Design Pattern: Decorator

Decorator is similar to Proxy.

Basically, decorator is an extension (or wrapper) of the original class (component) and adds features.

A decorator contains a pointer to the component class (initialized by the constructor), and the methods of the component overridden.

Example:

class ImgComponent {
private $src;
private $alt;
public function __construct($name, $src) { /* assign to properties*/ };
public function getHTML() {
  return "[ img src="{$this->src}\" alt=\"{$this->alt}\" /]";
}
}

Let's write a decorator:

class ImgWithCaption extends imgComponent
{
 private $caption;
 private $imgComponent;
 public function __construct(&$img, $caption) {
   $caption->imgComponent = $caption;
   $this->imgComponent = &$img;
 };

 public function getHTML() {
   return "<div><div>{parent::getHTML()}</div>
   <div> $caption</div></div>";
 }
}