PARNO)" syntax ("PARNO" standing for "parenthesis
number"). For example, the following pattern will match
nested balanced angle brackets:
/
^ # start of line
( # start capture buffer 1
< # match an opening angle bracket
(?: # match one of:
(?> # don't backtrack over the inside of this group
[^<>]+ # one or more non angle brackets
) # end non backtracking group
| # ... or ...
(?1) # recurse to bracket 1 and try it again
)* # 0 or more times.
> # match a closing angle bracket
) # end capture buffer one
$ # end of line
/x
Note, users experienced with PCRE will find that the
Perl implementation of this feature differs from the
PCRE one in that it is possible to backtrack into a
recursed pattern, whereas in PCRE the recursion is
atomic or "possessive" in nature. (Yves Orton)
Named Capture Buffers
It is now possible to name capturing parenthesis in a
pattern and refer to the captured contents by name. The
naming syntax is "(?<NAME>....)". It's possible to
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backreference to a named buffer with the "\k<NAME>"
syntax. In code, the new magical hashes "%+" and "%-"
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 it's possible to do something like
foreach my $name (keys %+) {
print "content of buffer '$name' is $+{$name}\n";
}
The "%-" 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.
"%+" and "%-" are implemented as tied hashes through the
new module "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
/(A)(?<B>B)(C)(?<D>D)/
$1 will be 'A', $2 will be 'B', $3 will be 'C' and $4
will be 'D' and not $1 is 'A', $2 is 'C' and $3 is 'B'
and $4 is 'D' that a .NET programmer would expect. This
is considered a feature. :-) (Yves Orton)
Possessive Quantifiers
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 similar to non-greedy matching, except instead
of using a '?' as the modifier the '+' is used. Thus
"?+", "*+", "++", "{min,max}+" are now legal
quantifiers. (Yves Orton)
Backtracking control verbs
The regex engine now supports a number of special-
purpose backtrack control verbs: (*THEN), (*PRUNE),
(*MARK), (*SKIP), (*COMMIT), (*FAIL) and (*ACCEPT). See
perlre for their descriptions. (Yves Orton)
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Relative backreferences
A new syntax "\g{N}" or "\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 "Capture buffers" in perlre.
(Yves Orton)
"\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 "\K" as a way to do
something like floating length positive lookbehind. It
is also useful in substitutions like:
s/(foo)bar/$1/g
that can now be converted to
s/foo\Kbar//g
which is much more efficient. (Yves Orton)
Vertical and horizontal whitespace, and linebreak
Regular expressions now recognize the "\v" and "\h"
escapes, that match vertical and horizontal whitespace,
respectively. "\V" and "\H" logically match their
complements.
"\R" matches a generic linebreak, that is, vertical
whitespace, plus the multi-character sequence
"\x0D\x0A".
The "_" prototype
A new prototype character has been added. "_" is equivalent
to "$" (it denotes a scalar), but defaults to $_ if the
corresponding argument isn't supplied. Due to the optional
nature of the argument, you can only use it at the end of a
prototype, or before a semicolon.
This has a small incompatible consequence: the prototype()
function has been adjusted to return "_" for some built-ins
in appropriate cases (for example,
"prototype('CORE::rmdir')"). (Rafael)
UNITCHECK blocks
"UNITCHECK", a new special code block has been introduced,
in addition to "BEGIN", "CHECK", "INIT" and "END".
"CHECK" and "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
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are useless whenever code is loaded at runtime. On the other
hand, "UNITCHECK" blocks are executed just after the unit
which defined them has been compiled. See perlmod for more
information. (Alex Gough)
readpipe() is now overridable
The built-in function readpipe() is now overridable.
Overriding it permits also to override its operator
counterpart, "qx//" (a.k.a. "``"). Moreover, it now
defaults to $_ if no argument is provided. (Rafael)
default argument for readline()
readline() now defaults to *ARGV if no argument is provided.
(Rafael)
UCD 5.0.0
The copy of the Unicode Character Database included in Perl
5.9 has been updated to version 5.0.0.
Smart match
The smart match operator ("~~") is now available by default
(you don't need to enable it with "use feature" any longer).
(Michael G Schwern)
Implicit loading of "feature"
The "feature" pragma is now implicitly loaded when you
require a minimal perl version (with the "use VERSION"
construct) greater than, or equal to, 5.9.5.
Modules and Pragmas
New Pragma, "mro"
A new pragma, "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 mro for more information.
(Brandon Black)
Note that, due to changes in the implementation of class
hierarchy search, code that used to undef the *ISA glob will
most probably break. Anyway, undef'ing *ISA had the side-
effect of removing the magic on the @ISA array and should
not have been done in the first place.
bignum, bigint, bigrat
The three numeric pragmas "bignum", "bigint" and "bigrat"
are now lexically scoped. (Tels)
Math::BigInt/Math::BigFloat
Many bugs have been fixed; noteworthy are comparisons with
NaN, which no longer warn about undef values.
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The following things are new:
config()
The config() method now also supports the calling-style
"config('lib')" in addition to "config()->{'lib'}".
import()
Upon import, using "lib => 'Foo'" now warns if the low-
level library cannot be found. To suppress the warning,
you can use "try => 'Foo'" instead. To convert the
warning into a die, use "only => 'Foo'" instead.
roundmode common
A rounding mode of "common" is now supported.
Also, support for the following methods has been added:
bpi(), bcos(), bsin(), batan(), batan2()
bmuladd()
bexp(), bnok()
from_hex(), from_oct(), and from_bin()
as_oct()
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.
