package MyBaseClass;

sub open_for_reading {
    my ($this, $params_ref) = @_;

    $params_ref ||= {};
    return $this->get_context('path' => $params_ref->{'path'} || $this->path);
}

package MyDerivedClass;

sub open_for_reading {
    my ($this, $params_ref) = @_;

    $params_ref ||= {};
    my $context = $this->SUPER::open_for_reading();
    if ($params_ref->{'join_longcalls'}){
        ... modify context
    }
    return $context;
}