This document describes differences between the 5.13.6 release and the
       5.13.7 release.

       If you are upgrading from an earlier release such as 5.13.5, first read
       perl5136delta, which describes differences between 5.13.5 and 5.13.6.

Core Enhancements
   Single term prototype
       The "+" prototype is a special alternative to "$" that will act like
       "\[@%]" when given a literal array or hash variable, but will otherwise
       force scalar context on the argument.  This is useful for functions
       which should accept either a literal array or an array reference as the

           sub smartpush (+@) {
               my $aref = shift;
               die "Not an array or arrayref" unless ref $aref eq 'ARRAY';
               push @$aref, @_;

       When using the "+" prototype, your function must check that the
       argument is of an acceptable type.

   "use re '/flags';"
       The "re" pragma now has the ability to turn on regular expression flags
       till the end of the lexical scope:

           use re '/x';
           "foo" =~ / (.+) /;  # /x implied

       See "'/flags' mode" in re for details.

   Statement labels can appear in more places
       Statement labels can now occur before any type of statement or
       declaration, such as "package".

   "use feature "unicode_strings"" now applies to more regex matching
       Another chunk of the "The "Unicode Bug"" in perlunicode is fixed in
       this release.  Now, regular expressions compiled within the scope of
       the "unicode_strings" feature (or under the "u" regex modifier
       (specifiable currently only with infix notation "(?u:...)" or via "use
       re '/u'") will match the same whether or not the target string is
       encoded in utf8, with regard to "[[:posix:]]" character classes

       Work is underway to add the case sensitive matching to the control of
       this feature, but was not complete in time for this dot release.

   Array and hash container functions accept references
       All built-in functions that operate directly on array or hash
       containers now also accept hard references to arrays or hashes:

         | ($k,$v) = each @$arrayref  | ($k,$v) = each $arrayref  |

       This allows these built-in functions to act on long dereferencing
       chains or on the return value of subroutines without needing to wrap
       them in "@{}" or "%{}":

         push @{$obj->tags}, $new_tag;  # old way
         push $obj->tags,    $new_tag;  # new way

         for ( keys %{$hoh->{genres}{artists}} ) {...} # old way
         for ( keys $hoh->{genres}{artists}    ) {...} # new way

       For "push", "unshift" and "splice", the reference will auto-vivify if
       it is not defined, just as if it were wrapped with "@{}".

       Calling "keys" or "values" directly on a reference gives a substantial
       performance improvement over explicit dereferencing.

       For "keys", "values", "each", when overloaded dereferencing is present,
       the overloaded dereference is used instead of dereferencing the
       underlying reftype.  Warnings are issued about assumptions made in the
       following three ambiguous cases:

         (a) If both %{} and @{} overloading exists, %{} is used
         (b) If %{} overloading exists on a blessed arrayref, %{} is used
         (c) If @{} overloading exists on a blessed hashref, @{} is used

       The "/r" flag, which was added to "s///" in 5.13.2, has been extended
       to the "y///" operator.

       It causes it to perform the substitution on a copy of its operand,
       returning that copy instead of a character count.

   New global variable "${^GLOBAL_PHASE}"
       A new global variable, "${^GLOBAL_PHASE}", has been added to allow
       introspection of the current phase of the perl interpreter. It's
       explained in detail in "${^GLOBAL_PHASE}" in perlvar and "BEGIN,
       UNITCHECK, CHECK, INIT and END" in perlmod.

   Unicode Version 6.0 is now supported (mostly)
       Perl comes with the Unicode 6.0 data base updated with Corrigendum #8
       <>, with one exception
       noted below.  See <> for
       details on the new release.  Perl does not support any Unicode
       provisional properties, including the new ones for this release, but
       their database files are packaged with Perl.

       Unicode 6.0 has chosen to use the name "BELL" for the character at
       U+1F514, which is a symbol that looks like a bell, and used in Japanese
       cell phones.  This conflicts with the long-standing Perl usage of
       having "BELL" mean the ASCII "BEL" character, U+0007.  In Perl 5.14,
       "\N{BELL}" will continue to mean U+0007, but its use will generate a
       properties of custom ops in the future. Two new properties have been
       added already, "xop_class" and "xop_peep".

