使用对象属性为默认方法财产

Question

我试图做到这一点（这会产生意想不到的T_VARIABLE错误）：

public function createShipment($startZip, $endZip, $weight = $this->getDefaultWeight()){} 

我不希望把一个神奇的数字在那里为重，因为我使用的对象具有"defaultWeight"参数，如果您未指定重量，则所有新货件都会得到。我不能将defaultWeight放入货件本身，因为它从发货组更改为货件组。有没有比以下更好的方法来做到这一点？

public function createShipment($startZip, $endZip, weight = 0){ 
    if($weight <= 0){ 
     $weight = $this->getDefaultWeight(); 
    } 
} 

Answer 1

这不是更好：

public function createShipment($startZip, $endZip, $weight=null){ 
    $weight = !$weight ? $this->getDefaultWeight() : $weight; 
} 

// or... 

public function createShipment($startZip, $endZip, $weight=null){ 
    if (!$weight) 
     $weight = $this->getDefaultWeight(); 
} 

Answer 2

这将允许你通过的0重量并仍能正常工作。注意===运算符，它检查是否在weight和type中匹配“null”（相对于==，它只是value，所以0 == null == false）。

PHP：

public function createShipment($startZip, $endZip, $weight=null){ 
    if ($weight === null) 
     $weight = $this->getDefaultWeight(); 
} 

Answer 3

您可以使用一个静态类部件保持默认：

class Shipment 
{ 
    public static $DefaultWeight = '0'; 
    public function createShipment($startZip,$endZip,$weight=Shipment::DefaultWeight) { 
     // your function 
    } 
} 

Answer 4

绝招用OR运算符：

public function createShipment($startZip, $endZip, $weight = 0){ 
    $weight or $weight = $this->getDefaultWeight(); 
    ... 
}