PHP7 Gains Scalar Type Hints(wiki.php.net)

    function validateOrderAmount($value) : int {
        $count = preg_match("/[^0-9]*/", $value);
        
        if ($count) {
            throw new InvalidOrderAmount("Order amount must contain only digits.");
        }

        $value = intval($value);

        if ($value < 1) {
            throw new InvalidOrderAmount("Order amount must be one or more.");
        }
        
        if ($value >= MAX_ORDER_AMOUNT) {
            throw new InvalidOrderAmount("You can only order ".MAX_ORDER_AMOUNT." at a time.");
        }
        
        return $value;
    }

    function processOrderRequest() {
        $orderAmount = validateOrderAmount($_REQUEST['orderAmount']);
    
        //Yay, our IDE/static code analyzer can tell that $amount is an int if the code reached here.
        placeOrder($orderAmount);
    }

    "use strict";