Operator overload in Perl

gistfile1.pl

#!/usr/bin/env perl

use strict;
use warnings;

use File::Basename;
use lib dirname(__FILE__);

{
    package GS_URI;

    use strict;
    use warnings;

    use parent 'URI';
    use Scalar::Util qw(blessed);

    use overload
      '""'          => sub { $_[0]->canonical },
        'eq'          => sub {
            my($self, $other) = @_;

            print STDERR "overloaded eq\n";
            print STDERR "\$self: object - $self->{uri}\n";

            if( blessed $other && $other->isa(__PACKAGE__) ) {
                print STDERR "\$other: object - $other->{uri}\n";
            }
            else {
                print STDERR "\$other: string - $other\n";
                $other = __PACKAGE__->new($other) unless blessed $other;
            }

            return $self->canonical eq $other->canonical;
        },
          fallback => 1;

    sub new {
        my $class = shift;

        my $uri = URI->new(@_);

        return bless { uri => $uri }, $class;
    }

    sub canonical {
        return $_[0]->{uri}->canonical;
    }
}

my $uri1 = GS_URI->new("http://x.com/ blah /");
my $uri2 = "http://x.com/%20blah /";

# operator overloading works even if one side isn't an object
print "Yes\n" if $uri1 eq $uri2;

# order doesn't matter
print "Yes\n" if $uri2 eq $uri1;

# just to show it's actually working
print "No\n"  if $uri1 ne "http://blah.com";