       "xop_class" is one of the OA_*OP constants, and allows B and other
       introspection mechanisms to work with custom ops that aren't BASEOPs.
       "xop_peep" is a pointer to a function that will be called for ops of
       this type from "Perl_rpeep".

       See "Custom Operators" in perlguts and "Custom Operators" in perlapi
       for more detail.

       The old "PL_custom_op_names"/"PL_custom_op_descs" interface is still
       supported but discouraged.

Incompatible Changes
   Dereferencing typeglobs
       If you assign a typeglob to a scalar variable:

           $glob = *foo;

       the glob that is copied to $glob is marked with a special flag
       indicating that the glob is just a copy. This allows subsequent
       assignments to $glob to overwrite the glob. The original glob, however,
       is immutable.

       Many Perl operators did not distinguish between these two types of
       globs.  This would result in strange behaviour in edge cases: "untie
       $scalar" would do nothing if the last thing assigned to the scalar was
       a glob (because it treated it as "untie *$scalar", which unties a
       handle).  Assignment to a glob slot (e.g., "(*$glob) = \@some_array")
       would simply assign "\@some_array" to $glob.

       To fix this, the "*{}" operator (including the *foo and *$foo forms)
       has been modified to make a new immutable glob if its operand is a glob
       copy. Various operators that make a distinction between globs and
       scalars have been modified to treat only immutable globs as globs.

       This causes an incompatible change in code that assigns a glob to the
       return value of "*{}" when that operator was passed a glob copy. Take
       the following code, for instance:

           $glob = *foo;
           *$glob = *bar;

       The *$glob on the second line returns a new immutable glob. That new
       glob is made an alias to *bar. Then it is discarded. So the second
       assignment has no effect.

       It also means that "tie $handle" will now tie $handle as a scalar, even
       if it has had a glob assigned to it.

       The upside to this incompatible change is that bugs [perl #77496]
       <>, [perl
       #77502] <>,
       temporarily while it was being emptied. Consequently, any of its
       subroutines referenced elsewhere would become anonymous (showing up as
       "(unknown)" in "caller"). Now they retain their package names, such
       that "caller" will return the original sub name if there is still a
       reference to its typeglob, or "foo::__ANON__" otherwise [perl #79208]

   "\N{BELL}" is deprecated
       This is because Unicode is using that name for a different character.
       See "Unicode Version 6.0 is now supported (mostly)" for more

Performance Enhancements
       o   When an object has many weak references to it, freeing that object
           can under some some circumstances take O(N^2) time to free (where N
           is the number of references). The number of circumstances has been
           reduced.  [perl #75254]

Modules and Pragmata
   New Modules and Pragmata
       o   The following modules were added by the "Unicode::Collate" upgrade
           from 0.63 to 0.67. See below for details.







   Updated Modules and Pragmata
       o   "Archive::Extract" has been upgraded from 0.44 to 0.46

           Resolves an issue with NetBSD-current and its new unzip executable.

       o   "Archive::Tar" has been upgraded from 1.68 to 1.72

           This adds the ptargrep utility for using regular expressions
           against the contents of files in a tar archive.

       o   "B" has been upgraded from 1.24 to 1.26.

           It no longer crashes when taking apart a "y///" containing
           characters outside the octet range or compiled in a "use utf8"

           The size of the shared object has been reduced by about 40%, with
           newlines embedded in header values.

           The documentation for param_fetch() has been corrected and

       o   "CPAN" has been upgraded from 1.94_61 to 1.94_62

       o   "CPANPLUS" has been upgraded from 0.9007 to 0.9010

           Fixes for the SQLite source engine and resolving of issues with the
           testsuite when run under local::lib and/or cpanminus

       o   "CPANPLUS::Dist::Build" has been upgraded from 0.48 to 0.50

       o   "Data::Dumper" has been upgraded from 2.129 to 2.130_01.

       o   "DynaLoader" has been upgraded from 1.10 to 1.11.

