use strict;

END { print "END\n" };

{
    package SubRef;
    use Scalar::Util qw(weaken refaddr);

    sub DESTROY { my $self = shift; print "DESTROY ".ref($self) ."\n" }

    sub new {
        my $class = shift;
        my $copy;
        my $self = $copy = bless(sub { $copy->ok }, $class);
        weaken $copy;
        return $self;
    }

    sub ok { print "SubRef ok ".refaddr($_[0])."\n" }
}

{
    package ArrayRef;

    @ArrayRef::ISA = qw(SubRef);

    sub new {
        my $class = shift;
        return bless [], $class;
    }
}

{
    package CircularRef;

    @CircularRef::ISA = qw(SubRef);

    sub new {
        my $class = shift;
        my $s = {};
        $s->{self} = $s;
        return bless $s, $class;
    }
}


for (1..2) {
    my $sub  = SubRef->new;
    my $sub2 = SubRef->new;
    my $arr  = ArrayRef->new;
    my $cir  = CircularRef->new;
    $sub->();
    $sub2->();
}

print "After For\n";