=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>
+the core. In regular expressions you can now use the special escape C<\K>
as a way to do something like floating length positive lookbehind. It is
also useful in substitutions like:
=head2 The C<_> prototype
-A new prototype character has been added. C<_> is equivalent to C<$> (it
-denotes a scalar), but defaults to C<$_> 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.
+A new prototype character has been added. C<_> is equivalent to C<$> but
+defaults to C<$_> if the corresponding argument isn't supplied. (both C<$>
+and <_> denote a scalar). Due to the optional nature of the argument, you
+can only use it at the end of a prototype, or before a semicolon.
This has a small incompatible consequence: the prototype() function has
been adjusted to return C<_> for some built-ins in appropriate cases (for
To use state variables, one needs to enable them by using
- use feature "state";
+ use feature 'state';
or by using the C<-E> command-line switch in one-liners.
See L<perlsub/"Persistent variables via state()">.
See L<< UNIVERSAL/"$obj->DOES( ROLE )" >>.
-=head2 C<CLONE_SKIP()>
-
-Perl has now support for the C<CLONE_SKIP> special subroutine. Like
-C<CLONE>, C<CLONE_SKIP> is called once per package; however, it is called
-just before cloning starts, and in the context of the parent thread. If it
-returns a true value, then no objects of that class will be cloned. See
-L<perlmod> for details. (Contributed by Dave Mitchell.)
-
=head2 Formats
Formats were improved in several ways. A new field, C<^*>, can be used for
The constant folding routine is now wrapped in an exception handler, and
if folding throws an exception (such as attempting to evaluate 0/0), perl
now retains the current optree, rather than aborting the whole program.
-(Nicholas Clark, Dave Mitchell)
+Without this change, programs would not compile if they had expressions that
+happened to generate exceptions, even though those expressions were in code
+that could never be reached at runtime. (Nicholas Clark, Dave Mitchell)
=head2 Source filters in @INC
=head2 MAD
-MAD, which stands for I<Misc Attribute Decoration>, is a
+MAD, which stands for I<Miscellaneous Attribute Decoration>, is a
still-in-development work leading to a Perl 5 to Perl 6 converter. To
enable it, it's necessary to pass the argument C<-Dmad> to Configure. The
-obtained perl isn't binary compatible with a regular perl 5.9.4, and has
+obtained perl isn't binary compatible with a regular perl 5.10, and has
space and speed penalties; moreover not all regression tests still pass
with it. (Larry Wall, Nicholas Clark)
that the data is to be processed in character mode, i.e. character by
character; on the contrary, C<U0> in unpack() indicates UTF-8 mode, where
the packed string is processed in its UTF-8-encoded Unicode form on a byte
-by byte basis. This is reversed with regard to perl 5.8.X.
+by byte basis. This is reversed with regard to perl 5.8.X, but now consistent
+between pack() and unpack().
Moreover, C<C0> and C<U0> can also be used in pack() templates to specify
respectively character and byte modes.
=head2 strictures and dereferencing in defined()
-C<use strict "refs"> was ignoring taking a hard reference in an argument
+C<use strict 'refs'> was ignoring taking a hard reference in an argument
to defined(), as in :
- use strict "refs";
- my $x = "foo";
+ use strict 'refs';
+ my $x = 'foo';
if (defined $$x) {...}
This now correctly produces the run-time error C<Can't use string as a
use warnings;
require Carp;
- Carp::confess "argh";
+ Carp::confess 'argh';
=item C<less>
It can also display the parent inheritance tree of a given class, with the
C<i> command.
-Perl has a new -dt command-line flag, which enables threads support in the
-debugger.
-
=item ptar
C<ptar> is a pure perl implementation of C<tar>, that comes with
=item ptardiff
-C<ptardiff> is a small script used to generate a diff between the contents
+C<ptardiff> is a small utility used to generate a diff between the contents
of a tar archive and a directory tree. Like C<ptar>, it comes with
C<Archive::Tar>.
=item h2ph and h2xs
-C<h2ph> and C<h2xs> have been made a bit more robust with regard to
+C<h2ph> and C<h2xs> have been made more robust with regard to
"modern" C code.
C<h2xs> implements a new option C<--use-xsloader> to force use of
=item cpanp
-C<cpanp>, the CPANPLUS shell, has been added. (C<cpanp-run-perl>, an
+C<cpanp>, the CPANPLUS shell, has been added. (C<cpanp-run-perl>, a
helper for CPANPLUS operation, has been added too, but isn't intended for
direct use).
=item PERLIO_DEBUG
-The C<PERLIO_DEBUG> environment variable has no longer any effect for
+The C<PERLIO_DEBUG> environment variable no longer has any effect for
setuid scripts and for scripts run with B<-T>.
Moreover, with a thread-enabled perl, using C<PERLIO_DEBUG> could lead to
=item C<-t> switch fix
The C<-w> and C<-t> switches can now be used together without messing
-up what categories of warnings are activated or not. (Rafael)
+up which categories of warnings are activated. (Rafael)
=item Duping UTF-8 filehandles
ordering. (The inheritance hierarchy of C<B::*> objects has been changed
to reflect this.)
+=head2 Elimination of SVt_PVBM
+
+Related to this, the internal type C<SVt_PVBM> has been been removed. This
+dedicated type of C<SV> was used by the C<index> operator and parts of the
+regexp engine to facilitate fast Boyer-Moore matches. Its use internally has
+been replaced by C<SV>s of type C<SVt_PVGV>.
+
+=head2 New type SVt_BIND
+
+A new type C<SVt_BIND> has been added, in readiness for the project to
+implement Perl 6 on 5. There deliberately is no implementation yet, and
+they cannot yet be created or destroyed.
+
=head2 Removal of CPP symbols
The C preprocessor symbols C<PERL_PM_APIVERSION> and
=head2 Less space is used by ops
The C<BASEOP> structure now uses less space. The C<op_seq> field has been
-removed and replaced by the one-bit fields C<op_opt>. C<op_type> is now 9
+removed and replaced by a single bit bit-field C<op_opt>. C<op_type> is now 9
bits long. (Consequently, the C<B::OP> class doesn't provide an C<seq>
method anymore.)
=head2 $^H and %^H
The implementation of the special variables $^H and %^H has changed, to
-allow implementing lexical pragmas in pure perl.
+allow implementing lexical pragmas in pure Perl.
=head2 B:: modules inheritance changed
=for p5p XXX have we some docs on how to create regexp engine plugins, since that's now possible ? (perlreguts)
-=for p5p XXX new BIND SV type, #29544, #29642
-
=head1 Known Problems
There's still a remaining problem in the implementation of the lexical
projects / p5sagit/p5-mst-13.2.git / commitdiff