           It fixes a buffer overflow when passed a very long file name.

       o   "ExtUtils::Constant" has been upgraded from 0.22 to 0.23.

           The "AUTOLOAD" helper code generated by
           "ExtUtils::Constant::ProxySubs" can now "croak" for missing
           constants, or generate a complete "AUTOLOAD" subroutine in XS,
           allowing simplification of many modules that use it.  ("Fcntl",
           "File::Glob", "GDBM_File", "I18N::Langinfo", "POSIX", "Socket")

           "ExtUtils::Constant::ProxySubs" can now optionally push the names
           of all constants onto the package's C{@EXPORT_OK}. This has been
           used to replace less space-efficient code in "B", helping
           considerably shrink the size of its shared object.

       o   "Fcntl" has been upgraded from 1.09 to 1.10.

       o   "File::Fetch" has been upgraded from 0.24 to 0.28

           "HTTP::Lite" is now supported for 'http' scheme.

           The "fetch" utility is supported on FreeBSD, NetBSD and Dragonfly
           BSD for the "http" and "ftp" schemes.

       o   "File::Glob" has been upgraded from 1.09 to 1.10.

       o   "File::stat" has been upgraded from 1.03 to 1.04.

           The "-x" and "-X" file test operators now work correctly under the
           root user.

       o   "GDBM_File" has been upgraded from 1.11 to 1.12.

           This fixes a memory leak when DBM filters are used.

       o   "Hash::Util" has been upgraded from 0.09 to 0.10.

       o   "MIME::Base64" has been upgraded from 3.09 to 3.10

           Includes new functions to calculate the length of encoded and
           decoded base64 strings.

       o   "mro" has been upgraded from 1.04 to 1.05.

       o   "NDBM_File" has been upgraded from 1.09 to 1.10.

           This fixes a memory leak when DBM filters are used.

       o   "ODBM_File" has been upgraded from 1.08 to 1.09.

           This fixes a memory leak when DBM filters are used.

       o   "Opcode" has been upgraded from 1.16 to 1.17.

       o   "parent" has been upgraded from 0.223 to 0.224

       o   "Pod::Simple" has been upgraded from 3.14 to 3.15

           Includes various fixes to "HTML" and "XHTML" handling.

       o   "POSIX" has been upgraded from 1.21 to 1.22.

       o   "re" has been upgraded from 0.13 to 0.14, for the sake of the new
           "use re "/flags"" pragma.

       o   "Safe" has been upgraded from 2.28 to 2.29.

           It adds &version::vxs::VCMP to the default share.

       o   "SDBM_File" has been upgraded from 1.07 to 1.08.

       o   "SelfLoader" has been upgraded from 1.17 to 1.18.

           It now works in taint mode [perl #72062]

       o   "Socket" has been upgraded from 1.90 to 1.91.

       o   "Storable" has been upgraded from 2.22 to 2.24

           Includes performance improvement for overloaded classes.

       o   "Sys::Hostname" has been upgraded from 1.13 to 1.14.

       o   "Unicode::Collate" has been upgraded from 0.63 to 0.67

           This release newly adds locales "ja" "ko" and "zh" and its variants
           ( "zh__big5han", "zh__gb2312han", "zh__pinyin", "zh__stroke" ).

           Supported UCA_Version 22 for Unicode 6.0.0.
           kanji (CJK Unified Ideographs) in the JIS X 0208 order.

           "Unicode::Collate::CJK::Korean" which makes tailoring of CJK
           Unified Ideographs in the order of CLDR's Korean ordering.

           "Unicode::Collate::CJK::Pinyin" for "zh__pinyin" which makes
           tailoring of CJK Unified Ideographs in the order of CLDR's pinyin

           "Unicode::Collate::CJK::Stroke" for "zh__stroke" which makes
           tailoring of CJK Unified Ideographs in the order of CLDR's stroke

       perlvar reorders the variables and groups them by topic. Each variable
       introduced after Perl 5.000 notes the first version in which it is
       available. perlvar also has a new section for deprecated variables to
       note when they were removed.

