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pod /=head1 NAME
perl5101delta - what is new for perl v5.10.1
=head1 DESCRIPTION
This document describes differences between the 5.10.0 release and
the 5.10.1 release.
If you are upgrading from an earlier release such as 5.8.8, first read
the L
, which describes differences between 5.8.8 and
5.10.0
=head1 Incompatible Changes
=head2 Switch statement changes
The handling of complex expressions by the C/C switch
statement has been enhanced. There are two new cases where C now
interprets its argument as a boolean, instead of an expression to be used
in a smart match:
=over 4
=item flip-flop operators
The C<..> and C<...> flip-flop operators are now evaluated in boolean
context, following their usual semantics; see L.
Note that, as in perl 5.10.0, C will not work to test
whether a given value is an integer between 1 and 10; you should use
C instead (note the array reference).
However, contrary to 5.10.0, evaluating the flip-flop operators in boolean
context ensures it can now be useful in a C, notably for
implementing bistable conditions, like in:
when (/^=begin/ .. /^=end/) {
# do something
}
=item defined-or operator
A compound expression involving the defined-or operator, as in
C, will be treated as boolean if the first
expression is boolean. (This just extends the existing rule that applies
to the regular or operator, as in C.)
=back
The next section details more changes brought to the semantics to
the smart match operator, that naturally also modify the behaviour
of the switch statements where smart matching is implicitly used.
=head2 Smart match changes
=head3 Changes to type-based dispatch
The smart match operator C<~~> is no longer commutative. The behaviour of
a smart match now depends primarily on the type of its right hand
argument. Moreover, its semantics have been adjusted for greater
consistency or usefulness in several cases. While the general backwards
compatibility is maintained, several changes must be noted:
=over 4
=item *
Code references with an empty prototype are no longer treated specially.
They are passed an argument like the other code references (even if they
choose to ignore it).
=item *
C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
returns a true value for each key of the hash (or element of the
array), instead of passing the whole hash or array as a reference to
the subroutine.
=item *
Due to the commutativity breakage, code references are no longer
treated specially when appearing on the left of the C<~~> operator,
but like any vulgar scalar.
=item *
C is always false (since C can't be a key in a
hash). No implicit conversion to C<""> is done (as was the case in perl
5.10.0).
=item *
C<$scalar ~~ @array> now always distributes the smart match across the
elements of the array. It's true if one element in @array verifies
C<$scalar ~~ $element>. This is a generalization of the old behaviour
that tested whether the array contained the scalar.
=back
The full dispatch table for the smart match operator is given in
L.
=head3 Smart match and overloading
According to the rule of dispatch based on the rightmost argument type,
when an object overloading C<~~> appears on the right side of the
operator, the overload routine will always be called (with a 3rd argument
set to a true value, see L.) However, when the object will
appear on the left, the overload routine will be called only when the
rightmost argument is a simple scalar. This way distributivity of smart match
across arrays is not broken, as well as the other behaviours with complex
types (coderefs, hashes, regexes). Thus, writers of overloading routines
for smart match mostly need to worry only with comparing against a scalar,
and possibly with stringification overloading; the other common cases
will be automatically handled consistently.
C<~~> will now refuse to work on objects that do not overload it (in order
to avoid relying on the object's underlying structure). (However, if the
object overloads the stringification or the numification operators, and
if overload fallback is active, it will be used instead, as usual.)
=head2 Other incompatible changes
=over 4
=item *
The semantics of C have changed slightly.
See L<"Modules and Pragmata"> for more information.
=item *
It is now a run-time error to use the smart match operator C<~~>
with an object that has no overload defined for it. (This way
C<~~> will not break encapsulation by matching against the
object's internal representation as a reference.)
=item *
The version control system used for the development of the perl
interpreter has been switched from Perforce to git. This is mainly an
internal issue that only affects people actively working on the perl core;
but it may have minor external visibility, for example in some of details
of the output of C. See L for more information.
=item *
The internal structure of the C whose source was
stored under F
F parameter. Specifically, this change does not by default
alter the location of any files in the final installation.
=item *
As part of the C 2.x to 3.x upgrade, the experimental
C module has been removed.
See L for more details.
=item *
As part of the C upgrade, the
C and C modules
have been removed from this distribution.
=item *
C no longer contains the C<%:patchlevel> hash.
=item *
This one is actually a change introduced in 5.10.0, but it was missed
from that release's perldelta, so it is mentioned here instead.
A bugfix related to the handling of the C modifier and C resulted
in a change of behaviour between 5.8.x and 5.10.0:
# matches in 5.8.x, doesn't match in 5.10.0
$re = qr/^bar/; "foo\nbar" =~ /$re/m;
=back
=head1 Core Enhancements
=head2 Unicode Character Database 5.1.0
The copy of the Unicode Character Database included in Perl 5.10.1 has
been updated to 5.1.0 from 5.0.0. See
L for the
notable changes.
