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PERL5215DELTA(1pm)     Perl Programmers Reference Guide     PERL5215DELTA(1pm)




NAME

       perl5215delta - what is new for perl v5.21.5


DESCRIPTION

       This document describes differences between the 5.21.4 release and the
       5.21.5 release.

       If you are upgrading from an earlier release such as 5.21.3, first read
       perl5214delta, which describes differences between 5.21.3 and 5.21.4.


Core Enhancements

   New double-diamond operator
       "<<>>" is like "<>" but uses three-argument "open" to open each file in
       @ARGV.  So each element of @ARGV is an actual file name, and "|foo"
       won't be treated as a pipe open.

   Aliasing via reference
       Variables and subroutines can now be aliased by assigning to a
       reference:

           \$c = \$d;
           \&x = \&y;

       Or by using a backslash before a "foreach" iterator variable, which is
       perhaps the most useful idiom this feature provides:

           foreach \%hash (@array_of_hash_refs) { ... }

       This feature is experimental and must be enabled via "use feature
       'refaliasing'".  It will warn unless the "experimental::refaliasing"
       warnings category is disabled.

       See "Assigning to References" in perlref

   Perl now supports POSIX 2008 locale currency additions.
       On platforms that are able to handle POSIX.1-2008, the hash returned by
       "POSIX::localeconv()" includes the international currency fields added
       by that version of the POSIX standard.  These are "int_n_cs_precedes",
       "int_n_sep_by_space", "int_n_sign_posn", "int_p_cs_precedes",
       "int_p_sep_by_space", and "int_p_sign_posn".

   Packing infinity or not-a-number into a character is now fatal
       Before, when trying to pack infinity or not-a-number into a (signed)
       character, Perl would warn, and assumed you tried to pack 0xFF; if you
       gave it as an argument to "chr", "U+FFFD" was returned.

       But now, all such actions ("pack", "chr", and "print '%c'") result in a
       fatal error.

   Inf and NaN
       Many small improvements, bug fixes and added test cases for dealing
       with math related to infinity and not-a-number.


Security

   Perl is now compiled with -fstack-protector-strong if available
       Perl has been compiled with the anti-stack-smashing option
       "-fstack-protector" since 5.10.1.  Now Perl uses the newer variant
       called "-fstack-protector-strong", if available.  (This was added
       already in 5.21.4.)


Deprecations

   Use of multiple /x regexp modifiers
       It is now deprecated to say something like any of the following:

           qr/foo/xx;
           /(?xax:foo)/;
           use re qw(/amxx);

       That is, now "x" should only occur once in any string of contiguous
       regular expression pattern modifiers.  We do not believe there are any
       occurrences of this in all of CPAN.  This is in preparation for a
       future Perl release having "/xx" mean to allow white-space for
       readability in bracketed character classes (those enclosed in square
       brackets: "[...]").


Performance Enhancements

       o   "length" is up to 20% faster for non-magical/non-tied scalars
           containing a string if it is a non-utf8 string or if "use bytes;"
           is in scope.

       o   Non-magical/non-tied scalars that contain only a floating point
           value and are on most Perl builds with 64 bit integers now use 8-32
           less bytes of memory depending on OS.

       o   In "@array = split", the assignment can be optimized away with
           "split" writing directly to the array.  This optimisation was
           happening only for package arrays other than @_ and only sometimes.
           Now this optimisation happens almost all the time.

       o   "join" is now subject to constant folding.  Moreover, "join" with a
           scalar or constant for the separator and a single-item list to join
           is simplified to a stringification.  The separator doesn't even get
           evaluated.

       o   "qq(@array)" is implemented using two ops: a stringify op and a
           join op.  If the qq contains nothing but a single array, the
           stringification is optimized away.

       o   "our $var" and "our($s,@a,%h)" in void context are no longer
           evaluated at run time.  Even a whole sequence of "our $foo;"
           statements will simply be skipped over.  The same applies to
           "state" variables.


Modules and Pragmata

   Updated Modules and Pragmata
       o   attributes has been upgraded from version 0.23 to 0.24.