New Core Modules
o "Locale::Maketext::Simple", needed by CPANPLUS, is a
simple wrapper around "Locale::Maketext::Lexicon". Note
that "Locale::Maketext::Lexicon" isn't included in the
perl core; the behaviour of "Locale::Maketext::Simple"
gracefully degrades when the later isn't present.
o "Params::Check" implements a generic input
parsing/checking mechanism. It is used by CPANPLUS.
o "Term::UI" simplifies the task to ask questions at a
terminal prompt.
o "Object::Accessor" provides an interface to create per-
object accessors.
o "Module::Pluggable" is a simple framework to create
modules that accept pluggable sub-modules.
o "Module::Load::Conditional" provides simple ways to
query and possibly load installed modules.
o "Time::Piece" provides an object oriented interface to
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time functions, overriding the built-ins localtime() and
gmtime().
o "IPC::Cmd" helps to find and run external commands,
possibly interactively.
o "File::Fetch" provide a simple generic file fetching
mechanism.
o "Log::Message" and "Log::Message::Simple" are used by
the log facility of "CPANPLUS".
o "Archive::Extract" is a generic archive extraction
mechanism for .tar (plain, gziped or bzipped) or .zip
files.
o "CPANPLUS" provides an API and a command-line tool to
access the CPAN mirrors.
Module changes
"assertions"
The "assertions" pragma, its submodules
"assertions::activate" and "assertions::compat" and the
-A command-line switch have been removed. The interface
was not judged mature enough for inclusion in a stable
release.
"base"
The "base" pragma now warns if a class tries to inherit
from itself. (Curtis "Ovid" Poe)
"strict" and "warnings"
"strict" and "warnings" will now complain loudly if they
are loaded via incorrect casing (as in "use Strict;").
(Johan Vromans)
"warnings"
The "warnings" pragma doesn't load "Carp" anymore. That
means that code that used "Carp" routines without having
loaded it at compile time might need to be adjusted;
typically, the following (faulty) code won't work
anymore, and will require parentheses to be added after
the function name:
use warnings;
require Carp;
Carp::confess "argh";
"less"
"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
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have requested to use less CPU, or less memory, less
magic, or maybe even less fat. See less for more.
(Joshua ben Jore)
"Attribute::Handlers"
"Attribute::Handlers" can now report the caller's file
and line number. (David Feldman)
"B::Lint"
"B::Lint" is now based on "Module::Pluggable", and so
can be extended with plugins. (Joshua ben Jore)
"B" It's now possible to access the lexical pragma hints
("%^H") by using the method B::COP::hints_hash(). It
returns a "B::RHE" object, which in turn can be used to
get a hash reference via the method B::RHE::HASH().
(Joshua ben Jore)
"Thread"
As the old 5005thread threading model has been removed,
in favor of the ithreads scheme, the "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.
Utility Changes
"cpanp"
"cpanp", the CPANPLUS shell, has been added.
("cpanp-run-perl", an helper for CPANPLUS operation, has
been added too, but isn't intended for direct use).
"cpan2dist"
"cpan2dist" is a new utility, that comes with CPANPLUS. It's
a tool to create distributions (or packages) from CPAN
modules.
"pod2html"
The output of "pod2html" has been enhanced to be more
customizable via CSS. Some formatting problems were also
corrected. (Jari Aalto)
Documentation
New manpage, perlunifaq
A new manual page, perlunifaq (the Perl Unicode FAQ), has
been added (Juerd Waalboer).
Installation and Configuration Improvements
C++ compatibility
Efforts have been made to make perl and the core XS modules
compilable with various C++ compilers (although the
situation is not perfect with some of the compilers on some
of the platforms tested.)
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Visual C++
Perl now can be compiled with Microsoft Visual C++ 2005.
Static build on Win32
It's now possible to build a "perl-static.exe" that doesn't
depend on "perl59.dll" on Win32. See the Win32 makefiles for
details. (Vadim Konovalov)
win32 builds
All win32 builds (MS-Win, WinCE) have been merged and
cleaned up.
"d_pseudofork" and "d_printf_format_null"
A new configuration variable, available as
$Config{d_pseudofork} in the Config module, has been added,
to distinguish real fork() support from fake pseudofork used
on Windows platforms.
A new configuration variable, "d_printf_format_null", has
been added, to see if printf-like formats are allowed to be
NULL.
Help
"Configure -h" has been extended with the most used option.
Much less 'Whoa there' messages.
64bit systems
Better detection of 64bit(only) systems, and setting all the
(library) paths accordingly.
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.
Selected Bug Fixes
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 "Deferred Signals (Safe
Signals)" in perlipc). (Rafael)
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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 "-w" and "-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 ":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 "local $h{$x}; ++$x"). (Bo
Lindbergh)
New or Changed Diagnostics
Deprecations
Two deprecation warnings have been added: (Rafael)
Opening dirhandle %s also as a file
Opening filehandle %s also as a directory
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).
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://rt.perl.org/rt3/ . There may also be information at
http://www.perl.org/ , the Perl Home Page.
If you believe you have an unreported bug, please run the
perlbug program included with your release. Be sure to trim
your bug down to a tiny but sufficient test case. Your bug
report, along with the output of "perl -V", will be sent off
to perlbug@perl.org to be analysed by the Perl porting team.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
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+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | runtime/perl-512 |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.cpan.org/src/5.0/perl-5.12.5.tar.bz2
Further information about this software can be found on the
open source community website at http://www.perl.org/.
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