use Scalar::Util qw(weaken);
use Devel::Peek;

sub Container::DESTROY {
    warn "Container $_[0] is destroyed!";
}

{
    my $container = bless {}, "Container";
    Dump $container;
    my $button = bless { container => $container }, "Button";
    push @{$container->{buttons}}, $button;
    Dump $container;
    weaken $button->{container};
    Dump $container;
}

__END__