   New Documentation

       New style guide for POD documentation, split mostly from the NOTES
       section of the pod2man man page.

       ( This was added to "v5.13.6" but was not documented with that release

   Changes to Existing Documentation
       o   Array and hash slices in scalar context are now documented in

       o   perlform and perllocale have been corrected to state that "use
           locale" affects formats.

   New Diagnostics
       o   "Using !~ with %s doesn't make sense": This message was actually
           added in 5.13.2, but was omitted from perldelta. It now applies
           also to the "y///" operator, and has been documented.

Utility Changes

       o   ptargrep is a utility to apply pattern matching to the contents of
           files in a tar archive. It comes with "Archive::Tar".

       o   The new t/mro/isa_aliases.t has been added, which tests that
           "*Foo::ISA = *Bar::ISA" works properly.

       o   t/mro/isarev.t has been added, which tests that "PL_isarev"
           (accessible at the Perl level via "mro::get_isarev") is updated

           Support for building with Visual C++ 2010 is now underway, but is
           not yet complete. See README.win32 for more details.

       VMS Record-oriented files (record format variable or variable with
           fixed control) opened for write by the perlio layer will now be
           line buffered to prevent the introduction of spurious line breaks
           whenever the perlio buffer fills up.

Internal Changes
       o   "lex_start" has been added to the API, but is considered

       o   A new "parse_block" function has been added to the API [perl
           #78222] <>.

       o   A new, experimental API has been added for accessing the internal
           structure that Perl uses for "%^H". See the functions beginning
           with "cophh_" in perlapi.

       o   A stash can now have a list of effective names in addition to its
           usual name. The first effective name can be accessed via the
           "HvENAME" macro, which is now the recommended name to use in MRO
           linearisations ("HvNAME" being a fallback if there is no

           These names are added and deleted via "hv_ename_add" and
           "hv_ename_delete". These two functions are not part of the API.

       o   The way the parser handles labels has been cleaned up and
           refactored. As a result, the "newFOROP()" constructor function no
           longer takes a parameter stating what label is to go in the state

       o   The "newWHILEOP()" and "newFOROP()" functions no longer accept a
           line number as a parameter.

       o   A new "parse_barestmt()" function has been added, for parsing a
           statement without a label.

       o   A new "parse_label()" function has been added, that parses a
           statement label, separate from statements.

       o   The "CvSTASH()" macro can now only be used as an rvalue.
           "CvSTASH_set()" has been added to replace assignment to
           "CvSTASH()". This is to ensure that backreferences are handled
           properly. These macros are not part of the API.

       o   The "op_scope()" and "op_lvalue()" functions have been added to the
           API, but are considered experimental.

Selected Bug Fixes
       o   The "parse_stmt" C function added in earlier in the 5.13.x series
           has been fixed to work with statements ending with "}" [perl

       o   The "(?d)" regular expression construct now overrides a previous
           "(?u)" or "use feature "unicode_string"" [perl #78508]

       o   A memory leak in "do "file"", introduced in perl 5.13.6, has been
           fixed [perl #78488]

       o   Various bugs related to typeglob dereferencing have been fixed. See
           "Dereferencing typeglobs", above.

       o   The "SvPVbyte" function available to XS modules now calls magic
           before downgrading the SV, to avoid warnings about wide characters
           [perl #72398]

       o   The "=" operator used to ignore magic (e.g., tie methods) on its
           right-hand side if the scalar happened to hold a typeglob. This
           could happen if a typeglob was the last thing returned from or
           assigned to a tied scalar [perl #77498]

       o   "sprintf" was ignoring locales when called with constant arguments
           [perl #78632]

       o   A non-ASCII character in the Latin-1 range could match both a Posix
           class, such as "[[:alnum:]]", and its inverse "[[:^alnum:]]".  This
           is now fixed for regular expressions compiled under the "u"
           modifier.  See ""use feature "unicode_strings"" now applies to more
           regex matching".  [perl #18281]

       o   Concatenating long strings under "use encoding" no longer causes
           perl to crash [perl #78674]

       o   Typeglob assignments would crash if the glob's stash no longer
           existed, so long as the glob assigned to was named 'ISA' or the
           glob on either side of the assignment contained a subroutine.

