Singletons
| From: | Christoph Boget | Date: | Mon, 20 Oct 2008 17:07:59 +0000 |
| Subject: | Singletons | ||
| Groups: | php.general | ||
| Request: | Send a blank email to php-general+get-282133@lists.php.net to get a copy of this message | ||
Ok, so why isn't this working as (I, at the very least) expected?
class singleTon
{
private static $thisObj = NULL;
private $thisProp = NULL;
public function __construct()
{
echo 'singleTon::__construct()<br>';
if( !is_null( singleTon::$thisObj ))
{
echo '$thisObj already set. returning it...<br>';
return singleTon::$thisObj;
}
singleTon::$thisObj = $this;
}
public static function singleton()
{
echo 'singleTon::singleton()<br>';
if( is_null( singleTon::$thisObj ))
{
$retval = new singleTon();
}
return singleTon::$thisObj;
}
public function setThisProp( $sVal )
{
$this->thisProp = $sVal;
}
public function getThisProp()
{
return $this->thisProp;
}
}
$one = singleTon::singleton();
$one->setThisProp( 'Joe' );
echo '$one->getThisProp();: [' . $one->getThisProp() . ']<br>';
echo '$one: [<pre>' . var_export( $one, TRUE ) .
'</pre>]<br>';
$two = new singleTon();
echo '$two->getThisProp();: [' . $two->getThisProp() . ']<br>';
$two->setThisProp( 'Bob' );
echo '$two: [<pre>' . var_export( $two, TRUE ) .
'</pre>]<br>';
echo '$one->getThisProp();: [' . $one->getThisProp() . ']<br>';
echo '$two->getThisProp();: [' . $two->getThisProp() . ']<br>';
echo '$one->getThisProp();: [' . $one->getThisProp() . ']<br>';
I would have thought that both $one and $two would be referencing the
same object but they aren't. Apart from making the constructor
private, is there any way I can ensure that there is ever only one
instance of an object?
thnx,
Christoph