           Avoid reading beyond the end of a buffer. [perl #122629]

       o   B has been upgraded from version 1.51 to 1.52.

       o   B::Concise has been upgraded from version 0.993 to 0.994.

           Null ops that are part of the execution chain are now given
           sequence numbers.

           Private flags for nulled ops are now dumped with mnemonics as they
           would be for the non-nulled counterparts.

           B::Deparse has been upgraded from version 1.28 to 1.29.

           Parenthesised arrays in lists passed to "\" are now correctly
           deparsed with parentheses (e.g., "\(@a, (@b), @c)" now retains the
           parentheses around @b), this preserving the flattening behaviour of
           referenced parenthesised arrays.  Formerly, it only worked for one
           array: "\(@a)".

           "local our" is now deparsed correctly, with the "our" included.

           "for($foo; !$bar; $baz) {...}" was deparsed without the "!" (or
           "not").  This has been fixed.

           Core keywords that conflict with lexical subroutines are now
           deparsed with the "CORE::" prefix.

           "foreach state $x (...) {...}" now deparses correctly with "state"
           and not "my".

           "our @array = split(...)" now deparses correctly with "our" in
           those cases where the assignment is optimized away.

       o   B::Debug has been upgraded from version 1.21 to 1.22.

       o   B::Deparse has been upgraded from version 1.28 to 1.29.

       o   Compress::Raw::Bzip2 has been upgraded from version 2.064 to 2.066.

       o   Compress::Raw::Zlib has been upgraded from version 2.065 to 2.066.

       o   CPAN::Meta has been upgraded from version 2.142060 to 2.142690.

       o   DynaLoader has been upgraded from version 1.26 to 1.27.

           Remove dl_nonlazy global if unused in Dynaloader. [perl #122926]

       o   Errno has been upgraded from version 1.20_04 to 1.21.

       o   experimental has been upgraded from version 0.010 to 0.012.

       o   ExtUtils::CBuilder has been upgraded from version 0.280219 to
           0.280220.

       o   ExtUtils::Miniperl has been upgraded from version 1.02 to 1.03.

       o   Fcntl has been upgraded from version 1.11 to 1.13.

           Add support for the Linux pipe buffer size fcntl() commands.

       o   feature has been upgraded from version 1.37 to 1.38.

       o   File::Find has been upgraded from version 1.28 to 1.29.

           Slightly faster module loading time.

       o   File::Spec has been upgraded from version 3.50 to 3.51.

       o   HTTP::Tiny has been upgraded from version 0.049 to 0.050.

       o   The IO-Compress set of modules has been upgraded from version 2.064
           to 2.066.

       o   JSON::PP has been upgraded from version 2.27203 to 2.27300.

       o   The libnet collection of modules has been upgraded from version
           1.27 to 3.02.

           Support for IPv6 and SSL to Net::FTP, Net::NNTP, Net::POP3 and
           Net::SMTP.

           Improvements in Net::SMTP authentication.

       o   Module::CoreList has been upgraded from version 5.20140920 to
           5.20141020.

           Updated to cover the latest releases of Perl.

       o   Opcode has been upgraded from version 1.28 to 1.29.

       o   The PathTools module collection has been upgraded from version 3.50
           to 3.51.

           Slightly faster module loading time.

       o   perlfaq has been upgraded from version 5.0150045 to version
           5.0150046.  [perl #123008]

       o   POSIX has been upgraded from version 1.43 to 1.45.

           POSIX::tmpnam() now produces a deprecation warning.  [perl #122005]

       o   re has been upgraded from version 0.26 to 0.27.

       o   Socket has been upgraded from version 2.015 to 2.016.

       o   Test::Simple has been upgraded from version 1.001006 to 1.001008.

       o   threads::shared has been upgraded from version 1.46 to 1.47.

       o   warnings has been upgraded from version 1.26 to 1.28.

       o   XSLoader has been upgraded from version 0.17 to 0.18.

           Allow XSLoader to load modules from a different namespace.  [perl
           #122455]


Documentation

   Changes to Existing Documentation
       perlrecharclass

       o   Clarifications have been added to "Character Ranges" in
           perlrecharclass to the effect that Perl guarantees that "[A-Z]",
           "[a-z]", "[0-9]" and any subranges thereof in regular expression
           bracketed character classes are guaranteed to match exactly what a
           naive English speaker would expect them to match, even on platforms
           (such as EBCDIC) where special handling is required to accomplish
           this.