       o   Calling "->import" on a class lacking an import method could
           corrupt the stack, resulting in strange behaviour. For instance,

             push @a, "foo", $b = bar->import;

           would assign 'foo' to $b [perl #63790]

       o   Creating an alias to a package when that package had been detached
           from the symbol table would result in corrupted isa caches [perl
           #77358] <>.

       o   ".=" followed by "<>" or "readline" would leak memory if $/
           This bug was introduced in 5.13.2 and did not affect earlier perl

       o   Matching a Unicode character against an alternation containing
           characters that happened to match continuation bytes in the
           former's UTF8 representation ("qq{\x{30ab}} =~ /\xab|\xa9/") would
           cause erroneous warnings [perl #70998]

       o   "s///r" (added in 5.13.2) no longer leaks.

       o   The trie optimisation was not taking empty groups into account,
           preventing 'foo' from matching "/\A(?:(?:)foo|bar|zot)\z/" [perl
           #78356] <>.

       o   A pattern containing a "+" inside a lookahead would sometimes cause
           an incorrect match failure in a global match (e.g., "/(?=(\S+))/g")
           [perl #68564]

       o   Iterating with "foreach" over an array returned by an lvalue sub
           now works [perl #23790]

       o   $@ is now localised during calls to "binmode" to prevent action at
           a distance [perl #78844]

       o   "PL_isarev", which is accessible to Perl via "mro::get_isarev" is
           now updated properly when packages are deleted or removed from the
           @ISA of other classes. This allows many packages to be created and
           deleted without causing a memory leak [perl #75176]

       o   "undef *Foo::" and "undef *Foo::ISA" and "delete $package::{ISA}"
           used not to update the internal isa caches if the stash or @ISA
           array had a reference elsewhere. In fact, "undef *Foo::ISA" would
           stop a new @Foo::ISA array from updating caches.

       o   @ISA arrays can now be shared between classes via "*Foo::ISA =
           \@Bar::ISA" or "*Foo::ISA = *Bar::ISA" [perl #77238]

       o   The parser no longer hangs when encountering certain Unicode
           characters, such as U+387 [perl #74022]

       o   "formline" no longer crashes when passed a tainted format picture.
           It also taints $^A now if its arguments are tainted [perl #79138]

       o   A signal handler called within a signal handler could cause leaks
           or double-frees. Now fixed.  [perl #76248]

       Perl 5.13.7 represents approximately one month of development since
       Perl 5.13.6 and contains 73100 lines of changes across 518 files from
       39 authors and committers:

       Abhijit Menon-Sen, Abigail, Ben Morrow, Chas. J. Owens IV, Chris
       'BinGOs' Williams, Craig A. Berry, David Golden, David Mitchell, Father
       Chrysostomos, Fingle Nark, Florian Ragwitz, George Greer, Grant McLean,
       H.Merijn Brand, Ian Goodacre, Jan Dubois, Jerry D. Hedden, Jesse
       Vincent, Karl Williamson, Lubomir Rintel, Marty Pauley, Moritz Lenz,
       Nicholas Clark, Nicolas Kaiser, Niko Tyni, Peter John Acklam, Rafael
       Garcia-Suarez, Shlomi Fish, Steffen Mueller, Steve Hay, Tatsuhiko
       Miyagawa, Tim Bunce, Todd Rinaldo, Tom Christiansen, Tom Hukins, Tony
       Cook, Yves Orton, Zefram and brian d foy

       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.

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 .  There may also be
       information at , 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 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 This points to a closed
       subscription unarchived mailing list, which includes all the core
       committers, who 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.

       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.
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