=head2 A proper interface for pluggable Method Resolution Orders
As of Perl 5.10.1 there is a new interface for plugging and using method
resolution orders other than the default (linear depth first search).
The C3 method resolution order added in 5.10.0 has been re-implemented as
a plugin, without changing its Perl-space interface. See L for
more information.
=head2 The C pragma
This pragma allows you to lexically disable or enable overloading
for some or all operations. (Yuval Kogman)
=head2 Parallel tests
The core distribution can now run its regression tests in parallel on
Unix-like platforms. Instead of running C, set C in
your environment to the number of tests to run in parallel, and run
C. On a Bourne-like shell, this can be done as
TEST_JOBS=3 make test_harness # Run 3 tests in parallel
An environment variable is used, rather than parallel make itself, because
L needs to be able to schedule individual non-conflicting test
scripts itself, and there is no standard interface to C utilities to
interact with their job schedulers.
Note that currently some test scripts may fail when run in parallel (most
notably C). If necessary run just the failing scripts
again sequentially and see if the failures go away.
=head2 DTrace support
Some support for DTrace has been added. See "DTrace support" in F.
=head2 Support for C in CPAN module metadata
Both C and C now support the C keyword
in the C metadata file included in most recent CPAN distributions.
This allows distribution authors to specify configuration prerequisites that
must be installed before running F or F.
See the documentation for C or C for more
on how to specify C when creating a distribution for CPAN.
=head1 Modules and Pragmata
=head2 New Modules and Pragmata
=over 4
=item C
This is a new lexically-scoped alternative for the C module.
The bundled version is 2.06_01. Note that in this release, using a string
eval when C is in effect can cause the autodie behaviour to leak
into the surrounding scope. See L for more details.
=item C
This has been added to the core (version 2.020).
=item C
This pragma establishes an ISA relationship with base classes at compile
time. It provides the key feature of C
This has been added to the core (version 1.39).
=back
=head2 Pragmata Changes
=over 4
=item C
Upgraded from version 0.08 to 0.09.
=item C
Upgraded from version 1.02 to 1.03.
=item C for a replacement.
=item C
Upgraded from version 0.22 to 0.23.
=item C
Upgraded from version 0.22 to 0.23.
=item C
Upgraded from version 0.22 to 0.23.
=item C
Upgraded from version 1.06 to 1.07.
The Unicode F database file has been added. This has the
effect of adding some extra C<\N> character names that formerly wouldn't
have been recognised; for example, C<"\N{LATIN CAPITAL LETTER GHA}">.
=item C
Upgraded from version 1.13 to 1.17.
=item C
The meaning of the C<:5.10> and C<:5.10.X> feature bundles has
changed slightly. The last component, if any (i.e. C) is simply ignored.
This is predicated on the assumption that new features will not, in
general, be added to maintenance releases. So C<:5.10> and C<:5.10.X>
have identical effect. This is a change to the behaviour documented for
5.10.0.
=item C
Upgraded from version 2.13 to 2.14 (this was just a version bump; there
were no functional changes).
=item C
Upgraded from version 0.5565 to 0.62.
=item C
Upgraded from version 1.06 to 1.07.
=item C
Upgraded from version 1.06 to 1.07.
=item C
See L pragma"> above.
=item C
Upgraded from version 0.74 to 0.77.
=back
=head2 Updated Modules
=over 4
=item C
Upgraded from version 0.24 to 0.34.
=item C
Upgraded from version 1.38 to 1.52.
=item C
Upgraded from version 0.79 to 0.85.
=item C
Upgraded from version 5.63 to 5.68.
=item C
Upgraded from version 1.05 to 1.06.
=item C
Upgraded from version 1.17 to 1.22.
=item C
Upgraded from version 1.05 to 1.11.
=item C
Upgraded from version 0.83 to 0.89.
=item C
Upgraded from version 1.09 to 1.11.
=item C
Upgraded from version 1.01 to 1.02.
=item C
Upgraded from version 1.10 to 1.11.
=item C
Upgraded from version 1.08 to 1.11.
=item C
Upgraded from version 3.29 to 3.43.
(also includes the "default_value for popup_menu()" fix from 3.45).
=item C
Upgraded from version 2.008 to 2.020.
=item C
Upgraded from version 1.9205 to 1.9402. C has a local fix to
stop it being too verbose on download failure.
=item C
Upgraded from version 0.84 to 0.88.
=item C
Upgraded from version 0.06_02 to 0.36.
=item C
Upgraded from version 3.25_01 to 3.30.
=item C
Upgraded from version 2.121_14 to 2.124.
=item C
Upgraded from version 1.01 to 1.02.
