Question

The following code gives me an error

class One{    
    public $var = 10;
}

class Two extends One{
    public $var = 20;
    function __construct(){
        $this->var = parent::$var;
    }
}

$two = new Two();
echo $two->var;

Answer 1

If you want to get like this parent::$var (so static), define var as static both in One and Two.

This will work;

class One {    
    public static $var = 10;
}

class Two extends One {
    public static $var = 20;

    public function __construct() {
        // this line creates a new property for Two, not dealing with static $var
        $this->var = parent::$var;
        // this line makes real change
        // self::$var = parent::$var;
    }
}

$two = new Two();
echo $two->var; // 10
echo $two::$var; // 20, no changes
echo Two::$var;  // 20, no changes

// But I don't recommend this usage
// This is proper for me; self::$var = parent::$var; instead of $this->var = parent::$var;