Using object property as default for method property

I'm trying to do this (which produces an unexpected T_VARIABLE error):

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

I don't want to put a magic number in there for weight, since the object I am using has a "defaultWeight" parameter that all new shipments get if you don't specify a weight. I can't put the defaultWeight in the shipment itself, because it changes from shipment group to shipment group. Is there a better way to do it than the following?

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

From stackoverflow cmcculloh

• This isn't much better:

  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();
  }
  

  From Kevin

• This will allow you to pass a weight of 0 and still work properly. Notice the === operator, this checks to see if weight matches "null" in both value and type (as opposed to ==, which is just value, so 0 == null == false).

  PHP:

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

  From pix0r

• @pix0r

  That is a good point, however, if you look at the original code if the weight is passed as 0 it uses the default weight.

  From Kevin

• try using a static class member.

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

  From paan

• Neat trick with boolean OR operator:

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

  From Michał Rudnicki