Singleton in constructor

Question

why it's not work? I want create singleton for connect to db, autoloader, router.

static $singleton = null;

public function __construct(){
    if(empty(self::$singleton)){
        self::$singleton = new self;
        return self::$singleton;
    }
    return self::$singleton;
}

Answer 1

In php method __construct always return instance of class, you can't manipulate the returned value.

To do what you meant to do, you should use private __conctruct() and create next method for example public static getInstance() with your code:

static $singleton = null;

public function getInstance(){
    if(empty(self::$singleton)){
        $class = get_called_class();
        self::$singleton = new $class;
    }
    return self::$singleton;
}