Diagnostics

       The following additions or changes have been made to diagnostic output,
       including warnings and fatal error messages.  For the complete list of
       diagnostic messages, see perldiag.

   New Diagnostics
       New Errors

       o   Cannot chr %f

       o   Cannot compress %f in pack

       o   Cannot pack %f with '%c'

       o   Cannot print %f with '%c'

   Changes to Existing Diagnostics
       o   '"my" variable &foo::bar can't be in a package' has been reworded
           to say 'subroutine' instead of 'variable'.


Testing

       o   Some regular expression tests are written in such a way that they
           will run very slowly if certain optimizations break. These tests
           have been moved into new files, t/re/speed.t and t/re/speed_thr.t,
           and are run with a "watchdog()".


Platform Support

   Regained Platforms
       IRIX and Tru64 platforms are working again.  (Some "make test" failures
       remain.)

   Platform-Specific Notes
       EBCDIC
           Special handling is required on EBCDIC platforms to get "qr/[i-j]/"
           to match only "i" and "j", since there are 7 characters between the
           code points for "i" and "j".  This special handling had only been
           invoked when both ends of the range are literals.  Now it is also
           invoked if any of the "\N{...}" forms for specifying a character by
           name or Unicode code point is used instead of a literal.  See
           "Character Ranges" in perlrecharclass.


Internal Changes

       o   SVs of type SVt_NV are now bodyless when a build configure and
           platform allow it, specifically "sizeof(NV) <= sizeof(IV)". The
           bodyless trick is the same one as for IVs since 5.9.2, but for NVs,
           unlike IVs, is not guaranteed on all platforms and build
           configurations.

       o   The $DB::single, $DB::signal and $DB::trace now have set and get
           magic that stores their values as IVs and those IVs are used when
           testing their values in "pp_dbstate".  This prevents perl from
           recursing infinity if an overloaded object is assigned to any of
           those variables. [perl #122445]

       o   "Perl_tmps_grow" which is marked as public API but undocumented has
           been removed from public API. If you use "EXTEND_MORTAL" macro in
           your XS code to preextend the mortal stack, you are unaffected by
           this change.

       o   "cv_name", which was introduced in 5.21.4, has been changed
           incompatibly.  It now has a flags field that allows the caller to
           specify whether the name should be fully qualified.  See "cv_name"
           in perlapi.

       o   Internally Perl no longer uses the "SVs_PADMY" flag.  "SvPADMY()"
           now returns a true value for anything not marked PADTMP.
           "SVs_PADMY" is now defined as 0.

       o   The macros SETsv and SETsvUN have been removed. They were no longer
           used in the core since commit 6f1401dc2a, and have not been found
           present on CPAN.

       o   The "SvFAKE" bit (unused on HVs) got informally reserved by David
           Mitchell for future work on vtables.

       o   The "sv_catpvn_flags" function accepts "SV_CATBYTES" and
           "SV_CATUTF8" flags, which specify whether the appended string is
           bytes or utf8, respectively.

       o   A new opcode class, "METHOP" has been introduced, which holds
           class/method related info needed at runtime to improve performance
           of class/object method calls.

           "OP_METHOD" and "OP_METHOD_NAMED" are moved from being "UNOP/SVOP"
           to being "METHOP".


Selected Bug Fixes

       o   Locking and unlocking values via Hash::Util or
           "Internals::SvREADONLY" no longer has any effect on values that are
           read-only to begin.  Previously, unlocking such values could result
           in crashes, hangs or other erratic behaviour.

       o   The internal "looks_like_number" function (which Scalar::Util
           provides access to) began erroneously to return true for "-e1" in
           5.21.4, affecting also "-'-e1'".  This has been fixed.

       o   The flip-flop operator (".." in scalar context) would return the
           same scalar each time, unless the containing subroutine was called
           recursively.  Now it always returns a new scalar.  [perl #122829]

       o   Some unterminated "(?(...)...)" constructs in regular expressions
           would either crash or give erroneous error messages.  "/(?(1)/" is
           one such example.

