package MRO::Compat;
use strict;
use warnings;
+require 5.006_000;
our $VERSION = '0.01';
-# Is Class::C3 installed locally?
-our $C3_INSTALLED;
-
BEGIN {
- # Don't do anything if 5.9.5+
+ # Alias our private functions over to
+ # the mro:: namespace and load
+ # Class::C3 if Perl < 5.9.5
if($] < 5.009_005) {
- # Find out if we have Class::C3 at all
- eval { require Class::C3 };
- $C3_INSTALLED = 1 if !$@;
-
- # Alias our private functions over to
- # the mro:: namespace
+ require Class::C3;
*mro::import = \&__import;
*mro::get_linear_isa = \&__get_linear_isa;
*mro::set_mro = \&__set_mro;
*mro::invalidate_all_method_caches
= \&__invalidate_all_method_caches;
}
+
+ # Provide no-op Class::C3::.*initialize() funcs for 5.9.5+
+ else {
+ no warnings 'redefine';
+ *Class::C3::initialize = sub { 1 };
+ *Class::C3::reinitialize = sub { 1 };
+ *Class::C3::uninitialize = sub { 1 };
+ }
}
=head1 NAME
in Perl 5.9.5 and higher.
This module provides a subset of those interfaces for
-earlier versions of Perl. It is a harmless no-op to use
-it on 5.9.5+. If you're writing a piece of software
-that would like to use the parts of 5.9.5+'s mro::
-interfaces that are supported here, and you want
-compatibility with older Perls, this is the module
-for you.
+earlier versions of Perl (back to 5.6.0 anyways).
+
+It is a harmless no-op to use it on 5.9.5+. If you're
+writing a piece of software that would like to use the
+parts of 5.9.5+'s mro:: interfaces that are supported
+here, and you want compatibility with older Perls, this
+is the module for you.
This module never exports any functions. All calls must
be fully qualified with the C<mro::> prefix.
on the given class, starting with itself. It does not include any
duplicate entries.
-On pre-5.9.5 Perls with MRO::Compat, explicitly asking for the C<c3>
-MRO of a class will die if L<Class::C3> is not installed. If
-L<Class::C3> is installed, it will detect C3 classes and return the
-correct C3 MRO unless explicitly asked to return the C<dfs> MRO.
-
Note that C<UNIVERSAL> (and any members of C<UNIVERSAL>'s MRO) are not
part of the MRO of a class, even though all classes implicitly inherit
methods from C<UNIVERSAL> and its parents.
=head2 mro::import
-Not supported, and hence 5.9.5's "use mro 'foo'" is also not supported.
-These will die if used on pre-5.9.5 Perls.
+This allows the C<use mro 'dfs'> and
+C<use mro 'c3'> syntaxes, providing you
+L<use MRO::Compat> first. Please see the
+L</USING C3> section for additional details.
=cut
sub __import {
- die q{The "use mro 'foo'" is only supported on Perl 5.9.5+};
+ if($_[1]) {
+ goto &Class::C3::import if $_[1] eq 'c3';
+ __set_mro(scalar(caller), $_[1]);
+ }
}
=head2 mro::set_mro($classname, $type)
-Not supported, will die if used on pre-5.9.5 Perls.
+Sets the mro of C<$classname> to one of the types
+C<dfs> or C<c3>. Please see the L</USING C3>
+section for additional details.
=cut
sub __set_mro {
- die q{mro::set_mro() is only supported on Perl 5.9.5+};
+ my ($classname, $type) = @_;
+ if(!$classname || !$type) {
+ die q{Usage: mro::set_mro($classname, $type)};
+ }
+ if($type eq 'c3') {
+ eval "package $classname; use Class::C3";
+ die $@ if $@;
+ }
+ if($type ne 'dfs') {
+ die q{Invalid mro type "$type"};
+ }
+
+ # In the dfs case, check whether we need to
+ # undo C3
+ if(defined $Class::C3::MRO{$classname}) {
+ Class::C3::_remove_method_dispatch_table($classname);
+ }
+ delete $Class::C3::MRO{$classname};
+
+ return;
}
=head2 mro::get_mro($classname)
Returns the MRO of the given class (either C<c3> or C<dfs>).
+It considers any Class::C3-using class to have C3 MRO
+even before L<Class::C3::initialize()> is called.
+
=cut
sub __get_mro {
my $classname = shift;
die "mro::get_mro requires a classname" if !$classname;
- if($C3_INSTALLED && exists $Class::C3::MRO{$classname}) {
- return 'c3';
- }
+ return 'c3' if exists $Class::C3::MRO{$classname};
return 'dfs';
}
=cut
+# In theory this could be made to work, but it would
+# be an insanely slow algorithm if any reasonably large
+# number of modules were loaded.
sub __get_isarev {
die "mro::get_isarev() is only supported on Perl 5.9.5+";
}
__invalidate_all_method_caches();
}
+=head1 USING C3
+
+While this module makes the 5.9.5+ syntaxes
+C<use mro 'c3'> and C<mro::set_mro("Foo", 'c3')> available
+on older Perls, it does so merely by passing off the work
+to L<Class::C3>.
+
+It does not remove the need for you to call
+L<Class::C3>'s C<initialize()>, C<reinitialize()>, and/or
+C<uninitialize()> at the appropriate times
+as documented in the L<Class::C3> docs.
+
+Because L<MRO::Compat> has L<Class::C3> as a pre-requisite,
+and requires it at C<use> time, you can blindly call
+those functions in code that uses L<MRO::Compat>.
+Under 5.9.5+ with L<MRO::Compat>, your calls to those
+functions will become a no-op and everything will work fine.
+
=head1 SEE ALSO
L<Class::C3>
projects / gitmo/MRO-Compat.git / commitdiff