使用對象屬性爲默認方法財產

Question

我試圖做到這一點（這會產生意想不到的T_VARIABLE錯誤）：

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

我不希望把一個神奇的數字在那裏爲重，因爲我使用的對象具有"defaultWeight"參數，如果您未指定重量，則所有新貨件都會得到。我不能將defaultWeight放入貨件本身，因爲它從發貨組更改爲貨件組。有沒有比以下更好的方法來做到這一點？

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

Answer 1

這不是更好：

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

這將允許你通過的0重量並仍能正常工作。注意===運算符，它檢查是否在weight和type中匹配「null」（相對於==，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

您可以使用一個靜態類部件保持默認：

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

Answer 4

絕招用OR運算符：

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