如何在PHP类中停止进一步的方法？

Question

I am learning OOP with PHP. I am creating a class to extract XML data from a website. My question is how do I stop the given object from executing more methods if there is an error with the first method. For example, I want to send the URL:

class GEOCACHE {
   public $url;

   public function __construct($url)
   {
      $this->url=$url;
      if (empty($this->url))
      {
         echo "Missing URL";    
      }
   }
   public function secondJob() 
   { 
      whatever
   }
}

when I write like this:

    $map = new GEOCACHE ("");
    $map->secondJob("name");

How do I prevent the secondJob method from being executed in that given object without the script terminating?

Answer 1

Throw an Exception in the constructor, therefore the object will never be created

public function __construct($url)
{
   $this->url=$url;
   if (empty($this->url))
   {
      throw new Exception("URL is Empty");    
   }
}

You can then do something like this:

try
{
    $map = new GEOCACHE ("");
    $map->secondJob("name");
}
catch ( Exception $e)
{
    die($e->getMessage());
}