Question

我正在尝试这样做（产生意外的T_VARIABLE错误）：

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

我不想在那里放一个幻数来表示重量，因为我使用的对象有"defaultWeight"参数，如果你没有指定重量，所有新货都会得到。我无法将defaultWeight放入货件本身，因为它会从货件组更改为货件组。有没有比以下更好的方法呢？

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

使用布尔OR运算符的巧妙技巧：

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

Answer 3

这将允许您传递0的权重并仍然正常工作。注意===运算符，它检查重量是否与值和类型中的“null”匹配（与==相反，这只是值，因此0 == null == false）。

PHP：

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

Answer 4

您可以使用静态类成员来保存默认值：

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

Answer 5

如果您使用的是PHP 7，则可以改善Kevin的回答：

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

使用object属性作为method属性的默认值

5 个答案: