=head1 NAME
-perldelta - what is new for perl 5.10.0
+perl5100delta - what is new for perl 5.10.0
=head1 DESCRIPTION
< # match an opening angle bracket
(?: # match one of:
(?> # don't backtrack over the inside of this group
- [^<>]+ # one or more non angle brackets
+ [^<>]+ # one or more non angle brackets
) # end non backtracking group
| # ... or ...
(?1) # recurse to bracket 1 and try it again
C<\R> matches a generic linebreak, that is, vertical whitespace, plus
the multi-character sequence C<"\x0D\x0A">.
+=item Optional pre-match and post-match captures with the /p flag
+
+There is a new flag C</p> for regular expressions. Using this
+makes the engine preserve a copy of the part of the matched string before
+the matching substring to the new special variable C<${^PREMATCH}>, the
+part after the matching substring to C<${^POSTMATCH}>, and the matched
+substring itself to C<${^MATCH}>.
+
+Perl is still able to store these substrings to the special variables
+C<$`>, C<$'>, C<$&>, but using these variables anywhere in the program
+adds a penalty to all regular expression matches, whereas if you use
+the C</p> flag and the new special variables instead, you pay only for
+the regular expressions where the flag is used.
+
+For more detail on the new variables, see L<perlvar>; for the use of
+the regular expression flag, see L<perlop> and L<perlre>.
+
=back
=head2 C<say()>
=head2 The C<_> prototype
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<$>
-and C<_> denote a scalar). Due to the optional nature of the argument, you
-can only use it at the end of a prototype, or before a semicolon.
+defaults to C<$_> if the corresponding argument isn't supplied (both C<$>
+and C<_> denote a scalar). Due to the optional nature of the argument,
+you can only use it at the end of a prototype, or before a semicolon.
This has a small incompatible consequence: the prototype() function has
been adjusted to return C<_> for some built-ins in appropriate cases (for
use feature 'state';
or by using the C<-E> command-line switch in one-liners.
-See L<perlsub/"Persistent variables via state()">.
+See L<perlsub/"Persistent Private Variables">.
=head2 Stacked filetest operators
This variable gives the native status returned by the last pipe close,
backtick command, successful call to wait() or waitpid(), or from the
-system() operator. See L<perlrun> for details. (Contributed by Gisle Aas.)
+system() operator. See L<perlvar> for details. (Contributed by Gisle Aas.)
=item C<${^RE_TRIE_MAXBUF}>
=head2 kill() on Windows
On Windows platforms, C<kill(-9, $pid)> now kills a process tree.
-(On UNIX, this delivers the signal to all processes in the same process
+(On Unix, this delivers the signal to all processes in the same process
group.)
=head1 Incompatible Changes
use of the recursive inheritance while resolving a method or doing a
C<$foo-E<gt>isa($bar)> lookup.
+=head2 warnings::enabled and warnings::warnif changed to favor users of modules
+
+The behaviour in 5.10.x favors the person using the module;
+The behaviour in 5.8.x favors the module writer;
+
+Assume the following code:
+
+ main calls Foo::Bar::baz()
+ Foo::Bar inherits from Foo::Base
+ Foo::Bar::baz() calls Foo::Base::_bazbaz()
+ Foo::Base::_bazbaz() calls: warnings::warnif('substr', 'some warning
+message');
+
+On 5.8.x, the code warns when Foo::Bar contains C<use warnings;>
+It does not matter if Foo::Base or main have warnings enabled
+to disable the warning one has to modify Foo::Bar.
+
+On 5.10.0 and newer, the code warns when main contains C<use warnings;>
+It does not matter if Foo::Base or Foo::Bar have warnings enabled
+to disable the warning one has to modify main.
+
=head1 Modules and Pragmata
=head2 Upgrading individual core modules
=item *
C<Archive::Extract> is a generic archive extraction mechanism
-for F<.tar> (plain, gziped or bzipped) or F<.zip> files.
+for F<.tar> (plain, gzipped or bzipped) or F<.zip> files.
=item *
The new compilation flag C<PERL_DONT_CREATE_GVSV>, introduced as an option
in perl 5.8.8, is turned on by default in perl 5.9.3. It prevents perl
-from creating an empty scalar with every new typeglob. See L<perl588delta>
+from creating an empty scalar with every new typeglob. See L<perl589delta>
for details.
=head2 Weak references are cheaper
=head2 Elimination of SVt_PVBM
-Related to this, the internal type C<SVt_PVBM> has been been removed. This
+Related to this, the internal type C<SVt_PVBM> has 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>.
https://perl5.git.perl.org / perl5.git / blobdiff