Question

What I’d like ti achieve is that when I call $obj->CAT[15];
the $obj would check if the property CAT exists if not, get the value on the fly

public function __get($var){
if($var == "CAT") return $this->cats->get_cat($cat_id);
}

so my question is… how to get array’s value 15 from my example? to pass it to my get_cat method?

Answer 1

Have __get return an instance of ArrayAccess which will delegate to get_cat in its offsetGet method.

Something like this:

class CachedCategories implements ArrayAccess
{
  private $memcachedClient;

  public function __construct($memcachedClient)
  {
    $this->memcachedClient = $memcachedClient;
  }

  // Called when using `$cats[18] = "foo"`
  public function offsetSet($key, $value)
  {
    $this->memcachedClient->set($key, $value);
  }

  // Called when using `$cat = $cats[18]`
  public function offsetGet($key)
  {
    return $this->memcachedClient->get($key);
  }

  // Called when using `isset($cats[18])`
  public function offsetExists($key)
  {
    return $this->memcachedClient->get($key) !== false;
  }

  // Called when using `unset($cats)`
  public function offsetUnset($key)
  {
    $this->memcachedClient->delete($key);
  }
}

$cats = new CachedCategories($someMemcachedClient);
$cats[18];