=item C
Upgraded from version 1.816_1 to 1.820.
=item C
Upgraded from version 3.13 to 3.19.
=item C
Upgraded from version 2.36_01 to 2.39.
=item C
Upgraded from version 5.45 to 5.47.
=item C
Upgraded from version 1.01 to 1.03.
=item C
Upgraded from version 1.12 to 1.13.
=item C
Upgraded from version 1.08 to 1.10.
=item C
Upgraded from version 2.23 to 2.35.
=item C
Upgraded from version 1.10 to 1.11.
=item C
Upgraded from version 5.62 to 5.63.
=item C
Upgraded from version 0.21 to 0.2602.
=item C
Upgraded from version 1.13 to 1.16.
=item C
Upgraded from 0.20 to 0.22. (Note that neither of these versions are
available on CPAN.)
=item C
Upgraded from version 1.27 to 1.28.
=item C
Upgraded from version 1.44 to 1.54.
=item C
Upgraded from version 6.42 to 6.55_02.
Note that C and C
have been removed from this distribution.
=item C
Upgraded from version 1.51_01 to 1.56.
=item C
Upgraded from version 2.18_02 to 2.2002.
=item C
Upgraded from version 1.05 to 2.06_01. See also the new pragma C.
=item C
Upgraded from version 2.76 to 2.77.
=item C
Upgraded from version 1.1005 to 1.1006.
=item C
Upgraded from version 2.11 to 2.14.
=item C
Upgraded from version 0.14 to 0.20.
=item C
Upgraded from version 1.12 to 1.14.
=item C
Upgraded from version 2.04 to 2.07_03.
=item C
Upgraded from version 3.2501 to 3.30.
=item C
Upgraded from version 1.00 to 1.01.
=item C
Upgraded from version 0.18 to 0.22.
=item C
Upgraded from version 1.07 to 1.08.
=item C
Upgraded from version 2.01 to 2.02.
=item C
Upgraded from version 0.82 to 0.84.
=item C
Upgraded from version 1.07 to 1.08.
=item C
Upgraded from version 1.49 to 1.50.
=item C
Upgraded from version 1.08 to 1.09.
=item C
Upgraded from version 2.37 to 2.38.
=item C
Upgraded from version 1.03 to 1.04. This fixes a memory leak.
=item C
Upgraded from version 1.00 to 1.01.
=item C
Upgraded from version 1.23_01 to 1.25.
This makes non-blocking mode work on Windows in C
[CPAN #43573].
=item C
Upgraded from version 2.008 to 2.020.
=item C
Upgraded from version 1.06 to 1.07.
=item C
Upgraded from version 1.27 to 1.28.
=item C
Upgraded from version 1.30_01 to 1.31.
=item C
Upgraded from version 1.07 to 1.09.
=item C
Upgraded from version 0.40_1 to 0.46.
=item C
Upgraded from version 1.02 to 1.04.
=item C
Upgraded from version 1.05 to 2.01.
=item C
Upgraded from version 0.5565 to 0.62.
=item C
Upgraded from version 1.19 to 1.21.
=item C
Upgraded from version 1.12 to 1.13.
=item C
Upgraded from version 0.01 to 0.02.
=item C
Upgraded from version 1.59 to 1.60.
=item C
Upgraded from version 1.88 to 1.89.
=item C
Upgraded from version 0.16 to 0.19.
=item C
Upgraded from version 0.21 to 0.22.
=item C
Upgraded from version 1.37 to 1.56.
=item C
Upgraded from version 1.04 to 1.20.
=item C
Upgraded from version 1.01_02 to 1.01_03 (just a minor documentation
change).
=item C
Upgraded from version 0.2808_01 to 0.34_02.
=item C
Upgraded from version 2.13 to 2.18. This release no longer contains the
C<%Module::CoreList::patchlevel> hash.
=item C
Upgraded from version 0.12 to 0.16.
=item C
Upgraded from version 0.22 to 0.30.
=item C
Upgraded from version 0.01 to 0.02.
=item C
Upgraded from version 3.6 to 3.9.
=item C
Upgraded from version 1.07 to 1.08.
=item C
Upgraded from version 2.33 to 2.36.
=item C
Upgraded from version 0.60_01 to 0.64.
=item C
Upgraded from version 0.32 to 0.34.
=item C
Upgraded from version 1.03 to 1.04.
=item C
Upgraded from version 0.01 to 0.02.
=item C
Upgraded from version 1.04 to 1.06.
=item C
Upgraded from version 0.04 to 0.07.
=item C
Upgraded from version 2.16 to 2.22.
=item C
Upgraded from version 1.35 to 1.37.
=item C
Upgraded from version 3.05 to 3.07.
=item C
Upgraded from version 3.08 to 3.13.
=item C
Upgraded from version 1.13 to 1.17.
=item C
Upgraded from 2.12 to 2.18.
=item C
Upgraded from version 1.19 to 1.21.
=item C
Upgraded from 1.01 to 1.02.
=item C
Upgraded from 1.11 to 1.17.
=item C
Upgraded from 1.80 to 1.82.
=item C
Upgraded from 2.18 to 2.20.
=item C
Upgraded from version 2.13 to 2.14. Please see L.
=item C
Upgraded from version 1.06 to 1.07.
=item C
Upgraded from version 0.22 to 0.27.
=item C
Upgraded from version 1.12 to 2.00.
=item C
Upgraded from version 1.03 to 1.04.
=item C
Upgraded from version 0.18 to 0.20.
=item C
Upgraded from version 2.64 to 3.17.
Note that one side-effect of the 2.x to 3.x upgrade is that the
experimental C module (and its supporting
C, C, C and C modules) have been
removed. If you still need this, then they are available in the
(unmaintained) C distribution on CPAN.
=item C
Upgraded from version 0.72 to 0.92.
=item C
Upgraded from version 3.26 to 3.27.
=item C
Upgraded from version 2007.1117 to 2009.0305.
=item C
Upgraded from version 2006.1117 to 2009.0305.
=item C
Upgraded from version 2.00 to 2.11.
=item C
Upgraded from version 2.01 to 2.09.
=item C
Upgraded from version 1.67 to 1.72.
=item C
Upgraded from version 1.14 to 1.29.
=item C
Upgraded from version 1.37 to 1.38.
=item C
This has documentation changes, and has been assigned a version for the
first time: version 4.2.
=item C
Upgraded from version 1.9711 to 1.9719.
=item C
Upgraded from version 1.18 to 1.1901.
=item C
Upgraded from version 1.12 to 1.15.
=item C
Upgraded from version 1.02 to 1.03.
=item C
Upgraded from version 0.25 to 0.27.
C now works on Unified CJK code points added to later versions
of Unicode.
C has new fields returned to provide both a simpler interface
and previously missing information. The old fields are retained for
backwards compatibility. Information about Turkic-specific code points is
now returned.
The documentation has been corrected and expanded.
=item C
Upgraded from version 1.04 to 1.05.
=item C
Upgraded from version 0.34 to 0.39.
=item C
Upgraded from version 0.1001_01 to 0.1101.
=item C
Upgraded from version 0.08 to 0.10.
=back
=head1 Utility Changes
=over 4
=item F
Now looks in C too, which is a recent addition to gcc's
search path.
=item F
No longer incorrectly treats enum values like macros (Daniel Burr).
Now handles C++ style constants (C) properly in enums. (A patch from
Rainer Weikusat was used; Daniel Burr also proposed a similar fix).
=item F
C subroutines now work under the debugger.
The debugger now correctly handles proxy constant subroutines, and
subroutine stubs.
=item F
Perl 5.10.1 adds a new utility F, which is a variant of
F, but for sending non-bug-reports to the authors and maintainers
of Perl. Getting nothing but bug reports can become a bit demoralising:
we'll see if this changes things.
=back
=head1 New Documentation
=over 4
=item L
This contains instructions on how to build perl for the Haiku platform.
=item L
This describes the new interface for pluggable Method Resolution Orders.
=item L
This document, by Richard Foley, provides an introduction to the use of
performance and optimization techniques which can be used with particular
reference to perl programs.
=item L
This describes how to access the perl source using the I version
control system.
=item L
This describes the new F utility.
=back
=head1 Changes to Existing Documentation
The various large C files (which listed every change made to perl
over the last 18 years) have been removed, and replaced by a small file,
also called C, which just explains how that same information may
be extracted from the git version control system.
The file F has been deleted, as it mainly described
interacting with the old Perforce-based repository, which is now obsolete.
Information still relevant has been moved to L.
L, L, L and L are now all
generated at build time, rather than being shipped as part of the release.
=head1 Performance Enhancements
=over 4
=item *
A new internal cache means that C will often be faster.
=item *
Under C, the locale-relevant information is now cached on
read-only values, such as the list returned by C. This makes
operations such as C in the scope of C much
faster.
=item *
Empty C methods are no longer called.
=back
=head1 Installation and Configuration Improvements
=head2 F has been revised. Specifically, all
extensions are now flat, and at the top level, with C in pathnames
replaced by C<->, so that F, and as
reported by C<%Config::Config> under the keys C,
C, C and C have not changed, and
still use C. Hence this change will not have any affect once perl is
installed. However, C, C and C have now
become extensions in their own right, so if you run F with
options to specify an exact list of extensions to build, you will need to
change it to account for this.
For 5.10.2, it is planned that many dual-life modules will have been moved
from F