PHP: Problems using Singleton pattern and understanding __clone method - php

Question

I am trying to implement the singleton pattern in php like described here in Example #2:
http://www.php.net/singleton
When I run the example code
$singleton = Example::singleton(); // prints "Creating new instance."
echo $singleton->increment(); // 0
echo $singleton->increment(); // 1
$singleton = Example::singleton(); // reuses existing instance now
echo $singleton->increment(); // 2
echo $singleton->increment(); // 3
it allways ends with Fatal Error 'Clone is not allowed.' directly after 'Creating new instance.'
I would expect that there is no reason for php to call the __clone-method.
In another real-life project of mine I want to have a singleton PlayerManager that holds Player-objects in an array (loaded only once in __construct) and has functions like GetPlayers() or GetPlayersByID($id).
In my script I write something like
$pm = PlayerManager::GetInstance();
$p1 = $pm->GetPlayerByID(0);
echo $p1->SomeNumber; //100
$p1->SomeNumber = 200;
$p2 = $pm->GetPlayerByID(0);
echo $p2->SomeNumber; //100 and not 200, as I would expect
Can someome give me some hints how to implement the PlayerManager using the Singleton pattern correct? I'm not sure if it is only a problem with the singleton or also a problem with returning object references...

Answer 1

I'm not quiet sure why you're getting that error (post your singleton class if you want help with that). Though I always preferred this version to the one you're using, it's a bit simpler: http://www.talkphp.com/advanced-php-programming/1304-how-use-singleton-design-pattern.html
So with the above, your code would look like:
class Counter
{
$CurrentValue = 0;
// Store the single instance of Database
private static $m_pInstance;
private function __construct() { }
public static function getInstance()
{
if (!self::$m_pInstance)
{
self::$m_pInstance = new Counter();
}
return self::$m_pInstance;
}
public function increment ($by)
{
$this->CurrentValue += $by;
return $this->CurrentValue;
}
public function getValue ()
{
return $this->CurrentValue;
}
}
And to use:
$counter = Counter::getInstance();
echo $counter->increment(); // 0
echo $counter->increment(); // 1
$counter = null;
$counter = Counter::getInstance(); // reuses existing instance now
echo $counter->increment(); // 2
echo $counter->increment(); // 3
Tell me how that works out for you.