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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.
745
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 ^^ )
104
You could do it with inheritance, but you could also use a decorator pattern if you do not need access to any protected members from SimpleHtml. This is a somewhat more flexible approach. See the linked page for details.
class MySimpleHtmlExtension
{
protected $_dom;
public function __construct(simple_html_dom $simpleHtml)
{
$this->_dom = $simpleHtml;
}
public function removeNode(simple_html_dom_node $node)
{
$node->outertext = '';
return $this;
}
public function __call($method, $args)
{
if(method_exists($this->_dom, $method)) {
return call_user_func_array(array($this->_dom , $method), $args));
}
throw new BadMethodCallException("$method does not exist");
}
}
You'd use the above like this
$ext = new MySimpleHtmlExtension( new simple_html_dom );
$ext->load('<html><body>Hello <span>World</span>!</body></html>');
$ext->removeNode( $ext->find('span', 0) );
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