CODEWITHSUNDEEP
phpdomdocument
konrados
konrados

Reputation: 1141

What is the reason behind DOMAttr extending DOMNode? Or, what's the purpose of having the DOMNode class in general

I'd like to know why the "DOMNode" class exists at all. It seems sensible only for the DOMElement to extend it. Therefor what's the purpose of it?

For example, why is the DOMAttr class ( http://php.net/manual/en/class.domattr.php ) based on DOMNode class? What is the relationship here? DOMAttr cannot have "childNodes" or... anything DOMNode provides.

It's just a key => value, isn't it?

To be precise, they do "share" something, when with new DOMAttr ('key','val') we get a DOMNode with nodeName == 'key' and nodeValue == 'val'; but... so what? Key/val pair still is not a DOM tree node, am I right?

Upvotes: 0

Views: 132

Answers (1)

apokryfos
apokryfos

Reputation: 40681

Short answer, this question is not really a PHP question because PHP is just implementing the W3C specification of the DOM document.

In the spec, a Node is any part of the tree, including attributes, elements and text. It's not a matter of why have the DOMNode because all these parts of the tree do share a lot of common properties which justifies them inheriting from a common parent.

Therefore it's fully justifiable why Element and Attribute would share a common ancestor in the interface design. I think the real question is why it was named a node when node is usually a vertex of a tree/graph.

Upvotes: 1

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