Question

I’ve got an Object Oriented library I wanted to add a method to, and while I’m fairly certain I could just go into the source of that library and add it, I imagine this is what’s generally known as A Bad Idea.

How would I go about adding my own method to a PHP object correctly?

UPDATE ** editing **

The library I’m trying to add a method to is simpleHTML, nothing fancy, just a method to improve readability. So I tried adding to my code:

class simpleHTMLDOM extends simple_html_dom {
  public function remove_node() {
    $this->outertext = "";
  }
}

which got me: Fatal error: Call to undefined method simple_html_dom_node::remove_node(). So obviously, when you grab an element in simpleHTML it returns an object of type simple_html_dom_node.

If I add the method to simple_html_dom_node my subclass isn’t what will be created by simplHTML … so stuck as to where to go next.

Answer 1

A solution would be to create a new class, that extends the one from your library — and, then, use your class, which have have all methods of the original one, plus yours.

Here’s a (very quick and simple) example :

class YourClass extends TheLibraryClass {
  public function yourNewMethod() {
    // do what you want here
  }
}

And, then, you use your class :

$obj = new YourClass();
$obj->yourNewMethod();

And you can call the methods of the TheLibraryClass class, as yours inherits the properties and methods of that one :

$obj->aMethodFromTheLibrary();

About that, you can take a look at the Object Inheritance section of the manual.

And, as you guessed, modifying a library is definitly a bad idea : you’ll have to re-do that modification each time you update the library !

(One day or another, you’ll forget — or one of your colleagues will forget ^^ )