       o   "pack "w", $tied" no longer calls FETCH twice.

       o   List assignments like "($x, $z) = (1, $y)" now work correctly if $x
           and $y have been aliased by "foreach".

       o   Some patterns including code blocks with syntax errors, such as "/
           (?{(^{})/", would hang or fail assertions on debugging builds.  Now
           they produce errors.

       o   An assertion failure when parsing "sort" with debugging enabled has
           been fixed.  [perl #122771]

       o   "*a = *b; @a = split //, $b[1]" could do a bad read and produce
           junk results.

       o   In "() = @array = split", the "() =" at the beginning no longer
           confuses the optimizer, making it assume a limit of 1.

       o   Fatal warnings no longer prevent the output of syntax errors.
           [perl #122966]

       o   Fixed a NaN double to long double conversion error on VMS. For
           quiet NaNs (and only on Itanium, not Alpha) negative infinity
           instead of NaN was produced.

       o   Fixed the issue that caused "make distclean" to leave files behind
           that shouldn't. [perl #122820]

       o   AIX now sets the length in "getsockopt" correctly. [perl #120835],
           [rt #91183], [rt #85570].

       o   During the pattern optimization phase, we no longer recurse into
           GOSUB/GOSTART when not SCF_DO_SUBSTR. This prevents the optimizer
           to run "forever" and exhaust all memory. [perl #122283]

       o   t/op/crypt.t now performs SHA-256 algorithm if the default one is
           disabled. [perl #121591]

       o   Fixed an off-by-one error when setting the size of shared array.
           [perl #122950]

       o   Fixed a bug that could cause perl to execute an infinite loop
           during compilation. [perl #122995]


Acknowledgements

       Perl 5.21.5 represents approximately 4 weeks of development since Perl
       5.21.4 and contains approximately 40,000 lines of changes across 530
       files from 33 authors.

       Excluding auto-generated files, documentation and release tools, there
       were approximately 29,000 lines of changes to 390 .pm, .t, .c and .h
       files.

       Perl continues to flourish into its third decade thanks to a vibrant
       community of users and developers. The following people are known to
       have contributed the improvements that became Perl 5.21.5:

       Aaron Crane, Abigail, Alberto Simo~es, Andrew Fresh, Chris 'BinGOs'
       Williams, Craig A. Berry, Dagfinn Ilmari Mannsaaker, Daniel Dragan,
       David Mitchell, Doug Bell, Ed J, Father Chrysostomos, George Greer,
       Graham Knop, James E Keenan, Jarkko Hietaniemi, Karen Etheridge, Karl
       Williamson, Leon Timmermans, Lukas Mai, Niko Tyni, Peter Martini, Petr
       PisaX, Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Shlomi Fish,
       Steve Hay, syber, Tony Cook, Vincent Pit, Yves Orton, AEvar Arnfjoer`
       Bjarmason.

       The list above is almost certainly incomplete as it is automatically
       generated from version control history. In particular, it does not
       include the names of the (very much appreciated) contributors who
       reported issues to the Perl bug tracker.

       Many of the changes included in this version originated in the CPAN
       modules included in Perl's core. We're grateful to the entire CPAN
       community for helping Perl to flourish.

       For a more complete list of all of Perl's historical contributors,
       please see the AUTHORS file in the Perl source distribution.


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 https://rt.perl.org/ .  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.

       If the bug you are reporting has security implications, which make it
       inappropriate to send to a publicly archived mailing list, then please
       send it to perl5-security-report@perl.org.  This points to a closed
       subscription unarchived mailing list, which includes all the core
       committers, who will be able to help assess the impact of issues,
       figure out a resolution, and help co-ordinate the release of patches to
       mitigate or fix the problem across all platforms on which Perl is
       supported.  Please only use this address for security issues in the
       Perl core, not for modules independently distributed on CPAN.


SEE ALSO

       The Changes file for an explanation of how to view 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.



perl v5.22.0                      2015-05-13                PERL5215DELTA(1pm)

perl 5.22 - Generated Fri Aug 14 15:25:21 CDT 2015
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