use Scalar::Util qw( weaken );

sub new {
    my ( $class, $href ) = @_;
    my $self = { dbi => $$href{dbi} };

    {
        weaken( my $self = $self );
        $self->{helper} = Helper->new(
            helper_function => sub {
                $self->this_is_from_A(@_)
            },
        );
    }

    bless $self, $class;
}