$actions = $CGI->param ('action');
$to_do = new INVOICES();
if ($actions eq 'delayedinv') { $to_do->delayedinv() }
elsif ($actions eq 'del_inv') { $to_do->del_inv() }
elsif ($actions eq 'payed' ) { $to_do->payed () }
elsif ($actions eq 'stats' ) { $to_do->stats () }
... skip ...
else { $to_do->defscreen()}