Extend Class with Final Constructor on PHP

Question

I want extend class which have final constructor (in my case it's SimpleXMLElement), but i have problems because when i use:

    class myclass extends SimpleXMLElement {
        function __construct($xmlVersion='1.0', $xmlEncoding='ISO-8859-1', $rootName='root'){
            parent::__construct("<?xml version='$xmlVersion' encoding='$xmlEncoding'?><$rootName />");
        }

I get error:

Fatal error: Cannot override final method SimpleXMLElement::__construct()

When i delete constructor i get this error:

Fatal error: Uncaught exception 'Exception' with message 'SimpleXMLElement::__construct() expects at least 1 parameter, 0 given'

I miss something or doesn't understand how properly call parent constructor which is final. I don't want override methods just expand class, but i can't expand because it required __construct(). So i missed something and back where started.

Can somebody explain where i was wrong?

Answer 1

I just went through this exact thing. You don't need to extend it. Make a class that holds SimpleXMLElement objects. I believe this is what Nikola meant.

class XmlResultSet
{
    public $xmlObjs = array();

    public function __construct(array $xmlFiles)
    {
      foreach ($xmlFiles as $file) {
          $this->xmlObjs[] = new XmlResult($file);
      }
    }
}

class XmlResult
{
    private $xmlObj;

    public function __construct($file)
    {
        try {
            $this->xmlObj = new SimpleXMLElement($file, 0, true);
        }
        catch (Exception $e) {
            throw new MyException("Invalid argument ($this)($file)(" . $e .
            ")", PHP_ERRORS);
        }
    }

    public function otherFunctions()
    {
        return $this->xmlObj->movie['name']; // whatever
    }
}