PHP5 OOP: Extending DOMDocument

[448191]

I've run into an issue I can't get my head around...

I've got two home-brew classes; DomXml and DomXhtml.

I want DomXhtml to extend DomXml and DomXml to extend php5's build-in DomDocument class.

No problem. Yet.

I also want to use the build-in class DomImplementation wich I need to create a DOCTYPE section.

Problem.

Why?
DomDocument doesn't extend DomImplementation, like you might expect (I did). Instead, DomImplementation uses a method called createDocument to create an instance of DomDocument.

Example:

<?php
//Create an instance of the DOMImplementation class
$domImpl = new DOMImplementation;
//Create a DOMDocumentType section
$docType = $domImpl->createDocumentType($rootName,$publicId,$systemId);
//Creates a DOMDocument instance
$domDoc = $domImpl->createDocument('', $rootName, $docType);
?>

You're starting to see the problem here?

Got a fix, anyone?

[448191]

I'd like to have DomDocuments meths and props available to DomXml and DomXhtml in the same instance, but I can't extend DomDomcument because I need DomIplementation to create the DomDocument intance. If I don't use DomImplementation I can't get my docs to validate, wich also disables the use of getElementById.

I thought about creating a local instance of both DomDocument and DomImplementation made avialable to DomXhtml by way of a public prop, but that's very inconvenient.

Accessing of DomDocument methods by way of a DomXml or DomXhtml instance would look very patchy, unless I define a custom method within DomXml for each one I plan on using. The latter seems very inefficient.

Example:

<?php
class DomXml {
	public $domDoc;	
	function __construct($rootName,$publicId,$systemId)	{	
		$domImpl = new DOMImplementation;
		$docType = $domImpl->createDocumentType($rootName,$publicId,$systemId);
		$this->domDoc = $domImpl->createDocument('', $rootName, $docType);	
	}
	public function getElementById($id) {
		return $this->domDoc->getElementById($id);
	}
}
//Usage
$doc = new DomXml('test','Test XML File','DTD/test.dtd');
//Option 1:
$nodes = $doc->domDoc->getElementsByTagname('testtag');
//Option 2:
$node = $doc->getElementById('testnode');
?>

I can't say I like either of these options. :queasy:

If you can think of something better, please let me know.