Singleton syntax in PHP code

Question

I understand the singleton pattern, but I don't understand the following syntax:

 public static function get() { static $db = null; if ( $db == null ) $db = new DatabaseConnection(); return $db; } private function __construct() { $dsn = 'mysql://root:password@localhost/photos'; $this->_handle =& DB::Connect( $dsn, array() ); }

Why every time we call DatabaseConnection::get() we could ge the same singleton object? Because the code read from me will like:

 static $db = null; //set $db object to be null if($db==null) // $db is null at the moment every time because we just set it to be null // call the private constructor every time we call get() * $db = new DatabaseConnection(); return $db; // return the created

Then how the get() function could always return a same object?

I am new to Php, most of the syntax to me will read like java, please any one could explain this to me?

Also is there any instructions/tutorial that I could read for understanding more syntax sugar like:

 $array_object[] = $added_item

It seems to me that you are correct, and this wouldn't follow the Singleton pattern - quite confusing... I'd like to see if anyone disagrees. As for $array_object[] = $added_item, it just adds $added_item to the next available index of the $array_object array ;) Though if you're interested in where you can find out similar stuff, I usually just check php.net/manual/en — SharkofMirkwood
– SharkofMirkwood, Commented Jul 19, 2013 at 0:24
Also, if you put static $db = null; outside of the get() method, I think that would work just fine as it's only set to null the once. Maybe that's what you meant? — SharkofMirkwood
– SharkofMirkwood, Commented Jul 19, 2013 at 0:25

Jean Paul · Accepted Answer · 2013-07-19 01:34:05Z

1

Try this inside your class:

private static $db; public static function get(){ if(!self::$db){ self::$db = new DatabaseConnection(); } return self::$db; }

answered Jul 19, 2013 at 1:34

Jean Paul

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Tim Raynor Over a year ago

Yeah, I think this should work for singleton, just wonder the case that show on the example.

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