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package UNIVERSAL::ref;
BEGIN {
$UNIVERSAL::ref::VERSION = '0.14';
}
use strict;
use warnings;
use B::Utils;
our @hooked;
our @needs_truth = qw(overload);
sub import {
my $class = caller;
my %unique;
@hooked = grep { !$unique{$_}++ } ( @hooked, $class );
}
sub unimport {
my $class = caller;
@hooked = grep $_ ne $class, @hooked;
}
my $DOES;
BEGIN { $DOES = UNIVERSAL->can('DOES') ? 'DOES' : 'isa' }
sub _hook {
# Below, you'll see that there is special dispensation for never
# hooking the function named UNIVERSAL::ref::_hook. That's why this
# ref() is safe from predation by this module.
# Is this object asserting that it is an ancestor of any hooked class?
my $is_hooked;
my $obj_class = CORE::ref $_[0];
my $caller_class = caller;
# For any special classes needing truth, just return if we've got
# any of those.
for my $class (@needs_truth) {
if ( $caller_class->$DOES($class) ) {
# CORE::ref
return $obj_class;
}
}
#
for my $hooked_class (@hooked) {
# Find only hooked ancestries that pertain this object.
next unless $obj_class->$DOES($hooked_class);
# Check that the call wasn't made from within this object's
# ancestry. It has to be possible for an object to ask
# questions about itself without getting lies.
next if $obj_class->$DOES($caller_class);
return $_[0]->ref;
}
# CORE::ref
return $obj_class;
}
use XSLoader;
$| = 1;
XSLoader::load( 'UNIVERSAL::ref', $UNIVERSAL::ref::VERSION );
use B 'svref_2object';
use B::Utils 'all_roots';
my %roots = all_roots();
for my $nm ( sort keys %roots ) {
my $op = $roots{$nm};
next unless $$op;
next if $nm eq 'UNIVERSAL::ref::_hook';
if ( defined &$nm ) {
my $cv = svref_2object( \&$nm );
next unless ${ $cv->ROOT };
next unless ${ $cv->START };
}
_fixupop($op);
}
no warnings;
q[Let's Make Love and Listen to Death From Above];
__END__
=head1 NAME
UNIVERSAL::ref - Turns ref() into a multimethod
=head1 SYNOPSIS
# True! Wrapper pretends to be Thing.
ref( Wrapper->new( Thing->new ) )
eq ref( Thing->new );
package Thing;
sub new { bless [], shift }
package Wrapper;
sub new {
my ($class,$proxy) = @_;
bless \ $proxy, $class;
}
sub ref {
my $self = shift @_;
return $$self;
}
=head1 DESCRIPTION
This module changes the behavior of the builtin function ref(). If
ref() is called on an object that has requested an overloaded ref, the
object's C<< ->ref >> method will be called and its return value used
instead.
=head1 USING
To enable this feature for a class, C<use UNIVERSAL::ref> in your
class. Here is a sample proxy module.
package Pirate;
# Pirate pretends to be a Privateer
use UNIVERSAL::ref;
sub new { bless {}, shift }
sub ref { return 'Privateer' }
Anywhere you call C<ref($obj)> on a C<Pirate> object, it will allow
C<Pirate> to lie and pretend to be something else.
=head1 METHODS
=over
=item import
A pragma for ref()-enabling your class. This adds the calling class
name to a global list of ref()-enabled classes.
package YourClass;
use UNIVERSAL::ref;
sub ref { ... }
=item unimport
A pragma for ref()-disabling your class. This removes the calling
class name from a global list of ref()-enabled classes.
=back
=head1 TODO
Currently UNIVERSAL::ref must be installed before any ref() calls that
are to be affected.
I think ref() always occurs in an implicit scalar context. There is no
accomodation for list context.
UNIVERSAL::ref probably shouldn't allow a module to lie to itself. Or
should it?
=head1 ACKNOWLEDGEMENTS
ambrus for the excellent idea to overload defined() to allow Perl 5 to
have Perl 6's "interesting values of undef."
chromatic for pointing out how utterly broken ref() is. This fix
covers its biggest hole.
=head1 AUTHOR
Joshua ben Jore - jjore@cpan.org
=head1 LICENSE
The standard Artistic / GPL license most other perl code is typically
using.
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